title: Structural and functional properties of deep abdominal subcutaneous adipose tissue explain its association with insulin resistance and cardiovascular risk in men.
abstract: OBJECTIVE
  Fat distribution is an important variable explaining metabolic heterogeneity of obesity. Abdominal subcutaneous adipose tissue (SAT) is divided by the Scarpa's fascia into a deep subcutaneous adipose tissue (dSAT) and a superficial subcutaneous adipose tissue (sSAT) layer. This study sought to characterize functional differences between the two SAT layers to explore their relative contribution to metabolic traits and cardiovascular risk (CVR) profile.
  
  
  METHODS
  We recruited 371 Caucasians consecutively from a local random, population-based screening project in Oxford and 25 Asian Indians from the local community. The depth of the SAT layers was determined by ultrasound (US), and adipose tissue (AT) biopsies were performed under US guidance in a subgroup of 43 Caucasians. Visceral adipose tissue (VAT) mass was quantified by dual-energy X-ray absorptiometry scan.
  
  
  RESULTS
  Male adiposity in both ethnic groups was characterized by a disproportionate expansion of dSAT, which was strongly correlated with VAT mass. dSAT depth was a strong predictor of global insulin resistance (IR; homeostatic model assessment of IR), liver-specific IR (insulin-like growth factor binding protein-1), and Framingham risk score independently of other measures of adiposity in men. Moreover, dSAT had higher expression of proinflammatory, lipogenic, and lipolytic genes and contained higher proportions of saturated fatty acids. There was increased proportion of small adipocytes in dSAT.
  
  
  CONCLUSIONS
  SAT is heterogeneous; dSAT expands disproportionally more than sSAT with increasing obesity in Caucasian males (confirmed also in Asian Indians). Its expansion is related to increased CVR independent of other adiposity measures, and it has biological properties suggestive of higher metabolic activity contributing to global IR.
authors.affiliation: Corresponding author: Fredrik Karpe, fredrik.karpe@ocdem.ox.ac.uk.
authors.forename: Kyriakoula
authors.initials: K
authors.lastname: Marinou
authors.forename: Leanne
authors.initials: L
authors.lastname: Hodson
authors.forename: Senthil K
authors.initials: SK
authors.lastname: Vasan
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Fielding
authors.forename: Rajarshi
authors.initials: R
authors.lastname: Banerjee
authors.forename: Kerstin
authors.initials: K
authors.lastname: Brismar
authors.forename: Michael
authors.initials: M
authors.lastname: Koutsilieris
authors.forename: Anne
authors.initials: A
authors.lastname: Clark
authors.forename: Matt J
authors.initials: MJ
authors.lastname: Neville
authors.forename: Fredrik
authors.initials: F
authors.lastname: Karpe
mesh_terms: D015502:Absorptiometry, Photon; D050154:Adiposity / Q000208:ethnology; D000328:Adult; D044466:Asian People; D002318:Cardiovascular Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology*; D015331:Cohort Studies; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D050152:Intra-Abdominal Fat / Q000000981:diagnostic imaging / Q000473:pathology / Q000502:physiology; D008099:Liver / Q000378:metabolism; D008297:Male; D009765:Obesity / Q000000981:diagnostic imaging / Q000208:ethnology / Q000378:metabolism / Q000473:pathology; D012307:Risk Factors; D012727:Sex Characteristics; D050507:Subcutaneous Fat, Abdominal / Q000000981:diagnostic imaging / Q000473:pathology / Q000502:physiology; D014463:Ultrasonography; D044465:White People
chemical_list: D005227:Fatty Acids