Passive case detection and treatment constitute the principal, often the sole measure of control for cutaneous leishmaniasis (CL) in Central and South America yet first line therapies (pentavalent antimonials, pentamidine and miltefosine) are often ineffective (overall non response is of the order of 24% based on a recent meta analysis [1]) and poorly tolerated. Since pathogenesis of dermal leishmaniasis is mediated by the immune and inflammatory responses, resolution of disease and control of infection are intimately linked to the host response. Consequently, antileishmanial drugs alone are often insufficient to clinically resolve disease even in immunocompetent individuals, and furthermore, do not eliminate infection [2-6]. Although immune mechanisms underlying the outcome of infection differ among Leishmania species [7], non-healing phenotypes of infection by different species can be converted to healing phenotypes and vice versa by intervention of the host immune response [8-12]. In experimental models, a wide range of interventions (including deletion of T cell populations, neutralization or genetic depletion of cytokines that drive T cell differentiation, down regulate macrophage activation, or modulate T regulatory cell function) invert susceptibility and resistance. Importantly, these interventions have broadly targeted immune function rather than responses to specific parasite antigens. The feasibility of translating this experience with murine models to human leishmaniasis is supported by the clinical resolution of cutaneous and mucosal disease unresponsive to chemotherapy alone, by co-adjuvant immunotherapy [13-17]. However, neither the immunological basis of the healing response enabled by these interventions, the mechanisms involved nor the generalizability of any immunotherapeutic intervention (to different species of Leishmania or for the spectrum of clinical outcomes) has been determined. Local as well as systemic and combined therapies have recently been recommended as alternatives for New World cutaneous leishmaniasis by the WHO Expert Committee on Leishmaniasis. Risk/benefit considerations of the toxicity of current systemic treatment regimens, persistence of infection following treatment, and evidence of the effectiveness of various local therapies compelled the amplification of therapeutic options to include local and combined strategies. Such strategies may be optimized through innovative delivery of antileishmanial drugs and immunomodulators via nanoparticle technology. This project seeks to identify the immunologic bases of healing of cutaneous leishmaniasis caused by Leishmania Viannia species, and to discern the mechanisms of immunomodulation that together with chemotherapy, improve clinical outcome, reduce parasite burden and persistence, and preserve the effective life of antileishmanial drugs.

Public Health Relevance

Cutaneous leishmaniasis (CL) is a parasitic disease of global importance effecting 12 million people in 88 countries worldwide;current treatments involve drugs that are toxic, with severe side reactions. In Colombia and parts of South America, this disease is increasingly a disease of children. This project is focused on the development of effective topic treatment for CL through the targeted stimulation of the host immune response that should avoid toxicity and adverse side reactions.

National Institute of Health (NIH)
Research Project (R01)
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Immunity and Host Defense (IHD)
Program Officer
Wali, Tonu M
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Yale University
Public Health & Prev Medicine
Schools of Medicine
New Haven
United States
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Navas, Adriana; Vargas, Deninson Alejandro; Freudzon, Marina et al. (2014) Chronicity of dermal leishmaniasis caused by Leishmania panamensis is associated with parasite-mediated induction of chemokine gene expression. Infect Immun 82:2872-80
Gomez, Maria Adelaida; Navas, Adriana; Marquez, Ricardo et al. (2014) Leishmania panamensis infection and antimonial drugs modulate expression of macrophage drug transporters and metabolizing enzymes: impact on intracellular parasite survival. J Antimicrob Chemother 69:139-49
Rodriguez-Pinto, Daniel; Saravia, Nancy Gore; McMahon-Pratt, Diane (2014) CD4 T cell activation by B cells in human Leishmania (Viannia) infection. BMC Infect Dis 14:108
Ehrlich, Allison; Castilho, Tiago Moreno; Goldsmith-Pestana, Karen et al. (2014) The immunotherapeutic role of regulatory T cells in Leishmania (Viannia) panamensis infection. J Immunol 193:2961-70
Fernández, Olga Lucía; Diaz-Toro, Yira; Ovalle, Clemencia et al. (2014) Miltefosine and antimonial drug susceptibility of Leishmania Viannia species and populations in regions of high transmission in Colombia. PLoS Negl Trop Dis 8:e2871
Rodriguez-Pinto, Daniel; Navas, Adriana; Blanco, Victor Manuel et al. (2012) Regulatory T cells in the pathogenesis and healing of chronic human dermal leishmaniasis caused by Leishmania (Viannia) species. PLoS Negl Trop Dis 6:e1627