Inhibition of Integrin αvβ6, an Activator of Latent Transforming Growth Factor-β, Prevents Radiation-induced Lung Fibrosis

Rationale: In experimental models, lung fibrosis is dependent on transforming growth factor (TGF)-β signaling. TGF-β is secreted in a latent complex with its propeptide, and TGF-β activators release TGF-β from this complex. Because the integrin αvβ6 is a major TGF-β activator in the lung, inhibition of αvβ6-mediated TGF-β activation is a logical strategy to treat lung fibrosis

αvβ6 Integrin Regulates Renal Fibrosis and Inflammation in Alport Mouse

The transforming growth factor (TGF)-β-inducible integrin αvβ6 is preferentially expressed at sites of epithelial remodeling and has been shown to bind and activate latent precursor TGF-β. Herein, we show that αvβ6 is overexpressed in human kidney epithelium in membranous glomerulonephritis, diabetes mellitus, IgA nephropathy, Goodpasture’s syndrome, and Alport syndrome renal epithelium. To assess the potential regulatory role of αvβ6 in renal disease, we studied the effects of function-blocking αvβ6 monoclonal antibodies (mAbs) and genetic ablation of the β6 subunit on kidney fibrosis in Col4A3(−/−) mice, a mouse model of Alport syndrome. Expression of αvβ6 in Alport mouse kidneys was observed primarily in cortical tubular epithelial cells and in correlation with the progression of fibrosis. Treatment with αvβ6-blocking mAbs inhibited accumulation of activated fibroblasts and deposition of interstitial collagen matrix. Similar inhibition of renal fibrosis was observed in β6-deficient Alport mice. Transcript profiling of kidney tissues showed that αvβ6-blocking mAbs significantly inhibited disease-associated changes in expression of fibrotic and inflammatory mediators. Similar patterns of transcript modulation were produced with recombinant soluble TGF-β RII treatment, suggesting shared regulatory functions of αvβ6 and TGF-β. These findings demonstrate that αvβ6 can contribute to the regulation of renal fibrosis and suggest this integrin as a potential therapeutic target