title: Production of soluble tumor necrosis factor receptors by human subcutaneous adipose tissue in vivo.
abstract: To investigate in vivo adipose tissue production of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and their soluble receptors: TNF receptor type I (sTNFR-I), TNF receptor type II (sTNFR-II), and IL-6 receptor (sIL-6R), we determined arteriovenous differences in their levels across abdominal subcutaneous adipose tissue in obese subjects. Subjects had a median (interquartile range) age of 44.5 (27-51.3) yr, body mass index (BMI) of 32.9 (26. 0-46.6) kg/m(2), and %body fat of 42.5 (28.5-51.2) %. Although there was not a significant difference in the arteriovenous concentrations of TNF-alpha (P = 0.073) or sTNFR-II (P = 0.18), the levels of sTNFR-I (P = 0.002) were higher in the vein compared with artery, suggesting adipose tissue production of this soluble receptor. There was a significant arteriovenous difference in IL-6 (P < 0.001) but not in its soluble receptor (P = 0.18). There was no relationship between TNF-alpha levels and adiposity indexes (r(s) = 0.12-0.22, P = not significant); however, levels of both its soluble receptor isomers correlated significantly with BMI and %body fat (sTNFR-I r(s) = 0.42-0.72, P < 0.001; sTNFR-II r(s) = 0.36-0.65, P < 0.05- <0. 001). IL-6 levels correlated significantly with both BMI and %body fat (r(s) = 0.51, P = 0.004, and r(s) = 0.63, P < 0.001), but sIL-6R did not. In conclusion, 1) soluble TNFR-I is produced by adipose tissue, and concentrations of both soluble isoforms correlate with the degree of adiposity, and 2) IL-6, but not its soluble receptor, is produced by adipose tissue and relates to adiposity.
authors.affiliation: Centre for Diabetes and Cardiovascular Risk, University College London Medical School, London N19 3UA, United Kingdom. rmhavma@ucl.ac.uk
authors.forename: V
authors.initials: V
authors.lastname: Mohamed-Ali
authors.forename: S
authors.initials: S
authors.lastname: Goodrick
authors.forename: K
authors.initials: K
authors.lastname: Bulmer
authors.forename: J M
authors.initials: JM
authors.lastname: Holly
authors.forename: J S
authors.initials: JS
authors.lastname: Yudkin
authors.forename: S W
authors.initials: SW
authors.lastname: Coppack
mesh_terms: D000005:Abdomen; D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D017534:Radial Artery; D019947:Receptors, Interleukin-6 / Q000097:blood; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis* / Q000097:blood; D012995:Solubility; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014680:Veins
chemical_list: D015850:Interleukin-6; D019947:Receptors, Interleukin-6; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha