Circulating factors in plasma from patients with COVID-19 cause endothelial cell dysfunction, oxidative stress and NAD+ depletion: prevention by nicotinamide riboside
Authors: Freeberg Kaitlin , Ludwig Katelyn , Seals Douglas , Rossman Matthew 
Published: May 2023

Background: Individuals infected with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), have increased risk of cardiovascular diseases (CVD). Endothelial dysfunction, characterized in part by a reduction in the vasodilatory molecule nitric oxide (NO), is a primary mechanism of CVD and has been observed in people with COVID-19. However, it is not well known if alterations in the circulating milieu (i.e., plasma) contribute to COVID-19-associated endothelial dysfunction. Moreover, the mechanisms by which circulating factors may contribute to endothelial dysfunction in COVID-19, including increased reactive oxygen species (ROS)-related oxidative stress and depletion of the key metabolic co-substrate nicotinamide adenine dinucleotide (NAD+), remain to be determined. Purpose: Here, we tested the hypotheses that circulating factors in plasma from patients with COVID-19 would cause ex vivo endothelial cell dysfunction (reduced acetylcholine-stimulated NO production), increase ROS bioactivity and decrease NAD+ levels. We also assessed whether the NAD+ precursor nicotinamide riboside (NR) would prevent endothelial cell dysfunction and oxidative stress induced by circulating factors in plasma from patients with COVID-19. Methods: Plasma samples were obtained from the University of Colorado Anschutz Medical Campus COVID-19 Biobank Specimen Repository. Samples were from men and women (age 18+ years) who were hospitalized and tested positive (+; n=34) or negative (–; n=13) for COVID-19. Human aortic endothelial cells (HAECs) in culture were exposed to 10% subject plasma, then stained with florescent probes to detect NO production (DAR-4M AM; before and 6 minutes after addition of 100μM acetylcholine), as an ex vivo model of endothelial function, and basal ROS bioactivity (CellROX), as a mechanism modulating endothelial cell function. NAD+ and NADH were measured in cells after plasma exposure using luminescence-based detection. HAECs exposed to COVID-19+ plasma also were co-incubated with 1mM NR. Results: Acetylcholine-stimulated NO production was lower (-27±12%; mean±SD; p<0.0001), and ROS bioactivity was higher (54±41%; p=0.0002), in HAECs exposed to plasma from COVID-19+ vs. COVID-19– individuals. Total NAD+ (12.4±1.8 vs. 17.7±8.0au; p=0.0013) and NAD+/NADH (4.2±1.6 vs. 5.6±1.8au; p=0.0167) were lower in HAECs exposed to plasma from COVID-19+ vs. COVID-19– individuals. However, when HAECs exposed to plasma from COVID-19+ individuals were treated with NR, acetylcholine-stimulated NO production and ROS bioactivity were not different from that of HAECs exposed to plasma from COVID-19– individuals (all p>0.05). Conclusions: These findings suggest that circulating factors promote COVID-19-related endothelial cell dysfunction, increase ROS bioactivity and lead to NAD+ depletion. Supplementation with NAD+ precursors, such as NR, may be an effective strategy to prevent endothelial dysfunction and reduce the risk of CVD with COVID-19. F31HL154782, 3R01AG061514-02S2, K01DK115524 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.