Micheliolide Ameliorates Diabetic Kidney Disease By Inhibiting Mtdh-mediated Renal Inflammation

BackgroundDiabetic kidney disease(DKD)is the leading cause of end-stage renal disease in China,with unsatisfied treatment at present.In-depth exploration of the pathogenesis of DKD and development of effective therapeutic strategies are major issues of the global nephrology community.Inflammation plays a key role in the pathogenesis of DKD,but the molecular mechanism is not completely clear.The nuclear factor-κB(NF-κB)signaling pathway plays a central role in the inflammatory process in DKD.Thus,agents inhibit NF-κB inflammatory signaling pathway may be useful for treating DKD.Micheliolide(MCL)is a novel guaianolide sesquiterpene lactone,which is developed base the structure of parthenolide(PTL),a well-known NF-κB inhibitor,with better water solubility,stability and bioactivity.Dimethylaminomicheliolide(DMAMCL),the pro-drug of MCL,exerts remarkable anti-cancer and anti-inflammatory effects.Our previous research found that DMAMCL can improve peritoneal fibrosis and renal fibrosis,whether DMACCL has a therapeutic effect on DKD remains to be studied.Metadherin(Mtdh)is a prominent oncogene which involved in tumor cell survival,proliferation,angiogenesis and inflammatory response via the regulation of multiple signaling pathways.However,whether it regulates tubular inflammation in DKD requires further analysisObjectivesThis study was conducted to investigate the therapeutic effects of DMAMCL on DKD,the role of Mtdh in DKD kidney inflammation and the regulatory mechanism of MCL on Mtdh expression.MethodsThis study used db/db mice and high glucose-induced mouse renal tubular cell lines(mTEC)as in vitro and in vivo models of DKD respectively Immunohistochemical staining and western blot were used to detect protein expression.Real-time quantitative PCR was used to detect mRNA expression,immunofluorescence staining was used to observe the distribution and expression of p65 in cells.Lentiviral infection and plasmid transfection were used to down-regulated or over-expressed Mtdh in mTEC.Luciferase reporter gene experiment was used to detect the effect of MCL on Mtdh transcription level,pull down test was used to detect the binding of MCL and Mtdh,the ubiquitination of Mtdh was detected by Co-immunoprecipitation.ResultsThe results show that DMAMCL effectively improved renal function and reduce urinary protein excretion in DKD mice.DAMCL(MCL)inhibited the activation of NF-κB inflammatory signaling pathway and the production of inflammatory factors in DKD models.Mtdh expression was significantly increased in the kidney tissue of DKD mice and high glucose-induced mTEC.Mtdh blockage in vitro inhibited the activation of NF-κB inflammatory signaling pathway and the production of inflammatory factors.DMAMCL and MCL decreased Mtdh expression in vivo and in vitro respectively,and MCL inhibited Mtdh-overexpression-induced NF-κB inflammatory signaling pathway and the production of inflammatory factors.Further investigation of the molecular mechanism by which MCL inhibits Mtdh expression revealed that MCL inhibits the transcription of Mtdh and promote its ubiquitination degradation pathway.ConclusionsIn summary,we found that DMAMCL had a good therapeutic effect on DKD mice,and the expression of Mtdh was increased the renal tissue of DKD mice and high glucose-induced tubule cells and Mtdh promotes renal inflammation by activating the NF-κB signaling pathway.DMAMCL inhibited the expression of Mtdh by inhibiting Mtdh transcription and promoting its ubiquitination degradation,which may be one of the important mechanisms of DMAMCL in improving DKD renal injury.