Smooth muscle cell–specific fibronectin-EDA mediates phenotypic switching and neointimal hyperplasia
Manish Jain, Nirav Dhanesha, Prakash Doddapattar, Mehul R. Chorawala, Manasa K. Nayak, Anne Cornelissen, Liang Guo, Aloke V. Finn, Steven R. Lentz, Anil K. Chauhan
Manish Jain, Nirav Dhanesha, Prakash Doddapattar, Mehul R. Chorawala, Manasa K. Nayak, Anne Cornelissen, Liang Guo, Aloke V. Finn, Steven R. Lentz, Anil K. Chauhan
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Research Article Vascular biology

Smooth muscle cell–specific fibronectin-EDA mediates phenotypic switching and neointimal hyperplasia

Abstract

Fibronectin–splice variant containing extra domain A (Fn-EDA) is associated with smooth muscle cells (SMCs) following vascular injury. The role of SMC-derived Fn-EDA in SMC phenotypic switching or its implication in neointimal hyperplasia remains unclear. Herein, using human coronary artery sections with a bare metal stent, we demonstrate the expression of Fn-EDA in the vicinity of SMC-rich neointima and peri-strut areas. In mice, Fn-EDA colocalizes with SMCs in the neointima of injured carotid arteries and promotes neointima formation in the comorbid condition of hyperlipidemia by potentiating SMC proliferation and migration. No sex-based differences were observed. Mechanistic studies suggested that Fn-EDA mediates integrin- and TLR4-dependent proliferation and migration through activation of FAK/Src and Akt1/mTOR signaling, respectively. Specific deletion of Fn-EDA in SMCs, but not in endothelial cells, reduced intimal hyperplasia and suppressed the SMC synthetic phenotype concomitant with decreased Akt1/mTOR signaling. Targeting Fn-EDA in human aortic SMCs suppressed the synthetic phenotype and downregulated Akt1/mTOR signaling. These results reveal that SMC-derived Fn-EDA potentiates phenotypic switching in human and mouse aortic SMCs and neointimal hyperplasia in the mouse. We suggest that targeting Fn-EDA could be explored as a potential therapeutic strategy to reduce neointimal hyperplasia.

Authors

Manish Jain, Nirav Dhanesha, Prakash Doddapattar, Mehul R. Chorawala, Manasa K. Nayak, Anne Cornelissen, Liang Guo, Aloke V. Finn, Steven R. Lentz, Anil K. Chauhan

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Figure 1

Detrimental role of Fn-EDA in intimal hyperplasia.

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Detrimental role of Fn-EDA in intimal hyperplasia. (A) Representative im...
(A) Representative images of cross-sectional immunohistochemistry in stented human coronary arteries showed Fn-EDA in SMC-rich neointima and peri-strut areas. Left panel shows H&E staining, middle panel shows Fn-EDA, and right panel shows α-smooth muscle actin (αSMA) staining. Boxed regions are magnified. “S” denotes strut in the cross sections; dark areas are pieces of strut sections. (B) Representative images showing double immunostaining for Fn-EDA (red) and SMCs (green) in the uninjured and injured carotid artery of Apoe–/– mice harvested after 14 and 28 days of injury (n = 5–6 per group). Nuclei are counterstained with Hoechst (blue). Boxed regions are magnified. Scale bars: 50 μm. (C) Representative scatter plot and intensity profile demonstrating colocalized pixels and pixel intensity for both channels (Fn-EDA, red, x axis; and SMC, green, y axis) with Pearson’s correlation coefficient (PCC). Colocalized pixels are defined as those whose intensity values for both channels fall within a preset range above the background intensity level (white arrows). (D) Quantification of the Fn-EDA fluorescence intensity. (E) Representative photomicrographs of Verhoeff’s/van Gieson–stained carotid artery sections of male and female Fn-EDA–/– Apoe–/– and Apoe–/– mice after 28 days of injury (n = 10 per group). Scale bars: 200 μm. (F) Quantification shows intimal area, medial area, and a ratio of intimal to medial area. Each dot represents a single mouse. Values are represented as mean ± SEM. Statistical analysis: unpaired Student’s t test.