TRIM45 aggravates microglia pyroptosis via Atg5/NLRP3 axis in septic encephalopathy

Abstract

Abstract Background Neuroinflammation mediated by microglia pyroptosis activation is an important pathogenesis of septic encephalopathy(SAE). It is reported that TRIM45 is associated with tumors and inflammatory diseases. However, the role of TRIM45 in SAE and the relationship between TRIM45 and microglia pyroptosis are unknown. In this study, we found that TRIM45 plays an important role in regulating microglia pyroptosis and its molecular mechanism. Methods SAE was induced by lps in mice transfected with adenovirus shTRIM45. BV2 was treated with lps + ATP in vitro. Cognitive function was assessed by Morris water maze. Nissl staining and Tunnel staining were used to evaluate histological and structural lesions. QPCR was used to detect mRNA level of inflammatory cytokines, NLRP3, autophagy proteins. Western blotting and immunofluorescence were used to analyze the expression of the proteins. The changes of ROS in cells were observed by flow cytometry, The changes of mitochondrial membrane potential in BV2 cells were detected by JC-1 staining. Peripheral blood mononuclear cells were extracted from blood by density gradient centrifugation and then used for QPCR and Western blotting analysis. In order to further explore its mechanism, we used overexpression plasmids TRIM45 and Atg5, siRNA-TRIM45 to analyze the downstream pathway of NLRP3. The protein and mRNA of TRIM45 in the peripheral blood mononuclear cells from sepsis patients were detected. Results Knocking down TRIM45 could protect the neuron damage and cognitive impairment of septic mice. TRIM45 knockdown can inhibit microglia pyroptosis and the secretion of inflammatory cytokines in vivo and in vitro, which is mediated by activating NLRP3/Gsdmd-N. Overexpression TRIM45 can activate NLRP3 and downstream proteins. Further exploration found that TRIM45 regulated the activation of NLRP3 by changing Atg5 protein and regulating autophagy flux. It was also found that overexpression and knockdown of TRIM45 would affect the changes of ROS and mitochondrial membrane potential. In short, knocking down TRIM45 can reduce microglia pyroptosis, reduce the secretion of pro-inflammatory cytokines, reduce neuronal damage and improve cognitive function. The levels of TRIM45 mRNA and protein in septic patients were increased, and TRIM45 mRNA level of peripheral blood monocytes and APACHE II score were positive linear correlation in some patients with sepsis. Conclusion TRIM45 plays a key role in neuroinflammation caused by lps, and the possible mechanism is that TRIM45 aggravates microglia pyroptosis via Atg5/NLRP3 axis.