COVID-19 is associated with long-term vascular complications, but the underlying mechanisms remain incompletely understood. During infection, NADhomeostasis becomes dys-regulated, with excessive NADconsumption and enhanced catabolic flux through nicotinamide methylation pathways. This imbalance leads to NADdepletion accompanied by accumulation of pyridone metabolites, including N-methyl-2-pyridone-5-carboxamide (Met2PY) and N-methyl-4-pyridone-3-carboxamide (Met4PY). These derivatives have been linked to oxidative stress, endothelial dysfunction, and cardiovascular risk, yet their role in long COVID remains unclear. We enrolled 26 post-COVID patients with persistent cardiovascular symptoms and 8 healthy controls. Serum concentrations of Met2PY and Met4PY were quantified by LC/MS. High-sensitivity C-reactive protein (hsCRP), tumor necrosis factor-alpha (TNFα), interleukin-10 (IL-10), and soluble intercellular adhesion molecule-1 (sICAM-1) were measured to assess systemic inflammation and endothelial activation. Statistical analyses included group comparisons and correlation analyses. We observed significantly elevated Met2PY levels (0.770 ± 0.08 vs. 0.389 ± 0.09 µmol/l) and a trend toward increased Met4PY (0.095 ± 0.01 vs. 0.055 ± 0.01 µmol/l) in post-COVID patients compared with controls. Both metabolites positively correlated with hsCRP. Importantly, Met2PY was associated with an unfavorable cytokine profile (higher TNFα/IL-10 ratio) and increased sICAM-1 levels, whereas no such associations were observed for Met4PY. Persistent dysregulation of NADmetabolism and accumulation of pyridone metabolites, particularly Met2PY, are associated with markers of chronic endothelial activation and inflammation in long COVID. These findings support the potential utility of Met2PY as a biomarker to identify patients at higher risk for endothelial dysfunction and cardiovascular events, enabling more personalized risk stratification and follow-up. + + + +
Long Covid