Purpose: This study aimed to investigate the association between paraoxonase 1 (PON1) activity phenotypes and redox status parameters, while evaluating the role of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) as a predictor of mortality and cardiovascular risk in patients undergoing chronic haemodialysis (HD).
Methods: This study cohort comprised patients with end-stage renal disease (ESRD). PON1 paraoxonase (POase) and arylesterase (ARE) activities, alongside a comprehensive redox profile, were determined spectrophotometrically. TNF-α concentrations were quantified via ELISA. PON1 phenotypes (QQ, QR, RR) were assigned using the POase/ARE ratio and the antimodal method. Survival analysis was performed using the Kaplan-Meier method.
Results: The RR phenotype was the most prevalent among HD patients (43.2%) and was significantly associated with the highest levels of oxidative stress, specifically elevated total oxidative status (TOS) and advanced oxidation protein products (AOPP) (p < 0.001). TNF-α concentrations were significantly higher in patients who died during the study compared to survivors (5.22 vs. 3.45 pg/mL, p = 0.050). Kaplan-Meier analysis confirmed that TNF-α levels > 5 pg/mL are a significant predictor of shorter survival (log-rank = 4.21, p = 0.040). Elevated TNF-α directly correlated with dyslipidemia progression and a higher atherosclerosis index.
Conclusions: The PON1 RR phenotype and elevated TNF-α concentrations (> 5 pg/mL) serve as critical biomarkers of oxidative and inflammatory status in HD patients. Their synergistic interaction contributes to accelerated atherogenesis and increased mortality, highlighting their utility in clinical risk stratification.

According to global epidemiology, non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, affecting about a quarter of the adult population worldwide. NAFLD is characterised by the accumulation of triglycerides in hepatocytes (steatosis), which can progress to non-alcoholic steatohepatitis, a more severe form of NAFLD. Oxidative stress is closely linked to the disease progression due to the activation of inflammatory pathways. The aim of this study was to identify markers of redox status that could predict the risk of developing steatosis. The study included 179 participants who underwent ultrasound examination at University Medical Centers Zemun and Zvezdara. Participants were divided into two groups: 119 patients with steatosis and 60 apparently healthy controls (control group, CG). Biochemical markers as well as markers of redox status: total oxidant status (TOS) and total antioxidant status (TAS) were determined in serum spectrophotometrically on biochemical analysers. Univariate and multivariate binary logistic regression analyses were used to test the predictions of TOS and TAS for NAFLD. Patients had higher body mass index (P<0.001), glucose (P<0.001), uric acid (P<0.001), TOS (P=0.007), and TAS (P<0.001) levels compared to CG. Univariate binary regression analysis revealed significant predictive capability of TOS and TAS for NAFLD demonstrated by the following ORs: 1.104 (1.020-1.195) (P=0.014) and 1.003 (1.001-1.004) (P<0.001), respectively. After applying multivariate binary logistic regression analyses (adjustments were made for sex and BMI), TOS and TAS kept independent significant predictive capability for NAFLD, as demonstrated by the following ORs: 1.098 (1.009-1.195) (P=0.030) and 1.002 (1.000-1.003) (P=0.026), respectively. TOS and TAS are positively associated with the risk of developing NAFLD, independent of sex and BMI. Both markers are elevated, probably because increased oxidative activity requires a stronger antioxidant defence response, which should be confirmed by a follow-up study including more participants.