Role of iRhom2 in intestinal ischemia-reperfusion-mediated acute lung injury.

Intestinal ischemia-reperfusion (I/R) may cause acute systemic and lung inflammation. However, the detailed mechanism of this inflammatory cascade has not been fully elucidated. Inactive rhomboid protein 2 (iRhom2) is essential for the maturation of TNF-α converting enzyme (TACE), which is required for TNF-α secretion. We evaluated the role of iRhom2 in a mouse model of intestinal I/R using iRhom2 knockout (KO) and wild-type (WT) mice. Lung injury following intestinal I/R was significantly attenuated in iRhom2 KO mice compared with WT mice. After intestinal I/R, lungs from iRhom2 KO mice showed significantly lower myeloperoxidase (MPO) activity and markedly reduced cell apoptosis associated with a decreased level of active caspase 3 and decreased TUNEL staining compared with lungs from WT mice. TNF-α levels were elevated in the serum and lungs of WT mice with intestinal I/R and significantly reduced in iRhom2 KO mice with intestinal I/R. iRhom2 may play a critical role in the pathogenesis of acute lung injury (ALI) after intestinal I/R and thus may be a novel therapeutic target for ALI after intestinal I/R injury.