title: Serum levels of pigment epithelium-derived factor (PEDF) are positively associated with acanthosis nigricans in obese adolescents.
abstract: BACKGROUND
  Circulating pigment epithelium-derived factor, or serine protease inhibitor F1, is upregulated during adipogenesis, contributing to obesity-induced insulin resistance. Furthermore, pigment epithelium-derived factor is abundant in stage I melanosomes and has been reported to increase pigment granules and the appearance of mature melanosomes in retinal pigment epithelium. As acanthosis nigricans is a well-recognized clinical marker of insulin resistance, we hypothesized that increased pigment epithelium-derived factor might be associated with the generation of acanthosis nigricans.
  
  
  METHODS
  Acanthosis nigricans, anthropometric measurements, circulating total PEDF and metabolic profiles were assessed in 28 obese adolescents in a hospital-based obesity clinic.
  
  
  RESULTS
  Subjects with acanthosis nigricans (n = 10) showed greater plasma levels of pigment epithelium-derived factor (PEDF) than those without [geometric mean 23.55 (range 15.2-40.2) vs. 9.01 (range 5.5-18.7) μg/ml; P < 0.001]. Although pigment epithelium-derived factor was positively correlated with the homeostasis model assessment for insulin resistance (HOMA-IR) (r = 0.779, P < 0.001; 95% CI 0.573-0.892), as previously reported, for the same degree of insulin resistance, those with acanthosis nigricans exhibited a 2.1-fold (95%CI 2.0-2.3) higher level of pigment epithelium-derived factor.
  
  
  CONCLUSIONS
  While acanthosis nigricans is undoubtedly associated with insulin resistance, its appearance is not ubiquitous in patients at any given level of HOMA-IR. The higher levels of pigment epithelium-derived factor in those with acanthosis nigricans compared with those without, with similar levels of resistance, suggest that pigment epithelium-derived factor levels are associated with acanthosis nigricans.
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, UK.
authors.forename: J
authors.initials: J
authors.lastname: Galhardo
authors.forename: L P
authors.initials: LP
authors.lastname: Hunt
authors.forename: J P H
authors.initials: JP
authors.lastname: Shield
mesh_terms: D000052:Acanthosis Nigricans / Q000097:blood* / Q000235:genetics; D050156:Adipogenesis / Q000235:genetics; D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D005136:Eye Proteins / Q000097:blood* / Q000235:genetics; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D009414:Nerve Growth Factors / Q000097:blood* / Q000235:genetics; D009765:Obesity / Q000097:blood* / Q000150:complications; D015843:Serpins / Q000097:blood* / Q000235:genetics; D015854:Up-Regulation; D000515:alpha 1-Antitrypsin / Q000097:blood* / Q000235:genetics; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D005136:Eye Proteins; D009414:Nerve Growth Factors; D015843:Serpins; D000515:alpha 1-Antitrypsin; D000099174:Pigment Epithelium-Derived Factor; C043392:SERPINA1 protein, human