Interleukin-10 stabilizes inhibitory kappaB-alpha in human monocytes

• Published in: Shock (Augusta, Ga.) Vol. 10; no. 6; p. 389
• Main Authors: Shames, B D, Selzman, C H, Meldrum, D R, Pulido, E J, Barton, H A, Meng, X, Harken, A H, McIntyre, Jr, R C
• Format: Journal Article
• Language: English
• Published: United States 01.12.1998
• Subjects: Animals; Base Sequence; DNA - genetics; DNA - metabolism; DNA-Binding Proteins - metabolism; Endotoxemia - prevention & control; Humans; I-kappa B Proteins; In Vitro Techniques; Interleukin-10 - pharmacology; Lipopolysaccharides - toxicity; Monocytes - drug effects; Monocytes - metabolism; NF-kappa B - antagonists & inhibitors; NF-kappa B - genetics; NF-KappaB Inhibitor alpha; Tumor Necrosis Factor-alpha - biosynthesis
• ISSN: 1073-2322

Interleukin-10 (IL-10) protects animals from lethal endotoxemia. This beneficial effect is mediated, in part, by inhibition of inflammatory cytokine production, including tumor necrosis factor-alpha (TNF-alpha). Evidence suggests that IL-10 may inhibit activation of the transcription factor nuclear factor-kappaB (NF-kappaB) through an unknown mechanism. NF-kappaB activation in response to inflammatory signals is dependent upon degradation of its associated inhibitory peptide, inhibitory kappaB-alpha (IkappaB-alpha). We hypothesized that IL-10 prevents human monocyte NF-kappaB activation and resultant TNF-alpha production by stabilization of IkappaB-alpha. The purpose of this study was to determine the effect of IL-10 on lipopolysaccharide (LPS)-induced human monocyte TNF-alpha production, NF-kappaB activation, and IkappaB-alpha degradation. Monocytes were isolated from human donors. Cells were stimulated with endotoxin (LPS, 100 ng/mL) with and without human IL-10 (10 ng/mL). Following stimulation, TNF-alpha was measured in cell supernatants by ELISA, NF-kappaB activity by electrophoretic mobility shift assay, and IkappaB-alpha levels by Western blot. We observed that after LPS stimulation of human monocytes, TNF-alpha increased to 798+/-67 pg/mL (p < .001 versus control). IL-10 attenuated LPS-stimulated TNF-alpha production (297+/-54; p < .001 versus LPS alone). After LPS stimulation in human monocytes, IkappaB-alpha protein levels decreased, and NF-kappaB DNA binding increased. IL-10 pretreatment prevented LPS-induced decreases in IkappaB-alpha protein levels and attenuated NF-kappaB DNA binding. IL-10 appears to prevent activation of NF-kappaB by preserving IkappaB-alpha protein levels, leading to a reduction in TNF-alpha release.