Cell-specific expression of manganese superoxide dismutase protein in the lungs of patients with respiratory distress syndrome, chronic lung disease,or persistent pulmonary hypertension

The developmental profile of manganese superoxide dismutase (MnSOD) and its regulation in hyperoxia vary between species. We hypothesized that MnSOD i ncreases in human lung in response to oxygen treatment, although this respo nse could be restricted to certain cell types and depend on gestational age . Therefore, the cell-specific expression of pulmonary immunoreactive MnSOD protein was investigated during development, and in patients with respirat ory distress syndrome (RDS), chronic lung disease (CLD), or persistent pulm onary hypertension (PPHN). Throughout ontogenesis, all cell types expressed MnSOD, but the most intens e positivity was found in bronchiolar epithelium and (pre-) type-II pneumoc ytes. MnSOD protein did not increase during development. The MnSOD staining pattern in arterial endothelium was more intense in RDS patients than in a ge-matched controls, but this may be related to induction of MnSOD by incre ased blood flow rather than by oxygen. MnSOD expression in other cell types of RDS, CLD, or PPHN patients did not differ from that in age-matched cont rols. We conclude that, in terms of mitochondrial enzymatic superoxide scavenging capacity, preterm infants are not more vulnerable than term infants to oxy gen-induced lung injury at physiological oxygen concentrations. However, th e inability to induce MnSOD in response to oxygen treatment may result in a poor outcome. (C) 2001 Wiley-Liss, Inc.