MiRNA-494 specifically inhibits SIRT3-mediated microglia activation in sepsis-associated encephalopathy

BACKGROUND: Sepsis-associated encephalopathy (SAE) is characterized by the activation of inflammatory cascades, in which microglia play a key role. The activation of Recombinant Sirtuin 3 (SIRT3) was shown to significantly reduce the susceptibility of microglia to inflammatory stress. The purpose of this study is to determine whether miRNA-494 can regulate the activation and oxidative stress of SAE microglia through SIRT3. METHODS: An SAE rat model was established, and the expression of Ionized calcium bindingadaptor molecule-1 (Iba-1) in rat brain tissue was detected by immunohistochemistry. Enzyme-linked immuno sorbent assay was performed to detect the expression of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in brain tissue. Real time quantitative PCR was performed to detect the relative expression of SIRT3 and related miRNAs, while Western blot was used to detect the protein expression of SIRT3. Rat microglia cells were cultured in vitro. After miRNA-494 was transfected, the expression of TNF-α and IL-6 was detected. Western blot was used to detect the protein expression of SIRT3 and Iba-1 in microglia. RESULTS: The results showed that the expression of Iba-1 in the brain tissue of the SAE model group increased, and the expression of inflammatory factors TNF-α and IL-6 increased significantly (P<0.01). The expression of SIRT3 protein and mRNA in the brain tissue of the SAE model group also significantly increased (P<0.05). The relative expression of miRNA-494 in the SAE model group was significantly lower than that in the control group (P<0.01). After miRNA-494 was transfected into microglia, cells were treated with lipopolysaccharide. In the miRNA transfection group, the expression levels of TNF-α and IL-6 were significantly lower than those in the negative control (NC) group (P<0.01), and the protein expression levels of Iba-1 and SIRT3 were also significantly lower than those in the NC (P<0.01). CONCLUSIONS: MiRNA-494 may further regulate the activation of microglia in SAE by regulating mitochondrial function, providing basic research data for the development of new SAE treatment methods.