Chicken gga-miR-1306-5p targets Tollip and plays an important role in host response against Salmonella enteritidis infection

BACKGROUND: Increasing evidence indicates that microRNAs (miRNAs) are involved in inflammatory response and immune regulation following pathogen invasion. The purpose of this study was to elucidate the roles played by Gallus gallus microRNA-1306-5p (gga-miR-1306-5p) in host responses against potential invasion by Salmonella enteritidis (SE) in chickens and the underlying mechanisms. RESULTS: In present study, the expression levels of gga-miR-1306-5p were determined in both tissues and HD11 cells. The results showed that gga-miR-1306-5p was significantly increased following SE infection or lipopolysaccharide (LPS) stimulation. The dual luciferase reporter assay further validated that gga-miR-1306-5p targeted the Toll-interacting protein (Tollip), and thereby participated in the regulation of immune response against SE or LPS stimulation through binding with the 3′-untranslated region (3’UTR) of Tollip. Additionally, the expression of Tollip was significantly blocked by over-expressed gga-miR-1306-5p. The underlying mechanisms by which gga-miR-1306-5p modulated the production of pro-inflammatory cytokines were also investigated. Molecular biological assays demonstrated that overexpression of gga-miR-1306-5p promoted the production of pro-inflammatory mediators, including NF-κB, TNF-α, IL-6, and IL-1β, which produced effects similar to those of Tollip knockdown. CONCLUSIONS: Taken together, gga-miR-1306-5p induced by SE or LPS, regulates the immune response by inhibiting Tollip, which activates the production of inflammatory cytokines. This study has provided the first direct evidence that gga-miR-1306-5p targets Tollip, and is involved in the host response against SE.