Glucocorticoid-induced, caspase-dependent organ apoptosis early after burn injury.
Immune suppression and increased apoptotic loss of circulating lymphocytes have been reported after burn injury. However, little is known about the underlying mechanisms responsible for the increased apoptosis of lymphoid and parenchymal cells in solid organs and the role played by inflammatory mediators, such as tumor necrosis factor-alpha (TNF-alpha) and Fas ligand (FasL), as well as by glucocorticoids. To evaluate the role of endogenously produced glucocorticoids and FasL, mice subjected to a 20% steam burn were pretreated with a glucocorticoid receptor antagonist (mifepristone) or a neutralizing murine Fas fusion protein. Three and twenty-four hours after burn injury, histological analysis, caspase-3 activity, and in situ terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and phenotyping of lymphocyte populations for apoptosis were evaluated. Burn injury increased the number of apoptotic cells and caspase-3 activity in thymus and spleen, but not in other solid organs. Increased apoptosis was seen in several T and B cell populations from both thymus and spleen. Mifepristone pretreatment significantly reduced the apoptosis and caspase-3 activity after burn injury, whereas blocking FasL activity had only minimal effects. We conclude that corticosteroids, and not FasL, are primarily responsible for the increased caspase-3 activity and apoptosis in thymus and spleen cell populations early after burn injury.
Fukuzuka
K
K
Department of Surgery, University of Florida College of Medicine, Gainesville, Florida 32610, USA.
Edwards
C K
CK
Clare-Salzler
M
M
Copeland
E M
EM
Moldawer
L L
LL
Mozingo
D W
DW
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000276:immunology; D002056:Burns / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D003345:Corticosterone / Q000097:blood; D003907:Dexamethasone / Q000494:pharmacology*; D004195:Disease Models, Animal; D053222:Fas Ligand Protein; D005260:Female; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic / Q000276:immunology; D005938:Glucocorticoids / Q000494:pharmacology*; D006727:Hormone Antagonists / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D008099:Liver / Q000276:immunology / Q000473:pathology; D008168:Lung / Q000276:immunology / Q000473:pathology; D008562:Membrane Glycoproteins / Q000819:agonists / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D015735:Mifepristone / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000276:immunology / Q000473:pathology; D013950:Thymus Gland / Q000276:immunology / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D000911:Antibodies, Monoclonal; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D005938:Glucocorticoids; D006727:Hormone Antagonists; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D015735:Mifepristone; D003907:Dexamethasone; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D003345:Corticosterone