Protocatechuic Acid Inhibits Vulnerable Atherosclerotic Lesion Progression in Older Apoe-/- Mice

J Nutr. 2020 May 1;150(5):1167-1177. doi: 10.1093/jn/nxaa017.


Background: Normalization of arterial inflammation inhibits atherosclerosis. The preventive role for protocatechuic acid (PCA) in early-stage atherosclerosis is well recognized; however, its therapeutic role in late-stage atherosclerosis remains unexplored.

Objective: We investigated whether PCA inhibits vulnerable atherosclerosis progression by normalizing arterial inflammation.

Methods: Thirty-wk-old male apolipoprotein E-deficient (Apoe-/-) mice with vulnerable atherosclerotic lesions in the brachiocephalic artery were fed the AIN-93G diet alone (control) or supplemented with 0.003% PCA (wt:wt) for 20 wk. Lesion size and composition, IL-1β, and NF-κB in the brachiocephalic arteries, and serum lipid profiles, oxidative status, and proinflammatory cytokines (e.g., IL-1β, monocyte chemoattractant protein-1, and serum amyloid A) were measured. Moreover, the effect of PCA on the inflammation response was evaluated in efferocytic macrophages from C57BL/6J mice.

Results: Compared with the control treatment, dietary PCA supplementation significantly reduced lesion size (27.5%; P < 0.05) and also improved lesion stability (P < 0.05) as evidenced by increased thin fibrous cap thickness (31.7%) and collagen accumulation (58.3%), reduced necrotic core size (37.6%) and cellular apoptosis (73.9%), reduced macrophage accumulation (45.1%), and increased vascular smooth muscle cell accumulation (51.5%). Moreover, PCA supplementation inhibited IL-1β expression (53.7%) and NF-κB activation (64.4%) in lesions. However, PCA supplementation did not change serum lipid profiles, total antioxidant capacity, and inflammatory cytokines. In efferocytic macrophages, PCA at 0.5 and 1 μmol/L inhibited Il1b/IL-1β mRNA (27.2-46.5%) and protein (29.2-49.6%) expression and NF-κB activation (67.0-80.3%) by upregulation of MER proto-oncogene tyrosine kinase (MERTK) and inhibition of mitogen-activated protein kinase 3/1 (MAPK3/1). Strikingly, the similar pattern of the MERTK and MAPK3/1 changes in lesional macrophages of mice after PCA intervention in vivo was recapitulated.

Conclusion: PCA inhibits vulnerable lesion progression in mice, which might partially be caused by normalization of arterial inflammation by upregulation of MERTK and inhibition of MAPK3/1 in lesional macrophages.

Keywords: apoptosis; inflammation; macrophage; protocatechuic acid; vulnerable atherosclerotic lesions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents
  • Apolipoproteins E / deficiency*
  • Apolipoproteins E / genetics
  • Apolipoproteins E / physiology
  • Atherosclerosis / pathology*
  • Atherosclerosis / prevention & control*
  • Cells, Cultured
  • Dietary Supplements
  • Disease Models, Animal
  • Gene Expression / drug effects
  • Hydroxybenzoates / administration & dosage*
  • Interleukin-1beta / metabolism
  • Macrophages, Peritoneal / drug effects
  • Macrophages, Peritoneal / physiology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitogen-Activated Protein Kinase 1 / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase 1 / physiology
  • Mitogen-Activated Protein Kinase 3 / antagonists & inhibitors
  • NF-kappa B / metabolism
  • c-Mer Tyrosine Kinase / genetics
  • c-Mer Tyrosine Kinase / physiology


  • Anti-Inflammatory Agents
  • Apolipoproteins E
  • Hydroxybenzoates
  • Interleukin-1beta
  • NF-kappa B
  • protocatechuic acid
  • Mertk protein, mouse
  • c-Mer Tyrosine Kinase
  • Mapk1 protein, mouse
  • Mapk3 protein, mouse
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3