Abstract
Background and Objective: Acute kidney injury (AKI) is a complication of sepsis. Pyroptosis of gasdermin D (GSDMD)-mediated tubular epithelial cells (TECs) play important roles in pathogenesis of sepsis-associated AKI. Long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3), an imprinted gene involved in tumorigenesis, is implicated in pyroptosis occurring in multiple organs. Herein, we investigated the role and mechanisms of MEG3 in regulation of TEC pyroptosis in lipopolysaccharide (LPS)-induced AKI.Materials and Methods: Male C57BL/6 mice and primary human TECs were treated with LPS for 24 h to establish the animal and cell models, respectively, of sepsis-induced AKI. Renal function was assessed by evaluation of serum creatinine and urea levels. Renal tubule injury score was assessed by Periodic acid-Schiff staining. Renal pyroptosis was assessed by evaluating expression of caspase-1, GSDMD, and inflammatory factors IL-1β and IL-18. Cellular pyroptosis was assessed by analyzing the release rate of LDH, expression of IL-1β, IL-18, caspase-1, and GSDMD, and using EtBr and EthD2 staining. MEG3 expression in renal tissues and cells was detected using RT-qPCR. The molecular mechanisms of MEG3 in LPS-induced AKI were assessed through bioinformatics analysis, RNA-binding protein immunoprecipitation, dual luciferase reporter gene assays, and a rescue experiment.Results: Pyroptosis was detected in both LPS-induced animal and cell models, and the expression of MEG3 in these models was significantly up-regulated. MEG3-knockdown TECs treated with LPS showed a decreased number of pyroptotic cells, down-regulated secretion of LDH, IL-1β, and IL-18, and decreased expression of GSDMD, compared with those of controls; however, there was no difference in the expression of caspase-1 between MEG3 knockdown cells and controls. Bioinformatics analysis screened out miR-18a-3P, and further experiments demonstrated that MEG3 controls GSDMD expression by acting as a ceRNA for miR-18a-3P to promote TECs pyroptosis.Conclusion: Our study demonstrates that lncRNA MEG3 promoted renal tubular epithelial pyroptosis by regulating the miR-18a-3p/GSDMD pathway in LPS-induced AKI.
Highlights
Sepsis, a syndrome characterized by systemic inflammation caused by infection, has become a global health problem (Singer et al, 2016; Rhodes et al, 2017)
maternally expressed gene 3 (MEG3)-knockdown tubular epithelial cells (TECs) treated with LPS showed a decreased number of pyroptotic cells, down-regulated secretion of LDH, IL-1β, and IL-18, and decreased expression of gasdermin D (GSDMD), compared with those of controls; there was no difference in the expression of caspase1 between MEG3 knockdown cells and controls
MEG3 Promotes Renal TEC Pyroptosis out miR-18a-3P, and further experiments demonstrated that MEG3 controls GSDMD expression by acting as a ceRNA for miR-18a-3P to promote TECs pyroptosis
Summary
A syndrome characterized by systemic inflammation caused by infection, has become a global health problem (Singer et al, 2016; Rhodes et al, 2017). Studies have shown that pyroptosis of TECs plays an important role in the pathogenesis of sepsis-related AKI (Ye et al, 2019; Zhou et al, 2020). The classic pathway of pyroptosis involves inflammasome-mediated activation of caspase-1, which leads to the cleavage of gasdermin D (GSDMD) into the active N-terminal and formation of a cell membrane pore; these events promote the production and release of proinflammatory mediators, such as IL-1β and IL-18, thereby producing a waterfall-level inflammatory response (Shi et al, 2015; Broz and Dixit, 2016). It is important to explore the regulatory mechanisms of GSDMD in TEC pyroptosis during sepsis-related AKI. Pyroptosis of gasdermin D (GSDMD)-mediated tubular epithelial cells (TECs) play important roles in pathogenesis of sepsis-associated AKI. We investigated the role and mechanisms of MEG3 in regulation of TEC pyroptosis in lipopolysaccharide (LPS)-induced AKI
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