The effect of an mRNA vaccine against COVID-19 on endothelial function and arterial stiffness.

To fight the COVID-19 pandemic, messenger RNA (mRNA) vaccines were the first to be adopted by vaccination programs worldwide. We sought to investigate the short-term effect of mRNA vaccine administration on endothelial function and arterial stiffness. Thirty-two participants (mean age 37 ± 8 years, 20 men) who received the BNT162b2 mRNA COVID-19 vaccine were studied in three sessions in a sequence-randomized, sham-controlled, assessor-blinded, crossover design. The primary outcome was endothelial function (assessed by brachial artery flow-mediated dilatation (FMD)), and the secondary outcomes were aortic stiffness (evaluated with carotid-femoral pulse wave velocity (PWV)) and inflammation (measured by high-sensitivity C-reactive protein (hsCRP) in blood samples). The outcomes were assessed prior to and at 8 h and 24 h after the 1st dose of vaccine and at 8 h, 24 h, and 48 h after the 2nd dose. There was an increase in hsCRP that was apparent at 24 h after both the 1st dose (-0.60 [95% confidence intervals [CI]: -1.60 to -0.20], p = 0.013) and the 2nd dose (maximum median difference at 48 h -6.60 [95% CI: -9.80 to -3.40], p < 0.001) compared to placebo. The vaccine did not change PWV. FMD remained unchanged during the 1st dose but decreased significantly by 1.5% (95% CI: 0.1% to 2.9%, p = 0.037) at 24 h after the 2nd dose. FMD values returned to baseline at 48 h. Our study shows that the mRNA vaccine causes a prominent increase in inflammatory markers, especially after the 2nd dose, and a transient deterioration of endothelial function at 24 h that returns to baseline at 48 h. These results confirm the short-term cardiovascular safety of the vaccine.

Association of gut microbiota composition and their metabolites with subclinical atheromatosis: A systematic review.

Study objective: The present systematic review investigates the hypothesis that specific components of the intestinal microbiome and/or their metabolites are associated with early stages of subclinical arterial damage (SAD). Design: Based on the MOOSE criteria, we conducted a systematic review of the literature (Scopus, Medline) investigating the potential association between gut microbiota and the most widely applied arterial biomarkers of SAD. Participants: All studies included individuals without established cardiovascular disease, either with or without SAD. Intervention: No interventions were made. Main outcome measures: Association between exposure (components/metabolites of microbiota) and outcome (presence of SAD). Results: Fourteen articles met the predefined criteria. Due to the large heterogeneity, their meta-analysis was not possible. Our review revealed (a) two studies on endothelial dysfunction, out of which one found an inverse relation between plasma trimethylamine N-oxide levels and FMD and the other did not substantiate a statistically significant correlation with RHI. (b) Twelve studies on atheromatosis, assessed as intimal-medial thickness (IMT), coronary artery calcium (CAC) and arterial plaque, of which, seven studies showed statistically significant associations (negative or positive depending on the microorganism or microbiota metabolite) with IMT, one study revealed significant associations with coronary artery calcium, while one showed absence of correlation and four studies reported statistically significant correlations with arterial plaque. (c) Three studies on arterial stiffness (pulse wave velocity - PWV) with two of them concluding in statistically significant association while the third study did not. Some articles investigated multiple of the correlations described and therefore, belonged to more than one section. Conclusion: Evidence of both positive and inverse associations of gut microbiota composition and their metabolites with different types of SVD has been found. However the small number and heterogeneity of available studies cannot allow to confirm or disprove the hypothesis.