Lactoferrin and Thioredoxin in Rheumatoid Arthritis Are Associated with Fibrinogen but Not with Other Acute Phase Proteins.

Rheumatoid arthritis (RA) is one of the most common chronic autoimmune diseases which global prevalence is approximately 0.3-2%. Numerous studies provide evidence that the elevated levels of reactive oxygen species (ROS) contribute to the pathogenesis and progression of RA. In response to redox imbalance, several intrinsic antioxidant defence mechanisms are activated to counteract oxidative stress and scavenge ROS. The aim of the present study is to analyse whether the levels of lactoferrin and thioredoxin, two proteins which are part of the antioxidant defence of the body, are associated with fibrinogen and other acute phase proteins such as CRP and ferritin in RA. Serum lactoferrin, thioredoxin, ferritin, and CRP levels were measured using ELISA. Significant positive correlations of lactoferrin and thioredoxin with fibrinogen were observed in RA patients, r = 0.394, < 0.0001 and r = 0.410, = 0.002, respectively. These positive correlations were also observed in females, r = 0.375, < 0.0001 and r = 0.447, = 0.001, in the subgroup of patients with DAS28 < 5.1, r = 0.689, < 0.0001 and r = 0.604, = 0.001 and in the subgroup of patients with normal CRP, r = 0.488, < 0.0001 and r = 0.414, = 0.005, respectively. These findings help clarify the pathogenetic interplay between oxidative stress, inflammation, and coagulation in RA and indicate the need for further studies to elucidate the potential of lactoferrin and thioredoxin as biomarkers that capture pathological disease changes.