HLA-DR expression by hair follicle keratinocytes in alopecia areata: evidence that it is secondary to the lymphoid infiltration

Causal role of immune cells in alopecia areata: A two-sample Mendelian randomization study

BACKGROUND

Previous research has highlighted an association between alopecia areata (AA) and the collapse of hair follicle immune privilege, however, the causal linkage to specific immune cell traits remains to be elucidated. This study aimed to investigate the causal influence of immune cell traits on AA utilizing a two-sample Mendelian randomization (MR) approach.

METHODS

Leveraging GWAS summary statistics of 731 immunological traits (n = 3757) and AA data (n = 211,428), MR analyses were conducted employing inverse-variance weighted (IVW), weighted median, and MR-Egger regression methodologies. Sensitivity analyses were undertaken using Cochran's Q test, MR-Egger intercept test, and MR-PRESSO analysis. A reverse MR analysis was performed for immune cell traits identified in the initial MR analysis.

RESULTS

Our study unveiled multiple immune traits associated with AA. Protective associations were observed for CD62L- CD86+ myeloid dendritic cells (DCs), TD CD4+%CD4+ T cells, and others, with ORs ranging from 0.63 to 0.78. Conversely, traits like CD62L on CD62L+ plasmacytoid DCs, HLA-DR on CD14- CD16+ monocytes, HLA-DR on monocytes, and others, were determined to augment the risk of AA, with ORs ranging from 1.13 to 1.46. Reverse MR analysis signified a reduction in BAFF-R on IgD-CD24-B cells post-AA onset (OR: 0.97, 95% CI: 0.95-1.00), with no identified heterogeneity or horizontal pleiotropy among the instrumental variables (IVs).

CONCLUSIONS

Our findings suggests that CD62L on certain subpopulations of DCs and HLA-DR on monocytes may epitomize risk factors for AA, offering potential therapeutic targets for alleviating AA.

Epigallocatechin-3 Gallate Inhibits STAT-1/JAK2/IRF-1/HLA-DR/HLA-B and Reduces CD8 MKG2D Lymphocytes of Alopecia Areata Patients

BACKGROUND

Alopecia areata (AA) is associated with Interferon- γ (IFN-γ) mediated T-lymphocyte dysfunction and increased circulating Interleukine-17 (IL-17) levels. Epigallocatechin-3-gallate (EGCG) specifically inhibits IFN-γ pathways and unlike Janus Kinase 1 and 2 (JAK1/JAK2) inhibitors (tofacitinib, ruxolitinib), EGCG is safer, more cost-effective, and is a topically active agent. Our objective is to test the mode of action of EGCG in vitro and ex vivo using HaCat, Jurkat cell lines, and peripheral blood mononuclear cells (PBMCs) of AA patients and healthy controls (HCs), respectively.

METHODS

distribution of T helper cells (Th1, Th17), and cytotoxic cells (CD8) in PBMCs isolated from 30 AA patients and 30 HCs was investigated by flowcytomterty. In vitro treatment of HaCat and Jurkat cells with 40 μm EGCG for 48 h was performed to measure the level of phosphorylation of signal transducer and activator of transcription protein STAT1, and replicated in ex vivo model using PBMCs of AA patients.

RESULTS

Interestingly, 40 μm EGCG is capable of completely inhibiting phosphorylation of STAT1 after 48 h in HaCat and Jurkat cells and ex vivo in PBMCs of AA patients. Based on QPCR data, the action of EGCG on p-STAT1 seems to be mediated via downregulation of the expression of JAK2 but not JAK1 leading to the inhibition of human leukocyte antigens (HLA-DR and HLA-B) expression probably via IRF-1. On the other hand, AA patients have significantly increased levels of Th1, Th17, and CD8 cells and the production of IFN-γ and IL-17 by PBMCs in AA patients was significantly higher compared to HC; p = 0.008 and p = 0.006, respectively. Total numbers of CD8+ cells were not significantly different between treated and untreated samples. However, CD8+ cells with positive Natural killer group 2 member D (NKG2D) transmembrane receptor (CD8+ NKG2D+ subset) was significantly reduced when PBMCs were treated with 20 μm EGCG for 48 h.

CONCLUSION

These results suggest that EGCG has a synergistic action that inhibits expression of HLA-DR and HLA-B molecules via the IFN-γ pathway to maintain immune privilege in HF; also it reduces CD8+ NKG2D+ subset.

Alopecia areata: a review of disease pathogenesis

BACKGROUND

Alopecia areata is a disorder that results in nonscarring hair loss. The psychological impact can be significant, leading to feelings of depression and social isolation. Objectives In this article, we seek to review the pathophysiological mechanisms proposed in recent years in a narrative fashion.

METHODS

We searched MEDLINE and Scopus for articles related to alopecia areata, with a particular emphasis on its pathogenesis.

RESULTS

The main theory of alopecia areata pathogenesis is that it is an autoimmune phenomenon resulting from a disruption in hair follicle immune privilege. What causes this breakdown is an issue of debate. Some believe that a stressed hair follicle environment triggers antigen presentation, while others blame a dysregulation in the central immune system entangling the follicles. Evidence for the latter theory is provided by animal studies, as well investigations around the AIRE gene. Different immune-cell lines including plasmacytoid dendritic cells, natural killer cells and T cells, along with key molecules such as interferon-γ, interleukin-15, MICA and NKG2D, have been identified as contributing to the autoimmune process.

CONCLUSIONS

Alopecia areata remains incurable, although it has been studied for years. Available treatment options at best are beneficial for milder cases, and the rate of relapse is high. Understanding the exact mechanisms of hair loss in alopecia areata is therefore of utmost importance to help identify potential therapeutic targets.

Study of gene expression alteration in male androgenetic alopecia: evidence of predominant molecular signalling pathways

BACKGROUND

Male androgenetic alopecia (AGA) is the most common form of hair loss in men. It is characterized by a distinct pattern of progressive hair loss starting from the frontal area and the vertex of the scalp. Although several genetic risk loci have been identified, relevant genes for AGA remain to be defined.

OBJECTIVES

To identify biomarkers associated with AGA.

METHODS

Molecular biomarkers associated with premature AGA were identified through gene expression analysis using cDNA generated from scalp vertex biopsies of hairless or bald men with premature AGA, and healthy volunteers.

RESULTS

This monocentric study reveals that genes encoding mast cell granule enzymes, inflammatory mediators and immunoglobulin-associated immune mediators were significantly overexpressed in AGA. In contrast, underexpressed genes appear to be associated with the Wnt/β-catenin and bone morphogenic protein/transforming growth factor-β signalling pathways. Although involvement of these pathways in hair follicle regeneration is well described, functional interpretation of the transcriptomic data highlights different events that account for their inhibition. In particular, one of these events depends on the dysregulated expression of proopiomelanocortin, as confirmed by polymerase chain reaction and immunohistochemistry. In addition, lower expression of CYP27B1 in patients with AGA supports the notion that changes in vitamin D metabolism contributes to hair loss.

CONCLUSIONS

This study provides compelling evidence for distinct molecular events contributing to alopecia that may pave the way for new therapeutic approaches.

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.

What causes alopecia areata?

The pathobiology of alopecia areata (AA), one of the most frequent autoimmune diseases and a major unsolved clinical problem, has intrigued dermatologists, hair biologists and immunologists for decades. Simultaneously, both affected patients and the physicians who take care of them are increasingly frustrated that there is still no fully satisfactory treatment. Much of this frustration results from the fact that the pathobiology of AA remains unclear, and no single AA pathogenesis concept can claim to be universally accepted. In fact, some investigators still harbour doubts whether this even is an autoimmune disease, and the relative importance of CD8(+) T cells, CD4(+) T cells and NKGD2(+) NK or NKT cells and the exact role of genetic factors in AA pathogenesis remain bones of contention. Also, is AA one disease, a spectrum of distinct disease entities or only a response pattern of normal hair follicles to immunologically mediated damage? During the past decade, substantial progress has been made in basic AA-related research, in the development of new models for translationally relevant AA research and in the identification of new therapeutic agents and targets for future AA management. This calls for a re-evaluation and public debate of currently prevalent AA pathobiology concepts. The present Controversies feature takes on this challenge, hoping to attract more skin biologists, immunologists and professional autoimmunity experts to this biologically fascinating and clinically important model disease.

Genomewide scan for linkage reveals evidence of several susceptibility loci for alopecia areata

Alopecia areata (AA) is a genetically determined, immune-mediated disorder of the hair follicle that affects 1%-2% of the U.S. population. It is defined by a spectrum of severity that ranges from patchy localized hair loss on the scalp to the complete absence of hair everywhere on the body. In an effort to define the genetic basis of AA, we performed a genomewide search for linkage in 20 families with AA consisting of 102 affected and 118 unaffected individuals from the United States and Israel. Our analysis revealed evidence of at least four susceptibility loci on chromosomes 6, 10, 16 and 18, by use of several different statistical approaches. Fine-mapping analysis with additional families yielded a maximum multipoint LOD score of 3.93 on chromosome 18, a two-point affected sib pair (ASP) LOD score of 3.11 on chromosome 16, several ASP LOD scores >2.00 on chromosome 6q, and a haplotype-based relative risk LOD of 2.00 on chromosome 6p (in the major histocompatibility complex locus). Our findings confirm previous studies of association of the human leukocyte antigen locus with human AA, as well as the C3H-HeJ mouse model for AA. Interestingly, the major loci on chromosomes 16 and 18 coincide with loci for psoriasis reported elsewhere. These results suggest that these regions may harbor gene(s) involved in a number of different skin and hair disorders.

The non-synonymous C1858T substitution in the PTPN22 gene is associated with susceptibility to the severe forms of alopecia areata

Alopecia areata is an acquired hair loss disorder resulting from an immunologically- mediated attack on hair follicles and autoimmunity may play a part in its pathogenesis. The non-synonymous C1858T substitution in the PTPN22 gene, which encodes lymphoid protein tyrosine phosphatase, has been shown to be associated with susceptibility to autoimmune disorders. In this study, the objective was to ascertain whether or not the disease-associated 1858T (W620) allele was associated with alopecia areata. For this, the allelic distribution of the PTPN22 C1858T alleles was determined in 196 English patients with alopecia areata and 507 healthy subjects in a case control study using a restriction fragment length polymorphism-polymerase chain reaction (PCR-RFLP) genotyping method. The results indicated that the frequency of the 1858T allele did not differ significantly between the alopecia areata patient group and the control cohort: of 392 alopecia areata alleles, 41 (10.5%) encoded the W620 variant compared to 86 of 1014 (8.5%) control alleles. However, in patients with severe disease, 25/168 (14.9%) alleles were 1858T and this frequency differed from that in the control group (P = 0.0127; OR, 95% CI = 1.89, 1.17 - 3.05). These results suggest that the non-synonymous C1858T substitution in the PTPN22 gene may have an influence on the severity of alopecia areata and provide further evidence for autoimmunity as an aetiological factor in this disorder.

[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.

Interferon-gamma is a potent inducer of catagen-like changes in cultured human anagen hair follicles

BACKGROUND

Interferon (IFN)-gamma appears to be an important hair cycle modulator in mice. It is unclear whether it has similar hair growth modulatory functions in human hair follicles.

OBJECTIVES

To study whether IFN-gamma can be exploited to modulate the growth, pigmentation and/or cycling of organ-cultured human anagen scalp hair follicles, as an in vitro indicator system for how IFN-gamma affects human hair growth in vivo. This was correlated with the hair follicle expression patterns of IFN-gamma receptors alpha and beta. In addition, we wanted to establish a new, simple tool for the rapid experimental induction of catagen in vitro.

METHODS

Normal human scalp hair follicles in the anagen VI stage of the hair cycle were cultured according to the method of Philpott et al., with or without IFN-gamma (50-1000 IU mL(-1)). Hair shaft elongation and pigmentation changes were measured, complemented by quantitative histomorphometry to assess changes in hair follicle cycling (hair cycle score), proliferation (Ki-67), melanogenesis (Masson-Fontana) and apoptosis (TUNEL). IFN-gamma receptors were also localized by immunofluorescence and EnVision technique. As transforming growth factor (TGF)-beta2 is a recognized key inducer of catagen in human hair follicles, TGF-beta2 expression was investigated by tyramide signal amplification and reverse transcription-polymerase chain reaction in anagen hair follicles treated with vehicle (phosphate-buffered saline) or IFN-gamma.

RESULTS

IFN-gamma rapidly inhibited hair elongation in cultured human anagen hair follicles and induced morphological signs of catagen transformation after only 4 days of culture, i.e. faster than with other reported catagen-inducers (e.g. TGF-beta2). Proliferation was inhibited, apoptosis was increased and follicular melanogenesis was switched off in hair bulb keratinocytes treated in situ with IFN-gamma. Anagen hair follicles displayed strong IFN-gamma receptor alpha-like immunoreactivity, while the immunoreactivity for IFN-gamma receptor beta in the hair matrix was only weak. TGF-beta2 immunoreactivity and mRNA transcript levels were enhanced in hair follicles treated with IFN-gamma.

CONCLUSIONS

These data suggest that IFN-gamma is a potent catagen inducer in normal human scalp hair follicles, which express cognate receptors, and show that IFN-gamma administration offers an excellent tool for experimental catagen induction in organ-cultured human hair follicles. This catagen induction probably occurs at least in part via upregulation of the recognized catagen-stimulatory growth factor TGF-beta2.

Genetic linkage studies in alopecia areata

Alopecia areata affects approximately 4.6 million individuals in the United States alone. It is typified by patchy hair loss on the scalp that can progress to cover the entire scalp (alopecia totalis) and eventually the entire body (alopecia universalis). Despite the high incidence of this condition, its genetic basis is largely unknown. It is now generally accepted, however, that it fits the paradigm of a complex trait, in which a combination of genetic and environmental factors results in the final phenotype. Genetic studies have been limited thus far to association analyses, which suggest that a permissive HLA status may potentiate the development of alopecia areata. A systematic screen for identifying the primary genetic mechanisms underlying this disorder has never before been undertaken, however. Here we discuss our approach to the identification of susceptibility genes for alopecia areata. In particular, we recently initiated a comprehensive genetic analysis by performing a genome-wide scan in a collection of alopecia families with multiple affected family members. There are currently a number of examples of complex diseases of the skin, such as psoriasis and atopic dermatitis, in which genetic studies are being undertaken that substantiate the timeliness of this approach. We anticipate that these studies will lead to the identification of the susceptibility genes and provide a foundation for understanding how they interact with each other and with other variables, such as the immune system and environmental factors.

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.

Transfer of alopecia areata in the human scalp graft/Prkdc(scid) (SCID) mouse system is characterized by a TH1 response

Alopecia areata is an autoimmune condition directed at hair follicles, which results in loss of hair. We have previously demonstrated that it is possible to transfer hair loss, along with the immunohistologic findings of alopecia areata, to human scalp grafts on Prkdc(scid) (SCID) mice by injection of autologous activated lesional T-cells. This study examines the cytokine profile of T-cells and follicular epithelium following transfer of hair loss. Two consistent findings significantly (P < 0.01) associated with hair loss were production of interferon-gamma-inducible protein-10 kDa (IP-10) by follicular epithelium (13/13), and production of INF-gamma by infiltrating T-cells (10/12). Noninjected control grafts regrew hair, and were generally negative for IP-10 (positive 2/9), and INF-gamma (positive 2/9), but expressed of IL-10 on the follicular epithelium (7/9). These data support an INF-gamma TH1 pathogenesis for hair loss in alopecia areata.

Melanocyte-associated T cell epitopes can function as autoantigens for transfer of alopecia areata to human scalp explants on Prkdc(scid) mice

Alopecia areata is a tissue restricted autoimmune condition affecting the hair follicle, resulting in hair loss. The goal of this study was to test the hypothesis that the autoantigen of alopecia areata is melanocyte associated. Potential autoantigens were tested in the human scalp explant/Prkd(scid) CB-17 mouse transfer system. Scalp T cells from lesional (bald) alopecia areata scalp were cultured with antigen-presenting cells, and antigen, along with interleukin-2. The T cells were then injected into autologous lesional scalp grafts on SCID mice, and hair regrowth was measured. Hair follicle homogenate was used as an autoantigen control. T cells cultured with melanoma homogenate induced statistically significant reduction in hair growth (p <0.01 by ANOVA). HLA-A2-restricted melanocyte peptide epitopes were then tested with lesional scalp T cells from HLA-A2-positive alopecia areata patients. Melanocyte-peptide-activated T cells significantly reduced the number of hairs regrowing in two experiments with six patients (p <0.001 by ANOVA). Injected scalp grafts showed histologic and immunochemical changes of alopecia areata. The most consistent peptide autoantigens were the Gp100-derived G9-209 and G9-280 peptides, as well as MART-1 (27-35). Melanocyte peptide epitopes can function as autoantigens for alopecia areata. Multiple peptides were recognized, suggesting epitope spreading.

Hair on a gene string: recent advances in understanding the molecular genetics of hair loss

The hair follicle is finally, after remaining a mystery for many years, beginning to yield some of its molecular secrets. The past decade has seen unprecedented and ever quickening advances in understanding the molecular genetics of the many single gene disorders, which have alopecia as a major feature. This article reviews recent novel clinical and experimental observations, which have shed new light on the basic molecular mechanisms underlying hair morphogenesis, differentiation, keratinization and cycling. We consider recent progress in understanding structural hair defects and complex traits and consider where future developments are likely to occur.

The human hair follicle immune system: cellular composition and immune privilege

The immunology of the hair follicle, its relationship with the 'skin immune system' and its role in hair diseases remain biologically intriguing and clinically important. In this study, we analysed the immunoreactivity patterns of 15 immunodermatological markers to determine the cellular composition and immune privilege of the human hair follicle immune system in anagen VI (growth phase). The most prominent cells located in or around the hair follicle were Langerhans cells, CD4+ or CD8+ T cells, macrophages and mast cells, whereas B cells, natural killer cells and gammadelta T cells were found very rarely. Langerhans cells (CD1a+, major histocompatibility complex, MHC class II+), and T cells (CD4+ or CD8+) were predominantly distributed in the distal hair follicle epithelium, whereas macrophages (CD68+, MHC class II+) and mast cells (Giemsa+) were located in the perifollicular connective tissue sheath. Transmission electron microscopy confirmed low numbers of immune cells in the proximal hair follicle epithelium, and very few macrophages and Langerhans cells were seen in the dermal papilla. Melanophages were observed in the connective tissue sheath and dermal papilla. MHC class I (HLA-A, -B, -C) and beta2-microglobulin immunoreactivity was found on most skin cells, but was substantially reduced on isthmus keratinocytes and virtually absent in the proximal hair follicle epithelium. Apart from the absence of Fas ligand immunoreactivity, the sharply reduced numbers of T cells and Langerhans cells, and the virtual absence of MHC class I expression all suggest that the anagen proximal hair follicle constitutes an area of immune privilege within the hair follicle immune system, whose collapse may be crucial for the pathogenesis of alopecia areata.

Characterization of infiltrating T cells in human scalp explants from alopecia areata to SCID nude mice: possible role of the disappearance of CD8+ T lymphocytes in the process of hair regrowth

T cells may play a role in the pathogenesis of alopecia areata (AA). We attempted to elucidate the linkage between infiltrating T cells and hair regrowth processes by grafting scalp skin from the affected region of patients with AA onto severe combined immune deficiency (SCID) nude mice. When the AA scalp was grafted into the mice, the grafts were accepted, and normal hair regrowth was observed. Before grafting, CD4+ and CD8+ T cells had infiltrated into the peribulb area. After grafting, the telogen hair shifted to anagen hair, and the CD4+ and CD8+ T cell infiltrates in the bulb area decreased in all cases. CD8+ T cells had almost disappeared from all portions of the follicles. It has been suggested that CD8+ T cells play a crucial role in the pathogenesis of AA. The absence of CD8+ T lymphocytes that responded to follicular autoantigens may induce hair regrowth in the grafted skin. In addition, the CD4+ human T cells that had infiltrated or still remained in the upper-middle portions including the bulge area accompanied the HLA-DR expression after grafting. Infiltrating or surviving T cell phenotypes and locations changed during the hair cycle in the grafts. These results indicate that the location of infiltrated T cells and their phenotypes may participate not only in hair loss but also in regrowth of hair in AA.

Alopecia areata: an autoimmune disease?

A wide range of hypotheses such as focal infection, trophoneuroses, and endocrine dysfunction, have been previously proposed to explain the pathogenesis of alopecia areata (AA). Currently, the most widely held belief is that AA is an autoimmune disease with cellular and/or humoral immunity directed against anagen hair follicle antigen(s). However, until recently evidence in support of an autoimmune mechanism of AA has been largely circumstantial. More fundamental evidence has recently been amassed in support of AA as an autoimmune disease by using animal models. These data include: 1) identification of cross-species hair follicle specific IgG autoantibodies, 2) The ability to induce AA in an animal model with transfer of skin from affected to naive individuals, and 3) the induction of disease by transfer of lymphocytes to human skin grafted to severe combined immunodeficiency mutant mice. A review of the previous and current data related to the autoimmune basis of AA is provided to put into perspective the future studies needed to definitively determine whether AA is an autoimmune disease.

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

A type of hair loss closely resembling human alopecia areata has been described in C3H/HeJ mice. In order to test the assumed analogy with human alopecia areata, we investigated the efficacy of treatment with the contact allergen squaric acid dibutylester. In 12 C3H/HeJ mice with alopecia areata an allergic contact dermatitis was induced and elicited weekly on one side of the back by topical applications of squaric acid dibutylester. Overt hair regrowth was observed only on the treated side of the back in nine of 12 mice. Histopathologic examination revealed a change in the distribution of the inflammatory infiltrate from a dense perifollicular lymphocytic infiltrate around the mid and lower regions of hair follicles in untreated skin to a uniform presence in the upper dermis in treated skin. Immunohistomorphometric studies revealed that treatment with squaric acid dibutylester increased the CD4+/CD8+ ratio from approximately 1:2 in untreated alopecia areata to 1:1 in treated alopecia areata. Additional immunohistochemical investigations showed an aberrant expression of major histocompatibility complex class I, major histocompatibility complex class II and intercellular adhesion molecule 1 on keratinocytes of the mid and lower parts of hair follicles in untreated alopecia areata. In successfully treated skin ectopic major histocompatibility complex class I and II expression was clearly reduced, whereas intercellular adhesion molecule 1 expression showed only minor changes. In conclusion, alopecia areata-like hair loss in C3H/HeJ mice responded to treatment with the contact sensitizer squaric acid dibutylester analogous to human alopecia areata. Moreover, successful treatment changes the aberrant expression of major histocompatibility complex class I and II in a way similar to that observed in human alopecia areata. These observations support the concept that alopecia areata-like hair loss in C3H/HeJ mice can be utilized as an appropriate model for the study of human alopecia areata.

Immunopathology of the human hair follicle

Although patients are told that, in many instances, their hair loss is precipitated by stress, they are certainly stressed and saddened by their alopecia. They would be elated with the ability to regrow their hair. Ideally, therapy would be specific and targeted at the cascade of inflammatory, cytokine-mediated, and mesenchymal events which lead to hair loss. Such is the case with infectious folliculitides: Pityrosporum folliculitis is cleared with antifungal agents, bacterial folliculitis is cleared with antibiotics, and herpetic folliculitis is treated with antiviral agents. Future studies of the hair follicle will perhaps unlock the mechanisms that drive and maintain normal hair growth. Until that time scientists will, no doubt, continue to be fascinated by the intricate developmental and immunologic mechanisms that drive this micro-organ of the skin.

Alopecia areata and cytomegalovirus infection in twins: genes versus environment?

BACKGROUND

Alopecia areata (AA) is hypothesized to be an organ-specific autoimmune disease mediated by T cells directed to the hair follicle. Genetic susceptibility may be conferred by HLA, and an environmental trigger, such as a viral infection, is suspected. The incidence of AA in the population is estimated to be 1.7%, with an average of one in four patients having a positive family history.

OBJECTIVE

Our purpose was to examine the concordance rate of AA among identical versus fraternal twins and the correlation between stress, cytomegalovirus (CMV) infection, and disease.

METHODS

Families with AA were solicited from dermatologists in the United States and through a Website on the Internet. HLA class 2 typing and identification of CMV early and late genes were performed by polymerase chain reaction (PCR) on genomic peripheral blood DNA. Serum antibodies for CMV were determined by enzyme-linked immunosorbent assay.

RESULTS

From 114 families, we identified 11 sets of monozygotic twins and 3 sets of dizygotic twins. The concordance rate was 55% for monozygotic twins and 0% for fraternal twins. Most identical twins were male. The severity of the AA phenotype varied and appeared most severe in the first affected twin. Five of 24 twins were CMV seropositive but CMV DNA was not detected in blood lymphocytes of any of the subjects when studied after the onset of AA. The presence of AA in twins was not correlated with evidence of CMV.

CONCLUSION

A 55% concordance rate in identical twins and AA occurring in families support a genetic component as well as possible environmental triggers that remain unknown.

Autoimmune hair loss (alopecia areata) transferred by T lymphocytes to human scalp explants on SCID mice

Alopecia areata is a tissue-restricted autoimmune disease of the hair follicle, which results in hair loss and baldness. It is often psychologically devastating. The role of T lymphocytes in this disorder was investigated with cell transfer experiments. Scalp explants from patients were transplanted to severe combined immunodeficiency (SCID) mice and injected with autologous T lymphocytes isolated from involved scalp. T lymphocytes which had been cultured with hair follicle homogenate along with antigen-presenting cells were capable of inducing the changes of alopecia areata, including hair loss and perifollicular infiltrates of T cells, along with HLA-DR and ICAM-1 expression of the follicular epithelium. Similar changes were not noted in grafts injected with scalp-derived T cells that had not been cultured with follicular homogenate. These data indicate that alopecia areata is mediated by T cells which recognize a follicular autoantigen.

Up-regulation of class II major histocompatibility complex and intercellular adhesion molecule 1 expression on scleroderma fibroblasts and endothelial cells by interferon-gamma and tumor necrosis factor alpha in the early disease stage

OBJECTIVE

To investigate the expression patterns of interferon-gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha), both of which are potent inducers of class II major histocompatibility complex (MHC) and intercellular adhesion molecule 1 (ICAM-1) expression, and their codistribution with HLA-DR and ICAM-1 in skin lesions, cultured fibroblasts, and peripheral blood mononuclear cells (PBMC) of systemic sclerosis (SSc) patients in different stages of disease.

METHODS

Investigations were carried out using immunohistochemistry studies, reverse transcriptase-polymerase chain reaction, dot-blot hybridization, and cytometric analysis. Serum levels of TNF alpha were determined by enzyme-linked immunosorbent assay.

RESULTS

In the early inflammatory stage of SSc, class II MHC and ICAM-1 expression could be detected on most endothelial cells and on fibroblasts located especially in perivascular areas surrounded by infiltrating lymphocytes, which belong to the T helper 1 phenotype expressing IFN gamma and TNF alpha. In this early disease stage, an enhanced expression of TNF alpha on cultured dermal fibroblasts and PBMC, as well as elevated serum titers of soluble TNF alpha, could be found.

CONCLUSION

These data suggest that class II MHC antigens and ICAM-1 on fibroblasts and endothelial cells are induced by IFN gamma and TNF alpha in an early stage of SSc after the influx of mononuclear-cells, and may be important in the putative autoimmune response and in the perpetuation of fibrotic processes in SSc.

Lymphocyte-mediated alopecia in C57BL/6 mice following successful immunotherapy for melanoma

Successful immunotherapy of established B16 melanoma metastases in C57BL/6 mice can be achieved by antibody-targeted interleukin-2 administration. This therapeutic effect is accompanied in approximately 20% of the animals by induction of a population of lymphocytes that migrates to and substantially disrupts the cytoarchitecture of the skin, which results in progressive alopecia. The histologic changes associated with the hair loss, i.e., peri-, and intrafollicular inflammatory infiltrates consisting of both activated CD4+ and CD8+ T cells, as well as expression of major histocompatibility complex class I antigens on subinfundibular follicle epithelium, are similar to those observed in human alopecia areata. Furthermore, the alopecic phenotype can be transmitted horizontally by passive transfer of lymphocytes from treated animals to naïve mice. Since lymphocytes from treated animals either lacking or displaying signs of alopecia are able to transmit these phenotypic changes to a similar percentage of naïve animals, the initiation of alopecia seems to be dependent on the coincidence of at least two different events: the presence of specific lymphocyte populations as well as specific features of the skin disclosing a target for these cells.

The pathogenesis of alopecia areata

Knowledge of the disease mechanisms in alopecia areata is discussed in the light of progress in hair biology, immunology, and genetics. A disease model is presented incorporating polygenic determination of disease severity and susceptibility with largely unknown trigger factors responsible for initiating clinical disease expression. Experimental systems including animal models for alopecia areata offer new opportunities for investigation of alopecia areata and developing novel therapies.

Clinical and histopathologic features of hair loss in patients with HIV-1 infection

BACKGROUND

Hair loss is common in patients with HIV-1 infection, and in black patients this loss may be associated with straightening. Possible causes are frequently present in patients with HIV-1. These causes include chronic HIV-1 infection itself and recurrent secondary infections, nutritional deficiencies, immunologic and endocrine dysregulation, and exposure to multiple drugs. However, histopathologic features have rarely been reported in these patients.

OBJECTIVE

The objective was to evaluate the changes in the hairs of a group of these patients and to identify the light microscopic and ultrastructural changes in the hairs and the histologic changes in the scalp.

METHODS

Hair plucks and pulls with scanning electron microscopy of the hairs were done on 10 patients with late-stage HIV-1 infection. In addition, scalp biopsy specimens were examined in both vertical and transverse sections.

RESULTS

All patients had telogen effluvium. Numerous apoptotic or necrotic keratinocytes were seen in the upper external root sheath follicular epithelium in addition to a mild to moderate perifollicular mononuclear cell infiltrate often containing eosinophils. Variable dystrophy of the hair shafts was also a consistent feature.

CONCLUSION

Although telogen effluvium is a common response to a wide spectrum of biologic stresses, the presence of apoptotic or necrotic keratinocytes within the upper end of the external root sheath epithelium and dystrophy of hairs may be markers of hair loss in patients with HIV-1 infection.

Alopecia areata: immunohistochemistry and ultrastructure of infiltrate and identification of adhesion molecule receptors

BACKGROUND

Alopecia areata (AA) is a noncicatricial alopecia with still unknown pathogenesis, but increasing evidence suggests that an immunologic process might be responsible for the disease.

MATERIALS AND METHODS

Nineteen patients with AA were studied with ten of them in the progressive phase of the disease and nine in the stabilized phase. Biopsies of both affected and unaffected skin were taken. For immunohistochemistry, monoclonal antibodies directed against CD3, CD4, CD8, CD10a, CD36, and HLA-DR antigens, were used, as well as antibodies directed against adhesion molecules ICAM-1, ELAM-1 and LFA-1. For electron microscopy (EM), specimens were fixed in glutaraldehyde-sodium cacodylate buffer, post-fixed in osmium tetroxide, and stained with uranyl acetate. For statistical analysis, sections from involved and uninvolved skin of each patient for each antibody, the sign test, Fisher's F-test, and the Tukey-Kramer test were used.

RESULTS

There was a rich infiltrate of CD4+ cells and CD1a+ cells, particularly in the perivascular zone of both unaffected and affected skin (here in the perivascular and in the peribulbar zone) in the progressive phase of AA. In the stabilized phase the infiltrate was scant, both in unaffected and affected skin and limited to the peribulbar area. Receptors of adhesion molecules (ICAM-2, ELAM-1, LFA-1) were strongly expressed, mainly at the microvascular level in both unaffected and affected skin in the progressive phase, but were only weakly or not at all expressed in the stabilized phase, again in unaffected and affected skin. Ultrastructural data confirmed the immunohistochemical findings and showed close contacts between infiltrating lymphocytes and Langerhans'-lineage cells mainly in the progressive phase.

CONCLUSIONS

Our results suggest that: 1) an immunologic process, apparently carried out by CD4+ lymphocytes and by dendritic CD1a+ and CD36+ cells, may play a key role at least in the early phase of the disease involving primarily microvessels and later on the bulbar area; 2) the expression of adhesion molecule receptors is involved at the beginning of the disease by mediating the adherence of leukocytes to endothelial cells and subsequent trafficking into the dermis.

Human leukocyte antigen-DQB1*03 alleles are associated with alopecia areata

Alopecia areata (AA) is characterized by hair loss in patches (patchy AA), over the entire scalp (AT, totalis), or universally (AU). An autoimmune mechanism has been hypothesized, because the inflammatory infiltrate targeted to the hair follicles includes activated T cells. To investigate whether or not genetic polymorphism of the human leukocyte antigen (HLA) region contributes to disease susceptibility, we used sequence-specific oligonucleotides and amplified genomic DNA to define HLA-DQA1, -DQB1, and -DPB1 alleles in a cohort of 85 white patients. The frequency of DQB1*0301 was significantly increased to 41% in all patients, and to 47% in AT/AU patients relative to controls (27%). Analyzed together, DQB1*03 alleles (DQB1*0301-*0303) were increased to 80% (all patients) and to 92% (AT/AU) (odds ratio = 12.14, p = 0.00003, corrected). This striking association implicates the DQB1*03 alleles in the pathogenesis of AA. DQB1*06 was decreased relative to controls (56%) in all patients (32%, odds ratio = 0.37, p = 0.0045, corrected). An increase was observed in the HLA-DRB1*11(DR5) allele DRB1*1104, which may result from linkage disequilibrium with DQB1 alleles. Sequence comparison among the allele products associated with AA indicates that the DQB1*03 alleles carry a unique proline at position 55 that is not present in alleles that are neutral or negatively associated with the disease. This highly significant association may exert considerable control over immune responsiveness and the initiation or persistence of a T-cell autoimmune response against the hair follicle.

Cytokine mRNA levels in Alopecia areata before and after treatment with the contact allergen diphenylcyclopropenone

Although the nature of the noxious signal and the anatomical target in alopecia areata (AA) are still unknown, it has been assumed that CD4+ T lymphocytes surrounding and infiltrating the hair bulb might trigger the hair loss. As these T lymphocytes do not promote cytotoxic activity we hypothesize that AA is triggered by cytokines. Topical immunotherapy with diphenylcyclopropenone (DCP) is at present the most effective approach. If it is true that AA results from a distinct cytokine pattern, we can hypothesize that the beneficial effect of DCP should be mediated by locally secreted cytokines during the contact allergy. Using semiquantitative reverse transcription-polymerase chain reaction with RNA extracted from scalp biopsies from patients with AA before and after successful treatment with DCP, and from healthy controls we detected a T-cell response with increased steady state mRNA levels for interferon (IFN)-gamma, interleukin (IL)-1 beta, and IL-2 in untreated AA of the totalis type. After DCP treatment, the IFN-gamma expression was reduced but still above the constitutive level found in controls, whereas mRNA expression of IL-2, IL-8, IL-10, and tumor necrosis factor-alpha was increased. Our results point towards cytokines involved in the pathogenesis in AA. A TH1 type cytokine pattern is present in untreated AA, and this is modified by cytokines secreted during DCP treatment. IL-10 has recently been described as an immunomodulator of the TH1 response and, therefore, we hypothesize that basal keratinocytes or lesional T cells secrete bioactive IL-10 after DCP application, resulting in an inhibitory effect on lesional T lymphocytes. This hypothesis would explain the effectiveness of DCP and implies the theoretical possibility of a response to topical or intralesional application of recombinant IL-10.

Comparative analysis of surface antigens in cultured human outer root sheath cells and epidermal keratinocytes: persistence of low expression of class I MHC antigens in outer root sheath cells in vitro

In the anagen human hair follicle, the epithelial cells from the infrainfundibular portion and the hair matrix cells express markedly lower numbers of major histocompatibility complex class I molecules than interfollicular epidermal keratinocytes. During the catagen phase of the hair cycle, class I expression on these cells increases, and activated macrophages aggregate around the follicle, which has led to the hypothesis that the cells to be resorbed are recognized by virtue of their low class I antigen expression. In the present study, we showed that, in vitro, outer root sheath cells also maintain a lower constitutive expression of MHC class I molecules compared with epidermal keratinocytes. In contrast, other surface antigens such as HLA-DR, -DP and -DQ, ICAM-1, LFA-3 and CD29, which are all known to participate in leucocyte-keratinocyte interactions, were similarly expressed in both cell types. Furthermore, interferon gamma strongly upregulated MHC class I and II and ICAM-1 expression in both cell types, whereas CD29 and LFA-3 remained unaffected. Tumour necrosis factor alpha, to a lesser extent, also upregulated MHC class I and ICAM-1 expression, but not class II expression. The differences in constitutive surface antigen expression of infrainfundibular outer root sheath cells compared with interfollicular epidermal keratinocytes emphasizes a distinct role of this cell type in the hair cycle, and possibly also in alopecia areata.

The aetiology and pathogenesis of alopecia areata

In common with a number of inflammatory autoimmune diseases, genetic factors including HLA class II associations have been identified in alopecia areata. No consensus has been reached on the identity of a specific disease target within the hair follicle in alopecia areata. Suggested candidate cell types include the dermal papilla cells, the keratinocytes of the matrix and presumptive cortex and the hair bulb melanocytes, but these need not be mutually exclusive. The pathogenesis is known to involve disturbance of immune function but there is no proof that an autoimmune mechanism is fundamental. We propose a pathogenetic model incorporating polygenic determination of disease susceptibility and severity with additional, possibly environmental, factors as triggers for disease expression.

Expression of class II major histocompatibility antigens by keratinocytes in cutaneous T cell lymphoma

BACKGROUND

Expression of various class II MHC antigens by lesional keratinocytes may play an important role in the pathophysiology of a wide variety of human dermatoses including cutaneous T cell lymphoma (CTCL). Nevertheless, there is relatively little information available concerning the concurrent expression of HLA-DR, -DP, and -DQ class II MHC antigens in CTCL. Therefore, our aim in this study was to determine the prevalence, localization, extent, temporal sequence, and consistency of class II MHC antigen expression by lesional keratinocytes in CTCL.

METHODS

We used a semiquantitative immunohistologic analysis to analyze HLA-DR, -DP, and -DQ expression by lesional keratinocytes in 66 skin biopsies obtained from 39 patients with CTCL.

RESULTS

Class II MHC antigen expression by keratinocytes was observed in 77% of cases. Expression was detected on the cytoplasmic membrane and within the cytoplasm. It varied among cases from focal to confluent. There was a hierarchy of antigen expression in terms of both extent and time course. HLA-DR was expressed first and most extensively, followed by HLA-DP and then HLA-DQ. Comparative studies of multiple serial or concurrent active lesions from 13 cases indicated that the overall pattern and extent of antigen expression was relatively constant within individual patients.

CONCLUSIONS

There was no apparent correlation between class II MHC antigen expression and the clinical stage of disease, the type of CTCL skin lesion, or the overall density of the lesional T cell infiltrate. The hierarchy of keratinocyte class II MHC antigen expression observed in this study paralleled that noted in earlier studies of cultured keratinocytes exposed to recombinant interferon-gamma in vitro. This suggests that lesional cytokine levels may be the critical factor governing class II MHC antigen expression by lesional keratinocytes in CTCL.

Antibodies to hair follicles in alopecia areata

Although alopecia areata is suspected to be an autoimmune disease, no direct evidence of an altered immune response to components of the hair follicle has been reported. We studied whether antibodies to normal human anagen scalp hair follicles are present in individuals with alopecia areata. Thirty-nine alopecia areata sera and 27 control sera were tested by Western immunoblotting for antibodies to 6 M urea-extractable proteins of normal anagen scalp hair follicles. At serum diluted 1:80, all alopecia areata subjects (100%), but only 44% of control individuals, had antibodies directed to one or more antigens of approximately 57, 52, 50, 47, or 44 kD. The incidence of antibodies to individual hair follicle antigens in alopecia areata was up to seven times more frequent than in control sera and their level up to 13 times greater and was statistically significant for all five antigens. Tissue specificity analysis indicated that these antigens were selectively expressed in hair follicles. These findings indicate that individuals with alopecia areata have abnormal antibodies directed to hair follicle antigens, and support the hypothesis that alopecia areata is an autoimmune disease.

Immunohistological study of the development of the cellular infiltrate in the pelage follicles of the DEBR model for alopecia areata

The Dundee experimental bald rat (DEBR) undergoes hair loss associated with perifollicular infiltrates of mononuclear cells (MNC), a pathological characteristic of human alopecia areata (AA). To investigate further the pathogenesis of the disease in this animal model, we have studied the development, composition and extent of the perifollicular MNC infiltration in young (6-week-old), prelesional (3-month-old), active lesional, and established lesional DEBR rats, using 6-week- and 6-month-old Wistar rats as normal controls. The proportions of hair follicles showing infiltration by MNC and their main subsets were determined using immunohistochemical staining of serial cryostat sections of flank skin biopsies. There was a good correlation between the degree of leucocyte (OX-1+) infiltration of anagen hair follicles and the development of hair loss. In 6-week-old DEBR skin, there were few perifollicular cells expressing MHC class II, with positively stained dendritic cells in the dermis above the sebaceous gland. There was a sparse perifollicular distribution of CD4+ cells (W3/25) and macrophages (ED-1+). No CD8+ cells (OX-8+) were seen associated with DEBR hair follicles, and only small numbers were present in Wistar rats. In prelesional DEBR rats there was an increased perifollicular presence of MHC class II+ cells, macrophages, and particularly of CD8+ cells, with little change in CD4+ cells. Active and established lesional rats, i.e. animals with overt loss of hair, showed a significant increase in the degree of MNC infiltration and the proportion of infiltrated follicles, the majority of which were in dystrophic anagen. In the perifollicular infiltrate the CD4+:CD8+ ratio was approximately 2:1. An intrafollicular infiltrate was prominent, and was composed of CD8+ cells and macrophages, with bulbar and suprabulbar keratinocytes expressing MHC class II antigens. CD4+ cells were not detected in follicular epithelium. ICAM-1 expression correlated with MNC infiltration. These results show marked similarities to lesional human AA. They also focus on a possible active role for CD8+ cells in the pathogenesis of hair loss in the DEBR rat.

HLA and ICAM-1 expression in alopecia areata in vivo and in vitro: the role of cytokines

To investigate the hypothesis that aberrant HLA and adhesion molecule expression in alopecia areata (AA) are secondary to local release of interferon-gamma (IFN-gamma) or other cytokines, we have studied HLA ABC, -DQ, -DR and ICAM-1 expression by immunohistochemistry, and compared patterns of expression in lesional tissue sections with those observed in hair follicles maintained in short-term organ culture, both from normal individuals and non-lesional sites in AA patients. The organ cultures were supplemented with IFN-gamma, tumour necrosis factor-alpha (TNF-alpha), and granulocyte-macrophage colony stimulating factor (GM-CSF), in a range of doses. In lesional AA tissue sections, there was close spatial correlation of ICAM-1 with HLA-DR; prominent staining being noted in the pre-cortical matrix and dermal papilla (DP) of lesional anagen follicles. In cultured follicles, dose-dependent induction of HLA class I, DR and ICAM-1 by IFN-gamma, and HLA class I and ICAM-1, but not HLA-DR, by TNF-alpha was observed in follicular epithelium, mainly in the outer root sheath (ORS). The findings in these cultures were the same in follicles derived from normal individuals and AA patients. Cytokine-induced patterns of HLA and ICAM-1 expression observed in vitro in cultured follicles differed significantly from those observed in vivo in lesional tissue sections. In particular, IFN-gamma failed to induce HLA-DR expression in the pre-cortical matrix and dermal papilla (DP), sites where this is usually observed in AA. The results suggest local cytokine release is not the sole determinant of aberrant HLA-DR expression in AA.

Effects of cytokines, anti-cancer agents and cocarcinogen on DNA synthesis in hair bulb cells

We analysed the effects of cytokines, anti-cancer agents and cocarcinogen on DNA synthesis in human hair germinative cells cultured in serum-free media. Epidermal growth factor and gamma interferon were found to inhibit DNA synthesis slightly, while strong inhibition was demonstrated by doxorubicin, cytosine arabinoside and tetradecanoyl-phorbolacetate. Basic fibroblast growth factor had very little influence on DNA synthesis. This organ culture model in serum-free media is a useful method by which to examine the effects of various cytokines and drugs on DNA synthesis in hair germinative cells and/or to study the pathogenesis of various alopecia diseases.

Topical minoxidil in alopecia areata: no effect on the perifollicular lymphoid infiltration

The therapeutic value of topical minoxidil in alopecia areata (AA) has been investigated in recent years, with variable results. Although the mechanism whereby minoxidil may stimulate hair regrowth in some cases of AA has not yet been elucidated, there have been reports of a decrease in the perifollicular infiltrates of mononuclear leukocytes (MNC)--particularly T lymphocytes--that characterize this condition, in patients "responding" to topical minoxidil. In a randomized and double-blind study, we have investigated the effect of 5% topical minoxidil versus placebo (vehicle alone) on the extent and composition of the perifollicular MNC infiltration in 20 patients having extensive AA (26-99% scalp hair loss). The proportions of hair follicles showing perifollicular infiltration by MNC and their main subsets were determined with histologic and immunohistochemical stainings of scalp biopsies obtained before treatment, after 12 weeks of randomized double-blind minoxidil versus placebo treatment, and after 12 additional weeks during which all patients received minoxidil. Six of the patients showed cosmetically acceptable hair regrowth (CAHR) at the end of the 24 weeks and this was associated with a significant decrease in the proportions of follicles infiltrated by total T and B lymphocytes, macrophages, and Langerhans cells at week 12, and by total T lymphocytes at week 24. However, no significant differences in the extent or composition of the perifollicular infiltrates were detected at week 12 between patients receiving minoxidil and placebo, or between the week-12 and week-24 biopsies of those patients who first received placebo and then minoxidil. These findings indicate that in AA the reduction in perifollicular T-cell infiltration associated with CAHR is not attributable to an effect of topical minoxidil.

Expression of T6 antigen on keratinocytes in alopecia areata

The expression of T6 antigen within hair follicles in alopecia areata was studied using the APAAP technique (alkaline phosphatase monoclonal anti-alkaline phosphatase method). Scalp biopsies were taken from 15 subjects with alopecia areata, nine in an active stage and 6 in a stationary stage of the disease. Six-micrometer-thick frozen sections were stained with OKT6 antiserum. OKT6 are monoclonal antibodies raised against human thymocytes; they cross-react with epidermal Langerhans cells and are a highly specific marker. Nine of the specimens displayed T6 staining on keratinocytes in the bulb matrix, and all nine were from the subjects presenting the active stage of disease. The specimens from the other six biopsies, from subjects in a stationary stage, did not show T6 staining of bulbar keratinocytes. Moreover, in four of the active-stage cases we found T6 staining also on epidermal keratinocytes.

Papular acrodermatitis of childhood (Gianotti-Crosti disease)

An 11-year-old boy had lentil-sized lichenoid papules, localized to the limbs and trunk, together with acute, nonicteric, hepatitis B surface antigen-positive hepatitis. The clinical picture and course were typical of Gianotti-Crosti disease. Monoclonal antibodies were used to study the lymphocyte subpopulations and surface antigens in the inflammatory infiltrate in frozen sections of a skin biopsy specimen. The results provide data on the pathogenic mechanism of the papular exanthem.

Dendritic cells and dinitrochlorobenzene (DNCB): a new treatment approach to AIDS

Recent studies suggest that antigen-presenting cells (dendritic cells) may play a key role in the pathogenesis of human immunodeficiency virus (HIV) infection. This observation makes new immunomodulatory treatment strategies desirable. Topical dinitrochlorobenzene (DNCB) is discussed as a possible treatment modality in the context of its proven therapeutic uses and its immunomodulatory effect on dendritic cells. DNCB may be a safe, inexpensive, and widely available treatment option for HIV disease.

Expression of class II-MHC antigens in the dermis of patients with progressive systemic sclerosis

Expression of class II major histocompatibility complex (MHC) antigens on normally negative cell types may convert them into effective antigen-presenting cells. It was therefore of special interest to elucidate whether the main cell populations involved in progressive systemic sclerosis (PSS) express class II antigens on their surfaces and participate in the initiation and/or perpetuation of a cellular immune response in the connective tissue. Immunofluorescence studies on frozen skin sections of scleroderma patients using double-staining techniques revealed a pronounced dermal mononuclear cellular infiltrate with signs of activation manifested by expression of MHC class II antigens in the acute phase of the disease. Most endothelial cells of the papillary and deeper dermal vessels were class II-positive as seen in other inflammatory dermatoses. Moreover, class II antigen-positive fibroblasts were found, especially in the deeper dermis within infiltrated areas around blood vessels. MHC class II molecules were also detected in higher density and on increased numbers of perivascular dermal dendrocytes. On all cell types, HLA-DP was much less frequently expressed than HLA-DR, but more frequent than HLA-DQ. However, in the chronic phase of the disease, with reduced inflammation and increasing sclerosis, MHC class II antigen expression on dermal fibroblasts was again diminished or even absent, as seen in normal and non-PSS inflammatory control biopsies and clinically unaffected skin of scleroderma patients in the acute inflammatory disease stage. Our data speak against a primary expression of class II molecules on PSS-fibroblasts. It seems more likely that Ia-antigens on fibroblasts and an increase of MHC class II positive dermal dendrocytes are induced in an early stage of the disease, i.e., after the influx of the mononuclear infiltrate, most probably by mediators released from these cells. Since an enhanced transcription rate of collagen genes in fibroblasts surrounded by infiltrating cells has been described, this early expression of class II MHC antigens does not seem to play a central role in the induction phase, but rather, may be important in the perpetuation of fibrotic processes in scleroderma.

Increased HLA-DR+ T-lymphocyte population in peripheral blood of alopecia areata

The populations of activated T-cell subsets [HLA-DR(+)-Leu 4+ cells, interleukin 2 receptor positive (IL-2R+)-Leu 4+ cells] in the peripheral blood of patients with alopecia areata (AA) were investigated using double direct immunofluorescence staining. Fifty-eight patients with AA were classified into one of three types: those with inactive single AA (type 1) lesions, active multiple alopecia areata (MAA) lesions and active alopecia totalis (AT) (type 2) and chronic alopecia universalis (AU) (type 3). Compared to normal controls, high percentages of HLA-DR(+)-Leu4+ cells were detected in types 2 and 3 AA patients, but not in type 1 AA patients. These findings suggest that T cells are activated in the peripheral blood of active MAA, AT and chronic AU.

Immunohistologic and ultrastructural comparison of the dermal papilla and hair follicle bulb from "active" and "normal" areas of alopecia areata

The "active" edges of patches of alopecia areata and normal areas from the same scalp (i.e., bearing normal terminal hair) from seven patients with alopecia areata were investigated immunohistologically. Similar areas from a further eight patients were examined using light and electronmicroscopy. "Active" and "normal" areas of alopecia areata scalps were immunohistologically similar and varied from normal controls in the number, distribution, and ratio for T4 and T8-positive cells. Similarly the ultrastructural changes seen in the "active" areas when compared to normal controls were also present in the "normal" areas of alopecia areata scalps. The most significant differences found between normal "control" follicles and both "active" and "normal" areas of alopecia areata scalps were the polymorphic nature of the dermal papilla cells and the loss of cellular organization within the dermal papillae taken from alopecia areata scalps. In addition, the junction between the dermal papilla and the bulb of the hair follicle, the dermo-epithelial junction of the hair follicle bulb, demonstrated critical changes in follicles taken from both "active" and "normal" areas of alopecia areata scalps. These results support the suggestion of a subclinical state of alopecia areata and indicate that further work on the etiology of alopecia areata should be directed towards the "normal" areas of alopecia areata scalps, in particular the cells of the dermal papilla and the dermo-epithelial junction of the hair follicle bulb.