title: Increased 27-hydroxycholesterol plasma level in men with low high density lipoprotein-cholesterol may circumvent their reduced cell cholesterol efflux rate.
abstract: BACKGROUND
  HDL is considered the most important mechanism for the excretion of intracellular cholesterol. The liver is the only organ capable to metabolize cholesterol into bile acid. The enzymatic conversion of cholesterol to bile acid is dependent on the cytochrome P450 microsomal system which is also responsible for the generation of oxysterols. The latter's plasma concentrations may reflect the metabolic processes of specific tissues where they are generated. The objective of this study was to investigate in healthy individuals who differ according to their HDL levels the concentration of oxysterols and relate it to the HDL-dependent cell cholesterol efflux rate.
  
  
  METHODS
  24-Hydroxycholesterol, 25-hydroxycholesterol, 27-hydroxycholesterol were determined in plasma by GLC/mass spectrometry in 107 healthy subjects with low HDL (HDL-C<1.03mmol/l) and high HDL cholesterol (HDL-C>1.55mmol/l). HDL-dependent in vitro cell cholesterol efflux rate was measured in 29 cases.
  
  
  RESULTS
  No differences were found in plasma oxysterol concentrations between the Low HDL and High HDL groups. There was a significant negative correlation between HDL-C and 27-hydroxycholesterol. Plasma oxysterol concentrations were significantly lower in female than in male subjects. The Low HDL male group had higher 27-hydroxycholesterol than the High HDL male group. Cell cholesterol efflux rate was lower in Low HDL than in High HDL and related inversely with 27-hydroxycholesterol.
  
  
  CONCLUSIONS
  As compared to High HDL, Low HDL men have increased 27-hydroxycholesterol plasma level that may circumvent their reduced cell cholesterol efflux rate.
authors.affiliation: Lipids Laboratory (LIM-10), Endocrinology and Metabolism Division of Hospital das Clinicas, Faculty of Medical Sciences, University of Sao Paulo, Av. Dr. Arnaldo, 455 - room 3305, São Paulo, SP CEP 01246-000, Brazil. Electronic address: valeriasutti@gmail.com.
authors.forename: Valéria S
authors.initials: VS
authors.lastname: Nunes
authors.affiliation: Department of Clinical Pathology, School of Medical Sciences, State University of Campinas - UNICAMP, P.O. Box 6111,Campinas, São Paulo, SP CEP 13083-970, Brazil.
authors.forename: Natália B
authors.initials: NB
authors.lastname: Panzoldo
authors.affiliation: Lipids Laboratory (LIM-10), Endocrinology and Metabolism Division of Hospital das Clinicas, Faculty of Medical Sciences, University of Sao Paulo, Av. Dr. Arnaldo, 455 - room 3305, São Paulo, SP CEP 01246-000, Brazil.
authors.forename: Camila C
authors.initials: CC
authors.lastname: Leança
authors.affiliation: Department of Clinical Pathology, School of Medical Sciences, State University of Campinas - UNICAMP, P.O. Box 6111,Campinas, São Paulo, SP CEP 13083-970, Brazil.
authors.forename: Eliane S
authors.initials: ES
authors.lastname: Parra
authors.affiliation: Department of Clinical Pathology, School of Medical Sciences, State University of Campinas - UNICAMP, P.O. Box 6111,Campinas, São Paulo, SP CEP 13083-970, Brazil.
authors.forename: Vanessa S
authors.initials: VS
authors.lastname: Zago
authors.affiliation: Lipids Laboratory (LIM-10), Endocrinology and Metabolism Division of Hospital das Clinicas, Faculty of Medical Sciences, University of Sao Paulo, Av. Dr. Arnaldo, 455 - room 3305, São Paulo, SP CEP 01246-000, Brazil.
authors.forename: Eliton J
authors.initials: EJ
authors.lastname: da Silva
authors.affiliation: Lipids Laboratory (LIM-10), Endocrinology and Metabolism Division of Hospital das Clinicas, Faculty of Medical Sciences, University of Sao Paulo, Av. Dr. Arnaldo, 455 - room 3305, São Paulo, SP CEP 01246-000, Brazil.
authors.forename: Patrícia M
authors.initials: PM
authors.lastname: Cazita
authors.affiliation: Lipids Laboratory (LIM-10), Endocrinology and Metabolism Division of Hospital das Clinicas, Faculty of Medical Sciences, University of Sao Paulo, Av. Dr. Arnaldo, 455 - room 3305, São Paulo, SP CEP 01246-000, Brazil.
authors.forename: Edna R
authors.initials: ER
authors.lastname: Nakandakare
authors.affiliation: Department of Clinical Pathology, School of Medical Sciences, State University of Campinas - UNICAMP, P.O. Box 6111,Campinas, São Paulo, SP CEP 13083-970, Brazil.
authors.forename: Eliana C
authors.initials: EC
authors.lastname: de Faria
authors.affiliation: Lipids Laboratory (LIM-10), Endocrinology and Metabolism Division of Hospital das Clinicas, Faculty of Medical Sciences, University of Sao Paulo, Av. Dr. Arnaldo, 455 - room 3305, São Paulo, SP CEP 01246-000, Brazil.
authors.forename: Eder C R
authors.initials: EC
authors.lastname: Quintão
mesh_terms: D000328:Adult; D001692:Biological Transport; D008076:Cholesterol, HDL / Q000097:blood* / Q000378:metabolism; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006888:Hydroxycholesterols / Q000097:blood* / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000378:metabolism; D008297:Male
chemical_list: D008076:Cholesterol, HDL; D006888:Hydroxycholesterols; C076996:27-hydroxycholesterol
keywords: 24-Hydroxycholesterol; 25-Hydroxycholesterol; 27-Hydroxycholesterol; Cell cholesterol efflux; HDL-C