Deep Sequencing of Guinea Pig (Cavia Porcellus) Lung Small RNAs Reveals Differential Expression of microRNAs between Non-infected and BCG-Infected Lungs

Abstract

\n Background: Pulmonary tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) infection remains a major public health burden worldwide. It has been well documented that a group of small noncoding RNAs, microRNAs (miRNAs) are involved in the development and pathogenesis many diseases, including the TB. Guinea pigs are considered as one of the best animal models for biomedical research in TB, the potential roles of miRNAs in the innate immune regulation of guinea pig lung against Mtb infection are not well understood. Methods: In this study, we investigated the differential expression of miRNA profiles between the un-infected lungs and Mycobacterium bovis bacillus Calmette-Guérin (BCG)-infected lungs of guinea pigs via deep sequencing and bioinformatics analysis. Results: A total of 2508 miRNAs were identified, among them 1187 were conserved miRNAs and 56 were novel miRNAs in the uninfected lungs, and 1202 were identified as conserved miRNAs and 63 were novel miRNAs in the BCG-infected lungs. Interestingly, comparison analysis further identified 902 co-expressed miRNAs and 585 distinct miRNAs between these two groups. Of the 15 most abundantly conserved miRNAs in guinea pig lungs, which belong to 7 miRNA families, including miR23, miR29, miR145, miR320, miR378, miR451, and miR423. 13 of these 15 most abundant miRNAs were significantly downregulated and 2 of them were significantly upregulated in the BCG-infected lungs. Individually, miRNA Let-7f-5p, let-7f, let-7-5p and let-7b-5p were the most abundant in both profiles of the non-infected and BCG-infected guinea pig lungs. The predicted target genes of specific miRNAs found in guinea pig lungs were involved in regulation signaling pathways related to immune responses, including Toll-like receptors (TLRs), nuclear factor (NF)-kappa B, Wnt, mitogen-activated protein kinase (MAPK), and transforming growth factor (TGF)-beta signaling, as well as related to autophagy signaling mTOR and apoptotic molecule p53. Conclusions: These data of comprehensive analysis of miRNA transcriptome demonstrated the differential expression profiles of miRNAs during M. tuberculosis infection of guinea pig lungs. These results could facilitate the future exploitation of the roles of miRNAs in regulation of immune responses to M. tuberculosis infection using the guinea pig model.