Pranlukast inhibits NF-kappaB activation and MUC2 gene expression in cultured human epithelial cells

Benzopyrone, a privileged scaffold in drug discovery: An overview of FDA-approved drugs and clinical candidates

Natural products have always served as an important source of drugs for treating various diseases. Among various privileged natural product scaffolds, the benzopyrone class of compounds has a substantial presence among biologically active compounds. One of the pioneering anticoagulant drugs, warfarin approved in 1954 bears a benzo-α-pyrone (coumarin) nucleus. The widely investigated psoriasis drugs, methoxsalen, and trioxsalen, also contain a benzo-α-pyrone nucleus. Benzo-γ-pyrone (chromone) containing drugs, cromoglic acid, and pranlukast were approved as treatments for asthma in 1982 and 2007, respectively. Numerous other small molecules with a benzopyrone core are under clinical investigation. The present review discusses the discovery, absorption, distribution, metabolism, excretion properties, and synthetic approaches for the Food and Drug Administration-approved and clinical-stage benzopyrone class of compounds. The role of the pyrone core in biological activity has also been discussed. The present review unravels the potential of benzopyrone core in medicinal chemistry and drug development.

Lipid mediators of inhalation exposure-induced pulmonary toxicity and inflammation

Many inhalation exposures induce pulmonary inflammation contributing to disease progression. Inflammatory processes are actively regulated via mediators including bioactive lipids. Bioactive lipids are potent signaling molecules involved in both pro-inflammatory and resolution processes through receptor interactions. The formation and clearance of lipid signaling mediators are controlled by multiple metabolic enzymes. An imbalance of these lipids can result in exacerbated and sustained inflammatory processes which may result in pulmonary damage and disease. Dysregulation of pulmonary bioactive lipids contribute to inflammation and pulmonary toxicity following exposures. For example, inhalation of cigarette smoke induces activation of pro-inflammatory bioactive lipids such as sphingolipids, and ceramides contributing to chronic obstructive pulmonary disease. Additionally, exposure to silver nanoparticles causes dysregulation of inflammatory resolution lipids. As inflammation is a common consequence resulting from inhaled exposures and a component of numerous diseases it represents a broadly applicable target for therapeutic intervention. With new appreciation for bioactive lipids, technological advances to reliably identify and quantify lipids have occurred. In this review, we will summarize, integrate, and discuss findings from recent studies investigating the impact of inhaled exposures on pro-inflammatory and resolution lipids within the lung and their contribution to disease. Throughout the review current knowledge gaps in our understanding of bioactive lipids and their contribution to pulmonary effects of inhaled exposures will be presented. New methods being employed to detect and quantify disruption of pulmonary lipid levels following inhalation exposures will be highlighted. Lastly, we will describe how lipid dysregulation could potentially be addressed by therapeutic strategies to address inflammation.

Regulation of the Gene Expression of Airway MUC5AC Mucin through NF-κB Signaling Pathway by Artesunate, an Antimalarial Agent

In this study, artesunate, an antimalarial agent, was investigated for its potential effect on the gene expression of airway MUC5AC mucin. The human pulmonary epithelial NCI-H292 cells were pretreated with artesunate for 30 min and then stimulated with phorbol 12-myristate 13-acetate (PMA), for the following 24 h. The effect of artesunate on PMA-induced nuclear factor kappa B (NF-kB) signaling pathway was also examined. Artesunate inhibited the glycoprotein production and mRNA expression of MUC5AC mucins, induced by PMA through the inhibition of degradation of inhibitory kappa Bα (IkBα) and NF-kB p65 nuclear translocation. These results suggest artesunate suppresses the gene expression of mucin through regulation of NF-kB signaling pathway, in human pulmonary epithelial cells.

Small Molecules as Toll-like Receptor 4 Modulators Drug and In-House Computational Repurposing

The innate immunity toll-like receptor 4 (TLR4) system is a receptor of paramount importance as a therapeutic target. Virtual screening following a “computer-aided drug repurposing” approach was applied to the discovery of novel TLR4 modulators with a non-lipopolysaccharide-like structure. We screened almost 29,000 approved drugs and drug-like molecules from commercial, public, and in-house academia chemical libraries and, after biological assays, identified several compounds with TLR4 antagonist activity. Our computational protocol showed to be a robust approach for the identification of hits with drug-like scaffolds as possible inhibitors of the TLR4 innate immune pathways. Our collaborative work broadens the chemical diversity for inspiration of new classes of TLR4 modulators.

Involvement of IKK/IkBα/NF-kB p65 Signaling into the Regulative Effect of Engeletin on MUC5AC Mucin Gene Expression in Human Airway Epithelial Cells

In this study, we examined whether engeletin exerts an effect on the gene expression of MUC5AC mucin, in human pulmonary epithelial NCI-H292 cells. The cells were pretreated with engeletin for 30 min and stimulated with phorbol 12-myristate 13-acetate (PMA), for the following 24 h. The effect of engeletin on PMA-induced nuclear factor kappa B (NF-kB) signaling pathway was also investigated. Engeletin suppressed the mRNA expression and production of MUC5AC mucin, induced by PMA through the inhibition of degradation of inhibitory kappa Bα (IkBα) and NF-kB p65 nuclear translocation. These results suggest engeletin inhibits the gene expression of mucin through regulation of NF-kB signaling pathway, in human airway epithelial cells.

Tussilagone protects acute lung injury from PM2.5 via alleviating Hif-1α/NF-κB-mediated inflammatory response

Environmental pollution, especially particulate matter in the air, is a serious threat to human health. Long-term inhalation of particulate matter with a diameter < 2.5 μm (PM2.5) induced irreversible respiratory and lung injury. However, it is not clear whether temporary exposure to massive PM2.5 would result in epithelial damage and lung injury. More importantly, it is urgent to clarify the mechanisms of PM2.5 cytotoxicity and develop a defensive and therapeutic approach. In this study, we demonstrated that temporary exposure with PM2.5 induced lung epithelial cell apoptosis via promoting cytokines expression and inflammatory factors secretion. The cytotoxicity of PM2.5 could be alleviated by tussilagone (TSL), which is a natural compound isolated from the flower buds of Tussilago farfara. The mechanism study indicated that PM2.5 promoted the protein level of Hif-1α by reducing its degradation mediated by PHD2 binding, which furtherly activated NF-κB signaling and inflammatory response. Meanwhile, TSL administration facilitated the interaction of the Hif-1α/PHD2 complex and restored the Hif-1α protein level increased by PM2.5. When PHD2 was inhibited in epithelial cells, the protective function of TSL on PM2.5 cytotoxicity was attenuated and the expression of cytokines was retrieved. Expectedly, the in vivo study also suggested that temporary PM2.5 exposure led to acute lung injury. TSL treatment could effectively relieve the damage and decrease the expression of inflammatory cytokines by repressing Hif-1α level and NF-κB activation. Our findings provide a new therapeutic strategy for air pollution-related respiratory diseases, and TSL would be a potential preventive medicine for PM2.5 cytotoxicity.

Effects of non-steroidal anti-inflammatory drugs and other eicosanoid pathway modifiers on antiviral and allergic responses: EAACI task force on eicosanoids consensus report in times of COVID-19

Non‐steroidal anti‐inflammatory drugs (NSAIDs) and other eicosanoid pathway modifiers are among the most ubiquitously used medications in the general population. Their broad anti‐inflammatory, antipyretic, and analgesic effects are applied against symptoms of respiratory infections, including SARS‐CoV‐2, as well as in other acute and chronic inflammatory diseases that often coexist with allergy and asthma. However, the current pandemic of COVID‐19 also revealed the gaps in our understanding of their mechanism of action, selectivity, and interactions not only during viral infections and inflammation, but also in asthma exacerbations, uncontrolled allergic inflammation, and NSAIDs‐exacerbated respiratory disease (NERD). In this context, the consensus report summarizes currently available knowledge, novel discoveries, and controversies regarding the use of NSAIDs in COVID‐19, and the role of NSAIDs in asthma and viral asthma exacerbations. We also describe here novel mechanisms of action of leukotriene receptor antagonists (LTRAs), outline how to predict responses to LTRA therapy and discuss a potential role of LTRA therapy in COVID‐19 treatment. Moreover, we discuss interactions of novel T2 biologicals and other eicosanoid pathway modifiers on the horizon, such as prostaglandin D2 antagonists and cannabinoids, with eicosanoid pathways, in context of viral infections and exacerbations of asthma and allergic diseases. Finally, we identify and summarize the major knowledge gaps and unmet needs in current eicosanoid research.

Eriodictyol Inhibits the Production and Gene Expression of MUC5AC Mucin via the IκBα-NF-κB p65 Signaling Pathway in Airway Epithelial Cells

In this study, we investigated whether eriodictyol exerts an effect on the production and gene expression of MUC5AC mucin in human pulmonary epithelial NCI-H292 cells. The cells were pretreated with eriodictyol for 30 min and then stimulated with phorbol 12-myristate 13-acetate (PMA) for 24 h. The effect of eriodictyol on PMA-induced nuclear factor kappa B (NF-κB) signaling pathway was also investigated. Eriodictyol suppressed the MUC5AC mucin production and gene expression induced by PMA via suppression of inhibitory kappa Bα degradation and NF-κB p65 nuclear translocation. These results suggest that eriodictyol inhibits mucin gene expression and production in human airway epithelial cells via regulation of the NF-κB signaling pathway.

Expression profiling of ileal mucosa in asthma reveals upregulation of innate immunity and genes characteristic of Paneth and goblet cells

Background

The expression profiles of the intestinal mucosa have not been comprehensively investigated in asthma. We aimed to explore this in the Correlated Expression and Disease Association Research (CEDAR) patient cohort.

Methods

Differential expression analysis of ileal, transverse colon, and rectal biopsies were supplemented by a comparison of transcriptomes from platelets and leukocytes subsets, including CD4+, CD8+, CD14+, CD15+, and CD19+ cells. Asthma patients (n = 15) and controls (n = 15) had similar age (p = 0.967), body mass index (p = 0.870), similar numbers of females (80%) and smoking rates (13.3%).

Results

Significant differential expression was found in the ileum alone, and not in any other cell/tissue types. More genes were found to be overexpressed (1,150) than under-expressed (380). The most overexpressed genes included Fc Fragment of IgG Binding Protein (FCGBP, logFC = 3.01, pFDR = 0.015), Mucin 2 (MUC2, logFC = 2.78, pFDR = 0.015), and Alpha 1B Defensin (DEFA1B, logFC = 2.73, pFDR = 0.024). Gene ontology implicated the immune system, including interleukins 4 and 13, as well as antimicrobial peptides in this overexpression. There was concordance of gene over- (STAT1, XBP1) and underexpression (NELF, RARA) in asthma and Crohn’s disease ileum when our results were compared to another dataset (p = 3.66 × 10^–7).

Conclusion

Ileal mucosa in asthma exhibits a specific transcriptomic profile, which includes the overexpression of innate immune genes, mostly characteristic of Paneth and goblet cells, in addition to other changes that may resemble Crohn’s disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-021-00584-9.

Kaempferol Regulates the Expression of Airway MUC5AC Mucin Gene via IκBα-NF-κB p65 and p38-p44/42-Sp1 Signaling Pathways

In the present study, kaempferol, a flavonoidal natural compound found in Polygonati Rhizoma, was investigated for its potential effect on the gene expression and production of airway MUC5AC mucin. A human respiratory epithelial NCI-H292 cells was pretreated with kaempferol for 30 min and stimulated with epidermal growth factor (EGF) or phorbol 12-myristate 13-acetate (PMA), for the following 24 h. The effect on PMA-induced nuclear factor kappa B (NF-κB) signaling pathway or EGF-induced mitogen-activated protein kinase (MAPK) signaling pathway was investigated. Kaempferol suppressed the production and gene expression of MUC5AC mucins, induced by PMA through the inhibition of degradation of inhibitory kappa Bα (IκBα), and NF-κB p65 nuclear translocation. Also, kaempferol inhibited EGF-induced gene expression and production of MUC5AC mucin through regulating the phosphorylation of EGFR, phosphorylation of p38 MAPK and extracellular signal-regulated kinase (ERK) 1/2 (p44/42), and the nuclear expression of specificity protein-1 (Sp1). These results suggest kaempferol regulates the gene expression and production of mucin through regulation of NF-κB and MAPK signaling pathways, in human airway epithelial cells.

Diclofenac Inhibits Phorbol Ester-Induced Gene Expression and Production of MUC5AC Mucin via Affecting Degradation of IkBα and Translocation of NF-kB p65 in NCI-H292 Cells

In this study, diclofenac, a non-steroidal anti-inflammatory drug, was investigated for its potential effect on the gene expression and production of airway MUC5AC mucin. The human respiratory epithelial NCI-H292 cells were pretreated with diclofenac for 30 min and stimulated with phorbol 12-myristate 13-acetate (PMA), for the following 24 h. The effect of diclofenac on PMA-induced nuclear factor kappa B (NF-kB) signaling pathway was also investigated. Diclofenac suppressed the production and gene expression of MUC5AC mucins, induced by PMA through the inhibition of degradation of inhibitory kappa Bα (IkBα) and NF-kB p65 nuclear translocation. These results suggest diclofenac regulates the gene expression and production of mucin through regulation of NF-kB signaling pathway, in human airway epithelial cells.

Obtusifolin isolated from the seeds of Cassia obtusifolia regulates the gene expression and production of MUC5AC mucin in airway epithelial cells via affecting NF-κB pathway

We investigated whether obtusin, obtusifolin, and cassiaside isolated from the seeds of Cassia obtusifolia inhibit the gene expression and production of airway mucin 5AC (MUC5AC). Confluent NCI-H292 cells were pretreated with obtusin, obtusifolin, or cassiaside for 30 min and then stimulated with epidermal growth factor (EGF), phorbol 12-myristate 13-acetate (PMA), or tumor necrosis factor-α (TNF-α) for 24 hr. The MUC5AC mucin gene expression was measured by reverse transcription-polymerase chain reaction. Production of MUC5AC mucin protein was measured by enzyme-linked immunosorbent assay. To elucidate the action mechanism of obtusifolin, effect of obtusifolin on PMA-induced nuclear factor kappa B (NF-κB) signaling pathway was investigated by western blot analysis. Obtusin, obtusifolin, or cassiaside inhibited the expression of MUC5AC mucin gene and the production of MUC5AC mucin protein, induced by EGF, PMA, or TNF-α. Obtusifolin inhibited PMA-induced activation (phosphorylation) of inhibitory kappa B kinase, and thus phosphorylation and degradation of inhibitory kappa B alpha. Obtusifolin inhibited PMA-induced nuclear translocation of NF-κB p65. These results suggest that obtusifolin can regulate the production and gene expression of mucin by acting on airway epithelial cells through regulation of NF-κB signaling pathway.

Tussilagone suppressed the production and gene expression of MUC5AC mucin via regulating nuclear factor-kappa B signaling pathway in airway epithelial cells

In the present study, we investigated whether tussilagone, a natural product derived from Tussilago farfara, significantly affects the production and gene expression of airway MUC5AC mucin. Confluent NCI-H292 cells were pretreated with tussilagone for 30 min and then stimulated with EGF (epidermal growth factor) or PMA (phorbol 12-myristate 13-acetate) for 24 h or the indicated periods. The MUC5AC mucin gene expression was measured by RT-PCR. Production of MUC5AC mucin protein was measured by ELISA. To elucidate the action mechanism of tussilagone, effect of tussilagone on PMA-induced NF-κB signaling pathway was investigated by western blot analysis. Tussilagone significantly inhibited the production of MUC5AC mucin protein and down-regulated the expression of MUC5AC mucin gene, induced by EGF or PMA. Tussilagone inhibited PMA-induced activation (phosphorylation) of inhibitory kappa B kinase (IKK), and thus phosphorylation and degradation of inhibitory kappa Ba (IκBα). Tussilagone inhibited PMA-induced phosphorylation and nuclear translocation of nuclear factor kappa B (NF-κB) p65. This, in turn, led to the down-regulation of MUC5AC protein production in NCI-H292 cells. These results suggest that tussilagone can regulate the production and gene expression of mucin by acting on airway epithelial cells through regulation of NF-κB signaling pathway.

The cytosolic sensor STING is required for intestinal homeostasis and control of inflammation

STING (stimulator of interferon genes) is a cytosolic sensor for cyclic dinucleotides and also an adaptor molecule for intracellular DNA receptors. Although STING has important functions in the host defense against pathogens and in autoimmune diseases, its physiological relevance in intestinal homeostasis is largely unknown. In this study, we show that STING^-/- mice presented defective protective mechanisms of intestinal mucosa, including decreased number of goblet cells, diminished mucus production, and lower levels of secretory IgA, when compared with wild-type (WT) mice. Fecal content and microbiota DNA could activate STING, indicating a role of this molecule in gut. Microbiota composition was altered in STING^-/- mice toward a more inflammatory profile, evidencing a reduction in the Allobacolum and Bifidobacterium groups along with increase in Disulfovibrio bacteria. Absence of STING lead to decrease in induced intraepithelial lymphocytes (IEL) and to increase in group 1 innate lymphoid cell (ILC1) as well as ILC3 frequencies and decrease in ILC2 in the colon. Development and function of Foxp3+ and LAP+ regulatory T cells were also compromised in STING^-/- mice. Moreover, these mice were highly susceptible to dextran sodium sulfate-induced colitis, T-cell-induced colitis, and enteric Salmonella typhimurium infection when compared with WT animals. Therefore, our results identify an important role of STING in maintaining gut homeostasis and also a protective effect in controlling gut inflammation.

Mometasone Furoate Suppresses PMA-Induced MUC-5AC and MUC-2 Production in Human Airway Epithelial Cells

BACKGROUND

Mucus hypersecretion from airway epithelium is a characteristic feature of airway inflammatory diseases. Tumor necrosis factor α (TNF-α) regulates mucin synthesis. Glucocorticoids including mometasone fuorate (MF) have been used to attenuate airway inflammation. However, effects of MF on mucin production have not been reported.

METHODS

Effects of MF and budesonide (BUD) on the phorbol-12-myristate-13-acetate (PMA)-induction of mucin and TNF-α in human airway epithelial cells (NCI-H292) were investigated in the present study. Confluent NCI-H292 cells were pretreated with PMA (200 nM) for 2 hours. Subsequently, the cells were stimulated with MF (1-500 ng/mL) or BUD (21.5 ng/mL) for 8 hours. Dexamethasone (1 µg/mL) was used as the positive control. Real-time polymerase chain reaction was used to determine MUC2 and MUC5AC mRNA levels. The level of total mucin, MUC2, MUC5AC, and TNF-α in culture supernatants were measured using enzyme-linked immunosorbent assay.

RESULTS

MF and BUD significantly suppressed MUC2 and MUC5AC gene expression in PMA-stimulated NCI-H292 cells. The inhibitory effects of the two steroid drugs were also observed in the production of total mucin, MUC2 and MUC5AC proteins, and TNF-α.

CONCLUSION

Our findings demonstrated that MF and BUD attenuated mucin and TNF-α production in PMA-induced human airway epithelial cells.

Leukotriene E4 induces MUC5AC release from human airway epithelial NCI-H292 cells

BACKGROUND

Hypersecretion of mucin in the airway epithelium is an important feature of allergic airway diseases. Of the 3 cysteinyl leukotrienes (CysLTs; LTC4 LTD4 and LTE4), only LTE4 is sufficiently stable to be detectable in extracellular fluids. However, LTE4 has received little attention because it binds poorly to the CysLT1 and CysLT2 receptors; therefore, little is known about the effects of LTE4 on mucous secretion. Recently, studies have focused on the P2Y12 receptor as a potential receptor for LTE4, because this receptor is required for LTE4-mediated pulmonary inflammation. In our previous study, we confirmed the expression of P2Y12 receptor in human airway epithelial cells. To clarify the roles of LTE4 in airway epithelial cells, we investigated mucus secretion by LTE4 in vitro.

METHODS

Confluent NCI-H292 cells were stimulated with LTE4 (0.01-1 μM) for 24 h. The release and production of MUC5AC protein, a gel-forming mucin, were evaluated with an enzyme-linked immunosorbent assay.

RESULTS

Western blot analysis revealed that NCI-H292 cells expressed P2Y12 receptor protein. LTE4 significantly induced the release of MUC5AC mucin in a dose-dependent manner. Th2 cytokines such as IL-4 (10 ng/mL) and IL-13 (10 ng/mL) accelerated the LTE4-induced release of MUC5AC protein. MRS2935, a P2Y12 receptor antagonist, partially inhibited the LTE4-induced release of MUC5AC protein in the airway. In contrast, MK571, a CysLT1 receptor antagonist, did not affect the release of MUC5AC protein elicited by LTE4.

CONCLUSIONS

These results suggest that LTE4 may play some important roles in allergic mucus secretion partially via activation of P2Y12 receptor.

Macrolides attenuate phorbol ester-induced tumor necrosis factor-α and mucin production from human airway epithelial cells

BACKGROUND/AIMS

Macrolide antibiotics are effective drugs in chronic bronchiolitis and chronic rhinosinusitis with mucus hypersecretion. However, the mechanism of action is unclear. This study was designed to investigate the effect of azithromycin (AZM; 15-membered) and midecamycin acetate (MDM; 16-membered) on MUC5AC and MUC2 gene expression and secretion from human airway epithelial cells. The effects of the two macrolides on tumor necrosis factor-α (TNF-α) release were also examined.

METHODS

Confluent NCI-H292 human mucoepidermoid airways epithelial cells were pretreated with AZM or MDM for 2 h and then stimulated with 200 nmol/l phorbol 12-myristate 13-acetate (PMA) for 8 h. The MUC5AC and MUC2 gene expression was measured by real-time quantitative RT-PCR. Total mucin in culture supernatants was measured using enzyme-linked lectin assay. Enzyme-linked immunosorbent assay was used to determine MUC5AC, MUC2 and TNF-α released by the cells.

RESULTS

AZM and MDM attenuated PMA-induced MUC5AC and MUC2 gene and protein expression in NCI-H292 cells. They also suppressed PMA-mediated TNF-α in the cells.

CONCLUSION

The present study demonstrates that AZM and MDM suppress the synthesis of mucin and TNF-α from human airway epithelial cells.

A co-module approach for elucidating drug-disease associations and revealing their molecular basis

MOTIVATION

Understanding how drugs and diseases are associated in the molecular level is of critical importance to unveil disease mechanisms and treatments. Until recently, few studies attempt end to discover important gene modules shared by both drugs and diseases.

RESULTS

Here, we propose a novel presentation of drug-gene-disease relationship, a 'co-module', which is characterized by closely related drugs, diseases and genes. We first define a network-based gene closeness profile to relate drug to disease. Then, we develop a Bayesian partition method to identify drug-gene-disease co-modules underlying the gene closeness data. Genes share similar notable patterns with respect not only to the drugs but also the diseases within a co-module. Simulations show that our method, comCIPHER, achieves a better performance compared with a popular co-module detection method, PPA. We apply comCIPHER to a set consisting of 723 drugs, 275 diseases and 1442 genes and demonstrate that our co-module approach is able to identify new drug-disease associations and highlight their molecular basis. Disease co-morbidity emerges as well. Three co-modules are further illustrated in which new drug applications, including the anti-cancer metastasis activity of an anti-asthma drug Pranlukast, and a cardiovascular stress-testing agent Arbutamine for obesity, as well as potential side-effects, e.g. hypotension for Triamterene, are computationally identified.

AVAILABILITY

The compiled version of comCIPHER can be found at http://bioinfo.au.tsinghua.edu.cn/comCIPHER/. The 86 co-modules can be downloaded from http://bioinfo.au.tsinghua.edu.cn/comCIPHER/Co_Module_Results.zip.

CONTACT

shaoli@mail.tsinghua.edu.cn

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Pranlukast attenuates hydrogen peroxide-induced necrosis in endothelial cells by inhibiting oxygen reactive species-mediated collapse of mitochondrial membrane potential

OBJECTIVE

Recently, we reported that pranlukast, an antagonist of cysteinyl leukotriene receptor 1, attenuates ischemic injury in endothelial cells by decreasing reactive oxygen species (ROS) production and inhibiting nuclear factor-κB activation in a leukotriene-independent manner. In this study, we investigated the effect of pranlukast on oxidative stress injury induced by hydrogen peroxide (H2O2) in EA.hy926 cells, a human endothelial cell line, and the possible mechanisms.

METHODS AND RESULTS

We found that H2O2 reduced cell viability and increased lactate dehydrogenase release in a concentration- and time-dependent manner. Necrosis was the main death mode, and the necrotic rate increased 32% after exposure to 220 μM H2O2 for 4 hours. Pretreatment with pranlukast significantly ameliorated the reduced viability and the increased lactate dehydrogenase release and necrosis after exposure to H2O2. We next examined the mechanisms underlying the antinecrotic effects of pranlukast. The results showed that pranlukast attenuated excessive ROS production and ameliorated the reduced superoxide dismuase and glutathione peroxidase activity in EA.hy926 cells exposed to H2O2. Pranlukast also inhibited the collapse of mitochondrial membrane potential (MMP) induced by H2O2. Inhibition of ROS production by N-acetyl-l-cysteine, a powerful antioxidant, reduced MMP collapse and necrosis. Inhibition of MMP collapse by cyclosporine A, a mitochondrial permeability transition inhibitor, attenuated necrosis but failed to reduce ROS production. In addition, we found no expression of 5-lipoxygenase in EA.hy926 cells and zileuton, a 5-lipoxygenase inhibitor, did not affect the cellular injury induced by H2O2.

CONCLUSION

Pranlukast protects endothelial cells from H2O2-induced necrosis by inhibiting ROS-mediated collapse of mitochondrial membrane potential, and this is leukotriene-independent.

Montelukast, a cysteinyl leukotriene receptor-1 antagonist, attenuates chronic brain injury after focal cerebral ischaemia in mice and rats

OBJECTIVES

Previously we demonstrated the neuroprotective effect of montelukast, a cysteinyl leukotriene receptor-1 (CysLT(1) ) antagonist, on acute brain injury after focal cerebral ischaemia in mice. In this study, we have determined its effect on chronic brain injury after focal cerebral ischaemia in mice and rats.

METHODS

After transient focal cerebral ischaemia was induced by middle cerebral artery occlusion, montelukast was intraperitoneally injected in mice or orally administered to rats for five days. Behavioural dysfunction, brain infarct volume, brain atrophy and neuron loss were determined to evaluate brain lesions.

KEY FINDINGS

Montelukast (0.1 mg/kg) attenuated behavioural dysfunction, brain infarct volume, brain atrophy and neuron loss in mice, which was similar to pranlukast, another CysLT(1) receptor antagonist. Oral montelukast (0.5 mg/kg) was effective in rats and was more effective than edaravone, a free radical scavenger.

CONCLUSION

Montelukast protected mice and rats against chronic brain injury after focal cerebral ischaemia, supporting the therapeutic potential of CysLT(1) receptor antagonists.

What's new in asthma pathophysiology and immunopathology?

Research on asthma pathophysiology over the past decade has expanded the complex repertoire involved in the pathophysiology of asthma to include inflammatory, immune and structural cells, as well as a wide range of mediators. Studies have identified a role for connective and other mesenchymal tissues involved in airway remodeling. Recent findings have implicated the innate immune response in asthma and have revealed interesting patterns of interaction between the innate and adaptive immune response and the associated complex chronic inflammatory reaction. New immune cell populations have also been added to this repertoire, including Tregs, natural killer T cells and Th17 cells. The role of the eosinophil, a prominent pathological feature in most asthma phenotypes, has also been expanding to include roles such as tissue modifiers and immune regulators via a number of fascinating and hitherto unexplored mechanistic pathways. In addition, new and significant roles have been proposed for airway smooth muscle cells, fibroblasts, epithelial and endothelial cells. Tissue remodeling is now considered an integral element of asthma pathophysiology. Finally, an intricate network of mediators, released from both immune and inflammatory cells, including thymus stromal lymphopoietin and matrix metalloproteinases, have added to the complex milieu of asthma immunity and inflammation. These findings have implications for therapy and the search for novel strategies towards better disease management. Sadly, and perhaps due to the complex nature of asthma, advances in therapeutic discoveries and developments have been limited. Thus, understanding the precise roles played by the numerous dramatis personae in this odyssey, both individually and collectively within the context of asthma pathophysiology, continues to pose new challenges. It is clear that the next stage in this saga is to embark on studies that transcend reductionist approaches to involve system analysis of the complex and multiple variables involved in asthma, including the need to narrow down the phenotypes of this condition based on careful analysis of the organs (lung and airways), cells, mediators and other factors involved in bronchial asthma.

Pranlukast attenuates ischemia-like injury in endothelial cells via inhibiting reactive oxygen species production and nuclear factor-kappaB activation

The anti-inflammatory effects of pranlukast, an antagonist of cysteinyl leukotriene receptor 1, may be rendered not only by antileukotriene activity but also by other pharmacological activities. Previous studies indicate that pranlukast reduces ischemic tissue injury partially through decreasing vascular permeability, but its effect on ischemic injury in endothelial cells is not known. Thus, in this study, we investigated the effect of pranlukast on ischemia-like injury induced by oxygen-glucose deprivation (OGD) in EA.hy926 cells, a human endothelial cell line, and the possible mechanisms. We found that cell viability was reduced, lactate dehydrogenase release was increased 4-8 hours after OGD, and necrosis was induced 8 hours after OGD. Production of reactive oxygen species (ROS) increased by 211%, 176%, and 128%, respectively, 0.5, 1, and 2 hours after OGD. Nuclear factor-kappaB (NF-kappaB) was translocated to the nuclei 4-8 hours after OGD. Pranlukast ameliorated the reduced viability, the increased lactate dehydrogenase release, and necrosis after OGD. It also reduced ROS production and inhibited NF-kappaB nuclear translocation after OGD. The ROS scavenger, edaravone, inhibited OGD-induced nuclear translocation of NF-kappaB as well. Edaravone and pyrrolidine dithiocarbamate (a specific NF-kappaB inhibitor) protected endothelial cells from the OGD-induced injury. However, zileuton, a 5-lipoxygenase inhibitor, did not affect the cell injury, ROS production, and NF-kappaB nuclear translocation after OGD. The exogenous leukotriene D4 did not induce cell injury, ROS production, and NF-kappaB translocation. Thus, we conclude that pranlukast protects endothelial cells from ischemia-like injury via decreasing ROS production and inhibiting NF-kappaB activation, which is leukotriene independent.

Cysteinyl-leukotriene receptor antagonism blunts the acute hypotensive response to endotoxin in cats

This study evaluated the effects of a cysteinyl-leukotriene-1 (cys-LT(1)) receptor antagonist, zarfirlukast, during feline endotoxemia. Six adult, sexually intact male cats received either placebo or zarfirlukast (10mg, PO) and endotoxin (2 μg/kg/h q 6h) in a cross-over design. Rectal temperature, heart rate, systolic arterial blood pressure, plasma tumor necrosis factor (TNF) activity, interleukin (IL)-6 concentration and urine cys-LT to creatinine ratio were evaluated. The rectal temperature, plasma TNF activity and IL-6 concentrations were significantly higher and systolic arterial blood pressure and heart rate significantly lower after endotoxin infusion. Cats treated with zafirlukast had a significantly higher blood pressure at 4h (P=0.002) compared to placebo. Urine cys-LT to creatinine ratio was significantly greater in the cats treated with zafirlukast compared to placebo (P=0.02). Zafirlukast administration ameliorated the acute hypotensive response to endotoxin in cats, but failed to significantly alter rectal temperature, heart rate or production of TNF and IL-6.

Opposing roles of leukotrienes and prostaglandins in fibrotic lung disease

Lung fibrosis is a devastating disease that involves a variable degree of inflammation, alveolar epithelial injury, fibroblast hyperplasia and the deposition of extracellular matrix. Standard therapies that consist of corticosteroids and immunosuppressive agents offer little benefit and most patients experience a progressive deterioration in lung function which is ultimately fatal within 2-5 years of diagnosis. New pathogenetic insights and therapeutic approaches are badly needed. Eicosanoids are lipid mediators derived from arachidonic acid metabolism, the best studied of which are prostaglandins and leukotrienes. Although these mediators are primarily known for their roles in asthma, pain, fever and vascular responses, they also exert relevant effects on immune and inflammatory cells as well as structural cells such as epithelial cells and fibroblasts - cell types which participate in fibrogenesis. In general, leukotrienes promote while prostaglandin E(2) opposes fibrogenic responses. Lung fibrosis is associated with increased production of leukotrienes and decreased production of prostaglandin E(2). Furthermore, responses to prostaglandin E(2) are altered in fibrotic conditions. This review highlights the role of this leukotriene/prostaglandin imbalance in the evolution of fibrotic lung disease, offers insights into the mechanisms that underlie the dysregulated responses and discusses approaches for therapeutic targeting of eicosanoids in these conditions.

Montelukast inhibits tumour necrosis factor-alpha-mediated interleukin-8 expression through inhibition of nuclear factor-kappaB p65-associated histone acetyltransferase activity

BACKGROUND

Montelukast is a potent cysteinyl leukotriene-1 receptor antagonist possessing some anti-inflammatory effects although the molecular mechanism of these anti-inflammatory effects is unknown. In this study, we aimed to investigate the effect of montelukast on nuclear factor (NF)-kappaB-associated histone acetylation activity in phorbol myristate acetate (PMA)-differentiated U937 cells.

METHODS

We examined the inhibitory effects of montelukast on TNF-alpha-induced IL-8 production in PMA-differentiated U-937 cells. U-937 cells were exposed to PMA (50 ng/mL) for 48 h to allow differentiation to macrophages. Macrophages were then exposed to TNF-alpha (10 ng/mL) in the presence or absence of montelukast (0.01-10 microm) for 24 h. After this time, the concentration of IL-8 in the culture supernatant was measured by sandwich-type ELISA kit. The effect of signalling pathways on TNF-alpha-induced IL-8 release was examined pharmacologically using selective NF-kappaB/IKK2 (AS602868, 3 microm), (PD98059, 10 microm) and p38 mitogen activated protein kinase (MAPK) (SB203580, 1 microm) inhibitors. NF-kappaB DNA binding activity was measured by a DNA-binding ELISA-based assay. NF-kappaB-p65-associated histone acetyltransferase (HAT) activity was measured by immunoprecipitation linked to commercial fluorescent HAT.

RESULTS

TNF-alpha-induced IL-8 release was suppressed by an NF-kappaB inhibitor but not by MEK or p38 MAPK inhibitors. Montelukast induced a concentration-dependent inhibition of TNF-alpha-induced IL-8 release and mRNA expression that reached a plateau at 0.1 microm without affecting cell viability. Montelukast did not affect NF-kappaB p65 activation as measured by DNA binding but suppressed NF-kappaB p65-associated HAT activity.

CONCLUSION

Montelukast inhibits TNF-alpha-stimulated IL-8 expression through changes in NF-kappaB p65-associated HAT activity. Drugs targeting these enzymes may enhance the anti-inflammatory actions of montelukast.

Interaction of Toll-like receptors with bacterial components induces expression of CDX2 and MUC2 in rat biliary epithelium in vivo and in culture

The mechanism of transformation of biliary epithelium leading to intestinal metaplasia, which is significantly involved in biliary diseases, remains unclear. CDX2, an intestine-specific transcription factor, is thought to regulate intestinal mucin MUC2 (mucus core protein) expression. We took advantage of polycystic kidney (PCK) rats as a model of chronic suppurative cholangitis with intestinal metaplasia and of cultured biliary epithelial cells (BECs) from PCK rats to clarify the causal relation between bacterial components such as pathogen-associated molecular patterns (PAMPs) and the development of intestinal metaplasia of bile ducts. Histological, immunohistochemical, and in situ hybridization studies were conducted in PCK rat livers. In cultured BECs, CDX2 and MUC2 were expressed following treatment with PAMPs and inhibitors (anti-Toll-like receptor (TLR)2/TLR4 antibody, nuclear factor-kappaB (NF-kappaB) inhibitor MG132). Chronic suppurative cholangitis with intestinal metaplasia developed as the PCK rats aged, and intestinal metaplasia and aberrant CDX2 and MUC2 expression developed in parallel. Intraluminal bacteria and the expression of TLR2 and TLR4 in BECs were demonstrated in the bile ducts, showing chronic suppurative cholangitis. In cultured BECs, treatment with PAMPs induced upregulation of CDX2 and MUC2 expression, and this effect was abolished by pretreatment with anti-TLR2 and anti-TLR4 antibody and MG132. A knockdown of CDX2 by CDX2 small interfering RNA inhibited MUC2 expression in cultured BECs induced by PAMPs, and transfection of CDX2 expression vector induced MUC2 expression. In conclusion, bacterial components may induce upregulation of the CDX2 expression followed by MUC2 expression via TLR and the NF-kappaB system in cultured BECs, and could be related to the development of intestinal metaplasia of the bile ducts.

The inhibitory effect of the leukotriene receptor antagonist on leukotriene D4-induced MUC2/5AC gene expression and mucin secretion in human airway epithelial cells

OBJECTIVES

Mucin gene expression and mucin production are markedly increased in inflammatory airway disorders such as asthma, chronic bronchitis and rhinosinusitis. Cytokines, lipopolysaccharides and other inflammatory mediators such as prostaglandin and leukotriene are related to the secretion and production of mucin. However, the relationship of leukotrienes with mucin genes expression is not clear. The aim of this study is to evaluate MUC2/5AC gene expression and mucin secretion by the leukotriene receptor in human airway epithelial cells.

METHODS

The effect of leukotriene D(4) and the leukotriene receptor antagonist, pranlukast hydrate (ONO-1078) on the regulation of MUC2/5AC gene expression and mucin secretion were observed in human airway NCI-H292 epithelial cells. The mRNA levels of MUC2/5AC and the amount of mucin were determined by reverse transcription-polymerase chain reaction (RT-PCR) and immunoassay.

RESULTS

Leukotriene D(4) upregulated MUC2/5AC gene expression and mucin secretion in a dose dependent pattern. Pranlukast hydrate (ONO-1078, 100 microM) downregulated the leukotriene D(4)-induced MUC2/5AC gene expression and mucin secretion.

CONCLUSION

These results suggest that the leukotriene receptor system is one of the mechanisms related to MUC2/5AC gene expression and mucin secretion in the human airway epithelium.

CysLT1 receptor engagement induces activator protein-1- and NF-kappaB-dependent IL-8 expression

Because cysteinyl-leukotrienes (cysLTs) are major protagonists in the pathophysiology of human asthma, and because neutrophils are involved in the more severe form of asthma, we studied the potential for leukotriene (LT) D(4) to induce synthesis of the chemokine IL-8 through activation of the CysLT1 receptor. We found LTD(4) to induce IL-8 gene expression in monocytic THP-1 cells and human dendritic cells with complete abrogation by selective CysLT1 antagonists. Human embryonic kidney-293 cells stably transfected with CysLT1 were used to better study the transcriptional regulation of the IL-8 promoter. Stimulation of the cells with graded concentrations of LTD(4) resulted in a time- and concentration-dependent induction of IL-8 transcription and protein synthesis. Use of IL-8 promoter mutants with substitutions in their NF-kappaB, activator protein (AP)-1, and NF-IL-6 binding elements revealed a requirement for NF-kappaB and AP-1, but not NF-IL-6, in LTD(4)-induced activation of the IL-8 promoter. Overexpression of dominant-negative IkappaBalpha inhibited the IL-8 transactivation induced by LTD(4). NF-kappaB DNA binding activity was induced by LTD(4), as determined by electrophoretic mobility shift assays, and could be supershifted by antibodies against p50 and p65. Supershift assays after LTD(4) stimulation also indicated the formation of a c-Jun/c-Fos complex. Moreover, our results demonstrate that LTD(4) upregulates the expression of c-fos and c-jun at the mRNA level. Our data show for the first time that LTD(4), via the CysLT1 receptor, can transcriptionally activate IL-8 production, with involvement of the transcription factors p50, p65, Fos, and Jun. These findings provide mechanistic and potentially therapeutic elements for modulation of the inflammatory component of asthma.

Mucus and MUC in asthma

PURPOSE OF REVIEW

Asthma is characterized by chronic airway inflammation and a mucus hypersecretory phenotype comprising excess mucus secretion, goblet cell hyperplasia and submucosal gland hypertrophy. This augmented mucus secretion has been relatively undervalued in asthma compared with airway inflammation. However, mucus plugging contributes to airflow limitation and airway hyperresponsiveness, and to morbidity and mortality in asthma. We review recent contributions to this field and therapeutic avenues to control mucus hypersecretion.

RECENT FINDINGS

A distinct mucus hypersecretory phenotype may present in asthma. Overexpression of MUC5AC, MUC5B and MUC2 have been described in asthma secretions, but identification of defined biochemical abnormalities and polymorphisms of mucin genes linked to asthma remains elusive. Activation of epidermal growth factor receptor (EGFR) activation appears central in transducing many different stimuli, including oxidative stress, proteases and cytokines. In contrast, nitrosative stress has barely been investigated. The existence of crosstalk between EGFR and other receptor systems may provide new clues regarding the activity of acetylcholine, adenosine and other agonists of G-protein-coupled receptors and other receptor families on mucin secretion. Modern techniques for noninvasive detection of mucus pathology will advance clinical research in this field.

SUMMARY

Airway mucus hypersecretion as a part of airway remodelling represents a problem in asthma, and studies of pathophysiology and therapeutic approaches are therefore warranted. Identification of targets such as the EGFR cascade, which are crucial in excessive and abnormal mucus secretion, may lead to the rational design of new antihypersecretory drugs that may enhance future asthma treatment.

Leukotrienes modulate cytokine release from dendritic cells

Leukotriene B(4) (LTB(4)) and cysteinyl leukotrienes (CysLTs) are known as potent mediators of inflammation, whereas their role in the regulation of adaptive immunity remains poorly characterized. Dendritic cells (DCs) are specialized antigen-presenting cells, uniquely capable to initiate primary immune responses. We have found that zymosan, but not lipopolysaccharide (LPS) stimulates murine bone marrow-derived dendritic cells (BM-DCs) to produce large amounts of CysLTs and LTB(4) from endogenous substrates. A selective inhibitor of leukotriene synthesis MK886 as well as an antagonist of the high affinity LTB(4) receptor (BLT(1)) U-75302 slightly inhibited zymosan-, but not LPS-stimulated interleukin (IL)-10 release from BM-DCs. In contrast, U-75302 increased zymosan-stimulated release of IL-12 p40 by approximately 23%. Pre-treatment with transforming growth factor-beta1 enhanced both stimulated leukotriene synthesis and the inhibitory effect of U-75302 and MK886 on IL-10 release from DCs. Consistent with the effects of leukotriene antagonists, exogenous LTB(4) enhanced LPS-stimulated IL-10 release by approximately 39% and inhibited IL-12 p40 release by approximately 22%. Both effects were mediated by the BLT(1) receptor. Ligands of the high affinity CysLTs receptor (CysLT(1)), MK-571 and LTD(4) had little or no effect on cytokine release. Agonists of the nuclear LTB(4) receptor peroxisome proliferator-activated receptor-alpha, 8(S)-hydroxyeicosatetraenoic acid and 5,8,11,14-eicosatetraynoic acid, inhibited release of both IL-12 p40 and IL-10. Our results indicate that both autocrine and paracrine leukotrienes may modulate cytokine release from DCs, in a manner that is consistent with previously reported T helper 2-polarizing effects of leukotrienes.