title: What distinguishes adipose tissue of severely obese humans who are insulin sensitive and resistant?
abstract: OBJECTIVE
  Despite a strong correlation between obesity and insulin resistance, 25% of severely obese (BMI >40) individuals are insulin sensitive. In this review, we will examine the factors in adipose tissue that distinguish the two groups, as well as reasons for believing the insulin-sensitive group will be less disease prone.
  
  
  RESULTS
  Obesity has been linked to the metabolic syndrome with an increase in visceral (intra-abdominal) compared to subcutaneous fat. Recent studies in which adipose tissue of insulin-sensitive and insulin-resistant patients with severe obesity were compared indicate that the insulin-resistant group is also distinguished by increases in oxidative stress and decreases in AMP-activated protein kinase (AMPK) activity. In contrast, changes in the expression of genes for SIRT1, inflammatory cytokines, mitochondrial biogenesis and function, and the two α-isoforms of AMPK showed more depot variation. Studies of how these and other changes in adipose tissue respond to bariatric surgery are still in their infancy.
  
  
  CONCLUSIONS
  Available data suggest that increases in oxidative stress, decreases in AMPK activity and SIRT1 gene expression, depot-specific changes in inflammatory, mitochondrial and other genes distinguish adipose tissue of insulin resistant from insulin-sensitive individuals with severe obesity.
authors.affiliation: Diabetes and Metabolism Unit, Section of Endocrinology, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA.
authors.forename: X Julia
authors.initials: XJ
authors.lastname: Xu
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Pories
authors.forename: Lynis G
authors.initials: LG
authors.lastname: Dohm
authors.forename: Neil B
authors.initials: NB
authors.lastname: Ruderman
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000273:Adipose Tissue / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D050110:Bariatric Surgery; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000473:pathology; D004789:Enzyme Activation; D006801:Humans; D007249:Inflammation / Q000473:pathology; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D024821:Metabolic Syndrome / Q000378:metabolism / Q000473:pathology; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D009767:Obesity, Morbid / Q000201:enzymology / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D018384:Oxidative Stress; D056564:Sirtuin 1 / Q000235:genetics / Q000378:metabolism
chemical_list: D007328:Insulin; D055372:AMP-Activated Protein Kinases; C447939:SIRT1 protein, human; D056564:Sirtuin 1