Vascular smooth muscle-MAPK14 is required for neointimal hyperplasia by suppressing VSMC differentiation and inducing proliferation and inflammation

Redox Biol. 2019 Apr:22:101137. doi: 10.1016/j.redox.2019.101137. Epub 2019 Feb 6.


Injury-induced stenosis is a serious vascular complication. We previously reported that p38α (MAPK14), a redox-regulated p38MAPK family member was a negative regulator of the VSMC contractile phenotype in vitro. Here we evaluated the function of VSMC-MAPK14 in vivo in injury-induced neointima hyperplasia and the underlying mechanism using an inducible SMC-MAPK14 knockout mouse line (iSMC-MAPK14-/-). We show that MAPK14 expression and activity were induced in VSMCs after carotid artery ligation injury in mice and ex vivo cultured human saphenous veins. While the vasculature from iSMC-MAPK14-/- mice was indistinguishable from wildtype littermate controls at baseline, these mice exhibited reduced neointima formation following carotid artery ligation injury. Concomitantly, there was an increased VSMC contractile protein expression in the injured vessels and a decrease in proliferating cells. Blockade of MAPK14 through a selective inhibitor suppressed, while activation of MAPK14 by forced expression of an upstream MAPK14 kinase promoted VSMC proliferation in cultured VSMCs. Genome wide RNA array combined with VSMC lineage tracing studies uncovered that vascular injury evoked robust inflammatory responses including the activation of proinflammatory gene expression and accumulation of CD45 positive inflammatory cells, which were attenuated in iSMC-MAPK14-/- mice. Using multiple pharmacological and molecular approaches to manipulate MAPK14 pathway, we further confirmed the critical role of MAPK14 in activating proinflammatory gene expression in cultured VSMCs, which occurs in a p65/NFkB-dependent pathway. Finally, we found that NOX4 contributes to MAPK14 suppression of the VSMC contractile phenotype. Our results revealed that VSMC-MAPK14 is required for injury-induced neointima formation, likely through suppressing VSMC differentiation and promoting VSMC proliferation and inflammation. Our study will provide mechanistic insights into therapeutic strategies for mitigation of vascular stenosis.

Keywords: MAPK14; Neointima formation; Oxidative stress; Smooth muscle cell.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers
  • Carotid Arteries / metabolism
  • Carotid Arteries / pathology
  • Carotid Artery Injuries / etiology
  • Carotid Artery Injuries / metabolism
  • Carotid Artery Injuries / pathology
  • Cell Differentiation
  • Cell Proliferation
  • Fluorescent Antibody Technique
  • Gene Expression
  • Humans
  • Hyperplasia
  • Immunohistochemistry
  • Inflammation / etiology
  • Inflammation / metabolism
  • Inflammation / pathology
  • Inflammation Mediators
  • Mice
  • Mitogen-Activated Protein Kinase 14 / genetics
  • Mitogen-Activated Protein Kinase 14 / metabolism*
  • Muscle, Smooth, Vascular / metabolism*
  • Myocytes, Smooth Muscle / cytology
  • Myocytes, Smooth Muscle / metabolism*
  • NADPH Oxidase 4 / metabolism
  • Neointima / metabolism*
  • Neointima / pathology*
  • RNA, Small Interfering / genetics
  • Transcription Factor RelA / metabolism


  • Biomarkers
  • Inflammation Mediators
  • RELA protein, human
  • RNA, Small Interfering
  • Transcription Factor RelA
  • NADPH Oxidase 4
  • Mitogen-Activated Protein Kinase 14