microRNA and Regulatory Networks of Human Macrophage During Leishmania major In Vitro Infection

Leishmania (L.) major modulates host microRNA (miR) expression to promote intracellular survival, yet the roles of specific miRs during early infection of human macrophages remain poorly defined. We investigated the dynamic regulation of miR-21-5p and miR-146a-5p in THP-1-derived macrophages infected with L. major over an early post-infection time course (3–48 h), alongside miR-30a-3p and miR-101-3p. Both miR-21-5p and miR-146a-5p were significantly upregulated during the early stages of infection (3–24 h) before declining by 48 h. Using antisense LNA inhibitors, we achieved independent single and dual silencing of both miRs, allowing us to dissect their functional contribution to host gene expression. In silico network analysis identified 887 shared and specific target genes, including NFKB1, MYC, STAT3, HIF1A, TNF, CXCL8, IL18, and XBP1. Silencing of miR-21-5p and miR-146a-5p at early time points relieved inhibitory control over several of these targets, notably increasing NF-κB, MYC, IL18 and XBP1 expression, and reducing TNF and sXBP1, consistent with their role as negative regulators of innate immune signaling. These findings identify miR-21-5p and miR-146a-5p as early, dynamic regulators of the human macrophage transcriptional response to L. major infection and identify their target genes as candidate biomarkers and therapeutic targets in cutaneous leishmaniasis.