Impairment of erythrocyte redox status and hemoglobin alterations across disease severity in chronic obstructive pulmonary disease

Systemic hypoxemia in chronic obstructive pulmonary disease (COPD) is traditionally attributed to impaired pulmonary gas exchange. However, alterations in erythrocyte redox regulation may further compromise oxygen transport.
The objective of this study is to evaluate the erythrocyte electron-transport and oxygen-transport functions at different stages of COPD.
This single-center cross-sectional study included 150 clinically stable COPD patients (mild – n = 54, moderate – n = 59, severe – n = 37) and 40 healthy controls. Erythrocyte cytochrome C and cytochrome b₅ content, NADH- and NADPH-dependent reductase activities, glucose-6-phosphate dehydrogenase activity, 2,3-diphosphoglycerate levels, hemoglobin fractions, and blood gas parameters were measured. COPD patients demonstrated reduced erythrocyte cytochrome C and cytochrome b₅ content and decreased glucose-6-phosphate dehydrogenase activity, accompanied by increased reductase activities (all – p < 0.001). Oxyhemoglobin levels declined, while deoxyhemoglobin and methemoglobin levels increased with disease severity. Elevated 2,3-diphosphoglycerate levels suggested partial compensation. Blood gas analysis revealed progressive hypoxemia and metabolic disturbance. It has been posited that progressive impairment of erythrocyte redox status and hemoglobin alterations may contribute to impaired systemic oxygen delivery in COPD beyond pulmonary dysfunction.

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