Immune dysfunction in inflammatory bowel disease

REVIEW ARTICLE Immune dysfunction in inflammatory bowel disease MANUELA G. NEUMAN TORONTO, ONTARIO, CANADA

Ulcerative colitis (UC) and Crohn’s disease (CD) are idiopathic inflammatory bowel diseases (IBDs) that are characterized by chronic periods of exacerbation and remission. Research into the immunopathogenesis of IBD adds support to the theory that the disease results from a dysfunctional regulation of the immune system that leads to the polarization of intestinal immune cells toward a Th1 (T helper) response. The immunologic factors that mediate alterations in intestinal homeostasis and the development of intestinal mucosal inflammation have been at the forefront of IBD research. Cytokines, which are important regulators of leukocyte trafficking and apoptotic cell death, have emerged as essential immune molecules in the pathogenesis of IBD. In this study, recent advances in the understanding of the dynamism of cytokines and the consequences for mucosal immunity and inflammation in IBD are discussed. Furthermore, this study highlights the potential use of cytokines, anti-cytokine antibodies, and cytokine-related biologic therapies as novel targets for the treatment of IBD. (Translational Research 2007;149:173–186) Abbreviations: AICD ⫽ activation-induced cell death; CD ⫽ Crohn’s disease; E ⫽ endothelial; EC ⫽ endothelial cell; ECM ⫽ extracellular matrix; IBD ⫽ inflammatory bowel disease; ICAM ⫽ intercellular adhesion molecule; ICE ⫽ interleukin-1 converting enzyme; IEL ⫽ intraepithelial lymphocyte; IFN-␥ ⫽ interferon-␥; IL ⫽ interleukin; IL-1Ra ⫽ interleukin-1 receptor agonist; Fas-l ⫽ Fas-Fas ligand; L ⫽ leukocyte; LPMC ⫽ lamma propria mononuclear cell; MAdCAM-1 ⫽ mucosal address in cell adhesion molecule-1; NF-␬B ⫽ nuclear factor-␬B; P ⫽ platelet; sIL-6R ⫽ soluble IL-6 receptor; sTNF␣R ⫽ soluble TNF-␣ receptor; TGF-␤ ⫽ transforming growth factorbeta; Th ⫽ T helper; TNF-␣ ⫽ tumor necrosis factor-alpha; UC ⫽ ulcerative colitis; VCAM-1 ⫽ vascular cell adhesion molecule-1; VEGF ⫽ vascular endothelial growth factor

I

nflammatory bowel disease (IBD) is a chronic disorder of the gastrointestinal tract that may manifest as either Crohn’s disease (CD) or ulcerative colitis (UC). The disease is characterized by unpredictable

From the Department of Pharmacology and Institute of Drug Research, University of Toronto, Toronto, Ontario, Canada. Submitted for publication September 3, 2006; revision submitted November 19, 2006; accepted for publication November 21, 2006. Reprint requests: Manuela Neuman, PhD, Director of in Vitro Drug Safety and Biotechnology, MaRS Discovery Centre, 101 College Street, Suite 200, Lab 351, Toronto, Ontario, Canada, M5G 1L7. e-mail: [email protected]. 1931-5244/$ – see front matter © 2007 Mosby, Inc. All rights reserved. doi:10.1016/j.trsl.2006.11.009

attacks of inflammation of the intestine, and it is estimated to affect as many as 1.4 million persons in the United States and 2.2 million persons in Europe.1 Clinical symptoms include weight loss, diarrhea accompanied by blood, and abdominal pain.2 Disease progression is often accompanied by an increase in granulomas and activated monocytes, which produce significant amounts of eicosanoids and cytokines.3 Affected areas typically reveal transmural inflammation characterized by lymphoid hyperplasia, submucosal edema, ulcerative lesions, and fibrosis.4 UC may be distinguished histologically from CD by the presence of localized inflammation in the superficial layer of the colon mucosa.5 The dysregulation of sodium absorption in the distal colon involving the epithelial sodium channel is 173

174

Neuman

considered a distinguishing characteristic that may be responsible for the observed diarrhea in UC.6 Symptoms of IBD often seem to be a direct result of the inflammatory process itself, and they frequently vary, depending on the location of the inflammation. As inflammation is a continuous process, direct assessment of the level of endoscopic grading may provide a quantitative presymptomatic measure of impending disease relapse or the transformation of the inflammatory process to malignancy.7 Knowledge of objective evidence of inflammatory activity is important. It may allow targeted treatment at an earlier stage (with fewer side effects) to avoid a relapse and may allow the assessment of new therapeutic strategies for maintenance of symptomatic remission.8 CD and UC are related conditions characterized by periods of remission marked by episodes of clinical relapse. Clinical relapse is usually caused by acute intestinal inflammation. Treatment is primarily aimed at reducing inflammation during relapse and secondarily at prolonging the time spent in remission of clinical symptoms. The etiology of IBD is unknown, but the condition seems to be the result of a combination of environmental, genetic, and immunologic factors in which an uncontrolled immune response within the intestinal lumen leads to inflammation in genetically predisposed individuals.9 Dysfunctions of the intestinal immune system and cross-reactivity against host epithelial cells have been implicated as major mechanisms by which inflammation occurs.10 During acute inflammatory episodes, the mucosal lining of the intestine displays a characteristic inflammatory infiltrate of mast cells, lymphocytes, macrophages, and activated neutrophils.11 Damage to the epithelial gut mucosa in IBD has been linked to elevated levels of effector immune cells such as activated CD4⫹ and CD8⫹ cytotoxic T cells, cytolytic intraepithelial lymphocytes (IELs), and perforin- and granzyme-containing T cells.12,13 In view of the increasing use of anti-cytokine-based therapies to treat autoimmune diseases, the role of specific cytokines in the pathogenesis of IBD has become a highly relevant area of investigation. This study seeks to clarify and establish the role of cytokines as key immune mediators in the pathogenesis of IBD while highlighting the areas of cytokine research that are currently contributing to new therapeutic treatments. DYSREGULATION OF IMMUNE FUNCTION Tolerance to self-antigens. The gastrointestinal tract acts as a barrier against a vast array of foreign antigens from food and intestinal bacteria that are contained within its lumen; it has therefore been suggested that an alteration of the mucosal immune system toward luminal antigens may play a crucial role in the pathogenesis

Translational Research April 2007

of IBD.14 The origin of the antigens responsible for IBD has not yet been elucidated, but a likely mechanism involves an antigen-presenting cell forming a complex with an endotoxin-derived antigen.15 T helper (Th) lymphocytes recognize this complex, are activated, and start to produce cytokines.16 In the normal gut, the mucosal immune system can mount an immune response to pathogenic material while maintaining tolerance to antigens derived from food and other bacteria. IBD is thought to be caused by a loss of tolerance against the autologous bacterial flora of the intestine.17 Tolerance to self-antigens is achieved either by clonal ignorance (when self-antigens are ignored by the immune system) or through the death of developing lymphocytes when they encounter a high concentration of self-antigens in the lymphoid organs, bone marrow, or peripheral tissues.18 No specific dietary component has been identified, although several infectious agents have been proposed, including species of Myobacterium, Listeria, Yersinia, and Escherichia coli.19 Immune responses are initiated when either cytotoxic T lymphocyte CD8⫹ cells or CD4⫹ Th cells in the intestinal lumen recognize a bacterial antigen. Intestinal epithelial cells lacking conventional co-stimulatory molecules CD80 and CD86 may function as antigen-presenting cells for CD4⫹ and CD8⫹ T cells via the novel co-stimulatory molecules B7H and B7-H1.20 These T lymphocytes bind to small molecules and specific peptides in the groove of the surface human leukocyte antigen, thus initiating the immunological cascade responsible for eradicating the antigenic material. Controlled versus harmful inflammatory responses. The presence of abundant leukocytes in the intraepithelial and subepithelial intestinal tissue causes a state of “controlled inflammation” that is necessary for the maintenance of mucosal homeostasis.21 Once the harmful foreign antigen has been eradicated, T lymphocytes of the intestinal mucosa require a method to attenuate the local immune response. Immune suppression in the gut may be achieved by means of CD4⫹CD25⫹ cells, which are produced in the thymus and peripheral blood of humans.22 Leptin, a cytokine-like protein produced by adipocytes, may also play a key role in controlling the inflammatory response by increasing the production of pro-inflammatory cytokines.23 Most importantly, immune cell death, or apoptosis, provides a built-in physiological mechanism for reducing the life span of aggressively overproliferative T cells.24 Apoptosis may be triggered in physiological or pathological conditions by a variety of intracellular and extracellular signals and reduced or enhanced by several inhibitory and regulatory factors.25 Inhibition of T-cell apoptosis has been implicated in the development of several autoimmune conditions such as diabetes, asthma, rheumatoid

Translational Research Volume 149, Number 4

arthritis, congenital lymphoproliferative syndrome, and IBD.26 –28 Failure to regulate T-cell responses in the intestinal or colonic mucosa leads to an inappropriate, sustained, and injurious immunologic reaction involving the activation of immune cells such as neutrophils, macrophages, and cytotoxic T cells.29 The release by T cells of reactive oxygen and nitrogen metabolites, cytotoxic proteins, lytic enzymes, and cytokines leads to exaggerated death of enterocytes and pathological inflammation of the host tissue. Acquired immunity and the Th1 response. The acquired immune response to foreign antigens involves the production of cytokines and the induction of responsiveness to cytokines by the expression of specific cell-surface cytokine receptors on the responding target cells. Exogenous antigens enhance the production of various cytokines from the intestinal epithelium such as interleukin (IL)-1, IL-6, IL-8, IL-15, and tumor necrosis factor-alpha (TNF-␣).30 –32 These cytokines may disturb the balance of immune cells and other mediators in the intestinal tissue. Upon activation by specific antigens, or through stimulation by phagocytes or other immune mediators, CD4 and CD8 cells may differentiate into Th1 or Th2 subsets, populations of T cells that may be classified according to their ability to secrete specific cytokines.33 Triggering the CD8⫹ activation pathway of Th1 cells produces a dramatic increase in pro-inflammatory cytokines, which then initiates a cascade of biochemical and morphological changes in T cells leading to the proliferation of antigen-specific T-cell clones and development of effector functions. Th1 responses are characterized by secretion of IL-1, IL-2, IL-6, IL-12, IL-18, TNF-␣, and interferon-␥ (IFN-␥), and they help direct the immune response toward cell-mediated effector functions and delayedtype hypersensitivity reactions. Studies showing increased levels of TNF-␣, IFN-␥, IL-1, and IL-6 in the intestinal tissue and peripheral blood of CD and UC patients polarize immune activity in IBD toward a Th1 response.34,35 UC seems to exhibit the additional involvement of a defective Th2 response that is characterized by secretion of IL-4, IL-5, and IL-10.36,37 SYNTHESIS AND FUNCTION OF CYTOKINES Cytokines as immune mediators. Cytokines are small peptide proteins produced by immune cells that facilitate communication between cells, stimulate the proliferation of antigen-specific effector cells, and mediate the local and systemic manifestation of inflammation in autocrine, paracrine, and endocrine tissues.38 Cytokines may be divided into 3 classes based on their functions in mediating immune responses and inflammation. Pro-inflammatory cytokines such as IL-1, IL-6, and TNF-␣ induce inflammatory processes by binding selectively to receptors that

Neuman

175

are expressed on different types of immune cell membranes.39 Binding of pro-inflammatory cytokines amplifies the immune response by enhancing the proliferation of T cells, promoting leukocyte infiltration, and facilitating cell– cell signaling. Interleukin-1 receptor agonist (IL-1Ra), soluble TNF-␣ receptor (sTNF-␣R), IL-4, IL-5, IL-10, and transforming growth factor-beta (TGF-␤) are considered to be anti-inflammatory or immunosuppressive cytokines because they play a role in limiting the expansion of specific lymphocytes and returning activated macrophages and other inflammatory cells to their normal resting state.40 In addition, IFN-␥, IL-12, and IL-18 have a critical role in immunomodulation in that their primary physiological role involves modulating the actions of various pro-inflammatory effector molecules. Cytokines play a key role in determining the nature of the immune response in IBD by rapidly synthesizing and secreting inflammatory mediators such as reactive oxygen metabolites, nitric oxide, leukotrienes, platelet-activating factor, and prostaglandins.41– 43 Activation of the transcription factor NF␬B induces macrophages, lymphocytes, and polymorphonuclear neutrophils to synthesize and secrete the pro-inflammatory cytokines IL-1, IL-6, and TNF-␣.44 Pro-inflammatory cytokines TNF-␣, IL-1, and IL-6. Th1 lymphocytes orchestrate much of the inflammation in IBD mainly via production of TNF-␣, a 17-kD pleiotropic cytokine produced by macrophages, monocytes, and T cells. TNF-␣ exerts its pro-inflammatory effects through increased production of IL-1␤ and IL-6, expression of adhesion molecules, proliferation of fibroblasts and procoagulant factors, as well as initiation of cytotoxic, apoptotic, and acute-phase responses.45,46 TNF-␣ is one of the best-characterized agonists of the p38 and c-Jun Nterminal kinase, and it cascades 2 important mitogenactivated protein kinase pathways in the orchestration of inflammatory responses.47 TNF-␣ seems to exert a stimulatory effect on cells, which produce IFN-␥ in synergy with factors from non-lymphocyte lamma propria mononuclear cell (LPMC) and can act with prostaglandin-E2 to stimulate IL-12-mediated T-cell production of IFN-␥.48 Binding of IFN-␥ to specific cell-surface receptors results in the activation of multiple intracellular signaling cascades, leading to the synthesis of proteins that mediate antiviral, growth inhibitory, and immunomodulatory responses.49 The TNF-like factor TL1A seems to stimulate IFN-␥ secretion by binding to the death domain receptor DR3. A higher percentage of cells express the TL1A receptor DR3 in mucosal biopsies taken in CD and UC,50 and increased synthesis of IFN-␥ has been observed to correlate with severity of disease in IBD patients.51 The interrelation between TNF-␣ and IFN-␥ is supported by the finding of sharp reductions in the number of IFN-␥-

176

Neuman

producing LPMC in colonic biopsies from anti-TNF-␣treated patients.52 Studies correlating increased production of TNF-␣ with clinical disease activity have implicated TNF-␣ as a key inflammatory mediator in the pathogenesis of IBD. Clinical studies have reported a dramatic improvement in CD patients treated with a human–mouse chimeric TNF-␣neutralizing antibody (infliximab).53,54 Animal studies have demonstrated abrogation of colitis induction in a mouse TNF-␣ knockout model55 and the lethal exacerbation of colitis in mouse models harboring a TNF-␣ transgene.56 Increased TNF-␣-secreting cells and the spontaneous production of TNF-␣ have been reported in studies of isolated LPMC in inflamed and uninvolved IBD mucosa.57,58 Several studies have reported that elevated serum levels of TNF-␣ correlate with clinical and laboratory indices of intestinal disease activity, with the highest correlation found in colonic CD.59,60 The finding that increased production of TNF-␣ is present in noninflamed or nonactive IBD is supported by a study that found serum TNF-␣ concentrations to be only moderately increased in CD patients,61 suggesting that subclinical immune alterations may be present in some patients. In addition to the pro-inflammatory effects of TNF-␣, IL-1 seems to be important in the pathogenesis of IBD because of its immunological upregulatory and pro-inflammatory activities. The IL-1 system consists of IL-1␣ and IL-1 ␤, both of which are produced by various cell types through the initiation of cyclooxygenase type 2, type 2 phospholipase A, and inducible nitric oxide synthetase.63 The IL-1 receptor antagonist IL-1Ra is produced by intestinal epithelial cells and can inhibit the pro-inflammatory actions of IL-1 by binding to IL-1 receptors on target cells and competitively counteracting the effects of IL-1.64 The findings of high plasma and tissue levels of IL-1Ra in patients with IBD indicate that IL-1Ra may be part of the host mechanism for downregulating inflammation.65– 67 The IL-1Ra/IL-1 ratio decreases with increasing IBD activity, while remaining constant in uninvolved CD and inflammatory control specimens.68 The mucosal imbalance of intestinal IL-1 and IL-1Ra observed in IBD patients suggests that insufficient production of endogenous IL-1ra may contribute to the pathogenesis of chronic gut inflammation.69 Increased levels of IL-1 in IBD may also be the result of stimulation of colonic macrophages that can activate interleukin-1 converting enzyme (ICE) and hence release mature IL-1␤ into the colonic mucosa.70 One mechanism of loss of resident macrophages from normal mucosa and of recruited macrophages from IBD mucosa is by apoptosis. As a result, it has been proposed that inhibition of the enzymatic activity of ICE could inactivate IL-1, leading to the inhibition of apoptotic mechanisms.71 Inhibitors of caspase-8 and caspase-10 significantly reduced TNF-␣/butyrate-induced

Translational Research April 2007

apoptosis in colonic epithelial cells in vitro, suggesting that caspase inhibition could be a useful therapeutic technique in the treatment of IBD.72 In contrast to IL-1, IL-6 is a pleiotropic cytokine that exerts its pro-inflammatory effects largely by means of its soluble IL-6 receptor (sIL-6R), which acts as an agonist of IL-6-mediated cell responses.73 IL-6 and sIL-6R play a central role in a multitude of immunologic reactions and have been implicated in the immune regulation and inflammation of IBD. Elevated circulating levels of sIL-6R have been detected in active disease stages of CD and UC, as opposed to inactive disease or other forms of colitis, suggesting that natural sIL-6R may augment the role of IL-6-dependent immune processes.74 IL-6 is involved in trans-signaling and can transduce signals into cells lacking the IL-6R when it forms a complex with sIL-6R. Genetically engineered sIL-6R enhances IL-6 induction of acutephase proteins in vitro when bound in an IL-6R–IL-6 complex.75 Blockade of IL-6 trans-signaling causes T-cell apoptosis, indicating that the IL-6 –sIL-6R system mediates the resistance of T cells to apoptosis in CD.76 Yamamoto et al77 introduced the anti-IL-6 receptor monoclonal antibody to a murine colitis model and found that the treatment reduced IFN-␥, TNF-␣, and IL-1 ␤ mRNA, as well as suppressed expression of several intracellular adhesion molecules in the colonic vascular endothelium. The anti-IL-6 receptor monoclonal antibody also abrogates murine colitis by effectively blocking the recruitment of leukocytes and increasing T-cell apoptosis.78 Elevation in IL-6 serum levels during remission in CD patients was found to be a clinically relevant parameter for predicting inflammatory activity79 as well as for corresponding with a high frequency of disease relapse.80 Most recently, several investigations into IL-18 have occurred, a newly described pro-inflammatory cytokine produced by intestinal epithelial cells that has been implicated in the induction of pro-inflammatory cytokines and Th1 polarization observed in CD lesions. IL-18, originally identified as an IFN-␥ inducing factor, shares similarities with the IL-1 family in terms of its structure, processing, receptor, signal transduction pathway, and pro-inflammatory properties.81 A local increase of IL-18 expression has been demonstrated in chronic lesions of CD compared with uninvolved areas or normal controls,82 and an increase in IL-18 was also shown to be accompanied by marked increases in IL-18 receptor-positive immune cells as well as intense transcription of IL-18-induced cytokines such as IFN-␥, IL-1 ␤, and TNF-␣.83 Furthermore, in the presence of IL-18, T cells from the inflamed tissue of CD patients have been shown to produce less IL-10 than control tissue.84 Although recombinant IL-18 alone induces significant proliferative responses in freshly isolated mucosal lymphocytes from CD patients,85,86 synergy be-

Translational Research Volume 149, Number 4

tween IL-12 and IL-18 in activated macrophages may be a potent regulatory mechanism driving lamina propria lymphocytes toward a Th1 response in IBD.87 Analysis of IL-18-deficient mice has revealed an important role of IL-18 in the activation of macrophages and natural killer cells in the context of infection with intracellular bacteria or parasites.88,89 It has been reported that the pro-inflammatory cytokine IL-12 may act in synergy with IL-18 to promote induction of IFN-␥, leading to severe gut inflammation in mice.90 The development of Th1 CD4⫹ T cells in the intestinal mucosa is driven by IL-12 produced from activated macrophages and IL-18 produced from activated macrophages and epithelial cells. The synergistic effect is mainly caused by mechanisms involving the upregulation of the IL-18 receptor by IL-12.91 IL-12 is a known pro-inflammatory cytokine with a well-characterized role in the Th1 response that involves driving the synthesis IFN-␥ by naïve T cells.92,93 Furthermore, several studies have confirmed that IL-12 alone is upregulated in the intestinal mucosa of CD and UC patients.94,95 Anti-inflammatory cytokines IL-10, IL-4, and TGF-␤. Evidence for the counterbalancing of immune activity in IBD toward a Th2 response involves animal studies of the Th2 cytokine IL-10. IL-10 is an anti-inflammatory cytokine that inhibits both antigen presentation and subsequent release of pro-inflammatory cytokines, thereby attenuating mucosal inflammation. IL-10 can inhibit the effector functions of activated macrophages and monocytes in vitro and downregulate the production of inflammatory cytokines such as IFN-␥ and IL-2 by Th1 lymphocytes.96 The pivotal role played by IL-10 within the mucosal immune system is demonstrated both by the chronic ileocolitis that develops in gene-targeted IL-10 knockout mice and by its therapeutic efficacy in several animal models of colitis. Animal models of both Th1- and Th2-mediated colitis generated by functional deletion of critical cytokines have shown that an inactivation of IL-10 in mice results in an increased production of IL-12 and IFN-␥.97,98 In the presence of an unspecified antigen within the gut lumen, these mice develop an inflammatory bowel disease-like syndrome that is ultimately fatal. In murine experimental colitis, inhibition of mucosal addressin, a cell adhesion molecule, allows an amelioration of intestinal inflammation.99 Kakazu et al3 reported that actively inflamed tissues and granulomas of CD show increased expression of IFN-␥ and IL-12, whereas expression of IL-2, IL-4, and IL-10 is not increased in these areas. Schreiber et al documented a dramatic decrease in the secretion of pro-inflammatory cytokines from IBD phagocytes and LPMC in vitro.100 Most recently, Melgar et al101 reported a highly significant increase in IL-10 mRNA

Neuman

177

levels in T lymphocytes and in IL-10-positive cells in the colons of UC patients. Overall, 2 anti-inflammatory cytokines whose roles are less well characterized in IBD include IL-4 and TGF-␤. IL-4 is a stimulatory molecule for both B and T cells, which has known immunosuppressive effects in the intestine.102 T-cell receptor alpha chain-deficient mice treated with anti-IL-4 mAb showed a decrease in Th2-type mRNA cytokine production and an increase in expression of IFN-␥, suggesting that IL-4 plays a major role in inducing Th2-type CD4(⫹) cells in the gut to shift to a Th1 response.103 IL-4 inhibits the release of TNF-␣ and IL-1,104 suppresses human macrophage colony formation,105 and reduces the synthesis of monocyte-derived H2O2.106 One study has reported that administration of IL-4 led to a significant reduction of the vascular endothelial growth factor (VEGF) production by peripheral blood mononuclear cells of both active CD and UC patients.107 Similarly, TGF-␤ is an inhibitory cytokine recognized as a key regulator of immunological homeostasis and inflammatory responses. Reduced TGF-␤ activity is considered to be responsible for the development of autoimmune disorders in several pathologic conditions including IBD.108 UC patients have exhibited increased production of TGF-␤1 by LPMC as compared with both CD patients and controls,109 highlighting that although TGF-␤ acts on the systemic immune system to promote a potent immunosuppressive effect, locally TGF-␤ may demonstrate pro-inflammatory properties. Evidence suggests that TGF-␤ can act in concert with epidermal growth factors, insulin-like growth factors, fibroblast growth factors, and VEGF to protect host tissue from luminal challenges and facilitate repair of mucosal injury in IBD.110 –112 IMMUNE MECHANISMS OF PATHOGENICITY Dysregulation of T-cell apoptosis. Defective mucosal T-cell apoptosis is likely to play a pivotal role in the pathogenesis of IBD. Support for this hypothesis comes from studies that have investigated (1) the Bcl-2/Bax protein family, (2) the survival factor nuclear factor-␬B (NF-␬B), and (3) the Fas ligand system. The family of Bcl-2-related proteins is the most significant class of gene products that regulate apoptosis.113 This family consists of several proteins with opposing activity, such as Bcl-2, which protects from apoptosis, and Bax, which promotes apoptosis. The relative balance between the agonist and the antagonist proteins affects how well a cell responds to apoptotic signals, thereby determining the degree of cell survival of T cells. The Bcl-2/Bax ratio is elevated in CD, a finding that suggests increased resistance of T cells in the mucosa of patients with CD and is consistent with observations of apoptotic resistance of immune cells in rheumatoid

178

Neuman

arthritis, aging, neoplasia, and autoimmune disease.114,115 Levels of expression of Bax protein are markedly reduced in inflamed UC colonic epithelium, demonstrating the downregulation of Bax in inflamed colonic epithelium.116 Mice positive for Bax gene expression have demonstrated a death receptor-mediated apoptotic pathway that was absent in mice lacking Bax expression.117 Studies of Bcl-2 homologs in the normal human intestinal epithelial cells in vitro demonstrate that regulation of cell survival may involve more complicated interactions than Bcl-2/Bax, as individual homologs such as Bcl-XL, Mcl-1, Bax, Bak, and Bad may be modulated individually by mitogen-activated protein kinases, focal adhesion molecules, and p38 isoforms.118 Cytokines and local oxygen concentrations can regulate cellular levels of Mcl-1 via transcription and posttranscriptional modification, thus influencing the inflammatory response by controlling the survival time of neutrophils in mucosal tissue.119 The alteration in the ratio of Bax/Bcl-2 in CD suggests that an imbalance in these proteins may favor resistance of mucosal T cells to apoptotic signals. In addition to Bax/Bcl-2 in maintaining colonic homeostasis, much investigation has surrounded the FasL system, a major pathway responsible for inducing apoptosis of T cells and enterocytes in the colonic mucosa.120 Fas is a type I transmembrane protein and a member of the TNF receptor superfamily that may be expressed constitutively by gut lamina propria T cells.121 FasL is a type II transmembrane protein that is expressed on cytotoxic T cells and that induces apoptosis of cells expressing Fas.122 Pro-inflammatory cytokines seem to play a central role in activating the Fas–FasL system. IFN-␥123,124 and IL-2125 have been shown to induce expression of Fas on both naïve and mature T cells in vitro. In an epithelial in vivo cell model, treatment with the anti-inflammatory cytokine IL-10 significantly diminished IFN-␥-induced Fas expression, thus showing that IL-10 may play a role in protecting intestinal tissue that is exposed to T-cellinitiated inflammation. In human colonic IELs, culture with anti-FasL antibody significantly recovered cell viability, a finding underlining the importance of FasL in maintaining intestinal tolerance to antigen via apoptotic signals.126 Studies of activation-induced cell death (AICD) mediated via Fas/FasL interaction in IBD have focused on the concept of Fas-mediated apoptosis of enterocytes in disease pathogenesis. FasL-based apoptosis of enterocytes has been shown in several chronic inflammatory diseases, such as celiac disease, UC, pouchitis, and graft versus host disease.127 In patients with UC, a concentration of systemic sFas was significantly lower in active UC than in controls and the number of FasL-containing T cells was significantly

Translational Research April 2007

higher in active UC than in remission UC, non-IBD colitis, and controls, suggesting that Fas-mediated apoptosis of enterocytes is promoted in UC.128 Ueyama129 investigated colonic mucosal specimens from UC patients and found that FasL was expressed in CD3 lymphocytes infiltrating into UC lesions, suggesting that Fas–FasL-induced apoptosis participates in the mucosal damage of UC. Suzuki et al130 have studied Fas/FasL expression on activated colonic T cells of UC patients, as well as the susceptibility of such T cells to AICD, and have reported that CD4⫹ and CD8⫹ T cells in UC mucosa expressing FasL were significantly enhanced, suggesting that T cells in UC are less sensitive to apoptotic signals mediated by Fas. Interestingly, in biopsy specimens from CD patients, increased enterocyte apoptosis was not mediated by the Fas–FasL mechanism, suggesting that the pathophysiological mechanisms in CD versus UC may be differentially regulated.131 Mounting evidence exists in IBD for the presence of a third regulatory pathway in apoptosis involving TGF␤1), Smad7, and NF-␬B. TGF-␤1 belongs to a family of multifunctional cytokines that regulate a variety of immune processes including cell differentiation, proliferation, and apoptosis via non-FasL-dependent pathways. Smad7 is a known TGF-␤1 signaling molecule that mediates TGF-␤1-induced apoptosis in several cell types.132 NF-␬B is a cytoplasmic protein capable of regulating gene transcription and inhibiting lymphocyte apoptosis, and it is up-regulated in IBD.133 Immunologically mediated tissue damage in the gut is associated with increased production of pro-inflammatory cytokines, which activate the transcription factor NF␬BNF-␬B in a variety of different cell types. Stimuli like oxidative stress, cytokines (IL-1, IL-6, and TNF␣), bacteria, and viruses are involved in triggering the release NF-␬BNF-␬B from their inactive cytoplasmatic form to the nucleus.134 Sustained NF-␬B activation is associated with the prevention of Fas-mediated apoptosis leading to prolonged T-cell survival and inflammatory processes in animal models.135 Pretreatment of normal human intestinal LPMC with TGF-␤1 results in a marked suppression of TNF-␣-induced NF-␬B.136 Over-expression or treatment with the Smad7 protein has been shown to induce sensitization of cells to different forms of cell death by inhibiting the survival of NF-␬B factor and by blocking TGF-␤1 signaling.137 CELL ADHESION AND TRAFFICKING OF LEUKOCYTES

A key stage in the inflammatory process in IBD involves the homing of leukocytes from the circulation into the lymphoid tissue (or Peyer’s patches) of the intestine. Leukocyte trafficking involves the flow of naïve and memory lymphocytes through endothelial

Translational Research Volume 149, Number 4

venules where they interact with the endothelium through a weak, rolling interaction. The initial binding is mediated by the interaction of various adhesion molecules with glycosylated ligands and may be enhanced by the presence of chemokines.138 Chemokine receptors expressed on rolling T cells interact with chemokines in the glycocalyx of endothelial cells, triggering adhesion molecules to bind their associated ligands more tightly. This binding of chemokine receptors leads to a cessation of rolling as the leukocyte binds more firmly to the endothelium. As a result of this interaction, the leukocyte is eventually able to extravasate through the endothelium of the blood vessel and migrate into the lamina propria of the intestine. T cells are maintained within the intestinal tissue by additional chemokine signals and adhesive interactions, which may involve binding of adhesion proteins to the extracellular matrix (ECM) or to cellular receptors expressed on cells within the tissue.139 Leukocyte recruitment involves the participation of 3 main classes of adhesion molecules: selectins and their ligands, integrins, and cell adhesion molecule immunoglobulins.140 Selectins are designated as leukocyte (L)-, platelet (P)-, and endothelial (E)-selectins and comprise a family of adhesive receptors that are expressed on L, P, and E. The function of selectins is restricted to the circulatory system in which their synthesis and expression is regulated by cytokines and other inflammatory mediators. Selectins and their carbohydrate-containing mucin-like counterparts play a role in the promotion of inflammatory bowel processes by mediating the exit of leukocytes from the circulation into the gut wall.140 Down-regulation of L-selectin on the plasma membrane may be achieved through the activation of neutrophils,141 whereas the synthesis of E-selectin may be induced directly by cytokines such as IL-1 and TNF-␣ or bacterial lipopolysaccharide.142 E-selectin has been implicated in the pathogenesis of IBD in a study that demonstrated an increase in the expression of E-selectin and circulating soluble E-selectin in active inflamed tissue from intestinal biopsy specimens of IBD patients.143 Point mutations that decrease NF-␬B binding result in diminished cytokine-induced E-selectin expression on cultured endothelial cells (ECs).144 P-selectin, which is expressed not only on platelets but also on the surface of activated ECs after stimulation by cytokines, acts to recruit leukocytes into post-capillary venules and promote the aggregation of platelets with leukocytes.145 P-selectin appears to induce the activation of integrins, which then communicate with other extracellular stimuli to support maximal adhesion of human neutrophils.145 Fagerstam et al reported that patients with IBD in remission had higher basal platelet surface P-selectin expression, suggesting that an exag-

Neuman

179

gerated platelet activity with increased expression of platelet P-selectin and release of cytokines may be involved in increasing susceptibility to gut inflammatory processes.146 Endothelial P-selectin was also found to be elevated in the vicinity of lymphoid aggregates in the intestine and on veins, venules, and capillaries of the inflamed gut in patients with CD and UC.147 In addition to the involvement of selectins in the trafficking of leukocytes, intestinal inflammation in IBD may involve the actions of molecules called integrins, heterodimeric transmembrane proteins that mediate adhesion to various components in the ECM. Overall, 20 different known integrins exist, each of which can be identified by the type of ␤ chain present in its receptor complex. Survival of colonic epithelial cells depends on matrix adhesion and is mediated in part by interactions between ␤1-integrins and components of the ECM.148 Current research into the relation between adhesion molecules and IBD has centered on the ␣4 ␤7 integrin, a molecule that is highly concentrated in gut lymphoid tissue. Abramson et al have demonstrated that T cells expressing ␣4 ␤7 are more likely to produce the Th1 cytokine IFN-␥ than controls, suggesting that ␣4 ␤7 may play an important role in cytokine-mediated immunosurveillance of the gut mucosa.149 Furthermore, ␣4 ␤7 integrin mediates lymphocyte homing to Peyer’s patches and to intestinal lamina propria through the recognition of the mucosal address in cell adhesion molecule-1 (MAdCAM-1) endothelial ligand.150,151 MAdCAM-1 is induced by TNF-␣ and is known to rely on CYP450-derived oxidants for its proper functioning.152 In addition, mucin deficiency in mice leads to inflammation of the colon and contributes to the onset and perpetuation of experimental colitis.153 The functional significance of increased appearance of MAdCAM-1 in IBD is supported by several reports, which show that the neutralization of MAdCAM-1 or its ligand, the ␣4 ␤7 integrin, attenuates inflammation and mucosal damage in animal models of colitis.154,155 Antibodies that recognize ␣4 ␤7 or MAdCAM-1 are able to inhibit lymphocyte migration into Peyer’s patches and the lamina propria156 and block chronic colonic inflammation in murine models.157 Clinically, MAdCAM-1 has been linked to inflammation in CD and in UC, where venular endothelium expressing MAdCAM-1 is increased within the lamina propria of inflamed intestinal tissue.158 Lastly, investigations in the area of endothelial adhesion in IBD have uncovered a role for a class of adhesion components that belong to an immunoglobulin-like superfamily. Some members of this family, such as intercellular adhesion molecule (ICAM)-1 and ICAM-2, vascular cell adhesion molecule-1 (VCAM-1), platelet-endothelial cell adhesion molecule, and MAdCAM-1, are known to par-

180

Neuman

ticipate in cell– cell adhesion between leukocytes and ECs, and may bind to other types of adhesion molecules such as integrins or selectins.159 ICAM-1 is constitutively expressed not only on ECs but also on lymphocytes, monocytes, epithelial cells, and other cells. It can be up-regulated transcriptionally by TNF-␣ and IL-1.160 VCAM-1 is expressed on activated ECs, macrophages, dendritic cells, and fibroblasts. While binding to its ligands, integrin ␣4 ␤4 and ␣4 ␤7 on lymphocytes, monocytes, and eosinophils, VCAM-1 modulates leukocyte adhesion to ECs and migration to sites of inflammation.161 Experimentally, anti-ICAM-1 mAb and antisense oligonucleotide were shown to diminish the clinical severity of inflammation in acute dextran sulphate sodium-induced colitis in rats and mice.162 Remarkable increases in the expression of VCAM-1 have been observed in trinitrobenzene- and polysaccharideinduced colitis in murine models.163 In a murine model of CD, blocking ICAM-1 and VCAM-1 showed a 70% resolution of active inflammation in inflamed intestinal tissue.164 Marked increases in VCAM-1 and ICAM-1 have been observed in platelets from IBD patients,165 and several studies have shown that the serum from patients with UC and CD contains a higher concentration of soluble ICAM-1 and VCAM-1 as compared with controls.166,167 IMMUNE-BASED THERAPIES FOR IBD Anti-TNF therapies. Immunologic therapies have begun to assume a prominent role among newer therapies for the treatment of IBD. Immune-based approaches have included the development of monoclonal antibodies to IL-11,168 IL-2,169 and IL-6;170 but the most successful therapeutic agents in the treatment of IBD have proven to be those antibodies that target the activities of TNF-␣. A variety of biological agents have been used to inhibit TNF-␣ in patients with IBD, including the mouse/human chimeric monoclonal antibody (infliximab), the humanized monoclonal antibody CDP571, the human soluble TNF-␣ p55 receptor (onercept), the human monoclonal antibody D2E7 (adalimumab), the p75 soluble TNF receptor fusion protein (etanercept), and the polyethylene glycol (PEG)ylated anti-TNF-␣ antibody fragment CDP-870. Among these, infliximab (formerly cA2) and CDP571 have shown the most promise, particularly in CD. Infliximab therapy has been demonstrated to be effective at a dosage of 5 mg/kg in inducing and maintaining response in patients with moderate to severe CD that is refractory to conventional therapy.171,172 Randomized trials have also demonstrated some degree of effectiveness of infliximab in the closure of fistulas in CD patients173,174 and in the treatment of refractory UC.175 Infliximab appears to exert its therapeutic effects by

Translational Research April 2007

means of neutralizing soluble and transmembrane TNF-␣, inducing caspase-dependent monocyte apoptosis, and lysing TNF-␣-producing cells by means of antibody-dependent cytotoxicity.176 Elevated levels of circulating TNF-␣ are associated with a lack of response to infliximab, a finding that could be useful in identifying cytokine markers for those patients that would benefit from treatment.177 Placebo-controlled trials with the humanized monoclonal antibody CDP571 have shown a clinical response in CD patients at doses ranging from 5 to 20 mg/kg.178,179 A preliminary uncontrolled pilot study has suggested that CDP571 may also be of benefit in patients with active UC.180 A controlled pilot study undertaken to investigate the recombinant TNF-␣-binding protein onercept has reported clinical remission of CD. The results are based on CDAI scores in 18% of patients receiving onercept 11.7 mg compared with 67% of patients receiving CDP571.181 A large placebo-controlled phase II study of onercept is currently underway. Safety problems with anti-TNF treatment involve immunogenicity, loss of response, and serum sickness-like delayed infusion reactions.182 Anti-integrin treatment. In addition to anti-TNF therapy, there has been much current interest in the drug natalizumab (Antegren), a recombinant monoclonal antibody to the ␣4 integrin molecule that has been used experimentally in the treatment of several inflammatory disorders of the brain and gut. The humanized monoclonal antibody is the first ␣4 integrin antagonist in a novel class of biological agents referred to as selective adhesion molecule inhibitors. Nataluzimab is thought to disrupt VCAM-1/␣4 ␤1 and MadCAM-1/␣4 ␤7 interactions, resulting in a reduction of lymphocyte migration and attenuation of the release of cytokines and other substances that cause tissue injury.183 A randomized, controlled clinical trial of natalizumab in CD patients demonstrated a reduction by at least 70 points on the CDAI, as well as a significant improvement in the health-related quality of life and levels of C-reactive proteins.184,185 Recombinant IL-10. Most recently, the results of subcutaneous toxicity studies and preclinical investigations in animal models have suggested the therapeutic potential of IL-10 (Tenovil), a novel preparation for use in the treatment of IBD.186 A general activation of IL-10-producing CD4⫹ T cells along the intestine of UC patients has been proposed based on the biological consequences of a local environment of elevated IL-10.101 In a randomized, placebo-controlled study, 23.5% of CD patients treated with 5 micro/kg rhuIL-10 experienced clinical remission compared with 0% of controls.187 Colombel et al have demonstrated that IL-10 (Tenovil) treatment for 12 consecutive weeks in patients with CD after intestinal surgical resection was safe and well tolerated, although no evi-

Translational Research Volume 149, Number 4

dence of prevention of endoscopic recurrence of CD was observed.188 Administration of recombinant human IL-10 by intravenous or subcutaneous routes has been discontinued because of lack of efficacy in controlled trials. The future potential of IL-10 therapy may hinge on the development of new methods for mucosal delivery, such as the use of genetically modified bacteria, gelatine microspheres, and adenoviral IL-10-encoding vectors.189 In addition, other avenues, such as peroxisome proliferatoractivated receptor gamma agonists, may reduce IL-6, IL1-␤, and TNF-␣ RNA in colonic epithelial mucose.190,191 All these potential therapies are making their signature in the field. CONCLUSION

Experimental studies in IBD point to an excessive Th1 response to antigenic stimulus leading to increased levels of various cytokines, the most crucial of which are IL-1, IL-6, TNF-␣, IFN-␥, IL-12, and IL-18. Although the initial purpose of the inflammatory response is to provide protection against the invasion of a foreign antigen, in IBD, the immune response becomes dysregulated, resulting in damage to host intestinal tissue. The expression of pro-inflammatory cytokines in the intestinal mucosa from IBD patients is markedly enhanced, highlighting the polarization of T-cell activity that is characteristic of the defective inflammatory response. Activation of cytokines, disruption of leukocyte adhesion, and alterations in apoptotic pathways are components of the inflammatory process that allow one to understand the basic immunologic mechanisms underlying the pathology of IBD. Already, an understanding of the immunologic basis of IBD has led to the development of effective therapies, such as daclizumab, infliximab, CDP571, and natalizumab. Further elucidation of the immunological pathways underlying the pathogenesis of IBD will contribute to the development of novel targets for medical therapies in the near future.62 This paper was presented at the 7th International Symposium on Cytokines and Chemokines (Montréal, Québec, Canada, 7–9 September, 2005). Dr. Manuela G. Neuman, scientific organizer of the symposium, is grateful for the financial support given by the Institute of Infection and Immunity of Canadian Institutes of Health Research, and by the National Institute on Alcohol Abuse and Alcoholism, National Institute of Health, USA. REFERENCES

1. Loftus EV Jr. Clinical epidemiology of inflammatory bowel disease: incidence, prevalence, and environmental influences. Gastroenterol 2004;126:1504 –17. 2. Podolsky DK. The current future understanding of inflammatory bowel disease. Best Pract Res Clin Gastroenterol 2002;16: 933– 43. 3. Kakazu T, Hara J, Matsumoto T, Nakamura S, Oshitani N, Arakawa T, et al. Type 1 T-helper cell predominance in granulomas of Crohn’s disease. Am J Gastroenterol 1999;94: 2149 –55.

Neuman

181

4. Hendrickson BA, Gokhale R, Cho JH. Clinical aspects and pathophysiology of inflammatory bowel disease. Clin Microbiol Rev 2002;15:79 –94. 5. Blumberg RS, Saubermann LJ, Strober W. Animal models of mucosal inflammation and their relation to human inflammatory bowel disease. Curr Opin Immunol 1999;11:648 –56. 6. Amasheh S, Barmeyer C, Koch CS, Tavalali S, Mankerz J, Epple HJ, et al. Cytokine-dependent transcriptional down-regulation of epithelial sodium channel in ulcerative colitis. Gastroenterol 2004;126:1711–20. 7. Itzkowitz SH, Harpaz N. Diagnosis and management of dysplasia in patients with inflammatory bowel diseases. Gastroenterol 2004;126:1634 – 48. 8. Brookes MJ, Green JR. Maintenance of remission in Crohn’s disease: current and emerging therapeutic options. Drugs 2004; 64:1069 – 89. 9. Karlinger K, Gyorke T, Mako E, Mester A, Tarjan Z. The epidemiology and the pathogenesis of inflammatory bowel disease. Eur J Radiol 2000;35:154 – 67. 10. Yu Y, Sitaraman S, Gewirtz AT. Intestinal epithelial cell regulation of mucosal inflammation. Immunol Res 2004;29:55– 68. 11. Fiocchi C. The immune system in inflammatory bowel disease. Acta Gastroenterol Belg 1997;60:156 – 62. 12. Singh B, Read S, Asseman C, Malstrom V, Mottet C, Stephenes LA, et al. Control of intestinal inflammation by regulatory T cells. Immunol Rev 2001;182:190 –200. 13. Muller S, Lory J, Corazza N, Griffits GM, Z’graggen K, Mazuchelli M, et al. Activated CD4⫹ and CD8⫹ cytotoxic cells are present in increased numbers in the intestinal mucosa from patients with active inflammatory bowel disease. Am J Pathol 1998;152:261– 8. 14. Mahida YR, Rolfe V. Host-bacterial interactions in inflammatory bowel disease. Clin Sci (London) 2004;23:15–23. 15. Lu J, Wang A, Ansari S, Hershberg RM, McKey DM. Colonic bacterial superantigens evoke an inflammatory response and exaggerate disease in mice recovering from colitis. Gastroenterol 2003;125:1785–95. 16. Okazaki K, Morita M, Nishimori I, Sano S, Toyonaga M, Nakazawa Y, et al. Major histocompatibility antigen-restricted cytotoxicity in inflammatory bowel disease. Gastroenterol 1993;104:384 –91. 17. Kanauchi O, Mitsuyama K, Araki Y, Andoh A. Modification of intestinal flora in the treatment of inflammatory bowel disease. Curr Pharm Des 2003;9:333– 46. 18. Strober W, Fuss IJ, Blumberg RS. The immunology of mucosal models of inflammation.Annu Rev Immunol 2002;20:495–549. 19. Hugot JP, Alberti C, Berrebi D, Bingen E, Cezard JP. Crohn’s disease: the cold chain hypothesis. Lancet 2003;362:2012–5. 20. Nakazawa A, Dotan I, Brimnes J, Allez M, Shao L, Tsushima F, et al. The expression and function of costimulatory molecules B7H and B7-H1 on colonic epithelial cells. Gastroenterol 2004; 126:1347–57. 21. Biancone L, Monteleone I, Del Vecchio Blanco G, Vavassori P, Pallone F. Resident bacterial flora and immune system. Dig Liver Dis 2002;34(suppl 2):S37– 43. 22. Iellem A, Colantonio L, D’Ambrosio D. Skin-versus gutskewed homing receptor expression and intrinsic CCR4 expression on human peripheral blood CD4⫹CD25⫹ suppressor T cells. Eur J Immunol 2003;33:1488 –96. 23. Barbier M, Vidal H, Desreumaux P, Dubuqoy L, Boureille A, Colombel J, et al. Overexpression of leptin mRNA in mesenteric adipose tissue in inflammatory bowel diseases. Gastroenterol Clin Biol 2003;27:987–91.

182

Translational Research April 2007

Neuman

24. Jacobson-Brown P, Neuman MG. Colorectal polyposis and immune-based therapies. Can J Gastroenterol 2004,18:239 – 49. 25. Di Sabatino A, Ciccocioppo R, Luinetti O, Ricevutti L, Morera L, Cipone MG, et al. Increased enterocyte apoptosis in inflamed areas of Crohn’s disease. Dis Colon Rectum 2003;46:1498 – 507. 26. Prasad KV, Prabhakar BS. Apoptosis and autoimmune disorders. Autoimmunity 2003;36:323–30. 27. Rieux-Laucat F, Le Deist F, Fischer A. Autoimmune lymphoproliferative syndromes: genetic defects of apoptosis pathways. Cell Death Differ 2003;10:124 –33. 28. Ciccocioppo R, Di Sabatino A, Luinetti O, Rossi M, Cifone MG, Corazza GR. Small bowel enterocyte apoptosis and proliferation are increased in the elderly. Gerontol 2002;48:204 – 8. 29. Mariani P, Bachetoni A, D’Alessandro M, Lomanto D, Mazzochi P, Sperantza V. Effector Th-1 cells with cytotoxic function in the intestinal lamina propria of patients with Crohn’s disease. Dig Dis Sci 2000;45:2029 –35. 30. Jung HC, Eckmann L, Yang SK, Panja A, Fierer J, MorzickaWroblewska A, et al. A distinct array of proinflammatory cytokines is expressed in human colon epithelial cells in response to bacterial invasion. J Clin Invest 1995;95:55– 65. 31. Mahida YR. The key role of macrophages in the immunopathogenesis of inflammatory bowel disease. Inflamm Bowel Dis 2000;6:21–33. 32. Weinstein DL, O’Neill BL, Metcalf ES. Salmonella typhi stimulation of human intestinal epithelial cells induces secretion of epithelial cell-derived interleukin-6. Infect Immun 1997;65: 395– 404. 33. Lotz M, Gutle D, Walther S, Menard S, Bogdan C, Hornef MW. Postnatal acquisition of endotoxin tolerance in intestinal epithelial cells. J Exp Med 2006;17:973– 84. 34. Reimund JM, Wittersheim C, Dumont S, Muller CD, Kenney JS, Baumann R, et al. Increased production of tumour necrosis factor-alpha interleukin-1 beta, and interleukin-6 by morphologically normal intestinal biopsies from patients with Crohn’s disease. Gut 1996;39:684 –9. 35. Reinecker HC, Steffen M, Witthoeft T, Pflueger I, Schreiber S, MacDermott RP, et al. Enhanced secretion of tumour necrosis factor-alpha, IL-6, and IL-1 beta by isolated lamina propria mononuclear cells from patients with ulcerative colitis and Crohn’s disease. Clin Exp Immunol 1993;94:174 – 81. 36. Camoglio L, Te Velde AA, Tigges AJ, Das PK, Van Deventer SG. Altered expression of interferon-gamma and interleukin-4 in inflammatory bowel disease. Inflamm Bowel Dis 1998;4: 285–90. 37. Sawa Y, Oshitani N, Adachi K, Higuchi K, Matsumoto T, Arakawa T. Comprehensive analysis of intestinal cytokine messenger RNA profile by real-time quantitative polymerase chain reaction in patients with inflammatory bowel disease. Int J Mol Med 2003;11:175–9. 38. Papadakis KA. Chemokines in inflammatory bowel disease. Curr Allergy Asthma Rep 2004;4:83–9. 39. Guimbaud R, Bertrand V, Chauvelot-Moachon L, Quartier G, Vidon N, Giroud JP, et al. Network of inflammatory cytokines and correlation with disease activity in ulcerative colitis. Am J Gastroenterol 1998;93:2397– 404. 40. Mosmann TR, Sad S. The expanding universe of T-cell subsets: Th1, Th2 and more. Immunol Today 1996;17:138 – 46. 41. Garg AK, Aggarwal BB. Reactive oxygen intermediates in TNF signaling. Mol Immunol 2002;39:509 –17. 42. Brandonisio O, Panaro MA, Sisto M, Leogrande D, Aquafredda A, Spinelli R, et al. Nitric oxide production by Leishmania-

43.

44.

45. 46.

47.

48.

49.

50. 51.

52.

53.

54.

55.

56.

57.

58.

59.

60.

infected macrophages and modulation by cytokines and prostaglandins. Parassitologia 2001;43(suppl 1):1– 6. Nassif A, Longo WE, Mazuski JE, Vernava AM, Kaminski DL. Role of cytokines and platelet-activating factor in inflammatory bowel disease. Implications for therapy. Dis Colon Rectum 1996;39:217–23. Rogler G, Brand K, Vogl D, Page S, Hoffmeister R, Andus T, et al. Nuclear factor kappaB is activated in macrophages and epithelial cells of inflamed intestinal mucosa. Gastroenterol 1998;115:357– 69. Baumann H, Gauldie J. The acute phase response. Immunol Today 1994;15:74 – 80. Barbara JA, Van Ostade X, Lopez A. Tumour necrosis factoralpha (TNF-␣): the good, the bad and potentially very effective. Immunol Cell Biol 1996;74:434 – 43. Shetty A, Forbes A. Pharmacogenomics of response to antitumor necrosis factor therapy in patients with Crohn’s disease. Am J Pharmacogenom 2002;2:215–21. Bauditz J, Wedel S, Lochs H. Thalidomide reduces tumour necrosis factor alpha and interleukin 12 production in patients with chronic active Crohn’s disease. Gut 2002;50:196 –200. Brierley MM, Fish EN. Review: IFN-alpha/beta receptor interactions to biologic outcomes: understanding the circuitry. J Interferon Cytokine Res 2002;22:835– 45. Neuman MG. Signaling for inflammation and repair in inflammatory bowel disease. Rom J Gastroenterol 2004;13:309 –16. Bamias G, Martin C 3rd, Marini M, Huang S, Mishina M, Ross WG, et al. Expression, localization, and functional activity of TL1A, a novel Th1-polarizing cytokine in inflammatory bowel disease. J Immunol 2003 1;171:4868 –74. Uhlig HH, McKenzie BS, Hue S, Thompson C, Joyce-Shaikh B, Stepankova R, et al. Differential activity of IL-12 and IL-23 in mucosal and systemic innate immune pathology. Immunity 2006;25:309 –18. Targan SR, Hanauer SB, van Deventer SJ, Mayer L, Present DH, Braakman T, et al. A short-term study of chimeric monoclonal antibody cA2 to tumor necrosis factor alpha for Crohn’s disease. Crohn’s Disease cA2 Study Group. N Engl J Med 1997;337:1029 –35. Baert FJ, Rutgeerts PR. Anti-TNF strategies in Crohn’s disease: mechanisms, clinical effects, indications. Int J Colorectal Dis 1999;14:47–51. Neurath, MF, Fuss I, Pasparakis M, Alexopoulou L, Haralambous S, Meyer zum Buschenfelde KH, et al. Predominant pathogenic role of tumor necrosis factor in experimental colitis in mice. Eur J Immunol 1997;27:1743–50. Strober W, Kelsall B, Fuss I, Marth T, Ludviksson B, Ehrhardt R, et al. Reciprocal IFN- and TGF- ␤ responses regulate the occurrence of mucosal inflammation. Immunol Today 1997;18: 61– 4. Breese EJ, Michie CA, Nicholls SW, Murch SH, Williams CB, Domizio P, et al. Tumor necrosis factor alpha-producing cells in the intestinal mucosa of children with inflammatory bowel disease. Gastroenterol 1994;106:1455– 66. Maeda M, Watanabe N, Neda H, Yamauchi N, Okamoto T, Sasaki H, et al. Serum tumor necrosis factor activity in inflammatory bowel disease. Immunopharmacol Immunotoxicol 1992; 14:451– 61. Reimund JM, Wittersheim C, Dumont S, Muller CD, Baumann R, Poindron P, et al. Mucosal inflammatory cytokine production by intestinal biopsies in patients with ulcerative colitis and Crohn’s disease. J Clin Immunol 1996;16:144 –50. Sategna-Guidetti C, Pulitano R, Fenoglio L, Bologna E, Manes M, Camussi G. Tumor necrosis factor/cachectin in Crohn’s

Translational Research Volume 149, Number 4

61.

62.

63. 64.

65.

66.

67.

68.

69.

70.

71. 72.

73.

74.

75.

76.

77.

78.

disease. Relation of serum concentration to disease activity. Recenti Prog Med 1993;84:93–9. Murch SH, Lamkin VA, Savage MO, Walker-Smith JA, MacDonald T. Serum concentrations of tumour necrosis factor alpha in childhood chronic inflammatory bowel disease. Gut 1991;32: 913–7. Ligumsky M, Simon PL, Karmeli F, Rachmilewitz D. Role of interleukin 1 in inflammatory bowel disease— enhanced production during active disease. Gut 1990;31:686 –9. Dinarello CA. The IL-1 family and inflammatory diseases. Clin Exp Rheumatol 2002;20(suppl 27):S1–13. Dinarello CA, Thompson RC. Blocking IL-1: interleukin 1 receptor antagonist in vivo andin vitro. Immunol Today 1991; 12:404 –10. Ashwood P, Harvey R, Verjee T, Wolstencroft R, Thompson RP, Powell JJ. Functional interactions between mucosal IL-1, IL-ra and TGF-beta 1 in ulcerative colitis. Inflamm Res 2004; 53:53–9. Casini-Raggi V, Kam L, Chong YJ, Fiocchi C, Pizarro TT, Cominelli F. Mucosal imbalance of IL-1 and IL-1 receptor antagonist in inflammatory bowel disease. A novel mechanism of chronic intestinal inflammation. J Immunol 1995;154: 2434 – 40. Louis E, Ribbens C, Godon A, Franchimont D, De Groote D, Hardy N, et al. Increased production of matrix metalloproteinase-3 and tissue inhibitor of metalloproteinase-1 by inflamed mucosa in inflammatory bowel disease. Clin Exp Immunol 2000;120:241– 6. Dionne S, D’Agata ID, Hiscott J, Vanounou T, Seidman EG. Colonic explant production of IL-1and its receptor antagonist is imbalanced in inflammatory bowel disease (IBD). Clin Exp Immunol 1998;112:435– 42. Cominelli F, Pizarro TT. Interleukin-1 and interleukin-1 receptor antagonist in inflammatory bowel disease. Aliment Pharmacol Ther 1996;10(suppl 2):49 –53. McAlindon ME, Hawkey CJ, Mahida YR. Expression of interleukin 1 beta and interleukin 1 beta converting enzyme by intestinal macrophages in health and inflammatory bowel disease. Gut 1998;42:214 –9. Concha NO, Abdel-Meguid SS. Controlling apoptosis by inhibition of caspases. Curr Med Chem 2002;9:713–26. Jones SA, Butler RN, Sanderson IR, Wilson JW. The effect of specific caspase inhibitors on TNF-alpha and butyrate-induced apoptosis of intestinal epithelial cells. Exp Cell Res 2004;292: 29 –39. Nielsen OH, Vainer B, Madsen SM, Seidelin JB, Heegaard NH. Established and emerging biological activity markers of inflammatory bowel disease. Am J Gastroenterol 2000;95:359 – 67. Mitsuyama K, Toyonaga A, Sasaki E, Ishida O, Ikeda H, Tsuruta O, et al. Soluble interleukin-6 receptors in inflammatory bowel disease: relation to circulating interleukin-6. Gut 1995;36:45–9. Jones SA, Horiuchi S, Topley N, Yamamoto N, Fuller GM. The soluble interleukin 6 receptor: mechanisms of production and implications in disease. FASEB J 2001;15:43–58. Kallen KJ. The role of transsignalling via the agonistic soluble IL-6 receptor in human diseases. Biochim Biophys Acta 2002; 1592:323– 43. Yamamoto M, Yoshizaki K, Kishimoto T, Ito H. IL-6 is required for the development of Th1 cell-mediated murine colitis. J Immunol 2000;164:4878 – 82. Atreya R, Mudter J, Finotto S, Mullberg J, Jostock T, Wirtz S, et al. Blockade of interleukin 6 trans signaling suppresses T-cell resistance against apoptosis in chronic intestinal inflammation:

Neuman

79.

80.

81.

82.

83.

84.

85.

86.

87.

88.

89.

90.

91.

92.

93.

183

evidence in Crohn disease and experimental colitis in vivo. Nat Med 2000;6:583– 8. Reinisch W, Gasche C, Tillinger W, Wyatt J, Lichtenberger C, Willheim M, et al. Clinical relevance of serum interleukin-6 in Crohn’s disease: single point measurements, therapy monitoring, and prediction of clinical relapse. Am J Gastroenterol 1999;94:2156 – 64. Van Kemseke C, Belaiche J, Louis E. Frequently relapsing Crohn’s disease is characterized by persistent elevation in interleukin-6 and soluble interleukin-2 receptor serum levels during remission. Int J Colorectal Dis 2000;15:206 –10. Lebel-Binay S, Berger A, Zinzindohoue F, Cugnenc P, Thiounn N, Fridman WH, et al. Interleukin-18: biological properties and clinical implications. Eur Cytokine Network 2000;11:15–26. Pizarro TT, Michie MH, Bentz M, Woraratanadharm J, Smith MF Jr, Foley E, et al. IL-18, a novel immunoregulatory cytokine, is up-regulated in Crohn’s disease: expression and localization in intestinal mucosal cells. J Immunol 1999;162: 6829 –35. Pages F, Lazar V, Berger A, Danel C, Lebel-Binay S, Zinzindohoue F, et al. Analysis of interleukin-18, interleukin-1 converting enzyme (ICE) and interleukin-18-related cytokines in Crohn’s disease lesions. Eur Cytokine Network 2001;12:97– 104. Maerten P, Shen C, Colpaert S, Liu Z, Bullens DA, van Assche G, et al. Involvement of interleukin 18 in Crohn’s disease: evidence from in vitro analysis of human gut inflammatory cells and from experimental colitis models. Clin Exp Immunol 2004; 135:310 –7. Corbaz A, ten Hove T, Herren S, Graber P, Schwartsburd B, Belzer I, et al. IL-18-binding protein expression by endothelial cells and macrophages is up-regulated during active Crohn’s disease. J Immunol 2002;168:3608 –16. Kanai T, Watanabe M, Okazawa A, Sato T, Yamazaki M, Okamoto S, et al. Macrophage-derived IL-18-mediated intestinal inflammation in the murine model of Crohn’s disease. Gastroenterol 2001;121:875– 88. Okazawa A, Kanai T, Nakamaru K, Sato T, Inoue N, Ogata H, et al. Human intestinal epithelial cell-derived interleukin (IL)18, along with IL-2, IL-7 and IL-15, is a potent synergistic factor for the proliferation of intraepithelial lymphocytes. Clin Exp Immunol 2004;136:269 –76. Takeda K, Tsutsui H, Yoshimoto T, Adachi O, Yoshida N, Kishimoto T, et al. Defective NK cell activity and Th1 response in IL-18-deficient mice. Immunity 1998;8:383–90. Wei XQ, Leung BP, Niedbala W, Piedrafita D, Feng GJ, Sweet M, et al. Altered immune responses and susceptibility to Leishmania major and Staphylococcus aureus infection in IL-18deficient mice. J Immunol 1999;163:2821– 8. Okamura H, Kashiwamura S, Tsutsui H, Yoshimoto T, Nakanishi K. Regulation of interferon-gamma production by IL-12 and IL-18. Curr Opin Immunol 1998;10:259 – 64. Micallef MJ, Tanimoto T, Kohno K, Ikegami H, Kurimoto M. Interleukin 18 induces a synergistic enhancement of interferon gamma production in mixed murine spleen cell-tumor cell cultures: role of endogenous interleukin 12. Cancer Detect Prev 2000;24:234 – 43. Nakanishi K, Yoshimoto T, Tsutsui H, Okamura H. Interleukin-18 is a unique cytokine that stimulates both Th1 and Th2 responses depending on its cytokine milieu. Cytokine Growth Factor Rev 2001;12:53–72. Trinchieri G. Interleukin-12 and the regulation of innate resistance and adaptive immunity. Nat Rev Immunol 2003;3: 133– 46.

184

Neuman

94. Parronchi P, Romagnani P, Annunziato F, Sampognaro S, Becchio A, Giannarini L, et al. Type 1 T-helper cell predominance and interleukin-12 expression in the gut of patients with Crohn’s disease. Am J Pathol 1997;150:823–32. 95. Berrebi D, Languepin J, Ferkdadji L, Foussat A, De Lagausie P, Paris R, et al. Cytokines, chemokine receptors, and homing molecule distribution in the rectum and stomach of pediatric patients with ulcerative colitis. J Pediatr Gastroenterol Nutr 2003;37:300 – 8. 96. Fiorentino DF, Bond MW, Mosmann TR. Two types of mouse T helper cell. Th2 clones secrete a factor that inhibits cytokine production by Th1 clones. J Exp Med 1989;170:2081–95. 97. Kuhn R, Lohler J, Rennick D, Rajewsky K, Muller W. Interleukin-10-deficient mice develop chronic enterocolitis. Cell 1993;75:263–74. 98. Rennick DM, Fort MM. Lessons from genetically engineered animal models. IL-10-deficient (IL-10(-/-) mice and intestinal inflammation. Am J Physiol Gastrointest Liver Physiol 2000; 278:G829 –33. 99. Kato S, Hokari R, Matsuzaki K, Iwai A, Kawaguchi A, Nagao S, et al. Amelioration of murine experimental colitis by inhibition of mucosal addressin cell adhesion molecule-1. J Pharmacol Exp Ther 2000;295:183–9. 100. Schreiber S, Heinig T, Thiele HG, Raedler A. Immunoregulatory role of interleukin 10 in patients with inflammatory bowel disease. Gastroenterol 1995;108:1434 – 44. 101. Melgar S, Yeung MM, Bas A, Forsberg G, Suhr O, Oberg A, et al. Over-expression of interleukin 10 in mucosal T cells of patients with active ulcerative colitis. Clin Exp Immunol 2003; 134:127–37. 102. Rogler G, Andus T. Cytokines in inflammatory bowel disease. World J Surg 1998;22:382–92. 103. Iijima H, Takahashi I, Kishi D, Kim JK, Kawano S, Hori M, et al. Alteration of interleukin 4 production results in the inhibition of T helper type 2 cell-dominated inflammatory bowel disease in T cell receptor alpha chain-deficient mice. J Exp Med 1999;190:607–15. 104. Lehn M, Weiser WY, Engelhorn S, Gillis S, Remold HG. IL-4 inhibits H2O2 production and anti-leishmanial capacity of human cultured monocytes mediated by IFN-gamma. J Immunol 1989;143:3020 – 4. 105. Crawford RM, Finbloom DS, Ohara J, Paul WE, Meltzer MS. B cell stimulatory factor-1 (interleukin 4) activates macrophages for increased tumoricidal activity and expression of Ia antigens. J Immunol 1987;139:135– 41. 106. Jansen JH, Wientjens GJ, Fibbe WE, Willemze R, KluinNelemans HC. Inhibition of human macrophage colony formation by interleukin 4. J Exp Med 1989;170:577– 82. 107. Griga T, Hebler U, Voigt E, Tromm A, May B. Interleukin-4 inhibits the increased production of vascular endothelial growth factor by peripheral blood mononuclear cells in patients with inflammatory bowel disease. Hepatogastroenterol 2000;47: 1604 –7. 108. Marek A, Brodzicki J, Liberek A, Korzon M. TGF-beta (transforming growth factor-beta) in chronic inflammatory conditions—a new diagnostic and prognostic marker? Med Sci Monit 2002;8:RA145–51. 109. Del Zotto B, Mumolo G, Pronio AM, Montesani C, Tersigni R, Boirivant M, et al. TGF-beta1 production in inflammatory bowel disease: differing production patterns in Crohn’s disease and ulcerative colitis. Clin Exp Immunol 2003;134:120 – 6. 110. Beck PL, Podolsky DK. Growth factors in inflammatory bowel disease. Inflamm Bowel Dis 1999;5:44 – 60.

Translational Research April 2007

111. Kanazawa S, Tsunoda T, Onuma E, Majima T, Kagiyama M, Kikuchi K. VEGF, basic-FGF, and TGF-beta in Crohn’s disease and ulcerative colitis: a novel mechanism of chronic intestinal inflammation. Am J Gastroenterol 2001;96:822– 8. 112. Lawrance IC, Maxwell L, Doe W. Inflammation location, but not type, determines the increase in TGF-beta1 and IGF-1 expression and collagen deposition in IBD intestine. Inflamm Bowel Dis 2001;7:16 –26. 113. Ina K, Itoh J, Fukushima K, Kusugami K, Yamaguchi T, Kyokane K, et al. Resistance of Crohn’s disease T cells to multiple apoptotic signals is associated with a Bcl-2/Bax mucosal imbalance. J Immunol 1999;163:1081–90. 114. Aggarwal S, Gupta S. Increased apoptosis of T cell subsets in aging humans: altered expression of Fas (CD95), Fas ligand, Bcl-2, and Bax. J Immunol 1998;160:1627–37. 115. Itoh J, de La Motte C, Strong SA, Levine AD, Fiocchi C. Decreased Bax expression by mucosal T cells favours resistance to apoptosis in Crohn’s disease. Gut 2001;49:35– 41. 116. Iimura M, Nakamura T, Shinozaki S, Iizuka B, Inoue Y, Suzuki S, et al. Bax is downregulated in inflamed colonic mucosa of ulcerative colitis. Gut 2000;47:228 –35. 117. Tang Y, Swartz-Basile DA, Swietlicki EA, Yi L, Rubin DC, Levin MS. Bax is required for resection-induced changes in apoptosis, proliferation, and members of the extrinsic cell death pathways. Gastroenterol 2004;126:220 –30. 118. Harnois C, Demers MJ, Bouchard V, Vallee K, Gagne D, Fujita N, et al. Human intestinal epithelial crypt cell survival and death: complex modulations of Bcl-2 homologs by Fak, PI3-K/ Akt-1, MEK/Erk, and p38 signaling pathways. J Cell Physiol 2004;198:209 –22. 119. Edwards SW, Derouet M, Howse M, Moots RJ. Regulation of neutrophil apoptosis by Mcl-1. Biochem Soc Trans 2004;32: 489 –92. 120. Nagata S. Fas ligand-induced apoptosis. Annu Rev Genet 1999; 33:29 –55. 121. De Maria R, Boirivant M, Cifone MG, Roncaioli P, Hahne M, Tschopp J, et al. Functional expression of Fas and Fas ligand on human gut lamina propria T lymphocytes. A potential role for the acidic sphingomyelinase pathway in normal immunoregulation. J Clin Invest 1996;97:316 –22. 122. French LE, Tschopp J. Constitutive Fas ligand expression in several non-lymphoid mouse tissues: implications for immuneprotection and cell turnover. Behring Inst Mitt 1996;97: 156 – 60. 123. Kaser A, Nagata S, Tilg H. Interferon alpha augments activation-induced T cell death by upregulation of Fas (CD95/APO-1) and Fas ligand expression. Cytokine 1999;11:736 – 43. 124. Suda T, Hashimoto H, Tanaka M, Ochi T, Nagata S. Membrane Fas ligand kills human peripheral blood T lymphocytes, and soluble Fas ligand blocks the killing. J Exp Med 1997;186: 2045–50. 125. Ayroldi E, Zollo O, Cannarile L, D’Adamio F, Grohmann U, Delfino DV, et al. Interleukin-6 (IL-6) prevents activationinduced cell death: IL-2-independent inhibition of Fas/fasL expression and cell death. Blood 1998;92:4212–19. 126. Hongo T, Morimoto Y, Iwagaki H, Kobashi K, Yoshii M, Urushihara N, et al. Functional expression of Fas and Fas ligand on human colonic intraepithelial T lymphocytes. J Int Med Res 2000;28:132– 42. 127. Ciccocioppo R, Di Sabatino A, Gasbarrini G, Corazza GR. Apoptosis and gastrointestinal tract. Ital J Gastroenterol Hepatol 1999;31:162–72. 128. Yukawa M, Iizuka M, Horie Y, Yoneyama K, Shirasaka T, Itoh H, et al. Systemic and local evidence of increased Fas-mediated

Translational Research Volume 149, Number 4

129.

130.

131. 132.

133.

134. 135.

136.

137.

138.

139.

140.

141.

142.

143.

144.

apoptosis in ulcerative colitis. Int J Colorectal Dis 2002;17: 70 –76. Ueyama H, Kiyohara T, Sawada N, Isozaki K, Kitamura S, Kondo S, et al. High Fas ligand expression on lymphocytes in lesions of ulcerative colitis. Gut 1998;43:48 –55. Suzuki A, Sugimura K, Ohtsuka K, Hasegawa K, Suzuki K, Ishizuka K, et al. Fas/Fas ligand expression and characteristics of primed CD45RO⫹ T cells in the inflamed mucosa of ulcerative colitis. Scand J Gastroenterol 2000;35:1278 – 83. Nagata S, Goldstein P. The Fas death factor. Science 1995;267: 1449 –55. Edlund S, Bu S, Schuster N, Aspenstrom P, Heuchel R, Heldin NE, et al. Transforming growth factor-beta1 (TGF-beta)induced apoptosis of prostate cancer cells involves Smad7dependent activation of p38 by TGF-beta-activated kinase 1 and mitogen-activated protein kinase kinase 3. Mol Biol Cell 2003; 14:529 – 44. Klein W, Tromm A, Folwaczny C, Hagedorn M, Duerig N, Epplen JT, et al. A polymorphism of the NFKBIA gene is associated with Crohn’s disease patients lacking a predisposing allele of the CARD15 gene. Int J Colorectal Dis 2004;19: 153– 6. Schreiber S, Nikolaus S, Hampe J. Activation of nuclear factor kappa B inflammatory bowel disease. Gut 1998;42:477– 84. van der Woude CJ, Kleibeuker JH, Jansen PL, Moshage H. Chronic inflammation, apoptosis and pre-malignant lesions in the gastro-intestinal tract. Apoptosis 2004;9:123–30. Monteleone G, Mann J, Monteleone I, Vavassori P, Bremner R, Fantini M, et al. A failure of transforming growth factor-beta1 negative regulation maintains sustained NF-kappa B activation in gut inflammation. J Biol Chem 2004;279:3925–32. Lallemand F, Mazars A, Prunier C, Bertrand F, Kornprost M, Gallea S, et al. Smad7 inhibits the survival nuclear factor kappa B and potentiates apoptosis in epithelial cells. Oncogene 2001; 20:879 – 84. Grabovsky V, Feigelson S, Chen C, Bleijs DA, Peled A, Cinamon G, et al. Subsecond induction of alpha4 integrin clustering by immobilized chemokines stimulates leukocyte tethering and rolling on endothelial vascular cell adhesion molecule 1 under flow conditions. J Exp Med 2000;192:495–506. Strauch UG, Mueller RC, Li XY, Cernadas M, Higgins JM, Binion DG, et al. Integrin alpha E(CD103)beta 7 mediates adhesion to intestinal microvascular endothelial cell lines via an E-cadherin-independent interaction. J Immunol 2001;166: 3506 –14. Kishimoto TK, Jutila MA, Butcher EC. Identification of a human peripheral lymph node homing receptor: a rapidly downregulated adhesion molecule. Proc Natl Acad Sci USA 1990; 87:2244 – 8. Fries JW, Williams AJ, Atkins RC, Newman W, Lipscomb MF, Collins T. Expression of VCAM-1 and E-selectin in an in vivo model of endothelial activation. Am J Pathol 1993;143:725–37. Bhatti M, Chapman P, Peters M, Haskard D, Hodgson HJ. Visualising E-selectin in the detection and evaluation of inflammatory bowel disease. Gut 1998;43:40 –7. Essani NA, McGuire GM, Manning AM, Jaeschke H. Endotoxin-induced activation of the nuclear transcription factor kappa B and expression of E-selectin messenger RNA in hepatocytes, Kupffer cells, and endothelial cells in vivo. J Immunol 1996;156:2956 – 63. Kunkel EJ, Jung U, Bullard DC, Norman KE, Wolitzky BA, Vestweber D, et al. Absence of trauma-induced leukocyte rolling in mice deficient in both P-selectin and intercellular adhesion molecule 1. J Exp Med 1996;183:57– 65.

Neuman

185

145. Kappelmayer J, Nagy B Jr, Miszti-Blasius K, Hevessy Z, Setiadi H. The emerging value of P-selectin as a disease marker. Clin Chem Lab Med 2004;42:475– 86. 146. Fagerstam JP, Whiss PA, Strom M, Andersson RG. Expression of platelet P-selectin and detection of soluble P-selectin, NPY and RANTES in patients with inflammatory bowel disease. Inflamm Res 2000;49:466 –72. 147. Schurmann GM, Bishop AE, Facer P, Vecchio M, Lee JC, Rampton DS, et al. Increased expression of cell adhesion molecule P-selectin in active inflammatory bowel disease. Gut 1995;36:411– 8. 148. Strater J, Wedding U, Barth TF, Koretz K, Elsing C, Moller P. Rapid onset of apoptosis in vitro follows disruption of beta 1-integrin/matrix interactions in human colonic crypt cells. Gastroenterology 1996;110:1776 – 84. 149. Abramson O, Qiu S, Erle DJ. Preferential production of interferon-gamma by CD4⫹ T cells expressing the homing receptor integrin alpha4/beta7. Immunol 2001;103:155– 63. 150. Hu MC, Crowe DT, Weissman IL, Holzmann B. Cloning and expression of mouse integrin beta p(beta 7): a functional role in Peyer’s patch-specific lymphocyte homing. Proc Natl Acad Sci USA 1992;89:8254 – 8. 151. Butcher EC, Williams M, Youngman K, Rott L, Briskin M. Lymphocyte trafficking and regional immunity. Adv Immunol 1999;72:209 –53. 152. Sasaki M, Ostanin D, Elrod JW, Oshima T, Jordan P, Itoh M, et al. TNF-alpha -induced endothelial cell adhesion molecule expression is cytochrome P-450 monooxygenase dependent. Am J Physiol Cell Physiol 2003;284:C422– 8. 153. Van der Sluis M, De Koning BA, De Bruijn AC, Velcich A, Meijerink JP, Van Goudoever JB, et al. Muc2-deficient mice spontaneously develop colitis, indicating that MUC2 is critical for colonic protection. Gastroenterol 2006;131:117–29. 154. Fong S, Jones S, Renz ME, Chiu HH, Ryan AM, Presta LG, et al. Mucosal addressin cell adhesion molecule-1 (MAdCAM1). Its binding motif for alpha 4 beta 7 and role in experimental colitis. Immunol Res 1997;16:299 –311. 155. Vainer B, Nielsen OH. The influence of adhesion molecules in inflammatory bowel diseases. Ugeskr Laeger 1997;159: 3767–71. 156. Hamann A, Andrew DP, Jablonski-Westrich D, Hamann A, Holzmann B, Butcher EC. Role of alpha 4-integrins in lymphocyte homing to mucosal tissues in vivo. J Immunol 1994;152: 3282–93. 157. Picarella D, Hurlbut P, Rottman J, Shi X, Butcher E, Ringler DJ. Monoclonal antibodies specific for beta 7 integrin and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) reduce inflammation in the colon of scid mice reconstituted with CD45RB high CD4⫹ T cells. J Immunol 1997;158:2099 –106. 158. Arihiro S, Ohtani H, Suzuki M, Murata M, Ejima C, Oki M, et al. Differential expression of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) in ulcerative colitis and Crohn’s disease. Pathol Int 2002;52:367–74. 159. Haier J, Nicolson GL. Cell biology and clinical implications of adhesion molecules in colorectal diseases: colorectal cancers, infections and inflammatory bowel diseases. Clin Exp Metastasis 2000;18:623–38. 160. Hashimoto M, Shingu M, Ezaki I, Nobunaga M, Minamihara M, Kato K, et al. Production of soluble ICAM-1 from human endothelial cells induced by IL-1 beta and TNF-alpha. Inflammation 1994;18:163–73. 161. Shimizu Y, Newman W, Gopal TV, Horgan KJ, Graber N, Beall LD, et al. Four molecular pathways of T cell adhesion to endothelial cells: roles of LFA-1, VCAM-1, and ELAM-1 and

186

162.

163.

164.

165.

166.

167.

168.

169.

170.

171.

172.

173.

174.

175.

176.

Neuman

changes in pathway hierarchy under different activation conditions. J Cell Biol 1991;113:1203–12. Taniguchi T, Tsukada H, Nakamura H, Kodama M, Fukuda K, Saito T, et al. Effects of the anti-ICAM-1 monoclonal antibody on dextran sodium sulphate-induced colitis in rats. J Gastroenterol Hepatol 1998;13:945–949. Conner EM, Brand S, Davis JM, Laroux FS, Palombella VJ, Fuseler JW, et al. Proteasome inhibition attenuates nitric oxide synthase expression, VCAM-1 transcription and the development of chronic colitis. J Pharmacol Exp Ther 1997;282:1615–22. Burns RC, Rivera-Nieves J, Moskaluk CA, Matsumoto S, Cominelli F, Ley K. Antibody blockade of ICAM-1 and VCAM-1 ameliorates inflammation in the SAMP-1/Yit adoptive transfer model of Crohn’s disease in mice. Gastroenterol 2001;121:1428 – 36. Danese S, de la Motte C, Sturm A, Vogel JD, West GA, Strong SA, et al. Platelets trigger a CD40-dependent inflammatory response in the microvasculature of inflammatory bowel disease patients. Gastroenterol 2003;124:1249 – 64. Goke M, Hoffmann JC, Evers J, Kruger H, Manns MP. Elevated serum concentrations of soluble selectin and immunoglobulin type adhesion molecules in patients with inflammatory bowel disease. J Gastroenterol 1997;32:480 – 6. Nielsen OH, Langholz E, Hendel J, Brynskov J. Circulating soluble intercellular adhesion molecule-1 (sICAM-1) in active inflammatory bowel disease. Dig Dis Sci 1994;39:1918 –23. Sands BE, Winston BD, Salzberg B, Safdi M, Barish C, Wruble L, et al. Randomized, controlled trial of recombinant human interleukin-11 in patients with active Crohn’s disease. Aliment Pharmacol Ther 2002;16:399 – 406. Van Assche G, Dalle I, Noman M, Aerden I, Swijsen C, Asnong K, et al. A pilot study on the use of the humanized antiinterleukin-2 receptor antibody daclizumab in active ulcerative colitis. Am J Gastroenterol 2003;98:369 –76. Ito H, Takazoe M, Fukuda Y, Hibi T, Kusugami K, Andoh A, et al. A pilot randomized trial of a human anti-interleukin-6 receptor monoclonal antibody in active Crohn’s disease. Gastroenterol 2004;126:989 –96. Hanauer SB, Wagner CL, Bala M, Mayer L, Travers S, Diamond RH, et al. Incidence and importance of antibody responses to infliximab after maintenance or episodic treatment in Crohn’s disease. Clin Gastroenterol Hepatol 2004;2:542–53. Rutgeerts P, Feagan BG, Lichtenstein GR, Mayer LF, Schreiber S, Colombel JF, et al. Comparison of scheduled and episodic treatment strategies of infliximab in Crohn’s disease. Gastroenterol 2004;126:402–13. Sands BE, Anderson FH, Bernstein CN, Chey WY, Feagan BG, Fedorak RN, et al. Infliximab maintenance therapy for fistulizing Crohn’s disease. N Engl J Med 2004;350:876 – 85. Present DH, Rutgeerts P, Targan S, Hanauer SB, Mayer L, van Hogezand RA, et al. Infliximab for the treatment of fistulas in patients with Crohn’s disease. N Engl J Med 1999;340:1398 – 405. Su C, Salzberg BA, Lewis JD, Deren JJ, Kornbluth A, Katzka DA, et al. Efficacy of anti-tumor necrosis factor therapy in patients with ulcerative colitis. Am J Gastroenterol 2002;97: 2577– 84. Lugering A, Schmidt M, Lugering N, Pauels HG, Domschke W, Kucharzik T, et al. Infliximab induces apoptosis in monocytes from patients with chronic active Crohn’s disease by using a caspase-dependent pathway. Gastroenterol 2001;121:1145–57.

Translational Research April 2007

177. Martinez-Borra J, Lopez-Larrea C, Gonzalez S, Fuentes D, Dieguez A, Deschamps EM, et al. High serum tumor necrosis factor-alpha levels are associated with lack of response to infliximab in fistulizing Crohn’s disease. Am J Gastroenterol 2002;97:2350 – 6. 178. Stack WA, Mann SD, Roy AJ, Heath P, Sopwith M, Freeman J, et al. Randomised controlled trial of CDP571 antibody to tumour necrosis factor-alpha in Crohn’s disease. Lancet 1997; 349:521– 4. 179. Sandborn WJ, Feagan BG, Hanauer SB, Present DH, Sutherland LR, Kamm MA, et al. CDP571 Crohn’s Disease Study Group. An engineered human antibody to TNF (CDP571) for active Crohn’s disease: a randomized double-blind placebocontrolled trial. Gastroenterol 2001;120:1330 – 8. 180. Evans RC, Clarke L, Heath P, Stephens S, Morris AI, Rhodes JM. Treatment of ulcerative colitis with an engineered human anti-TNF alpha antibody CDP571. Aliment Pharmacol Ther 1997;11:1031–5. 181. Rutgeerts P, Lemmens L, Van Assche G, Noman M, BorghiniFuhrer I, Goedkoop R. Treatment of active Crohn’s disease with onercept (recombinant human soluble p55 tumour necrosis factor receptor): results of a randomized, open-label, pilot study. Aliment Pharmacol Ther 2003;17:185–92. 182. Rutgeerts P, Van Assche G, Vermeire S. Optimizing anti-TNF treatment in inflammatory bowel disease. Gastroenterol 2004; 126:1593– 610. 183. Sandborn W, Colombel JF, Enns R, Feagan B, Hanauer S, Lawrance I, et al. A phase III, double-blind, placebo-controlled study of the efficacy, safety, and tolerability of antegren (Natalizumab) in maintaining clinical response and remission in Crohn’s disease (ENACT-2). Gastroenterol 2004;127:332. 184. Ghosh S, Goldin E, Gordon FH, Malchow HA, Rask-Madsen J, Rutgeerts P, et al. Natalizumab for active Crohn’s disease. N Engl J Med 2003;348:24 –32. 185. Gordon FH, Hamilton MI, Donoghue S, Greenlees C, Palmer T, Rowley-Jones D, et al. A pilot study of treatment of active ulcerative colitis with natalizumab, a humanized monoclonal antibody to alpha-4 integrin. Aliment Pharmacol Ther 2002;16: 699 –705. 186. Rosenblum IY, Johnson RC, Schmahai TJ. Preclinical safety evaluation of recombinant human interleukin-10. Regul Toxicol Pharmacol 2002;35:56 –71. 187. Schreiber S, Fedorak RN, Nielsen OH, Wild G, Williams CN, Nikolaus S, et al. Safety and efficacy of recombinant human interleukin 10 in chronic active Crohn’s disease. Crohn’s Disease IL-10 Cooperative Study Group. Gastroenterol 2000;119: 1461–72. 188. Colombel JF, Rutgeerts P, Malchow H, Jacyna M, Nielsen OH, Rask-Madsen J, et al. Interleukin 10 (Tenovil) in the prevention of postoperative recurrence of Crohn’s disease. Gut 2001;49:42– 6. 189. Li MC, He SH. IL-10 and its related cytokines for treatment of inflammatory bowel disease. World J Gastroenterol 2004;10: 620 –5. 190. Rogler G. Significance of anti-inflammatory effects of PPARgamma agonists? Gut 2006;55:110413. 191. Adachi M, Kurotani R, Morimura K, Shah Y, Sanford M, Madison BB, et al. Peroxisome proliferator activated receptor gamma in colonic epithelial cells protects against experimental inflammatory bowel disease. Gut 2006;55:1067–9.