Ongoing Research Projects
Research in the Le Poole Lab is focused on immunotherapy the etiology and treatment of vitiligo, melanoma, and lymphangioleiomyomatosis (LAM) as well as tuberous sclerosis complex (TSC). Specifically, the objective is to design immunotherapeutics to treat these conditions. This is made possible by the interesting observation that each of these conditions shares some common target molecules suitable for treatment by vaccines. In the autoimmune condition vitiligo, the goal is to reduce the immune response that affects the livelihood of melanocytes, responsible for generating pigment in the skin. In turn, the immune response that develops in vitiligo patients provides a directive for how to target tumors. Likewise, the understanding that heat shock proteins are overexpressed in tumors in response to hypoxic stress has provided guidelines for a different approach towards autoimmune disease.
Currently ongoing projects in the lab with translational implications include the analysis and cloning of T cell receptors responsible for progressive depigmentation; studies of phenolic compounds that can selectively eliminate pigmented cells; differential expression of ganglioside D3 and immunotherapeutics to target this molecule in TSC; and the use of a modified heat shock protein (HSP70iQ435A) to treat vitiligo and other side effects of immunotherapy in melanoma. We compare and contrast the immune responses that can be achieved in tumor patients to those that naturally occur in patients with autoimmune vitiligo, with the ultimate goal of deciphering the factors that separate anti-tumor immunity from autoimmunity.
Painting in broad strokes, four projects are currently active in the lab, namely 1) Bleaching/melanoma chemoprevention; 2) Immunotherapy for lymphangioleiomyomatosis and Tuberous Sclerosis complex; 3) Targeting HSP70 to combat autoimmune side effects of immunotherapy and 4) Modulating Treg activity in autoimmune and anti-tumor responses.
Project 1 focuses on the development of a chemopreventive approach towards melanoma, where patients are treated with skin bleaching agents that eliminate melanocytes from the skin. The concept carries similarity to ‘elective surgery’ available for some other cancers. This strategy is further supported by the immune response that is indirectly elicited by dying melanocytes targeted by topically applied bleaching phenols. We have contributed to elucidating the mechanism by which phenolic agents can induce melanocyte death, expanded the arsenal of reagents to include those which specifically target the stem cell population and studied the immune response that follows. We have also initiated nanoparticle-based applications to facilitate the therapeutic translation of this strategy in vivo.
Project 2 addresses the pivotal role of HSP70i in driving autoimmune responses. This stress protein is included as a component of some anti-tumor vaccines based on its chaperone and adjuvant functions. With HSP70i as a driving force behind immune activation, halting its function can interfere with ongoing or newly initiated autoimmunity. We are looking into variants of HSP70i that interfere with autoimmunity while leaving anti-tumor responses intact. We initiated further safety and efficacy testing in models of vitiligo and melanoma as well as further research into the specific mechanisms by which variant HSP70i can support therapeutic objectives in vitiligo and melanoma.
Project 3 tests mean restoring tolerance in newly developed mouse models of autoimmune vitiligo. Contrary to the existing problem of overzealous regulatory responses that interfere with anti-tumor immunity, patients with autoimmune disease activity generally lack effective regulatory responses. So whereas anti-CD25 therapy to deplete Tregs is popular as a pretreatment for patients undergoing anti-tumor immunotherapy, the opposite holds true in autoimmune disease. We propose to manipulate Treg homing in particular, and recently demonstrated elevated CCR4 expression in circulating Treg from melanoma patients whereas its ligand is highly expressed in tumors; the opposite holds true in vitiligo. The Vitesse model of vitiligo is developed using a human T cell receptor from melanoma infiltrating T cells and expressing it in matched HLA-transgenics on a background of pigmented skin. T cells adoptively transferred into tumor-bearing- immunodeficient recipients are capable of keeping the tumors in check. The high-affinity T cell receptor is expressed on CD8 and CD4+ T cell subsets as well as on T cells lacking either co-receptor, allowing us to study their activity in different settings, including Tregs.
Project 4 focuses on the development of an immunotherapeutic vaccine suitable for patients with lymphangioleiomyomatosis (LAM). This devastating disease involves the development of slow-growing tumors in the lungs of female patients with mutations in TSC1 or TSC2. As tumor cells of smooth muscle cell origin transdifferentiate to express melanoma associated antigens, we propose to target melanosomal antigens using T cell receptor transgenic, autologous T cells. Alternatively, we can target the GD3 glycosphingolipid overexpressed in tumor cells by a novel therapeutic strategy to enhance NKT cell activity or by transgenic T cells in efforts to keep the tumors in check.