Effect of AED7L2 Protein on the Modulation of the Vertebrate Host's Innate Immune Response

Insect vector-borne diseases account for approximately 17% of all infectious diseases worldwide, according to the World Health Organization. Although the insect’s role in infection is well-established, experimental models often overlook the impact of vector-derived molecules on the initial inflammatory response to transmitted pathogens. The saliva of hematophagous insects contains various pharmacological molecules, including proteins that subvert the host’s hemostatic mechanisms and modulate immune responses, recruiting leukocytes to the skin. Despite the importance of saliva and its proteins in establishing infection, the contributions of individual salivary proteins remain unclear. This project aims to evaluate the role of the D7L2 protein in modulating neutrophil and macrophage functions. D7, with a molecular weight of 37.01 kDa, is one of the most abundant proteins in Aedes aegypti saliva and binds to biogenic amines such as histamine and catecholamines. However, its effect on human innate immune cells is unknown. Neutrophils were purified by density gradient from the blood of healthy volunteers, incubated with varying concentrations of D7, and activated or not with lipopolysaccharide (LPS). PBMCs were also purified, with monocytes differentiated into macrophages, treated with D7, and infected with CHIKV. Our results show that D7 decreases the release of neutrophil extracellular traps without affecting reactive oxygen species (ROS) production, which was measured using DHR123, or leukocyte viability, assessed by LDH assay. Additionally, CHIKV does not induce extracellular traps or ROS in neutrophils. In macrophages, D7 reduces Chikungunya virus infection. The DNA content in the samples was quantified using PicoGreen. Future studies will examine D7's role in cytokine production, phagocytosis, and chemotaxis.