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MED1 Deficiency in Macrophages Accelerates Intimal Hyperplasia via ROS Generation and Inflammation

Yali Zhang1,2, Yu Fu2, Chenyang Zhang1,2

  • 1Research Institute of Atherosclerotic Disease, Xi'an Jiaotong University Cardiovascular Research Centre, Xi'an, Shaanxi 710061, China.

Oxidative Medicine and Cellular Longevity
|December 2, 2021
PubMed

Insights

Mediator complex subunit 1 (MED1) deficiency in macrophages worsens intimal hyperplasia and inflammation after vascular injury. This may stem from increased reactive oxygen species and activation of NF-κB and STAT1 pathways.

Area of Science:

  • Molecular Biology
  • Immunology
  • Cardiovascular Research

Background:

  • Mediator complex subunit 1 (MED1) is a transcriptional coactivator crucial for gene regulation.
  • Previous studies indicated a protective role for MED1 in macrophages against atherosclerosis.
  • The impact of MED1 deletion in macrophages on intimal hyperplasia and inflammation remained unclear.

Purpose of the Study:

  • To investigate the role of macrophage-specific MED1 deletion in intimal hyperplasia.
  • To elucidate the mechanisms by which MED1 deficiency regulates proinflammatory cytokine production.
  • To explore the effects of MED1 deficiency on vascular smooth muscle cell (VSMC) behavior.

Main Methods:

  • Utilized MED1 macrophage-specific knockout (MED1 KO) mice and wild-type littermates.
  • Assessed neointimal hyperplasia, VSMC, and macrophage accumulation in injured arteries.
  • Analyzed proinflammatory cytokine production, reactive oxygen species (ROS) generation, and gene expression (PGC1α, antioxidant enzymes) in macrophages.
  • Performed in vitro studies using conditioned media from MED1 KO macrophages.
  • Investigated the activation of NF-κB and STAT1 signaling pathways.

Main Results:

  • MED1 KO mice exhibited aggravated neointimal hyperplasia and increased accumulation of VSMCs and macrophages in injured arteries.
  • MED1 deficiency led to elevated proinflammatory cytokine production post-arterial injury.
  • LPS-treated MED1 KO macrophages showed increased ROS generation and reduced PGC1α and antioxidant enzyme expression.
  • Overexpression of PGC1α partially rescued the effects of MED1 deficiency.
  • Conditioned media from MED1 KO macrophages promoted VSMC proliferation and migration.
  • MED1 deficiency enhanced NF-κB and STAT1 activation, indicated by increased p-p65 and p-STAT1 levels.

Conclusions:

  • Macrophage MED1 deficiency exacerbates intimal hyperplasia and vascular inflammation.
  • MED1 deficiency promotes VSMC proliferation and migration, potentially through ROS accumulation and NF-κB/STAT1 activation.
  • These findings highlight MED1 as a critical regulator of macrophage inflammatory responses in vascular injury.

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