SO4= uptake and oxidative stress in erythrocytes from systemic sclerosis patients with interstitial lung disease.

The rate constant for SO4= uptake, accounting for Band 3 protein efficiency in erythrocytes, is a good tool to detect oxidative stress effects. The aim of the present study was to verify whether SO4= uptake is affected by Systemic Sclerosis (SSc), a chronic multisystemic connective tissue disease associated to oxidative stress. Blood samples were withdrawn from 15 healthy controls and 20 SSc patients, with same age and stage of disease. Twelve of SSc patients were affected by interstitial lung disease (SSc-ILD), while 8 had no HRTC sign of pulmonary fibrosis. Malondialdehyde (MDA) plasma levels, measured to quantify oxidative stress, were significantly higher in SSc patients than healthy controls, with the highest values in SSc-ILD patients, whereas the rate constant for SO4= uptake, detected by a turbidimetric method, was significantly lower in SSc patients than in healthy controls, with no difference between SSc-ILD and SSc without ILD. We may hence conclude that: i) oxidant/antioxidant imbalance in SSc affects erythrocytes, namely at Band 3 protein level; ii) Band 3 protein from both groups of patients is affected at the same extent, in spite of the different MDA plasma levels; iii) the rate constant for SO4= uptake measurement is useful in monitoring erythrocytes homeostasis in oxidative stress-related pathologies; iv) Band 3 protein could be considered as a candidate for drug development, currently involving antioxidants compounds.