Exploring the relationship between oxidative stress status and inflammatory markers during primary Sjögren's syndrome: A new approach for patient monitoring.

Introduction: Primary Sjögren's syndrome (pSS) is a chronic inflammatory disease primarily affects exocrine glands dysfunction. Oxidative stress (OS) is a phenomenon occurring as a result of an imbalance between the generation of free radicals and antioxidant defense system. Hence, we aimed to establish the status of OS and inflammatory response according to the pSS disease activity index. In this context, we investigated malondialdehyde (MDA), and antioxidant enzymes during pSS. The possible association between MDA and nitric oxide (NO) levels and between MDA and some pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-33).

Methods: The study has been conducted on 53 pSS patients. The antioxidant enzymes, represented by glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD), were estimated by a colorimetric activity kit. Whereas, MDA value was assessed by measuring thiobarbituric acid reactive substances. Moreover, pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-33) and NO were respectively quantified by enzyme-linked immunosorbent assays (ELISA) and the modified Griess.

Results: Interestingly, we report a notable reduction in our pSS patients' antioxidant enzyme activity, while NO, MDA and proinflammatory cytokines values were significantly increased. pSS patients with higher disease activity had much stronger increases in NO and MDA levels. No significant difference was assessed in CRP level. Additionally, substantial significant correlations between plasmatic NO and MDA levels and between MDA, NO and IL-1β, IL-6, TNF-α cytokines were reported. However, no significant association was found between NO, MDA and IL-33 concentrations.

Conclusion: Collectively, our data showed altered oxidant-antioxidant balance in pSS patients. MDA, NO, IL-1β, IL-6, TNF-α seem to be good indicators in monitoring disease activity. Oxidative stress was closely related to inflammation in pSS. Exploiting this relationship might provide valuable indicators in the follow-up and prognosis of pSS with a potential therapeutic value.