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Third international research workshop on alopecia areata - Introduction The Third International Research Workshop on Alopecia Areata was held in Washington DC on the 5th November 1998 at the Renaissance Mayflower Hotel. The conference was organized jointly by the National Alopecia Areata Foundation and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) which is part of the National Institutes of Health (NIH). The intention was to bring together investigators and clinicians involved in alopecia areata research and treatment of patients. The primary aim was to present and discuss the latest advances in our understanding of alopecia areata. Over 250 individuals attended this one day workshop and this was a significant increase over the Second International Research Workshop on Alopecia Areata held four years ago when 200 people attended. Part of the increase can be attributed to organizing the workshop to be held the day before a much larger 2 day conference on hair research held in the same hotel (Second Intercontinental Meeting of Hair Research Societies). However, there was clearly much interest from attendees who had come from Europe, Australasia, North and South America, and Japan. The workshop was arranged with seminars from speakers presenting their latest work during the day plus poster presentations from other research groups and clinicians to be viewed at a reception in the evening. Below is my brief summary of the workshop subdivided under appropriate categories of research. Abstracts and papers derived from the conference have been published in the Journal of Investigative Dermatology (JID).
Seminars - Animal models for alopecia areata The first block of seminars focused on animal models of alopecia areata. Animal models will provide crucial information about the induction and pathogenesis of alopecia areata. Advantages compared to humans include; short life span enabling rapid evaluation of experiments where physical age may be a factor, the advantage of monitoring disease progression throughout onset including examinations in advance of overt hair loss to see what systemic activity might precede actual onset of alopecia areata, and use of inbred strains (each animal has the same genetic makeup) that make studies to identify susceptibility genes for alopecia areata much easier compared to the use of outbred humans (each individual has a different genetic composition). Animal models will provide an important tool in the investigation of genetic and environmental activation factors, disease pathogenesis, and development of new and improved treatment protocols. Alopecia areata in animals: new insights The C3H/HeJ mouse model for alopecia areata was discovered around the time of the previous alopecia areata workshop four years ago. Up to 20% of this strain of mice spontaneously develop patchy non scarring alopecia. Frequently this hair loss expands and may become universal. Spontaneous remission may occur in up to 3% of affected mice. The mice are otherwise healthy. In addition to C3H/HeJ mice, it was reported that spontaneous alopecia areata has also been discovered in mice from strains such as A/J, C3H/HeN/J, and HRS/J heterozygotes among others. While it has been claimed that alopecia areata is rare in non human species it is clear that mice of several strains are predisposed towards alopecia areata. Analysis of these mouse strains may help identify susceptibility genes and environmental factors important in alopecia areata development. These results may be directly related to the human disease as mice have over 80% genomic homology with humans. Of particular interest was the report that alopecia areata could be induced in normal haired mice from the C3H/HeJ mouse strain. Skin grafts from affected mice could be given to normal haired recipients who then developed alopecia areata 8-10 weeks after grafting. This consistent model will be useful to examine what happens in the system before hair loss occurs. Screening to observe which genes are active in the skin around and in hair follicles before overt alopecia has already begun using this model. The ability to induce alopecia areata in a model also suggests that while individuals may be genetically predisposed towards alopecia areata just having the genes does not automatically mean the individual will develop the disease. It seems that overt hair loss must be activated, most likely by factors in the environment. The investigators also noted that alopecia areata could be induced by taking inflammatory cells from alopecia areata affected animals and transferring them to normal haired recipients. Again, hair loss developed 8-10 weeks after the procedure. This indicates that inflammatory cells are capable of inducing hair loss even though hair follicles are potentially immune privileged sites. It also provides the opportunity for different inflammatory cell types to be isolated to see which ones have pathogenic potential and which ones are not important in alopecia areata. This knowledge may lead to new treatments that work just on those inflammatory cells that are known to cause hair loss. Alopecia areata transferred by T lymphocytes to human scalp explants on SCID mice This recognition that inflammatory cells are important in alopecia areata was confirmed and expanded upon by research conducted in Israel where grafts of human skin affected by alopecia areata were transferred to nude mice. Nude mice have a natural immune deficiency that allows them to accept grafts from different species. The grafts regrew hair indicating that it is the immune system that blocks hair growth in alopecia areata. The investigators took inflammatory cells from affected patients and isolated different cell types and injected these into the grafts of now regrown hair. They found that certain cell types, particularly CD8 cytotoxic T cells, were able to promote renewed hair loss. This indicates that some of these cells are involved in causing alopecia areata. This is a significant advance as previously there was no direct evidence to suggest that inflammatory cells could cause hair loss even though it had been suspected for many years. It also indicates that hair follicle autoantibodies may not be crucial in alopecia areata development. Alopecia areata and universalis in the Smyth chicken model for spontaneous autoimmune vitiligo The third seminar focused on a potentially new animal model for alopecia areata. The Smyth chicken model is derived from the SL strain. Some of these chickens were found to have vitiligo. The chickens initially had normally pigmented feathers but on reaching teenage chicken years started to loose pigment from their feathers. This was shown to be due to non scarring inflammation similar to vitiligo. It was noted that some of the chickens with vitiligo also developed feather loss. The loss could be in multiple patches that could expand over time and may become universal in some chickens. This new model may help in identifying more alopecia areata susceptibility genes and may suggest a link between vitiligo, melanogenesis (pigment production) and development of alopecia areata.
Seminars - Genetics of alopecia areata Genetic basis of alopecia areata: HLA in long-standing disease Two seminars focused on genetics research using DNA taken from humans with alopecia areata. The investigators were attempting to find genes that were consistently present in people with alopecia areata compared to the general population. This might indicate that such genes make someone more susceptible to alopecia areata and may even suggest that these genes are actively involved in the pathogenesis of hair loss. Many autoimmune diseases are known to have certain types of HLA antigen genes associated with them (See immunology section for explanation on what HLA antigens are). Both investigators focused on finding HLA associations in alopecia areata and were able to independently confirm each others results. The broad antigen DQ3 was identified as being associated with general alopecia areata susceptibility. HLA alleles DQB1*0301, DRB1*1104, and DRB1*0401 were found in highly significantly increased frequency in people with alopecia totalis/universalis. DRB1*1104 was also found in highly significantly increased frequency in people with patchy alopecia areata but the other two alleles were not. The investigators suggest that amino-acid sequencing of the antigen binding grooves of these HLA antigens may indicate the structure and identity of the elusive alopecia areata antigens. Genetic basis of alopecia areata: linkage analysis The second research group reported similar findings they had identified independently of the first group. They showed that the broad HLA antigens DR4, DR11 and DQ3 were increased in association with alopecia areata. They indicated that alleles DQB1*0301 and DRB1*1104 were general alopecia areata susceptibility genes and that DQB1*0301 in particular was associated with alopecia totalis/universalis. They also suggested one gene that may confer resistance to alopecia areata called DRB3*52a. The similar findings from both groups support each other and suggest these HLA genes may be markers for alopecia areata susceptibility. T cell repertoire in alopecia areata The third seminar took a different approach. Here the investigator took lymphocyte cells from alopecia areata affected C3H/HeJ mice and tried to identify if there were certain cell clones that predominated. Typically in all autoimmune diseases the T cell inflammatory response is directed to just a few antigens. In turn, this means only those inflammatory cells specific for these antigens proliferate and actually cause the disease. The investigator found T cell clones expressing a Vbeta8.2/Jbeta2.5 T cell receptor arrangement were predominant in alopecia areata affected mice. These dominant cells may be characterized further to see what antigen this particular cell type is targeting. In theory, antibodies could be made against just this cell type to render them inactive but leaving the rest of the immune system unaffected.
Seminars - Immunology of the hair follicle and alopecia areata Immunology of the hair follicle An important factor that may play a role in alopecia areata is that normal hair follicles are immune privileged. Immune privilege means that the immune system cannot see all of the antigens in hair follicles, some are hidden from view. These hidden antigens might be inappropriately exposed and cause the immune system to respond as the immune system has not seen these antigens before and may not recognize them as being harmless. Some research groups are trying to understand how the hair follicle might be immune privileged and how this protection might break down in alopecia areata. Researchers in Berlin, Germany have noted that HLA antigens (MHC) are not expressed in normal hair follicles. They have also shown that immunosuppressants such as alpha-MSH, ACTH, and TGF beta are produced locally in hair follicles and this may further bolster hair follicle immune privilege. The investigators hypothesize that something goes wrong and that there might be up regulation of HLA antigens or down regulation of locally produced immunosuppressants and this may allow the immune system to see hair follicle antigens. Further work on immunosuppressants is in progress. The pathogenetic role of cytokines and T cells in alopecia areata Another report from Germany examined the potential for cytokines to play a part in alopecia areata. The investigators suggested an explanation for how patches of alopecia areata develop while other areas of hair can remain unaffected. They thought that an initial trigger caused inflammation in just one or two hair follicles. This trigger might be any physical or chemical disruption of the hair follicle’s immune privilege. When the inflammatory cells arrive to respond to the abnormal hair follicle they begin to make cytokines. These are chemical signals that the inflammatory cells use to communicate with each other. These cytokines may do several things. They will recruit more inflammatory cells to the local area and they may have a direct effect on hair follicle growth. Cytokines such as IL-1 TNFalpha and IFNgamma have all been shown to directly promote hair loss. Because they are chemicals, the cytokines may spread out from the area where they are made similar to a stone dropped in a pool makes ripples that spread over the surface of the water. The cytokines that spread out will recruit inflammatory cells to areas neighboring the original inflammatory site. These cells may then make the patch of hair loss expand. The cytokine diffusion may also prohibit hair growth over a larger area. In support of this idea the investigators showed several pictures of alopecia areata patches that had expanded and had hair regrowth in the center of the patches that progressed in concentric circles. They also noted that patchy hair loss could also occur after inflammation and cytokine production in seborrheic eczema, alopecia from syphilis, and T cell lymphomas. The investigators believe a treatment obstructing a key cytokine’s production and/or stopping CD8 cell activity would be an effective treatment for alopecia areata. Immunophenotypic profiles during topical immunotherapy of alopecia areata in mice and rats with diphencyprone A third report discussed the results of using a contact sensitizing agent diphencyprone (DCP) on rodent models for alopecia areata. C3H/HeJ mice and DEBR rats with hair loss had one side treated with the DCP and the other with the drug vehicle as a control for comparison. Both mice and rats showed a good response and had hair regrowth generally limited to the immediate area of application of the drug. It was found that this was associated with a reduction of inflammatory cells, notably CD8 cells around hair follicles, and increase in inflammation higher up in the dermis. There was also a decrease in ICAM-1 expression (ICAM-1 is an important signal to inflammatory cells). The investigators suggest that the animal models will be useful for screening new and improved therapies. They also indicate that new treatments focusing on CD8 cells may be of most benefit.
Seminars - Genetics of hair loss Molecular pathology of papular atrichia: hairless gene mutation in humans and rhino mice Two seminars looked at hair loss due to genetic mutations not directly associated with alopecia areata. The intention with this form of research is to define key genes involved in hair growth and cycling. This information may eventually identify new treatments that directly promote hair growth as well as help us understand why and how hair follicles cycle through growth and rest. The first seminar looked at the hairless gene in humans. Briefly, the investigators confirmed that the human hairless gene promotes a disease now called congenital atrichia and in some cases individuals will develop papular atrichia (same thing but with skin papules). The investigators were criticized for previously calling the disease alopecia universalis congenital which everyone now agrees is inappropriate as the name can be confused with inflammatory alopecia universalis. The investigators had identified several families that had this genetic hairless gene trait from Pakistan and Ireland. People with the hairless gene can be born with hair but this hair is rapidly lost during childhood and almost never regrows. They have universal body hair loss (not alopecia universalis!). Most intriguingly, the investigators had begun to screen people previously diagnosed as having inflammatory alopecia universalis. They found the a very VERY small proportion actually had a variation on the hairless gene defect. It was shown that people with a hairless gene had massive and premature cell apoptosis (cell destruction) in the hair matrix cells suggesting that the first hair cycle into catagen is totally and irreversibly disrupted. Hair defects in Hoxcl3 mutant mice The second seminar looked at a Hox gene. Hox genes are a bunch of genes involved in defining how an embryo grows and forms different appendages. We know that Hox genes are important in defining the position, density, and development of hair follicles in an embryo as well as being involved in growth of the limbs, eyes, and nails. Hoxcl3 seems to be involved in controlling other gene products notably hair keratins. The investigators set about developing a mouse strain where the mice had a single gene mutation in Hoxcl3 making it inactive. By looking at these mice the investigators tried to define what growth and development defects occur if the Hoxcl3 gene was dysfunctional. They found that mice with Hoxcl3 defect cannot synthesize hair keratin properly. Most of the mice had little hair and what hair was present was brittle and easily broken off. They also found that the tongue papillae were very brittle, and nails were misshaped and overgrown. It would seem that this gene is very important in putting together a fully functional hair follicle.
There were over 30 posters presented at the one day workshop. Rather than go through each individual poster I have condensed the information. I have not covered all the posters, unfortunately I did not have time to read each poster in detail. Many were studies using animal models and in particular the C3H/HeJ mouse model. Several posters looked at the response of alopecia areata affected mice to treatments. Squaric acid dibutyl ester (SADBE) is a topical contact sensitizer and was used on mice. One poster showed that the mice had a good response to the treatment with clear hair regrowth. It was shown that this was associated with a reduction of inflammation around hair follicles and an increase in inflammation high in the dermis. Mice treated with SADBE had serum samples taken and analyzed in another poster. It was found that mice could have high levels of hair follicle specific autoantibodies before and after treatment but that the concentration of autoantibodies was reduced after treatment. A third poster looked at how the hair follicles changed before and after treatment. They found that hair dystrophy reduced, the telogen o anagen hair follicle ration was reduced, and melanin incontinence was reduced. However, the hair follicle problems were not entirely removed and that small residual effects were still apparent. It was clear that SADBE treatment was acting through brute force to turn alopecia areata around rather than having a selective effect. Another study involving rats with alopecia areata looked at a potentially new treatment for alopecia areata called Leflunomide. This drug is an immunosuppressant, it acts to block IL-2 cytokine activity, and it is used to treat autoimmune arthritis. The drug was given orally to rats. It was found to promote some hair growth. Some rats responded much better than others and while some had good hair regrowth others responded with little or no regrowth. An experimental treatment was used on alopecia areata affected mice involving use of a unique monoclonal antibody that is CD44v10 specific. It was shown that this antibody can stop onset and progression of hair loss. CD44v10 is involved in activating CD4 and CD8 cells to migrate into tissue and attack antigenic targets. Use of CD44v10 in humans is not practical but the experiment points towards CD4 and/or CD8 type cells being the key destructors of hair follicle tissue. 5% topical minoxidil was used to treat alopecia areata in a double blind study involving 30 volunteers. 1ml was applied twice daily for 12 weeks. Later all volunteers received minoxidil for a further 36 weeks. After 12 weeks no significant differences were found between volunteers using minoxidil and those using a placebo. After 48 weeks 12 of 25 with patchy hair loss had a reasonable hair growth response. Of 5 with total scalp hair loss there was little or no hair regrowth. Skin irritation and facial hypertrichosis were side effects seen in one volunteer each. This seems to suggest 5% minoxidil may be of benefit to those with patchy alopecia areata but not extensive hair loss. Clinical dermatologists at the second international workshop were asked to complete a questionnaire about how they treat alopecia areata. In total 38 different treatments including combination treatments were in use three years ago around the world. The most common treatment was use of intralesional steroids for adults (typically 20-40mg per visit) and topical steroids for children. Use of steroids varied widely in makeup, concentration, and delivery indicating personal preference of the dermatologist played a significant part in how alopecia areata was treated. Extensive alopecia was most frequently treated with a contact sensitizing agent such as; diphencyprone (47-54%), Squaric acid dibutyl ester (25-31%), and dintirochlorobenzene (15-28%). Up to 30% of children with AA were treated with an immunotherapy of which 12% received potentially mutagenic DNCB. One poster looked at biotin treatment (20mg per day) for alopecia areata. After 3 months in 52 volunteers, 2 children had complete hair regrowth and 3 adults plus 2 children had 50% regrowth. Another 5 cases had a little regrowth. The conclusion was that the response rate was too low to be regarded as significant compared to spontaneous hair regrowth potential and that biotin was not effective for alopecia areata over three months of treatment.
One study looked at susceptibility genes in C3H/HeJ mice. A pilot study looked at these mice for potential chromosome locations that may contain genes that may be involved in alopecia areata and/or in high immunoglobulin production with particular reference to inflammatory bowel disease. Three gene loci were identified one of which was common to both high immunoglobulin production and alopecia areata susceptibility. A region of mouse chromosome 6 may contain one or more genes involved in inflammatory events associated with alopecia areata and/or inflammatory bowel disease. Intriguingly, a separate poster looking at genes in people with alopecia areata independently identified the same chromosome region (which in humans is actually on chromosome 2) as being a location for alopecia areata susceptibility genes. They suggested it was a cytokine gene polymorphism of IL-1 that was involved. It would seem that mouse chromosome 6 (region equates to human chromosome 2) is a hot spot for one or more genes involved in inflammation and potential disease susceptibility. One study looked at how variations in clinical presentation might indicate genetic heterogeneity. That is, different people with different forms of alopecia areata may have different susceptibility genes. It was found that people with patchy alopecia areata were much more likely to have a family history of the disease compared to people with totalis or universalis. A family history was also more frequent in women than men. Associated autoimmune disease was almost exclusively limited to women with alopecia areata. Having nail problems made the prognosis for spontaneous recovery less likely.
Posters - Disease pathogenesis Dr Daly reported on calcitonin gene related peptide (CGRP) deficiency in people with alopecia areata. Details are posted in the Alopecia Areata section of this web site. This CGRP deficiency was confirmed by discussion with another investigator looking at neurobiochemical activity in hair follicles. One poster screened alopecia areata patients for thyroid dysfunction and found up to 37% of patients with some problem indicating people with alopecia areata could and should be screened for thyroid dysfunction. Many other posters were available and I suggest you obtain a copy of the published symposium proceedings that should be available in the first quarter of 1999 from the Journal of Investigative Dermatology. The national Alopecia Areata Foundation should be able to keep you informed.
On the academic research side, people are getting much more focused on what needs to be done to prove alopecia areata is truly an autoimmune inflammatory mediated disease (or indeed to discount this hypothesis!). At the Second Research Workshop on Alopecia Areata the identification of hair follicle autoantibodies was the big discovery. Four years on and we have drawn the conclusion that while autoantibodies may have a pathogenic role in disease progression they are probably not the key cause of alopecia areata. Using animal models, investigators are homing in on inflammatory cells as the ones that promote hair loss and in particular the CD8 T cell type is receiving a lot of attention with some focus on CD4 cells that are helper cells for CD8 cells. Identifying particular pathogenic cell subtypes of CD8 cells is possible and doing this may reveal what particular antigenic targets are involved in alopecia areata. It also indicates these cell types are prime candidates for new treatment interventions. Genetics research is beginning to expand and progress. New chromosomal locations beyond the HLA region have been suggested as potential areas harboring alopecia areata susceptibility genes. Genetic research is a long term project but may ultimately elucidate why, how, and who gets alopecia areata. One the clinical side, most clinicians are now realizing that alopecia areata is not a homogeneous disease. Clearly different forms of alopecia areata indicate different genetic and environmental contributing factors. Different presentations may also indicate different future prognoses. The need for standardized patient questionnaires and recording of information is important to compare and contrast different studies conducted in different clinics. To this end, a standardized method to diagnose and classify patients was put forward at this conference. Behind the scenes there was a movement to develop a central repository for clinical data and a DNA bank for patients with alopecia areata. Details have yet to be discussed. Centralized data readily available to all investigators will help significantly in statistical analysis of alopecia areata pathogenesis and treatment success rates. DNA banks will aid genetic analysis and identification of alopecia areata susceptibility genes. Although there were few new treatments reported at this conference the development of animal models with potential for screening new therapies has gained the attention of several academic and commercial investigators. Behind the scenes, at least two pharmaceutical companies expressed interest in screening drug compounds for potential use in alopecia areata (but I’m not telling which ones, so there!). Let’s see if they put their money where their mouth is. This is a significant change from three years ago when commercial enterprise showed no interest in alopecia areata. We can also thank the relatively recent interest in developing treatments for androgenetic alopecia as promoting interest in treating other forms of hair loss. Finally, what goes on behind the scenes of conferences is often more important than the seminars and posters. New collaborations are made, research discussed, information exchanged, and deals done. Look to the next international workshop for the results of the contacts made at this conference. |
