miRNA-146b Targets TRAF6 and Inhibits LTA-Induced Inflammation of Bovine Mammary Epithelial Cells

Mastitis is an inflammatory disease of mammary tissue that impairs milk production and quality, thereby seriously threatening the economic viability of dairy farms. miRNAs, such as miR-146b, are emerging as new candidates for anti-inflammatory therapy, and their activity modulation may provide a basis for controlling inflammation. However, the exact role and underlying mechanisms of miR-146b in bovine mastitis and associated inflammatory pathways in bovine mammary epithelial cells are still unclear. To clarify this, we established an in vitro model by stimulating MAC-T cells with Lipoteichoic acid and investigated the miR-146b-associated molecular pathways. The data from this study showed increased miR-146b expression after LTA stimulation. Then, the dual-luciferase reporter assay identified TRAF6 as a genuine target of miR-146b. Overexpression of miR-146b repressed the TRAF6 level and NF-κB pathway activation. Consequently, the production and secretion of major pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6, were significantly repressed, which could be indicative of inhibition of the inflammation in the cell model. Meanwhile, knockdown of miR-146b abolished such benefits. Based on these findings, it is reasonable to conclude that miR-146b mitigates LTA-induced inflammatory responses in bovine mammary epithelial cells by directly targeting TRAF6 and downstream NF-κB signaling. The present study identifies the functional role of miR-146b in the regulation of inflammation in MAC-T cells and highlights its potential as a target in mastitis intervention.