title: The pro-inflammatory cytokine IL-18 is expressed in human adipose tissue and strongly upregulated by TNFalpha in human adipocytes.
abstract: White adipocytes have been examined as a potential source of interleukin-18 (IL-18), the circulating levels of which are increased in obesity. IL-18 gene expression was evident in human subcutaneous and visceral adipose tissue, and expression occurred in mature adipocytes and the stromal-vascular fraction. Expression of the IL-18 receptor complex (IL-18Ralpha and IL-18Rbeta) and the IL-18 binding protein (IL-18BP) genes was also observed, mirroring that of IL-18. IL-18 mRNA level increased rapidly (within 2h) and dramatically (>900-fold) in response to TNFalpha in human adipocytes differentiated in culture. IL-18 protein was detected in lysates of cultured adipocytes, though not in the medium. There was a small increase in IL-18 in lysates of adipocytes treated with TNFalpha, but the protein was again undetectable in the medium. IL-18 may be part of the inflammatory cascade within adipose tissue; however, human adipocytes do not appear to secrete significant amounts of IL-18.
authors.affiliation: Obesity Biology Unit, Liverpool Centre for Nutritional Genomics, School of Clinical Sciences, University of Liverpool, University Clinical Departments, UK. i.s.wood@liverpool.ac.uk
authors.forename: I Stuart
authors.initials: IS
authors.lastname: Wood
authors.forename: Bohan
authors.initials: B
authors.lastname: Wang
authors.forename: John R
authors.initials: JR
authors.lastname: Jenkins
authors.forename: Paul
authors.initials: P
authors.lastname: Trayhurn
mesh_terms: D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism; D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism*; D001483:Base Sequence; D016207:Cytokines / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D020382:Interleukin-18 / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D016207:Cytokines; D020382:Interleukin-18; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha