CXCL6 Orchestrates Macrophage-Driven Inflammation in Diabetic Kidney Disease and Represents a Druggable Target.

Introduction: Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease and is increasingly recognized to involve early and progressive tubulointerstitial injury. However, the key molecular drivers of this process and their therapeutic potential remain poorly defined. Methods: We conducted an integrative analysis of three DKD transcriptomic datasets using weighted gene correlation network analysis and differential expression analysis, followed by single-cell RNA sequencing to localize candidate genes to specific renal cell types. Functional validation was performed using in vitro assays in HK-2 and THP-1 cells, in vivo DKD mouse models, and patient kidney tissue. A virtual screening approach was applied to identify candidate inhibitors. Results: We identified CXCL6, a C-X-C motif chemokine, as a central hub gene selectively upregulated in tubular epithelial cells of DKD kidneys. Urinary CXCL6 levels strongly correlated with markers of renal dysfunction. Mechanistically, high-glucose-induced CXCL6 expression in tubular cells, promoting macrophage recruitment, polarization toward a pro-inflammatory phenotype, and increased cytokine release. Through virtual screening, we identified salvianolic acid B (Sal-B) as a putative CXCL6 inhibitor. Sal-B treatment suppressed CXCL6 secretion, macrophage infiltration, and inflammatory cytokine production in vitro. Conclusion: Our study uncovers CXCL6 as a key mediator of tubulointerstitial inflammation in DKD, linking tubular injury to immune cell recruitment and cytokine-driven damage. Furthermore, we identify Sal-B as a promising therapeutic candidate targeting this newly characterized pathway, offering potential for diagnostic and therapeutic advancement in DKD.