2001-2002 NAAF Research Grant Awardees

1. Nazila Barahmani, M.D., (pictured) and Madeleine Duvic, M.D., both at the University of Texas M.D. Anderson Cancer Center, Houston, Texas, will further studies on “HLA (Human Leukocyte Antigen) Susceptibility in Alopecia Areata.”

Alopecia areata is an organ-specific autoimmune disease mediated by a class of white blood cells called T-lymphocytes that attack hair follicles. Current data suggests that alopecia areata is a complex genetic trait caused by the interaction of multiple genes and environmental factors, since only half of identical twins are both affected by the condition. Complex traits are characterized by the fact that the mode of inheritance does not follow any of the known Mendelian patterns, the manner in which genes and traits are passed from parents to children. (Examples of Mendelian inheritance include autosomal dominant, autosomal recessive, and sex-linked genes.)

The pathogenesis of alopecia areata may be determined in part by genes residing within the human major histocompatibility complex (MHC), which encodes human leukocyte antigens (HLA). (Leukocytes comprise the different types of white blood cells having varied functions, which help to combat infection.) Previous studies in both unrelated patients and in families support both genetic linkage and transmission by descent association between alopecia areata and specific HLA Class II alleles. (An allele is an alternate form of the gene for a specific trait.) The HLA region may be important in conferring susceptibility to developing alopecia areata, but whether HLA alleles themselves or products of closely associated genes are most important is not yet known.

The goal of this study is to closely examine the relationship between highly variable genetic markers and the alopecia areata trait along the HLA locus. This information should reveal the location of genes most closely connected to alopecia areata. Finding the genes contributing to alopecia areata would lead to a better understanding of the basic mechanism of the disease, as well as to more effective treatments or prevention methods. In addition, it can assist in the understanding of the mechanisms involved in the onset of other related autoimmune diseases.

2. Vladimir Botchkarev, M.D., Ph.D., Boston University School of Medicine, Boston, Massachusetts, will further his work into the “Control of T-Cell Functions by Neurotrophins in Skin Affected by Alopecia Areata.”

Neurotrophins are a family of structurally and functionally related polypeptides consisting of four proteins that induce a variety of biological reactions and which control cell proliferation, differentiation, survival, and apoptosis (programmed cell death). Significant data indicates that neurotrophins play an important role in the pathogenesis of autoimmune diseases and may suppress the immune response, providing protection in these disorders. Autoimmune disorders, including alopecia areata, are characterized by an increase of locally produced neurotrophins, which influence T-cell functions and the balance of cytokines (chemical messengers produced by cells) in the affected tissues. However, the functional significance of neurotrophins in the pathogenesis of alopecia areata is still unclear. This study aims to perform a detailed analysis of neurotrophin involvement in T-cell cytokine production as well as T-cell apoptosis in skin affected by alopecia areata. This work may lead to the use of neurotrophins in the treatment of alopecia areata and related hair growth disorders.

3. Angela Christiano, Ph.D., Columbia University, New York, New York, will receive funds to conduct a “Genome-Wide Search for Alopecia Areata Susceptibility Genes.”

Alopecia areata affects approximately 1.7 percent of the population and is estimated to account for 1 to 4 percent of dermatology consultations, but underestimation is likely. If the pathogenesis of alopecia areata were understood, then more effective therapies or prevention would be possible. With the advent of modern genomics, researchers are uniquely poised to increase knowledge surrounding the genetics of alopecia areata.

Several lines of evidence support the notion that alopecia areata is a polygenic, complex trait disorder including clustering in families, no clear pattern of Mendelian inheritance, a high population penetrance, concordance in twin studies, a Gaussian distribution (symmetrical bell-shaped curve) of phenotypes, and an increased risk to first-degree relatives. Genetic studies suggest that a permissive HLA status may potentiate the development of the alopecia areata phenotype; however, a systematic quest to identify the primary genetic mechanisms underlying this disorder has never before been undertaken.

Critical to the success of any genomics initiative is access to a large body of well-characterized and organized patient material which is now being created in the context of the recently funded NIH alopecia areata registry. Dr. Christiano will perform a genome-wide search for linkage from sibling pairs enrolled in the registry, as well as others previously collected. This search for genes underlying alopecia areata will utilize linkage analysis, including the affected sib pair method, in which no assumptions are made on mode of inheritance of the trait. Her laboratory will collect 200 sets of sibling pairs with alopecia areata, with as early an age of onset and extreme disease severity as possible, as well as their parents. The sibling pairs will be genotyped using markers covering the entire genome for the identification of candidate susceptibility loci, and linkage analysis will be performed. The goal of this study is to pinpoint candidate genes for alopecia areata and provide an understanding of the interactions of these genes with each other and with other variables such as the immune system and environmental triggers, and ultimately reveal rational therapeutic targets.

4. George Cotsarelis, M.D., University of Pennsylvania School of Medicine, Philadelphia, will further his research into “Gene Therapy for Alopecia.”

Dr. Cotsarelis has previously demonstrated that foreign genes can be introduced into human hair follicles by topically applying DNA in a mixture of fatty particles called liposomes. To study human hair follicles, his laboratory developed a model whereby a piece of human scalp containing about 500 follicles was transplanted onto immunodeficient mice. Using this model, he was able to demonstrate that hair follicles can only take up DNA when they are just entering the anagen (growth) stage. He was then able to introduce DNA into about 10 percent of the hair follicles in the graft after two weeks of treatment.

Anagen onset is a critical time because the characteristics of the new hair follicle are established, and in alopecia areata, anagen onset appears to trigger an attack by the immune system that prevents the follicle from completing its regeneration. One goal of the new research project is to demonstrate that the proteins encoded by this DNA can alter the characteristics of the hair follicle. To accomplish this, an array of genes will be introduced into the follicle, based on the likelihood that these genes will alter hair follicle biology even if they are only transiently present. Dr. Cotsarelis plans to target two of the major cell populations in the follicle that are likely to play a role in alopecia areata–matrix keratinocytes that produce the hair and pigment producing melanocytes. Eventually he hopes to introduce genes that protect these cells from the immune attacks in alopecia areata. Other goals include increasing the production of the gene product made by the hair cells and developing ways to permanently incorporate the DNA into the hair follicles. Overall, these studies are important steps toward the goal of developing gene therapy treatments for alopecia areata.

5. Stephen B. Harrap, M.D., and Justine A. Ellis, M.D., both at the University of Melbourne, Australia, and Rodney Sinclair, M.D., St. Vincent’s Hospital, Fitzroy, Victoria, Australia, will receive funds to investigate “The Androgen Receptor (AR) Gene and Alopecia.”

The loss of hair quite often has a genetic explanation, and this is certainly true in the common form of male pattern baldness. Dr. Harrap’s laboratory has recently discovered the involvement of a gene known as AR that controls the actions of the male sex hormone testosterone. There is evidence that genes also determine the likelihood and severity of alopecia areata. This study aims to find the exact mutation in the AR gene that contributes to hair loss and understand how this influences hair growth. In addition, the study will also determine whether the specific AR gene mutation is also associated with susceptibility to alopecia areata. This work will provide information about the basic biology of hair growth that is relevant to hair loss conditions including alopecia areata.

6. Joseph A. Rothnagel, Ph.D., University of Queensland, Brisbane, Australia, will investigate “The Role of Frizzled-3 in Hair Follicle Development.”

The making of a hair follicle requires a series of signals to be sent and received by the cells destined to become the new follicle. Failure to send or receive these signals can result in a lack of hair formation, hair loss, or in the development of certain cancers. The Wnt family of proteins mediates a fundamentally important signal in follicle development. Receptor proteins called “Frizzled” that lie on the cell surface receive the Wnt signal. About ten different Frizzled proteins have been identified and each one is thought to receive a specific Wnt signal. This study will examine the role of one of these Frizzled proteins (Frizzled-3) in hair follicle development by creating transgenic mice that lack this protein. These mice may mimic certain human hair disorders and thereby help identify the cause of those disorders and provide insights for the development of novel treatments.

7. Jerry Shapiro, M.D., Harvey Lui, M.D. and Liren Tang, Ph.D., all at the University of British Columbia in Vancouver, Canada, will conduct a study entitled “Gene Expression Profiling Mediated by Anthralin in Alopecia Areata Affected DEBR Rats.”

A variety of therapies have been tested in alopecia areata, but none of these treatments have been consistent in their efficacy and many have undesirable side effects. Successful therapies in valid animal models provide a tool to work out the precise mechanisms of treatment. Among the therapeutic agents tested in Dr. Shapiro’s lab, anthralin has been found to be one of the most effective reagents in stimulating hair regrowth in rats affected by alopecia areata. This study aims to bring a detailed and systematic gene analysis approach to the understanding of hair growth by therapeutic drugs in alopecia areata using the Dundee Experimental Bald Rat as a model. Once the therapeutic actions are understood at the molecular levels, more specifically targeted approaches for alopecia areata treatment can be developed in the future.

8. John P. Sundberg, Ph.D., DVM, (pictured) and Gregory Cox, Ph.D., both at The Jackson Laboratory, Bar Harbor, Maine, will receive funds to investigate “The Role of H2 (Histocompatibility Antigens) in C3H/HeJ Mouse Alopecia Areata.”

Prior work by Dr. Sundberg and others has led to the characterization of a mouse model for alopecia areata that closely resembles the human disease, and he has partially completed defining the locations of genes that affect the disease. Human alopecia areata has been linked to the major histocompatibility genes known as the HLA region, and specific areas within this region are associated with the different types of alopecia areata. Histocompatibility genes are important in organ transplants and determine whether or not a patient can accept an organ. Not surprisingly, these genes also modulate inflammatory and autoimmune diseases.

Dr. Sundberg’s mouse genome screening studies have previously identified four areas that are linked with alopecia areata. The most important locus is where the equivalent human genes associated with alopecia areata are located. This finding alone provides major support for the significance and value of the mouse model, in addition to the medical similarities and identical responses to treatments between these mice and human patients. His study will narrow the genetic interval to limit the number of potential genes causing or associated with alopecia areata, as well as take advantage of the unique mouse resource at The Jackson Laboratory to verify that these genes really play a role in alopecia areata. As these studies cannot be done in humans, they will provide powerful tools to define the mechanisms of alopecia areata.