title: Pioglitazone treatment reduces adipose tissue inflammation through reduction of mast cell and macrophage number and by improving vascularity.
abstract: OBJECTIVE
  Adipose tissue in insulin resistant subjects contains inflammatory cells and extracellular matrix components. This study examined adipose pathology of insulin resistant subjects who were treated with pioglitazone or fish oil.
  
  
  METHODS
  Adipose biopsies were examined from nine insulin resistant subjects before/after treatment with pioglitazone 45 mg/day for 12 weeks and also from 19 subjects who were treated with fish oil (1,860 mg EPA, 1,500 mg DHA daily). These studies were performed in a clinical research center setting.
  
  
  RESULTS
  Pioglitazone treatment increased the cross-sectional area of adipocytes by 18% (p = 0.01), and also increased capillary density without affecting larger vessels. Pioglitazone treatment decreased total adipose macrophage number by 26%, with a 56% decrease in M1 macrophages and an increase in M2 macrophages. Mast cells were more abundant in obese versus lean subjects, and were decreased from 24 to 13 cells/mm(2) (p = 0.02) in patients treated with pioglitazone, but not in subjects treated with FO. Although there were no changes in total collagen protein, pioglitazone increased the amount of elastin protein in adipose by 6-fold.
  
  
  CONCLUSIONS
  The PPARγ agonist pioglitazone increased adipocyte size yet improved other features of adipose, increasing capillary number and reducing mast cells and inflammatory macrophages. The increase in elastin may better permit adipocyte expansion without triggering cell necrosis and an inflammatory reaction.
authors.affiliation: The Department of Medicine, Division of Endocrinology, and the Barnstable Brown Diabetes and Obesity Center, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Spencer
authors.affiliation: The College of Public Health, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.affiliation: The Department of Medicine, Division of Endocrinology, and the Barnstable Brown Diabetes and Obesity Center, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Akosua
authors.initials: A
authors.lastname: Adu
authors.affiliation: The Department of Medicine, Division of Endocrinology, and the Barnstable Brown Diabetes and Obesity Center, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Finlin
authors.affiliation: The Department of Medicine, Division of Endocrinology, and the Barnstable Brown Diabetes and Obesity Center, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Beibei
authors.initials: B
authors.lastname: Zhu
authors.affiliation: The Department of Medicine, Division of Endocrinology, and the Barnstable Brown Diabetes and Obesity Center, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Lindsey R
authors.initials: LR
authors.lastname: Shipp
authors.affiliation: The University of Colorado Denver, Division of Endocrinology, and Eastern Colorado Veterans Health Care System, Denver, Colorado, United States of America.
authors.forename: Neda
authors.initials: N
authors.lastname: Rasouli
authors.affiliation: The College of Health Sciences, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Charlotte A
authors.initials: CA
authors.lastname: Peterson
authors.affiliation: The Department of Medicine, Division of Endocrinology, and the Barnstable Brown Diabetes and Obesity Center, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Kern
mesh_terms: D017667:Adipocytes / Q000473:pathology; D000273:Adipose Tissue / Q000187:drug effects*; D000328:Adult; D004549:Elastin / Q000096:biosynthesis; D005260:Female; D005395:Fish Oils / Q000008:administration & dosage*; D006801:Humans; D007249:Inflammation / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D007333:Insulin Resistance; D008264:Macrophages / Q000187:drug effects / Q000473:pathology; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000473:pathology; D008875:Middle Aged; D009765:Obesity / Q000188:drug therapy; D047495:PPAR gamma / Q000037:antagonists & inhibitors; D000077205:Pioglitazone; D045162:Thiazolidinediones / Q000008:administration & dosage*
chemical_list: D005395:Fish Oils; D047495:PPAR gamma; D045162:Thiazolidinediones; D004549:Elastin; D000077205:Pioglitazone