Interleukin 1 and interleukin 18 as mediators of inflammation and the aging process.
In this review, 2 cytokines are discussed with respect to the inflammatory processes that are fundamental to aging and mortality. Both interleukin (IL)-1 and IL-18 are members of the same structural family (IL-1 family, or IL-F); there are presently 9 members of this family, but with the exception of IL-1alpha, IL-1beta, and IL-18, the others are antagonists or remain without known function. IL-1alpha is an intracellular cytokine with properties of both a cytokine and a transcription factor. IL-1beta and IL-18 are closely related; both possess a similar three-dimensional structure, and their respective precursor forms are inactive until cleaved by the intracellular cysteine protease caspase-1. Patients with mutations in the NALP3 gene, which controls the activity of caspase-1, readily secrete more IL-1beta and IL-18 and suffer from systemic inflammatory diseases. Patients with defects in this gene have high circulating concentrations of IL-6, serum amyloid A, and C-reactive protein, each of which decrease rapidly upon blockade of the IL-1 receptor, which suggests that IL-1beta contributes to the elevation of these markers of the inflammatory mechanisms of aging. Animal studies support the concept that IL-1beta and IL-18 participate in the pathogenesis of atherosclerosis. For example, overexpression of the IL-18 binding protein, a naturally occurring, specific inhibitor of IL-18, prevents the spontaneous development of atherosclerosis in apolipoprotein E-deficient mice. From human and animal studies, one may conclude that IL-1beta and IL-18 participate in fundamental inflammatory processes that increase during the aging process.
Department of Medicine, Division of Infectious Diseases, University of Colorado Health Sciences Center, Denver, CO 80262, USA. cdinare333@aol.com
Charles A
CA
Dinarello
D000368:Aged; D000375:Aging / Q000276:immunology* / Q000502:physiology; D020170:Caspase 1 / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007249:Inflammation / Q000503:physiopathology*; D018836:Inflammation Mediators / Q000378:metabolism / Q000502:physiology*; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D020382:Interleukin-18 / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction
D018836:Inflammation Mediators; D007375:Interleukin-1; D020382:Interleukin-18; D020170:Caspase 1