Matrix Protein Tenascin-C Promotes Kidney Fibrosis via STAT3 activation in Response to Tubular Injury

Abstract: Accumulating evidence indicates that the extracellular matrix (ECM) is not only a consequence of fibrosis, but also contributes to the progression of fibrosis, by creating a pro-fibrotic microenvironment. Tenascin-C (TNC) is an ECM glycoprotein that contains multiple functional domains. We showed that following kidney injury, TNC was markedly induced in fibrotic areas in the kidney from both mouse models and humans with kidney diseases. Genetically deletion of TNC in mice significantly attenuated unilateral ureteral obstruction-induced kidney fibrosis. Further studies showed that TNC promoted the proliferation of kidney interstitial cells via STAT3 activation. To identify and characterize TNC expressing cells, we generated a TNC promoter driven CreER2-IRES-eGFP knock-in mouse line and found that the TNC reporter eGFP was markedly induced in cells around injured tubules that had lost epithelial markers, suggesting TNC was induced in response to epithelium injury. Most of the eGFP positive cells were both NG2 and PDGFRβ positive, only half of which were αSMA positive. These cells did not carry markers of progenitor cells or macrophages. In normal kidney, TNC is constitutively expressed by the renal medullary interstitial cells (RMICs) in renal papilla that has been reported to contain stem cells. Cell lineage tracing study revealed that the cells expressing TNC in renal cortex after fibrosis were not originated from these RMICs. In conclusion, this study provides strong evidence that matrix protein TNC contributes to kidney fibrosis. TNC pathway may serve as a potential therapeutic target for interstitial fibrosis and progression of chronic kidney disease.