title: Stimulation of interleukin-6 release by interleukin-1beta from isolated human adipocytes.
abstract: The secretion of interleukin-6 (IL-6) is modulated by immune, hormonal and metabolic stimuli in a cell-specific manner. We investigated the effect of cytokines, TNFalpha and IL-1beta, and insulin on IL-6 release from human adipocytes and peripheral blood cells (PBC). Adipocytes released IL-6 constitutively (after 5 h: 5.64 [1.61-15.30]pg ml(-1), after 10 h: 15.95 [2.34-45.59]pg ml(-1), p = 0.007), while PBC secretion did not change significantly over this period. LPS stimulated IL-6 secretion in PBC after 5 h but was without effect on adipocytes. TNFalpha and insulin induced IL-6 production from PBC, but had no effect on adipocytes. IL-1beta, however, induced a substantial increase in IL-6 release in adipocytes and PBC (all p < 0.05). Adipose tissue production of IL-1beta was assessed in vivo by measuring arterio-venous differences across the subcutaneous abdominal adipose bed. Net release of IL-1beta was not observed, suggesting that under basal conditions there is no detectable release of this cytokine into the circulation from this depot. In conclusion (1) PBC demonstrate regulated IL-6 release, while the adipocyte release has a large constitutive component; (2) immune modulators, such as LPS, TNFalpha and IL-1beta, all induce PBC IL-6 release, but only IL-1beta stimulates adipocyte release. Though IL-1beta is not an endocrine signal from adipose tissue, it is an autocrine/paracrine stimulator of IL-6 release from human adipocytes.
authors.affiliation: Adipokines and Metabolism Research Group, Department of Medicine, Royal Free and University College London Medical School, 48 Riding House Street, London W1W 7EY, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Flower
authors.forename: Rosaire
authors.initials: R
authors.lastname: Gray
authors.forename: Jonathan
authors.initials: J
authors.lastname: Pinkney
authors.forename: Vidya
authors.initials: V
authors.lastname: Mohamed-Ali
mesh_terms: D017667:Adipocytes / Q000378:metabolism*; D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D001769:Blood / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007375:Interleukin-1 / Q000097:blood* / Q000378:metabolism*; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000097:blood* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D016207:Cytokines; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides