title: Vitamin D modifies the associations between circulating betatrophin and cardiometabolic risk factors among youths at risk for metabolic syndrome.
abstract: Betatrophin has been recently reported to play a role in glucose homeostasis by inducing beta-cell proliferation in mice. However, studies in human are inconsistent. As a nutritionally-regulated liver-enriched factor, we hypothesize that betatrophin might be regulated by vitamin D, and ignorance of vitamin D status may explain the discrepancy in previous human studies. The aims of this study were to assess the association between circulating betatrophin and glucose homeostasis as well as other cardiometabolic variables in a cohort of youths at risk for metabolic syndrome and test the possible influence of vitamin D status on the association.
  
  
  
  559 subjects aged 14-28 years were recruited from Beijing children and adolescents metabolic syndrome study. All underwent a 2 h-oral glucose tolerance test. Serum levels of betatrophin, 25-hydroxy-vitamin D as well as adipokines including adiponectin and fibroblast growth factor 21 (FGF21) were measured by immunoassays. The relationships between betatrophin and insulin resistance, beta-cell function, other cardiometabolic variables and vitamin D status were evaluated.
  
  
  
  Participants in the highest quartile of betatrophin levels had the highest levels of total cholesterol (P < 0.001), triglyceride (P < 0.001) and low-density lipoprotein cholesterol (P < 0.001) and the lowest levels of vitamin D (P = 0.003). After stratification by vitamin D status, betatrophin in subjects with vitamin D deficiency were positively correlated with unfavorable metabolic profiles including high blood pressures, dyslipidemia and hyperglycemia, whereas betatrophin in those with higher vitamin D levels only showed negative association with fasting insulin, 2 h-insulin, and insulin resistance. In addition, adiponectin and FGF21 demonstrated the expected associations with metabolic parameters.
  
  
  
  Elevated betatrophin levels were associated with cardiometabolic risk factors in this young population, but the association was largely dependent on vitamin D status. These findings may provide valuable insights in the regulation of betatrophin and help explain the observed discrepancies in literature.
authors.affiliation: Key Laboratory of Endocrinology, Department of Endocrinology, National Health and Family Planning Commission, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China.
authors.forename: Junling
authors.initials: J
authors.lastname: Fu
authors.affiliation: Department of Endocrinology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, 10043, China.
authors.forename: Cong
authors.initials: C
authors.lastname: Hou
authors.affiliation: Key Laboratory of Endocrinology, Department of Endocrinology, National Health and Family Planning Commission, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China.
authors.forename: Lujiao
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Endocrinology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, 10043, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Feng
authors.affiliation: Key Laboratory of Endocrinology, Department of Endocrinology, National Health and Family Planning Commission, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China.
authors.forename: Ge
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
authors.forename: Mingyao
authors.initials: M
authors.lastname: Li
authors.affiliation: Division of Endocrinology, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
authors.forename: Changhong
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Endocrinology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, 10043, China. gaoshanmw@163.com.
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.affiliation: Key Laboratory of Endocrinology, Department of Endocrinology, National Health and Family Planning Commission, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China. liming@pumch.cn.|Division of Endocrinology, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA. liming@pumch.cn.
authors.forename: Ming
authors.identifier: 0000-0001-8255-0433
authors.initials: M
authors.lastname: Li
mesh_terms: D052242:Adiponectin / Q000097:blood; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000091306:Angiopoietin-Like Protein 8; D000075802:Angiopoietin-like Proteins; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D002681:China; D003430:Cross-Sectional Studies; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D005951:Glucose Tolerance Test; D006801:Humans; D007118:Immunoassay; D007333:Insulin Resistance; D008055:Lipids / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D036361:Peptide Hormones / Q000097:blood*; D011237:Predictive Value of Tests; D015995:Prevalence; D011379:Prognosis; D018570:Risk Assessment; D012307:Risk Factors; D015854:Up-Regulation; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D055815:Young Adult
chemical_list: C499918:ADIPOQ protein, human; C576683:ANGPTL8 protein, human; D052242:Adiponectin; D000091306:Angiopoietin-Like Protein 8; D000075802:Angiopoietin-like Proteins; D015415:Biomarkers; D001786:Blood Glucose; D008055:Lipids; D036361:Peptide Hormones; D014807:Vitamin D; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; C104450:25-hydroxyvitamin D
keywords: Adolescents; Betatrophin; Metabolic syndrome; Vitamin D