title: Balanced caloric macronutrient composition downregulates immunological gene expression in human blood cells-adipose tissue diverges.
abstract: Cardiovascular disease, obesity, and type 2 diabetes are conditions characterized by low-grade systemic inflammation, strongly influenced by lifestyle, but the mechanisms that link these characteristics are poorly understood. Our first objective was to investigate if a normocaloric diet with a calorically balanced macronutrient composition influenced immunological gene expression. Findings regarding the suitability of blood as biological material in nutrigenomics and gene expression profiling have been inconclusive. Our second objective was to compare blood and adipose tissue sample quality in terms of adequacy for DNA-microarray analyses, and to determine tissue-specific gene expression patterns. Blood and adipose tissue samples were collected for gene expression profiling from three obese men before, during, and after a 28-day normocaloric diet intervention where each meal contained an approximately equal caloric load of macronutrients. Time series analyses of blood gene expression revealed a cluster of downregulated genes involved in immunological processes. Blood RNA quality and yield were satisfactory, and DNA-microarray analysis reproducibility was similar in blood and adipose tissue. Gene expression correlation between blood and adipose tissue varied according to gene function, and was especially low for genes involved in immunological and metabolic processes. This suggests that diet composition is of importance in inflammatory processes in blood cells. The findings also suggest that a systems biology approach, in which tissues are studied in parallel, should be employed to fully understand the impact of dietary challenges on the human body.
authors.affiliation: Department of Biology, Norwegian University of Science and Technology NTNU, Trondheim 7491, Norway. berit.johansen@bio.ntnu.no
authors.forename: Hans-Richard
authors.initials: HR
authors.lastname: Brattbakk
authors.forename: Ingerid
authors.initials: I
authors.lastname: Arbo
authors.forename: Siv
authors.initials: S
authors.lastname: Aagaard
authors.forename: Inge
authors.initials: I
authors.lastname: Lindseth
authors.forename: Ann Kristin Hjelle
authors.initials: AK
authors.lastname: de Soysa
authors.forename: Mette
authors.initials: M
authors.lastname: Langaas
authors.forename: Bård
authors.initials: B
authors.lastname: Kulseng
authors.forename: Fedon
authors.initials: F
authors.lastname: Lindberg
authors.forename: Berit
authors.initials: B
authors.lastname: Johansen
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D004032:Diet; D015536:Down-Regulation; D002149:Energy Intake; D020869:Gene Expression Profiling; D006801:Humans; D007107:Immune System / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009693:Nucleic Acid Hybridization; D009765:Obesity / Q000097:blood* / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis