Regulation of lipopolysaccharide-mediated interleukin-1beta release by N-acetylcysteine in THP-1 cells

Hydroxy-Selenomethionine, an Organic Selenium Source, Increases Selenoprotein Expression and Positively Modulates the Inflammatory Response of LPS-Stimulated Macrophages

The role of 2-hydroxy-(4-methylseleno)butanoic acid (OH-SeMet), a form of organic selenium (Se), in selenoprotein synthesis and inflammatory response of THP1-derived macrophages stimulated with lipopolysaccharide (LPS) has been investigated. Glutathione peroxidase (GPX) activity, GPX1 gene expression, selenoprotein P (SELENOP) protein and gene expression, and reactive oxygen species (ROS) production were studied in Se-deprived conditions (6 and 24 h). Then, macrophages were supplemented with OH-SeMet for 72 h and GPX1 and SELENOP gene expression were determined. The protective effect of OH-SeMet against oxidative stress was studied in H₂O₂-stimulated macrophages, as well as the effect on GPX1 gene expression, oxidative stress, cytokine production (TNFα, IL-1β and IL-10), and phagocytic and killing capacities after LPS stimulation. Se deprivation induced a reduction in GPX activity, GPX1 gene expression, and SELENOP protein and gene expression at 24 h. OH-SeMet upregulated GPX1 and SELENOP gene expression and decreased ROS production after H₂O₂ treatment. In LPS-stimulated macrophages, OH-SeMet upregulated GPX1 gene expression, enhanced phagocytic and killing capacities, and reduced ROS and cytokine production. Therefore, OH-SeMet supplementation supports selenoprotein expression and controls oxidative burst and cytokine production while enhancing phagocytic and killing capacities, modulating the inflammatory response, and avoiding the potentially toxic insult produced by highly activated macrophages.

Therapeutic Potential of Small Molecules Targeting Oxidative Stress in the Treatment of Chronic Obstructive Pulmonary Disease (COPD): A Comprehensive Review

Chronic obstructive pulmonary disease (COPD) is an increasing and major global health problem. COPD is also the third leading cause of death worldwide. Oxidative stress (OS) takes place when various reactive species and free radicals swamp the availability of antioxidants. Reactive nitrogen species, reactive oxygen species (ROS), and their counterpart antioxidants are important for host defense and physiological signaling pathways, and the development and progression of inflammation. During the disturbance of their normal steady states, imbalances between antioxidants and oxidants might induce pathological mechanisms that can further result in many non-respiratory and respiratory diseases including COPD. ROS might be either endogenously produced in response to various infectious pathogens including fungi, viruses, or bacteria, or exogenously generated from several inhaled particulate or gaseous agents including some occupational dust, cigarette smoke (CS), and air pollutants. Therefore, targeting systemic and local OS with therapeutic agents such as small molecules that can increase endogenous antioxidants or regulate the redox/antioxidants system can be an effective approach in treating COPD. Various thiol-based antioxidants including fudosteine, erdosteine, carbocysteine, and N-acetyl-L-cysteine have the capacity to increase thiol content in the lungs. Many synthetic molecules including inhibitors/blockers of protein carbonylation and lipid peroxidation, catalytic antioxidants including superoxide dismutase mimetics, and spin trapping agents can effectively modulate CS-induced OS and its resulting cellular alterations. Several clinical and pre-clinical studies have demonstrated that these antioxidants have the capacity to decrease OS and affect the expressions of several pro-inflammatory genes and genes that are involved with redox and glutathione biosynthesis. In this article, we have summarized the role of OS in COPD pathogenesis. Furthermore, we have particularly focused on the therapeutic potential of numerous chemicals, particularly antioxidants in the treatment of COPD.

Paeonol reduces IL-β production by inhibiting the activation of nucleotide oligomerization domain-like receptor protein-3 inflammasome and nuclear factor-κB in macrophages

Interleukin-1β, a key cytokine in gouty inflammation, is precisely regulated by the NLRP3 inflammasome and NF-κB. Our previous study demonstrated that paeonol suppressed IL-1β production in rats with monosodium urate (MSU)-induced arthritis. Whether NLRP3 inflammasome or NF-κB is responsible for the anti-inflammatory effect of paeonol remains unclear. In this study, J774A.1 cells induced by lipopolysaccharide (LPS) plus MSU, was used to investigate the effect of paeonol on NLRP3 inflammasome activation, and J774A.1 cells induced by LPS alone were used to investigate the effect of paeonol on NF-κB activation. In J774A.1 cells induced by LPS plus MSU, paeonol decreased the levels of IL-1β and caspase-1 and reduced the MSU-induced interaction of pro-caspase-1 and apoptosis-associated speck-like protein containing caspase recruitment domain (ASC), but did not affect the levels of pro-IL-1β and pro-caspase-1. In J774A.1 cells induced by LPS alone, paeonol reduced the levels of IL-1β, NLRP3, p-IKK, p-IκBα, and p-p65, but did not affect ASC levels. Paeonol also promoted the content of IκBα and retained more p65 in the cytoplasm. Furthermore, paeonol reduced the DNA-binding activity of p65 and lowered the levels of p-JNK, p-ERK, and p-p38. These results suggest that paeonol inhibits IL-1β production by inhibiting the activation of NLRP3 inflammasome, NF-κB, and MAPK signaling pathways.

Redox regulation of immunity and the role of small molecular weight thiols

It is thought that excessive production of reactive oxygen species (ROS) can be a causal component in many diseases, some of which have an inflammatory component. This led to an oversimplification whereby ROS are seen as inflammatory and antioxidants anti-inflammatory. This paper aims at reviewing some of the literature on thiols in host defense. The review will first summarize the mechanisms by which we survive infections by pathogens. Then we will consider how the redox field evolved from the concept of oxidative stress to that of redox regulation and how it intersects the field of innate immunity. A third section will analyze how an oversimplified oxidative stress theory of disease led to a hypothesis on the role of ROS and glutathione (GSH) in immunity, respectively as pro- and anti-inflammatory mediators. Finally, we will discuss some recent research and how to think out of the box of that oversimplification and link the role of thiols in redox regulation to the mechanisms by which we survive an infection outlined in the first section.

Simultaneous targeting of oxidative stress and fibrosis reverses cardiomyopathy-induced ventricular remodelling and dysfunction

BACKGROUND AND PURPOSE

Oxidative stress and fibrosis are hallmarks of cardiomyopathy-induced heart failure yet are not effectively targeted by current frontline therapies. Here, the therapeutic effects of the anti-oxidant, N-acetylcysteine (NAC), were compared and combined with an acute heart failure drug with established anti-fibrotic effects, serelaxin (RLX), in a murine model of cardiomyopathy.

EXPERIMENTAL APPROACH

Adult male 129sv mice were subjected to repeated isoprenaline (25 mg·kg^-1 )-induced cardiac injury for five consecutive days and then left to undergo fibrotic healing until Day 14. Subgroups of isoprenaline-injured mice were treated with RLX (0.5 mg·kg^-1 ·day^-1 ), NAC (25 mg·kg^-1 ·day^-1 ) or both combined, given subcutaneously via osmotic minipumps from Day 7 to 14. Control mice received saline instead of isoprenaline.

KEY RESULTS

Isoprenaline-injured mice showed increased left ventricular (LV) inflammation (~5-fold), oxidative stress (~1-2.5-fold), cardiomyocyte hypertrophy (~25%), cardiac remodelling, fibrosis (~2-2.5-fold) and dysfunction by Day 14 after injury. NAC alone blocked the cardiomyopathy-induced increase in LV superoxide levels, to a greater extent than RLX. Additionally, either treatment alone only partly reduced several measures of LV inflammation, remodelling and fibrosis. In comparison, the combination of RLX and NAC prevented the cardiomyopathy-induced LV macrophage infiltration, remodelling, fibrosis and cardiomyocyte size, to a greater extent than either treatment alone after 7 days. The combination therapy also restored the isoprenaline-induced reduction in LV function, without affecting systolic BP.

CONCLUSION AND IMPLICATIONS

These findings demonstrated that the simultaneous targeting of oxidative stress and fibrosis is key to treating the pathophysiology and dysfunction induced by cardiomyopathy.

Glutathione "Redox Homeostasis" and Its Relation to Cardiovascular Disease

More people die from cardiovascular diseases (CVD) than from any other cause. Cardiovascular complications are thought to arise from enhanced levels of free radicals causing impaired "redox homeostasis," which represents the interplay between oxidative stress (OS) and reductive stress (RS). In this review, we compile several experimental research findings that show sustained shifts towards OS will alter the homeostatic redox mechanism to cause cardiovascular complications, as well as findings that show a prolonged antioxidant state or RS can similarly lead to such cardiovascular complications. This experimental evidence is specifically focused on the role of glutathione, the most abundant antioxidant in the heart, in a redox homeostatic mechanism that has been shifted towards OS or RS. This may lead to impairment of cellular signaling mechanisms and elevated pools of proteotoxicity associated with cardiac dysfunction.

GSH-C4 Acts as Anti-inflammatory Drug in Different Models of Canonical and Cell Autonomous Inflammation Through NFκB Inhibition

An imbalance in GSH/GSSG ratio represents a triggering event in pro-inflammatory cytokine production and inflammatory response. However, the molecular mechanism(s) through which GSH regulates macrophage and cell autonomous inflammation remains not deeply understood. Here, we investigated the effects of a derivative of GSH, the N-butanoyl glutathione (GSH-C4), a cell permeable compound, on lipopolisaccharide (LPS)-stimulated murine RAW 264.7 macrophages, and human macrophages. LPS alone induces a significant production of pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α and a significant decrement of GSH content. Such events were significantly abrogated by treatment with GSH-C4. Moreover, GSH-C4 was highly efficient in buffering cell autonomous inflammatory status of aged C2C12 myotubes and 3T3-L1 adipocytes by suppressing the production of pro-inflammatory cytokines. We found that inflammation was paralleled by a strong induction of the phosphorylated form of NFκB, which translocates into the nucleus; a process that was also efficiently inhibited by the treatment with GSH-C4. Overall, the evidence suggests that GSH decrement is required for efficient activation of an inflammatory condition and, at the same time, GSH-C4 can be envisaged as a good candidate to abrogate such process, expanding the anti-inflammatory role of this molecule in chronic inflammatory states.

The dental monomer hydroxyethyl methacrylate (HEMA) counteracts lipopolysaccharide-induced IL-1β release-Possible role of glutathione

Methacrylate monomers, like 2-hydroxyethyl methacrylate (HEMA), are common components of resin based dental materials. Leakage of unpolymerized monomers after placement and curing leads to human exposure. HEMA is known to inhibit lipopolysaccharide (LPS) induced cytokine release. In this study we explore a possible role of the antioxidant glutathione (GSH) in this effect. In the RAW 264.7 murine macrophage cell line, HEMA (<2mM) did not induce cell death, but reduced cellular GSH levels, increased cellular ROS and decreased the IL-1β release from LPS-stimulated cells. Moreover, the IL-1β mRNA levels were reduced after 3-6h exposure, suggesting transcriptional effects of HEMA. The GSH modulators butylsulfoximine (BSO; inhibitor of GSH synthesis) and 2-oxothiazolidine-4-carboxylate (OTC; Cysteine precursor) caused a decrease and increase in the LPS-induced IL-1β release, respectively, suggesting a role for GSH in negative regulation of LPS-induced IL-1β release. However, the magnitude and dynamics of the effects of HEMA and BSO on LPS-induced IL-1β release and GSH depletion differed considerably. Thus, GSH depletion alone could not explain the strong attenuation of LPS-induced IL-1β release caused by HEMA. Formation of HEMA-protein conjugates due to the thiol reactivity of HEMA emerges as a likely candidate for the molecular mechanism accounting for this effect.

Antitumoral effect of a selective Rho-kinase inhibitor Y-27632 against Ehrlich ascites carcinoma in mice

BACKGROUND

The Rho proteins and Rho-kinase (ROCK) enzymes are responsible for signal transduction, and cause cell permeability, contractility, differentiation, migration, proliferation or apoptosis depending on cell types. All of these functions are vital for cancer initiation and progression. In this study, the preventive and protective effects of a selective ROCK inhibitor Y-27632 against Ehrlich ascites carcinoma in Swiss albino mice were investigated.

METHODS

Adult male albino mice were divided into five equal groups, and Y-27632 (0.1, 1, and 10 mg/kg) was given to groups as two steps; before (pre-carcinoma) and after inoculation of carcinoma cell suspensions (post-carcinoma). At the end of the experiments (at day 15), cardiac blood samples, the ascitic fluid, and intestinal specimens were collected for histopathology and biochemical investigation.

RESULTS

Significant decreases in the body weight and immunostaining scores in small and large intestine for ROCK2, preservation of serum glutathione (GSH) levels, and an increase in tumor level of nitric oxide were recorded in groups pretreated with Y-27632. However, treatment with Y-27632 after tumor inoculation did not affect body weight and ROCK2 immunostaining scores, increased serum MDA levels, and decreased GSH levels.

CONCLUSIONS

This is the first study on the effectiveness of Y-27632 in this experimental tumor model. Our findings provided direct evidence for ROCK involvement in tumor development. These data suggest that pretreatment with Y-27632 has a protective effect against tumor formation.

RETRACTED: NAD(P)H:quinone oxidoreductase 1 protects lungs from oxidant-induced emphysema in mice

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Authors. Since learning of potential discrepancies between the raw data from the animal pulmonary physiology laboratory at Duke that were used to calculate the in vivo pulmonary mechanics and the re-exported machine-generated raw data, some studies published elsewhere have been replicated successfully. However it is not possible to replicate this study as the NQO1-deficient mice on the C57BL/6 background are no longer available from the NCI. The authors recognize that previous work to identify differences in alveolar size can vary dependent on background strain when comparing inbred mouse strains (Soutiere SE et al Resp Physiol Neurobiol 2004;140(3)183–91 doi: 10.1016/j.resp.2004.02.003). Because of the prolonged period of time required to successfully backcross NQO1-deficient animals onto C57BL/6J background and the time required to repeat studies presented in this manuscript the authors think it does not seem feasible to conduct replicate studies in a reasonable timeline. Therefore, the most appropriate course of action is to retract the report as it is the authors' goal to maintain accuracy of the scientific record to the best of their ability. The authors offer sincere apologies to the scientific community.

Gain and loss of function for glutathione synthesis: impact on advanced atherosclerosis in apolipoprotein E-deficient mice

OBJECTIVE

Glutamate-cysteine ligase (GCL) is the rate-limiting step in glutathione synthesis. The enzyme is a heterodimer composed of a catalytic subunit, GCLC, and a modifier subunit, GCLM. We generated apolipoprotein E (apoE)-/- mice deficient in GCLM (apoE-/-/Gclm-/-) and transgenic mice that overexpress GCLC specifically in macrophages (apoE-/-/Gclc-Tg) to test the hypothesis that significantly altering the availability of glutathione has a measurable impact on both the initiation and progression of atherosclerosis.

METHODS AND RESULTS

Atherosclerotic plaque size and composition were measured in the innominate artery in chow-fed male and female mice at 20, 30, 40, and 50 weeks of age and in the aortic sinus at 40 and 50 weeks of age. The apoE-/-/Gclm-/- mice more rapidly developed complex lesions, whereas the apoE-/-/Gclc-Tg mice had reduced lesion development compared with the littermate apoE-/- control mice. Transplantation of bone marrow from the apoE-/-/Gclm-/- and apoE-/-/Gclc-Tg mice into apoE-/- mice with established lesions also stimulated or inhibited further lesion development at 30 weeks posttransplant.

CONCLUSION

Gain and loss of function in the capacity to synthesize glutathione especially in macrophages has reciprocal effects on the initiation and progression of atherosclerosis at multiple sites in apoE-/- mice.

Di-(2-ethylhexyl) phthalate induces production of inflammatory molecules in human macrophages

OBJECTIVE AND DESIGN

To investigate whether di-(2-ethylhexyl) phthalate (DEHP) affects the production of inflammatory cytokines by human macrophages.

MATERIALS AND METHODS

Differentiated macrophage-like THP-1 cells were exposed to 200 μM DEHP for 3 h, followed by incubation in the presence or absence of opsonized zymosan A, and the concentrations of TNF-α, IL-1β, IL-8, and IL-6 in the culture media were determined by ELISA. DNA microarray and quantitative real-time RT-PCR analyses were performed to identify genes that showed changes in expression in response to DEHP.

RESULTS

DEHP treatment increased the concentrations of TNF-α, IL-1β, IL-8, and IL-6 in the media, regardless of whether the cells phagocytosed zymosan. DNA microarray analysis showed that DEHP increased the levels of expression of IL-8, CXCL1, CXCL2, CXCL3, CXCL6, CCL3, MMP3, MMP10, MMP14, and CSF2 mRNA, and real-time RT-PCR showed that DEHP significantly enhanced the levels of expression of IL-8, CXCL1, CXCL2, CXCL3, CXCL6, CCL3, MMP10, CSF2, TNF-α, IL-1β, and IL-6 mRNA in THP-1 cells. DEHP significantly induced translocation of p65 NF-κB into the nucleus.

CONCLUSION

DEHP enhances the production of inflammatory cytokines and chemokines by macrophages, and exacerbates their inflammatory response.

The suppressive effects of lanthanum on the production of inflammatory mediators in mice challenged by LPS

Lanthanide ions have been proven to have various biologic effects. Lanthanum with extremely active physical and chemical property was evidenced to possess antibacterial and immune adjustment effects. In the present study, the anti-inflammatory effects of lanthanum chloride (LaCl(3)) on lipopolysaccharide (LPS)-challenged mice were examined in vivo and in vitro. The results indicated that LaCl(3) can greatly decrease the secretion of tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1β as well as TNF-α mRNA expression in the mice challenged with LPS. To clarify the mechanism involved, the effects of LaCl(3) on the activation of nuclear factor (NF)-κB were examined both in liver and in peritoneal macrophages. The LPS-induced activation of NF-κB was significantly blocked by LaCl(3). These findings demonstrate that the inhibition of the LPS-induced inflammatory media, such as TNF-α and IL-1β, by LaCl(3), is due to the inhibition of NF-κ B activation.

Glutathione in cancer cell death

Glutathione (L-γ-glutamyl-L-cysteinyl-glycine; GSH) in cancer cells is particularly relevant in the regulation of carcinogenic mechanisms; sensitivity against cytotoxic drugs, ionizing radiations, and some cytokines; DNA synthesis; and cell proliferation and death. The intracellular thiol redox state (controlled by GSH) is one of the endogenous effectors involved in regulating the mitochondrial permeability transition pore complex and, in consequence, thiol oxidation can be a causal factor in the mitochondrion-based mechanism that leads to cell death. Nevertheless GSH depletion is a common feature not only of apoptosis but also of other types of cell death. Indeed rates of GSH synthesis and fluxes regulate its levels in cellular compartments, and potentially influence switches among different mechanisms of death. How changes in gene expression, post-translational modifications of proteins, and signaling cascades are implicated will be discussed. Furthermore, this review will finally analyze whether GSH depletion may facilitate cancer cell death under in vivo conditions, and how this can be applied to cancer therapy.

N-acetylcysteine attenuates phosgene-induced acute lung injury via up-regulation of Nrf2 expression

Previous studies indicated that oxidative stress was involved in phosgene-induced acute lung injury (ALI) and many antioxidants had been used to prevent ALI. N-acetylcysteine (NAC) had been used to protect ALI induced by various types of oxidative stress. Considering the limited information of NAC on phosgene-induced ALI, the purpose of this study was to elucidate the molecular mechanisms of phosgene-induced ALI and the protective effects of NAC. This study discovered that intraperitoneal administration of NAC significantly alleviated phosgene-induced pulmonary edema, as confirmed by decreased lung wet to dry weight ratio and oxidative stress markers. The content of l-gamma-glutamyl-l-cysteinyl-glycine (glutathione; GSH) and the ratio of the reduced and disulfide forms (GSH/GSSG), significant indicators of the antioxidative ability, were apparently inhibited by phosgene exposure. However, both indicators could be reversed by NAC administration, indicating that dysregulation of redox status of glutathione might be the cause of phosgene-induced ALI. The nuclear factor (NF)-E2-related factor 2 (Nrf2), which has been proven to up-regulate the expression of glutathione reductase (GR), was obviously decreased by phosgene exposure. However, NAC administration elevated Nrf2 expression significantly. In conclusion, these data provided the first evidences showing that it was the transcriptional factor Nrf2 that connected phosgene-induced ALI with GSH metabolism. NAC protected against oxidative stress through acting on this newly disclosed Nrf2/GR/GSH pathway, by which NAC elevated the biosynthesis of protective GSH to repair and reconstitute the defense system destroyed by phosgene.

In Vitro Effects of the Reduced Form of Coenzyme Q(10) on Secretion Levels of TNF-alpha and Chemokines in Response to LPS in the Human Monocytic Cell Line THP-1

Ubiquinol-10 (QH₂), the reduced form of Coenzyme Q₁₀ (CoQ₁₀) serves as a potent antioxidant of lipid membranes. Because many antioxidants reveal potent anti-inflammatory effects, the influence of QH₂ on lipopolysaccharide (LPS)-induced pro-inflammatory cytokines and chemokines were determined in the human monocytic cell line THP-1. Stimulation of cells with LPS resulted in a distinct release of Tumour necrosis factor-alpha (TNF-α), Macrophage inflammatory protein-1 alpha (MIP-1α), Regulated upon activation, normal T cell expressed and secreted (RANTES) and Monocyte chemotattractant protein-1 (MCP-1). The LPS-induced responses were significantly decreased by pre-incubation of cells with QH₂ to 60.27 ± 9.3% (p = 0.0009), 48.13 ± 6.93% (p = 0.0007) and 74.36 ± 7.25% (p = 0.008) for TNF-α, MIP-1α and RANTES, respectively. In conclusion, our results indicate anti-inflammatory effects of the reduced form of CoQ₁₀ on various proinflammatory cytokines and chemokines in vitro.

Environmental toxicity, redox signaling and lung inflammation: the role of glutathione

Glutathione (gamma-glutamyl-cysteinyl-glycine, GSH) is the most abundant intracellular antioxidant thiol and is central to redox defense during oxidative stress. GSH metabolism is tightly regulated and has been implicated in redox signaling and also in protection against environmental oxidant-mediated injury. Changes in the ratio of the reduced and disulfide form (GSH/GSSG) can affect signaling pathways that participate in a broad array of physiological responses from cell proliferation, autophagy and apoptosis to gene expression that involve H(2)O(2) as a second messenger. Oxidative stress due to oxidant/antioxidant imbalance and also due to environmental oxidants is an important component during inflammation and respiratory diseases such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, acute respiratory distress syndrome, and asthma. It is known to activate multiple stress kinase pathways and redox-sensitive transcription factors such as Nrf2, NF-kappaB and AP-1, which differentially regulate the genes for pro-inflammatory cytokines as well as the protective antioxidant genes. Understanding the regulatory mechanisms for the induction of antioxidants, such as GSH, versus pro-inflammatory mediators at sites of oxidant-directed injuries may allow for the development of novel therapies which will allow pharmacological manipulation of GSH synthesis during inflammation and oxidative injury. This article features the current knowledge about the role of GSH in redox signaling, GSH biosynthesis and particularly the regulation of transcription factor Nrf2 by GSH and downstream signaling during oxidative stress and inflammation in various pulmonary diseases. We also discussed the current therapeutic clinical trials using GSH and other thiol compounds, such as N-acetyl-l-cysteine, fudosteine, carbocysteine, erdosteine in environment-induced airways disease.

Mechanisms of Dimethyl Sulfoxide Augmentation of IL-1β Production

Expression of the inflammatory cytokine IL-1beta occurs in various inflammatory diseases, and IL-1beta production is regulated at multiple levels. There are conflicting reports about the effects of antioxidants on IL-1beta production. In this study, we investigated the regulatory role of the antioxidant DMSO on LPS-stimulated IL-1beta gene expression in human PBMC and in vivo. This study demonstrated that 1% DMSO increased LPS-stimulated (50 ng/ml) IL-1beta secretion in a dose- and time-dependent manner without altering TNF or IL-6. DMSO also elevated IL-1beta secretion by PBMC in response to exogenous superoxide anions. Despite the increase in IL-1beta, there was no augmentation of NF-kappaB with the addition of DMSO. The steady state mRNA coding for IL-1beta following LPS stimulation was also increased. Cycloheximide studies demonstrated that the DMSO augmentation of IL-1beta mRNA did not require de novo protein synthesis, and studies with actinomycin D showed that DMSO did not alter the half-life of IL-1beta mRNA, suggesting that DMSO did not change the stability of IL-1beta mRNA. Experiments using a reporter vector containing the 5'-flanking region of the human IL-1beta gene revealed that DMSO augmented LPS-induced IL-1beta reporter activity. In vivo, treatment of mice with DMSO significantly increased plasma levels of IL-1beta after endotoxin challenge. These data indicate that DMSO directly increases LPS-stimulated IL-1beta protein production through the mechanisms of augmenting promoter activity and increasing mRNA levels.

Glutathione, stress responses, and redox signaling in lung inflammation

Changes in the ratio of intracellular reduced and disulfide forms of glutathione (GSH/GSSG) can affect signaling pathways that participate in various physiological responses from cell proliferation to gene expression and apoptosis. It is also now known that many proteins have a highly conserved cysteine (sulfhydryl) sequence in their active/regulatory sites, which are primary targets of oxidative modifications and thus important components of redox signaling. However, the mechanism by which oxidants and GSH/protein-cysteine-thiols actually participate in redox signaling still remains to be elucidated. Initial studies involving the role of cysteine in various proteins have revealed that cysteine-SH may mediate redox signaling via reversible or irreversible oxidative modification to Cys-sulfenate or Cys-sulfinate and Cys-sulfonate species, respectively. Oxidative stress possibly via the modification of cysteine residues activates multiple stress kinase pathways and transcription factors nuclear factor-kappaB and activator protein-1, which differentially regulate the genes for proinflammatory cytokines as well as the protective antioxidant genes. Understanding the redox signaling mechanisms for differential gene regulation may allow for the development of novel pharmacological approaches that preferentially up-regulate key antioxidants genes, which, in turn, reduce or resolve inflammation and injury. This forum article features the current knowledge on the role of GSH in redox signaling, particularly the regulation of transcription factors and downstream signaling in lung inflammation.

The Role of Oxidative Stress in the Pathogenesis??of COPD

Chronic inflammation and oxidative stress are important features in the pathogenesis of COPD. The increased oxidative stress in patients with COPD is the result of an increased burden of inhaled oxidants, as well as increased amounts of reactive oxygen species (ROS) generated by various inflammatory, immune and epithelial cells of the airways. Oxidative stress has important implications on several events of lung physiology and for the pathogenesis of COPD. These include oxidative inactivation of antiproteases and surfactants, mucus hypersecretion, membrane lipid peroxidation, mitochondrial respiration, alveolar epithelial injury, remodeling of extracellular matrix, and apoptosis. An increased level of ROS produced in the airways is reflected by increased markers of oxidative stress in the airspaces, sputum, breath, lungs, and blood in patients with COPD. The biomarkers of oxidative stress such as H2O2, F2-isoprostanes, malondialdehyde and 4-hydroxy-2-nonenal have been successfully measured in breath condensate. ROS and aldehydes play a key role in enhancing the inflammation through the activation of mitogen-activated protein kinases and redox-sensitive transcription factors such as nuclear factor kappa B and activator protein-1. Oxidative stress also alters nuclear histone acetylation and deacetylation leading to increased gene expression of pro-inflammatory mediators in the lung. Oxidative stress may play a role in the poor clinical efficacy of corticosteroids in the treatment of COPD. Since a variety of oxidants, free radicals, and aldehydes are implicated in the pathogenesis of COPD it is likely that a combination of antioxidants may be effective in the treatment of COPD. Antioxidant compounds may also be of therapeutic value in monitoring oxidative biomarkers indicating disease progression. Various approaches to enhance the lung antioxidant screen and the clinical effectiveness of antioxidant compounds in the treatment of COPD are discussed.

L-gamma-Glutamyl-L-cysteinyl-glycine (glutathione; GSH) and GSH-related enzymes in the regulation of pro- and anti-inflammatory cytokines: a signaling transcriptional scenario for redox(y) immunologic sensor(s)?

Of the antioxidant/prooxidant mechanisms mediating the regulation of inflammatory mediators, particularly cytokines, oxidative stress-related pathways remain a cornerstone. It is conspicuous that there is a strong association between free radical accumulation (ROS/RNS; oxidative stress) and the evolution of inflammation and inflammatory-related responses. The scenario that upholds a consensus on the aforementioned is still evolving to unravel, from an immunologic perspective, the molecular mechanisms associated with ROS/RNS-dependent inflammation. Cytokines are keynote players when it comes to defining an intimate relationship among reduction-oxidation (redox) signals, oxidative stress and inflammation. How close we are to identifying the molecular basis of this intricate association should be weighed against the involvement of specific signaling molecules and, potentially, transcription factors. L-gamma-Glutamyl-L-cysteinyl-glycine, or glutathione (GSH), an antioxidant thiol, has shaped, and still is refining, the face of oxidative signaling in terms of regulating the milieu of inflammatory mediators, ostensibly via the modulation (expression/repression) of oxygen- and redox-responsive transcription factors, hence termed redox(y)-sensitive cofactors. When it comes to the arena of oxygen sensing, oxidative stress and inflammation, nuclear factor-kappaB (NF-kappaB) and hypoxia-inducible factor-1alpha (HIF-1alpha) are key players that determine antioxidant/prooxidant responses with oxidative challenge. It is the theme therein to underlie current understanding of the molecular association hanging between oxidative stress and the evolution of inflammation, walked through an elaborate discussion on the role of transcription factors and cofactors. Would that classify glutathione and other redox signaling cofactors as potential anti-inflammatory molecules emphatically remains of particular interest, especially in the light of identifying upstream and downstream molecular pathways for conceiving therapeutic, alleviating strategy for oxidant-mediated, inflammatory-related disease conditions.

Redox modulation of chromatin remodeling: impact on histone acetylation and deacetylation, NF-kappaB and pro-inflammatory gene expression

Reactive oxygen species (ROS), either directly or via the formation of lipid peroxidation products, such as 4-hydroxy-2-nonenal, acrolein and F2-isoprostanes, may play a role in enhancing inflammation through the activation and phosphorylation of stress kinases (JNK, ERK, p38) and redox-sensitive transcription factors such as NF-kappaB and AP-1. This increases the expression of genes regulating a battery of distinct pro-inflammatory mediators. Acetylation by histone acetyltransferase (HAT) of specific lysine residues on the N-terminal tail of core histones, results in uncoiling of the DNA and increased accessibility to transcription factor binding. In contrast, histone deacetylation by histone deacetylase (HDAC) represses gene transcription by promoting DNA winding thereby limiting access to transcription factors. Oxidative stress activates NF-kappaB resulting in expression of pro-inflammatory mediators through the activation of intrinsic HAT activity on co-activator molecules. In addition, oxidative stress also inhibits HDAC activity and in doing so enhances inflammatory gene expression which leads to a chronic inflammatory response. Oxidative stress can also increase complex formation between the co-activator CBP/p300 and the p65 subunit of NF-kappaB suggesting a further role of oxidative stress in chromatin remodeling. The antioxidant and/or anti-inflammatory effects of thiol molecules (glutathione, N-acetyl-L-cysteine and N-acystelyn), dietary polyphenols (curcumin-diferuloylmethane and resveratrol), the bronchodilator theophylline and glucocorticoids have all been shown to play a role in either controlling NF-kappaB activation or chromatin remodeling through modulation of HDAC activity and subsequently inflammatory gene expression in lung epithelial cells. Thus, oxidative stress regulates both signal transduction and chromatin remodeling which in turn impacts on pro-inflammatory responses in the lungs.

Inhibition of lipopolysaccharide-induced inducible nitric oxide synthase expression by a novel compound, mercaptopyrazine, through suppression of nuclear factor-kappaB binding to DNA

Macrophage cells in response to cytokines and endotoxins produced a large amount of nitric oxide (NO) by expression of inducible nitric oxide synthase (iNOS), resulting in acute or chronic inflammatory disorders including septic hypotension and atherosclerosis. In the present study, we investigated the effect and the mechanism of mercaptopyrazine (MP) in the induction of iNOS and NO production as a culminating factor for several inflammatory disorders. Pretreatment of MP alleviated the mortality of endotoxemic mice receiving a lethal bolus of lipopolysaccharide (LPS), which was associated with the reduced levels of serum nitrite/nitrate and IL-1beta. In RAW264.7 mouse macrophage cells, MP (300microM) inhibited both protein and mRNA levels of iNOS stimulated by LPS/interferon-gamma (IFNgamma) up to 50%. The nuclear factor-kappa B (NF-kappaB)-driven transactivation was also suppressed by MP to the same degree. Treatment of MP reduced the binding of NF-kappaB to the oligonucleotides containing NF-kappaB consensus sequence, while it did not affect the translocation of NF-kappaB to nuclear. Suppression of NF-kappaB activity by MP was completely reversed by a reducing agent, dithiothreitol, implying that MP might oxidize the sulfhydryl group(s) of DNA binding domain of NF-kappaB. In conclusion, MP would be one of interesting candidates or chemical moieties of iNOS expression inhibitor via specific suppression of NF-kappaB binding to DNA, and be useful as a chemopreventive agent or a therapeutic against iNOS-associated inflammatory diseases.

Regulation of LPS-mediated inflammation in vivo and in vitro by the thiol antioxidant Nacystelyn

Increased levels of proinflammatory cytokines are present in bronchoalveolar lavage fluid in various lung diseases. Redox-sensitive transcription factors such as NF-kappaB regulate gene transcription for these cytokines. We therefore studied the effect of a new thiol antioxidant compound, Nacystelyn (NAL), on IL-8 regulation in a human macrophage-derived cell line (THP-1). LPS (10 microg/ml) increased IL-8 release compared with control levels. This LPS activation was inhibited by coincubation with NAL (1 and 5 mM). Pretreatment with cycloheximide or okadaic acid, protein synthesis, and serine/threonine phosphatase inhibitors, respectively, did not modify inhibition of IL-8 release caused by NAL. NF-kappaB and C/EBP DNA binding were increased after LPS treatment compared with control, an effect inhibited by cotreatment with NAL. Activator protein (AP)-1 DNA binding was unaffected. The enhanced neutrophil chemotaxis produced by conditioned media from LPS-treated cells was inhibited when cells were cotreated with NAL. The selectivity of NAL inhibition upon IL-8 expression was studied. LPS-treated THP-1 cells also had higher levels of TNF-alpha, transforming growth factor (TGF)-beta1 and -3, MIP-1alpha and -beta, and RANTES gene expression. However, only LPS-induced IL-8 and TGF-beta1 expressions were inhibited by NAL. An anti-inflammatory effect of NAL was confirmed in vivo as shown by a reduction in LPS-induced neutrophil recruitment to the lungs following instillation of NAL into the lungs. Our studies demonstrate that NAL has anti-inflammatory properties in vitro and in vivo, may therefore have a therapeutic role in lung inflammation, and has the advantage over other antioxidant agents in that it may be administrated by inhalation.

Evidence that glutathione depletion is a mechanism responsible for the anti-inflammatory effects of ethyl pyruvate in cultured lipopolysaccharide-stimulated RAW 264.7 cells

Ethyl pyruvate (EP), an effective scavenger of reactive oxygen species, is also an anti-inflammatory agent in a variety of in vivo and in vitro model systems. To gain a better understanding of the molecular basis for the anti-inflammatory effects of EP, we compared the pharmacological properties of EP andN-acetyl-l-cysteine (NAC), a well studied scavenger of reactive oxygen species and a precursor for the endogenous antioxidant glutathione (GSH). The studies were performed using RAW 264.7 murine macrophage-like cells that were stimulated with lipopolysaccharide (LPS). Although EP and NAC both inhibited LPS-induced nitric oxide and interleukin (IL)-6 secretion, the former compound was considerably more potent than the latter. EP markedly inhibited inducible nitric-oxide synthase, IL-6, and IL-10 mRNA induction, whereas the effects of NAC were minimal. EP inhibited LPS-induced nuclear factor-kappaB DNA binding to a much greater extent than did NAC. Both compounds inhibited LPS-induced lipid peroxidation, but the two compounds had qualitatively different effects on cellular levels of GSH. Although NAC increased GSH levels, EP had the opposite effect. The anti-inflammatory effects of EP were partially reversed when RAW 264.7 cells were treated with a cell-permeable GSH analog, glutathione ethyl ester. These data support the view that the anti-inflammatory effects of EP are mediated, at least in part, by the ability of EP to deplete cellular GSH stores. Moreover, the findings presented here suggest that an unusual combination of biochemical effects (inhibition of lipid peroxidation and GSH depletion) might account for the anti-inflammatory effects of EP.

Inhibition of lipopolysaccharide-inducible nitric oxide synthase, TNF-alpha and COX-2 expression by sauchinone effects on I-kappaBalpha phosphorylation, C/EBP and AP-1 activation

1. Sauchinone, a lignan isolated from Saururus chinensis (Saururaceae), is a diastereomeric lignan with cytoprotective and antioxidant activities in cultured hepatocytes. The effects of sauchinone on the inducible nitric oxide synthase (iNOS), tumor necrosis factor-alpha (TNF-alpha) and cyclooxygenase 2 (COX-2) gene expression and on the activation of transcription factors, nuclear factor-kappaB (NF-kappaB), CCAAT/enhancer-binding protein (C/EBP), activator protein-1 (AP-1) and cAMP-response element-binding protein (CREB) were determined in Raw264.7 cells as part of the studies on its anti-inflammatory effects. 2. Expression of the iNOS, TNF-alpha and COX-2 genes was assessed by Northern and Western blot analyses. NO production was monitored by chemiluminescence detection using a NO analyzer. To identify the transcriptional factors affected by sauchinone, the extents of NF-kappaB, C/EBP, AP-1 and CREB activation were measured. Activation of the transcription factors was monitored by gel mobility shift assay, whereas p65 and I-kappaBalpha were analyzed by immunocytochemical and immunoblot analyses. 3. Sauchinone inhibited the induction of iNOS, TNF-alpha and COX-2 by lipopolysaccharide (LPS) (IC50</=10 micro M) with suppression of the mRNAs. 4. Sauchinone (1-30 micro M) inhibited LPS-inducible nuclear NF-kappaB activation and nuclear translocation of p65, which was accompanied by inhibition of I-kappaBalpha phosphorylation. 5. LPS-inducible increase in the intensity of C/EBP binding to its consensus sequence was also inhibited by sauchinone. The AP-1, but not CREB, DNA binding activity was weakly inhibited by sauchinone. 6. These results demonstrate that sauchinone inhibits LPS-inducible iNOS, TNF-alpha and COX-2 expression in macrophages through suppression of I-kappaBalpha phosphorylation and p65 nuclear translocation and of C/EBP and/or AP-1 activation, which may constitute anti-inflammatory effects of the lignan.

Potentiation of lipopolysaccharide-inducible cyclooxygenase 2 expression by C2-ceramide via c-Jun N-terminal kinase-mediated activation of CCAAT/enhancer binding protein beta in macrophages

Ceramide, formed by sphingomyelinase, is involved in the expression of cyclooxygenase-2 (COX-2). This study examines the effect of C2-ceramide (C2), a cell-permeable ceramide analog, on the lipopolysaccharide (LPS)-inducible COX-2 expression and signaling pathways. C2 did not induce COX-2 but potentiated LPS-inducible COX-2 expression in Raw264.7 cells, whereas dihydro-C2 was inactive. Treatment of cells with C2 notably increased LPS-inducible CCAAT/enhancer binding protein (C/EBP) DNA binding. Antibody supershift experiments revealed that LPS-induced C/EBP DNA binding activity depended on C/EBP beta and C/EBP delta but not C/EBP alpha, C/EBP epsilon or CBP/p300. C/EBP beta contributed to C2-enhanced DNA binding activity. 4-(4-Fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl) 1H-imidazole (SB203580), a p38 kinase inhibitor, completely inhibited LPS-inducible and C2-potentiated LPS-inducible COX-2 expression. Enhancement of LPS-inducible COX-2 expression and C/EBP DNA binding by C2 was abrogated in dominant-negative mutant of JNK1 [JNK1(-)] cells. 2'-Amino-3'-methoxyflavone (PD98059) or stable transfection with dominant-negative mutant of MKK1 decreased COX-2 induction by LPS but failed to inhibit C2-enhanced LPS induction of COX-2. Transfection with dominant-negative mutant of C/EBP inhibited the ability of C2 to potentiate the induction of COX-2 by LPS. In LPS-treated cells, C2 enhanced both the nuclear translocation and the expression of LPS-inducible C/EBP beta with an increase in AP-1 DNA binding activity. These enhancements were abolished by JNK1(-) transfection. AP-1 decoy oligonucleotide suppressed C2-potentiated C/EBP beta expression, indicating that AP-1 was responsible for C2-mediated C/EBP beta expression. These results demonstrate that C2 increases C/EBP beta-mediated COX-2 induction by LPS and that the pathway of JNK1 but not ERK1/2 is responsible for C/EBP beta activation involving activator protein-1-mediated enhanced C/EBP beta expression.

Antioxidant and prooxidant mechanisms in the regulation of redox(y)-sensitive transcription factors

A progressive rise of oxidative stress due to the altered reduction-oxidation (redox) homeostasis appears to be one of the hallmarks of the processes that regulate gene transcription in physiology and pathophysiology. Reactive oxygen (ROS) and nitrogen (RNS) species serve as signaling messengers for the evolution and perpetuation of the inflammatory process that is often associated with the condition of oxidative stress, which involves genetic regulation. Changes in the pattern of gene expression through ROS/RNS-sensitive regulatory transcription factors are crucial components of the machinery that determines cellular responses to oxidative/redox conditions. Transcription factors that are directly influenced by reactive species and pro-inflammatory signals include nuclear factor-kappaB (NF-kappaB) and hypoxia-inducible factor-1alpha (HIF-1alpha). Here, I describe the basic components of the intracellular oxidative/redox control machinery and its crucial regulation of oxygen- and redox-sensitive transcription factors such as NF-kappaB and HIF-1alpha.

Pharmaco-redox regulation of cytokine-related pathways: from receptor signaling to pharmacogenomics

Cytokines represent a multi-diverse family of polypeptide regulators; they are relatively low molecular weight (< 30 kDa), pharmacologically active proteins that are secreted by one cell for the purpose of altering either its own functions (autocrine effect) or those of adjacent cells (paracrine effect). Cytokines are small, nonenzymatic glycoproteins whose actions are both diverse and overlapping (specificity/redundancy) and may affect diverse and overlapping target cell populations. In many instances, individual cytokines have multiple biological activities. Different cytokines can also have the same activity, which provides for functional redundancy (network) within the inflammatory and immune systems. As biological cofactors that are released by specific cells, cytokines have specific effects on cell-cell interaction, communication, and behavior of other cells. As a result, it is infrequent that loss or neutralization of one cytokine will markedly interfere with either of these systems. The biological effect of one cytokine is often modified or augmented by another. Because an interdigitating, redundant network of cytokines is involved in the production of most biological effects, both under physiologic and pathologic conditions, it usually requires more than a single defect in the network to alter drastically the outcome of the process. This fact, therefore, may have crucial significance in the development of therapeutic strategies for biopharmacologic intervention in cytokine-mediated inflammatory processes and infections.

Oxygen homeostasis, thiol equilibrium and redox regulation of signalling transcription factors in the alveolar epithelium

There is growing evidence linking the pathophysiology of lung disease to an imbalance state of reduction-oxidation (redox) equilibrium. The therapeutic potential of glutathione, an ubiquitous sulfhydryl thiol, and its immunopharmacological properties in the airway epithelium bears clinical consequences for the paediatric treatment of respiratory distress (RD). Dynamic variation in alveolar pO(2) and its effect on redox state may impose a direct role in modulating the pattern of gene expression in lung tissues and, accordingly, could be pivotal in determining cellular fate under these conditions. Hypoxia-inducible factor-1alpha (HIF-1alpha) and nuclear factor-kappaB (NF-kappaB) are redox-sensitive transcription factors of particular importance because their differential activation by reducing and oxidizing signals, respectively, regulate the expression/suppression of O(2)-responsive genes. The regulation of these transcription factors, therefore, which is redox sensitive, is consistent with their roles in coordinating adaptive homeostatic responses to oxidative stress. Functionally, the relationship between O(2), glutathione biosynthesis and transcription factor activity bears typical implications for the pattern of cellular survivorship and alveolarization on exposure to O(2)-linked stresses. In this review, I discuss (1) the HIF-1alpha/NF-kappaB responsiveness to dynamic changes in pO(2) characteristic of the transition period from placental to pulmonary-based respiration, (2) the capacity of the alveolar epithelium to engage in glutathione biosynthesis and redox shuttling, effectively forming a feedback mechanism governing gene expression, (3) the restitution of antioxidant/prooxidant equilibrium following oxidative challenge and its dependency on the adaptive coordination of responses between redox-associated signalling pathways controlling apoptosis and genetic regulatory factors and (4) a likely association between oxidative stress and the evolution of an inflammatory signal through the pleiotropic O(2)-sensitive cytokines.

Redox signaling-mediated regulation of lipopolysaccharide-induced proinflammatory cytokine biosynthesis in alveolar epithelial cells

The regulation of cytokine gene transcription and biosynthesis involves the reduction-oxidation (redox)-sensitive nuclear factor-kappaB (NF-kappaB), whose activation is mediated by an upstream kinase that regulates the phosphorylation of inhibitory-kappaB (IkappaB). It was hypothesized that lipopolysaccharide (LPS)-induced biosynthesis of interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha in vitro is regulated by redox equilibrium. In alveolar epithelial cells, we investigated the role of L-buthionine-(S,R)-sulfoximine (BSO), an irreversible inhibitor of gamma-glutamylcysteine synthetase, the rate-limiting enzyme in GSH biosynthesis, 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), which inhibits glutathione oxidized disulfide reductase, pyrrolidine dithiocarbamate (PDTC), an antioxidant/prooxidant thiuram, and N-acetyl-L-cysteine (NAC), an antioxidant and GSH precursor, in regulating LPS-induced cytokine biosynthesis and IkappaB-alpha/NF-kappaB signaling. BSO blockaded the phosphorylation of IkappaB-alpha, reduced its degradation, and inhibited NF-kappaB activation, besides augmenting LPS-mediated biosynthesis of cytokines. BCNU up-regulated LPS-induced release of cytokines, an effect associated with partial phosphorylation/degradation of IkappaB-alpha and inhibition of the DNA binding activity. PDTC, which partially affected LPS-induced IkappaB-alpha phosphorylation/degradation, otherwise blockading NF-kappaB activation, reduced LPS-dependent up-regulation of cytokine release. Pretreatment with BSO did not abolish the NAC-dependent reduction of LPS-induced cytokine release, despite the fact that NAC marginally amplified IkappaB-alpha phosphorylation/degradation and suppressed NF-kappaB activation. These results indicate that cytokines are redox-sensitive mediators and that the IkappaB-alpha/NF-kappaB pathway is redox-sensitive and differentially implicated in mediating redox-dependent regulation of LPS-induced release of proinflammatory cytokines.

Potent inhibition of lipopolysaccharide-inducible nitric oxide synthase expression by dibenzylbutyrolactone lignans through inhibition of I-kappaBalpha phosphorylation and of p65 nuclear translocation in macrophages

AIMS

Arctigenin and demethyltraxillagenin, dibenzylbutyrolactone lignans, are phenylpropanoid metabolites with antioxidant and anti-inflammatory activities. The effects of arctigenin and demethyltraxillagenin on the nuclear factor-kappaB (NF-kappaB)-mediated inducible nitric oxide synthase (iNOS, EC1.14.13.39) gene expression were studied in Raw264.7 cells.

METHODS

Activation of NF-kappaB was determined by gel mobility shift assay, immunocytochemistry and immunoblot analysis of I-kappaBalpha. Expression of the iNOS gene was assessed by Northern and Western blot analyses. NO production was monitored by chemiluminescent detection using a nitric oxide analyzer.

RESULTS

Arctigenin (1 microM) inhibited lipopolysaccharide (LPS)-inducible nuclear NF-kappaB activation and nuclear translocation of p65, which was accompanied by inhibition of I-kappaBalpha phosphorylation, whereas demethyltraxillagenin was less active. LPS-inducible increase in the iNOS mRNA was 80-90% inhibited by 0.01-1 microM arctigenin, whereas similar extents of inhibition were noted by 50-100 microM demethyltraxillagenin. Immunoblot analysis revealed that arctigenin potently inhibited the induction of iNOS by LPS (IC50 < 0.01 microM). The IC50 value of demethyltraxillagenin was approximately 50 microM. Production of nitrite and nitrate by LPS in culture medium was also comparably suppressed by the lignans.

CONCLUSION

These results demonstrated that arctigenin potently inhibited LPS-inducible iNOS expression in murine macrophages through suppression of I-kappaBalpha phosphorylation and nuclear translocation of p65. Potent inhibition of LPS-inducible NO production in macrophages may constitute anti-inflammatory effects of the dibenzylbutyrolactone lignans.