Enhanced expression of Toll-like receptors 2 and 4, but not 9, in spleen tissue from patients with visceral leishmaniasis.

Toll-like receptor (TLR) signalling is involved in first-line defence against Leishmania parasites by triggering NF-κB activation and downstream production of proinflammatory cytokines. Experimental models of visceral leishmaniasis (VL) support a protective role for TLRs 2, 4 and 9 in host immune responses to Leishmania infection. There are limited data available on expression of these TLRs in human VL, particularly in sites of infection, such as the spleen. This study aimed to determine whether the expression of mRNA encoding the expression of TLRs 2, 4 and 9 was altered in VL and compare expression patterns in splenic biopsies and peripheral blood mononuclear cells.