Lipopolysaccharide-induced bacterial infection model: microRNA-370-3p participates in the anti-infection response by targeting the macrophage TLR4-NLRP3 caspase-1 cellular pyroptosis pathway.

Objective: To explore the effect of miR-370-3p on LPS triggering, in particular its involvement in disease progression by targeting the TLR4-NLRP3-caspase-1 cellular pyroptosis pathway in macrophages.

Methods: Human macrophage RAW264.7 was divided into 6 groups: control, LPS, LPS + inhibitor-NC, LPS + miR-370-3p inhibitor, LPS + mimics-NC and LPS + miR-370-3p mimics. RT-qPCR was used to detect the expression level of miR-370-3p and analyzed comparatively. CCK-8 and flow cytometry assays were used to detect cell viability and apoptosis. ELISA assay was used to detect the levels of IL-1β and TNF-α in the supernatant of the cells. The WB assay was used to detect TLR4, NLRP3, Caspase-1 and GSDMD levels.

Results: After LPS induction, macrophage miR-370-3p levels decreased, cell viability decreased, and apoptosis increased. At the same time, the levels of TLR4, NLRP3, Caspase-1 and GSDMD increased in the cells, and the levels of IL-1β and TNF-α increased in the cell supernatant. Compared with the LPS group, the significantly higher expression level of miR-370-3p in the cells of the LPS + miR-370-3p mimics group was accompanied by significantly higher cell viability, significantly lower apoptosis rate, significantly lower levels of TLR4, NLRP3, Caspase-1, and GSDMD in the cells, and significantly lower levels of IL-1β and TNF-α in the cell supernatant.

Conclusion: MiR-370-3p may be involved in anti-infective immune responses by targeting and inhibiting the macrophage TLR4-NLRP3-caspase-1 cellular pyroptosis pathway.