Abstract
BackgroundSand fly saliva contains potent and complex pharmacologic molecules that are able to modulate the host's hemostatic, inflammatory, and immune systems. In this study, we evaluated the effects of salivary gland sonicate (SGS) of Lutzomyia intermedia, the natural vector of Leishmania braziliensis, on monocytes obtained from the peripheral blood mononuclear cells (PBMC) of healthy volunteers. We investigated the effects of sand fly saliva on cytokine production and surface molecule expression of LPS-stimulated human monocytes uninfected or infected with L. braziliensis.ResultsPre-treatment of non-infected human monocytes with L. intermedia SGS followed by LPS-stimulation led to a significant decrease in IL-10 production accompanied by a significant increase in CD86, CD80, and HLA-DR expression. Pre-treatment with SGS followed by LPS stimulation and L. braziliensis infection led to a significant increase in TNF-α, IL-6, and IL-8 production without significant alterations in co-stimulatory molecule expression. However, pre-treatment with L. intermedia SGS did not result in significant changes in the infection rate of human monocytes.ConclusionOur data indicate that L. intermedia saliva is able to modulate monocyte response, and, although this modulation is dissociated from enhanced infection with L. braziliensis, it may be associated with successful parasitism.
Highlights
Sand fly saliva contains potent and complex pharmacologic molecules that are able to modulate the host's hemostatic, inflammatory, and immune systems
We have examined the effects of saliva from L. intermedia, the main vector of L. braziliensis in Brazil, on human monocytes stimulated with LPS and uninfected or infected with L. brazilienis
L. intermedia is the sand fly species responsible for the transmission of Leishmania braziliensis, the causative agent of cutaneous and mucosal leishmaniasis; we have investigated the effects of L. intermedia saliva on the host's immune response in terms of surface molecule expression and cytokine production
Summary
Sand fly saliva contains potent and complex pharmacologic molecules that are able to modulate the host's hemostatic, inflammatory, and immune systems. We investigated the effects of sand fly saliva on cytokine production and surface molecule expression of LPS-stimulated human monocytes uninfected or infected with L. braziliensis. Cutaneous leishmaniasis (CL) caused by Leishmania major is usually benign; infection of human hosts leads to the development of a localized cutaneous lesion that eventually heals, leading to the generation of life long-immunity. CL caused by L. braziliensis is distinguished from other leishmaniasis by its chronicity, latency, and tendency to metastasize in the human host [1]. In this disease, a single ulcer with elevated borders and a necrotic centre is frequently observed, and a chronic inflammatory response develops despite the paucity of parasites.
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