Open AccessNuclear Factor (NF)-KB Activation in Human Peripheral Blood Mononuclear Cells Of Trained Versus Untrained Individuals During Exertional Heat Stress
Author(s) -
Glen A. Selkirk,
Heather E. Wright,
Tom M. McLellan,
Shawn G. Rhind
Publication year - 2007
Publication title -
medicine and science in sports and exercise
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.703
H-Index - 224
eISSN - 1530-0315
pISSN - 0195-9131
DOI - 10.1249/01.mss.0000273139.54027.b5
Subject(s) - peripheral blood mononuclear cell , p50 , transcription factor , rectal temperature , stimulation , medicine , chemistry , endocrinology , andrology , immunology , in vitro , biochemistry , gene
Inflammatory responses are regulated by transcription factor NF-KB, predominately inactive in the cytoplasm. Upon activation, NF-KB translocation into the nucleus regulates gene transcription of pro inflammatory cytokines.PURPOSE: The purpose of this study was to examine the effect of a single bout of exertional heat stress (EHS) on NF-?B DNA-binding in human peripheral blood mononuclear cells (PBMC) of trained (TR) and untrained (UT) individuals.METHODS: Maximum oxygen consumption expressed per kg of lean body mass (LBM) and activity history was used to divide subjects into TR (n=12, VO2peak= 70 \ub1 2 mL-kgLBM-l-mm-1) and UT (n=10, VO2peak= 50 \ub1 1 mL-kgLBM-l-mm-1) groups. Subjects walked at 4.5 km-h-1 with 2% elevation in a climatic chamber (40\ub0C; 30% R.H.) wearing military biological and chemical protective clothing until specific end-point criteria were attained. Venous blood samples were collected at baseline (B), rectal temperatures of 38.0\ub0C, 38.5\ub0C, 39.0\ub0C and at exhaustion (Exh). Whole blood was analysed by flow cytometry for intranuclear inflammatory transcription factor NF-KB in PBMC. Similar analyses were performed following in vitro lipopolysacharide (LPS) stimulation (30 min,100ng/mL).RESULTS: Rectal temperature (Tre) tolerated at Exh was higher in TR (39.7 \ub1 0.1 \ub0C) compared to UT (39.1 \ub1 0.1\ub0C), however, the rate of Tre increase was not significantly different between the groups (1.0 \ub1 0.05 \ub0C/hr). Exertional heat stress induced a temperature dependent elevation in the absolute count (x109cell/L) of PBMC expressing NF-KB in TR and UT compared to B. Intranuclear NF-KB relative mean fluorescence intensity (MFI) was elevated compared to B in both TR and UT at 38.5\ub0C and in TR at 39.5\ub0C. At Exh, intranuclear NF-KB DNA-binding was not significantly different from B in vivo. Additional in vitro LPS stimulation induced a significantly greater increase in NF-KB DNA-binding from B compared to Exh.CONCLUSIONS: These findings suggest that the observed upregulation of intranuclear NF-KB in circulating PBMC during EHS may be attributed to both leukocyte mobilization and/or NF-KB translocation. Although there were no significant differences observed between TR and UT up to 39.0\ub0C, EHS was found to increase LPS tolerance upon stimulation in vitro.Peer reviewed: YesNRC publication: N