Preventing Mycobacterium avium complex in patients who are using protease inhibitors: a cost-effectiveness analysis

Recombinant human interleukin-11 (rhIL-11) is a pleiotropic cytokine with effects on multiple cell types. In addition to thrombopoietic activity, rhIL-11 has demonstrated anti-inflammatory activity in vitro and in vivo. rhIL-11 treatment reduces clinical signs and histologic lesions of colitis in transgenic rats expressing the human major histocompatibility complex (MHC) Class I allele, HLA-B27. We have investigated the effects of rhIL-11 at the molecular and cellular level in this model of inflammatory bowel disease. RT-PCR analysis of colonic RNA revealed that treatment with rhIL-11 down-regulated expression of proinflammatory cytokines including TNF-alpha, IL-1beta, and IFN-gamma. rhIL-11 also reduced the level of myeloperoxidase activity in the cecum indicating reduced inflammation. After stimulation in vitro with anti-CD3 antibody, spleen cell cultures derived from rhIL-11-treated rats produced less IFN-gamma, TNF-alpha, and IL-2 than cultures derived from vehicle-treated rats. These molecular and cellular effects correlated with amelioration of disease as measured by stool character and histologic lesion scores. These findings suggest that rhIL-11 acts to reduce inflammation through modulation of multiple proinflammatory mediators including products of activated T cells. This study has identified pharmacodynamic markers of rhIL-11 anti-inflammatory activity in vivo and supports rhIL-11 therapy to treat inflammatory bowel disease.     

Evidence for the involvement of interleukin 10 in the differential deactivation of murine peritoneal macrophages by prostaglandin E2

Among other effects, prostaglandins (PG) of the E series are known to inhibit several acute and chronic inflammatory conditions in vivo and proinflammatory cytokine production by activated macrophages in culture. The research presented here demonstrates that the inhibitory effect of PGE2 on tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) production by lipopolysaccharide (LPS)-stimulated murine peritoneal macrophages involves IL-10. In a dose-dependent manner, PGE2 inhibits LPS-induced release of TNF-alpha and IL-6, but not of lactate or nitric oxide. The decrease in the level of these cytokines is inversely proportional to the increase in immunoreactive IL-10. This differential inhibitory effect of PGE2 is mimicked by agents that elevate intracellular levels of cAMP, but not cGMP. Neutralizing anti IL-10 antibody but not neutralizing antibodies against other macrophage secretory products (IL-6, leukemia inhibitory factor, and transforming growth factor beta [TGF-beta]), significantly reverse the potent inhibitory effect of PGE2. In vivo, the administration of PGE2 before LPS challenge significantly reduces circulating TNF-alpha and IL-6 levels. Anti-IL-10 antibody substantially enhanced the LPS-induced TNF-alpha and IL-6 levels in mice that received either LPS alone or LPS plus PGE2. These results suggest that the anti-inflammatory effect of PGE2 on mononuclear phagocytes is mediated in part by an autocrine feedback mechanism involving IL-10.     

Lipopolysaccharide-related stimuli induce expression of the secretory leukocyte protease inhibitor, a macrophage-derived lipopolysaccharide inhibitor

Mouse secretory leukocyte protease inhibitor (SLPI) was recently characterized as a lipopolysaccharide (LPS)-induced product of macrophages that antagonizes their LPS-induced activation of NF-kappaB and production of NO and tumor necrosis factor (TNF) (F. Y. Jin, C. Nathan, D. Radzioch, and A. Ding, Cell 88:417-426, 1997). To better understand the role of SLPI in innate immune and inflammatory responses, we examined the kinetics of SLPI expression in response to LPS, LPS-induced cytokines, and LPS-mimetic compounds. SLPI mRNA was detectable in macrophages by Northern blot analysis within 30 min of exposure to LPS but levels peaked only at 24 to 36 h and remained elevated at 72 h. Despite the slowly mounting and prolonged response, early expression of SLPI mRNA was cycloheximide resistant. Two LPS-induced proteins-interleukin-10 (IL-10) and IL-6-also induced SLPI, while TNF and IL-1beta did not. The slow attainment of maximal induction of SLPI by LPS in vitro was mimicked by infection with Pseudomonas aeruginosa in vivo, where SLPI expression in the lung peaked at 3 days. Two LPS-mimetic molecules-taxol from yew bark and lipoteichoic acid (LTA) from gram-positive bacterial cell walls-also induced SLPI. Transfection of macrophages with SLPI inhibited their LTA-induced NO production. An anti-inflammatory role for macrophage-derived SLPI seems likely based on SLPI's slowly mounting production in response to constituents of gram-negative and gram-positive bacteria, its induction both as a direct response to LPS and as a response to anti-inflammatory cytokines induced by LPS, and its ability to suppress the production of proinflammatory products by macrophages stimulated with constituents of both gram-positive and gram-negative bacteria.     

Lipopolysaccharide and its analog antagonists display differential serum factor dependencies for induction of cytokine genes in murine macrophages

Monocytes/macrophages play a central role in mediating the effects of lipopolysaccharide (LPS) derived from gram-negative bacteria by the production of proinflammatory mediators. Recently, it was shown that the expression of cytokine genes for tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interferon-inducible protein-10 (IP-10) by murine macrophages in response to low concentrations of LPS is entirely CD14 dependent. In this report, we show that murine macrophages respond to low concentrations of LPS (相似文献   

Cytokine regulation of human microglial cell IL-8 production

IL-8 involvement in neutrophil activation and chemotaxis may be important in inflammatory responses within the central nervous system, secondary to meningitis, encephalitis, and traumatic injury. The source of IL-8 within the brain during these inflammatory processes, however, is unknown. To explore the role of microglia in the production of IL-8, human fetal microglia, which are the resident macrophages of the brain, were treated with LPS and pro- and anti-inflammatory cytokines to determine their effects on IL-8 production. We found that IL-8 protein levels increased in response to LPS or IL-1 beta, or to TNF-alpha, which also corresponded to elevated IL-8 mRNA levels by RT-PCR. Pretreatment with IL-4, IL-10, or TGF-beta 1 potently inhibited the stimulatory effects of these proinflammatory agents. These findings indicate that human microglia synthesize IL-8 in response to proinflammatory stimuli, and that anti-inflammatory cytokines down-regulate the production of this chemokine. These results may have important therapeutic implications for certain central nervous system insults involving inflammation.     

Macrophage inflammatory protein-1 alpha production in lipopolysaccharide-stimulated human adherent blood mononuclear cells is inhibited by the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine

The release of chemokines such as macrophage-inflammatory protein-1 alpha (MIP-1 alpha) from activated macrophages is a crucial step in cell recruitment necessary for establishing local inflammatory responses. To ascertain the importance of the L-arginine/nitric oxide (NO) pathway in LPS-induced MIP-1 alpha release, we stimulated human adherent PBMC with LPS in the presence of the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA). L-NMMA decreased LPS-induced MIP-1 alpha protein release (45.5% inhibition) and steady state levels of mRNA (48% inhibition) in adherent PBMC. The concentration of L-NMMA for inhibition of MIP-1 alpha release was dependent on the concentration of L-arginine in the cell culture medium, emphasizing the L-arginine-related action of the drug. Most of the MIP-1 alpha release was attributed to the activity of IL-1 and TNF, since coincubation of LPS-stimulated PBMC with IL-1R antagonist and TNF-binding protein abrogated LPS-induced MIP-1 alpha release (by 76.8%). Analysis of cytokine secretion revealed that, in addition to MIP-1 alpha, L-NMMA inhibited the release of mature IL-1 beta (by 70%) and TNF-alpha (by 53%). In contrast, release of macrophage chemoattractant protein-1 was unaffected; IL-10 was augmented (123.4%) by L-NMMA. In the presence of exogenous NO provided by NO donors, LPS-induced MIP-1 alpha release was enhanced. We concluded that endogenous NO acts as a mediator of inflammation. Since IL-10 is a potent anti-inflammatory cytokine, these data also suggest that L-NMMA acts as an anti-inflammatory agent by specifically altering the balance of pro- and anti-inflammatory cytokines released from LPS-stimulated human PBMC.     

Involvement of the IL-2 receptor gamma-chain (gammac) in the control by IL-4 of human monocyte and macrophage proinflammatory mediator production

IL-4 has potent anti-inflammatory properties on monocytes and suppresses both IL-1beta and TNF-alpha production. Well-characterized components of the IL-4 receptor on monocytes include the 140-kDa alpha-chain and the IL-2R gamma-chain, gammac, which normally dimerize 1:1 for signaling from the receptor. However, mRNA levels for gammac were very low in 7-day-cultured monocytes. As mRNA levels for gammac declined with culture, so too did the ability of IL-4 to down-regulate LPS-induced TNF-alpha production. In contrast, IL-4 consistently down-regulated IL-1beta production by cultured monocytes. Immunoprecipitation and Western blot analyses demonstrated that 7-day-cultured monocytes do not express the functionally active 64-kDa gammac protein. This was associated with decreased STAT6 activation by IL-4. Studies with Abs to gammac and an IL-4 mutant that is unable to bind to gammac showed that IL-4 can suppress IL-1beta but not TNF-alpha production by LPS-stimulated monocytes in the presence of little or no functioning gammac. IL-4 also suppressed IL-1beta but not TNF-alpha production by Mono Mac 6 cells, which express minimal levels of gammac. For gammac-expressing LPS/PMA-activated U937 cells, IL-4 decreased both TNF-alpha and IL-1beta production. These results suggest that functional gammac is not present on in vitro-derived macrophages, and that while some anti-inflammatory responses to IL-4 are lost with this down-regulation of functional gammac, others are retained. We conclude that different functional responses to IL-4 by human monocytes and macrophages are regulated by different IL-4 receptor configurations.     

Regulation of monocyte IL-10 synthesis by endogenous IL-1 and TNF-alpha: role of the p38 and p42/44 mitogen-activated protein kinases

IL-10 is an anti-inflammatory cytokine with potent immunomodulatory effects, including inhibition of cytokine production. However, regulation of monocyte IL-10 production is poorly understood. In this report we have investigated the mechanisms of LPS-induced IL-10 production by human peripheral blood monocytes and demonstrate that IL-10 synthesis is uniquely dependent on the endogenous proinflammatory cytokines IL-1 and/or TNF-alpha. LPS signal transduction in monocytes has been shown to involve activation of the p38 and p42 mitogen-activated protein kinase (MAPK) cascades. The results in this paper indicate that inhibition of p38 MAPK potently inhibited the production of IL-10, IL-1beta, and TNF-alpha, whereas blockade of the p42/44 MAPK pathway, while partially inhibiting TNF-alpha and IL-1beta production, had no effect on monocyte secretion of IL-10. Furthermore, neither the inhibition of monocyte TNF-alpha induced by IL-10 nor the stimulation of soluble TNF receptor production was affected by inhibition of the p42/44 MAPK pathway, suggesting that this signaling event is not involved in either monocyte production of or anti-inflammatory responses to IL-10. These data raise the interesting possibility that proinflammatory TNF-alpha-mediated effects may be selectively blocked without modulating the induction or the response to IL-10, whereas the signaling events associated with the anti-inflammatory events induced by IL-10 remain to be elucidated.     

IL-13 protects mice from lipopolysaccharide-induced lethal endotoxemia: correlation with down-modulation of TNF-alpha, IFN-gamma, and IL-12 production

IL-13 is a potent down-modulator of macrophage proinflammatory activity in vitro, similar in this context to the anti-inflammatory cytokines IL-4 and IL-10. Since IL-10 effectively confers protection to mice from LPS-induced lethal endotoxemia through inhibition of proinflammatory cytokine production, we investigated whether IL-13 may also be capable of providing protection in this experimental model of endotoxic shock. A single injection of recombinant murine IL-13 (rmIL-13; 0.5-10 microg) significantly increased survival in a dose-dependent manner when a lethal i.p. injection of endotoxin was administered to BALB/c mice. This effect appeared to be IL-13 specific, since survival was not affected in mice that received heat-inactivated rmIL-13. rmIL-13 provided significant protection to mice even when given 30 min after LPS injection; however, this protection decreased in a time-dependent manner as the administration of rmIL-13 was delayed by 1, 2, and 5 h following LPS injection. The protective effect of IL-13 was correlated with significant decreases in the production of the inflammatory mediators TNF-alpha, IFN-gamma, and IL-12 as well as a decrease in the anti-inflammatory mediator IL-10. Our data suggest that IL-13 provides protection from LPS-induced lethal endotoxemia in a manner that is similar to but independent from that of IL-10, and therefore can be added to the list of cytokine immunomodulators that might be beneficial in the treatment of septic shock.     

In vitro IL-1 beta and TNF-alpha release from THP-1 monocytes in response to metal ions

OBJECTIVES: Previous studies have shown that biomaterials can activate macrophages to produce cytokines and promote an inflammatory response. Although the toxicity of many metal ions has been extensively investigated, little is known about the ability of these ions to alter cytokine release from macrophages. Yet the release of these ions from biomaterials has been well documented. Previous studies indicated that alterations in cytokine release might be expected because metal ions alter protein production in macrophages at sub-toxic concentrations. Thus, the hypothesis of this study was that metal ions can alter the secretion of cytokines from macrophages at sub-toxic concentrations. METHODS: The release of interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) from macrophages was investigated when the macrophages were exposed to metal ions, with or without lipopolysaccharide (LPS), a component of dental plaque. Human THP-1 macrophages were exposed to ions of Ag, Au, Cu, Hg, and Ni for 24 h. In half of the cultures, LPS was added for the last 4 h. The release of IL-1 beta and TNF-alpha into the medium was measured using enzyme-linked immunosorbent assays. ANOVA and Tukey multiple comparison intervals were used to compare the various experimental conditions. RESULTS: None of the metal ions elevated the IL-1 beta or TNF-alpha levels after 24 h, but Ni ions significantly elevated the IL-1 beta and TNF-alpha levels after 72 h. With LPS added, Ag, Cu, and Ni significantly amplified the LPS-induced production of IL-1 beta but only Ni amplified the TNF-alpha response. These alterations in cytokine response occurred with metal ion concentrations which have been previously shown to be released from dental alloys in vitro and in vivo. SIGNIFICANCE: It appeared plausible that macrophage-cytokine mediated inflammatory responses may be altered by the presence of some metal ions in tissues, particularly Ni.     

Inhibition of IL-10 expression by IFN-gamma up-regulates transcription of TNF-alpha in human monocytes

Stimulation of human monocytes with LPS induces expression of multiple cytokines, including TNF-alpha, IL-1 beta, IL-6, and IL-10, IL-10 expression is delayed relative to that of TNF-alpha, IL-1 beta, and IL-6. Furthermore, IL-10 feedback inhibits expression of TNF-alpha, IL-1 beta, and IL-6, thus providing an efficient autocrine mechanism for controlling proinflammatory cytokine production in monocytes. The Th1-type lymphokine, IFN-gamma, markedly up-regulates TNF-alpha production in monocytes. However, the precise mechanism by which IFN-gamma mediates this effect is unknown. We examined the effects of IFN-gamma on IL-10 expression in LPS-stimulated monocytes, and the relationship between IL-10 and TNF-alpha production in these cells. LPS stimulation induced rapid, ordered expression of multiple cytokines. Steady-state mRNA levels for TNF-alpha increased rapidly, reached maximal levels by 2 to 3 h poststimulation, and then declined sharply. IL-1 beta and IL-6 mRNA levels also increased markedly following stimulation with LPS, but decreased more slowly than did TNF-alpha. Down-regulation of mRNA for TNF-alpha, IL-1 beta, and IL-6 coincided with a delayed and more gradual increase in IL-10 mRNA levels. Furthermore, neutralization of IL-10 with anti-IL-10 Abs prolonged TNF-alpha mRNA expression, and significantly increased net TNF-alpha production. IFN-gamma suppressed expression of IL-10 mRNA and protein in a dose-dependent manner. Moreover, inhibition of IL-10 production correlated with a marked increase in both the magnitude and duration of TNF-alpha expression. Thus, potentiation of TNF-alpha production by IFN-gamma in monocytes is coupled to inhibition of endogenous IL-10 expression.     

Localization of mRNA for inflammatory cytokines in radicular cyst tissue by in situ hybridization, and induction of inflammatory cytokines by human gingival fibroblasts in response to radicular cyst contents

The expression of mRNA encoding the inflammatory cytokines interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor alpha(TNF-alpha) have been examined in radicular cysts by in situ hybridization. Furthermore, the biological activity of the contents of radicular cysts (RCC) has been assayed by adding extracts of RCC to cultured human gingival fibroblasts (HGFs) and analyzing the culture medium for the release of inflammatory cytokines. In the epithelial layer, keratinocytes expressed all cytokine mRNAs examined at various levels. Basal layer cells expressed mRNA for each cytokine. In the subepithelial granulation tissue of the cysts, fibroblasts and macrophages expressed mRNA for IL-6, IL-8, IL-1beta and TNF-alpha mRNA at varying levels; especially clear expression of TNF-alpha and IL-1beta mRNA was detected on macrophages. The infiltrating lymphoid cells, largely composed of T cells and plasma cells, expressed these cytokine mRNAs, especially those encoding IL-6 and IL-8, at various levels. In vitro analysis indicated dose-dependent release of both IL-6 and IL-8 by HGFs in response to RCC. After heating to 100 degrees C for 10 min, RCC almost completely failed to stimulate IL-6 release from HGFs. Furthermore, anti-IL-1beta antibody (neutralization test) did not prevent the stimulation of IL-6 release by RCC. Significant amounts of IL-6 and IL-8 were detected in RCC in two cases, and a trace amount of IL-1beta was detected in one case. This study demonstrated the wide expression of mRNA encoding inflammatory cytokines in radicular cyst tissues, and RCC itself was capable of stimulating IL-6 and IL-8 production from HGFs.