Burn plasma mediates cardiac myocyte apoptosis via endotoxin.
Thermal trauma is associated with cardiac myocyte apoptosis in vivo. To determine whether cardiac myocyte apoptosis could be secondary to burn-induced cytokines or inflammatory mediators, we investigated the effects of tumor necrosis factor-alpha (TNF-alpha) and burn plasma on a murine cardiac myocyte cell line and primary culture myocytes. HL-1 cells were exposed to plasma isolated from burned or sham rats. Burn, but not sham plasma, induced significant increases in caspase-3 activity and DNA fragmentation. Similar results were obtained in primary culture rat myocytes. A dose-dependent increase in caspase-3 activity was observed when HL-1 cells were incubated with increasing concentrations of TNF-alpha. Even though TNF-alpha increased apoptosis, enzyme-linked immunosorbent assay detected no TNF-alpha in burn plasma. Burn plasma also failed to induce TNF-alpha mRNA, eliminating an autocrine mechanism of TNF-alpha secretion and binding. Also, treatment of burn plasma containing rhuTNFR:Fc failed to inhibit apoptosis. To examine the possibility that endotoxin within burn plasma might account for the apoptotic effect, burn plasma was preincubated with rBPI(21). Caspase-3 activity was reduced to control levels. These data indicate that burn plasma induces apoptosis in cardiac myocytes via an endotoxin-dependent mechanism and suggest that systemic inhibition of endotoxin may provide a therapeutic approach for treatment of burn-associated cardiac dysfunction.
Carlson
Deborah L
DL
Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
Lightfoot
Ellis
E
Bryant
Debora D
DD
Haudek
Sandra B
SB
Maass
David
D
Horton
Jureta
J
Giroir
Brett P
BP
D000818:Animals; D017209:Apoptosis; D002056:Burns / Q000097:blood*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D003470:Culture Media; D053938:DNA Fragmentation; D004731:Endotoxins / Q000097:blood* / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007118:Immunoassay; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D009206:Myocardium / Q000473:pathology*; D010949:Plasma / Q000737:chemistry; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000235:genetics / Q000494:pharmacology
D003470:Culture Media; D004731:Endotoxins; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases