Intracellular HSP72 expression in monocyte subsets between trained and untrained individuals during exertional heat stress

Par Conseil national de recherches du Canada

Auteur	Rechercher : Selkirk, Glen A.; Rechercher : McLellan, Tom M.; Rechercher : Wright, Heather E.; Rechercher : Rhind, Shawn G.; Rechercher : Jacobs, I.
Format	Texte, Allocution
Conférence	53rd Annual American College of Sports Medicine Conference (ACSM), May 31 - June 3, 2006, Denver, Colorado, USA
Résumé	Monocytes are a heterogeneous population with two distinct subsets, regular (CD14Bright+) and proinflammatory (CD14Dim+). Little is known about the intracellular heat shock protein (HSP) 72 expression in these subsets during exertional heat stress. PURPOSE: The purpose of this study was to examine the impact of exertional heat stress on HSP72 expression in CD14⁺ monocyte subsets in trained and untrained individuals. METHODS: Maximum oxygen consumption expressed per kg of lean body mass (LBM) and activity history was used to divide subjects into trained (TR, n=8, VO₂peak = 68 ± 2 mL·kgLBM⁻-min⁻¹) and untrained (UT, n=6, VO₂peak = 49 ± 1 mL·kgLBM⁻ ¹-min⁻ ¹) groups. Subjects walked at 4.5 km-h¹ with 2% elevation in a climatic chamber (40°C; 30% R.H.) wearing military biological and chemical protective clothing until specific end-point criteria were attained. Venous blood samples were collected at baseline, rectal temperatures of 38.0°C, 38.5°C, 39.0°C and at exhaustion. Whole blood samples were analyzed immediately by flow cytometry for spontaneous intracellular HSP72 immunofluorecence staining in monocyte subsets CD14Dim+ and CD14Bright+. Similar analyses were performed at baseline and exhaustion following in vitro heat shock (42°C, 2 hr). RESULTS: Total CD14⁺ and CD14⁺Bright counts (×10⁹cells/L) were significantly increased in TR at exhaustion compared to UT, whereas UT subjects levels of CD14⁺Dim were significantly increased compared to TR at 39.0°C and exhaustion (0.12 ± 0.04 vs. 0.076 ± 0.004 ×10⁹cells). Percentages of CD14+ cells positive for intracellular HSP72 expression were significantly elevated in TR compared to UT during in vivo heat stress; however, following in-vitro heat shock (42°C, 2hr), only CD14Dim+ subset was significantly elevated compared to UT. CONCLUSIONS: These findings reveal an increased level of proinflammatory (CD14Dim+) monocytes in the circulation in UT versus TR during heat stress. Furthermore, UT had a blunted HSP response in their proinflammatory monocyte subset upon subsequent in-vitro heat shock. Combined, these findings imply a cytoprotective adaptation in highly trained individuals, which may help contribute to increased thermotolerance.
Date de publication	2006-06-03
Maison d’édition	American College of Sports Medicine / Wolters Kluwer
Dans	Medicine and Science in Sports and Exercise 38, nº 5 Suppl. : P308–P308.
Langue	anglais
Publications évaluées par des pairs	Oui
Publication du CNRC	Cette publication n’est pas du CNRC Ce sont des publications qui ont été rédigées par un auteur du CNRC, mais avant que celui-ci soit employé du CNRC.
Numéro NPARC	23001451
Exporter la notice	Exporter en format RIS
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Identificateur de l’enregistrement	e5928185-e449-4f96-b89e-42c27cb8d9ae
Enregistrement créé	2017-02-10
Enregistrement modifié	2020-03-03

Date de modification :: 2024-12-30