Abstract
Bacterial pneumonia is the most common cause of acute respiratory distress syndrome (ARDS), characterized by disrupted pulmonary endothelial barrier function, hyperinflammation, and impaired alveolar epithelial fluid clearance. ARDS has a high mortality rate and no proven pharmacological treatments, stressing the need for new targeted therapies. The TIP peptide, mimicking the lectin-like domain of TNF, directly binds to the α subunit of the epithelial Na+ channel, expressed in both alveolar epithelial and capillary endothelial cells, and may increase lung endothelial barrier function and alveolar fluid clearance during bacterial infection. This study tested these potential therapeutic mechanisms of the TIP peptide in a clinically relevant preparation of the ex vivo-perfused human lung injured by Streptococcus pneumoniae. Therapeutic administration of the TIP peptide reduced pulmonary barrier permeability to protein and lung edema formation, increased alveolar edema fluid clearance, and produced an antiinflammatory effect in the airspaces with reductions in IL-6 and IL-8 levels. Additionally, the TIP peptide reduced the translocation of bacteria into the circulation. These findings establish 3 mechanisms of benefit with the TIP peptide to reduce injury in the human lung and support the clinical relevance as a potential therapeutic for pneumococcal bacterial pneumonia.