Oxidative stress indexes as biomarkers of the severity in COVID-19 patients

Background: SARS-CoV-2 causes a global pandemic, with severe and critically ill COVID-19 patients often experiencing poor prognoses. Severe infection with SARS-CoV-2 is associated with oxidative stress (OS) and inflammation. Detecting markers of macromolecular damage caused by OS may provide valuable insights into disease progression. Methods: This study included 187 patients with laboratory-confirmed SARS-CoV-2 infection, categorized into non-severe, severe, and critically ill COVID-19 groups. We monitored the changes in serum indexes such as oxidized low-density lipoprotein (OxLDL), OxLDL/LDL-C ratio, advanced oxidation protein products (AOPP), 3-nitrotyrosine (3-NT), 8-hydroxydeoxyguanosine (8-OHdG), lipoprotein-associated phospholipase A₂ (Lp-PLA₂) and thromboxane B₂ (TXB₂) in patients with different clinical types. Results: 48 non-severe patients, 90 severe patients, and 49 critically ill patients were enrolled. Compared with the non-severe group, OxLDL level and OxLDL/LDL-C ratio were increased in severe COVID-19 patients and critically ill COVID-19 patients, while 3-NT and TXB₂ concentrations were lower in critically ill COVID-19 patients. Critically ill COVID-19 patients also exhibited lower concentrations of Lp-PLA₂ and a higher OxLDL/LDL-C ratio compared to severe COVID-19 patients. No significant differences were observed in AOPP and 8-OHdG concentrations. Spearman's correlation analysis revealed that CRP was associated with OxLDL, OxLDL/LDL-C ratio, AOPP, 3-NT, TXB₂, and Lp-PLA₂ (P <0.05). OxLDL was identified as an independent risk factor for progression from non-severe to severe/critically ill COVID-19. OxLDL and OxLDL/LDL-C ratio demonstrated good discriminatory value between non-severe and severe/critically ill COVID-19, with the OxLDL/LDL-C ratio also distinguishing between severe and critically ill patients. Conclusion: Patients with severe and critically ill COVID-19 exhibit elevated levels of oxidative damage to lipoproteins. OxLDL and the OxLDL/LDL-C ratio can serve as biomarkers for assessing disease severity in COVID-19 patients.