The Role And Mechanism Of Rictor/mTORC2 In Macrophage Activation And Renal Fibrosis

Our published study reported that Rictor/mTORC2 signaling mediates TGFβ1-induced fibroblast activation and kidney fibrosis.However,the role and mechanisms for Rictor/mTORC2 in macrophage activation are not clear.In this study,primary cultural macrophages from bone marrow(BMMs)with tamoxifen-induced specific deletion of Rictor were generated.In macrophages derived from bone marrow(BMMs),deletion of Rictor or blockade of PKCa inhibited cell migration treated with or without TGFβ1.Additionally,deletion of Rictor or blockade of Akt abolished IL4 or TGFβI stimulated macrophage M2 polarization.TGFβ1 could induce the mRNA expression of CTGF,PDGFA,PDGFB and VEGFC in primary cultured Rictor+/+BMMs,which were much less in Rictor-/-BMMs.Conditioned cultural medium(CM)from Rictor+/+,but not Rictor-/-BMMs efficiently promoted fibroblasts to express FN and a-SMA.The multiple profibrotic cytokine expression in macrophages depends on mTORC2/Akt signaling pathway.Together,these results suggest that Rictor/mTORC2 signaling plays an important role for macrophage activation.Macrophage accumulation plays a critical role for kidney fibrosis in chronic kidney diseases.In the first part of our study,we found that Rictor/mTORC2 in macrophages promotes the migration,M2 polarization and the expression of multiple profibrotic cytokines.In this part of the study,we focus on the role of Rictor/mTORC2 in macrophages in unilateral ureter obstruction(UUO)or ischemia/reperfusion injury(IRI)induced renal fibrosis.We report here that Rictor/mTORC2 was activated in macrophages from the fibrotic kidneys in mice.Ablation of Rictor in macrophages diminished kidney fibrosis,inflammatory cell accumulation,macrophage proliferation and polarization after UUO or IRI.Furthermore,mice adoptive transfer of Rictor-/-BMMs developed less kidney fibrosis compared to those transfer of Rictor+/+ BMMs.Together,these results suggest that Rictor/mTORC2 signaling is critical for promoting macrophage activation and kidney fibrosis.Targeting this signaling pathway in macrophages may shed new light on protecting against kidney fibrosis in patients with CKD fibrosis.At present,there is no specific medicine for the treatment of renal fibrosis.The aim of this study was to develop medicines for the therapy of renal fibrosis.Our previous studies found that mTORC2 signaling plays an important role in macrophage activation and renal fibrosis.We hypothesized that targeting this signaling pathway may reduce macrophage infiltration and renal fibrosis.We found that quercetin can target mTORC2 by reviewing the literatures.Quercetin,(3,3,4,5,7-pentahydroxyflavone),a flavonoid found in a wide variety of plants and presented in human diet,displays promising potential in anti-inflammatory activity.Go6976 can target downstream signaling molecule of mTORC2.Go6976 is a selective inhibitor of PKCa signaling activation.In this study,we found that after injecting quercetin or Go6976 into the UUO mice,macrophages accumulation and kidney interstitial fbrosis were largely ameliorated in fibrotic kidneys compared with mice injected with vehicle.Therefore,this study found that targeting mTORC2 signaling pathway,quercetin and Go6976 have potential clinical application and could probably be used for the therapy of renal fibrosis.