Inhibition of (interstitial) P2Y6 receptors attenuates fibrosis progression.

Chronic kidney disease (CKD) affects over 850 million people worldwide and is characterized by progressive renal fibrosis driven by activated interstitial fibroblasts. Signaling by extracellular nucleotides and P2 receptors plays an important role in renal pathophysiology, yet its contribution to fibroblast activation and fibrosis remains poorly understood. Here, we investigated the expression and function of Gq/11-coupled P2Y receptors in renal interstitial fibroblasts and their involvement in experimental kidney fibrosis. Using highly selective RNA in situ hybridization, we detected P2Y1 (P2ry1) and P2Y6 (P2ry6) receptor expression in interstitial fibroblasts. Notably, P2Y6 expression was markedly upregulated in several experimental mouse models of renal fibrosis. Functional assays in primary cultured renal fibroblasts confirmed Gq/11-coupled P2Y receptor activity, as evidenced by transient intracellular Ca²⁺ elevations upon nucleotide stimulation. Primary cultured renal fibroblasts exhibited enhanced migration in response to extracellular uridine diphosphate (UDP). To assess the contribution of interstitial P2Y6 receptors to fibrosis progression, we employed an adenine-induced nephropathy model with or without the selective P2Y6 antagonist MRS2578. Pharmacological inhibition of P2Y6 significantly reduced the mRNA expression of the myofibroblast marker α-smooth muscle actin and collagen I. Collectively, these findings suggest that upregulated P2Y6 receptor signaling promotes the transition of resident interstitial cells into myofibroblasts during renal fibrosis, likely by modulating fibroblast migration. Inhibition of P2Y6 signaling could represent a new strategy for reducing excessive renal fibrosis.