Role of Toll-like receptors (TLRs) during infestation by Rhipicephalus sanguineus ticks.

• Grant number: 11/18813-2
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Effective date (Start): February 01, 2012
• Effective date (End): January 31, 2015
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Beatriz Rossetti Ferreira
• Grantee: Elen Anatriello
• Host Institution: Escola de Enfermagem de Ribeirão Preto (EERP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Ticks are hematophagous arthropods that parasitize vertebrate hosts and transmit a variety of infectious agents to domestic animals, wildlife and humans. In tick-host interface there is involvement of both the innate immune response and the acquired immune response of the host, which are modulated by inoculation of tick saliva. Among the mechanisms used by ticks to evade the protective response of their hosts, our group have shown that Rhipicephalus sanguineus infested with mice have a Th2 type immune response, and that the saliva of ticks can modulate the function of various immune cells, including macrophages, lymphocytes, and modulate the maturation, migration and function of dendritic cells (DCs) stimulated by ligands for Toll-like receptors (TLRs). We also observed that the saliva of R. sanguineus induces in vitro a high expression of TLR-2 receptor on the DCs surface. These results suggest that one mechanism by which the saliva of R. sanguineus modulates the host immune response possibly is through TLRs. The present work evaluates the role of tick infestation with R. sanguineus in the modulation of the immune response mediated by TLRs. For so, we will evaluate the expression of TLRs on DCs, T and B cells from the peripheral blood, spleen and skin of tick-infested mice. We will also analyze the response of these cells (activation, proliferation and cytokine production) to stimuli such as TLRs ligands. Knowing that the MyD88 signaling is critical for most TLRs, we will also evaluate the tick biological and reproductive parameters during an infestation on mice deficient in MyD88. These mice will also be evaluated for parameters of cellular and humoral immune response during the tick infestation. The findings will bring a new understanding of the role of the innate immune response receptors as modulators of host immune response during the success of the infestation, and contribute to new perspectives for the control of the ticks.Keywords: Tick, R. sanguineus; saliva; immune modulation; TLRs.