Molecular Markers of Endothelial Dysfunction in Post-COVID Prediabetes: A Focus on NOS3 Gene Expression and Pro-Inflammatory Cytokine Profiles

Background: Prediabetes, marked by early insulin resistance and chronic low-grade inflammation, is closely linked to endothelial dysfunction and increased cardiovascular risk. Post-COVID-19 recovery may intensify this risk due to persistent vascular inflammation and endothelial damage. This study investigates the relationship between NOS3 gene expression and key pro-inflammatory cytokines (IL-6, IL-18, TNF-α, IL-1β) in post-COVID prediabetic individuals to identify early molecular markers of endothelial malfunction and inform preventive strategies. Methods and Results: A case-control study was conducted with 120 participants (60 post-COVID prediabetics and 60 healthy controls). Blood samples were analyzed for biochemical markers and cytokine levels using ELISA, while NOS3 gene expression was quantified using RT-PCR (normalized to GAPDH via the 2 ^−ΔΔCt method). Data were analyzed using Stata 17.0. Results indicated significantly elevated levels of IL-6, IL-18, IL-1β, TNF-α, and NOS3 expression in post-COVID prediabetics, suggesting heightened inflammation and endothelial activation. ROC analysis revealed IL-6 and TNF-α as strong discriminatory markers. A positive correlation was observed between NOS3 expression and all cytokines. Logistic regression showed that IL-18, IL-6, and TNF-α were significant independent predictors of NOS3 dysregulation, while IL-1β lost significance after adjustment. Conclusion: This study highlights a clear association between elevated pro-inflammatory cytokines and NOS3 overexpression in post-COVID prediabetes, reflecting a compensatory endothelial response to inflammation. IL-18 emerged as the strongest independent predictor, supporting the potential of NOS3 as an early biomarker for endothelial stress and emphasizing the role of inflammation in cardiometabolic risk post-COVID-19.