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Abstract: PO2436

Release of ATP from Renal Tubular Epithelial Cells via Connexin 43 Deteriorates Renal Fibrosis After Unilateral Ureteral Obstruction

Session Information

Category: CKD (Non-Dialysis)

  • 2103 CKD (Non-Dialysis): Mechanisms

Author

  • Zeng, Rui, Huazhong University of Science and Technology Tongji Medical College, Wuhan, Hubei, China
Background

As a kind of DAMPs (Danger associated molecular patterns), ATP is released after stress or injury through ATP-permeable channels, most likely to be connexin hemichannel proteins. Among which, connexin 43 (Cx43) is the most common member. However, its role on renal injury and the following fibrosis has not been examined.

Methods

We analyzed renal samples from patients with obstructive nephropathy and applied unilateral ureteral obstruction (UUO) to induce renal fibrosis in mice. Cx43-KSP mice were generated to deplete the Cx43 gene of renal tubular epithelial cells (TECs). Through transcriptomics, metabolomics, and single-cell sequencing multi-omics analysis, the relationship among Cx43, ATP, and macrophage in renal fibrosis was explored.

Results

The expression of Cx43 upregulated in TECs after UUO in mice or in patients with obstructive nephropathy. Knockdown of Cx43 in TECs or using Cx43 specific inhibitors reduced UUO induced-inflammation and fibrosis. Single cell RNA sequencing and immunoflurence showed that the distribution of ATP specific receptors is mainly on macrophages, including P2rx4 and P2rx7. These receptor positive macrophages were undergoing pyroptosis after UUO. In vitro, ATP directly induced macrophage pyroptosis. The administration of P2 receptor and P2rx7 receptor inhibitors to UUO mice inhibited macrophage pyroptosis and demonstrated a similar renoprotection as the Cx43 knocking out. Further, we found the GAP19/26 (Cx43 hemichannel inhibitor peptide) and A-839977 (the inhibitor of pyroptosis receptor) alleviated UUO induced fibrosis, while BzATP (the agonist of pyroptosis receptor) exacerbated fibrosis. Single cell sequencing demonstrated that the pyroptotic macrophages upregulated the expression of CXCL 10, which in turn activated fibroblasts.

Conclusion

Cx43 hemichannel mediates the outflow of ATP in TECs inducing macrophage pyroptosis, which subsequently secretes CXCL 10 promoting fibroblast activation and renal fibrosis.