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- Nilsberth, Camilla, et al.
(författare)
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Peripheral Lipopolysaccharide Administration Induces Cytokine mRNA Expression in the Viscera and Brain of Fever-Refractory Mice Lacking Microsomal Prostaglandin E Synthase-1
- 2009
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Ingår i: Journal of neuroendocrinology (Print). - : Wiley. - 0953-8194 .- 1365-2826. ; 21:8, s. 715-721
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Tidskriftsartikel (refereegranskat)abstract
- We examined the expression of interleukin (IL)-1 beta, IL-6 and tumour necrosis factor (TNF) alpha in mice lacking microsomal prostaglandin E synthase-1 (mPGES-1), which neither produce prostaglandin E-2, nor mount a febrile response upon immune challenge. Intraperitoneal lipopolysaccharide (LPS) injection resulted in a strongly induced expression of all three cytokines in the brain and viscera, similar to wild-type animals. Several brain regions additionally showed modest induction of receptors for these cytokines in both genotypes. Telemetric recordings of body temperature showed that the mPGES-1 deficient mice remained afebrile upon LPS challenge, in contrast to the prominent fever displayed by the wild-type mice. These data demonstrate that LPS-induced cytokine expression occurs independently of prostaglandin E-2, and imply that endogenously expressed IL-1 beta, IL-6, and TNF alpha are not pyrogenic per se, supporting the role of prostaglandin E-2 as the final and obligatory mediator of LPS-induced fever.
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| 2. |
- Nilsberth, Camilla, et al.
(författare)
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The Role of Interleukin-6 in Lipopolysaccharide-Induced Fever by Mechanisms Independent of Prostaglandin E-2
- 2009
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Ingår i: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 150:4, s. 1850-1860
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Tidskriftsartikel (refereegranskat)abstract
- Fever has been shown to be elicited by prostaglandin E-2 (PGE(2)) binding to its receptors on thermoregulatory neurons in the anterior hypothalamus. The signals that trigger PGE(2) production are thought to include proinflammatory cytokines, such as IL-6. However, although the presence of IL-6 is critical for fever, IL- 6 by itself is not or only weakly pyrogenic. Here we examined the relationship between IL-6 and PGE(2) in lipopolysaccharide (LPS)-induced fever. Immune-challenged IL- 6 knockout mice did not produce fever, in contrast to wild-type mice, but the expression of the inducible PGE(2)-synthesizing enzymes, cyclooxygenase-2 and microsomal prostaglandin E synthase-1, was similarly up-regulated in the hypothalamus of both genotypes, which also displayed similarly elevated PGE(2) levels in the cerebrospinal fluid. Nevertheless, both wild-type and knockout mice displayed a febrile response to graded concentrations of PGE(2) injected into the lateral ventricle. There was no major genotype difference in the expression of IL-1 beta and TNF alpha or their receptors, and pretreatment of IL- 6 knockout mice with soluble TNF alpha receptor ip or intracerebroventricularly or a cyclooxygenase-2 inhibitor ip did not abolish the LPS unresponsiveness. Hence, although IL- 6 knockout mice have both an intact PGE(2) synthesis and an intact fever-generating pathway downstream of PGE(2), endogenously produced PGE(2) is not sufficient to produce fever in the absence of IL-6. The findings suggest that IL- 6 controls some factor(s) in the inflammatory cascade, which render(s) IL- 6 knockout mice refractory to the pyrogenic action of PGE(2), or that it is involved in the mechanisms that govern release of synthesized PGE(2) onto its target neurons.
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