Pharmacologic Blockade of αvβ1 Integrin Ameliorates Renal Failure and Fibrosis In Vivo

Abstract

Activated fibroblasts are deemed the main executors of organ fibrosis. However, regulation of the pathologic functions of these cells <i>in vivo</i> is poorly understood. PDGF receptor <i>β</i> (PDGFR<i>β</i>) is highly expressed in activated pericytes, a main source of fibroblasts. Studies using a PDGFR<i>β</i> promoter-driven Cre system to delete <i>α</i>v integrins in activated fibroblasts identified these integrins as core regulators of fibroblast activity across solid organs, including the kidneys. Here, we used the same PDGFR<i>β</i>-Cre line to isolate and study renal fibroblasts <i>ex vivo</i> We found that renal fibroblasts express three <i>α</i>v integrins, namely <i>α</i>v<i>β</i>1, <i>α</i>v<i>β</i>3, and <i>α</i>v<i>β</i>5. Blockade of <i>α</i>v<i>β</i>1 prevented direct binding of fibroblasts to the latency-associated peptide of TGF-<i>β</i>1 and prevented activation of the latent TGF-<i>β</i> complex. Continuous administration of a recently described potent small molecule inhibitor of <i>α</i>v<i>β</i>1, compound 8, starting the day of unilateral ureteral obstruction operation, inhibited collagen deposition in the kidneys of mice 14 days later. Compound 8 also effectively attenuated renal failure, as measured by BUN levels in mice fed an adenine diet known to cause renal injury followed by fibrosis. Inhibition of <i>α</i>v<i>β</i>1 integrin could thus hold promise as a therapeutic intervention in CKD characterized by renal fibrosis.