Heme inhibits human neutrophil apoptosis: involvement of phosphoinositide 3-kinase, MAPK, and NF-kappaB.
High levels of free heme are found in pathological states of increased hemolysis, such as sickle cell disease, malaria, and ischemia reperfusion. The hemolytic events are often associated with an inflammatory response that usually turns into chronic inflammation. We recently reported that heme is a proinflammatory molecule, able to induce neutrophil migration, reactive oxygen species generation, and IL-8 expression. In this study, we show that heme (1-50 microM) delays human neutrophil spontaneous apoptosis in vitro. This effect requires heme oxygenase activity, and depends on reactive oxygen species production and on de novo protein synthesis. Inhibition of ERK and PI3K pathways abolished heme-protective effects upon human neutrophils, suggesting the involvement of the Ras/Raf/MAPK and PI3K pathway on this effect. Confirming the involvement of these pathways in the modulation of the antiapoptotic effect, heme induces Akt phosphorylation and ERK-2 nuclear translocation in neutrophils. Futhermore, inhibition of NF-kappa B translocation reversed heme antiapoptotic effect. NF-kappa B (p65 subunit) nuclear translocation and I kappa B degradation were also observed in heme-treated cells, indicating that free heme may regulate neutrophil life span modulating signaling pathways involved in cell survival. Our data suggest that free heme associated with hemolytic episodes might play an important role in the development of chronic inflammation by interfering with the longevity of neutrophils.
Arruda
Maria Augusta
MA
Departamento de Farmacologia, Instituto de Biologia, Universidade do Estado do Rio de Janeiro, Brazil.
Rossi
Adriano G
AG
de Freitas
Marta S
MS
Barja-Fidalgo
Christina
C
Graça-Souza
Aurélio V
AV
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D017209:Apoptosis / Q000187:drug effects*; D002352:Carrier Proteins / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D003864:Depression, Chemical; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006418:Heme / Q000494:pharmacology*; D006419:Heme Oxygenase (Decyclizing) / Q000037:antagonists & inhibitors / Q000378:metabolism; D006461:Hemolysis; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D016209:Interleukin-8 / Q000096:biosynthesis; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008665:Metalloporphyrins / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects*; D010084:Oxidation-Reduction; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D011524:Protoporphyrins / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst / Q000187:drug effects; D051996:Transcription Factor RelA; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
D002352:Carrier Proteins; D003513:Cycloheximide; D004791:Enzyme Inhibitors; D006418:Heme; D006419:Heme Oxygenase (Decyclizing); D020672:I-kappa B Proteins; D016209:Interleukin-8; D008665:Metalloporphyrins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011500:Protein Synthesis Inhibitors; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D011524:Protoporphyrins; D017382:Reactive Oxygen Species; D051996:Transcription Factor RelA; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; C494819:BAD protein, human; C494811:BCL2L1 protein, human; C032628:tin protoporphyrin IX; C494918:AKT1 protein, human