Zanatta, J. M.; Bahia, I. A. F.; Sousa, E. S. A. d.; Teixeira, C. A.; Kato, K. T.; Bento, C. A.; Acuna, S. M.; Lima, M. R. D.; Silvestre, R.; Fonseca, D. L. M.; Muxel, S. M.

MicroRNAs (miRNAs) are small noncoding RNAs that regulate immune responses and are potential biomarkers and therapeutic targets in complex diseases. Leishmania amazonensis (L. amazonensis), an intracellular protozoan parasite, causes cutaneous leishmaniasis by replicating inside macrophages and compromises host immunity. In this context, miRNAs act as post-transcriptional regulators of inflammation during infection. Here, we analyzed the function of miR-721 in macrophages during L. amazonensis infection by integrating in silico target prediction with RNA-seq data from resistant C57BL/6 and susceptible BALB/c mice. miR-721 was induced in infected macrophages, but not in LPS-stimulated cells. Specifically, miR-721 is predicted to target the 3'UTRs of Tnf and Irf1 to suppress the inflammatory response. Integrated analyses revealed the TNF-IRF1 axis as a key miR-721-associated network, with predicted targeting of Tnf and Irf1. Inhibition of miR-721 restored their expression and reduced parasite burden. Additionally, miR-721 regulated downstream genes such as Serpine1, Csf1, Cd69, and Maf. While C57BL/6 macrophages showed robust TNF-IRF1 activation, BALB/c cells exhibited impaired responses, favoring parasite persistence. These findings indicate that Leishmania induces miR-721 to suppress host immunity.