Prognostic and Pathogenic Role of Angiopoietin-1 and -2 in Pneumonia

Rationale: During pneumonia, pathogen–host interaction evokes inflammation and lung barrier dysfunction. Tie2 activation by angiopoietin-1 reduces, whereas Tie2 blockade by angiopoietin-2 increases, inflammation and permeability during sepsis. The role of angiopoietin-1/-2 in pneumonia remains unidentified.Objectives: To investigate the prognostic and pathogenic impact of angiopoietins in regulating pulmonary vascular barrier function and inflammation in bacterial pneumonia.Methods: Serum angiopoietin levels were quantified in pneumonia patients of two independent cohorts (n = 148, n = 395). Human postmortem lung tissue, pneumolysin- or angiopoietin-2–stimulated endothelial cells, isolated perfused and ventilated mouse lungs, and mice with pneumococcal pneumonia were investigated.Measurements and Main Results: In patients with pneumonia, decreased serum angiopoietin-1 and increased angiopoietin-2 levels were observed as compared with healthy subjects. Higher angiopoietin-2 serum levels were found in patie...