Hypothermia enhances phosphorylation of I{kappa}B kinase and prolongs nuclear localization of NF-{kappa}B in lipopolysaccharide-activated macrophages.
Hypothermia (HT) has been associated with both beneficial and detrimental consequences in various pathophysiological states. While HT is generally thought to have anti-inflammatory and cytoprotective effects, we have previously shown that moderate in vitro HT prolongs TNF-alpha production by LPS-stimulated mononuclear phagocytes, in part by prolonging TNF-alpha gene transcription and activation of the pleiotropic transcription factor NF-kappaB. In this study, we have further characterized the effect of moderate (32 degrees C) and marked (28 degrees C) HT in human monocytic THP-1 cells by showing that even short (2 h) exposure to HT followed by a return to normothermic conditions for 22 h resulted in augmented and prolonged production of TNF-alpha. Production of heat shock protein 72 and activation of heat shock factor 1 are not affected by HT in these studies, suggesting that the effect is not part of a generalized stress response. Using immunoblotting, we have shown that HT augments phosphorylation of IKK-beta and IKK-alpha (up to an 8-fold increase at 28 degrees C and a 3.6-fold increase at 32 degrees C vs. 37 degrees C). Furthermore, nuclear accumulation of NF-kappaB p65 was significantly prolonged in hypothermic cells (1.4- and 2.5-fold more nuclear p65 at 2 and 4 h at 28 vs. 37 degrees C). Reexpression of IkappaB-alpha, which contributes to the termination of NF-kappaB-dependent transcription, was delayed several hours in HT-exposed cells. Thus we have shown that clinically relevant HT alters both cytosolic and nuclear events responsible for NF-kappaB activation and deactivation. Enhanced NF-kappaB activation may contribute to the immunomodulatory effects of HT in various clinical settings.
Fairchild
Karen D
KD
Department of Pediatrics, University of Virginia Health System, Box 800386, Charlottesville, VA 22908, USA. kdf2n@virginia.edu
Singh
Ishwar S
IS
Carter
Heather C
HC
Hester
Lisa
L
Hasday
Jeffrey D
JD
D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007036:Hypothermia, Induced; D051550:I-kappa B Kinase; D008070:Lipopolysaccharides / Q000276:immunology; D008262:Macrophage Activation; D008264:Macrophages / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D008070:Lipopolysaccharides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human