Integrin alpha 11 in the regulation of the myofibroblast phenotype: implications for fibrotic diseases

Tissue fibrosis, characterized by excessive accumulation of aberrant extracellular matrix (ECM) produced by myofibroblasts, is a growing cause of mortality worldwide. Understanding the factors that induce myofibroblastic differentiation is paramount to prevent or reverse the fibrogenic process. Integrin-mediated interaction between the ECM and cytoskeleton promotes myofibroblast differentiation. In the present study, we explored the significance of integrin alpha 11 (ITGA11), the integrin alpha subunit that selectively binds to type I collagen during tissue fibrosis in the liver, lungs and kidneys. We showed that ITGA11 was co-localized with α-smooth muscle actin-positive myofibroblasts and was correlatively induced with increasing fibrogenesis in mouse models and human fibrotic organs. Furthermore, transcriptome and protein expression analysis revealed that ITGA11 knockdown in hepatic stellate cells (liver-specific myofibroblasts) markedly reduced transforming growth factor β-induced differentiation and fibrotic parameters. Moreover, ITGA11 knockdown dramatically altered the myofibroblast phenotype, as indicated by the loss of protrusions, attenuated adhesion and migration, and impaired contractility of collagen I matrices. Furthermore, we demonstrated that ITGA11 was regulated by the hedgehog signaling pathway, and inhibition of the hedgehog pathway reduced ITGA11 expression and fibrotic parameters in human hepatic stellate cells in vitro, in liver fibrosis mouse model in vivo and in human liver slices ex vivo. Therefore, we speculated that ITGA11 might be involved in fibrogenic signaling and might act downstream of the hedgehog signaling pathway. These findings highlight the significance of the ITGA11 receptor as a highly promising therapeutic target in organ fibrosis. A protein involved in binding collagen contributes to the organ-scarring disease known as fibrosis. Integrin alpha 11 (ITGA11) is known to bind collagen produced by myofibroblasts, injury-driven specific cells responsible for inducing fibrosis. A team led by Jai Prakash from the University of Twente in Enschede, The Netherlands, showed that ITGA11 is expressed at higher levels in the livers of mice with experimentally induced fibrosis than in healthy controls. In tissues taken from liver biopsies of fibrosis patients, levels of ITGA11 also tracked the expression of myofibroblasts. Remarkebly, blocking ITGA11 prevented the fibrotic activity of these cells. Similar results were seen in tissue from human fibrotic lung. The findings point to ITGA11 as a promising drug target for treating a range of fibrotic conditions.