Microvessel vascular smooth muscle cells contribute to collagen type I deposition through ERK1/2 MAP kinase, αvβ3-integrin, and TGF-β1 in response to ANG II and high glucose

This study determines that vascular smooth muscle cell (VSMC) signaling through extracellular signalregulated kinase (ERK) 1/2-mitogen-activated protein (MAP) kinase, alpha v beta(3)-integrin, and transforming growth factor (TGF)-beta 1 dictates collagen type I network induction in mesenteric resistance arteries (MRA) from Type 1 diabetic (streptozotocin) or hypertensive (HT; ANG II) mice. Isolated MRA were subjected to a pressure-passive-diameter relationship. To delineate cell types and mechanisms, cultured VSMC were prepared from MRA and stimulated with ANG II (100 nM) and high glucose (HG, 22 mM). Pressure-passive-diameter relationship reduction was associated with increased collagen type I deposition in MRA from HT and diabetic mice compared with control. Treatment of HT and diabetic mice with neutralizing TGF-beta 1 antibody reduced MRA stiffness and collagen type I deposition. Cultured VSMC stimulated with HG or ANG II for 5 min increased ERK1/2-MAP kinase phosphorylation, whereas a 48-h stimulation induced latent TGF-beta 1, alpha v beta(3)-integrin, and collagen type 1 release in the conditioned media. TGF-beta 1 bioactivity and Smad2 phosphorylation were alpha v beta(3)-integrin-dependent, since beta(3)-integrin antibody and alpha v beta(3)-integrin inhibitor (SB-223245, 10 mu M) significantly prevented TGF-beta 1 bioactivity and Smad2 phosphorylation. Pretreatment of VSMC with ERK1/2-MAP kinase inhibitor (U-0126, 1 mu M) reduced alpha v beta(3)-integrin, TGF-beta 1, and collagen type 1 content. Additionally, alpha v beta(3)-integrin antibody, SB-223245, TGF-beta 1-small-intefering RNA (siRNA), and Smad2-siRNA (40 nM) prevented collagen type I network formation in response to ANG II and HG. Together, these data provide evidence that resistance artery fibrosis in Type 1 diabetes and hypertension is a consequence of abnormal collagen type I release by VSMC and involves ERK1/2, alpha v beta(3)-integrin, and TGF-beta 1 signaling. This pathway could be a potential target for overcoming small artery complications in diabetes and hypertension.