Research Opps

Training Grant in Dermatological Research Supported by NIH (20 years of continuous funding):

The purpose of the program is to provide opportunities to young scientists and students in the field of dermatology. The need for scientists interested in biochemical, biological and pathological aspects of the skin is overwhelming. Our interest is to recruit trainees at the pre-doctoral and post-doctoral level. Primary emphasis will be on research training and, while supported by this training grant, the trainees will be expected to devote essentially their full time to develop scholarly investigative skills. Training is offered in the following areas: cutaneous autoimmunity, experimental immunopathology, cellular immunity, B and T cell biology, keratinocyte biology, protein biochemistry, molecular biology and dermatoepidemiology. Within the Department, Drs. Diaz, Liu, and Rubenstein maintain active NIH funded research activities; UNC faculty from departments other than Dermatology also serve as mentors for trainees. Dr. Stephen Clarke, Professor of Microbiology and Immunology at UNC, and Dr. Diaz are currently jointly supervising the research project of an M.D./Ph.D. student supported by this grant.

Individuals interested in pursuing careers in dermatological research will be recruited with the understanding that they will be fulltime trainees for the duration of the fellowship and that they are fully aware of pay back commitments.

Faculty:

Luis A. Diaz, M.D. (Department of Dermatology, UNC)
Ning Li, Ph.D. (Department of Dermatology, UNC)
Zhi Liu, Ph.D. (Department of Dermatology, UNC)
David Rubenstein, M.D., Ph.D., (Department of Dermatology, UNC)
Stephen Clark Ph.D., Department of Immunology and Microbiology, UNC
Robert Millikan, Ph.D., Department of Epidemiology, UNC

Individual Research Projects

Immunological and Epidemiological Studies in Endemic Pemphigus Foliceus: These studies are supported by an NIH RO1 grant:. The studies describe a series of protocols aimed at disclosing the etiology of Brazilian pemphigus foliaceus or Fogo Selvagem (FS). FS is a human autoimmune disease mediated by pathogenic autoantibodies that are produced by immunogenetically predisposed individuals living in certain rural areas of Brazil. The epidemiology of FS points toward an, as yet unknown, environmental antigen as the trigger of the disease. The antigenic mimicry model predicts that desmoglein-1 (dsg1) harbors T and/or B cell epitopes that cross-react with the environmental agent that precipitates the disease. In previous years, we identified a new FS focus with a unique set of environmental, genetic and cultural characteristics that make it an ideal population on which to focus our etiologic studies. This community, the Limao Verde Reservation in central Brazil, is composed of approximately 1,200 members of the Terena Indian tribe. Geographic, familial and temporal clustering patterns have been detected among the 28 FS cases on this reservation, and the disease was found to be associated with HLA-DRB1*0404, 1402 & 1406 haplotypes (RR=14). In contrast, other Terena reservations in the region show very few or no documented FS cases.

Aim 1 of this grant includes a series of case control epidemiological studies designed to further define genetic and environmental risk factors of the disease. Aim 2 investigates the cellular and molecular regulatory mechanisms involved in the pathogenic autoimmune response in FS. Finally, Aim 3 represents a highly focused immunological investigation of potential etiologic agents of FS. Our studies on salivary gland antigens from Simulium nigrimanum and other hematophagous vectors will be tested as a source of antigens that may precipitate FS.

Faculty:

Luis A. Diaz, M.D. (Department of Dermatology, UNC)
Robert Millikan, Ph.D., Department of Epidemiology, UNC
Zhi Liu, Ph.D. (Department of Dermatology, UNC)
Ning Li, Ph.D. (Department of Dermatology, UNC)
Evandro Rivitti, M.D. (Dermatology, University of Sao Paulo)
Valeria Aoki, M.D. (Dermatology, University of Sao Paulo)
Gunter Hans, Jr. (University of Mato Grosso do Sul, Brazil)

Immunological Studies in Pemphigus Vulgaris and Pemphigus Foliceus: During the last 20 years this NIH funded project has supported several relevant studies on pemphigus vulgaris (PV), non-endemic pemphigus foliaceus (PF) and Bullous Pemphigoid (BP) that are summarized as follows: a) our laboratory pioneered the development of animals models of PV and PF by passive transfer of patients’ IgG, b) we have developed affinity-chromatography procedures to purify autoantibodies from PF, PV and BP sera, c) we have developed a highly sensitive and specific ELISA to detect PF, PV and BP autoantibodies using recombinant proteins, d) we have studied 6 Fogo Selvagem (FS) patients (Brazil) in the pre-clinical stage and several normal controls that exhibit moderate titers of anti-dsg1 IgG autoantibodies, predominantly IgG1. These autoantibodies increased several fold when FS was fully established and the predominant IgG isotype was IgG4, f) we have been able to clone antigen-specific T cells from peripheral blood of FS patients from this Indian Reservation. In addition, g) we mapped the hemidesmosome as the target of BP autoantibodies, h) we discovered and characterized the BP180 antigen as a component of hemidesmosomes, i) we developed the first animal model of BP by passive transfer of anti-BP antibodies.

In these studies we hypothesize that in FS anti-dsg1 autoantibodies of the IgG1 and IgG4 subclass may differ in their pathogenicity and epitope-specificity. To test this hypothesis we will isolate and study dsg1-specific IgG1 and IgG4 from FS sera, clone and sequence V genes from B cells of these patients by single cell RT-PCR. Similar studies will be performed with anti-dsg3 autoantibodies in PV. These studies may lead to new therapies for these serious cutaneous autoimmune diseases.

Faculty:

Luis A. Diaz, M.D. (Department of Dermatology, UNC)
Stephen Clark Ph.D., Department of Immunology and Microbiology, UNC
Zhi Liu, Ph.D. (Department of Dermatology, UNC)
Ning Li, Ph.D. (Department of Dermatology, UNC)

Characterization of Immunopathology of Bullous Pemphigoid: Bullous pemphigoid (BP) and herpes gestationis (HG) are autoimmune disorders that are characterized by the presence of sub-epidermal vesicles and anti-basement membrane zone (BMZ) autoantibodies. It has been postulated that the key pathogenic elements of these diseases include autoantibody reactivity to a BMZ antigen, complement activation, and the subsequent inflammatory reaction. The BP180 antigen is a component of the BMZ which contains a common antigenic domain recognized by both BP and HG autoantibodies. Our research group developed an animal model of BP and HG using tools developed by molecular genetic techniques. Rabbit antibodies were generated against a murine BP180 fusion protein containing the stretch homologous with the autoantibody-reactive region of the human antigen. Significantly, passive transfer of these rabbit antibodies into neonatal mice induced cutaneous blisters with all of the established immunopathological features of BP and HG. These results strongly suggested that anti-BP180 autoantibodies produced in BP and HG patients mediate the subepidermal blister formation characteristic of these diseases.

The major focus of the present studies is to further define the molecular and immunopathological mechanisms involved in subepidermal blistering using this mouse model. We will further dissect the mechanisms of recruitment and activation of inflammatory cells including neutrophils, eosinophils and mast cells (i.e., the role of cell adhesion molecules, cell surface receptors, and cytokines and chemokines). We will determine the role of proteinases and reactive free radicals released from these inflammatory cells in experimental BP and HG. We will also develop human BP180 transgenic mice to directly test pathogenic activity of autoantibodies from BP and HG patients’ sera. Finally, we will initiate preclinical trials to block tissue damage in experimental BP and HG. The results from these studies will have profound clinical implications in the care of patients with BP and HG.

Faculty:

Zhi Liu, Ph.D., Professor
Luis A. Diaz, M.D., Professor and Chairman

Regulation of Keratinocyte Adherens Junctions and Desmosomes: ?-catenin and plakoglobin are constituents of the adherens junction cell-cell adhesion complex. Plakoglobin also forms part of the desmosome cell-cell adhesion complex. In addition to functioning in cell-cell adhesion, ?-catenin and plakoglobin act downstream of frizzled cell surface receptors to mediate Wnt signaling. Human disease results from aberrant regulation of the adhesion and signaling functions of these proteins. For example, (1) ?-catenin's signaling function is constitutively activated in human cancers including colorectal carcinoma and melanoma and (2) desmogleins, constituents of the desmosome to which plakoglobin binds, are the target antigens for autoantibodies produced in the autoimmune blistering diseases pemphigus vulgaris and pemphigus foliaceus.

Our lab is interested in understanding (1) how cells regulate their ability to adhere to one another, (2) how cell-cell adhesion complexes might also function to transduce signals that “inform” the cell about the state of adhesion, a process known as signal transduction, and (3) the relationship of these regulatory events to human skin disease.

Current projects in the lab focus on the human proteins ?-catenin and plakoglobin, and the related fruit fly protein Armadillo. We have previously shown that tyrosine phosphorylation of human keratinocyte plakoglobin and ?-catenin reversibly regulates adherens junction complex formation and cell-cell adhesion. Currently, we are using this system to study transcriptional regulatory events that result from changes in the adherens junction structure. Our observations suggest a direct signaling pathway through the adherens junction.

Because PF and PV IgG bind to desmoglein cell-cell adhesion molecules and disrupt keratinocyte cell-cell adhesion, we are using these specific antibodies to study signal transduction initiated through changes in desmosome structure. Our initial observations suggest that binding of these antibodies to the extracellular domain of desmoglein activates intracellular signaling cascades. The relationship of these signaling events to the mechanism of blister formation is an active area of investigation. Using a wide variety of genetic, cell biology and protein chemistry techniques, we are elucidating the components of each of these signaling pathways and the relationship of deregulation to malignancy and to the mechanism of blister formation in PV and PF.

These studies are supported by an NIH RO1 grant.

Faculty:

David S. Rubenstein, M.D., Ph.D., Associate Professor
Peiqi Hu, M.D., Research Assistant Professor