Abstract Ticks are notorious blood-sucking ectoparasites affecting both humans and animals, and serve as a unique vector of various deadly diseases. Here, we have shown the roles of the receptor for advanced glycation end-products (RAGE) during repeated infestations by the tick, Haemaphysalis longicornis using RAGE-/- mice. In primary infestation, a large blood pool developed which was flooded with numerous RBC, especially during the rapid feeding phase of the tick both in wild type (wt) and RAGE-/- mice. Very few inflammatory cells were detected around the zones of hemorrhage in the primary infestations. However, number of inflammatory cells gradually increased in the subsequent tick infestations and at the 3 rd infestations number of inflammatory cells reached to the highest level (350.3±16.8 cells/focus), and the site of attachment was totally occupied by the inflammatory cells in wild type (wt) mice whereas very few cells were detected at the ticks’ biting sites in RAGE-/- mice. RAGE was highly expressed in the 3 rd infestation in wt mice. In the 3 rd infestation, infiltration of innate lymphoid cells type 2 (ILC2s), expression of S100A8 and S100B significantly increased at the biting sites of ticks in wt, but not in RAGE -/- mice. Also, peripheral eosinophil counts significantly increased in wt but not in RAGE -/- mice. Taken together, our study revealed that RAGE-mediated inflammation and eosinophils played crucial roles in the tick induced inflammatory reactions.

Aim: Natural transmission of Trypanosoma cruzi occurs when infected hematophagous deposit feces contaminated with metacyclic trypomastigotes on injured skin or mucosa. To study the inflammatory response at the inoculation site, dissemination of parasites, Th cell subtypes at the local lymph nodes and myocarditis mice were exposed to Triatoma dimidiata naturally contaminated with Trypanosoma cruzi. Methods and results: Mice were intradermal inoculated with T. dimidiata feces containing metacyclic trypomastigotes or were previously immunized with feces without metacyclic trypomastigotes and analyzed from 15 minutes to 3 months after inoculation. Parasites remained at the inoculation site until 20 days after inoculation but disappeared early in pre-immunized mice that presented with edema and collagen fragmentation as early as 15 minutes after being challenged with metacyclic trypomastigotes. The Th2 subpopulation dominated in the first week in mice infected with feces containing metacyclic trypomastigotes, whereas Th1 and Th17 populations dominated in the challenged mice population. Similarly in heart tissue, intense myocarditis and remodeling, with faster clearance of amastigotes was observed in mice previously immunized with Triatoma dimidiata feces. Furthermore, immune cell-types, Th1 and Th17, predominated after 20 days post-infection in all experimental groups. Conclusions: Previous exposure with Triatoma dimidiata feces prior to infection with metacyclic trypomastigotes favors parasitic dissemination and early induction of Th1 and Th17 subpopulations with lower parasitism in heart tissue but does not ameliorate inflammation and tissue damage which is accompanied with Th1/Th17 and Treg profile.

Introduction: The T-cell subset (CD4+Tregs) play a significant role in immunoregulation, by active suppression of the immune system, through cell-to-cell contact and the secretion of IL10. The frequencies of these cell subpopulations were investigated in the mother. Methods: The study recruited 61 mothers out of this number, 31 mothers with plasmodium parasitized placentas and 30 mothers without plasmodium infection. Placental malaria positivity was determined by PCR and microscopy. Peripheral mononuclear cells (PBMCs) were isolated from peripheral blood, cultured in the presence of VAR2CSA antigen, and stained with antibodies (CD3, CD4, CD25, and IL-10), before cytometry analysis. Results: The CD4+CD25+ T cell frequencies were significantly higher in all the participants (p<0.0001), and comparable across gravida. These cell populations were similar when compared between primigravid and secumgravida mothers (p=0.77), and between multigravida and secumgravida mothers (p=0.84). Primigravid mothers with placental malaria had significantly higher frequencies of CD4+CD25+ T cell population (p=0.04). The frequencies of CD4+IL10 were significantly high in both primigravid and multigravid mothers who were placental malaria positive (p=0.03) and (p=0.04) respectively. Conclusion: Induced Tregs (CD4+IL10) cells could play a role in placental malaria susceptibility due to an increase in their populations in mothers with plasmodium-infected placentas.