Inhibition of miR-181a attenuates sepsis-induced inflammation and apoptosis by activating Nrf2 and inhibiting NF-κB pathways via targeting SIRT1.

Sepsis is caused by microbial infection with high mortality worldwide, and characterized by multiple organ dysfunction and systemic inflammatory response. Previous study shows that miR-181a level is increased during sepsis; however, the mechanism is still unknown. Therefore, to identify the role of miR-181a, lipopolysaccharide (LPS) was used to stimulate mouse peritoneal macrophages. The expressions of miR-181a and SIRT1 were identified by QRT-PCR, the levels of SIRT1, Nrf2, p-P65, Bcl-2 and Bax were detected by western blotting, the inflammatory cytokines TNF-α, IL-6 and IL-1β were detected by ELISA, and the apoptosis was measured by flow cytometry. Bioinformatics and dual luciferase assay were used to unveil the binding sites and the targeted regulatory relationship of miR-181a and SIRT1. LPS induced the upregulation of miR-181a, downregulation of SIRT1 and a strong inflammatory response. In addition, LPS stimulation inhibited the expression of Nrf2 and activated the NF-κB pathway. Moreover, the inhibition of miR-181a attenuated inflammatory response and apoptosis during LPS stimulation, which was implemented by up-regulating the expression of its target SIRT1. More fully, downregulation of SIRT1 by short hairpin interference resulted in a decreased expression of Nrf2, increased expression of p-P65 and proinflammatory cytokines, and intensive apoptosis. Downregulation of miR-181a could promote the expression of its target SIRT1, and then, attenuate inflammatory response and apoptosis via Nrf2 and NF-κB signaling pathways during LPS treatment. miR-181a can be a potential target of controlling the inflammatory response during sepsis and has important clinical significance for the treatment and rehabilitation of septic patients.