Superoxide dismutase 3 dysregulation in a murine model of neonatal lung injury

Bronchopulmonary dysplasia (BPD), a common chronic respiratory disease that occurs after premature birth, is believed to be secondary to oxidative damage from hyperoxia and inflammation, which leads to impaired alveolar formation and chronic lung dysfunction. We hypothesized that extracellular superoxide dismutase (SOD)3, an antioxidant uniquely targeted to the extracellular matrix (ECM) and alveolar fluid, might have a different response (down-regulation) to hyperoxic injury and recovery in room air (RA), thereby contributing to the persistent airspace injury and inflammation. We used a murine BPD model using postnatal hyperoxia (O2) (4 or 5 d) followed by short-term recovery (14 d) in RA, which mimics the durable effects after injury during alveolar development. This was associated with significantly increased mRNA expression for antioxidant genes mediated by nuclear factor erythroid 2-related factor (Nrf2) in the O2 (n = 4) versus RA group (n = 5). SOD3, an Nrf2-independent antioxidant, was significantly reduced in the O2-exposed mice compared with RA. Immunohistochemistry revealed decreased and disrupted SOD3 deposition in the alveolar ECM of O2-exposed mice. Furthermore, this distinct hyperoxic antioxidant and injury profile was reproducible in murine lung epithelial 12 cells exposed to O2. Overexpression of SOD3 rescued the injury measures in the O2-exposed cells. We establish that reduced SOD3 expression correlates with alveolar injury measures in the recovered neonatal hyperoxic lung, and SOD3 overexpression attenuates hyperoxic injury in an alveolar epithelial cell line. Such findings suggest a candidate mechanism for the pathogenesis of BPD that may lead to targeted interventions.

Tuberculosis in patients with HIV infection who receive corticosteroids for presumed Pneumocystis carinii pneumonia

To determine if the use of corticosteroids for presumed Pneumocystis carinii pneumonia exacerbated undiagnosed tuberculosis or increased the likelihood of reactivation tuberculosis, we reviewed medical records of 144 hospitalized HIV-infected patients who received antipneumocystis therapy. Ninety-four patients (Group C) received corticosteroids and 50 patients (Group NC) did not. One hundred and thirty-seven patients (97%) had acid-fast stains and mycobacterial cultures performed. Group C and Group NC were similar in ethnicity, distribution of HIV risk factors and CD4 cell count. Eight (9%) Group C patients and seven (14%) Group NC patients had culture-proven tuberculosis during their hospitalization. After a median followup of 16 mo after discharge, one (2%) Group C patient and two (4%) Group NC patients developed tuberculosis. Only one patient in Group C died of tuberculosis, despite receiving antituberculosis therapy. We conclude that the use of corticosteroids for presumed P. carinii pneumonia does not increase morbidity from undiagnosed tuberculosis or increase the frequency of reactivation tuberculosis.