Turning up the heat in the lungs. A key mechanism to preserve their function

Life threatening events cause important alterations in the structure of proteins creating the urgent need of repair to preserve function and ensure survival of the cell. In eukariotic cells, an intrinsic mechanism allows them to defend against external stress. Heat shock proteins are a group of highly preserved molecular chaperones, playing a crucial role in maintaining proper protein assembly, transport and function. Stress-induced upregulation of heat shock proteins provides a unique defense system to ensure survival and function of the cell in many organ systems during conditions such as high temperature, ischemia, hypoxia, inflammation, and exposure to endotoxin or reactive oxygen species. Induction of this cellular defense mechanism prior to imposing one of these noxious insults, allows the cell/organ to withstand a subsequent insult that would otherwise be lethal, a phenomenon referred to as "thermo-tolerance" or "preconditioning". In the lung, stress-induced heat shock protein synthesis, in addition to its cyto-protective and anti-inflammatory effect, helps to preserve vectorial ion transport and alveolar fluid clearance. In this review, we describe the function of heat shock proteins in the lung, with particular emphasis on their role in the pathophysiology of experimental pulmonary edema, and their potential beneficial effects in the prevention and/or treatment of this life-threatening disease in humans.