title: Regulation of thrombospondin-1 expression in alternatively activated macrophages and adipocytes: role of cellular cross talk and omega-3 fatty acids.
abstract: Thrombospondin-1 (TSP-1) expression in human adipose positively correlates with body mass index and may contribute to adipose dysfunction by activating transforming growth factor-β and/or inhibiting angiogenesis. Our objective was to determine how TSP-1 is regulated in adipocytes and polarized macrophages using a coculture system and to determine whether fatty acids, including the ω-3 fatty acid docosahexaenoic acid (DHA), regulate TSP-1 expression. Coculture of M1, M2a or M2c macrophages with adipocytes induced TSP-1 gene expression in adipocytes (from 2.4- to 4.2-fold, P<.05), and adipocyte coculture induced TSP-1 gene expression in M1 and M2c macrophages (M1: 8.6-fold, M2c: 26-fold; P<.05). TSP-1 protein levels in the shared media of adipocytes and M2c cells were also strongly induced by coculture (>10-fold, P<.05). DHA treatment during the coculture of adipocytes and M2c macrophages potently inhibited the M2c macrophage TSP-1 mRNA level (97% inhibition, P<.05). Adipocyte coculture induced interleukin (IL)-10 expression in M2c macrophages (10.1-fold, P<.05), and this increase in IL-10 mRNA expression was almost completely blocked with DHA treatment (96% inhibition, P<.05); thus, IL-10 expression closely paralleled TSP-1 expression. Since IL-10 has been shown to regulate TSP-1 in other cell types, we reduced IL-10 expression with siRNA in the M2c cells and found that this caused TSP-1 to be reduced in response to adipocyte coculture by 60% (P<.05), suggesting that IL-10 regulates TSP-1 expression in M2c macrophages. These results suggest that supplementation with dietary ω-3 fatty acids could potentially be beneficial to adipose tissue in obesity by reducing TSP-1 and fibrosis.
authors.affiliation: Department of Medicine, Division of Endocrinology, University of Kentucky, Lexington, KY 40536, USA. bfinlin@uky.edu
authors.forename: Brian S
authors.initials: BS
authors.lastname: Finlin
authors.forename: Beibei
authors.initials: B
authors.lastname: Zhu
authors.forename: Catherine P
authors.initials: CP
authors.lastname: Starnes
authors.forename: Robert E
authors.initials: RE
authors.lastname: McGehee
authors.forename: Charlotte A
authors.initials: CA
authors.lastname: Peterson
authors.forename: Philip A
authors.initials: PA
authors.lastname: Kern
mesh_terms: D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D050154:Adiposity / Q000187:drug effects; D015992:Body Mass Index; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D004032:Diet; D004281:Docosahexaenoic Acids / Q000494:pharmacology*; D005355:Fibrosis / Q000503:physiopathology; D006801:Humans; D016753:Interleukin-10 / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D009765:Obesity / Q000188:drug therapy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019700:Thrombospondin 1 / Q000235:genetics* / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D019700:Thrombospondin 1; D016753:Interleukin-10; D004281:Docosahexaenoic Acids
keywords: ADHASC; Adipocyte; CTGF; DHA; Docosahexaenoic acid; ECM; EPA; FFA; IL-10; Macrophage; PMA; TLR; TSP-1; Thrombospondin-1; Toll like receptor; adult-derived human adipose stem cell; connective tissue growth factor; docosahexaenoic acid; eicosapentaenoic acid; extracellular matrix; free fatty acid; phorbal myristate acetate; thrombospondin-1