TY - JOUR
T1 - Increased intracellular cyclic adenosine 3',5'-monophosphate inhibits release of tumor necrosis factor-α from human vascular tissue and cultured smooth muscle cells
AU - Zhang, Li Ming
AU - Castresana, Manuel R.
AU - Shaker, Issam J.
AU - Dalton, Martin L.
AU - Leeper-Woodford, Sandra K.
AU - Newman, Walter H.
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 1997
Y1 - 1997
N2 - Objectives: We recently reported that bacterial lipopolysaccharide stimulates release of tumor necrosis factor (TNF)-α from both human vascular tissue and cultured smooth muscle cells. In the current study, we tested the hypothesis that increased intracellular cyclic adenosine 3',5'-monophosphate (cAMP) could inhibit TNF-α release. Design: Prospective, repeated-measures analysis. Setting: Academic research laboratory. Subjects: Segments of internal mammary artery and saphenous vein from patients undergoing coronary artery bypass surgery. Measurements and Main Results: Segments of saphenous vein and internal mammary artery and confluent smooth muscle cells cultured from these vessels were incubated in the presence of 20 μg/mL bacterial lipopolysaccharide, alone or with the addition of forskolin or 8-Br-cAMP. At 0, 1, 3, 6, 18, and 24 hrs, the incubation medium was removed from vessel segments or cells and was analyzed for biologically active TNF-α, using the L929 cell cytotoxicity assay. cAMP was extracted from tissue and cells with 0.1N HCl and was analyzed by radioimmunoassay. Bacterial lipopolysaccharide stimulated the release of TNF-α from internal mammary smooth muscle cells at all time points. For example, at 6 hrs, TNF-α concentration in the medium from lipopolysaccharide-stimulated cells was 20 ± 1.6 U/mg of cell protein, compared with 0.9 ± 0.5 U/mg of cell protein in control cell medium (p < .05). Forskolin-inhibited bacterial lipopolysaccharide stimulated TNF-α release. In the presence of lipopolysaccharide and forskolin, TNF-α release at 6 hrs was 8.6 ± 1.5 U/mg of cell protein (p < .05 vs. in the presence of bacterial lipopolysaccharide alone). Bacterial lipopolysaccharide, alone, bad no effect on intracellular cAMP. Forskolin increased intracellular cAMP levels to 74.0 ± 12 pmol/mg of cell protein at 6 hrs from a control level of 7.7 ± 0.4 pmol/mg (p < .05). The 8-Br-cAMP, an agent that mimics the action of intracellular cAMP, also inhibited TNF-α release stimulated by lipopolysaccharide. Similar inhibition by forskolin and 8-Br-cAMP on TNF-α release was obtained with smooth muscle cells from saphenous vein. Finally, in tissue segments from either internal mammary artery or saphenous vein, both forskolin and 8-Br-cAMP inhibited lipopolysaccharide-stimulated TNF-α release. Conclusions: These results are consistent with the conclusion that vascular tissue, particularly the smooth muscle cell, is a source of TNF-α. Further, bacterial lipopolysaccharide-stimulated tumor TNF-α release can be inhibited by increased intracellular cAMP.
AB - Objectives: We recently reported that bacterial lipopolysaccharide stimulates release of tumor necrosis factor (TNF)-α from both human vascular tissue and cultured smooth muscle cells. In the current study, we tested the hypothesis that increased intracellular cyclic adenosine 3',5'-monophosphate (cAMP) could inhibit TNF-α release. Design: Prospective, repeated-measures analysis. Setting: Academic research laboratory. Subjects: Segments of internal mammary artery and saphenous vein from patients undergoing coronary artery bypass surgery. Measurements and Main Results: Segments of saphenous vein and internal mammary artery and confluent smooth muscle cells cultured from these vessels were incubated in the presence of 20 μg/mL bacterial lipopolysaccharide, alone or with the addition of forskolin or 8-Br-cAMP. At 0, 1, 3, 6, 18, and 24 hrs, the incubation medium was removed from vessel segments or cells and was analyzed for biologically active TNF-α, using the L929 cell cytotoxicity assay. cAMP was extracted from tissue and cells with 0.1N HCl and was analyzed by radioimmunoassay. Bacterial lipopolysaccharide stimulated the release of TNF-α from internal mammary smooth muscle cells at all time points. For example, at 6 hrs, TNF-α concentration in the medium from lipopolysaccharide-stimulated cells was 20 ± 1.6 U/mg of cell protein, compared with 0.9 ± 0.5 U/mg of cell protein in control cell medium (p < .05). Forskolin-inhibited bacterial lipopolysaccharide stimulated TNF-α release. In the presence of lipopolysaccharide and forskolin, TNF-α release at 6 hrs was 8.6 ± 1.5 U/mg of cell protein (p < .05 vs. in the presence of bacterial lipopolysaccharide alone). Bacterial lipopolysaccharide, alone, bad no effect on intracellular cAMP. Forskolin increased intracellular cAMP levels to 74.0 ± 12 pmol/mg of cell protein at 6 hrs from a control level of 7.7 ± 0.4 pmol/mg (p < .05). The 8-Br-cAMP, an agent that mimics the action of intracellular cAMP, also inhibited TNF-α release stimulated by lipopolysaccharide. Similar inhibition by forskolin and 8-Br-cAMP on TNF-α release was obtained with smooth muscle cells from saphenous vein. Finally, in tissue segments from either internal mammary artery or saphenous vein, both forskolin and 8-Br-cAMP inhibited lipopolysaccharide-stimulated TNF-α release. Conclusions: These results are consistent with the conclusion that vascular tissue, particularly the smooth muscle cell, is a source of TNF-α. Further, bacterial lipopolysaccharide-stimulated tumor TNF-α release can be inhibited by increased intracellular cAMP.
KW - Bacterial lipopolysaccharide
KW - Blood vessels
KW - Cyclic AMP
KW - Smooth muscle cells
KW - Tumor necrosis factor-α
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U2 - 10.1097/00003246-199711000-00025
DO - 10.1097/00003246-199711000-00025
M3 - Article
C2 - 9366770
AN - SCOPUS:0030730542
SN - 0090-3493
VL - 25
SP - 1855
EP - 1861
JO - Critical care medicine
JF - Critical care medicine
IS - 11
ER -