TEK and Sepsis: Sepsis down-regulates the expression of Angpt-1, Tek, and KDR in systemic tissues at the transcriptional level, and Angpt-1, Tek, KDR corresponds to Ang-1, Tie2, and VEGFR2 or Flk-1.When these proteins are down-regulated, permeability of pulmonary capillary endothelial is increased and then lung injury develops (94).The alveolar epithelium, composed of alveolar type I and type II cells, is primarily responsible for gas exchange and alveolar fluid clearance in the lung.