- Email: [email protected]
Hair follicle stem cells in the pathogenesis of the scarring process in cutaneous lupus erythematosus
Autoimmunity Reviews 8 (2009) 474–477
Contents lists available at ScienceDirect
Autoimmunity Reviews j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / a u t r e v
Hair follicle stem cells in the pathogenesis of the scarring process in cutaneous lupus erythematosus Khitam Al-Refu a,⁎, Mark Goodfield a,b,1 a b
Department of Internal Medicine, School of Medicine, Mutah University, Karak, PO Box 51, post code 61710, Jordan Department of Dermatology, Leeds General Infirmary, Great George Street, Leeds, West Yorkshire, LS1 3EX, England, UK
a r t i c l e
i n f o
Available online 20 January 2009 Keywords: Cutaneous lupus erythematosus (CLE) Scar Stem cells of hair follicle
a b s t r a c t Lupus erythematosus (LE) is an autoimmune disease that can affect one or more internal organs (systemic LE [SLE]) as well as the skin (CLE). Common cutaneous subtypes of CLE are chronic CLE (CCLE) and subacute CLE (SCLE). CCLE is the only type of CLE which heals with scarring and this may affect any site in the body. The fact that inflammation in CCLE generally involves the bulge area of the follicles (where the stem cells reside) raises the possibility that damage to the stem cells may be one process leading to permanent loss of follicles. One of the most useful distinctive markers of the stem cells is cytokeratin 15 (CK15) and this has been used in some studies to demonstrate the involvement of the bulge region in the scarring process in primary cicatricial alopecia and DLE. The bulge region appears to be involved in the scarring process in CLE and other types of cicatricial alopecia as part of broader involvement of the hair follicles; it is secondarily affected by the surrounding inflammatory cell infiltrate. Expression of the stem cell marker CK15 diminished and was then absent indicating either damage to stem cells or differentiation to help in the repair process. © 2008 Elsevier B.V. All rights reserved.
Contents 1. 2.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The bulge region of the hair follicle, stem cell location and their specific markers 2.1. The bulge region of the hair follicle . . . . . . . . . . . . . . . . . . 2.2. The hair follicle stem cell location. . . . . . . . . . . . . . . . . . . 2.3. Hair follicle stem cell markers . . . . . . . . . . . . . . . . . . . . 3. The scarring response in CLE . . . . . . . . . . . . . . . . . . . . . . . . 4. Autoimmunity and scarring process in CLE . . . . . . . . . . . . . . . . . . 4.1. Pathogenesis of CLE . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Role of lymphocytes in scarring process in CLE . . . . . . . . . . . . . 5. The stem cells of the hair follicle and scarring process in CCLE . . . . . . . . 5.1. Hair follicle and scarring alopecia . . . . . . . . . . . . . . . . . . . 5.2. Involvement of bulge region in primary scarring alopecia . . . . . . . . 5.3. Involvement of the bulge region in CLE . . . . . . . . . . . . . . . . 6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Take-home messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
⁎ Corresponding author. Tel.: +962 795050339. E-mail addresses: [email protected] (K. Al-Refu), mark.goodfi[email protected] (M. Goodfield). 1 Tel.: +44 1132432799; fax: +44 1133926336. 1568-9972/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.autrev.2008.12.015
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. 475 . 475 . 475 . 475 . 475 . 475 . 475 . 475 . 475 . 475 . 475 . 476 . 476 . 476 . 476 . 477
K. Al-Refu, M. Goodfield / Autoimmunity Reviews 8 (2009) 474–477
475
1. Introduction
3. The scarring response in CLE
Lupus erythematosus (LE) is an autoimmune disease that can affect one or more internal organ (systemic LE [SLE]) as well as the skin (CLE). The common cutaneous subtypes are chronic CLE (CCLE) and subacute CLE (SCLE). The fact that inflammation in CCLE generally involves the bulge area of the follicles [1] raises the possibility that damage to the stem cells of the bulge region may be one process leading to permanent loss of follicles. This review considers the potential role of follicular stem cells in the pathogenesis of scarring process in CLE. 2. The bulge region of the hair follicle, stem cell location and their specific markers
The typical clinical manifestation of CCLE is discoid lupus erythematosus (DLE), and it is the only type of cutaneous lupus which heals with scarring [15]. This scarring process commonly involves the scalp and face, but may involve any site [16]. The main histopathologic aspects of DLE are appendageal destruction, follicular hyperkeratosis, lymphocytic infiltration, thickened basement membrane zone and basal vacuolar degeneration [17]. Loss of appendages can be considered as a characteristic feature of DLE; since it is not usually evident in acute or subacute forms of CLE [18]. The localization of the hair follicle stem cells to the bulge region of hair follicle may explain why the inflammatory process in CLE causes permanent alopecia.
2.1. The bulge region of the hair follicle
4. Autoimmunity and scarring process in CLE
The bulge region forms an area of the outer root sheath of both mouse and human hair follicles, located in the mid portion of the follicle, which is at the insertion of the arrector pili muscle (Fig. 1a,b). Although several lines of evidence have suggested that the bulge region also provides a niche for keratinocytes stem cells [2], anatomic boundaries are ill defined [3]. Recently, Tiede et al. [4] have identified a prominent ‘follicular trochanter’-like epithelial structure in the bulge region of the outer root sheath of anagen hair follicles of human scalp.
4.1. Pathogenesis of CLE
2.2. The hair follicle stem cell location Hair follicle stem cells are thought to be slow-cycling cells, with superior clonogenicity and proliferative capacity [5]. These cells are multipotent, capable of proliferating and giving rise to all types of hair, the epidermis and the sebaceous gland [6]. Several studies show that the slowestcycling keratinocytes, identified as label retaining cells, were concentrated in the bulge region of the human and rodent hair follicles [7,8], not in the lower outer root sheath or bulb. On the other hand, although most of the stem cells of the follicle are located at the bulge region, similar types of in vitro analyses by other investigators suggested that human hair follicle stem cells were located in the lower hair follicle below the level of the bulge [9]. Lyle et al. [10] demonstrated that the C8/144B monoclonal antibody, originally raised against a CD8 peptide [11] identified human adult hair follicle bulge cells. 2.3. Hair follicle stem cell markers One of the most useful positive markers for human bulge cells is CK15 [12]. The antibodies used for the detection of CK15 are derived from two different clones, LHK15 [13] and C8/144B [10]. The latter antibody reacts with cells of the outer root sheath of the hair follicle around the bulge region, but not with other parts of the hair follicle or the epidermis. It also stains a subset of cytotoxic lymphocytes. The LHK15 antibody has been shown to delineate the isthmus area; however, this antibody appears to have a more extensive immunostaining pattern; since the antibody stains the entire outer root sheath of the human hair follicle [13,14]. In addition to CK 15, CK 19 and CD200 in the bulge region can serve as positive markers for hair follicle stem cells. However these markers are not exclusively expressed in the bulge region [12].
LE is a systemic autoimmune disease of unknown etiology and may involve multiple, interacting genetics and environmental factors. Although clearly there is a link between the cutaneous and systemic manifestations of LE, often the skin flares independently [19]. The causes and pathogenic mechanisms responsible for CLE are not fully understood. Cellular and tissue damage play an important role in the initiation, development and persistence of the disease. Apoptosis is one of the potential etiologic and pathophysiologic processes fundamental to autoimmune diseases, in addition to other factors such as inflammation, infection, environmental factors and genetics [20]. In genetically prone individuals, minor imbalances in the feedback controls of Toll-like receptors expressed on dendritic cells have been associated with autoimmunity; the recognition of microbial stimuli by Toll-like receptors is essential for the production of inflammatory cytokines, chemokines that play a key role in the regulation of inflammatory reactions [21]. 4.2. Role of lymphocytes in scarring process in CLE The inflammatory infiltrate in the dermis is usually composed predominantly of T-lymphocytes. In this pathologic process, the pilosebaceous unit appears to be the primary target. Destruction of the epidermal and adnexal structures was closely associated with CD8+ T cells expressing the cytotoxic molecule granzyme B [22]. A significant number of T-lymphocytes expressing both CLA and chemokine receptor4 (CCR4) have been found in skin lesions and in peripheral blood of patients with scarring DLE [23]. Plasmacytoid dendritic cells (PDCs) are believed to play a central role in the pathogenesis of the disease by being an important source of interferon IFN α and β and this would subsequently lead to more selection and activation of autoreactive T cells [24]. 5. The stem cells of the hair follicle and scarring process in CCLE 5.1. Hair follicle and scarring alopecia The localization of these stem cells to the bulge area may explain why some types of inflammatory alopecia cause
476
K. Al-Refu, M. Goodfield / Autoimmunity Reviews 8 (2009) 474–477
alopecia areata is the massive inflammatory infiltrate in the peri-bulbar region of the hair follicles [29] which usually does not cause irreversible hair follicle damage. 5.2. Involvement of bulge region in primary scarring alopecia Due to the relative rarity of this type of alopecia, there have been a few studies on the pathogenesis of scarring alopecia in the human investigating the role of stem cells in this scarring process. LPP is one of the scarring inflammatory alopecias which has been investigated for the role of the bulge region in the pathogenesis of the scarring process [30]. This disease is characterized histologically, in the inflammatory stage, by the presence of a band like lymphocytic infiltrate at the bulge region with the lower portion of the follicle being spared [31]. A study by Mobini et al. [30] demonstrated that the proliferating stem cells, highlighted by Ki-67, showed a marked decrease in the bulge compared with uninvolved follicles or normal controls. Another study [32] on patients with primary cicatricial alopecia (15 patients, one of them with CCLE) also confirmed the previous finding of involvement of the bulge region of hair follicles in these patients by demonstrating the absence of follicular bulge cells (using CK15 as a marker for stem cells) in cases with moderate to heavy inflammation. 5.3. Involvement of the bulge region in CLE
Fig. 1. The bulge region of hair follicle as demonstrated by haematoxylin and eosin staining (a) and by immunohistochemistry (b). The site of the insertion of the arrector pili muscle is demonstrated by red arrows in both views. In both of these follicles the trochanter of hair follicles is prominent as demonstrated by black arrows.
permanent loss of hair (cicatricial alopecia) (such as DLE), while others (such as alopecia areata) are reversible (noncicatricial alopecia) [25]; compromising the integrity of the sebaceous gland and/or bulge is important in the development of the scarring process in the cicatricial alopecias. Selective destruction of the stem cell region in graft versus host disease, in which an inflammatory infiltrate involves the stem cells, can lead to follicular destruction [26]. The asebia mouse, which lacks one gene responsible for normal sebum production, provides a model for cicatricial alopecia [27]. An animal study in mice showed that male mice (the New Zealand Black/KN (NZB/KN)) may represent a suitable mouse model for autoimmune induced alopecia, with some similarities to the permanent alopecia seen in human DLE patients [28]. Hiroi et al. [28] demonstrated that the hair matrix region at the level of the bulb of the affected anagen hair follicles in the ageing male NZB/KN mice showed increased apoptosis and decreased proliferation (by using Ki-67 as a marker of proliferation). In contrast to irreversible alopecia that may be observed in CCLE and other types of cicatricial alopecia, alopecia areata is characterized by alopecia which is reversible. A characteristic histological finding in lesional skin from patients with
Until now there has been only one study [33] investigating the role of the bulge region in the pathogenesis of the scarring process in CLE (Al-Refu et al. [33]). We studied the reactivity of an antibody (C8/144B), which recognizes CK15, on skin biopsies (scalp and body lesions) from thirty-six CLE patients with discoid lesions. There was normal to moderate CK15 expression at the bulge region of hair follicles when surrounded by mild or moderate inflammatory infiltrate (CD8+), but in cases of severe inflammation, CK15 expression was weak or absent. The bulge region appears to be involved in this disease as part of broader involvement of the hair follicles; it is secondarily affected by the surrounding inflammatory cell infiltrate. Expression of C8/144B diminished and was then absent indicating either damage to stem cells or differentiation to help in the repair process. 6. Conclusion Although it has been demonstrated that stem cells have been involved in the primary cicatricial alopecia and in CLE, this involvement was secondary to the surrounding inflammatory process and not due to a primary insult in these cells. Further study is needed in the future for more assessment and to examine follicular pathology and cell kinetics. Further studies may be needed for this particular type of alopecia at electron microscopic level. This may answer some of the questions of what happens to the hair follicles in the variety of cases of cicatricial alopecia. It is unlikely that the pathology is the same in these diseases. Take-home messages • The pilosebaceous unit appears to be one of the targets of the inflammatory process in CLE, and it is possible that destruction
K. Al-Refu, M. Goodfield / Autoimmunity Reviews 8 (2009) 474–477
•
• •
•
•
of stem cells at the bulge region of hair follicle by the inflammatory infiltrate prevents the regeneration of the follicle. The anatomic boundaries of the bulge region of hair follicles in humans are ill defined when compared to mice, and this makes it necessary to use a specific stem cell marker which can delineate the bulge region. One of the most useful positive markers for human bulge cells is cytokeratin CK15. The bulge region appears to be involved in CLE (as demonstrated by using CK 15 as a marker of stem cells) as part of broader involvement of the hair follicles; it is secondarily affected by the surrounding inflammatory cell infiltrate. Expression of stem cells markers diminished and were then absent indicating either damage to stem cells or differentiation to help in the repair process. Follicular stem cell damage may be relevant in other scarring condition.
References [1] Wilson CL, Burge SM, Dean D, Dawber RP. Scarring alopecia in discoid lupus erythematosus. Br J Dermatol 1992;126:307–14. [2] Ohyama M, Terunuma A, Tock CL, Radonovich MF, Pise-Masison CA, Hopping SB, et al. Characterization and isolation of stem cell-enriched human hair follicle bulge cells. J Clin Invest 2006;116:249–60. [3] Cotsarelis G. Epithelial stem cells: a folliculocentric view. J Invest Dermatol 2006;126:1459–68. [4] Tiede S, Kloepper JE, Whiting DA, Paus R. the ‘follicular trochanter’: an epithelial compartment of the human hair follicle bulge region in need of further characterization. Br J Dermatol 2007;157:1013–6. [5] Lavker RM, Sun TT. Epidermal stem cells, properties, markers and location. Proc Natl Acad Sci USA 2000;97:13473–5. [6] Morris RJ, Liu Y, Marles L, Yang Z, Trempus C, Li S, et al. Capturing and profiling adult hair follicle stem cells. Nat Biotechnol 2004;22:411–7. [7] Morris RJ, Potten CS. Highly persistent label-retaining cells in the hair follicle of mice and their fate following induction of anagen. J Invest Dermatol 1999;112:470–5. [8] Taylor G, Lehrer MS, Jensen PJ, Sun TT, Lavker RM. Involvement of follicular stem cells in forming not only the follicle but also the epidermis. Cell 2000;102:451–61. [9] Moll I. Proliferative potential of different keratinocytes of plucked human hair follicles. J Invest Dermatol 1995;105:14–21. [10] Lyle S, Christofidou-Solomidou M, Liu Y, Elder DE, Albelda S, Cotsarelis G. The C8/144B monoclonal antibody recognizes cytokeratin 15 and defines the location of human hair follicle stem cells. J Cell Sci 1998;111:3179–88. [11] Mason DY, Cordell JL, Gaulard P, Tse AG, Brown MH. Immunohistochemical detection of human cytotoxic/suppressor T cells using antibodies to a CD8 peptide sequence. J Clin Pathol 1992;45:1084–8. [12] Kloepper JE, Tiede S, Brinckmann J, Reinhardt DP, Meyer W, Faessler R, et al. Immunophenotyping of the human bulge region: the quest to define useful in situ markers for human epithelial hair follicle stem cells and their niche. Exp Dermatol 2008;17:592–609.
477
[13] Waseem A, Dogan B, Tidman N, Alam Y, Purkis P, Jackson S, et al. Keratin 15 expression in stratified epithelia: downregulation in activated keratinocytes. J Invest Dermatol 1999;112:362–9. [14] Poblet E, Jiménez F, Godínez JM, Pascual-Martín A, Izeta A. The immunohistochemical expression of CD34 in human hair follicles: a comparative study with the bulge marker CK15. Clin Exp Dermatol 2006;31:807–12. [15] Gilliam JN, Sontheimer RD. Distinctive cutaneous subsets in the spectrum of lupus erythematosus. J Am Acad Dermatol 1981;4:471–5. [16] de Berker D, Dissaneyeka M, Burge S. The sequelae of chronic cutaneous lupus erythematosus. Lupus 1992;1:181–6. [17] Fabbri P, Amato L, Chiarini C, Moretti S, Massi D. Scarring alopecia in discoid lupus erythematosus: a clinical, histopathologic and immunopathologic study. Lupus 2004;13(6):455–62. [18] David-Bajar KM, Bennion SD, DeSpain JD, Golitz LE, Lee LA. Clinical, histologic, and immunofluorescent distinction between subacute cutaneous lupus erythematous and discoid lupus erythematous. J Invest Dermatol 1992;99:251–7. [19] Werth VP. Cutaneous lupus: insight into pathogenesis and disease classification. Bull NYU Hosp Jt Dis 2007;65:200–4. [20] Mackay IR, Leskovosek NV, Rose NR. Cell damage and autoimmunity: a critical appraisal. J Autoimmune 2008;30:5–11. [21] Granucci F, Zanoni I. Role of Toll like receptors-activated dendritic cells in the development of autoimmunity. Front Biosci 2008;13:4817–26. [22] Wenzel J, Uerlich M, Wörrenkämper E, Freutel S, Bieber T, Tüting T. Scarring skin lesions of discoic lupus erythematosus are characterized by high numbers of skin-homing cytotoxic lymphocytes associated with strong expression of the type 1 interferon-induced protein MxA. Br J Dermatol 2005;153:1011–5. [23] Wenzel J, Henze S, Wörrenkämper E, Basner-Tschakarjan E, SokolowskaWojdylo M, Steitz J, et al. Role of the chemokine receotor CCR4 and its ligand thymus- and activation-regulated chemokine/CCL17 for lymphocyte recruitment in cutaneous lupus erythematosus. J Invest Dermatol 2005;124:1241–8. [24] Farkas L, Beiske K, Lund-Johansen F, Brandtzaeg P, Jahnsen FL. Plasmacytoid dendritic cells (natural interferon-alpha/beta-producing cells) accumulate in cutaneous lupus erythematosus lesions. Am J Pathol 2001;159:237–43. [25] Paus R, Cotsarelis G. The biology of hair follicles. N Engl J Med 1999;341: 491–7. [26] Sale GE. Does graft versus host disease attack epithelial stem cells? Mol Med Today 1996;2:114–9. [27] Stenn KS. Insights from the asebia mouse: a molecular sebaceous gland defect leading to cicatricial alopecia. J Cutan Pathol 2001;28:445–7. [28] Hiroi A, Ito T, Seo N, Uede K, Yoshimasu T, Ito M, et al. Male New Zealand black/KN mice: a novel model for autoimmune-induced permanent alopecia. Br J Dermatol 2006;155:437–45. [29] Lu W, Shapiro J, Yu M, Barekatain A, Lo B, Finner A, et al. Alopecia areata: pathogenesis and potential for therapy. Expert Rev Mol Med 2006;8:1–19. [30] Mobini N, Tam S, Kamino H. Possible role of the bulge region in the pathogenesis of inflammatory scarring alopecia: lichen planopilaris as the prototype. J Cuta Pathol 2005;32:675–9. [31] Annessi G, Lambardo G, Gobello T, Puddu P. A clinicopathologic study of scarring alopecia due to lichen planus: comparison with scarring alopecia in discoid lupus erythematosus and pseudopelade. Am J Dermatopathol 1999;21:324–31. [32] Pozdnyakova O, Mahalingam M. Involvement of the bulge region in primary scarring alopecia. J Cut Pathol 2008;35:922–5. [33] Al-Refu K, Edward S, Ingham E, Goodfield M. Expression of the hair follicle stem cells detected by CK15 stain: implications for pathogenesis of scarring process in Cutaneous Lupus Erythematosus. Br J Dermatol in press.
The lack of anti-idiotypic antibodies, not the presence of the corresponding autoantibodies to glutamate decarboxylase, defines type 1 diabetes Autoantibodies to glutamate decarboxylaze 65 (GAD65Ab) are commonly believed to be a major characteristic for type 1 diabetes (T1D). In this study, Oak S. et al. (PNAS 2008; 105: 5471–76) investigated presence of GAD65Ab in healthy individuals (n =238) and first-degree relatives (FDRs) of T1D patients (n =27)who tested negative for GAD65Ab in conventional RIAs. Sera were applied to affinity columns coated with GAD65-specific mAbs to absorb anti-idiotypic antibodies (anti-Ids). The absorbed sera were analyzed for binding to GAD65 by RIAs. Both healthy individuals and FDRs present GAD65Ab that are inhibited by anti-Id, masking them in conventional detection methods. The presence of GAD65Ab-specific anti-Ids was confirmed by competitive ELISA. Remarkably, T1D patients (n =54) and Stiff Person Syndrome patients (n =8) show a specific lack of anti-Ids to disease-associated GAD65Ab epitopes. Purified anti-Ids from healthy individuals and FDRs inhibited the binding of GAD65Ab from T1D patients to GAD65. The authors conclude that masked GAD65Ab are present in the healthy population and that a lack of particular anti-Ids, rather than GAD65Ab per se, is a characteristic of T1D. The lack of these inhibitory antibodies may contribute to T cell activation by GAD65Ab.
Contents lists available at ScienceDirect
Autoimmunity Reviews j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / a u t r e v
Hair follicle stem cells in the pathogenesis of the scarring process in cutaneous lupus erythematosus Khitam Al-Refu a,⁎, Mark Goodfield a,b,1 a b
Department of Internal Medicine, School of Medicine, Mutah University, Karak, PO Box 51, post code 61710, Jordan Department of Dermatology, Leeds General Infirmary, Great George Street, Leeds, West Yorkshire, LS1 3EX, England, UK
a r t i c l e
i n f o
Available online 20 January 2009 Keywords: Cutaneous lupus erythematosus (CLE) Scar Stem cells of hair follicle
a b s t r a c t Lupus erythematosus (LE) is an autoimmune disease that can affect one or more internal organs (systemic LE [SLE]) as well as the skin (CLE). Common cutaneous subtypes of CLE are chronic CLE (CCLE) and subacute CLE (SCLE). CCLE is the only type of CLE which heals with scarring and this may affect any site in the body. The fact that inflammation in CCLE generally involves the bulge area of the follicles (where the stem cells reside) raises the possibility that damage to the stem cells may be one process leading to permanent loss of follicles. One of the most useful distinctive markers of the stem cells is cytokeratin 15 (CK15) and this has been used in some studies to demonstrate the involvement of the bulge region in the scarring process in primary cicatricial alopecia and DLE. The bulge region appears to be involved in the scarring process in CLE and other types of cicatricial alopecia as part of broader involvement of the hair follicles; it is secondarily affected by the surrounding inflammatory cell infiltrate. Expression of the stem cell marker CK15 diminished and was then absent indicating either damage to stem cells or differentiation to help in the repair process. © 2008 Elsevier B.V. All rights reserved.
Contents 1. 2.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The bulge region of the hair follicle, stem cell location and their specific markers 2.1. The bulge region of the hair follicle . . . . . . . . . . . . . . . . . . 2.2. The hair follicle stem cell location. . . . . . . . . . . . . . . . . . . 2.3. Hair follicle stem cell markers . . . . . . . . . . . . . . . . . . . . 3. The scarring response in CLE . . . . . . . . . . . . . . . . . . . . . . . . 4. Autoimmunity and scarring process in CLE . . . . . . . . . . . . . . . . . . 4.1. Pathogenesis of CLE . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Role of lymphocytes in scarring process in CLE . . . . . . . . . . . . . 5. The stem cells of the hair follicle and scarring process in CCLE . . . . . . . . 5.1. Hair follicle and scarring alopecia . . . . . . . . . . . . . . . . . . . 5.2. Involvement of bulge region in primary scarring alopecia . . . . . . . . 5.3. Involvement of the bulge region in CLE . . . . . . . . . . . . . . . . 6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Take-home messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
⁎ Corresponding author. Tel.: +962 795050339. E-mail addresses: [email protected] (K. Al-Refu), mark.goodfi[email protected] (M. Goodfield). 1 Tel.: +44 1132432799; fax: +44 1133926336. 1568-9972/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.autrev.2008.12.015
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. 475 . 475 . 475 . 475 . 475 . 475 . 475 . 475 . 475 . 475 . 475 . 476 . 476 . 476 . 476 . 477
K. Al-Refu, M. Goodfield / Autoimmunity Reviews 8 (2009) 474–477
475
1. Introduction
3. The scarring response in CLE
Lupus erythematosus (LE) is an autoimmune disease that can affect one or more internal organ (systemic LE [SLE]) as well as the skin (CLE). The common cutaneous subtypes are chronic CLE (CCLE) and subacute CLE (SCLE). The fact that inflammation in CCLE generally involves the bulge area of the follicles [1] raises the possibility that damage to the stem cells of the bulge region may be one process leading to permanent loss of follicles. This review considers the potential role of follicular stem cells in the pathogenesis of scarring process in CLE. 2. The bulge region of the hair follicle, stem cell location and their specific markers
The typical clinical manifestation of CCLE is discoid lupus erythematosus (DLE), and it is the only type of cutaneous lupus which heals with scarring [15]. This scarring process commonly involves the scalp and face, but may involve any site [16]. The main histopathologic aspects of DLE are appendageal destruction, follicular hyperkeratosis, lymphocytic infiltration, thickened basement membrane zone and basal vacuolar degeneration [17]. Loss of appendages can be considered as a characteristic feature of DLE; since it is not usually evident in acute or subacute forms of CLE [18]. The localization of the hair follicle stem cells to the bulge region of hair follicle may explain why the inflammatory process in CLE causes permanent alopecia.
2.1. The bulge region of the hair follicle
4. Autoimmunity and scarring process in CLE
The bulge region forms an area of the outer root sheath of both mouse and human hair follicles, located in the mid portion of the follicle, which is at the insertion of the arrector pili muscle (Fig. 1a,b). Although several lines of evidence have suggested that the bulge region also provides a niche for keratinocytes stem cells [2], anatomic boundaries are ill defined [3]. Recently, Tiede et al. [4] have identified a prominent ‘follicular trochanter’-like epithelial structure in the bulge region of the outer root sheath of anagen hair follicles of human scalp.
4.1. Pathogenesis of CLE
2.2. The hair follicle stem cell location Hair follicle stem cells are thought to be slow-cycling cells, with superior clonogenicity and proliferative capacity [5]. These cells are multipotent, capable of proliferating and giving rise to all types of hair, the epidermis and the sebaceous gland [6]. Several studies show that the slowestcycling keratinocytes, identified as label retaining cells, were concentrated in the bulge region of the human and rodent hair follicles [7,8], not in the lower outer root sheath or bulb. On the other hand, although most of the stem cells of the follicle are located at the bulge region, similar types of in vitro analyses by other investigators suggested that human hair follicle stem cells were located in the lower hair follicle below the level of the bulge [9]. Lyle et al. [10] demonstrated that the C8/144B monoclonal antibody, originally raised against a CD8 peptide [11] identified human adult hair follicle bulge cells. 2.3. Hair follicle stem cell markers One of the most useful positive markers for human bulge cells is CK15 [12]. The antibodies used for the detection of CK15 are derived from two different clones, LHK15 [13] and C8/144B [10]. The latter antibody reacts with cells of the outer root sheath of the hair follicle around the bulge region, but not with other parts of the hair follicle or the epidermis. It also stains a subset of cytotoxic lymphocytes. The LHK15 antibody has been shown to delineate the isthmus area; however, this antibody appears to have a more extensive immunostaining pattern; since the antibody stains the entire outer root sheath of the human hair follicle [13,14]. In addition to CK 15, CK 19 and CD200 in the bulge region can serve as positive markers for hair follicle stem cells. However these markers are not exclusively expressed in the bulge region [12].
LE is a systemic autoimmune disease of unknown etiology and may involve multiple, interacting genetics and environmental factors. Although clearly there is a link between the cutaneous and systemic manifestations of LE, often the skin flares independently [19]. The causes and pathogenic mechanisms responsible for CLE are not fully understood. Cellular and tissue damage play an important role in the initiation, development and persistence of the disease. Apoptosis is one of the potential etiologic and pathophysiologic processes fundamental to autoimmune diseases, in addition to other factors such as inflammation, infection, environmental factors and genetics [20]. In genetically prone individuals, minor imbalances in the feedback controls of Toll-like receptors expressed on dendritic cells have been associated with autoimmunity; the recognition of microbial stimuli by Toll-like receptors is essential for the production of inflammatory cytokines, chemokines that play a key role in the regulation of inflammatory reactions [21]. 4.2. Role of lymphocytes in scarring process in CLE The inflammatory infiltrate in the dermis is usually composed predominantly of T-lymphocytes. In this pathologic process, the pilosebaceous unit appears to be the primary target. Destruction of the epidermal and adnexal structures was closely associated with CD8+ T cells expressing the cytotoxic molecule granzyme B [22]. A significant number of T-lymphocytes expressing both CLA and chemokine receptor4 (CCR4) have been found in skin lesions and in peripheral blood of patients with scarring DLE [23]. Plasmacytoid dendritic cells (PDCs) are believed to play a central role in the pathogenesis of the disease by being an important source of interferon IFN α and β and this would subsequently lead to more selection and activation of autoreactive T cells [24]. 5. The stem cells of the hair follicle and scarring process in CCLE 5.1. Hair follicle and scarring alopecia The localization of these stem cells to the bulge area may explain why some types of inflammatory alopecia cause
476
K. Al-Refu, M. Goodfield / Autoimmunity Reviews 8 (2009) 474–477
alopecia areata is the massive inflammatory infiltrate in the peri-bulbar region of the hair follicles [29] which usually does not cause irreversible hair follicle damage. 5.2. Involvement of bulge region in primary scarring alopecia Due to the relative rarity of this type of alopecia, there have been a few studies on the pathogenesis of scarring alopecia in the human investigating the role of stem cells in this scarring process. LPP is one of the scarring inflammatory alopecias which has been investigated for the role of the bulge region in the pathogenesis of the scarring process [30]. This disease is characterized histologically, in the inflammatory stage, by the presence of a band like lymphocytic infiltrate at the bulge region with the lower portion of the follicle being spared [31]. A study by Mobini et al. [30] demonstrated that the proliferating stem cells, highlighted by Ki-67, showed a marked decrease in the bulge compared with uninvolved follicles or normal controls. Another study [32] on patients with primary cicatricial alopecia (15 patients, one of them with CCLE) also confirmed the previous finding of involvement of the bulge region of hair follicles in these patients by demonstrating the absence of follicular bulge cells (using CK15 as a marker for stem cells) in cases with moderate to heavy inflammation. 5.3. Involvement of the bulge region in CLE
Fig. 1. The bulge region of hair follicle as demonstrated by haematoxylin and eosin staining (a) and by immunohistochemistry (b). The site of the insertion of the arrector pili muscle is demonstrated by red arrows in both views. In both of these follicles the trochanter of hair follicles is prominent as demonstrated by black arrows.
permanent loss of hair (cicatricial alopecia) (such as DLE), while others (such as alopecia areata) are reversible (noncicatricial alopecia) [25]; compromising the integrity of the sebaceous gland and/or bulge is important in the development of the scarring process in the cicatricial alopecias. Selective destruction of the stem cell region in graft versus host disease, in which an inflammatory infiltrate involves the stem cells, can lead to follicular destruction [26]. The asebia mouse, which lacks one gene responsible for normal sebum production, provides a model for cicatricial alopecia [27]. An animal study in mice showed that male mice (the New Zealand Black/KN (NZB/KN)) may represent a suitable mouse model for autoimmune induced alopecia, with some similarities to the permanent alopecia seen in human DLE patients [28]. Hiroi et al. [28] demonstrated that the hair matrix region at the level of the bulb of the affected anagen hair follicles in the ageing male NZB/KN mice showed increased apoptosis and decreased proliferation (by using Ki-67 as a marker of proliferation). In contrast to irreversible alopecia that may be observed in CCLE and other types of cicatricial alopecia, alopecia areata is characterized by alopecia which is reversible. A characteristic histological finding in lesional skin from patients with
Until now there has been only one study [33] investigating the role of the bulge region in the pathogenesis of the scarring process in CLE (Al-Refu et al. [33]). We studied the reactivity of an antibody (C8/144B), which recognizes CK15, on skin biopsies (scalp and body lesions) from thirty-six CLE patients with discoid lesions. There was normal to moderate CK15 expression at the bulge region of hair follicles when surrounded by mild or moderate inflammatory infiltrate (CD8+), but in cases of severe inflammation, CK15 expression was weak or absent. The bulge region appears to be involved in this disease as part of broader involvement of the hair follicles; it is secondarily affected by the surrounding inflammatory cell infiltrate. Expression of C8/144B diminished and was then absent indicating either damage to stem cells or differentiation to help in the repair process. 6. Conclusion Although it has been demonstrated that stem cells have been involved in the primary cicatricial alopecia and in CLE, this involvement was secondary to the surrounding inflammatory process and not due to a primary insult in these cells. Further study is needed in the future for more assessment and to examine follicular pathology and cell kinetics. Further studies may be needed for this particular type of alopecia at electron microscopic level. This may answer some of the questions of what happens to the hair follicles in the variety of cases of cicatricial alopecia. It is unlikely that the pathology is the same in these diseases. Take-home messages • The pilosebaceous unit appears to be one of the targets of the inflammatory process in CLE, and it is possible that destruction
K. Al-Refu, M. Goodfield / Autoimmunity Reviews 8 (2009) 474–477
•
• •
•
•
of stem cells at the bulge region of hair follicle by the inflammatory infiltrate prevents the regeneration of the follicle. The anatomic boundaries of the bulge region of hair follicles in humans are ill defined when compared to mice, and this makes it necessary to use a specific stem cell marker which can delineate the bulge region. One of the most useful positive markers for human bulge cells is cytokeratin CK15. The bulge region appears to be involved in CLE (as demonstrated by using CK 15 as a marker of stem cells) as part of broader involvement of the hair follicles; it is secondarily affected by the surrounding inflammatory cell infiltrate. Expression of stem cells markers diminished and were then absent indicating either damage to stem cells or differentiation to help in the repair process. Follicular stem cell damage may be relevant in other scarring condition.
References [1] Wilson CL, Burge SM, Dean D, Dawber RP. Scarring alopecia in discoid lupus erythematosus. Br J Dermatol 1992;126:307–14. [2] Ohyama M, Terunuma A, Tock CL, Radonovich MF, Pise-Masison CA, Hopping SB, et al. Characterization and isolation of stem cell-enriched human hair follicle bulge cells. J Clin Invest 2006;116:249–60. [3] Cotsarelis G. Epithelial stem cells: a folliculocentric view. J Invest Dermatol 2006;126:1459–68. [4] Tiede S, Kloepper JE, Whiting DA, Paus R. the ‘follicular trochanter’: an epithelial compartment of the human hair follicle bulge region in need of further characterization. Br J Dermatol 2007;157:1013–6. [5] Lavker RM, Sun TT. Epidermal stem cells, properties, markers and location. Proc Natl Acad Sci USA 2000;97:13473–5. [6] Morris RJ, Liu Y, Marles L, Yang Z, Trempus C, Li S, et al. Capturing and profiling adult hair follicle stem cells. Nat Biotechnol 2004;22:411–7. [7] Morris RJ, Potten CS. Highly persistent label-retaining cells in the hair follicle of mice and their fate following induction of anagen. J Invest Dermatol 1999;112:470–5. [8] Taylor G, Lehrer MS, Jensen PJ, Sun TT, Lavker RM. Involvement of follicular stem cells in forming not only the follicle but also the epidermis. Cell 2000;102:451–61. [9] Moll I. Proliferative potential of different keratinocytes of plucked human hair follicles. J Invest Dermatol 1995;105:14–21. [10] Lyle S, Christofidou-Solomidou M, Liu Y, Elder DE, Albelda S, Cotsarelis G. The C8/144B monoclonal antibody recognizes cytokeratin 15 and defines the location of human hair follicle stem cells. J Cell Sci 1998;111:3179–88. [11] Mason DY, Cordell JL, Gaulard P, Tse AG, Brown MH. Immunohistochemical detection of human cytotoxic/suppressor T cells using antibodies to a CD8 peptide sequence. J Clin Pathol 1992;45:1084–8. [12] Kloepper JE, Tiede S, Brinckmann J, Reinhardt DP, Meyer W, Faessler R, et al. Immunophenotyping of the human bulge region: the quest to define useful in situ markers for human epithelial hair follicle stem cells and their niche. Exp Dermatol 2008;17:592–609.
477
[13] Waseem A, Dogan B, Tidman N, Alam Y, Purkis P, Jackson S, et al. Keratin 15 expression in stratified epithelia: downregulation in activated keratinocytes. J Invest Dermatol 1999;112:362–9. [14] Poblet E, Jiménez F, Godínez JM, Pascual-Martín A, Izeta A. The immunohistochemical expression of CD34 in human hair follicles: a comparative study with the bulge marker CK15. Clin Exp Dermatol 2006;31:807–12. [15] Gilliam JN, Sontheimer RD. Distinctive cutaneous subsets in the spectrum of lupus erythematosus. J Am Acad Dermatol 1981;4:471–5. [16] de Berker D, Dissaneyeka M, Burge S. The sequelae of chronic cutaneous lupus erythematosus. Lupus 1992;1:181–6. [17] Fabbri P, Amato L, Chiarini C, Moretti S, Massi D. Scarring alopecia in discoid lupus erythematosus: a clinical, histopathologic and immunopathologic study. Lupus 2004;13(6):455–62. [18] David-Bajar KM, Bennion SD, DeSpain JD, Golitz LE, Lee LA. Clinical, histologic, and immunofluorescent distinction between subacute cutaneous lupus erythematous and discoid lupus erythematous. J Invest Dermatol 1992;99:251–7. [19] Werth VP. Cutaneous lupus: insight into pathogenesis and disease classification. Bull NYU Hosp Jt Dis 2007;65:200–4. [20] Mackay IR, Leskovosek NV, Rose NR. Cell damage and autoimmunity: a critical appraisal. J Autoimmune 2008;30:5–11. [21] Granucci F, Zanoni I. Role of Toll like receptors-activated dendritic cells in the development of autoimmunity. Front Biosci 2008;13:4817–26. [22] Wenzel J, Uerlich M, Wörrenkämper E, Freutel S, Bieber T, Tüting T. Scarring skin lesions of discoic lupus erythematosus are characterized by high numbers of skin-homing cytotoxic lymphocytes associated with strong expression of the type 1 interferon-induced protein MxA. Br J Dermatol 2005;153:1011–5. [23] Wenzel J, Henze S, Wörrenkämper E, Basner-Tschakarjan E, SokolowskaWojdylo M, Steitz J, et al. Role of the chemokine receotor CCR4 and its ligand thymus- and activation-regulated chemokine/CCL17 for lymphocyte recruitment in cutaneous lupus erythematosus. J Invest Dermatol 2005;124:1241–8. [24] Farkas L, Beiske K, Lund-Johansen F, Brandtzaeg P, Jahnsen FL. Plasmacytoid dendritic cells (natural interferon-alpha/beta-producing cells) accumulate in cutaneous lupus erythematosus lesions. Am J Pathol 2001;159:237–43. [25] Paus R, Cotsarelis G. The biology of hair follicles. N Engl J Med 1999;341: 491–7. [26] Sale GE. Does graft versus host disease attack epithelial stem cells? Mol Med Today 1996;2:114–9. [27] Stenn KS. Insights from the asebia mouse: a molecular sebaceous gland defect leading to cicatricial alopecia. J Cutan Pathol 2001;28:445–7. [28] Hiroi A, Ito T, Seo N, Uede K, Yoshimasu T, Ito M, et al. Male New Zealand black/KN mice: a novel model for autoimmune-induced permanent alopecia. Br J Dermatol 2006;155:437–45. [29] Lu W, Shapiro J, Yu M, Barekatain A, Lo B, Finner A, et al. Alopecia areata: pathogenesis and potential for therapy. Expert Rev Mol Med 2006;8:1–19. [30] Mobini N, Tam S, Kamino H. Possible role of the bulge region in the pathogenesis of inflammatory scarring alopecia: lichen planopilaris as the prototype. J Cuta Pathol 2005;32:675–9. [31] Annessi G, Lambardo G, Gobello T, Puddu P. A clinicopathologic study of scarring alopecia due to lichen planus: comparison with scarring alopecia in discoid lupus erythematosus and pseudopelade. Am J Dermatopathol 1999;21:324–31. [32] Pozdnyakova O, Mahalingam M. Involvement of the bulge region in primary scarring alopecia. J Cut Pathol 2008;35:922–5. [33] Al-Refu K, Edward S, Ingham E, Goodfield M. Expression of the hair follicle stem cells detected by CK15 stain: implications for pathogenesis of scarring process in Cutaneous Lupus Erythematosus. Br J Dermatol in press.
The lack of anti-idiotypic antibodies, not the presence of the corresponding autoantibodies to glutamate decarboxylase, defines type 1 diabetes Autoantibodies to glutamate decarboxylaze 65 (GAD65Ab) are commonly believed to be a major characteristic for type 1 diabetes (T1D). In this study, Oak S. et al. (PNAS 2008; 105: 5471–76) investigated presence of GAD65Ab in healthy individuals (n =238) and first-degree relatives (FDRs) of T1D patients (n =27)who tested negative for GAD65Ab in conventional RIAs. Sera were applied to affinity columns coated with GAD65-specific mAbs to absorb anti-idiotypic antibodies (anti-Ids). The absorbed sera were analyzed for binding to GAD65 by RIAs. Both healthy individuals and FDRs present GAD65Ab that are inhibited by anti-Id, masking them in conventional detection methods. The presence of GAD65Ab-specific anti-Ids was confirmed by competitive ELISA. Remarkably, T1D patients (n =54) and Stiff Person Syndrome patients (n =8) show a specific lack of anti-Ids to disease-associated GAD65Ab epitopes. Purified anti-Ids from healthy individuals and FDRs inhibited the binding of GAD65Ab from T1D patients to GAD65. The authors conclude that masked GAD65Ab are present in the healthy population and that a lack of particular anti-Ids, rather than GAD65Ab per se, is a characteristic of T1D. The lack of these inhibitory antibodies may contribute to T cell activation by GAD65Ab.