Dendritic Cells and Leishmania Infection: Adding Layers of Complexity to a Complex Disease

Abstract

Leishmaniasis is a group of neglected diseases whose clinical manifestations depend on factors from the host and the pathogen. It is an important public health problem worldwide caused by the protozoan parasite from the Leishmania genus. Cutaneous Leishmaniasis (CL) is the most frequent form of this disease transmitted by the bite of an infected sandfly into the host skin. The parasites can be uptook and/or recognized by macrophages, neutrophils, and/or dendritic cells (DCs). Initially, DCs were described to play a protective role in activating the immune response against Leishmania parasites. However, several reports showed a dichotomic role of DCs in modulating the host immune response to susceptibility or resistance in CL. In this review, we discuss (1) the interactions between DCs and parasites from different species of Leishmania and (2) the crosstalk of DCs and other cells during CL infection. The complexity of these interactions profoundly affects the adaptive immune response and, consequently, the disease outcome, especially from Leishmania species of the New World.

Figure 1

Interaction of DC with different leukocytes in the cutaneous leishmaniasis context. (a) shows the interaction among NK and infected DCs that leads to host immune protection and parasite killing through IFN-γ production during L. amazonensis [73] or L. major [74] infection. (b) shows the outcome induced by the increased production of IL-10 after the interaction between infected neutrophils (NΦ) with L. major [75] or L. mexicana [76] and DCs, leading to parasite persistence.