Abstract
BackgroundTriatomines are blood-sucking vectors of Trypanosoma cruzi, the causative agent of Chagas disease. During feeding, triatomines surpass the skin host response through biomolecules present in their saliva. Dendritic cells (DCs) play a crucial role in the induction of the protection to aggressive agents, including blood-sucking arthropods. Here, we evaluated if salivary components of triatomines from different genera evade the host immunity by modulating the biology and the function of LPS- or T. cruzi-stimulated DCs.MethodsSaliva of Panstrongylus lignarius, Meccus pallidipennis, Triatoma lecticularia and Rhodnius prolixus were obtained by dissection of salivary glands and the DCs were obtained from the differentiation of mouse bone marrow precursors.ResultsThe differentiation of DCs was inhibited by saliva of all species tested. Saliva differentially inhibited the expression of MHC-II, CD40, CD80 and CD86 in LPS-matured DCs. Except for the saliva of R. prolixus, which induced IL-6 cytokine production, TNF-α, IL-12 and IL-6 were inhibited by the saliva of the other three tested species and IL-10 was increased in all of them. Saliva per se, also induced the production of IL-12, IL-6 and IL-10. Only the saliva of R. prolixus induced DCs apoptosis. The presence of PGE2 was not detected in the saliva of the four triatomines studied. Finally, T. cruzi invasion on DCs is enhanced by the presence of the triatomine saliva.ConclusionsThese results demonstrate that saliva from different triatomine species exhibit immunomodulatory effects on LPS and T. cruzi-stimulated DCs. These effects could be related to hematophagy and transmission of T. cruzi during feeding.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1890-x) contains supplementary material, which is available to authorized users.
Highlights
Triatomines are blood-sucking vectors of Trypanosoma cruzi, the causative agent of Chagas disease
It is noteworthy that the expression of MHC-II, CD40 and CD86 molecules was inhibited by saliva during differentiation of the Dendritic cells (DCs)
The MHC-II molecule was inhibited by saliva of P. lignarius, R. prolixus and T. lecticularia, CD40 was inhibited by saliva of P. lignarius, M. pallidipennis and T. lecticularia, and the CD86 was inhibited by the saliva of R. prolixus
Summary
Triatomines are blood-sucking vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Triatomines and other arthropod vectors trigger a series of events leading to modulation of immune and hemostatic responses of their hosts For this purpose, the saliva of these arthropods is released directly into the blood vessels and the surrounding tissues [1, 2] and contains an arsenal of molecules with antihemostatic and immune-modulatory activities [3, 4]. It has been shown that Rhodnius prolixus is capable of producing a class of histamine-binding proteins called nitrophorins This seems to be very important during blood-feeding, since the release of histamine by basophils and mast cells can induce inflammatory reaction with increased vascular permeability, plasma exudation and itching induction in the bite site [9,10,11]. More recently it has been shown that R. prolixus can secrete lysophosphatidylcholine (LPC), a lipid molecule present in saliva that may play a role in modulating macrophage and facilitating the transmission of T. cruzi to their hosts [12, 13]
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