title: Dietary strawberries increase the proliferative response of CD3/CD28-activated CD8⁺ T cells and the production of TNF-α in lipopolysaccharide-stimulated monocytes from obese human subjects.
abstract: Obesity increases the risk of developing bacterial and viral infections compared with normal weight. In a 7-week double-blind, randomised, cross-over trial, twenty obese volunteers (BMI between 30 and 40 kg/m²) were fed freeze-dried strawberry powder or strawberry-flavoured placebo preparations to determine the effects of dietary strawberries on immune function. Blood was collected at six time points during the study and peripheral blood mononuclear cells (PBMC) were isolated at each time point and activated with CD3 plus CD28 antibodies (T-lymphocyte activation) or lipopolysaccharide (LPS, monocyte activation). Interferon-γ, TNF-α, IL-4 and IL-10 were measured in supernatants from the activated T cells. Supernatants from the activated monocytes were analysed for the production of TNF-α, IL-1β, IL-6 and IL-8. PBMC were pre-stained with PKH (Paul Karl Horan) dye and activated with CD3 plus CD28 antibodies to determine the proliferative responses of CD4⁺ and CD8⁺ T-lymphocytes by flow cytometry. To detect global changes in gene expression, microarray analysis was performed on LPS- and vehicle-treated PBMC from two subjects before and after the strawberry intervention. No difference was observed for the production of T-cell cytokines between the intervention groups. The production of TNF-α was increased in the supernatants from LPS-activated PBMC in the group consuming strawberries compared with the placebo. A modest increase in the proliferation of the CD8⁺ T-lymphocyte population was observed at 24 h post-activation. These data suggest that dietary strawberries may increase the immunological response of T-lymphocytes and monocytes in obese people who are at greater risk for developing infections.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Western Human Nutrition Research Center, 430 West Health Sciences Drive, Davis, CA 95616, USA.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Zunino
authors.forename: David H
authors.initials: DH
authors.lastname: Storms
authors.forename: Tammy L
authors.initials: TL
authors.lastname: Freytag
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Mackey
authors.forename: Ling
authors.initials: L
authors.lastname: Zhao
authors.forename: Julia S
authors.initials: JS
authors.lastname: Gouffon
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Hwang
mesh_terms: D000328:Adult; D015992:Body Mass Index; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation; D002478:Cells, Cultured; D018592:Cross-Over Studies; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D031985:Fragaria; D005638:Fruit; D005786:Gene Expression Regulation; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D009765:Obesity / Q000178:diet therapy* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D016207:Cytokines; D007155:Immunologic Factors; D014409:Tumor Necrosis Factor-alpha