MicroRNA expression signatures in lungs of mice infected with Mycobacterium tuberculosis

Tuberculosis (TB) is a major public health concern worldwide; however the factors that account for resistance or susceptibility to disease are not completely understood. Although some studies suggest that the differential expression of miRNAs in peripheral blood of TB patients could be useful as biomarkers of active disease, their involvement during the inflammatory process in lungs of infected individuals is unknown. Here, we evaluated the global expression of miRNAs in the lungs of mice experimentally infected with Mycobacterium tuberculosis on 30 and 60 days post-infection. We observed that several miRNAs were differentially expressed compared to uninfected mice. Furthermore, we verified that the expression of miR-135b, miR-21, miR-155, miR-146a, and miR-146b was significantly altered in distinct leukocyte subsets isolated from lungs of infected mice, while genes potentially targeted by those miRNAs were associated with a diversity of immune related molecular pathways. Importantly, we validated the inhibition of Pellino 1 expression by miR-135b in vitro. Overall, this study contributes to the understanding of the dynamics of miRNA expression in lungs during experimental TB and adds further perspectives into the role of miRNAs on the regulation of immune processes such as leukocyte activation.