Pericytes and T Cells in Lung Injury and Fibroproliferation

The respiratory system is essentially an external organ, constantly exposed to the external environment. As such, it is in contact with any number of antigens and chemical agents that can injure the upper (nasal cavity, pharynx, and larynx) or lower (trachea, bronchi, and lungs) respiratory tract [1]. Injuries to the lung parenchyma are particularly harmful, as the parenchyma is the site of gas (oxygen and carbon dioxide) exchange. Acute or chronic injuries to the lung result in acute or chronic hypoxemic or hypercapnic respiratory failure, respectively. While there are several structural and pathologic mechanisms that contribute to respiratory failure, some lung injuries result in a progressive fibroproliferative response that leads to respiratory failure and death.