title: Intracellular monocyte and serum cytokine expression is modulated by exhausting exercise and cold exposure.
abstract: This study tested the hypothesis that exercise elicits monocytic cytokine expression and that prolonged cold exposure modulates such responses. Nine men (age, 24.6 +/- 3.8 y; VO(2 peak), 56.8 +/- 5.6 ml. kg(-1). min(-1)) completed 7 days of exhausting exercise (aerobic, anaerobic, resistive) and underwent three cold, wet exposures (CW). CW trials comprised </=6 h (six 1-h rest-work cycles) exposure to cold (5 degrees C, 20 km/h wind) and wet (5 cm/h rain) conditions. Blood samples for the determination of intracellular and serum cytokine levels and circulating hormone concentrations were drawn at rest (0700), after exercise (approximately 1130), and after CW (~2000). Whole blood was incubated with (stimulated) or without (spontaneous) lipopolysaccharide (LPS; 1 microgram/ml) and stained for CD14 monocyte surface antigens. Cell suspensions were stained for intracellular cytokine expression and analyzed by flow cytometry. The proportion of CD14(+) monocytes exhibiting spontaneous and stimulated intracellular expression of interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha increased after exercise, but these cells produced less IL-1beta and TNF-alpha after CW when CW was preceded by exhausting exercise. Serum cytokine concentrations followed a parallel trend. These findings suggest that blood monocytes contribute to exercise-induced cytokinemia and that cold exposure can differentially modulate cytokine production, upregulating expression of IL-6 and IL-1 receptor antagonist but downregulating IL-1beta and TNF-alpha. The cold-induced changes in cytokine expression appear to be linked to enhanced catecholamine secretion associated with cold exposure.
authors.affiliation: Defence and Civil Institute of Environmental Medicine, Toronto, M3M 3B9, Ontario M5S 1A1 Canada.
authors.forename: S G
authors.initials: SG
authors.lastname: Rhind
authors.forename: J W
authors.initials: JW
authors.lastname: Castellani
authors.forename: I K
authors.initials: IK
authors.lastname: Brenner
authors.forename: R J
authors.initials: RJ
authors.lastname: Shephard
authors.forename: J
authors.initials: J
authors.lastname: Zamecnik
authors.forename: S J
authors.initials: SJ
authors.lastname: Montain
authors.forename: A J
authors.initials: AJ
authors.lastname: Young
authors.forename: P N
authors.initials: PN
authors.lastname: Shek
mesh_terms: D000328:Adult; D003080:Cold Temperature; D016207:Cytokines / Q000097:blood*; D004837:Epinephrine / Q000097:blood; D005434:Flow Cytometry; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007375:Interleukin-1 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D007958:Leukocyte Count; D018950:Lipopolysaccharide Receptors / Q000032:analysis; D008297:Male; D009000:Monocytes / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D009638:Norepinephrine / Q000097:blood; D005082:Physical Exertion / Q000502:physiology*; D012044:Regression Analysis; D013312:Stress, Physiological / Q000276:immunology / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016207:Cytokines; D007375:Interleukin-1; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D014409:Tumor Necrosis Factor-alpha; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine