Successful treatment of alopecia areata-like hair loss with the contact sensitizer squaric acid dibutylester (SADBE) in C3H/HeJ mice

Altered T cell subpopulations and serum anti-TYRP2 and tyrosinase antibodies in the acute and chronic phase of alopecia areata in the C3H/HeJ mouse model

BACKGROUND

C3H/HeJ mouse models progress gradually in hair loss from acute to chronic phase and reflect the symptoms of patients with alopecia areata (AA). However, the underlying pathological characteristics alteration associated with disease progression and autoantigens remain unclear.

OBJECTIVE

We aimed at elucidating the pathological differences between acute and chronic-AA in the C3H/HeJ mouse model.

METHODS

We analyzed populations of PBMCs, skin-draining lymph node (SDLN) cells, and cutaneous cells of AA mice using flow cytometry. The cytokine and chemokine expressions in the serum and skin were determined using multiplex assay and qPCR. The antibody serum levels were determined using ELISA and the antigen-specific T cells were detected using the MHC class I tetramer.

RESULTS

The CD8⁺NKG2D⁺ T and CD8⁺ T_EM cell percentage in the chronic-AA SDLNs or among the unaffected and acute-AA mice PBMCs increased. The Th1 and CD4⁺ T_EM cell percentage in the SDLNs and among PBMCs increased in the unaffected and AA mice. The percentage of CD8⁺ T_EM/T_RM cells and MHC class I expression increased in the lesions of acute-AA or the non-lesions and lesions of chronic-AA. The Th1 cells, dendritic cell-related cytokines, CD11c⁺ cells and MHC class II expression increased in the skin of AA mice. The antibody levels and TYRP2 and tyrosinase-specific CD8⁺ T cell percentages were upregulated in AA mice.

CONCLUSION

These results suggest that the CD8⁺ and CD4⁺ T cell subpopulations, cytokine and chemokine expressions differ between the disease phases. Moreover, TYRP2 and tyrosinase are potential autoreactive targets in the AA mouse model.

A "hair-raising" history of alopecia areata

A 3500-year-old papyrus from ancient Egypt provides a list of treatments for many diseases including "bite hair loss," most likely alopecia areata (AA). The treatment of AA remained largely unchanged for over 1500 years. In 30 CE, Celsus described AA presenting as scalp alopecia in spots or the "windings of a snake" and suggested treatment with caustic compounds and scarification. The first "modern" description of AA came in 1813, though treatment still largely employed caustic agents. From the mid-19th century onwards, various hypotheses of AA development were put forward including infectious microbes (1843), nerve defects (1858), physical trauma and psychological stress (1881), focal inflammation (1891), diseased teeth (1902), toxins (1912) and endocrine disorders (1913). The 1950s brought new treatment developments with the first use of corticosteroid compounds (1952), and the first suggestion that AA was an autoimmune disease (1958). Research progressively shifted towards identifying hair follicle-specific autoantibodies (1995). The potential role of lymphocytes in AA was made implicit with immunohistological studies (1980s). However, studies confirming their functional role were not published until the development of rodent models (1990s). Genetic studies, particularly genome-wide association studies, have now come to the forefront and open up a new era of AA investigation (2000s). Today, AA research is actively focused on genetics, the microbiome, dietary modulators, the role of atopy, immune cell types in AA pathogenesis, primary antigenic targets, mechanisms by which immune cells influence hair growth, and of course the development of new treatments based on these discoveries.

Immunoregulatory Effects of Myeloid-Derived Suppressor Cell Exosomes in Mouse Model of Autoimmune Alopecia Areata

The treatment of autoimmune diseases still poses a major challenge, frequently relying on non-specific immunosuppressive drugs. Current efforts aim at reestablishing self tolerance using immune cells with suppressive activity like the regulatory T cells (Treg) or the myeloid-derived suppressor cells (MDSC). We have demonstrated therapeutic efficacy of MDSC in mouse Alopecia Areata (AA). In the same AA model, we now asked whether MDSC exosomes (MDSC-Exo) can replace MDSC. MDSC-Exo from bone marrow cells (BMC) cultures of healthy donors could substantially facilitate treatment. With knowledge on MDSC-Exo being limited, their suitability needs to be verified in advance. Protein marker profiles suggest comparability of BMC- to ex vivo collected inflammatory MDSC/MDSC-Exo in mice with a chronic contact dermatitis, which is a therapeutic option in AA. Proteome analyses substantiated a large overlap of function-relevant molecules in MDSC and MDSC-Exo. Furthermore, MDSC-Exo are taken up by T cells, macrophages, NK, and most avidly by Treg and MDSC-Exo uptake exceeds binding of MDSC themselves. In AA mice, MDSC-Exo preferentially target skin-draining lymph nodes and cells in the vicinity of remnant hair follicles. MDSC-Exo uptake is accompanied by a strong increase in Treg, reduced T helper proliferation, mitigated cytotoxic activity, and a slight increase in lymphocyte apoptosis. Repeated MDSC-Exo application in florid AA prevented progression and sufficed for partial hair regrowth. Deep sequencing of lymphocyte mRNA from these mice revealed a significant increase in immunoregulatory mRNA, including FoxP3 and arginase 1. Downregulated mRNA was preferentially engaged in prohibiting T cell hyperreactivity. Taken together, proteome analysis provided important insights into potential MDSC-Exo activities, these Exo preferentially homing into AA-affected organs. Most importantly, changes in leukocyte mRNA seen after treatment of AA mice with MDSC-Exo sustainably supports the strong impact on the adaptive and the non-adaptive immune system, with Treg expansion being a dominant feature. Thus, MDSC-Exo could potentially serve as therapeutic agents in treating AA and other autoimmune diseases.

Novel therapies for alopecia areata: The era of rational drug development

Treatments for alopecia areata (AA) have evolved over the decades from broad and nonspecific therapies to those that are now more targeted and rationally selected. This was achieved by means of close cooperation and communication between clinicians and basic scientists, which resulted in the elucidation and understanding of the unique pathophysiology of AA. In this review we discuss this evolution and how novel therapies for AA have changed over the decades, what we have in our current arsenal of drugs for this potentially devastating disease, and what the future holds.

Alopecia Areata in C3H/HeJ Mice Involves Leukocyte-mediated Root Sheath Disruption in Advance of Overt Hair Loss

Alopecia areata (AA) can be induced in C3H/HeJ mice by grafting full-thickness AA-affected skin. An 8- to 12-week delay between surgery and overt hair loss onset provides an opportunity to examine disease pathogenesis. Normal haired C3H/HeJ mice were sham-grafted or grafted with AA-affected skin. Mice were euthanatized 2, 4, 6, 8, 10, and 12 weeks after surgery along with chronic AA-affected mice as a positive control. Until 6 weeks after grafting, inflammation was only evident around anagen-stage hair follicles in host skin adjacent to but not distant from the AA-affected graft. From 8 weeks on, AA-grafted but not sham-grafted mice exhibited a diffuse dermal inflammation at distant sites that progressively focused on anagen-stage hair follicles at 10 and 12 weeks. Perifollicular inflammation was primarily composed of CD4+ and CD8+ cells associated with follicular epithelium intercellular adhesion molecule -1 expression. Only CD8+ cells penetrated intrafollicularly by 12 weeks after surgery, although both CD4+ and CD8+ intrafollicular cells were observed in chronic AA-affected mice. Under electron microscopy, intrafollicular lymphocyte and macrophage infiltration associated with hair follicle dystrophy was prominent 10 weeks after surgery, primarily within the differentiating outer and inner root sheaths. This study shows that focal follicular inflammation develops some time in advance of overt hair loss and focuses on the differentiating root sheaths in C3H/HeJ mice. The severity of inflammation and the degree of hair follicle dystrophy induced by the infiltrate appear to reach a threshold level before overt hair loss occurs.

Alopecia areata: Animal models illuminate autoimmune pathogenesis and novel immunotherapeutic strategies

One of the most common human autoimmune diseases, alopecia areata (AA), is characterized by sudden, often persisting and psychologically devastating hair loss. Animal models have helped greatly to elucidate critical cellular and molecular immune pathways in AA. The two most prominent ones are inbred C3H/HeJ mice which develop an AA-like hair phenotype spontaneously or after experimental induction, and healthy human scalp skin xenotransplanted onto SCID mice, in which a phenocopy of human AA is induced by injecting IL-2-stimulated PBMCs enriched for CD56+/NKG2D+ cells intradermally. The current review critically examines the pros and cons of the available AA animal models and how they have shaped our understanding of AA pathobiology, and the development of new therapeutic strategies. AA is thought to arise when the hair follicle's (HF) natural immune privilege (IP) collapses, inducing ectopic MHC class I expression in the HF epithelium and autoantigen presentation to autoreactive CD8+ T cells. In common with other autoimmune diseases, upregulation of IFN-γ and IL-15 is critically implicated in AA pathogenesis, as are NKG2D and its ligands, MICA, and ULBP3. The C3H/HeJ mouse model was used to identify key immune cell and molecular principles in murine AA, and proof-of-principle that Janus kinase (JAK) inhibitors are suitable agents for AA management in vivo, since both IFN-γ and IL-15 signal via the JAK pathway. Instead, the humanized mouse model of AA has been used to demonstrate the previously hypothesized key role of CD8+ T cells and NKG2D+ cells in AA pathogenesis and to discover human-specific pharmacologic targets like the potassium channel Kv1.3, and to show that the PDE4 inhibitor, apremilast, inhibits AA development in human skin. As such, AA provides a model disease, in which to contemplate general challenges, opportunities, and limitations one faces when selecting appropriate animal models in preclinical research for human autoimmune diseases.

Effectiveness of the combinational treatment of Laminaria japonica and Cistanche tubulosa extracts in hair growth

Since scalp hair loss has increased recently even in young people, seriously affecting individual's quality of life, the hair growth-stimulating effects of Laminaria japonica extract (LJE) and Cistanche tubulosa extract (CTE) were investigated. After confirming anagen phase of follicles under shaving, male C57BL/6 mice were dermally applied with 3% Minoxidil or orally administered with the combinations of LJE and CTE for 21 days. Minoxidil promoted the hair regrowth and increased γ-glutamyl transpeptidase (γ-GTP) and alkaline phosphatase (ALP) activities. In addition, Minoxidil up-regulated epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) levels. Co-administration of LJE and CTE at 54 mg/kg LJE plus 162 mg/kg CTE exerted synergistic promoting effects on the hair regrowth, comparable to 3% Minoxidil. LJE preferentially enhanced ALP activity, while CTE increased both γ-GTP and ALP activities as well as EGF and VEGF expressions. In vivo air pouch inflammation model, carrageenan-induced vascular exudation and increased nitric oxide and prostaglandin E₂ concentrations in the exudates were synergistically suppressed by co-administration of LJE and CTE. In addition, inflammatory cell infiltration was substantially inhibited by the combinational treatment. The results suggest that combinational oral treatment with LJE and CTE in appropriate doses and ratios prevent hair loss and improve alopecia, which might be in part mediated by their anti-inflammatory activities.

Be squared: expanding the horizon of squaric acid-mediated conjugations

Squaric acid diesters can be applied as reagents to couple two amino-functional compounds. Consecutive coupling of two amines allows the synthesis of asymmetric squaric acid bisamides with either low molecular weight compounds but also biomolecules or polymers. The key feature of the squaric acid diester mediated coupling is the reduced reactivity of the resulting ester-amide after the first amidation step of the diester. This allows the sequential amidation and generation of asymmetric squaramides with high selectivity and in high yields. This article gives an overview of the well-established squaric acid diester mediated coupling reactions for glycoconjugates and presents recent advances that aim to expand this very versatile reaction protocol to the modification of peptides and proteins.

Delayed type hypersensitivity-induced myeloid-derived suppressor cells regulate autoreactive T cells

Mild but efficient treatments of autoimmune diseases are urgently required. One such therapy, long-term maintenance of chronic delayed type hypersensitivity, has been described for alopecia areata (AA), a hair follicle-affecting autoimmune disease. The molecular mechanisms underlying the therapeutic efficacy are unknown, but may involve myeloid-derived suppressor cells (MDSCs). AA-affected mice were treated with squaric acid dibutyl ester (SADBE). The immunoreactivity of SADBE-treated AA lymphocytes and of AA lymphocytes co-cultured with SADBE-induced MDSCs was analyzed. The curative effect of SADBE was abolished by all-transretinoic acid, which drives MDSCs into differentiation, confirming a central role for MDSCs in therapeutic SADBE treatment. SADBE and SADBE-induced MDSCs strongly interfered with sustained autoreactive T-cell proliferation in response to AA skin lysate (autoantigen), which was accompanied by weak ζ-chain down-regulation and strongly impaired Lck activation. In contrast, activation of the mitochondrial apoptosis pathway and blockade of the anti-apoptotic PI3K/Akt pathway by SADBE-induced MDSCs did not require T-cell receptor engagement. Apoptosis induction correlated with high TNF-α expression in SADBE-induced MDSCs and elevated TNFRI levels in AA lymphocytes. SADBE-induced MDSCs interfere with persisting autoreactive T-cell proliferation and promote apoptosis of these T cells, which qualifies MDSCs induced and maintained by chronic delayed type hypersensitivity reactions as promising therapeutics in organ-related autoimmune diseases.

Diphencyprone and topical tacrolimus as two topical immunotherapeutic modalities. Are they effective in the treatment of alopecia areata among Egyptian patients? A study using CD4, CD8 and MHC II as markers

OBJECTIVE

To evaluate the efficacy of two topically applied immunomodulative agents through the detection of lymphocyte subsets using monoclonal antibodies against CD4, CD8 and MHC II.

METHODS

Fifty patients from the Departments of Medical Biochemistry, Dermatology and Pathology at Cairo University with different degrees of alopecia areata (AA) were included in this study. They were classified into two groups each of 25 patients. Each patient was treated with the immunomodulative agent on one side of the scalp and the other side was left as a control. Biopsies were taken from all patients at the beginning of treatment and at the end of the study. Tissue specimens were prepared for histologic and immunophenotypic analysis. The main outcome measures were the uses of diphencyprone (DPCP) and topical tacrolimus as two topical immunotherapeutic modalities in the treatment of AA.

RESULTS

A clinical response of 68% was achieved in group A (treated with DPCP) while group B (treated with 0.1% tacrolimus) showed an insignificant clinical response. Decreased expression of CD4 and increased expression of CD8 and MHC II was detected in the post-treated areas compared with pretreated areas in cases treated with DCPC. In tacrolimus-treated cases, there was a decrease in CD4 and MHC II, with no change in CD8 between the pre- and post-treated areas.

CONCLUSION

DCPC is one of the most accepted therapeutic modalities in the treatment of AA, with a favourable prognosis among patchy hair loss. MHC II expression was the one correlating with clinical response. Tacrolimus, though beneficial in other dermatoses, could not be considered effective in the treatment of AA.

The C3H/HeJ mouse and DEBR rat models for alopecia areata: review of preclinical drug screening approaches and results

The C3H/HeJ inbred mouse strain and the Dundee Experimental Bald Rat (DEBR) strain spontaneously develop adult onset alopecia areata (AA), a cell-mediated disease directed against actively growing hair follicles. The low frequency of AA and the inability to predict the stage of AA as it evolves in the naturally occuring C3H/HeJ model of AA can be converted into a highly predictable system by grafting full thickness skin from AA-affected mice to normal haired mice of the same strain. The rat DEBR model develops spontaneous AA at a higher frequency than in the mouse model but they are more expensive to use in drug studies owing to their larger size. Regardless of the shortcomings of either model, these rodent models can be used succesfully to screen novel or approved drugs for efficacy to treat human AA. As the pathogenesis of AA follows the canonical lymphocytic co-stimulatory cascade in the mouse AA model, it can be used to screen compounds potentially useful to treat a variety of cell-mediated diseases. Efficacy of various agents can easily be screened by simply observing the presence, rate, and cosmetic acceptability of hair regrowth. More sophisticated assays can refine how the drugs induce hair regrowth and evaluate the underlying pathogenesis of AA. Some drugs commonly used to treat human AA patients work equally as well in both rodent models validating their usefulness as models for drug efficacy and safety for humanAA.

Controlled delivery of T-box21 small interfering RNA ameliorates autoimmune alopecia (Alopecia Areata) in a C3H/HeJ mouse model

Autoimmune alopecia (alopecia areata) is considered to be triggered by a collapse of immune privilege in hair follicles. Here we confirmed that infiltrating CD4 T lymphocytes around hair follicles of patients with alopecia areata were primarily CCR5-positive with few CCR4-positive cells, suggesting a dominant role of Th1 cells in the alopecic lesion. Given this finding, we sought to elucidate the effect of cytokine therapy in C3H/HeJ mice, a mouse model of alopecia areata, by applying recombinant interleukin-4 and neutralizing anti-interferon-gamma antibody. We found that local injections of both interleukin-4 and neutralizing anti-interferon-gamma antibody effectively treated alopecia in C3H/HeJ mice. Results from immunohistochemistry and semiquantitative reverse transcription-polymerase chain reaction demonstrated that intralesional injection of interleukin-4 suppressed CD8 T cell infiltrates around the hair follicles and repressed enhanced interferon-gamma mRNA expression in the affected alopecic skin. Furthermore, Th1 transcription factor T-box21 small interfering RNAs conjugated to cationized gelatin showed mitigating effects on alopecia in C3H/HeJ mice, resulting in the restoration of hair shaft elongation. Taken together, the use of gelatin-small interfering RNA conjugates promises to be a novel, efficient, and safe tool as an alternative gene therapy for the treatment of various human diseases. To our knowledge, this is the first report of effective controlled delivery of small interfering RNA using biodegradable cationized gelatin microspheres in an animal model of disease.

Interleukin-6 cytokine family member oncostatin M is a hair-follicle-expressed factor with hair growth inhibitory properties

The activation of receptor complexes containing glycoprotein 130 (gp130) identifies the interleukin (IL)-6 cytokine family. We examined members of this family for their expression and activity in hair follicles. Quantitative polymerase chain reaction using mRNA derived from microdissected, anagen-stage human hair follicles and comparison to non-follicular skin epithelium revealed higher levels of IL-6 (15.5-fold) and oncostatin M (OSM, 3.4-fold) in hair follicles. In contrast, expression of all mRNAs coding for IL-6 cytokine family receptors was reduced. Immunohistology suggested expression of OSM, gp130, leukaemia inhibitory factor receptor (LIFr) and IL-11r in the hair follicle root sheaths and dermal papilla, while IL-11, IL-6r and OSMr were expressed in root sheaths alone. IL-6 was expressed in the dermal papilla while cardiotrophin-1 (CT-1) and LIF were not observed. OSM and to a lesser extent CT-1 exhibited a dose-dependent growth inhibition capacity on human hair follicles in vitro. OSM and CT-1 incubated with agarose beads and injected subcutaneously at 1 mug per mouse into telogen skin of 65-day-old mice revealed no capacity to induce anagen hair growth. In contrast, injection of 65-day-old mice in which anagen had been induced by hair plucking revealed a moderate hair growth inhibitory capacity for OSM, but no significant effect for CT-1. The data identify OSM as a modulator of hair follicle growth and suggest other family members may also have some degree of hair growth inhibitory effect. In principle, increased expression of some IL-6 cytokine family members in cutaneous inflammation might contribute to the promotion of hair loss.

Substance P as an Immunomodulatory Neuropeptide in a Mouse Model for Autoimmune Hair Loss (Alopecia Areata)

Alopecia areata (AA) is an autoimmune disorder of the hair follicle characterized by inflammatory cell infiltrates around actively growing (anagen) hair follicles. Substance P (SP) plays a critical role in the cutaneous neuroimmune network and influences immune cell functions through the neurokinin-1 receptor (NK-1R). To better understand the role of SP as an immunomodulatory neuropeptide in AA, we studied its expression and effects on immune cells in a C3H/HeJ mouse model for AA. During early stages of AA development, the number of SP-immunoreactive nerve fibers in skin is increased, compared to non-affected mice. However, during advanced stages of AA, the number of SP-immunoreactive nerves and SP protein levels in skin are decreased, whereas the expression of the SP-degrading enzyme neutral endopeptidase (NEP) is increased, compared to control skin. In AA, NK-1R is expressed on CD8+ lymphocytes and macrophages accumulating around affected hair follicles. Additional SP supply to the skin of AA-affected mice leads to a significant increase of mast cell degranulation and to accelerated hair follicle regression (catagen), accompanied by an increase of CD8+ cells-expressing granzyme B. These data suggest that SP, NEP, and NK-1R serve as important regulators in the molecular signaling network modulating inflammatory response in autoimmune hair loss.

Changes in distribution pattern of CD8 lymphocytes in the scalp in alopecia areata during treatment with diphencyprone

For many years, the role of T lymphocytes was hypothesized as being a major factor responsible for hair loss in alopecia areata (a.a.). While numerous lymphocytic populations were found around hair bulbs, changes in their distribution patterns in the skin during the course and recovery of the disease remain unknown. In the present study, distribution of CD8 lymphocytes in biopsies obtained from a.a. patients was measured before and during treatment using diphencyprone (DCP). Results show about a 600% increase in the number of CD8 lymphocytes under the epithelium and about a 250% increase around hair bulbs and other epidermal appendages during the study. These results were more significant in a group, which had good clinical response to the treatment. No change in the quantity of CD8 lymphocytes was observed around the blood vessels. Since CD8 lymphocytes are considered to be directly involved in the hair destruction process in a.a., their increased number around hair bulbs followed by hair regrowth may suggest that during DCP treatment they regain normal reactivity to hair antigens.

Interferon-gamma-deficient mice are resistant to the development of alopecia areata

BACKGROUND

Alopecia areata (AA) is a T-cell mediated putative autoimmune disease of hair follicles, which can be transferred by CD4(+) T cells. However, whether T-helper (Th) 1 or Th2 cytokines are predominant has not yet been defined.

OBJECTIVES

To elucidate the importance of Th1 cells in the pathogenesis of AA we investigated the functional role of interferon (IFN)-gamma in the experimental induction of AA.

METHODS

AA was experimentally induced by grafting full-thickness skin from AA-affected C3H/HeJ mice on to C3H/HeJ mice with a targeted deletion of the Th1 cytokine IFN-gamma gene (IFNgamma(-/-)) and on to wild-type mice (IFNgamma(+/+)).

RESULTS

While 90% of wild-type mice developed AA, none of the IFNgamma(-/-) mice exhibited hair loss. Immunohistochemistry of skin sections revealed a dense perifollicular and intrafollicular infiltrate of CD4(+) and CD8(+) T cells in controls, while in IFNgamma(-/-) mice skin-infiltrating CD8(+) T cells were absent and the number of CD4(+) cells was significantly reduced. Aberrant expression of major histocompatibility complex class I and II molecules in the putative immune-privileged infrainfundibular site of the hair follicle was found to be weaker in AA-resistant IFNgamma(-/-) mice than in control mice with AA. Flow cytometry revealed that leucocytes of IFNgamma(-/-) mice did not respond to the transfer of AA-affected skin. As distinct from IFNgamma(+/+) mice, neither T-cell activation markers nor Th1 cytokines were upregulated in draining lymph node cells or skin-infiltrating leucocytes of AA-resistant IFNgamma(-/-) mice. However, there was no evidence for a shift towards a Th2 cytokine profile, nor for upregulation of regulatory T cells in IFNgamma(-/-) mice.

CONCLUSIONS

IFNgamma(-/-) mice fail to activate Th1 cells in response to the transplanted (auto)antigens, which suggests an essential requirement for IFN-gamma-mediated Th1 activation in the induction of AA.

A Chronic Contact Eczema Impedes Migration of Antigen-Presenting Cells in Alopecia Areata

Long-lasting allergen treatment is the most efficient therapy in alopecia areata (AA). The underlying mechanism is unknown. We here asked whether treatment with a contact sensitizer influences leukocyte migration such that dendritic cell (DC) migration or the recruitment of activated T-cells towards the skin become hampered. Allergen treatment of AA mice was not accompanied by a decrease in skin-infiltrating leukocytes or draining lymph node cells (LNC). However, the distribution of leukocyte subsets was changed with a dominance of monocytes in the skin and a reduced percentage of DCs in draining nodes. Chemokine and chemokine receptor expression in skin and draining nodes was strikingly increased and LNC from untreated and allergen-treated AA mice showed high migratory activity in vitro and readily homed in draining nodes and skin after intravenous injection. However, FITC labelling of the skin and subcutaneous transfer of dye-labelled DC revealed that allergen treatment created a chemokine milieu severely hampering DC migration from the skin towards the draining node. An allergic eczema-induced reduction in DC migration and antigen transfer could well contribute to insufficient T-cell activation and the recovery of hair follicle in AA and possibly be of relevance for other skin-related autoimmune diseases.

Alopecia Areata: A tissue specific autoimmune disease of the hair follicle

The goal of this review is to introduce the immunologic community to alopecia areata as a model system for the study of tissue directed autoimmune disease. Alopecia areata is marked by autoimmune assault on the hair follicle resulting in hair loss. It is linked to HLA-DQ3 and evidence suggests it is mediated by T-lymphocytes with a TH1 cytokine profile. Hair follicles are an immune protected site with deficient MHC expression. Evidence is presented suggesting that alopecia areata results from loss of immune privilege with presentation of autoantigens. Alopecia areata is one of the most common human autoimmune conditions, with a lifetime risk of approximately 1.7%. Study of alopecia areata in humans is facilitated by the accessibility of scalp for biopsy. It is possible to transfer the condition with lesional human lymphocytes in a human scalp graft/SCID mouse model. There are also spontaneous animal models which share the features of the human condition. For these reasons, alopecia areata is a powerful model for study of the induction and pathogenesis of tissue directed autoimmune disease.

[Alopecia areata in animal models--new insights into pathogenesis and treatment of a T cell-mediated autoimmune disorder]

Alopecia areata is a common disease, but for ethical reasons it seems difficult to perform large-scale studies to elucidate the pathogenesis and to develop new therapeutic approaches in man. It is therefore helpful to develop appropriate animal models. The Dundee experimental bald rat (DEBR) and the C3H/HeJ mouse are well-established animal models for alopecia areata and can be used for the study of genetic aspects, pathogenesis and therapy of the disease. In C3H/HeJ mice alopecia areata can be experimentally induced by grafting lesional skin from an affected mouse to a histocompatible recipient which offers the possibility to study the influence of various factors on the development of the disease. Studies on the C3H/HeJ mouse and the DEBR have corroborated the concept that alopecia areata is a T-cell mediated autoimmune disease and various steps and aspects of the pathogenesis have been elucidated. Based on this knowledge new therapeutic options may be developed such as inhibition of lymphocyte-homing by an anti-CD44v10 antibody, or inhibition of costimulation by monoclonal antibodies. Therapeutic studies in the C3H/HeJ mouse and the DEBR suggest that alopecia areata can be treated by topical tacrolimus but treatment in humans may only be successful after development of an improved vehicle that facilitates penetration of tacrolimus down to the hair bulb. Current investigations in mice are designed to elucidate the mechanisms how contact sensitizers act in the treatment of alopecia areata, and this will hopefully lead to the development of more specific approaches based on the beneficial effect of contact sensitizers.

Alopecia areata presenting in 2 kidney-pancreas transplant recipients taking cyclosporine

Alopecia areata (AA) is an autoimmune disease of uncertain pathogenesis, typically treated with immunomodulators. We report the paradoxical development of AA in two kidney-pancreas transplant recipients receiving immunosuppressive therapy, which included cyclosporine. Review of the literature revealed only 7 other cases of AA occurring in solid organ transplant recipients; all occurred during long-term cyclosporine therapy. The development of AA in this population highlights the complexity of this immunologic disease.

Mouse alopecia areata models: an array of data on mechanisms and genetics

Laboratory mice have become the premier animal model for most human and domestic animal diseases, and they have long been the model of choice for studying mammalian genetics, especially since the advent of genetic engineering. Many remarkable discoveries have been made through intense study of these wonderful small mammals, and undoubtably many more will be made. It is no surprise that one mouse model for alopecia areata (AA) has been found possibly many more will be, some of which exhibit rare phenotypes found in subpopulations of humans with the disease, such as nail deformities, thyroid disease, inflammatory bowel disease, and autoimmune polyendocrine syndrome type 1. Intense investigation by many groups into the first model, the adult onset form of AA (using the C3H/HeJ inbred strain), found similarities as well as differences with commonly held ideas concerning human AA. Regardless of some of the controversies, much insight has been gained from studying these and other rodent and domestic animal models which has opened up new ideas and discussions of AA and its treatment.

Old wine in new bottles: reviving old therapies for alopecia areata using rodent models

Alopecia areata is regarded as a tissue-restricted autoimmune disease of hair follicles in which follicular activity is arrested because of the continued activity of lymphocytic infiltrates. Actual loss of hair follicles does not occur, even in hairless lesions. A variety of immunomodulating therapies, including contact sensitizers and immunomodulators, are part of the usual armamentarium for this disorder. None of these treatments have been consistent in their efficacy, and many have untoward side effects. Nevertheless, their uses in valid animal models provide a tool to dissect out molecular mechanisms of therapeutic effects. For several decades, both mechlorethamine (for the treatment of cutaneous T cell lymphoma) and anthralin (for the treatment of psoriasis) have been used successfully. When these therapies were tested in rat and mouse alopecia areata models, we found anthralin and mechlorethamine to be the most effective topical modalities, respectively. The underlying cellular mechanisms may act through targeting infiltrative lymphocytes, and the molecular mechanisms may involve specific cytokine expression changes. These visible, accessible, and unilaterally treated animal model systems are ideal for studying novel alopecia areata therapies, particularly in terms of their in vivo molecular mechanisms of action.

Chronic delayed-type hypersensitivity reaction as a means to treat alopecia areata

The acute phase of alopecia areata (AA) is characterized by an increase in CD44v3+ and CD44v10+ skin-infiltrating leucocytes (SkIL). Induction of a contact eczema, one of the therapeutic options in AA, can be mitigated strongly by a blockade of CD44v10. The observation that induction of a delayed type hypersensitivity (DTH) reaction abrogates an autoimmune reaction, where both responses apparently use similar effector mechanisms, is surprising and prompted us to search for the underlying mechanisms. AA-affected C3H/HeJ mice were treated with the contact sensitizer SADBE (squaric acid dibutylester) and leucocyte subpopulations and their activation state was evaluated in SkIL and draining lymph nodes. AA-affected mice exhibited an increased number of SkIL with a predominance of T lymphocytes. After treatment with the contact sensitizer SADBE recovery of SkIL was reduced and monocytes predominated. However, a significantly increased number of leucocytes was recovered from draining lymph nodes. Draining lymph node cells from untreated and treated AA mice exhibited all signs of recent activation with high-level expression of co-stimulatory and accessory molecules and an increased percentage of CD44v3+ and CD44v10+ leucocytes. In contrast, SkIL of SADBE-treated AA mice contained relatively few activated T cells and reduced numbers of CD44v3+ and CD44v10+ cells. Thus, the activation state and the distribution of leucocyte subsets in SADBE-treated AA mice are consistent with a blockade of leucocyte extravasation. Accordingly, the therapeutic effect of long-term SADBE treatment may rely on impaired leucocyte traffic.

Restoration of hair growth with topical diphencyprone in mouse and rat models of alopecia areata

BACKGROUND

The contact sensitizer, diphencyprone (DPCP), is one of the most effective therapies for the more severe forms of alopecia areata (AA).

OBJECTIVE

The purpose of this study was to determine the efficacy of topical DPCP on the 2 available rodent models for AA, and to determine the underlying therapeutic mechanisms.

METHODS

AA-affected mice and rats were treated unilaterally with topical DPCP on the ventral and dorsal surface, respectively. The opposite sides were treated with vehicle alone. Skin biopsy specimens were collected from both sides for histologic analysis.

RESULTS

Hair regrowth was observed on the treated sides in the majority of the animals of both species. Immunohistochemical analyses revealed reduction of intrafollicular CD8(+) lymphocyte infiltrates after successful treatment in mice.

CONCLUSION

The AA-like hair disorder of these 2 rodent models can be used as a tool for furthering our understanding of human AA and the therapeutic actions of DPCP.

Restoration of hair growth in mice with an alopecia areata-like disease using topical anthralin

Anthralin is a widely used topical anti-psoriatic drug that may have an immunomodulating effect on alopecia areata (AA) as it does in psoriasis. The aims of the present study were to investigate the effects of anthralin on hair growth in balding C3H/HeJ mice affected by an AA-like disease and to study the underlying mechanisms. Affected C3H/HeJ mice were treated daily for 10 weeks on half of the dorsal skin with 0.2% anthralin and the contra-lateral side was treated with the vehicle ointment. The percentage of surface hair coverage and hair density was graded weekly for both sides and hair growth indices were calculated using these two variables. Hair regrowth was observed in 9/14 mice on the treated sides. Four mice displayed near complete replacement of normal density and length hairs. All the vehicle-treated sides showed either no change or continued hair loss. An RNase protection assay (RPA) showed that expression of tumor necrosis factor-alpha (TNF-alpha) and -beta were inhibited by anthralin upon successful treatment. It appears that anthralin may be an effective therapy for C3H/HeJ mice with AA and certain cytokines may be involved in the therapeutic effects of anthralin on restoring hair regrowth in AA-affected C3H/HeJ mice.

Autoimmunity: Alopecia Areata

Strong direct and indirect evidence supports an autoimmune etiology for alopecia areata. T lymphocytes that have been shown to be oligoclonal and autoreactive are predominantly present in the peribulbar inflammatory infiltrate. Alopecia areata frequently occurs in association with other autoimmune diseases, such as thyroiditis and vitiligo, and autoantibodies to follicular components have been detected. Finally, the use of immune modulating drugs, including corticosteroids and contact sensitizers such as dyphencyprone, can be beneficial in the management of this disease. Recent studies have demonstrated that alopecia areata scalp skin grafted onto nude mice with severe combined immunodeficiency grow hair and that infiltrating lymphocytes in the graft are lost. It is now also possible to induce alopecia areata in human scalp explants on these mice by injecting T lymphocytes with scalp homogenate. Neuropeptides produced by cutaneous nerves are known to modify immune reactivity and, in all likelihood, affect the alopecia areata process. Future studies may show that modulation of neuropeptide expression is associated with hair regrowth. Likewise, testing the efficacy of the newly developed immunomodulatory agents in patients with alopecia areata may lead to the introduction of novel therapies for this immune-mediated disease of the hair follicle.

Alopecia Areata: Autoimmunity—The Evidence Is Compelling

There is strong evidence indicating that alopecia areata is a tissue-specific, autoimmune disease. Hair loss is associated with a perifollicular lymphocytic infiltrate made up primarily of CD4+ cells, along with a CD8+ intrafollicular infiltrate. Evidence of immune activation includes expression of HLA-DR; HLA-A,B,C; and ICAM-1 on the follicular epithelium. It is likely that the follicular expression of HLA-DR and ICAM-1 is induced by interferon-gamma produced by T cells. Antibodies to follicular epithelium are often present, but their significance is not known. Lesional scalp from alopecia areata patients grafted onto nude mice regrows hair coincident with a loss of infiltrating lymphocytes from the graft. Hair loss can be transferred to human scalp explants on SCID mice by injection of lesional T cells. It is necessary to activate the T cells by culture with follicular autoantigens. Melanocyte-associated antigens are also capable of activating T cells to induce hair loss, suggesting that they are capable of functioning as autoantigens for alopecia areata. Parallel evidence in rodent models of spontaneous alopecia areata also strongly supports a role for T cells in the pathogenesis of this condition.

The pathogenesis of alopecia areata in rodent models

Rodent models of human disease provide an important tool in the investigation of genetic and environmental activation factors, disease pathogenesis, and the development of new and improved treatments. Up to 20% of aged C3H/HeJ mice and 70% of Dundee Experimental Bald Rats (DEBR) develop alopecia areata (AA), a nonscarring, inflammatory hair loss disease with a suspected autoimmune pathogenesis. These rodent models are currently employed in determining the genetic basis of AA, understanding the mechanisms of disease initiation and progression, and defining potential endogenous and environmental influences. Induction of AA by skin graft transfer between affected and unaffected mice has been employed to examine skin and immune system changes during AA pathogenesis. Manipulation of inflammatory cells in vivo indicates AA is primarily a cell mediated disease with auto-antibody production as a secondary event. Whether the AA activating factors are exogenous or endogenous antigens, or involve normal or aberrant epitope expression remains to be elucidated. However, current research suggests a self contained disease cycle involving four key events: (1) Failure of the putative anagen stage hair follicle immune privilege and exposure of hair follicle located AA inciting epitopes to the immune system; (2) Antigen presentation, costimulation, and activation of responsive lymphocytes by antigen presenting cells; (3) Activated inflammatory cell migration to, and infiltration of, hair follicles; (4) The subsequent disruptive actions of the inflammatory cell infiltrate on the hair follicles. Each of these events is vulnerable to therapeutic intervention, and rodent models will be fundamentally involved in developing new treatments for AA.

Fas-deficient C3.MRL-Tnfrsf6(lpr) mice and Fas ligand-deficient C3H/HeJ-Tnfsf6(gld) mice are relatively resistant to the induction of alopecia areata by grafting of alopecia areata-affected skin from C3H/HeJ mice

Alopecia areata is suspected to be a T cell-mediated autoimmune disease of the hair follicle, where Fas is expressed on hair follicles and Fas ligand on perifollicular infiltrates. To elucidate whether the Fas/Fas ligand pathway is of pathogenetic significance in alopecia areata, we investigated whether alopecia areata can be induced in Fas-deficient and Fas ligand-deficient mice and whether alopecia areata develops in Fas-deficient and Fas ligand-deficient skin. Therefore, we induced alopecia areata by grafting alopecia areata-affected C3H/HeJ mouse skin on to C3H/HeJ mice (control), on to Fas ligand-deficient C3H/HeJ-Tnfsf6(gld) mice or Fas-deficient C3.MRL-Tnfrsf6(lpr) mice. All control mice developed alopecia areata, whereas no Fas-deficient mice showed hair loss and two of seven Fas ligand-deficient mice developed only transitory, limited alopecia areata. Moreover, skin from C3H/HeJ mice (control), C3H/HeJ-Tnfsf6(gld) mice, and C3.MRL-Tnfrsf6(lpr) mice was grafted on to C3H/HeJ mice with extensive alopecia areata. Skin grafts from control mice developed hair loss, whereas Fas-deficient and Fas ligand-deficient skin grafts were spared from alopecia areata. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling and immunofluorescence studies revealed an increased number of apoptotic cells and expression of Fas on hair follicles as well as expression of Fas ligand on cells of the perifollicular infiltrate in C3H/HeJ mice with alopecia areata, whereas in Fas-deficient and Fas ligand-deficient mice apoptotic cells were virtually absent in hair follicles. The results suggest that the Fas/Fas ligand pathway plays an important pathogenetic role in alopecia areata.

Topical mechlorethamine restores autoimmune-arrested follicular activity in mice with an alopecia areata-like disease by targeting infiltrated lymphocytes

Alopecia areata is an autoimmune disease targeted at hair follicles with infiltrated T lymphocytes probably playing an important role in the pathogenesis. It was reported in 1985 that mechlorethamine was effective on alopecia areata patients. This has never been confirmed since. The aims of the study were to investigate the effects of mechlorethamine on balding C3H/HeJ mice affected with an alopecia-areata-like disease and to study the underlying mechanisms. Mice were treated on half of the dorsal skin with mechlorethamine and the contralateral side was treated with the vehicle ointment. After 10 wk of mechlorethamine therapy, a full pelage of hair covered the treated side in all the mice and was maintained during the study, whereas the vehicle-treated sides showed either no change or continued hair loss. Immunohistochemistry revealed that infiltrated CD4+ and CD8+ lymphocytes were eliminated from the treated side. In vitro cell viability assay showed that lymphocytes were much more sensitive to the cytotoxic effects of mechlorethamine than skin and hair follicular cells. RNase protection assay and real-time reverse transcription polymerase chain reaction showed that tumor necrosis factor alpha/beta, interleukin-12, and interferon-gamma were inhibited by mechlorethamine upon successful treatment. Our findings support that mechlorethamine restores follicular activity by selectively targeting infiltrated lymphocytes in vivo in alopecia-areata-affected mice.

Dietary soy oil content and soy-derived phytoestrogen genistein increase resistance to alopecia areata onset in C3H/HeJ mice

Alopecia areata (AA) is a complex, multi-factorial disease where genes and the environment may affect susceptibility and severity. Diet is an environmental factor with the potential to influence disease susceptibility. We considered dietary soy (soya) oil content and the soy-derived phytoestrogen genistein as potential modifying agents for C3H/HeJ mouse AA. Normal haired C3H/HeJ mice were grafted with skin from spontaneous AA affected mice, a method previously shown to induce AA. Grafted mice were given one of three diets containing 1%, 5% or 20% soy oil and observed for AA development. In a separate study, mice on a 1% soy oil diet were injected with 1 mg of genistein three times per week for 10 weeks or received the vehicle as a control. Of mice on 1%, 5%, and 20% soy oil diets, 43 of 50 mice (86%), 11 of 28 mice (39%), and 2 of 11 mice (18%) developed AA, respectively. Four of 10 mice injected with genistein and 9 of 10 controls developed AA. Mice with AA had hair follicle inflammation consistent with observations for spontaneous mouse AA, but no significant association was observed between the extent of hair loss and diet or genistein injection. Mice that failed to develop AA typically experience white hair regrowth from their skin grafts associated with a moderate macrophage and dendritic cell infiltration. Soy oil and derivatives have previously been reported to modify inflammatory conditions. Hypothetically, soy oil compounds may act on C3H/HeJ mice through modulating estrogen-dependent mechanisms and/or inflammatory activity to modify AA susceptibility.

Resistance to alopecia areata in C3H/HeJ mice is associated with increased expression of regulatory cytokines and a failure to recruit CD4+ and CD8+ cells

Grafting alopecia areata affected C3H/HeJ mouse skin to littermates induces alopecia areata, but high dietary soy oil reduces alopecia areata susceptibility. Alopecia areata affected and resistant mice were characterized to evaluate possible mechanisms involved in alopecia areata resistance. Of 44 mice that received alopecia areata affected skin grafts but failed to develop alopecia areata, only two of 22 receiving further alopecia areata affected skin grafts developed alopecia areata, whereas 39 of 44 controls developed alopecia areata. Alopecia areata affected skin contained increased numbers of CD4+ and CD8+ cells, increases in pro inflammatory T helper 1 and T helper 2 type cytokines, and upregulation of CD28, CD40L, and their ligands. In draining lymph nodes, a relatively high number of antigen-presenting cells was recovered, whereas several CD44v variants were downregulated. In contrast, alopecia areata resistant mouse skin did not display increased numbers of CD4+ and CD8+ cells, whereas counter-regulatory cytokines interleukins 4 and 10 were upregulated. High expression of CD28, CD80, CD86, CD40, CTLA4, CD44v variants, and FasL occurred in alopecia areata resistant mouse spleens. In vitro, lymph node cells of susceptible and resistant mice responded equally to a mitogenic stimulus, but only lymph node cells from alopecia areata affected mice displayed an increased response with T cell receptor stimulation via anti-CD3 cross-linking. These results suggest alopecia areata is a cell-mediated autoimmune disease, but alopecia areata affected skin graft hosts may resist alopecia areata onset through active counter-regulatory mechanisms. Because alopecia areata resistant mice showed unimpaired responsiveness and a transient inflammatory response towards the graft, it is suggested that alopecia areata develops as a consequence of an inappropriate immune response regulation.

Seventeen cases of alopecia areata: combination of SADBE topical immunotherapy with other therapies

Topical immunotherapy is effective for severe alopecia areata. However, there are patients with alopecia areata refractory to topical immunotherapy alone. We tried SADBE (squaric acid dibutylester) topical immunotherapy combined with topical dry ice cryotherapy, carpronium chloride (a parasympathetic nerve stimulant) and/or oral cepharanthin (a biscoclaur alkaloid) in alopecia areata refractory to topical SADBE. Seventeen patients with alopecia areata (3 multiple, 3 ophiasis, 5 totalis and 6 universalis) were treated with SADBE in our department in 1999 to 2001. In 3 cases (2 multiple and 1 universalis) out of the 17 cases, cosmetically acceptable regrowth of hair was observed in several months with topical SADBE alone. In the other 14 cases, the SADBE therapy alone for several months (mean: 6.9 months) resulted in no or poor regrowth of hair. However, with subsequent combination therapy of topical SADBE for several months (mean: 7.6 months), satisfactory regrowth of hair was observed in 6 of the 14 cases. Our cases indicate that combination therapy of topical SADBE with other therapies can be a choice for alopecia areata which is refractory to topical SADBE therapy alone.

Gene array profiling and immunomodulation studies define a cell-mediated immune response underlying the pathogenesis of alopecia areata in a mouse model and humans

Alopecia areata is a suspected autoimmune hair loss disease. In a rodent model, alopecia areata can be induced in normal haired C3H/HeJ mice by transfer of skin grafts from mice with spontaneous alopecia areata. At weeks 2, 4, 6, and 10 after surgery, grafted mice were euthanized, skin collected and processed for histology, and RNA extracted. Age-matched sham-grafted mice, and mice with and without spontaneous alopecia areata, were similarly processed. For comparison, skin biopsies from alopecia areata and androgenetic alopecia affected humans were also collected. Skin mRNA processed to cDNA was analyzed using Affymetrix mouse 11K and human 6800 gene chip(R) array technology. Microarray results indicated 42 known genes upregulated or downregulated during onset of mouse alopecia areata consistent with an inflammatory cell-mediated disease pathogenesis involving antigen presentation, costimulation, and a T helper 1 lymphocyte response. In contrast, 114 genes, many regulating immunoglobulin response, were altered late in disease development. In alopecia areata affected humans, 95 genes were significantly modulated. As confirmation of microarray analysis results, lymph node and spleen cells from alopecia areata affected mice injected into normal haired littermates transferred the alopecia areata phenotype. Alopecia areata onset could be inhibited in skin-grafted mice by modulation with B7.1- and B7.2-specific monoclonal antibodies. In addition, depletion of CD4+ CD8+ expressing cells in chronic alopecia areata affected mice using monoclonal antibodies permitted hair regrowth. The results consistently demonstrated the importance of an immune cell-mediated disease mechanism in alopecia areata pathogenesis and suggested targeting antigen-presenting cells and reactive lymphocytes may be effective in alopecia areata treatment.

Alopecia areata - animal models

Several rodent models with spontaneous and induced alopecia areata (AA), a nonscarring inflammatory hair loss disease with suspected autoimmune elements, have been identified. Of these, the C3H/HeJ mouse and DEBR rat have been most extensively used in examining AA development. Flow cytometry and micro array characterization, manipulation of inflammatory cells by in vivo cell depletion or cell receptor blockade, lymph node cell transfer between affected and unaffected rodents, and the recent use of transgenic knockout mice have given important insights into the development of AA. From our current understanding of rodent models, the development of AA relies upon a general genetic susceptibility where major susceptibility genes may be supplemented by minor disease severity modifying genes. However, the actual onset of AA, its duration, extent, and persistence in individual rodents may be modified by epigenetic factors. Rodent AA seems to be fundamentally, but not exclusively, Th1 cell mediated. Onset of disease may be dependent on several factors including the break down of the putative anagen stage hair follicle immune privilege, appropriate antigen presentation with costimulation of lymphocytes, presence of autoreactive lymphocytes, and a deficiency of functional immune system regulatory cells. Rodents have already been used in examining a variety of current AA treatments and developing new therapies with some success. With a greater understanding of AA disease mechanisms through rodent model research, improved and more specific treatment interventions may be defined.

Melanocyte and gonad activity as potential severity modifying factors in C3H/HeJ mouse alopecia areata

Circumstantial evidence has previously suggested gonad derived steroid hormones and melanogenesis related antigens may modify human alopecia areata (AA). AA-like hair loss can be induced in C3H/HeJ mice after skin allografts from spontaneous AA-affected mice. This inducible model was used to evaluate hormones and hair follicle melanocyte presence as disease-severity modifiers. Ten females and 9 males were gonadectomized and received AA-affected allografts. All gonadectomized mice had 2-4 weeks delay in AA onset relative to non-gonadectomized controls. Two females and 4 males failed to develop any AA by 25 weeks after grafting. The experiment was repeated with gonadectomized female and male mice plus non-gonadectomized mice subcutaneously implanted with silastic capsules containing 80 microg 17beta estradiol or 10 mg 5alpha dihydrotestosterone, respectively. Five of 11 ovariectomized and 9 of 11 non-ovariectomized, estradiol supplemented females developed AA with extremely rapid progression. Three of 8 castrated, but none of 11 non-castrated, dihydrotestosterone-supplemented males expressed AA. In a separate study, 14 mice were freeze-branded, producing white hair on the dorsal lumbar region, and later received full-thickness allografts. Thirteen mice developed patchy pigmented and non-pigmented hair loss. One mouse developed diffuse, pigmented hair loss, but with white hair survival persisting 25 weeks after grafting. The results suggest that gonadal steroid hormones can modulate C3H/HeJ mouse AA where estradiol promoted rapid progression of AA while dihydrotestosterone increased resistance to AA onset. In general, both pigmented and non-pigmented C3H/HeJ mouse hair is susceptible to AA. Murine AA susceptibility and severity clearly involves an interplay between genetic and epigenetic factors.

Treatment with an anti-CD44v10-specific antibody inhibits the onset of alopecia areata in C3H/HeJ mice

A murine CD44v10-neutralizing antibody has been reported to impair delayed-type hypersensitivity reactions. Because alopecia areata is characterized by a delayed-type hypersensitivity-like T cell mediated immune response, we addressed the question whether an anti-CD44v10-antibody influences the onset of alopecia areata. Therefore, we used the C3H/HeJ mouse model with the induction of alopecia areata in unaffected mice by the grafting of lesional alopecia areata mouse skin. Six grafted mice were injected (intraperitoneally) with anti-CD44v10, six grafted mice with anti-CD44standard, and six with phosphate-buffered saline only. After 11 wk phosphate-buffered saline injected animals on average had developed alopecia areata on 36.8% of their body. The onset of hair loss was slightly delayed and its extent reduced to 17.2% of their body in anti-CD44standard-treated mice. By contrast, five of six anti-CD44v10-treated mice did not show any hair loss and one mouse developed alopecia areata on only 1% of the body. Immunohistochemical examination revealed a marked reduction of perifollicular CD8+ lymphocytes and, to a lesser degree, CD4+ cells as well as a decreased expression of major histocompatibility complex class I on hair follicle epithelium in anti-CD44v10-treated mice as compared with phosphate-buffered saline or anti-CD44 standard-treated mice. Our data show that anti-CD44v10 is able to inhibit the onset of alopecia areata in C3H/HeJ mice. This might be accomplished by an anti-CD44v10-triggered impairment of immune cell homing (e.g., CD8+ T cells), resulting in a decrease of their number in target tissues.