Inhibiting miR-186-5p relieves traumatic brain injury by regulating insulin-like growth factor-I-NLRP3/ASC/caspase-1 signaling pathway.

Previous studies have shown that micro-RNA (miR)-186-5p can affect apoptosis of cells by regulating insulin-like growth factor-I (IGF-1). However, the role of miR-186-5p-IGF1 axis in traumatic brain injury (TBI), especially oxidative stress and neuroinflammatory response, remains to be further studied. Lipopolysaccharide (5 μg/mL) was used to activate microglia in vitro . The expression of miR-186-5p, IGF-1 was detected by quantitative reverse transcription PCR (qRT-PCR). ELISA and western blot were used to detect the inflammatory factors and oxidative stress. Western blot was used to detect apoptotic proteins (Bax, Bcl2 and C-caspase3), inflammatory proteins (iNOS and COX2), oxidative stress proteins (Nrf2 and HO-1) and NLRP3/apoptosis-associated speck-like protein containing a CARD (ASC)/caspase-1 inflammatory bodies. MiR-186-5p inhibitor could reduce the inflammatory factors and oxidative stress in BV2 treated with lipopolysaccharide, and reduce apoptosis. In addition, we also found that inhibition of miR-186-5p increased the expression of IGF-1, which is necessary for nervous system development. Luciferase activity assay confirmed that IGF-1 was the direct target gene of miR-186-5p. Inhibiting miR-186-5p, through upregulation IGF-1, attenuates the inflammatory factors, oxidative stress and by inhibiting NLRP3/ASC/caspase-1 signal pathway TBI in-vitro model.