Integrin ανβ5 in vitro inhibition limits pro-fibrotic response in cardiac fibroblasts of spontaneously hypertensive rats

BackgroundTo date the TGF-1 activation mediated by integrin 5 during fibrosis is well-known. This process has been shown also in the heart, where cardiac fibroblasts (CF) differentiate into -smooth muscle actin (-SMA)-positive myofibroblasts (MyoFB). Here, we studied the effects on CF, isolated by spontaneously hypertensive rats (SHR), of integrin 5 inhibition in MyoFB differentiation.MethodsStaining and immunohistochemistry were performed on rat cardiac tissue. CF were isolated by enzymatic digestion from SHR (SHR-CF) and normotensive WKY (WKY-CF) rat hearts and then treated for in vitro evaluation.ResultsSHR heart tissues revealed a higher TGF-1 expression vs. WKY samples. SHR-CF showed an enhanced SMAD2/3 activation and an up-regulated expression of -SMA, a typical MyoFB marker, especially after TGF-1 treatment. Immunostaining on cardiac tissues revealed a higher expression of integrin 5 in SHR vs. WKY rat hearts. In vitro results confirmed the up-regulation of integrin 5 expression in SHR-CF at basal condition and after TGF-1 treatment, in comparison with WKY-CF. Inhibition of integrin 5 by cilengitide treatment led a decreased expression of 5, collagen I, and -SMA in SHR-CF vs. WKY-CF, resulting in a diminished differentiation of CF into MyoFB. Taking together, results suggested that SHR-CF are more susceptible to TGF-1, showing an up-regulated activation of SMAD2/3 signaling, and an increased 5, -SMA, and collagen I expression. Hypertension stimulus promoted an up-regulation of integrin 5 on SHR cardiac tissue and its in vitro inhibition reverted pro-fibrotic events of SHR-CF.ConclusionInhibition of integrin 5 exerted by cilengitide strongly diminished SHR-CF differentiation into detrimental MyoFB. So, integrin 5 might be considered a novel therapeutic target and cilengitide an effective pharmacological tool to limit the progression of hypertension-induced cardiac fibrosis.