Plasma lipoproteins in visceral leishmaniasis and their effect on Leishmania-infected macrophages

This work aimed at investigating the lipid profile of zoonotic visceral leishmaniasis (VL) patients' sera and the effect of lipoproteins on the in vitro production of tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, IL-10 and IL-12 by Leishmania infantum-infected and uninfected macrophages. Lipids were quantified in 26 VL patients' sera and 26 healthy controls from a VL endemic area. The patients' sera had higher triglyceride and very low density lipoprotein (VLDL) levels, and much lower apolipoprotein A1, total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) levels than the control sera. Lipoprotein fractions were obtained by ultracentrifugation of sera. The addition of LDL and HDL to Leishmania-infected and uninfected macrophages, in physiological concentrations, enhanced the production of IL-6 and IL-10, but not of IL-12. LDL stimulated the production of TNF-alpha only in infected macrophages, whereas HDL stimulated the production of lower amounts of TNF-alpha in both infected and uninfected macrophages. VLDL stimulated only the production of IL-10. It is proposed herein that LDL may influence the development of VL by promoting the production of TNF-alpha by infected macrophages. A decrease in plasma LDL in some VL patients (to 20 mg/mL or less); however, would tend to reduce the production of TNF-alpha and therefore to limit the development of immune-mediated pathology, not withstanding the fact that it would perhaps increase the permissiveness of macrophages to Leishmania growth.