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Interleukin 1β is expressed predominantly by enterocytes in experimental colitis
GASTROENTEROLOGY
1991;100:1180-1186
Interleukin 18 Is Expressed Predominantly by Enterocytes in Experimental Colitis SANDRA A. RADEMA, SANDER J. H. VAN DEVENTER, and ANTHONY CERAMI Laboratory of Medical Biochemistry, Rockefeller University, New York, New York
The cytokine interleukin lf3is an important mediator of inflammatory processes capable of inducing eicosanoid production, T-cell activation, and increased vascular permeability. In this study, in situ hybridization techniques were used to delineate the kinetics and cellular source of induced interleukin lf3in acute experimental colitis. The induction of interleukin lf3messenger RNA was an early phenomenon and occurred predominantly in undifferentiated cells located in the basal part of the mucosal crypts but not in differentiated enterocytes. The undifferentiated enterocytes retained the messenger RNA during differentiation and migration to more apical parts of the crypts. These results suggest that induction of interleukin 18 messenger RNA in enterocytes is causally related to the subsequent inflammatory changes seen in acute experimental colitis. he major hallmark of ulcerative colitis is inflammation of the mucosa of the large bowel, histologically characterized by edema, infiltration of neutrophils and macrophages, the formation of crypt abscesses, and eventually extensive tissue damage (1). The cause of mucosal inflammation in ulcerative colitis is unknown. Experimental and clinical studies have documented an increase in the mucosal content of the prostaglandins E, and F1,, as well as thromboxane B, (zJ), but their pathogenic roles remains uncertain and treatment with prostaglandin synthetase inhibitors is not beneficial in ulcerative colitis (4). Although there is more convincing evidence for the pathogenic importance of leukotriene B, (LTB,) (5), it is unlikely that the complete spectrum of inflammatory changes can be explained solely by increased synthesis of this eicosanoid. Interleukin l@ (IL-l@) is a 17-kilodalton protein originally discovered as a product of activated phagocytic cells (6). Subsequently it has been discovered
T
that many stimuli can induce the synthesis of IL-lp in a wide range of cells. Interleukin 1 p mediates recruitment of inflammatory cells by induction of endothelial leukocyte adhesion molecules in postcapillary venules (7-9). In addition, IL-lp functions as an important costimulatory signal in T-cell activation (10). Recently, an increase in the mucosal concentration of IL-lp has been reported in experimental colitis (11). Moreover, experimental infusion of IL-l in the normal colon causes increased mucosal production of prostaglandin E,, F1,, and thromboxane B, (z), suggesting that IL-lp may mediate the increased eicosanoid production that is observed in colitis. In the present study, we investigated the early kinetics and the cellular source of induced IL-lp in experimental colitis in rats using in situ hybridization techniques to delineate the importance of IL-lp for the pathogenesis of mucosal inflammation in more detail. Materials
and Methods
Animals Female Sprague-Dawley rats 2 1 weeks of age, weighing about 300 g, were housed at a maximum of 3 rats per cage and provided with standard pelleted rodent food (Purina Lab Chow; Fredrick Feeds, Congars, NY) and tap water ad libitum. Colitis was induced by rectally instilling 2 mL of 10% acetic acid using a plastic canula positioned 2 cm proximal to the anus (12). Control rats received 2 mL of 0.9% saline rectally. The rats were anesthetized with pentobarbital 2,4, 8, 12, and 24 hours following the enema, and a
Abbreviations used in this paper: IL, interleukin; LTB,, leukotriene B,. o 1991 by the American Gastroenterological Association 0016~5085/91/$3.00
May 1991
INTERLEUKIN
lf3 IN EXPERIMENTAL
COLITIS
Figure 1. H&E-stained tions of rat colon.
1181
sec-
A. Twenty-four hours after treatment with 2 mL 0.9% saline (low-power magnification). B. Extensive inflammatory reaction, ulceration, and necrosis 24 hours after treatment with 10% acetic acid (lowpower magnification). C. Inflammatory reaction at 24 hours after acetic acid treatment [high-power magnification).
1182
GASTROENTEROLOGY
RADEMA ET AL.
Vol. 100, No. 5
Figure 2. Lack of IL-+specific in situ hybridization in cross section through saline-treated control colon (low-power magnification).
colon segment located 6 cm from the anus was removed. Aliquots were snap-frozen in liquid nitrogen for in situ hybridization or preserved in formalin for histological examination. This time course was repeated three times with 1 rat at each time point. The rats were subsequently killed by CO, asphyxiation. This protocol was approved by the Animal Care and Use Committee of The Rockefeller University.
Probe An IL-1P-specific complementary DNA (cDNA) contained within plasmid pBR322 (kindly provided by Patrick Gray, Genentech Inc., South San Francisco, CA) was digested with the restriction enzyme EcoRI and the 1358 bp IL-l@ coding fragment was isolated using Geneclean II (Bio 101 Inc., La Jolla, CA). The probe was labeled by randomly primed incorporation of digoxigenin-conjugated deoxyuridine triphosphate (Boehringer Manheim, Indianapolis, IN).
In Situ Hybridization Frozen sections, 8-km thick, were cut on a Damon minotome cryostat (I.E.C.-division, Needham, MA) and mounted on gelatin/chrome alum-coated slides. The tissue was fixed in 4% paraformaldehyde in phosphate-buffered saline (PBS), incubated in 2x standard saline citrate, and rinsed several times in PBS. Prehybridization was performed for 30 minutes at room temperature (Boehringer Manheim). Mounted sections were then covered with 2 ng of labeled probe in 20 ILL hybridization solution and incubated overnight at 42°C. After several washing steps, specific hybridization was visualized, using alkaline phosphatase-labeled antidigoxigenin antibodies and a subsequent enzyme-catalyzed color reaction with 5-bromo+
chloro-3-indolylphosphate (Boehringer Mannheim].
and nitroblue
tetrazolium
salt
Results Macroscopical
Pathology
Diarrhea was present in all animals treated with acetic acid. In addition, all treated animals showed signs of systemic illness, such as lethargy and ruffled fur. Acetic acid-treated colons showed marked dilatation, scattered intramural hemorrhages, and focal necrosis. Blood vessels on the serosal surface of the colon appeared dilated. Intraperitoneal adhesions were sometimes noted 12 or more hours after induction of colitis. Colons of saline-infused controls appeared normal.
Microscopic Histopathology and In Situ Hybridization An inflammatory response, characterized by a predominantly polymorphonuclear cell influx, edema, and vasodilatation, was present in all colons treated with acetic acid for 8 to 24 hours previously, whereas no changes were observed bowel samples. In addition,
in sections from 12 or more hours
control follow-
ing induction of colitis, focal ulcerations were observed (Figure 1). Interleukin lp messenger RNA (mRNA) was detected by in situ hybridization in acetic acid-treated colons after 4 or more hours, before significant leukocyte infiltration and edema were apparent. In salinetreated control colons and in colons removed 2 hours
May 1991
after acetic acid instillation, no positive staining for IL-ll3 was detected (Figure 2). Positive hybridization first became apparent at 4 hours and was located in undifferentiated enterocytes in the crypt bases. Eight hours after the induction of colitis, intense hybridization was located in basal portions of the mucosal
INTERLEUKIN
lfi IN EXPERIMENTAL
COLITIS
1183
crypts (Figure 3). At 12 and 24 hours, slightly weaker and more diffuse staining was observed in epithelial cells, including goblet cells, located more apically in crypts; and, at these later time points, IL-l(3 mRNA levels had decreased substantially in the basal cryptal cells (Figure 4). Scattered cells (presumably macro-
Figure 3. Ext :ensive staining of IL..l@-specific mR?qA in mucr )sal crypt bases 8 hours after acetic aci Id instillatic m at low-f lower (4 and high-pow rer (B) 1nagnificatio n.
1184
GASTROENTEROLOGY
RADEMA ET AL.
Vol. 100, No. 5
Figure 4. Cross section at 24 hours after induction of colitis at low-power (A) and high-power (B) magnification. Less abundant IL-lp mRNA staining, predominantly in mucosal cells (including goblet cells] located in the apices of the crypts. The CUTOWpoints to the luminal side of the mucosa.
phages) in the inflammatory infiltrate IL-l(3 mRNA at later time points.
also expressed
Discussion Our results indicate that IL-ll3 mRNA is rapidly induced during mucosal inflammation resulting
from experimental infusion of dilute acetic acid. In situ hybridization showed that IL-ll3 mRNA initially appeared in undifferentiated enterocytes located in basal portions of the mucosal crypts. With increasing time, cells located more apically were positively stained, presumably reflecting the natural maturation and migration of mucosal cells from their birthplace
May 1991
in crypts toward the bowel lumen. Therefore, enterocytes seem to retain, or possibly continue to express induced IL-1B mRNA during differentiation. However, in already differentiated cells, IL-l(3 was not induced. In this experimental model of acute colitis, a predominantly polymorphonuclear cellular reaction was observed, and scattered inflammatory cells (presumably macrophages) present in the submucosa were shown to synthesize IL-l(3 mRNA. However, mucosal cells were the predominant IL-l@producing cells. The time course of induction of IL-l(3 in our study is identical to the kinetics of IL-lb mRNA appearance in another model of acute colitis induced by immune complexes in rabbits (13). In yet another model of colitis induced in rats by ethanol and trinitrobenzene sulfonic acid, IL-l(3 protein can be detected at 24 hours (ll), suggesting that the IL-1B found to be induced in this study may well be translated. In fact, enterocytes have been shown to produce an IL-l-like factor in vitro in the context of antigen presentation to T cells (14).The origin of experimental colitis clearly differs from ulcerative colitis. However, an increased mucosal production of IL-l B has recently been demonstrated during active ulcerative colitis (15). Interleukin l(3 has several biological effects that may underlie the inflammatory changes that are observed in colitis. First, IL-l(3 increases vascular permeability, causing edema (16). Second, IL-1B induces expression of endothelial-leukocyte and endotheliallymphocyte adhesion molecules on endothelial cells in postcapillary venules (7-9). These adhesion molecules cause neutrophils and lymphocytes to adhere to endothelial cells in the microvasculature which is the first step in recruitment of these cells to sites of local inflammation. Moreover, local injection of IL-1B induces a rapid influx of neutrophils by a prostaglandinindependent mechanism (17).Third, IL-l(3 is capable of inducing thromboxane B,, PGE,, and PGF,, in normal colonic tissue (z), and the mucosal concentrations of these eicosanoids are increased in experimental and ulcerative colitis (18). Finally, IL-l(3 is an important costimulatory signal in T-cell activation. Diseased or stressed mucosal cells in the small and large intestine are known to express HLA class II molecules (19), indicating that these cells are capable of antigen presentation and suggesting that they may therefore activate T cells. Importantly, basally located cryptal cells are the predominant HLA class IIexpressing cells (20). Our results indicate that these cells are also capable of synthesizing the costimulatory signal, IL-1B. Thus, enterocytes seem to be fully equipped to function as accessory cells in major histocompatibility complex class II restricted T-cell activation.
INTERLELJKJN l@ IN EXPERIMENTAL
COLITIS
1165
In conclusion, this study showed that synthesis of IL-l(3 mRNA by mucosal cells was an early feature of acute experimental colitis and preceded frank tissue damage. Therefore, it seems that induction of this cytokine could be causally related to the subsequent inflammatory reaction.
References 1. Kirsner
JB, Shorter
Philadelphia:
RG, eds. Inflammatory
bowel
diseases.
Lea & Febiger, 1988.
2. Cominelli F, Nast CC, Dinarello CA, Gentilini P, Zipser RD. Regulation of eicosanoid production in rabbit colon by Interleukin-l. Gastroenterology 1989;97:1400-1405. 3. Lauritsen K, Laursen LS, Bukhave K, Rask-Madsen J. In vivo profiles of eicosanoids in ulcerative colitis, Crohn’s colitis, and Clostridium difficile colitis. Gastroenterology 1988;95:11-17. 4. Peppercorn MA. Advances in drug therapy for inflammatory bowel disease. Ann Intern Med 1990;112:50-60. 5. Vilaseca J, Salas A, Guarner F, Rodriques R, Malagelada J. Participation of thromboxane and other eicosanoid synthesis in the course of experimental colitis. Gastroenterology 1990;9a: 2699277. 6. Oppenheim JJ, Kovacs EJ, Matushima K, Durum SK. There is more than one Interleukin-1. Immunol Today 1966;7:45-55. 7. Bevilacqua MP, Stengelin S, Gimbrone MA Jr, Seed B. Endothelial leukocyte adhesion molecule 1: An inducible receptor for neutrophils related to complement regulatory proteins and lectins.Science 1989;243:1160-1165. a. Dustin ML, Springer TA. Lymphocyte function-associated antigen-l (LFA-1) interaction with intercellular adhesion molecule-l (ICAM-1) is one of at least three mechanisms of lymphocyte adhesion to cultures endothelial cells. J Cell Bio11988;107: 321-331. 9. Osborn L, Hession C, Tizard R, Vassal0 C, Luhowskyi S, Chi-Rosso G, Lobb R. Direct expression cloning of vascular cell adhesion molecule 1, a cytokine-induced endothelial protein that binds to lymphocytes. Cell 1989;59:1203-1211. 10. Roitt I. Essential immunology. Oxford: Blackwell Scientific, 1988. 11. Rachmilewitz D, Simon PL, Schwartz LW, Griswold DE, Fondacaro JD, Wasserman MA. Inflammatory mediators of experimental colitis in rats. Gastroenterology 1969;97:326337. 12. Zetlin IJ, Noris AA. Animal models of colitis. In: Chadwick VS, ed. Mechanisms of gastrointestinal inflammation. Proceedings of the fourth BSG-SK&F international workshop. England: StandsteadAbbots, 1983:70-73. 13. Cominelli F, Nast CC, Schindler R, Clark B, Llerena R, Eysselein VE, Dinarello CA. Interleukin-1 gene expression and
14.
15.
16.
17.
production is an early event in rabbit formalin-immune complex colitis (abstr). Gastroenterology 1990;96:A442. Bland PW. Antigen presentation by gut epithelial cells: secretion by rat enterocytes of a factor with IL-l like activity. Adv ExpMedBiol1987;216A:219-225. Ligumsky M, Simon PL, Karmeli F, Rachmilewitz D. Role of IL-1 in inflammatory bowel disease. Enhanced production during active disease. Gut 1990;31:666-669. Martin S, Maruta K, Burkart V, Gillis S, Kolb H. IL-1 and IFN-gamma increase vascular permeability. Immunology 1988; 64:301-305. Sayers TJ, Wiltrout TA, Bull CA, Denn AC III, Pilaro A, Lohesh
1186
GASTROENTEROLOGY
RADEMA ET AL.
B. Effects of cytokines on polymorphonuclear neutrophil infiltration in the mouse. Prostaglandin- and leukotriene-independent induction of infiltration by IL-1 and tumor necrosis factor. J Immunol1988;141:167O-1677. 18. Donowitz M. Arachidonic acid metabolites and their role in inflammatory bowel disease. Gastroenterology 1985;88:580587. 19.
Mayer L, Shlien R. Evidence for function of Ia molecules epithelial cells in man. JExp Med 1987;166:1471-1483.
20.
Bland P. MHC class II expression Immunol Today 1988;9:174-178.
on gut
by the gut epithelium.
Vol. 100, No? 5
Received May 30,199O. Accepted October 1,199O. Address requests for reprints to: Sander van Deventer, M.D., Department of Gastroenterology, Academic Medical Center, / Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Sandra A. Radema is supported by a grant of The Netherlands Digestive Diseases Foundation, Breukelen, The Netherlands. Sander J. H. van Deventer is a fellow of the Royal Dutch Academy of Sciences. The authors thank Barbara O’Loughlin, Frank van den Berg, Sue Morgello, and Ed Skolnik for helpful advice during this study, and Kirk Manogue for critically reviewing the manuscript.
1991;100:1180-1186
Interleukin 18 Is Expressed Predominantly by Enterocytes in Experimental Colitis SANDRA A. RADEMA, SANDER J. H. VAN DEVENTER, and ANTHONY CERAMI Laboratory of Medical Biochemistry, Rockefeller University, New York, New York
The cytokine interleukin lf3is an important mediator of inflammatory processes capable of inducing eicosanoid production, T-cell activation, and increased vascular permeability. In this study, in situ hybridization techniques were used to delineate the kinetics and cellular source of induced interleukin lf3in acute experimental colitis. The induction of interleukin lf3messenger RNA was an early phenomenon and occurred predominantly in undifferentiated cells located in the basal part of the mucosal crypts but not in differentiated enterocytes. The undifferentiated enterocytes retained the messenger RNA during differentiation and migration to more apical parts of the crypts. These results suggest that induction of interleukin 18 messenger RNA in enterocytes is causally related to the subsequent inflammatory changes seen in acute experimental colitis. he major hallmark of ulcerative colitis is inflammation of the mucosa of the large bowel, histologically characterized by edema, infiltration of neutrophils and macrophages, the formation of crypt abscesses, and eventually extensive tissue damage (1). The cause of mucosal inflammation in ulcerative colitis is unknown. Experimental and clinical studies have documented an increase in the mucosal content of the prostaglandins E, and F1,, as well as thromboxane B, (zJ), but their pathogenic roles remains uncertain and treatment with prostaglandin synthetase inhibitors is not beneficial in ulcerative colitis (4). Although there is more convincing evidence for the pathogenic importance of leukotriene B, (LTB,) (5), it is unlikely that the complete spectrum of inflammatory changes can be explained solely by increased synthesis of this eicosanoid. Interleukin l@ (IL-l@) is a 17-kilodalton protein originally discovered as a product of activated phagocytic cells (6). Subsequently it has been discovered
T
that many stimuli can induce the synthesis of IL-lp in a wide range of cells. Interleukin 1 p mediates recruitment of inflammatory cells by induction of endothelial leukocyte adhesion molecules in postcapillary venules (7-9). In addition, IL-lp functions as an important costimulatory signal in T-cell activation (10). Recently, an increase in the mucosal concentration of IL-lp has been reported in experimental colitis (11). Moreover, experimental infusion of IL-l in the normal colon causes increased mucosal production of prostaglandin E,, F1,, and thromboxane B, (z), suggesting that IL-lp may mediate the increased eicosanoid production that is observed in colitis. In the present study, we investigated the early kinetics and the cellular source of induced IL-lp in experimental colitis in rats using in situ hybridization techniques to delineate the importance of IL-lp for the pathogenesis of mucosal inflammation in more detail. Materials
and Methods
Animals Female Sprague-Dawley rats 2 1 weeks of age, weighing about 300 g, were housed at a maximum of 3 rats per cage and provided with standard pelleted rodent food (Purina Lab Chow; Fredrick Feeds, Congars, NY) and tap water ad libitum. Colitis was induced by rectally instilling 2 mL of 10% acetic acid using a plastic canula positioned 2 cm proximal to the anus (12). Control rats received 2 mL of 0.9% saline rectally. The rats were anesthetized with pentobarbital 2,4, 8, 12, and 24 hours following the enema, and a
Abbreviations used in this paper: IL, interleukin; LTB,, leukotriene B,. o 1991 by the American Gastroenterological Association 0016~5085/91/$3.00
May 1991
INTERLEUKIN
lf3 IN EXPERIMENTAL
COLITIS
Figure 1. H&E-stained tions of rat colon.
1181
sec-
A. Twenty-four hours after treatment with 2 mL 0.9% saline (low-power magnification). B. Extensive inflammatory reaction, ulceration, and necrosis 24 hours after treatment with 10% acetic acid (lowpower magnification). C. Inflammatory reaction at 24 hours after acetic acid treatment [high-power magnification).
1182
GASTROENTEROLOGY
RADEMA ET AL.
Vol. 100, No. 5
Figure 2. Lack of IL-+specific in situ hybridization in cross section through saline-treated control colon (low-power magnification).
colon segment located 6 cm from the anus was removed. Aliquots were snap-frozen in liquid nitrogen for in situ hybridization or preserved in formalin for histological examination. This time course was repeated three times with 1 rat at each time point. The rats were subsequently killed by CO, asphyxiation. This protocol was approved by the Animal Care and Use Committee of The Rockefeller University.
Probe An IL-1P-specific complementary DNA (cDNA) contained within plasmid pBR322 (kindly provided by Patrick Gray, Genentech Inc., South San Francisco, CA) was digested with the restriction enzyme EcoRI and the 1358 bp IL-l@ coding fragment was isolated using Geneclean II (Bio 101 Inc., La Jolla, CA). The probe was labeled by randomly primed incorporation of digoxigenin-conjugated deoxyuridine triphosphate (Boehringer Manheim, Indianapolis, IN).
In Situ Hybridization Frozen sections, 8-km thick, were cut on a Damon minotome cryostat (I.E.C.-division, Needham, MA) and mounted on gelatin/chrome alum-coated slides. The tissue was fixed in 4% paraformaldehyde in phosphate-buffered saline (PBS), incubated in 2x standard saline citrate, and rinsed several times in PBS. Prehybridization was performed for 30 minutes at room temperature (Boehringer Manheim). Mounted sections were then covered with 2 ng of labeled probe in 20 ILL hybridization solution and incubated overnight at 42°C. After several washing steps, specific hybridization was visualized, using alkaline phosphatase-labeled antidigoxigenin antibodies and a subsequent enzyme-catalyzed color reaction with 5-bromo+
chloro-3-indolylphosphate (Boehringer Mannheim].
and nitroblue
tetrazolium
salt
Results Macroscopical
Pathology
Diarrhea was present in all animals treated with acetic acid. In addition, all treated animals showed signs of systemic illness, such as lethargy and ruffled fur. Acetic acid-treated colons showed marked dilatation, scattered intramural hemorrhages, and focal necrosis. Blood vessels on the serosal surface of the colon appeared dilated. Intraperitoneal adhesions were sometimes noted 12 or more hours after induction of colitis. Colons of saline-infused controls appeared normal.
Microscopic Histopathology and In Situ Hybridization An inflammatory response, characterized by a predominantly polymorphonuclear cell influx, edema, and vasodilatation, was present in all colons treated with acetic acid for 8 to 24 hours previously, whereas no changes were observed bowel samples. In addition,
in sections from 12 or more hours
control follow-
ing induction of colitis, focal ulcerations were observed (Figure 1). Interleukin lp messenger RNA (mRNA) was detected by in situ hybridization in acetic acid-treated colons after 4 or more hours, before significant leukocyte infiltration and edema were apparent. In salinetreated control colons and in colons removed 2 hours
May 1991
after acetic acid instillation, no positive staining for IL-ll3 was detected (Figure 2). Positive hybridization first became apparent at 4 hours and was located in undifferentiated enterocytes in the crypt bases. Eight hours after the induction of colitis, intense hybridization was located in basal portions of the mucosal
INTERLEUKIN
lfi IN EXPERIMENTAL
COLITIS
1183
crypts (Figure 3). At 12 and 24 hours, slightly weaker and more diffuse staining was observed in epithelial cells, including goblet cells, located more apically in crypts; and, at these later time points, IL-l(3 mRNA levels had decreased substantially in the basal cryptal cells (Figure 4). Scattered cells (presumably macro-
Figure 3. Ext :ensive staining of IL..l@-specific mR?qA in mucr )sal crypt bases 8 hours after acetic aci Id instillatic m at low-f lower (4 and high-pow rer (B) 1nagnificatio n.
1184
GASTROENTEROLOGY
RADEMA ET AL.
Vol. 100, No. 5
Figure 4. Cross section at 24 hours after induction of colitis at low-power (A) and high-power (B) magnification. Less abundant IL-lp mRNA staining, predominantly in mucosal cells (including goblet cells] located in the apices of the crypts. The CUTOWpoints to the luminal side of the mucosa.
phages) in the inflammatory infiltrate IL-l(3 mRNA at later time points.
also expressed
Discussion Our results indicate that IL-ll3 mRNA is rapidly induced during mucosal inflammation resulting
from experimental infusion of dilute acetic acid. In situ hybridization showed that IL-ll3 mRNA initially appeared in undifferentiated enterocytes located in basal portions of the mucosal crypts. With increasing time, cells located more apically were positively stained, presumably reflecting the natural maturation and migration of mucosal cells from their birthplace
May 1991
in crypts toward the bowel lumen. Therefore, enterocytes seem to retain, or possibly continue to express induced IL-1B mRNA during differentiation. However, in already differentiated cells, IL-l(3 was not induced. In this experimental model of acute colitis, a predominantly polymorphonuclear cellular reaction was observed, and scattered inflammatory cells (presumably macrophages) present in the submucosa were shown to synthesize IL-l(3 mRNA. However, mucosal cells were the predominant IL-l@producing cells. The time course of induction of IL-l(3 in our study is identical to the kinetics of IL-lb mRNA appearance in another model of acute colitis induced by immune complexes in rabbits (13). In yet another model of colitis induced in rats by ethanol and trinitrobenzene sulfonic acid, IL-l(3 protein can be detected at 24 hours (ll), suggesting that the IL-1B found to be induced in this study may well be translated. In fact, enterocytes have been shown to produce an IL-l-like factor in vitro in the context of antigen presentation to T cells (14).The origin of experimental colitis clearly differs from ulcerative colitis. However, an increased mucosal production of IL-l B has recently been demonstrated during active ulcerative colitis (15). Interleukin l(3 has several biological effects that may underlie the inflammatory changes that are observed in colitis. First, IL-l(3 increases vascular permeability, causing edema (16). Second, IL-1B induces expression of endothelial-leukocyte and endotheliallymphocyte adhesion molecules on endothelial cells in postcapillary venules (7-9). These adhesion molecules cause neutrophils and lymphocytes to adhere to endothelial cells in the microvasculature which is the first step in recruitment of these cells to sites of local inflammation. Moreover, local injection of IL-1B induces a rapid influx of neutrophils by a prostaglandinindependent mechanism (17).Third, IL-l(3 is capable of inducing thromboxane B,, PGE,, and PGF,, in normal colonic tissue (z), and the mucosal concentrations of these eicosanoids are increased in experimental and ulcerative colitis (18). Finally, IL-l(3 is an important costimulatory signal in T-cell activation. Diseased or stressed mucosal cells in the small and large intestine are known to express HLA class II molecules (19), indicating that these cells are capable of antigen presentation and suggesting that they may therefore activate T cells. Importantly, basally located cryptal cells are the predominant HLA class IIexpressing cells (20). Our results indicate that these cells are also capable of synthesizing the costimulatory signal, IL-1B. Thus, enterocytes seem to be fully equipped to function as accessory cells in major histocompatibility complex class II restricted T-cell activation.
INTERLELJKJN l@ IN EXPERIMENTAL
COLITIS
1165
In conclusion, this study showed that synthesis of IL-l(3 mRNA by mucosal cells was an early feature of acute experimental colitis and preceded frank tissue damage. Therefore, it seems that induction of this cytokine could be causally related to the subsequent inflammatory reaction.
References 1. Kirsner
JB, Shorter
Philadelphia:
RG, eds. Inflammatory
bowel
diseases.
Lea & Febiger, 1988.
2. Cominelli F, Nast CC, Dinarello CA, Gentilini P, Zipser RD. Regulation of eicosanoid production in rabbit colon by Interleukin-l. Gastroenterology 1989;97:1400-1405. 3. Lauritsen K, Laursen LS, Bukhave K, Rask-Madsen J. In vivo profiles of eicosanoids in ulcerative colitis, Crohn’s colitis, and Clostridium difficile colitis. Gastroenterology 1988;95:11-17. 4. Peppercorn MA. Advances in drug therapy for inflammatory bowel disease. Ann Intern Med 1990;112:50-60. 5. Vilaseca J, Salas A, Guarner F, Rodriques R, Malagelada J. Participation of thromboxane and other eicosanoid synthesis in the course of experimental colitis. Gastroenterology 1990;9a: 2699277. 6. Oppenheim JJ, Kovacs EJ, Matushima K, Durum SK. There is more than one Interleukin-1. Immunol Today 1966;7:45-55. 7. Bevilacqua MP, Stengelin S, Gimbrone MA Jr, Seed B. Endothelial leukocyte adhesion molecule 1: An inducible receptor for neutrophils related to complement regulatory proteins and lectins.Science 1989;243:1160-1165. a. Dustin ML, Springer TA. Lymphocyte function-associated antigen-l (LFA-1) interaction with intercellular adhesion molecule-l (ICAM-1) is one of at least three mechanisms of lymphocyte adhesion to cultures endothelial cells. J Cell Bio11988;107: 321-331. 9. Osborn L, Hession C, Tizard R, Vassal0 C, Luhowskyi S, Chi-Rosso G, Lobb R. Direct expression cloning of vascular cell adhesion molecule 1, a cytokine-induced endothelial protein that binds to lymphocytes. Cell 1989;59:1203-1211. 10. Roitt I. Essential immunology. Oxford: Blackwell Scientific, 1988. 11. Rachmilewitz D, Simon PL, Schwartz LW, Griswold DE, Fondacaro JD, Wasserman MA. Inflammatory mediators of experimental colitis in rats. Gastroenterology 1969;97:326337. 12. Zetlin IJ, Noris AA. Animal models of colitis. In: Chadwick VS, ed. Mechanisms of gastrointestinal inflammation. Proceedings of the fourth BSG-SK&F international workshop. England: StandsteadAbbots, 1983:70-73. 13. Cominelli F, Nast CC, Schindler R, Clark B, Llerena R, Eysselein VE, Dinarello CA. Interleukin-1 gene expression and
14.
15.
16.
17.
production is an early event in rabbit formalin-immune complex colitis (abstr). Gastroenterology 1990;96:A442. Bland PW. Antigen presentation by gut epithelial cells: secretion by rat enterocytes of a factor with IL-l like activity. Adv ExpMedBiol1987;216A:219-225. Ligumsky M, Simon PL, Karmeli F, Rachmilewitz D. Role of IL-1 in inflammatory bowel disease. Enhanced production during active disease. Gut 1990;31:666-669. Martin S, Maruta K, Burkart V, Gillis S, Kolb H. IL-1 and IFN-gamma increase vascular permeability. Immunology 1988; 64:301-305. Sayers TJ, Wiltrout TA, Bull CA, Denn AC III, Pilaro A, Lohesh
1186
GASTROENTEROLOGY
RADEMA ET AL.
B. Effects of cytokines on polymorphonuclear neutrophil infiltration in the mouse. Prostaglandin- and leukotriene-independent induction of infiltration by IL-1 and tumor necrosis factor. J Immunol1988;141:167O-1677. 18. Donowitz M. Arachidonic acid metabolites and their role in inflammatory bowel disease. Gastroenterology 1985;88:580587. 19.
Mayer L, Shlien R. Evidence for function of Ia molecules epithelial cells in man. JExp Med 1987;166:1471-1483.
20.
Bland P. MHC class II expression Immunol Today 1988;9:174-178.
on gut
by the gut epithelium.
Vol. 100, No? 5
Received May 30,199O. Accepted October 1,199O. Address requests for reprints to: Sander van Deventer, M.D., Department of Gastroenterology, Academic Medical Center, / Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Sandra A. Radema is supported by a grant of The Netherlands Digestive Diseases Foundation, Breukelen, The Netherlands. Sander J. H. van Deventer is a fellow of the Royal Dutch Academy of Sciences. The authors thank Barbara O’Loughlin, Frank van den Berg, Sue Morgello, and Ed Skolnik for helpful advice during this study, and Kirk Manogue for critically reviewing the manuscript.