Butyrate induces apoptosis in murine macrophages via caspase-3, but independent of autocrine synthesis of tumor necrosis factor and nitric oxide.
We demonstrated that 4 mM butyrate induces apoptosis in murine peritoneal macrophages in a dose- and time-dependent manner as indicated by studies of cell viability, flow cytometric analysis of annexin-V binding, DNA ladder pattern and the determination of hypodiploid DNA content. The activity of caspase-3 was enhanced during macrophage apoptosis induced by butyrate and the caspase inhibitor z-VAD-FMK (100 microM) inhibited the butyrate effect, indicating the major role of the caspase cascade in the process. The levels of butyrate-induced apoptosis in macrophages were enhanced by co-treatment with 1 microg/ml bacterial lipopolysaccharide (LPS). However, our data indicate that apoptosis induced by butyrate and LPS involves different mechanisms. Thus, LPS-induced apoptosis was only observed when macrophages were primed with IFN-gamma and was partially dependent on iNOS, TNFR1 and IRF-1 functions as determined in experiments employing macrophages from various knockout mice. In contrast, butyrate-induced macrophage apoptosis was highly independent of IFN-gamma priming and of iNOS, TNFR1 and IRF-1 functions.
Ramos
M G
MG
Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
Rabelo
F L A
FL
Duarte
T
T
Gazzinelli
R T
RT
Alvarez-Leite
J I
JI
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D002087:Butyrates / Q000494:pharmacology*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002470:Cell Survival; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000032:analysis / Q000096:biosynthesis*; D010537:Peritoneum / Q000166:cytology; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000096:biosynthesis*
D000590:Amino Acid Chloromethyl Ketones; D002087:Butyrates; D061945:Caspase Inhibitors; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D009569:Nitric Oxide; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases