Transcriptomics analysis highlights potential ways in human pathogenesis in Leishmania braziliensis infected with the viral endosymbiont LRV1

Leishmania (Viannia) braziliensis is a parasite prevalent in Brazil and associated with tegumentary leishmaniasis (TL), including cutaneous (CL) and mucosal (ML) forms. The mechanisms of pathogenesis of TL are not fully understood, including some factors related to the host and parasite interaction in response to infection, and especially about Leishmania RNA Virus 1 (LRV1), an endosymbiont virus parasitizing Leishmania species, particularly triggers ML. Molecular approaches are usually applied to compare situations and to understand these interactions. Here, microarray analysis identified 162 differentially expressed genes in LbLRV1+ vs. LbLRV1- infection, with 126 upregulated genes related to IFN signaling, OAS/RNAse L, vitamin D3, and RIG-I type receptors. Additionally, 36 down-regulated genes were observed. Then, two validation assays were performed to confirm these results (RT-qPCR and Cytometric Bead Array). The main results comprise the differential gene expression in cells infected with LbLRV1+ compared to LbLRV1- and control, with overexpression of various genes in LbLRV1+ cells. Cytokine levels showed no significant differences between LbLRV1+ and LbLRV1-. This study highlighted the activation of the OAS/RNase L signaling pathway and the non-genomic actions of vitamin D3 in LbLRV1+ infection compared to LbLRV1- and control. This research contributes to our understanding of the immune response and molecular pathways involved in Leishmania infections, particularly in the presence of LRV1. We used microarrays to detail the global gene expression program underlying infection of human mnocyte-derived macrophages with LbLRV1-, LbLRV1+ and identified distinct classes of genes upregulated during this process. Comparison of gene expression levels in human macrophages after infection with LbLRV1+ and LbLRV1- in relation to uninfected human macrophages. Samples from three donors were selected to obtain human peripheral blood mononuclear cells (PBMCs). PBMCs from each donor were divided into three sets of cell culture experiments for differentiation into macrophages. The first group consisted of cultures maintained with infection by a LbLRV1+ strain and the second group was maintained with infection by a LbLRV1- strain. As a control for the experiment, a third group of cell cultures was maintained without infection. Gene expression levels were evaluated using microarray analysis.