Selected Contribution: Synergism between TNF-α and IL-1β in airway smooth muscle cells: implications for β-adrenergic responsiveness

Abstract

In human cultured airway smooth muscle cells, interleukin (IL)-1 beta increases cyclooxygenase (COX)-2 expression and PGE(2) release, ultimately resulting in decreased beta-adrenergic responsiveness. In this study, we aimed to determine whether tumor necrosis factor-alpha (TNF-alpha) synergizes with IL-1 beta in the induction of these events. TNF-alpha alone, at concentrations up to 10 ng/ml, had no effect on COX-2 protein expression; at concentrations as low as 0.1 ng/ml, it significantly enhanced the ability of IL-1 beta (0.2 ng/ml) to induce COX-2 and to increase PGE(2) release. IL-1 beta and TNF-alpha in combination also significantly enhanced COX-2 promoter activity, indicating that synergism between the cytokines is mediated at the level of gene transcription. Although IL-1 beta and TNF-alpha each increased nuclear factor-kappa B activation and induced extracellular regulated kinase and p38 phosphorylation, combined administration of the cytokines did not enhance either nuclear factor-kappa B or mitogen-activated protein kinase activation. Combined administration of IL-1 beta (0.2 ng/ml) and TNF-alpha (0.1 or 1.0 ng/ml) reduced the ability of isoproterenol to decrease human airway smooth muscle cell stiffness, as measured by magnetic twisting cytometry, even though individually these cytokines, at these concentrations, had no effect on isoproterenol responses. Treatment with the selective COX-2 inhibitor NS-398 abolished the synergistic effects of TNF-alpha and IL-1 beta on beta-adrenergic responsiveness. Our results indicate that low concentrations of IL-1 beta and TNF-alpha synergize to promote beta-adrenergic hyporesponsiveness and that effects on COX-2 expression and PGE(2) are responsible for these events. The data suggest that the simultaneous release in the airway, of even very small amounts of cytokines, can have important functional consequences.

p38 MAPK and NF-κB mediate COX-2 expression in human airway myocytes

“…This work concurs with other reports examining p38 MAPK-mediated regulation of COX-2 expression in airway smooth muscle cells stimulated with IL-1␤ and TNF-␣ (16,22,42). The experiments presented here more clearly delineate that p38 MAPK, and not ERK MAPK, contributes to cytokine-stimulated COX-2 expression in response to a more complex inflammatory stimulus.…”

“…The data presented here further describe expression of COX-2 in cultured BSMC exposed to a complex proinflammatory stimulus of IL-1␤, TNF-␣, and IFN-␥, which has been previously shown to induce COX-2 expression in cells isolated from human tracheal smooth muscle (3). Although several reports in the literature have examined COX-2 expression in response to IL-1␤ or a combination of IL-1␤ and TNF-␣ in airway smooth muscle (22,26,42), our data suggest that the addition of IFN-␥ to the cytokine stimulus synergistically stimulates PGE 2 synthesis from endogenous arachidonic acid and also contributes to increases in COX-2 expression. Therefore, the use of a stimulus that includes IFN-␥ may yield important information about the regulation of inflammatory mediators.…”

Expression of Prostaglandin E Synthases in Periodontitis

“…The expression of PGE synthases has not been previously reported in HASM cells, although COX-2 expression and PGE 2 production have been shown to be increased by IL-1␤, which is in accord with our results. 60 Similar to the present results, the expression of PGE synthases and the up-regulation of mPGES-1, COX-2, and PGE 2 in response to IL-1␤ and TNF-␣ have also been demonstrated in primary human vascular smooth muscle cells. 61,62 In one of those studies, 62 the authors also demonstrated the lack of mPGES-1 induction in HUVEC cells, which is in accord with our results obtained from HUVEC cells.…”

Effect of IL-1β on CRE-dependent gene expression in human airway smooth muscle cells

“…We previously reported that TNF-␣ has only minimal effects on the ability of ISO to relax HASM cells (18). To confirm that TNF-␣ also does not alter ISO-induced changes in cAMP formation, as has previously been reported (22) (Fig.…”

“…In contrast to IL-1␤, TNF-␣ did not alter basal CRE-driven gene expression in HASM cells (Fig. 8), likely because TNF-␣ does not induce COX-2 expression in HASM cells (18). However, similar to IL-1␤, TNF-␣ did attenuate the ability of ISO to induce luciferase expression (Fig.…”