title: Naturally occurring hypothermia is more advantageous than fever in severe forms of lipopolysaccharide- and Escherichia coli-induced systemic inflammation.
abstract: The natural switch from fever to hypothermia observed in the most severe cases of systemic inflammation is a phenomenon that continues to puzzle clinicians and scientists. The present study was the first to evaluate in direct experiments how the development of hypothermia vs. fever during severe forms of systemic inflammation impacts the pathophysiology of this malady and mortality rates in rats. Following administration of bacterial lipopolysaccharide (LPS; 5 or 18 mg/kg) or of a clinical Escherichia coli isolate (5 × 10(9) or 1 × 10(10) CFU/kg), hypothermia developed in rats exposed to a mildly cool environment, but not in rats exposed to a warm environment; only fever was revealed in the warm environment. Development of hypothermia instead of fever suppressed endotoxemia in E. coli-infected rats, but not in LPS-injected rats. The infiltration of the lungs by neutrophils was similarly suppressed in E. coli-infected rats of the hypothermic group. These potentially beneficial effects came with costs, as hypothermia increased bacterial burden in the liver. Furthermore, the hypotensive responses to LPS or E. coli were exaggerated in rats of the hypothermic group. This exaggeration, however, occurred independently of changes in inflammatory cytokines and prostaglandins. Despite possible costs, development of hypothermia lessened abdominal organ dysfunction and reduced overall mortality rates in both the E. coli and LPS models. By demonstrating that naturally occurring hypothermia is more advantageous than fever in severe forms of aseptic (LPS-induced) or septic (E. coli-induced) systemic inflammation, this study provides new grounds for the management of this deadly condition.
authors.affiliation: Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York 12208, USA.
authors.forename: Elaine
authors.initials: E
authors.lastname: Liu
authors.forename: Kevin
authors.initials: K
authors.lastname: Lewis
authors.forename: Hiba
authors.initials: H
authors.lastname: Al-Saffar
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Krall
authors.forename: Anju
authors.initials: A
authors.lastname: Singh
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Kulchitsky
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Corrigan
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Simons
authors.forename: Scott R
authors.initials: SR
authors.lastname: Petersen
authors.forename: Florin M
authors.initials: FM
authors.lastname: Musteata
authors.forename: Chandra S
authors.initials: CS
authors.lastname: Bakshi
authors.forename: Andrej A
authors.initials: AA
authors.lastname: Romanovsky
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Sellati
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: Steiner
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D004926:Escherichia coli; D005334:Fever / Q000139:chemically induced / Q000503:physiopathology*; D007035:Hypothermia / Q000139:chemically induced / Q000503:physiopathology*; D007249:Inflammation / Q000139:chemically induced / Q000503:physiopathology*; D008070:Lipopolysaccharides; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: D008070:Lipopolysaccharides