title: Plasma interleukin-6, tumour necrosis factor alpha and blood cytokine production in type 2 diabetes.
abstract: Type 2 diabetes is associated with increased circulating concentrations of markers of the acute-phase response and interleukin-6 (IL-6). An augmented acute-phase response may be a mechanism which explains many of the clinical and biochemical features of type 2 diabetes and its complications. We sought to confirm that circulating concentrations of the cytokine acute-phase mediators IL-6 and tumour necrosis factor alpha [TNFalpha] are elevated in type 2 diabetes, and investigated blood as a source of cytokines in type 2 diabetes. Blood samples from 20 type 2 diabetic and 17 age-matched healthy subjects were incubated in vitro for 24 hr with and without lipopolysaccharide (LPS) stimulation and secreted cytokines measured. Plasma IL-6 and TNFalpha were significantly increased in type 2 diabetes compared to normal subjects. However, basal production of IL-6 and TNFalpha in cultured diabetic blood was markedly depressed in comparison with non-diabetic samples. IL-6 and TNFalpha production was increased in blood in response to LPS, reaching similar levels in diabetic and non-diabetic subjects, though IL-6 was slightly but significantly higher in controls. We conclude that circulating levels of IL-6 and TNFalpha are increased in type 2 diabetes but there is downregulation of basal cytokine production in blood cells in type 2 diabetes. Blood has the capacity to produce cytokines in diabetes which contribute to the augmented acute-phase response, but the main source of the increased plasma IL-6 and TNFalpha concentrations may be from non-circulating cells.
authors.affiliation: Dept of Chemical Pathology, Guy's, King's and St Thomas's School of Medicine, Guy's Hospital, London, UK. j.pickup@umds.ac.uk
authors.forename: J C
authors.initials: JC
authors.lastname: Pickup
authors.forename: G D
authors.initials: GD
authors.lastname: Chusney
authors.forename: S M
authors.initials: SM
authors.lastname: Thomas
authors.forename: D
authors.initials: D
authors.lastname: Burt
mesh_terms: D000210:Acute-Phase Reaction / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000097:blood*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D019158:N-Acetylneuraminic Acid / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
chemical_list: D015850:Interleukin-6; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D019158:N-Acetylneuraminic Acid