Down-regulation of miR-18b-5p protects against splenic hemorrhagic shock by directly targeting HIF-1α/iNOS pathway.

Splenic hemorrhagic shock is a typical emergency in surgery, seriously threatening human beings' life. Emerging evidence shows that microRNAs (miRNAs) are closely related to inflammation and immunity in the body. However, the detailed effects and underlying mechanisms of miRNAs on the immune function of splenic hemorrhagic shock have not been revealed yet. In the present study, we construct the rat hemorrhagic shock model, and the rats are further cured with splenic blood transport clipping recanalization (SBTCR). MiR-18b-5p was highly expressed in the spleen of hemorrhagic shock rats detected by the qRT-PCR assay. Functionally, down-regulation of miR-18b-5p notably inhibited the levels of SOD1, iNOS and IL-6 in macrophages isolated from splenic tissues detected by qRT-PCR and ELISA assays. In addition, inhibition of miR-18b-5p significantly decreased the M1/M2 ratio of macrophages. Besides, knockdown of miR-18b-5p obviously reduced the Th1/Th2 ratio of CD4 T cells. Moreover, HIF-1α was predicted as a target gene of miR-18b-5p, which was further confirmed by dual-luciferase reporter assay, and HIF-1α was negatively associated with miR-18b-5p. Furthermore, overexpression of HIF-1α partially restored the effects of miR-18b-3p on inflammation and immunity in macrophages. Taken together, miR-18b-5p may be a novel therapeutic candidate target in splenic hemorrhagic shock treatment.