MicroRNAs are small non-coding RNAs that regulate cellular processes by the post-transcriptional regulation of gene expression, including immune responses. The shift in the miRNA profiling of murine macrophages infected with Leishmania amazonensis can change inflammatory response and metabolism. L-arginine availability and its conversion into nitric oxide by nitric oxide synthase 2 (Nos2) or ornithine (a polyamine precursor) by arginase 1/2 regulate macrophage microbicidal activity. This work aimed to evaluate the function of miR-294, miR-301b, and miR-410 during early C57BL/6 bone marrow-derived macrophage infection with L. amazonensis. We observed an upregulation of miR-294 and miR-410 at 4 h of infection, but the levels of miR-301b were not modified. This profile was not observed in LPS-stimulated macrophages. We also observed decreased levels of those miRNAs target genes during infection, such as Cationic amino acid transporters 1 (Cat1/Slc7a1), Cat2/Slc7a22 and Nos2; genes were upregulated in LPS stimuli. The functional inhibition of miR-294 led to the upregulation of Cat2 and Tnfa and the dysregulation of Nos2, while miR-410 increased Cat1 levels. miR-294 inhibition reduced the number of amastigotes per infected macrophage, showing a reduction in the parasite growth inside the macrophage. These data identified miR-294 and miR-410 biomarkers for a potential regulator in the inflammatory profiles of microphages mediated by L. amazonensis infection. This research provides novel insights into immune dysfunction contributing to infection outcomes and suggests the use of the antagomiRs/inhibitors of miR-294 and miR-410 as new therapeutic strategies to modulate inflammation and to decrease parasitism.
Keywords: Cat2/Slc7a2; Leishmania; Tnfa; macrophage; microRNA; nitric oxide synthase 2.