title: Cardiotrophin-1 is expressed in adipose tissue and upregulated in the metabolic syndrome.
abstract: Adipose tissue is a target for cardiotrophin-1 (CT-1), a cytokine member of the IL-6 family of cytokines that is involved in cardiac growth and dysfunction. However, it is unknown whether adipocytes are a source of CT-1 and whether CT-1 is overexpressed in diseases characterized by increased fat depots [i.e., the metabolic syndrome (MS)]. Thus this work aimed 1) to test whether adipose tissue expresses CT-1 and whether CT-1 expression can be modulated and 2) to compare serum CT-1 levels in subjects with and without MS diagnosed by National Cholesterol Education Program Adult Treatment Panel III criteria. Gene and protein expression of CT-1 was determined by real-time RT-PCR, ELISA, and Western blotting. CT-1 expression progressively increased, along with differentiation time from preadipocyte to mature adipocyte in 3T3-L1 cells. CT-1 expression was enhanced by glucose in a dose-dependent manner in these cells. mRNA and protein CT-1 expression was also demonstrated in human adipose biopsies. Immunostaining showed positive staining in adipocytes. Finally, increased CT-1 serum levels were observed in patients with MS compared with control subjects (127 +/- 9 vs. 106 +/- 4 ng/ml, P < 0.05). Circulating levels of CT-1 were associated with glucose levels (r = 0.2, P < 0.05). Taken together, our data suggest that adipose tissue can be recognized as a source of CT-1, which could account for the high circulating levels of CT-1 in patients with MS.
authors.affiliation: Division of Cardiovascular Sciences, Center for Applied Medical Research, University of Navarra, Avda Pío XII 55, 31008 Pamplona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Natal
authors.forename: María Antonia
authors.initials: MA
authors.lastname: Fortuño
authors.forename: Patricia
authors.initials: P
authors.lastname: Restituto
authors.forename: Antonio
authors.initials: A
authors.lastname: Bazán
authors.forename: Immaculada
authors.initials: I
authors.lastname: Colina
authors.forename: Javier
authors.initials: J
authors.lastname: Díez
authors.forename: Nerea
authors.initials: N
authors.lastname: Varo
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000502:physiology*; D000273:Adipose Tissue / Q000166:cytology / Q000502:physiology*; D000328:Adult; D000368:Aged; D000818:Animals; D001706:Biopsy; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism / Q000503:physiopathology; D012333:RNA, Messenger / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; C092073:cardiotrophin 1