Lipopolysaccharide induces pyroptosis through regulation of autophagy in cardiomyocytes.

Background: Autophagy, a stress response in eukaryotic cells, is closely related to cardiogenic diseases. Pyroptosis, a newly discovered way of programmed cell death, also plays an important role in cardiovascular disease. However, the role and relationship of autophagy and pyroptosis in lipopolysaccharide (LPS)-induced inflammatory response of cardiomyocytes were still unclear.

Methods: Western blot was performed to determine the expression of poly ADP-ribosepolmesera-1 (PARP-1), LC3B, NLRP3 and GSDMD in cardiomyocytes after the treatment of LPS. Transfection of si-LC3B, western blot and immunofluorescence (IF) staining were performed to investigate the role of autophagy in LPS-induced pyroptosis. Co-immunoprecipitation (Co-IP) assays and quantitative real-time PCR (qRT-PCR) were conducted to explore whether PARP-1 binding to LC3B and modulating its expression. Transfections of si-PARP-1, western blot and IF were carried out to confirm the role of PARP-1 in the regulation of LPS-induced pyroptosis by autophagy.

Results: LPS induces autophagy and pyroptosis in cardiomyocytes, enhanced the level of autophagy and inhibited the level of pyroptosis in the concentration of 4 µg/mL. We further proved that autophagy inhibits LPS-induced pyroptosis in cardiomyocytes. In addition, PARP-1 binding to LC3B and regulate the expression of LC3B. Finally, we proved that knockdown of PARP-1 rescued the inhibition of autophagy on LPS-induced pyroptosis of cardiomyocytes.

Conclusions: LPS induces pyroptosis through regulation of autophagy via PARP-1 at a specific concentration, above which it causes deposition of autophagy flow to promote pyroptosis. Inhibiting LPS-induced pyroptosis could be a promising therapeutic target in treating cardiovascular diseases.