Causal associations of serum matrix metalloproteinase-8 level with ischaemic stroke and ischaemic stroke subtypes: a Mendelian randomization study

Eur J Neurol. 2021 Aug;28(8):2543-2551. doi: 10.1111/ene.14878. Epub 2021 May 14.


Background and purpose: Elevated serum matrix metalloproteinase-8 (MMP-8) concentrations are associated with high risk of vascular disease, but the causality remains unclear. A two-sample Mendelian randomization (MR) study was performed to examine the causal effect of serum MMP-8 concentrations on the risk of ischaemic stroke, ischaemic stroke subtypes and coronary artery disease.

Methods: Ten independent single-nucleotide polymorphisms related to serum MMP-8 concentrations were identified as instrumental variables from a genome-wide association study of 6049 European subjects. Genetic association estimates for ischaemic stroke were obtained from the Multiancestry Genome-wide Association Study of Stroke consortium with 446,696 European individuals. The inverse-variance weighted method was applied to assess the causal associations of serum MMP-8 with ischaemic stroke and its subtypes in the main analysis.

Results: No significant causal association was observed for MMP-8 levels with total ischaemic stroke, large artery stroke or cardioembolic stroke. Genetically determined 1 - unit higher log-transformed serum MMP-8 concentration was associated with an increased risk of small vessel stroke (odds ratio 1.25; 95% confidence interval 1.12-1.39; p < 0.001). In secondary analysis, a similar adverse impact was reported for MMP-8 on coronary artery disease (odds ratio 1.05; 95% confidence interval 1.01-1.10; p = 0.017). Sensitivity analyses further confirmed the relationship between serum MMP-8 level and small vessel stroke and coronary artery disease. Mendelian randomization Egger regression showed no evidence of pleiotropic bias.

Conclusions: High serum MMP-8 concentrations were causally associated with increased risks of small vessel stroke and coronary artery disease. The mechanism underlying the effect of serum MMP-8 on the vascular system requires further investigation.

Keywords: MMP-8; biomarkers; coronary artery disease; ischaemic stroke; vascular disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brain Ischemia* / genetics
  • Genome-Wide Association Study
  • Humans
  • Ischemic Stroke*
  • Matrix Metalloproteinase 8 / blood*
  • Mendelian Randomization Analysis
  • Polymorphism, Single Nucleotide
  • Risk Factors
  • Stroke* / genetics


  • MMP8 protein, human
  • Matrix Metalloproteinase 8