Regulatory effects of fever-range whole-body hyperthermia on the LPS-induced acute inflammatory response

The thermal component of fever is one of the most poorly understood aspects of inflammation. To evaluate the role of fever-range hyperthermia on acute inflammation, BALB/c and C57BL/6 mice were exposed to mild, long-duration whole-body hyperthermia (WBH), and serum concentrations of tumor necrosis f actor alpha (TNF-alpha), interleukin-6 (IL-6), IL-1 beta, and the acute pha se proteins (APPs) al-acid glycoprotein and haptoglobin were analyzed. WBH alone did not affect serum concentrations of these cytokines or APPs when c ompared with controls, In contrast, when WBH was applied just after intrape ritoneal administration of lipopolysaccharide (LPS), serum concentrations o f TNF-alpha and IL-6 were greater than or equal to threefold higher in BALB /c mice compared with LPS-treated controls. LPS-induced IL-6 levels were al so enhanced in WBH-treated C57BL/6 mice. However, APP levels were prolonged only in WBH-treated BALB/c mice, It is interesting that in vitro hyperther mia treatment of LPS-stimulated peritoneal cells resulted in decreased cyto kine production compared with controls. These results suggest that fever-ra nge hyperthermia regulates acute inflammation in a mouse strain-specific ma nner that is more complex than that observed in vitro.