Impairment of macrophage survival by NaCl: implications for early pulmonary inflammation in cystic fibrosis.
Inflammation, characterized by the presence of proinflammatory chemokines and neutrophils, is a hallmark of early airway disease in infants with cystic fibrosis (CF), although the underlying mechanisms remain poorly defined. In this study, we evaluated the role of NaCl and the ensuing hyperosmolar effect on tumor necrosis factor (TNF)-alpha signaling and apoptosis in macrophages. Incubation of mouse macrophages with NaCl activated p38(mapk) and the p46(jnk) and p54(jnk) c-jun NH(2)-terminal kinase isoforms, but not p42(mapk/erk2) or Akt. Similar results were obtained with sorbitol, suggesting a general response to hyperosmolarity. Strikingly, the activation of p42(mapk/erk2) and Akt by TNF-alpha was also inhibited in the presence of NaCl. Because the activation of p42(mapk/erk2) and Akt has been associated with survival responses, we investigated the effect of NaCl on macrophage apoptosis. The results indicated a synergistic increase in apoptosis when macrophages were exposed to TNF-alpha in the presence of NaCl compared with stimulation with TNF-alpha alone or NaCl alone. Furthermore, pharmacological inhibition of p42(mapk/erk2) and Akt mimicked the effect of NaCl. Collectively, these findings indicate that modest elevations in NaCl differentially regulate the activation of mitogen-activated protein kinases and Akt and potentiate macrophage apoptosis. We speculate that augmentation of macrophage apoptosis in CF airways may result in decreased clearance of neutrophils and in deficiencies in the elimination of common CF pathogens.
Kerby
Gwendolyn S
GS
Program in Cell Biology, Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206, USA.
Cottin
Vincent
V
Accurso
Frank J
FJ
Hoffmann
Fukun
F
Chan
Edward D
ED
Fadok
Valerie A
VA
Riches
David W H
DW
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D003550:Cystic Fibrosis / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000276:immunology; D008264:Macrophages / Q000166:cytology* / Q000276:immunology; D051379:Mice; D008809:Mice, Inbred C3H; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D009997:Osmotic Pressure; D011014:Pneumonia / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012965:Sodium Chloride / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology; D048051:p38 Mitogen-Activated Protein Kinases
D002867:Chromones; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009025:Morpholines; D011518:Proto-Oncogene Proteins; D014409:Tumor Necrosis Factor-alpha; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D012965:Sodium Chloride; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one