Abstract
The type III secretion system is a recently identified mechanism for protein secretion in Gram-negative bacteria. Through this secretion system, bacteria directly translocate bacterial toxins into the cytosol of eukaryotic cells under direct contact with surface of the eukaryotic cells. The translocated proteins modify the eukaryotic cell signaling to evade host immunity. The type III secretion system was recently identified in Pseudomonas aeruginosa. P. aeruginosa secretes exoenzymes directly into the cytosol of the target cell through the type III secretion system. Cytotoxic P. aeruginosa that secretes the type III cytotoxins causes acute necrosis of lung epithelium, disseminates into the systemic circulation rapidly, and induces sepsis. It suggests the type III secretion system of P. aeruginosa has a major role in the pathogenesis of acute lung injury and sepsis in P. aeruginosa pneumonia.
