Tumour necrosis factor-alpha (TNF-alpha) plays a key role in orchestrating the complex events involved in inflammation and immunity, Accordingly, TNF-alpha has been implicated in a wide range of autoimmune and infecti...
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Tumour necrosis factor-alpha (TNF-alpha) plays a key role in orchestrating the complex events involved in inflammation and immunity, Accordingly, TNF-alpha has been implicated in a wide range of autoimmune and infectious diseases, but also in conditions such as obesity and insulin resistance. The regulation of TNF-alpha expression in man is indicated to be partly genetically determined. We therefore screened a 1263 bp section of the proximal promoter of the TNF-alpha gene for common genetic variants affecting the transcriptional activity of the gene. Here we report the characterization of a common functional polymorphism in the promoter region of the TNF-alpha gene, a C-->A substitution at position -863, Electromobility shift assays provided evidence for a distinct difference in the binding of monocytic and hepatic nuclear factors to the -863C and -863A alleles, The rare -863A allele was associated with 31% lower transcriptional activity (P < 0.001) in chloramphenicol acetyltransferase (CAT) reporter gene studies in human hepatoblastoma (HepG2) cells, indicating that the -863C/A polymorphism influences the basal rate of transcription of the TNF-alpha gene in vitro, Allele frequencies were 0.83/0.17 amongst 254 apparently healthy men of Swedish origin, aged 35-50 years. In 156 men, the -863C/A polymorphism was associated with the serum TNF-alpha concentration, carriers of the rare A allele having a significantly lower TNF-alpha level (P < 0.05). It is concluded that the common -863C/A polymorphism in the promoter region of the TNF-alpha gene is functional in vitro in monocytic and hepatic cells and influences the serum TNF-alpha concentration in vivo in healthy middle-aged men.
In a double-blind, placebo-controlled, randomized study, 10 healthy men received either a single dose of 480 mu g granulocyte colony-stimulating factor (G-CSF) or saline. Blood taken from the volunteers was stimulated...
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In a double-blind, placebo-controlled, randomized study, 10 healthy men received either a single dose of 480 mu g granulocyte colony-stimulating factor (G-CSF) or saline. Blood taken from the volunteers was stimulated with 10 mu g/mL endotoxin and released cytokines were measured by enzyme-linked immunosorbent assay. Expression of G-CSF receptors on leukocytes was examined by flow cytometry and reverse transcriptase-polymerase chain reaction. Functional activity of these receptors was tested by challenging isolated leukocyte populations to release cytokines with endotoxin in the presence of G-CSF. The G-CSF treatment attenuated the release of the proinflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-12, IL-1 beta, and interferon (IFN)-gamma in ex vivo lipopolysaccharide (LPS)-stimulated whole blood, In blood from untreated volunteers the presence of G-CSF in vitro also attenuated the LPS-stimulated release of these cytokines. G-CSF in vitro also attenuated TNF-alpha release from elutriation-purified monocytes, In the presence of 10 ng/mL recombinant TNF-alpha, the attenuation of LPS-inducible lFN-gamma release by G-CSF was blunted in whole blood. However, G-CSF had no such effect on IFN-gamma release from isolated lymphocytes stimulated with anti-CDS or a combination of TNF-alpha and IL-12, G-CSF receptor expression was detected in human neutrophils and monocytes but not in lymphocytes by means of RT-PCR as well as flow cytometry, These results indicate that G-CSF receptors expressed on monocytes are functional in modulating monokine release. We conclude that the attenuation of IFN-gamma release from lymphocytes is not a direct effect of G-CSF on these cells but is rather due to the inhibition of monocytic IL-12 and TNF-alpha release by G-CSF. (C) 2000 by The American Society of Hematology.
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