Panax notoginseng Saponins Alleviate LPS-induced Fibrosis of HK-2 Cells by Inhibiting the Activation of NLRP3 Inflammasome and Pyroptosis

Background: Renal fibrosis is related to impaired kidney function and can eventually lead to end-stage renal disease, for which no effective treatment is available. Panax notoginseng saponins (PNS), as a commonly used traditional Chinese medicine, is considered a possible alternative for the treatment of fibrosis.Objective: The purpose of the present study was to investigate the effects and possible mechanisms of PNS on renal fibrosis.Methods: HK-2 cells were used to induce renal fibrosis cell model by lipopolysaccharide (LPS), and the cytotoxicity of PNS on HK-2 cells was investigated. Cell damage, pyroptosis, and fibrosis were analyzed to investigate the effects of PNS on LPS-induced HK-2 cells. NLRP3 agonist Nigericin was used further to explore the inhibitory effect of PNS on LPS-induced pyroptosis so as to clarify the possible mechanism of PNS on renal fibrosis.Results: PNS had no cytotoxicity on HK-2 cells, and could reduce the apoptosis and the release of lactate dehydrogenase (LDH) and inflammatory cytokines of LPS-induced HK-2 cells, showing an alleviating effect on cell damage. PNS also reduced the expression of pyroptosis proteins NLRP3, IL-1 beta, IL-18, and Caspase-1, as well as fibrosis proteins alpha-SMA, collagen I and p-Smad3/Smad3, which showed an inhibitory effect on LPS-induced pyroptosis and fibrosis. In addition, LPS-induced cell damage, pyroptosis, and fibrosis were aggravated after Nigericin treatment, while PNS alleviated the aggravation caused by Nigericin.Conclusion: PNS inhibited pyroptosis by inhibiting the activation of NLRP3 inflammasome in LPS-induced HK-2 cells, which ultimately alleviated renal fibrosis and played a good role in the treatment of kidney diseases.