Increased oxidative stress is correlated with mitochondrial dysfunction in chagasic patients

Previously, we have shown in an experimental model of Trypanosoma cruzi infection that increased oxidative stress and antioxidant insufficiency are associated with myocardial (cellular and mitochondrial) oxidative damage and mitochondrial functional decline and might be of pathological significance in Chagas disease. In the present study, we investigated whether enhanced oxidative stress and mitochondrial functional decline are found in human chagasic patients. Our data show substantially higher plasma (two-four-fold) and mitochondrial (67%) malonylaldehyde (MDA) levels in chagasic (n = 80, group 2) compared to healthy (n = 50, group 1) subjects. Moreover, antioxidant defense was compromised in chagasic patients. Hence, we noted a 50% decline in glutathione content and losses of 31, 60, and 68% in glutathione peroxidase, superoxide dismutase (SOD), and MnSOD activities, respectively, relative to the findings in healthy controls. Further, chagasic subjects exhibited decreased mitochondrial respiratory complex (CI: 72%; CIII: 71%) activities. Nonchagasic cardiomyopathy subjects (n = 20, group 3) exhibited marginally higher plasma MDA levels compared to gp1 subjects and were not compromised in plasma antioxidant defense capacity. These data suggest that human chagasic patients sustain an antioxidant/oxidant imbalance and a mitochondrial decline of respiratory complex activities in the circulatory system. A positive correlation between increased MDA levels, MnSOD decline, and inhibition of respiratory complexes suggests that oxidative stress may contribute to mitochondrial dysfunction in chagasic patients.