Integrin α9 regulates smooth muscle cell phenotype switching and vascular remodeling
Manish Jain, … , Nirav Dhanesha, Anil K. Chauhan
Manish Jain, … , Nirav Dhanesha, Anil K. Chauhan
Published May 24, 2021
Citation Information: JCI Insight. 2021;6(10):e147134. https://doi.org/10.1172/jci.insight.147134.
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Research Article Vascular biology

Integrin α9 regulates smooth muscle cell phenotype switching and vascular remodeling

Abstract

Excessive proliferation of vascular smooth muscle cells (SMCs) remains a significant cause of in-stent restenosis. Integrins, which are heterodimeric transmembrane receptors, play a crucial role in SMC biology by binding to the extracellular matrix protein with the actin cytoskeleton within the SMC. Integrin α9 plays an important role in cell motility and autoimmune diseases; however, its role in SMC biology and remodeling remains unclear. Herein, we demonstrate that stimulated human coronary SMCs upregulate α9 expression. Targeting α9 in stimulated human coronary SMCs, using anti–integrin α9 antibody, suppresses synthetic phenotype and inhibits SMC proliferation and migration. To provide definitive evidence, we generated an SMC-specific α9-deficient mouse strain. Genetic ablation of α9 in SMCs suppressed synthetic phenotype and reduced proliferation and migration in vitro. Mechanistically, suppressed synthetic phenotype and reduced proliferation were associated with decreased focal adhesion kinase/steroid receptor coactivator signaling and downstream targets, including phosphorylated ERK, p38 MAPK, glycogen synthase kinase 3β, and nuclear β-catenin, with reduced transcriptional activation of β-catenin target genes. Following vascular injury, SMC-specific α9-deficient mice or wild-type mice treated with murine anti–integrin α9 antibody exhibited reduced injury-induced neointimal hyperplasia at day 28 by limiting SMC migration and proliferation. Our findings suggest that integrin α9 regulates SMC biology, suggesting its potential therapeutic application in vascular remodeling.

Authors

Manish Jain, Rishabh Dev, Prakash Doddapattar, Shigeyuki Kon, Nirav Dhanesha, Anil K. Chauhan

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Figure 7

Infusion of anti–integrin α9 antibody reduces injury-induced neointimal hyperplasia in WT mice.

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Infusion of anti–integrin α9 antibody reduces injury-induced neointimal ...
Serum-starved SMCs from WT mice were pretreated with murine specific anti-α9 blocking antibody (clone 55A2C, 10 μg/mL) for 60 minutes and then stimulated with or without PDGF-BB for 24 hours. (A) The top panels show representative BrdU-positive (red) cells costained with αSMA (green) and Hoechst (blue). Scale bars: 50 μm. The bottom panels show representative phase-contrast images of SMC migration in the scratch assay. Scale bars: 500 μm. The right panel shows the quantification of BrdU-positive cells to the total number of cells (n = 5) and migrated area (n = 6). (B–D) Male WT mice were treated with 55A2C (200 μg/mouse) or control Ig. Wire injury was performed in the carotid artery after 60 minutes, and arteries were harvested after 28 days. (B) The left panels show representative photomicrographs of Verhoeff’s van Gieson–stained carotid artery sections. Scale bars: 200 μm. The right panels show quantification of intimal area, medial area, and a ratio of intimal to medial area. Each dot represents a single mouse (n = 8–9/group). (C) The left panels show representative BrdU-positive cells (red) counterstained with αSMA (green). Nuclei are counterstained with Hoechst (blue). The right panel shows the quantification of percentage BrdU-positive cells (n = 6). Scale bars: 200 μm. (D) The left panels show representative TUNEL-positive cells (green) counterstained with Hoechst (blue). The right panel shows the quantification of TUNEL-positive cells (n = 6). Scale bars: 200 μm. Values are represented as mean ± SEM. Statistical analysis: (A) 1-way ANOVA with Bonferroni’s post hoc test; (B–D) unpaired 2-tailed Student’s t test. *P < 0.05 vs. quiescent or vehicle-treated (control Ig) groups. (E) Schematic showing the mechanism by which SMC-specific integrin α9 mediates SMC proliferation, migration, and neointimal hyperplasia.