Immunotherapy and Immunochemotherapy in Visceral Leishmaniasis: Promising Treatments for this Neglected Disease

Abstract

Leishmaniasis has several clinical forms: self-healing or chronic cutaneous leishmaniasis or post-kala-azar dermal leishmaniasis; mucosal leishmaniasis; visceral leishmaniasis (VL), which is fatal if left untreated. The epidemiology and clinical features of VL vary greatly due to the interaction of multiple factors including parasite strains, vectors, host genetics, and the environment. Human immunodeficiency virus infection augments the severity of VL increasing the risk of developing active disease by 100–2320 times. An effective vaccine for humans is not yet available. Resistance to chemotherapy is a growing problem in many regions, and the costs associated with drug identification and development, make commercial production for leishmaniasis, unattractive. The toxicity of currently drugs, their long treatment course, and limited efficacy are significant concerns. For cutaneous disease, many studies have shown promising results with immunotherapy/immunochemotherapy, aimed to modulate and activate the immune response to obtain a therapeutic cure. Nowadays, the focus of many groups centers on treating canine VL by using vaccines and immunomodulators with or without chemotherapy. In human disease, the use of cytokines like interferon-γ associated with pentavalent antimonials demonstrated promising results in patients that did not respond to conventional treatment. In mice, immunomodulation based on monoclonal antibodies to remove endogenous immunosuppressive cytokines (interleukin-10) or block their receptors, antigen-pulsed syngeneic dendritic cells, or biological products like Pam3Cys (TLR ligand) has already been shown as a prospective treatment of the disease. This review addresses VL treatment, particularly immunotherapy and/or immunochemotherapy as an alternative to conventional drug treatment in experimental models, canine VL, and human disease.

DNA prime‐protein boost vaccine encoding HLA‐A2, HLA‐A24 and HLA‐DR1 restricted epitopes of CaNA2 against visceral leishmaniasis

“…In addition, after 2 months of infection, the IFN‐ γ level was not significantly different among the groups, indicating that the T helper type 1 (Th1) immune response in the mice was not strong. As control of VL depends on a successful cell‐mediated immune response in which IFN‐ γ and natural killer cells lead to stimulation of the microbicidal action mediated by NO, this result suggested that our vaccines were not ideal. However, we consider that this observation might also be caused by the dose and inoculation route.…”

CD8+ T cells in cutaneous leishmaniasis: the good, the bad, and the ugly

“…The parasite replicates in the spleen, liver and bone marrow, and in the absence of drug treatment the disease is fatal (9). …”

Leishmania vaccine development: exploiting the host–vector–parasite interface

“…In South Asia and East Africa, VL is anthroponotic and caused by L. donovani (10). In the Mediterranean region, and in Central and South America, the disease is zoonotic and caused by L. infantum (= L. chagasi ) where the main reservoir is dogs (11). Recently, cats and leporids have also been considered as possible alternative reservoirs of VL in certain foci in the Mediterranean region (12).…”