title: Sex-specific effects of CNTF, IL6 and UCP2 polymorphisms on weight gain.
abstract: The human proteins ciliary neurotrophic factor (CNTF) and interleukin-6 (IL6) and their receptors share structural homology with leptin and its receptor. In addition, uncoupling protein-2 (UCP2) has been shown to participate the regulation of leptin on food intake. All three proteins are active in the hypothalamus. Experiments have shown that CNTF and IL6, like leptin, can influence body weight in humans and animals, while the effect of UCP2 is not consistent. In a Dutch general population (n=545) we investigated associations of CNTF (null G/A, rs1800169), IL6 (174 G/C, rs1800795) and UCP2 (A55V, rs660339 and del/ins) polymorphisms with weight gain using interaction graphs and logistic regression analysis. The average follow-up period was 6.9 years. Individuals who gained weight (n=264) were compared with individuals who remained stable in weight (n=281). In women the CNTF polymorphism (odds ratio (OR)=2.15, 95%CI: 1.27-3.64, p=0.004) and in men the IL6 polymorphism by itself (OR=2.26, 95%CI: 1.08-4.75, p=0.03) or in combination with the CNTF polymorphism, were associated with weight gain. Furthermore, CNTF and IL6 polymorphisms in interaction with UCP2 polymorphisms had similar strong effects on weight gain in women and men, respectively. All observed effects were statistically shown to be independent of serum leptin level. These results are incorporated in a biological model for weight regulation with upstream effects of CNTF and IL6, and downstream effects of UCP2. The results of this study suggest a novel mechanism for weight regulation that is active in both women and men, but strongly influenced by sex.
authors.affiliation: Department of Human Biology, Maastricht University, PO Box 616 6200 MD Maastricht, The Netherlands. geert.heidema@wur.nl
authors.forename: A Geert
authors.initials: AG
authors.lastname: Heidema
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Caroline T M
authors.initials: CT
authors.lastname: van Rossum
authors.forename: Edith J M
authors.initials: EJ
authors.lastname: Feskens
authors.forename: Jolanda M A
authors.initials: JM
authors.lastname: Boer
authors.forename: Freek G
authors.initials: FG
authors.lastname: Bouwman
authors.forename: Pieter
authors.initials: P
authors.lastname: Van't Veer
authors.forename: Edwin C M
authors.initials: EC
authors.lastname: Mariman
mesh_terms: D000328:Adult; D000886:Anthropometry / Q000379:methods; D016009:Chi-Square Distribution; D020934:Ciliary Neurotrophic Factor / Q000235:genetics*; D015331:Cohort Studies; D016001:Confidence Intervals; D019277:Entropy; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D007473:Ion Channels / Q000235:genetics*; D020738:Leptin / Q000097:blood; D008297:Male; D024101:Mitochondrial Proteins / Q000235:genetics*; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012737:Sex Factors; D000071246:Uncoupling Protein 2; D015430:Weight Gain / Q000235:genetics*; D055815:Young Adult
chemical_list: D020934:Ciliary Neurotrophic Factor; C508600:IL6 protein, human; D015850:Interleukin-6; D007473:Ion Channels; D020738:Leptin; D024101:Mitochondrial Proteins; C000604389:UCP2 protein, human; D000071246:Uncoupling Protein 2