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 TGF-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 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<0.05), and adipocyte coculture induced TSP-1 gene expression in M1 and M2c macrophages (M1:8.6-fold; M2c 26-fold, P<0.05). TSP-1 protein levels in the shared media of adipocytes and M2c cells was also strongly induced by coculture (>10 fold, P<0.05). DHA treatment during the coculture of adipocytes and M2c macrophages potently inhibited theM2c macrophage TSP-1 mRNA level (97% inhibition, P<0.05). Adipocyte coculture induced IL-10 expression in M2c macrophages (10.1-fold, P<0.05), and this increase in IL-10 mRNA expression was almost completely blocked with DHA treatment (96% inhibition, P<0.05); 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<0.05), 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.

Interaction of thrombospondin1 and CD36 contributes to obesity-associated podocytopathy

“…Moreover, saturated FFA stimulated TSP1 expression in macrophages [33]. Therefore, we determined whether FFA could stimulate TSP1 expression in podocytes.…”

Increasing Adipocyte Lipoprotein Lipase Improves Glucose Metabolism in High Fat Diet-induced Obesity

“…Gene Expression-Gene expression was determined by real time reverse transcriptase polymerase chain reaction, as described previously (20), except that a Qiagen lipid kit (74804) was used. Standard curves were made from a pool of the cDNA, and gene expression was normalized to 18 S. This allows for the measurement of relative changes in gene expression within the indicated experiment.…”

Docosahexaenoic acid attenuates Western diet-induced hepatic fibrosis in Ldlr mice by targeting the TGFβ-Smad3 pathway

“…Feeding mice the WD + O diet induced multiple components associated with TGF ␤ signaling, including several TGF ␤ subtypes (TGF ␤ 1-3), a TGF ␤ receptor subunit (TGF ␤ -R2), and two thrombospondins (Thbs1 and Thbs2). Thbs1 and Thbs2 are expressed in macrophage, whereas Thbs2 is also expressed in endothelial cells ( 65,66 ). Thbs1 induces TGF ␤ Ϫ dependent and TGF ␤ Ϫ independent fi brosis.…”

“…The WD induces expression of several hepatic collagen subtypes ( Fig. 3 ) as well as enzymes involved in ECM remodeling, including metalloproteases (Mmp1a, Mmp2, and Mmp13), protease inhibitors [Timp1 and Timp2, serine protease inhibitors (serpine1 suppress Thbs1 expression in adipose tissue ( 65 ). Thbs2, in contrast, attenuates fi brosis ( 67,68 ).…”