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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2003;23:e65.)
© 2003 American Heart Association, Inc.

Letters to the Editor

TSH Stimulates IL-6 Secretion from Adipocytes in Culture

Andrea Bell; AnneMarie Gagnon; Alexander Sorisky

Department of Medicine and of Biochemistry, Microbiology & Immunology, University of Ottawa, Ottawa Health Research Institute, Ottawa, Canada

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

Adipocytes secrete interleukin-6 (IL-6), a pro-atherogenic cytokine.^1–3 However, regulation of adipocyte IL-6 secretion remains largely unknown. Adipocytes express thyroid-stimulating hormone (TSH) receptors.^4–6 Because subclinical hypothyroidism, characterized by an elevated TSH level, is an independent cardiovascular disease (CVD) risk factor,⁷ we hypothesized that TSH stimulates adipocyte IL-6 secretion.

3T3-F442A (Dr. Howard Green, Harvard University, Boston, Mass)⁸ and 3T3-L1 (ATCC) cells were grown in DMEM with 10% calf serum in 35-mm dishes. Confluent 3T3-F442A preadipocytes were differentiated in control medium (DMEM with 10% fetal bovine serum [FBS]) with 1 µM insulin for 8 days.⁹ Confluent 3T3-L1 preadipocytes were differentiated with control medium with 1 µmol/L insulin over 8 days, and 0.25 µmol/L dexamethasone and 0.5 mmol/L isobutylmethylxanthine (IBMX) present for the first 2 days.⁹ Subcutaneous abdominal adipose tissue was obtained from 9 patients (4 male, 5 female) undergoing elective abdominal surgery (Ottawa Hospital Research Ethics Committee approval). Human preadipocytes were isolated by collagenase digestion and serial filtrations. Cells were seeded in 24-well plates at 3x10⁴ cells/cm² in DMEM with 20% FBS, grown to confluence, and then placed in serum-free differentiation medium.¹⁰ Differentiation medium was DMEM:Ham’s F12 (1:1), 33 µmol/L biotin, 17 µmol/L pantothenate, 10 µg/mL transferrin, 0.2 nM triiodothyronine, 1 µmol/L insulin, and 1 µmol/L cortisol. For the first 4 days, 0.5 mmol/L IBMX, 25 nM dexamethasone, and 5 µmol/L troglitazone (Roche) were added. The medium was then replaced every 3 days for 2 weeks, and 70% differentiation was observed.

Differentiated 3T3-F442A and 3T3-L1 adipocytes were placed . . . [Full Text of this Article]