Barbara Honecker (Hamburg / DE), Valentin Bärreiter (Hamburg / DE), Dr. Nahla Galal Metwally (Hamburg / DE), Dr. Katharina Höhn (Hamburg / DE), Karel Harant (Prague / CZ), Dr. Dániel Cadar (Hamburg / DE), Balázs Horváth (Hamburg / DE), Dr. Marco Er-Lukowiak (Hamburg / DE), Prof. Dr. Hanna Lotter (Hamburg / DE), Prof. Dr. Iris Bruchhaus (Hamburg / DE)
Abstract text
The protozoan parasite Entamoeba histolytica is the causative agent of amebiasis. While 90 % of intestinal infections remain asymptomatic, 10 % result in invasive disease. In some cases, parasites can invade the mucosa and migrate to the liver via the bloodstream, where amebic liver abscesses (ALAs) are formed. ALAs are deadly to humans if left untreated. Interestingly, ALA formation occurs more frequently in men compared with women. Onset of invasive disease is the result of parasite pathogenicity factors on the one hand and an overshooting immune response involving infiltrating monocytes and neutrophils on the other. To gain a better understanding of the interaction between parasite and host immune system, we investigate extracellular vesicles (EVs) as putative modulators of the immune response.
EVs were isolated from the supernatant of E. histolytica cultures using an ultracentrifugation-based approach. Biological characterization of the EVs was performed by proteomics, miRNA sequencing, nanoparticle tracking analysis and transmission electron microscopy. Two clonal cell lines differing in their pathogenicity were used for EV isolation. Analysis of the EV cargo revealed considerable differences between the two cell lines that might be relevant in the context of pathogenicity.
Analysis of putative immunostimulatory properties of these EVs was performed in vitro on primary murine monocytes and neutrophils from both male and female mice. RNASeq, flow cytometry and cytokine profiling were implemented to characterize the immune cell response. Stimulation of primary immune cells with EVs of both cell lines resulted in increased expression of activation markers on the cell surface and an increased secretion of pro-inflammatory cytokines, both in male- and female-derived cells. Regulation of genes involved in immune response was also observed using RNASeq. Taken together, these data suggest an involvement of EVs in the host immune response to E. histolytica infection.