RNA-seq reveals the role of miR-223 in alleviating inflammation of bovine mammary epithelial cells.

Bovine mammary epithelial cells (bMECs) are involved in the early defense against the invasion of intramammary pathogens and are essential for the health of bovine mammary gland. MicroRNA (MiRNA) is a key factor that regulates cell state and physiological function. In the present study, the transcriptome profiles of miR-223 inhibitor transfection group (miR-223_Inhibitor) and negative control inhibitor transfection group (NC_Inhibitor) within bMECs were detected via the RNA sequencing (RNA-seq) platform. Based on these experiments, the differentially expressed mRNAs (DE-mRNAs) of the miR-223_Inhibitor transfection group were screened, and the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional analyses of DE-mRNAs were performed. The results revealed that compared with the NC_Inhibitor, 224 differentially expressed genes (DEGs) were identified in the miR-223_Inhibitor, including 184 upregulated and 40 downregulated genes. The functional annotation of the above DEGs indicated that some of these genes are involved in the immune response generated by extracellular substance stimulation, regulation of the activity of cytokines and chemokines, and the immune signaling pathways of NF-κB and TNF. Meanwhile, miR-223_inhibitor upregulated the immune key genes IRF1 and NFκBIA, cytokines IL-6 and IL-24, as well as chemokines CXCL3, CXCL5, and CCR6, triggering a signaling cascade response that exacerbated inflammation in bMECs. These results suggested that miR-223 plays an important role in inhibiting the inflammatory response and maintaining the stability of bMECs, and is a potential target for treating mastitis in dairy cows.