American journal of respiratory cell and molecular biology
-
Am. J. Respir. Cell Mol. Biol. · Nov 2011
PTEN limits alveolar macrophage function against Pseudomonas aeruginosa after bone marrow transplantation.
Hematopoietic stem cell transplant patients are susceptible to infection despite cellular reconstitution. In a murine model of syngeneic bone marrow transplantation (BMT), we previously reported that BMT mice have impaired host defense against Pseudomonas aeruginosa pneumonia due to overproduction of (PG)E(2) in lung. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is an effector in the PGE(2) signaling pathway that negatively regulates alveolar macrophage (AM) phagocytosis and bacterial killing. ⋯ However, AM phagocytosis of nonopsonized P. aeruginosa is only partially restored in the absence of PTEN after BMT. This may be related to elevated AM expression of IL-1 receptor-associated kinase (IRAK)-M, a molecule previously identified in the PGE(2) signaling pathway to inhibit AM phagocytosis of nonopsonized bacteria. These data suggest that PGE(2) signaling up-regulates IRAK-M independently of PTEN and that these molecules differentially inhibit opsonized and nonopsonized phagocytosis of P. aeruginosa.
-
Am. J. Respir. Cell Mol. Biol. · Nov 2011
Cigarette smoke targets glutaredoxin 1, increasing s-glutathionylation and epithelial cell death.
It is established that cigarette smoke (CS) causes irreversible oxidations in lung epithelial cells, and can lead to their death. However, its impact on reversible and physiologically relevant redox-dependent protein modifications remains to be investigated. Glutathione is an important antioxidant against inhaled reactive oxygen species as a direct scavenger, but it can also covalently bind protein thiols upon mild oxidative stress to protect them against irreversible oxidation. ⋯ Conversely, primary tracheal epithelial cells of mice lacking Grx1 were more sensitive to CS-induced cell death, with corresponding increases in protein S-glutathionylation. These results show that CS can modulate Grx1, not only at the expression level, but can also directly modify Grx1 itself, decreasing its activity. These findings demonstrate a role for the Grx1/S-glutathionylation redox system in CS-induced lung epithelial cell death.