Introduction: Endothelial microparticles (EMP) are membrane vesicles, with a characteristic diameter of 0.1-1.0μ, shed by endothelial cells during cellular activation or apoptosis. EMP are associated with cardiovascular disease and risk factors, but data are lacking on the relations of EMP with subclinical vascular brain injury.
Methods: We studied 487 individuals (mean age 66.9±8.8 years, 55% women) from the Framingham Offspring Cohort, who were free from clinical stroke. CD31+/CD41- EMP were identified and quantified using flow cytometry. Silent cerebral infarcts (SCI) were quantified as parenchymal lesions on brain MRI >3mm in size with characteristics of previous infarcts. Logistic regression models were used to investigate cross-sectional associations of EMP levels with prevalent SCI. We tested for interaction between EMP levels and statin use in their relationship with SCI.
Results: SCI was observed in 49 (10%) participants. Figure 1 displays results of the logistic regression analysis. Circulating CD31+/CD41- EMP levels were inversely associated with SCI, adjusting for age, sex, and time interval between blood draw and brain MRI (OR 0.90 [0.82-0.98], p=0.016). Similar results were observed when adjusting for additional vascular risk factors. We observed an interaction between statin use and EMP levels in their association with SCI. There was an inverse association (OR 0.76 [0.64-0.89], p=0.001) among statin users and no association among non-statin users.
Conclusions: In our analysis of the relationship of CD31+/CD41- EMP with SCI, in a well-defined community cohort, we observed an inverse association of higher EMP levels, primarily in participants on statins. Our data question whether constitutive or induced release of EMP, associated with a pleiotropic effect of statin medication, might mitigate vascular risk factor exposure and reduce risk of SCI. Further studies are needed to determine the associations of EMP with SCI and clinical stroke.