Validation of the anti-inflammatory properties of small-molecule IkappaB Kinase (IKK)-2 inhibitors by comparison with adenoviral-mediated delivery of dominant-negative IKK1 and IKK2 in human airways smooth muscle

Prospects of neutrophilic implications against pathobiology of chronic obstructive pulmonary disease: Pharmacological insights and technological advances

Chronic obstructive pulmonary disease (COPD) is a prevalent chronic inflammatory condition that affects the lungs globally. A key feature of this inflammatory response is the migration and aggregation of polymorphonuclear neutrophils (PMNs). The presence of neutrophilic inflammation within the airways is as distinguishing characteristic of COPD. As research advances, PMNs and their products emerge as central players in the airway inflammatory cascade of COPD patients. Their involvement in phagocytosis, degranulation, and the formation of neutrophil extracellular traps (NETs) significantly contributes to the pathogenesis of COPD. Moreover, studies have shown that excessive biological activities of neutrophils in the lungs can result in airway epithelial injury, emphysema, and mucus hypersecretion. Currently, there is growing empirical support for the moderate targeting neutrophils in the clinical management of COPD. This article delves into the pivotal role of neutrophils in COPD, emphasizing the urgency for novel therapeutic approaches that specifically target neutrophils. Additionally, it explores the potential of utilizing single-cell RNA sequencing to further investigate neutrophils and relevant risk genes as potential biomarkers for COPD treatment. By elucidating these mechanisms, this review aims to pave the way for future strategies to modulate neutrophil function, thereby addressing the pressing need for more effective COPD therapies.

Multifaceted Roles of Chemokine C-X-C Motif Ligand 7 in Inflammatory Diseases and Cancer

Over recent years, C-X-C motif ligand 7 (CXCL7) has received widespread attention as a chemokine involved in inflammatory responses. Abnormal production of the chemokine CXCL7 has been identified in different inflammatory diseases; nevertheless, the exact role of CXCL7 in the pathogenesis of inflammatory diseases is not fully understood. Persistent infection or chronic inflammation can induce tumorigenesis and progression. Previous studies have shown that the pro-inflammatory chemokine CXCL7 is also expressed by malignant tumor cells and that binding of CXCL7 to its cognate receptors C-X-C chemokine receptor 1 (CXCR1) and C-X-C chemokine receptor 2 (CXCR2) can influence tumor biological behavior (proliferation, invasion, metastasis, and tumor angiogenesis) in an autocrine and paracrine manner. CXCL7 and its receptor CXCR1/CXCR2, which are aberrantly expressed in tumors, may represent new targets for clinical tumor immunotherapy.

Progress in the mechanism and targeted drug therapy for COPD

Chronic obstructive pulmonary disease (COPD) is emphysema and/or chronic bronchitis characterised by long-term breathing problems and poor airflow. The prevalence of COPD has increased over the last decade and the drugs most commonly used to treat it, such as glucocorticoids and bronchodilators, have significant therapeutic effects; however, they also cause side effects, including infection and immunosuppression. Here we reviewed the pathogenesis and progression of COPD and elaborated on the effects and mechanisms of newly developed molecular targeted COPD therapeutic drugs. Among these new drugs, we focussed on thioredoxin (Trx). Trx effectively prevents the progression of COPD by regulating redox status and protease/anti-protease balance, blocking the NF-κB and MAPK signalling pathways, suppressing the activation and migration of inflammatory cells and the production of cytokines, inhibiting the synthesis and the activation of adhesion factors and growth factors, and controlling the cAMP-PKA and PI3K/Akt signalling pathways. The mechanism by which Trx affects COPD is different from glucocorticoid-based mechanisms which regulate the inflammatory reaction in association with suppressing immune responses. In addition, Trx also improves the insensitivity of COPD to steroids by inhibiting the production and internalisation of macrophage migration inhibitory factor (MIF). Taken together, these findings suggest that Trx may be the ideal drug for treating COPD.

Important lessons learned from studies on the pharmacology of glucocorticoids in human airway smooth muscle cells: Too much of a good thing may be a problem

Glucocorticoids (GCs) are the treatment of choice for chronic inflammatory diseases such as asthma. Despite proven effective anti-inflammatory and immunosuppressive effects, long-term and/or systemic use of GCs can potentially induce adverse effects. Strikingly, some recent experimental evidence suggests that GCs may even exacerbate some disease outcomes. In asthma, airway smooth muscle (ASM) cells are among the targets of GC therapy and have emerged as key contributors not only to bronchoconstriction, but also to airway inflammation and remodeling, as implied by experimental and clinical evidence. We here will review the beneficial effects of GCs on ASM cells, emphasizing the differential nature of GC effects on pro-inflammatory genes and on other features associated with asthma pathogenesis. We will also summarize evidence describing how GCs can potentially promote pro-inflammatory and remodeling features in asthma with a specific focus on ASM cells. Finally, some of the possible solutions to overcome these unanticipated effects of GCs will be discussed.

Involvement of inhibitor kappa B kinase 2 (IKK2) in the regulation of vascular tone

Inhibitor kappa B kinase 2 (IKK2) plays an essential role in the activation of nuclear factor kappa B (NF-kB). Recently, it has been suggested that IKK2 acts as a myosin light chain kinase (MLCK) and contributes to vasoconstriction in mouse aorta. However, the underlying mechanisms are still unknown. Therefore, we investigated whether IKK2 acts as a MLCK or regulates the activity of myosin light chain phosphatase (MLCP). Pressure myograph was used to measure vascular tone in rat mesenteric arteries. Immunofluorescence staining was performed to identify phosphorylation levels of MLC (ser19), MYPT1 (thr853 and thr696) and CPI-17 (thr38). SC-514 (IKK2 inhibitor, 50 μM) induced relaxation in the mesenteric arteries pre-contracted with 70 mM high K⁺ solution or U-46619 (thromboxane analog, 5 μM). The relaxation induced by SC-514 was increased in the arteries pre-contracted with U-46619 compared to arteries pre-contracted with 70 mM high K⁺ solution. U-46619-induced contraction was decreased by treatment of SC-514 in the presence of MLCK inhibitor, ML-7 (10 μM). In the absence of intracellular Ca²⁺, U-46619 still induced contraction, which was decreased by treatment of SC-514. Furthermore, phosphorylation levels of MLC (ser19) and MYPT1 (thr853) were decreased by treatment of SC-514. IKK2 is involved in the vascular contraction through regulation of MLCP activity by phosphorylating MYPT1 at thr853 in rat mesenteric arteries. These findings suggest IKK2 could be a new pharmacological target for specific therapies of various vascular diseases.

New targets for resolution of airway remodeling in obstructive lung diseases

Airway remodeling (AR) is a progressive pathological feature of the obstructive lung diseases, including asthma and chronic obstructive pulmonary disease (COPD). The pathology manifests itself in the form of significant, progressive, and (to date) seemingly irreversible changes to distinct respiratory structural compartments. Consequently, AR correlates with disease severity and the gradual decline in pulmonary function associated with asthma and COPD. Although current asthma/COPD drugs manage airway contraction and inflammation, none of these effectively prevent or reverse features of AR. In this review, we provide a brief overview of the features and putative mechanisms affecting AR. We further discuss recently proposed strategies with promise for deterring or treating AR.

Propagation of respiratory viruses in human airway epithelia reveals persistent virus-specific signatures

Background

The leading cause of acute illnesses, respiratory viruses, typically cause self-limited diseases, although severe complications can occur in fragile patients. Rhinoviruses (RVs), respiratory enteroviruses (EVs), influenza virus, respiratory syncytial viruses (RSVs), and coronaviruses are highly prevalent respiratory pathogens, but because of the lack of reliable animal models, their differential pathogenesis remains poorly characterized.

Objective

We sought to compare infections by respiratory viruses isolated from clinical specimens using reconstituted human airway epithelia.

Methods

Tissues were infected with RV-A55, RV-A49, RV-B48, RV-C8, and RV-C15; respiratory EV-D68; influenza virus H3N2; RSV-B; and human coronavirus (HCoV)–OC43. Replication kinetics, cell tropism, effect on tissue integrity, and cytokine secretion were compared. Viral adaptation and tissue response were assessed through RNA sequencing.

Results

RVs, RSV-B, and HCoV-OC43 infected ciliated cells and caused no major cell death, whereas H3N2 and EV-D68 induced ciliated cell loss and tissue integrity disruption. H3N2 was also detected in rare goblet and basal cells. All viruses, except RV-B48 and HCoV-OC43, altered cilia beating and mucociliary clearance. H3N2 was the strongest cytokine inducer, and HCoV-OC43 was the weakest. Persistent infection was observed in all cases. RNA sequencing highlighted perturbation of tissue metabolism and induction of a transient but important immune response at 4 days after infection. No majority mutations emerged in the viral population.

Conclusion

Our results highlight the differential in vitro pathogenesis of respiratory viruses during the acute infection phase and their ability to persist under immune tolerance. These data help to appreciate the range of disease severity observed in vivo and the occurrence of chronic respiratory tract infections in immunocompromised hosts.

The Role of Mitochondria and Oxidative/Antioxidative Imbalance in Pathobiology of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common preventable and treatable disease, characterized by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases. The major risk factor of COPD, which has been proven in many studies, is the exposure to cigarette smoke. However, it is 15-20% of all smokers who develop COPD. This is why we should recognize the pathobiology of COPD as involving a complex interaction between several factors, including genetic vulnerability. Oxidant-antioxidant imbalance is recognized as one of the significant factors in COPD pathogenesis. Numerous exogenous and endogenous sources of ROS are present in pathobiology of COPD. One of endogenous sources of ROS is mitochondria. Although leakage of electrons from electron transport chain and forming of ROS are the effect of physiological functioning of mitochondria, there are various intra- and extracellular factors which may increase this amount and significantly contribute to oxidative-antioxidative imbalance. With the coexistence with impaired antioxidant defence, all these issues lead to oxidative and carbonyl stress. Both of these states play a significant role in pathobiology of COPD and may account for development of major comorbidities of this disease.

Kinases as Novel Therapeutic Targets in Asthma and Chronic Obstructive Pulmonary Disease

Multiple kinases play a critical role in orchestrating the chronic inflammation and structural changes in the respiratory tract of patients with asthma and chronic obstructive pulmonary disease (COPD). Kinases activate signaling pathways that lead to contraction of airway smooth muscle and release of inflammatory mediators (such as cytokines, chemokines, growth factors) as well as cell migration, activation, and proliferation. For this reason there has been great interest in the development of kinase inhibitors as anti-inflammatory therapies, particular where corticosteroids are less effective, as in severe asthma and COPD. However, it has proven difficult to develop selective kinase inhibitors that are both effective and safe after oral administration and this has led to a search for inhaled kinase inhibitors, which would reduce systemic exposure. Although many kinases have been implicated in inflammation and remodeling of airway disease, very few classes of drug have reached the stage of clinical studies in these diseases. The most promising drugs are p38 MAP kinases, isoenzyme-selective PI3-kinases, Janus-activated kinases, and Syk-kinases, and inhaled formulations of these drugs are now in development. There has also been interest in developing inhibitors that block more than one kinase, because these drugs may be more effective and with less risk of losing efficacy with time. No kinase inhibitors are yet on the market for the treatment of airway diseases, but as kinase inhibitors are improved from other therapeutic areas there is hope that these drugs may eventually prove useful in treating refractory asthma and COPD.

The effect of an IκB-kinase-β(IKKβ) inhibitor on tobacco smoke-induced pulmonary inflammation

PURPOSE OF THE STUDY

Inactivation of NF-κB with IKKβ knockout mice reduces tobacco smoke-induced pulmonary inflammation. In this study, we investigated whether the IKKβ inhibitor PS-1145 could attenuate the pulmonary inflammation induced by tobacco smoke.

MATERIALS AND METHODS

We divided 30 mice into three groups: a control group, a smoking group, and a PS-1145 group. Mice from the smoking and PS-1145 groups were exposed for 2 weeks to tobacco smoke. PS-1145 was injected intraperitoneally before every tobacco smoke exposure. After 2 weeks, bronchoalveolar lavage (BAL) was performed for cell counting and measuring of inflammatory chemokines. We analyzed the correlation between NF-κB and NF-κB-regulated chemokines in BAL fluid and measured the neutrophils and macrophages by immunostaining in lung tissues.

RESULTS

The PS-1145 group showed a significant reduction in the number of total cells, neutrophils, and macrophages, as well as the KC and MCP-1 level, in the BAL fluid compared to the smoking group. There was no significant difference in the level of MIP-1α. The level of NF-κB in BAL fluid was significantly positively correlated with KC and MCP-1 levels, but not with MIP-1α level. The PS-1145 group also showed a significant fewer neutrophils and macrophages in the lung tissue.

CONCLUSIONS

We conclude that the IKKβ inhibitor PS-1145 suppressed the NF-κB signaling pathway and reduced the recruitment of inflammatory cells and chemokines in pulmonary inflammation induced by tobacco smoke. IKKβ inhibition offers a potential therapeutic target for tobacco smoke-induced pulmonary inflammation.

NF-kappaB Signaling in Chronic Inflammatory Airway Disease

Asthma and chronic obstructive pulmonary disease (COPD) are obstructive airway disorders which differ in their underlying causes and phenotypes but overlap in patterns of pharmacological treatments. In both asthma and COPD, oxidative stress contributes to airway inflammation by inducing inflammatory gene expression. The redox-sensitive transcription factor, nuclear factor (NF)-kappaB (NF-κB), is an important participant in a broad spectrum of inflammatory networks that regulate cytokine activity in airway pathology. The anti-inflammatory actions of glucocorticoids (GCs), a mainstay treatment for asthma, involve inhibition of NF-κB induced gene transcription. Ligand bound GC receptors (GRs) bind NF-κB to suppress the transcription of NF-κB responsive genes (i.e., transrepression). However, in severe asthma and COPD, the transrepression of NF-κB by GCs is negated as a consequence of post-translational changes to GR and histones involved in chromatin remodeling. Therapeutics which target NF-κB activation, including inhibitors of IκB kinases (IKKs) are potential treatments for asthma and COPD. Furthermore, reversing GR/histone acetylation shows promise as a strategy to treat steroid refractory airway disease by augmenting NF-κB transrepression. This review examines NF-κB signaling in airway inflammation and its potential as target for treatment of asthma and COPD.

Smooth muscle CaMKIIδ promotes allergen-induced airway hyperresponsiveness and inflammation

Airway smooth muscle (ASM) is a key target cell in allergen-induced asthma known to contribute to airway hyperresponsiveness (AHR) and chronic airway remodeling. Changes in ASM calcium homeostasis have been shown to contribute to AHR although the mechanisms and Ca(2+) signal effectors are incompletely understood. In the present study, we tested the function of ASM multifunctional protein kinase Ca(2+)/calmodulin-dependent kinase II (CaMKII) isoforms CaMKIIδ and CaMKIIγ in allergen-induced AHR and airway remodeling in vivo. Using a murine model of atopic asthma, we demonstrate that CaMKIIδ protein is upregulated in ASM derived from ovalbumin (OVA)-treated animals compared to controls. A genetic approach to conditionally knock out smooth muscle CaMKIIδ and CaMKIIγ in separate Cre-loxp systems was validated, and using this loss-of-function approach, the function of these CaMKII isoforms was tested in ovalbumin (OVA)-induced airway remodeling and AHR. OVA treatment in control mice had no effect on ASM remodeling in this model of AHR, and CaMKIIδ knockouts had no independent effects on ASM content. However, at 1 day post-final OVA challenge, OVA-induced AHR was eliminated in the CaMKIIδ knockouts. OVA-induced peribronchial inflammation and bronchoalveolar lavage fluid (BALF) levels of the Th2 cytokine IL-13 were significantly decreased in the CaMKIIδ knockouts. Unexpectedly, we found increased peribronchial eosinophils in the smooth muscle CaMKIIδ knockouts compared to control animals at 1 day post-final challenge, suggesting that lack of ASM CaMKIIδ delays the progression of AHR rather than inhibiting it. Indeed, when AHR was determined at 7 days post-final OVA challenge, CaMKIIδ knockouts showed robust AHR while AHR was fully resolved in OVA-challenged control mice. These in vivo studies demonstrate a role for smooth muscle CaMKIIδ in promoting airway inflammation and AHR and suggest a complex signaling role for CaMKIIδ in regulating ASM function. These studies confirm the diverse roles of ASM cells as immune effectors that control AHR and call for further studies into CaMKIIδ-mediated signaling in ASM cells during disease.

Effect of JAK Inhibitors on Release of CXCL9, CXCL10 and CXCL11 from Human Airway Epithelial Cells

Background

CD8⁺ T-cells are located in the small airways of COPD patients and may contribute to pathophysiology. CD8⁺ cells express the chemokine receptor, CXCR3 that binds CXCL9, CXCL10 and CXCL11, which are elevated in the airways of COPD patients. These chemokines are released from airway epithelial cells via activation of receptor associated Janus kinases (JAK). This study compared the efficacy of two structurally dissimilar pan-JAK inhibitors, PF956980 and PF1367550, and the glucocorticosteroid dexamethasone, in BEAS-2B and human primary airway epithelial cells from COPD patients and control subjects.

Methods

Cells were stimulated with either IFNγ alone or with TNFα, and release of CXCL9, CXCL10 and CXCL11 measured by ELISA and expression of CXCL9, CXCL10 and CXCL11 by qPCR. Activation of JAK signalling was assessed by STAT1 phosphorylation and DNA binding.

Results

There were no differences in the levels of release of CXCL9, CXCL10 and CXCL11 from primary airway epithelial cells from any of the subjects or following stimulation with either IFNγ alone or with TNFα. Dexamethasone did not inhibit CXCR3 chemokine release from stimulated BEAS-2B or primary airway epithelial cells. However, both JAK inhibitors suppressed this response with PF1367550 being ~50-65-fold more potent than PF956980. The response of cells from COPD patients did not differ from controls with similar responses regardless of whether inhibitors were added prophylactically or concomitant with stimuli. These effects were mediated by JAK inhibition as both compounds suppressed STAT1 phosphorylation and DNA-binding of STAT1 and gene transcription.

Conclusions

These data suggest that the novel JAK inhibitor, PF1367550, is more potent than PF956980 and that JAK pathway inhibition in airway epithelium could provide an alternative anti-inflammatory approach for glucocorticosteroid-resistant diseases including COPD.

Heterogeneity in mechanisms influencing glucocorticoid sensitivity: the need for a systems biology approach to treatment of glucocorticoid-resistant inflammation

Glucocorticoids (GCs) have impressive anti-inflammatory and immunosuppressive effects and show a diversity of actions across a variety of cell phenotypes. Implicit in efforts to optimize GCs as anti-inflammatory agents for any or all indications is the notion that the relevant mechanism(s) of action of GCs are fully elucidated. However, recent advances in understanding GC signalling mechanisms have revealed remarkable complexity and contextual dependence, calling into question whether the mechanisms of action are sufficiently well-described to embark on optimization. In the current review, we address evidence for differences in the mechanism of action in different cell types and contexts, and discuss contrasts in mechanisms of glucocorticoid insensitivity, with a focus on asthma and Chronic Obstructive Pulmonary Disease (COPD). Given this complexity, we consider the potential breadth of impact and selectivity of strategies directed to reversing the glucocorticoid insensitivity.

Chronic inflammation and cancer: potential chemoprevention through nuclear factor kappa B and p53 mutual antagonism

Activation of nuclear factor-kappa B (NF- κB) as a mechanism of host defense against infection and stress is the central mediator of inflammatory responses. A normal (acute) inflammatory response is activated on urgent basis and is auto-regulated. Chronic inflammation that results due to failure in the regulatory mechanism, however, is largely considered as a critical determinant in the initiation and progression of various forms of cancer. Mechanistically, NF- κB favors this process by inducing various genes responsible for cell survival, proliferation, migration, invasion while at the same time antagonizing growth regulators including tumor suppressor p53. It has been shown by various independent investigations that a down regulation of NF- κB activity directly, or indirectly through the activation of the p53 pathway reduces tumor growth substantially. Therefore, there is a huge effort driven by many laboratories to understand the NF- κB signaling pathways to intervene the function of this crucial player in inflammation and tumorigenesis in order to find an effective inhibitor directly, or through the p53 tumor suppressor. We discuss here on the role of NF- κB in chronic inflammation and cancer, highlighting mutual antagonism between NF- κB and p53 pathways in the process. We also discuss prospective pharmacological modulators of these two pathways, including those that were already tested to affect this mutual antagonism.

Sphingosine 1-phosphate induces neutrophil chemoattractant IL-8: repression by steroids

The bioactive sphingolipid sphingosine 1-phosphate (S1P) is found in increased amounts in the airways of asthmatics. S1P can regulate airway smooth muscle functions associated with asthmatic inflammation and remodeling, including cytokine secretion. To date however, whether S1P induces secretion of an important chemokine responsible for neutrophilia in airway inflammation – IL-8 – was unexplored. The aim of this study was to investigate whether S1P induces IL-8 gene expression and secretion to enhance neutrophil chemotaxis in vitro, as well as examine the molecular mechanisms responsible for repression by the corticosteroid dexamethasone. We show that S1P upregulates IL-8 secretion from ASM cells and enhance neutrophil chemotaxis in vitro. The corticosteroid dexamethasone significantly represses IL-8 mRNA expression and protein secretion in a concentration- and time-dependent manner. Additionally, we reveal that S1P-induced IL-8 secretion is p38 MAPK and ERK-dependent and that these key phosphoproteins act on the downstream effector mitogen- and stress-activated kinase 1 (MSK1) to control secretion of the neutrophil chemoattractant cytokine IL-8. The functional relevance of this in vitro data was demonstrated by neutrophil chemotaxis assays where S1P-induced effects can be significantly attenuated by pretreatment with dexamethasone, pharmacological inhibition of p38 MAPK- or ERK-mediated pathways, or by knocking down MSK-1 with siRNA. Taken together, our study reveals the molecular pathways responsible for IL-8 secretion from ASM cells in response to S1P and indicates ways in which the impact on IL-8-driven neutrophilia may be lessened.

Anti-inflammatory dimethylfumarate: a potential new therapy for asthma?

Asthma is a chronic inflammatory disease of the airways, which results from the deregulated interaction of inflammatory cells and tissue forming cells. Beside the derangement of the epithelial cell layer, the most prominent tissue pathology of the asthmatic lung is the hypertrophy and hyperplasia of the airway smooth muscle cell (ASMC) bundles, which actively contributes to airway inflammation and remodeling. ASMCs of asthma patients secrete proinflammatory chemokines CXCL10, CCL11, and RANTES which attract immune cells into the airways and may thereby initiate inflammation. None of the available asthma drugs cures the disease—only symptoms are controlled. Dimethylfumarate (DMF) is used as an anti-inflammatory drug in psoriasis and showed promising results in phase III clinical studies in multiple sclerosis patients. In regard to asthma therapy, DMF has been anecdotally reported to reduce asthma symptoms in patients with psoriasis and asthma. Here we discuss the potential use of DMF as a novel therapy in asthma on the basis of in vitro studies of its inhibitory effect on ASMC proliferation and cytokine secretion in ASMCs.

Glucocorticoid repression of inflammatory gene expression shows differential responsiveness by transactivation- and transrepression-dependent mechanisms

Binding of glucocorticoid to the glucocorticoid receptor (GR/NR3C1) may repress inflammatory gene transcription via direct, protein synthesis-independent processes (transrepression), or by activating transcription (transactivation) of multiple anti-inflammatory/repressive factors. Using human pulmonary A549 cells, we showed that 34 out of 39 IL-1β-inducible mRNAs were repressed to varying degrees by the synthetic glucocorticoid, dexamethasone. Whilst these repressive effects were GR-dependent, they did not correlate with either the magnitude of IL-1β-inducibility or the NF-κB-dependence of the inflammatory genes. This suggests that induction by IL-1β and repression by dexamethasone are independent events. Roles for transactivation were investigated using the protein synthesis inhibitor, cycloheximide. However, cycloheximide reduced the IL-1β-dependent expression of 13 mRNAs, which, along with the 5 not showing repression by dexamethasone, were not analysed further. Of the remaining 21 inflammatory mRNAs, cycloheximide significantly attenuated the dexamethasone-dependent repression of 11 mRNAs that also showed a marked time-dependence to their repression. Such effects are consistent with repression occurring via the de novo synthesis of a new product, or products, which subsequently cause repression (i.e., repression via a transactivation mechanism). Conversely, 10 mRNAs showed completely cycloheximide-independent, and time-independent, repression by dexamethasone. This is consistent with direct GR transrepression. Importantly, the inflammatory mRNAs showing attenuated repression by dexamethasone in the presence of cycloheximide also showed a significantly greater extent of repression and a higher potency to dexamethasone compared to those mRNAs showing cycloheximide-independent repression. This suggests that the repression of inflammatory mRNAs by GR transactivation-dependent mechanisms accounts for the greatest levels of repression and the most potent repression by dexamethasone. In conclusion, our data indicate roles for both transrepression and transactivation in the glucocorticoid-dependent repression of inflammatory gene expression. However, transactivation appears to account for the more potent and efficacious mechanism of repression by glucocorticoids on these IL-1β-induced genes.

Corticosteroid resistance and novel anti-inflammatory therapies in chronic obstructive pulmonary disease: current evidence and future direction

Corticosteroids are widely used in the treatment of chronic obstructive pulmonary disease (COPD). However, in contrast to their use in mild-to-moderate asthma, they are much less effective in enhancing lung function and have little or no effect on controlling the underlying chronic inflammation. In most clinical trials in COPD patients, corticosteroids have shown little benefit as monotherapy, but have shown a greater clinical effect in combination with long-acting bronchodilators. Several mechanisms of corticosteroid resistance have been postulated, including a reduction in histone deacetylase (HDAC)-2 activity and expression, impaired corticosteroid activation of the glucocorticoid receptor (GR) and increased pro-inflammatory signalling pathways. Reversal of corticosteroid resistance in COPD patients by restoring HDAC2 levels has proved effective in a small study, and long-term studies are needed to determine whether novel HDAC2 activators or theophylline improve disease progression, exacerbations or mortality. Advances in the understanding of the cellular and molecular mechanisms of corticosteroid resistance in COPD pathophysiology have supported the development of new emerging classes of anti-inflammatory drugs in COPD treatment. These include treatments such as inhibitors of phosphoinositide-3-kinase-delta (PI3Kδ), phosphodiesterase-4 (PDE4), p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB), and therapeutic agents such as chemokine receptor antagonists. Of these, PI3Kδ, PDE4, p38 MAPK inhibitors and chemokine receptor antagonists are in clinical patient trials. Of importance, patient adverse effects associated with oral administration of these novel agents needs to be addressed in order to optimize therapy and patient compliance. Combinations of these drugs with corticosteroids may have additional benefits.

25-Hydroxycholesterol-3-sulfate attenuates inflammatory response via PPARγ signaling in human THP-1 macrophages

The nuclear receptor peroxisome proliferator-activated receptors (PPARs) are important in regulating lipid metabolism and inflammatory responses in macrophages. Activation of PPARγ represses key inflammatory response gene expressions. Recently, we identified a new cholesterol metabolite, 25-hydroxycholesterol-3-sulfate (25HC3S), as a potent regulatory molecule of lipid metabolism. In this paper, we report the effect of 25HC3S and its precursor 25-hydroxycholesterol (25HC) on PPARγ activity and on inflammatory responses. Addition of 25HC3S to human macrophages markedly increased nuclear PPARγ and cytosol IκB and decreased nuclear NF-κB protein levels. PPARγ response element reporter gene assays showed that 25HC3S significantly increased luciferase activities. PPARγ competitor assay showed that the K(i) for 25HC3S was ∼1 μM, similar to those of other known natural ligands. NF-κB-dependent promoter reporter gene assays showed that 25HC3S suppressed TNFα-induced luciferase activities only when cotransfected with pcDNAI-PPARγ plasmid. In addition, 25HC3S decreased LPS-induced expression and release of IL-1β. In the PPARγ-specific siRNA transfected macrophages or in the presence of PPARγ-specific antagonist, 25HC3S failed to increase IκB and to suppress TNFα and IL-1β expression. In contrast to 25HC3S, its precursor 25HC, a known liver X receptor ligand, decreased nuclear PPARγ and cytosol IκB and increased nuclear NF-κB protein levels. We conclude that 25HC3S acts in macrophages as a PPARγ ligand and suppresses inflammatory responses via the PPARγ/IκB/NF-κB signaling pathway.

Inhibitory kappa B Kinases as targets for pharmacological regulation

The inhibitory kappa B kinases (IKKs) are well recognized as key regulators of the nuclear factor kappa B (NF-κB) cascade and as such represent a point of convergence for many extracellular agents that activate this pathway. The IKKs generally serve to transduce pro-inflammatory and growth stimulating signals that contribute to major cellular processes but also play a key role in the pathogenesis of a number of human diseases. Therefore, the catalytic IKKs represent attractive targets for intervention with small molecule kinase inhibitors. IKK isoforms are assembled as variable multi-subunit IKK complexes that regulate not only NF-κB dimers, but also protein substrates out-with this cascade. Consequently, close consideration of how these individual complexes transduce extracellular signals and more importantly what impact small molecule inhibitors of the IKKs have on functional outcomes are demanded. A number of adenosine triphosphate (ATP)-competitive IKKβ-selective inhibitors have been developed but have demonstrated a lack of activity against IKKα. A number of these chemicals have also exhibited detrimental outcomes such as cellular toxicity and immuno-suppression. The impact of small molecule inhibitors of IKK catalytic activity will therefore be reappraised, examining the advantages and potential disadvantages to this type of intervention strategy in the treatment of diseases such as arthritis, intestinal inflammation and cancer. Furthermore, we will outline some emerging strategies, particularly the disruption of protein-protein interactions within the IKK complex, as an alternative route towards the development of novel pharmacological agents. Whether these alternatives may negate the limitations of ATP-competitive molecules and potentially avoid the issues of toxicity will be discussed.

Monoclonal antibodies for the treatment of asthma

Asthma is a chronic inflammatory disease of the airways which can have a detrimental effect on quality of life and in extreme cases cause death. Although the majority of patients can control their asthma symptoms with a combination of steroids and beta agonists there is still a group of patients whose asthma remains symptomatic despite the best available treatment. These severe asthmatic patients represent the unmet medical need in asthma and are the focus of those developing novel monoclonal antibody based drugs. The complex networks of cytokines and cells involved in the pathology of asthma provide plenty of scope for intervention with monoclonal antibody based drugs which are able to block cytokine or chemokine receptor interactions, deplete cells expressing a specific receptor or block cell/cell interactions. At present anti-IgE (Xolair©) is the only monoclonal antibody based drug approved for the treatment of asthma. However, a number of other antibody based drugs have been clinically tested in asthma including anti-IL-5, anti-IL-4, anti-IL-13, anti-TNFα, anti-CCR3, anti-CCR4 and anti-OX40L. This review will examine the development of these monoclonal antibody based therapies. Since many of these therapies have targeted key pathways in asthma pathology these studies provide information on patient stratification and asthma pathology.

Novel IkB kinase inhibitors for treatment of nuclear factor-kB-related diseases

INTRODUCTION

NF-kB is a key regulator of inflammation and immunity in cancer development. The IkB kinase (IKK) is a multisubunit complex containing catalytic subunits termed IKK-α, -β and -γ. It is well known that many pro-inflammatory stimuli require the IKK-β subunit for NF-kB activation.

AREAS COVERED

NF-kB affects the progression of inflammation-related diseases,such as myocardial ischemia, bronchial asthma, arthritis, cancer and other diseases. We review the characteristics and effects of these inhibitors on inflammatory and other diseases.

EXPERT OPINION

Various synthesized IKK inhibitors have been developed and they will be used clinically in the near future.

Lung-targeted overexpression of the NF-κB member RelB inhibits cigarette smoke-induced inflammation

Acute lung inflammation can be caused by a variety of respirable agents, including cigarette smoke. Long-term cigarette smoke exposure can cause chronic obstructive pulmonary disease (COPD), a serious illness that affects >10 million Americans. Cigarette smoke is a known inducer of inflammation and is responsible for approximately 90% of all COPD cases. RelB, a member of the NF-κB family, attenuates cigarette smoke-induced inflammatory mediator production in mouse lung fibroblasts in vitro. We hypothesized that overexpression of RelB in the airways of mice would dampen acute smoke-induced pulmonary inflammation. Mice received a recombinant adenovirus encoding RelB by intranasal aspiration to induce transient RelB overexpression in the lungs and were subsequently exposed to mainstream cigarette smoke. Markers of inflammation were analyzed after smoke exposure. Neutrophil infiltration, normally increased by smoke exposure, was significantly and potently decreased after RelB overexpression. Cigarette smoke-induced proinflammatory cytokine and chemokine production, cyclooxygenase-2 expression, and prostaglandin E(2) production were also significantly decreased in the context of RelB overexpression. The expression of intercellular adhesion molecule 1, an NF-κB-dependent protein, was decreased, indicating a potential mechanism through which RelB can regulate inflammatory cell migration. Therefore, increased expression and/or activation of RelB could be a novel therapeutic strategy against acute lung inflammation caused by respirable agents and possibly against chronic injury, such as COPD.

Essential role of NF-κB and AP-1 transcription factors in TNF-α-induced TSLP expression in human airway smooth muscle cells

Human airway smooth muscle (HASM) cells are a rich source of inflammatory mediators that may propagate the airway inflammatory responses. Recent studies from our laboratory and others demonstrate that HASM cells express the proallergic cytokine thymic stromal lymphopoietin (TSLP) in vitro and in vivo. Compelling evidence from in vitro studies and animal models suggest that the TSLP is a critical factor sufficient and necessary to induce or maintain the allergic airway inflammation. Despite of an immense interest in pathophysiology of TSLP in allergic inflammation, the triggers and mechanisms of TSLP expression remain inadequately understood. In this study, we found that TNF-α upregulates the TSLP mRNA and induces high levels of TSLP protein release in primary human ASM cells. Interestingly, TNF-α induced the TSLP promoter activity ( P < 0.05; n = 4) in HASM that was mediated by upstream NF-κB and activator protein-1 (AP-1) binding sites. Mutation in NF-κB and AP-1 binding sites completely abrogated the effect of TNF-α-mediated TSLP promoter activity and so did the expression of a dominant-negative mutant construct of IκB kinase. Furthermore, the peptide inhibitors of IκB kinase or NF-κB inhibited the TNF-α-induced TSLP protein release ( P < 0.05; n = 3) in HASM. Collectively, our data suggest a novel important biological role for NF-κB pathway in TNF-α-induced TSLP expression in HASM and recommend this as a prime target for anti-inflammatory drugs.

Animal products, diseases and drugs: a plea for better integration between agricultural sciences, human nutrition and human pharmacology

Eicosanoids are major players in the pathogenesis of several common diseases, with either overproduction or imbalance (e.g. between thromboxanes and prostacyclins) often leading to worsening of disease symptoms. Both the total rate of eicosanoid production and the balance between eicosanoids with opposite effects are strongly dependent on dietary factors, such as the daily intakes of various eicosanoid precursor fatty acids, and also on the intakes of several antioxidant nutrients including selenium and sulphur amino acids. Even though the underlying biochemical mechanisms have been thoroughly studied for more than 30 years, neither the agricultural sector nor medical practitioners have shown much interest in making practical use of the abundant high-quality research data now available. In this article, we discuss some specific examples of the interactions between diet and drugs in the pathogenesis and therapy of various common diseases. We also discuss, using common pain conditions and cancer as specific examples, how a better integration between agricultural science, nutrition and pharmacology could lead to improved treatment for important diseases (with improved overall therapeutic effect at the same time as negative side effects and therapy costs can be strongly reduced). It is shown how an unnaturally high omega-6/omega-3 fatty acid concentration ratio in meat, offal and eggs (because the omega-6/omega-3 ratio of the animal diet is unnaturally high) directly leads to exacerbation of pain conditions, cardiovascular disease and probably most cancers. It should be technologically easy and fairly inexpensive to produce poultry and pork meat with much more long-chain omega-3 fatty acids and less arachidonic acid than now, at the same time as they could also have a similar selenium concentration as is common in marine fish. The health economic benefits of such products for society as a whole must be expected vastly to outweigh the direct costs for the farming sector.

TGF-β regulates Nox4, MnSOD and catalase expression, and IL-6 release in airway smooth muscle cells

Reactive oxygen species (ROS) are generated as a result of normal cellular metabolism, mainly through the mitochondria and peroxisomes, but their release is enhanced by the activation of oxidant enzymes such as NADPH oxidases or downregulation of endogenous antioxidant enzymes such as manganese-superoxide dismutase (MnSOD) and catalase. Transforming growth factor-β (TGF-β), found to be overexpressed in airway smooth muscle (ASM) from asthmatic and chronic obstructive pulmonary disease patients, may be a pivotal regulator of abnormal ASM cell (ASMC) function in these diseases. An important effect of TGF-β on ASMC inflammatory responses is the induction of IL-6 release. TGF-β also triggers intracellular ROS release in ASMCs by upregulation of NADPH oxidase 4 (Nox4). However, the effect of TGF-β on the expression of key antioxidant enzymes and subsequently on oxidant/antioxidant balance is unknown. Moreover, the role of redox-dependent pathways in the mediation of the proinflammatory effects of TGF-β in ASMCs is unclear. In this study, we show that TGF-β induced the expression of Nox4 while at the same time inhibiting the expression of MnSOD and catalase. This change in oxidant/antioxidant enzymes was accompanied by elevated ROS levels and IL-6 release. Further studies revealed a role for Smad3 and phosphatidyl-inositol kinase-mediated pathways in the induction of oxidant/antioxidant imbalance and IL-6 release. The changes in oxidant/antioxidant enzymes and IL-6 release were reversed by the antioxidants N-acetyl-cysteine (NAC) and ebselen through inhibition of Smad3 phosphorylation, indicating redox-dependent activation of Smad3 by TGF-β. Moreover, these findings suggest a potential role for NAC in preventing TGF-β-mediated pro-oxidant and proinflammatory responses in ASMCs. Knockdown of Nox4 using small interfering RNA partially prevented the inhibition of MnSOD but had no effect on catalase and IL-6 expression. These findings provide novel insights into redox regulation of ASM function by TGF-β.

Extracellular acidification stimulates IL-6 production and Ca(2+) mobilization through proton-sensing OGR1 receptors in human airway smooth muscle cells

The asthmatic airway has been shown to be an acidic environment that may be involved in the pathophysiological features of asthma. However, the mechanism by which an acidic pH modulates the cellular activities involved in the asthmatic airway remains elusive. Here, we characterized acidic pH-induced actions in human airway smooth muscle cells (ASMCs). Extracellular acidification stimulates the mRNA expression and protein production of IL-6, a proinflammatory cytokine, in association with the phosphorylation of extracellular signal-regulated kinase (ERK) and p38MAPK, reflecting the activation of the enzymes. Acidification-induced cytokine production was inhibited by inhibitors of ERK and p38MAPK. Acidification also increased intracellular Ca(2+) concentration, which was accompanied by cell rounding, most likely reflecting contraction. In ASMCs, OGR1 is expressed at by far the highest levels among proton-sensing G protein-coupled receptors. The knockdown of OGR1 and G(q/11) protein with their specific small interfering RNAs and an inhibition of G(q/11) protein with YM-254890 attenuated the acidification-induced actions. We conclude that extracellular acidification stimulates IL-6 production and Ca(2+) mobilization through proton-sensing OGR1 receptors/G(q/11) proteins in human ASMCs.

CaM kinase II in colonic smooth muscle contributes to dysmotility in murine DSS-colitis

BACKGROUND

Altered calcium mobilization has been implicated in the development of colonic dysmotility in inflammatory bowel disease. The aim of this study was to investigate the mechanisms by which disrupted intracellular Ca(2+) signalling contributes to the impaired contractility of colon circular smooth muscles.

METHODS

Acute colitis was induced in C57Bl/6 mice with dextran sulphate sodium (DSS) in the drinking water for 5 days.

KEY RESULTS

Spontaneous and acetylcholine-evoked contractions, caffeine-evoked hyperpolarization, and SERCA2 and phospholamban expression were reduced compared with controls. Tetrodotoxin did not restore control levels of contractile activity. The amplitudes, but not the frequency, of intracellular Ca(2+) waves were increased compared with controls. Caffeine abolished intracellular Ca(2+) waves in control smooth muscle cells, but not in smooth muscle cells from DSS-treated mice. CaM kinase II activity and cytosolic levels of HDAC4 were increased, and I kappaB alpha levels were decreased in distal colon smooth muscles from DSS-treated mice.

CONCLUSIONS & INFERENCES

These results suggest that disruptions in intracellular Ca(2+) mobilization due to down-regulation of SERCA2 and phospholamban expression lead to increased CaM kinase II activity and cytosolic HDAC4 that may contribute to the dysmotility of colonic smooth muscles in colitis by enhancing NF-kappaB activity.

FGF-16 is a target for adrenergic stimulation through NF-kappaB activation in postnatal cardiac cells and adult mouse heart

AIMS

The fibroblast growth factor (FGF) family plays an important role in cardiac growth and development. However, only FGF-16 RNA levels are reported to increase during the perinatal period and to be expressed preferentially in the myocardium, suggesting control at the transcriptional level and a role for FGF-16 in the postnatal heart. Beyond the identification of two TATA-like elements (TATA1 and TATA2) in the mouse FGF-16 promoter region and the preferential cardiac activity of TATA2, there is no report of Fgf-16 gene regulation. Assessment of promoter sequences, however, reveals putative nuclear factor-kappaB (NF-kappaB) elements, suggesting that Fgf-16 is regulated via NF-kappaB activation and thereby implicated in a number of cardiac events. Thus, the Fgf-16 gene was investigated as a target for NF-kappaB activation in cardiac cells.

METHODS AND RESULTS

Assessments of Fgf-16 promoter activity were made using truncated and transfected hybrid genes with NF-kappaB inhibitors and/or beta-adrenergic stimulation via isoproterenol (IsP) treatment (a known NF-kappaB activator) in culture, and on endogenous mouse and human Fgf-16 genes in situ. The mouse Fgf-16 promoter region was stimulated in response to IsP treatment, but this response was lost with NF-kappaB inhibitor pretreatment. Deletion analysis revealed IsP responsiveness linked to sequences between TATA2 and TATA1 and, more specifically, a NF-kappaB element upstream and adjacent to TATA1 that associates with NF-kappaB p50/p65 subunits in chromatin. Finally, TATA1 and the proximal NF-kappaB element are conserved in the human genome and responsive to IsP.

CONCLUSION

The mouse and human Fgf-16 gene is a target for NF-kappaB activation in the postnatal heart.

Pharmacological strategies for improving the efficacy and therapeutic ratio of glucocorticoids in inflammatory lung diseases

Glucocorticoids are widely used to treat various inflammatory lung diseases. Acting via the glucocorticoid receptor (GR), they exert clinical effects predominantly by modulating gene transcription. This may be to either induce (transactivate) or repress (transrepress) gene transcription. However, certain individuals, including those who smoke, have certain asthma phenotypes, chronic obstructive pulmonary disease (COPD) or some interstitial diseases may respond poorly to the beneficial effects of glucocorticoids. In these cases, high dose, often oral or parental, glucocorticoids are typically prescribed. This generally leads to adverse effects that compromise clinical utility. There is, therefore, a need to enhance the clinical efficacy of glucocorticoids while minimizing adverse effects. In this context, a long-acting beta(2)-adrenoceptor agonist (LABA) can enhance the clinical efficacy of an inhaled corticosteroid (ICS) in asthma and COPD. Furthermore, LABAs can augment glucocorticoid-dependent gene expression and this action may account for some of the benefits of LABA/ICS combination therapies when compared to ICS given as a monotherapy. In addition to metabolic genes and other adverse effects that are induced by glucocorticoids, there are many other glucocorticoid-inducible genes that have significant anti-inflammatory potential. We therefore advocate a move away from the search for ligands of GR that dissociate transactivation from transrepression. Instead, we submit that ligands should be functionally screened by virtue of their ability to induce or repress biologically-relevant genes in target tissues. In this review, we discuss pharmacological methods by which selective GR modulators and "add-on" therapies may be exploited to improve the clinical efficacy of glucocorticoids while reducing potential adverse effects.

Gene therapy targeting nuclear factor-kappaB: towards clinical application in inflammatory diseases and cancer

Nuclear factor (NF)-κB is regarded as one of the most important transcription factors and plays an essential role in the transcriptional activation of pro-inflammatory cytokines, cell proliferation and survival. NF-κB can be activated via two distinct NF-κB signal transduction pathways, the so-called canonical and non-canonical pathways, and has been demonstrated to play a key role in a wide range of inflammatory diseases and various types of cancer. Much effort has been put in strategies to inhibit NF-κB activation, for example by the development of pharmacological compounds that selectively inhibit NF-κB activity and therefore would be beneficial for immunotherapy of transplantation, autoimmune and allergic diseases, as well as an adjuvant approach in patients treated with chemotherapy for cancer. Gene therapy targeting NF-κB is a promising new strategy with the potential of long-term effects and has been explored in a wide variety of diseases, ranging from cancer to transplantation medicine and autoimmune diseases. In this review we discuss recent progress made in the development of NF-κB targeted gene therapy and the evolution towards clinical application.

Divergent intracellular pathways regulate interleukin-1beta-induced miR-146a and miR-146b expression and chemokine release in human alveolar epithelial cells

We have previously reported that IL-beta-induced miR-146a and miR-146b expression negatively regulates IL-8 and RANTES release in human alveolar A549 epithelial cells. To determine the intracellular pathways that regulate this response, we demonstrate IL-1beta-induced activation of the nuclear factor (NF)-kappaB, extracellular regulated kinase (ERK)-1/2, c-jun N-terminal kinase (JNK)-1/2 and p38 mitogen activated kinase (MAP) kinase pathways. Subsequent pharmacological studies show that IL-1beta-induced miR-146a, IL-8 and RANTES production was regulated via NF-kappaB and JNK-1/2 whilst miR-146b expression was mediated via MEK-1/2 and JNK-1/2. These divergent intracellular pathways likely explain the differential expression and biological action of the miR-146 isoforms.

Novel tight-binding inhibitory factor-kappaB kinase (IKK-2) inhibitors demonstrate target-specific anti-inflammatory activities in cellular assays and following oral and local delivery in an in vivo model of airway inflammation

Nuclear factor-kappaB (NF-kappaB) is one of the major families of transcription factors activated during the inflammatory response in asthma and chronic obstructive pulmonary disease. Inhibitory factor-kappaB kinase 2 (IKK-2) has been shown to play a pivotal role in cytokine-induced NF-kappaB activation in airway epithelium and in disease-relevant cells. Nevertheless, the potential toxicity of specific IKK-2 inhibitors may be unacceptable for oral delivery in chronic obstructive pulmonary disease. Therefore, local delivery to the lungs is an attractive alternative that warrants further exploration. Here, we describe potent and selective small-molecule IKK-2 inhibitors [8-(5-chloro-2-(4-methylpiperazin-1-yl)isonicotinamido)-1-(4-fluorophenyl)-4,5-dihydro-1H-benzo[g]indazole-3-carboxamide (PHA-408) and 8-(2-(3,4-bis(hydroxymethyl)-3,4-dimethylpyrrolidin-1-yl)-5-chloroisonicotinamido)-1-(4-fluorophenyl)-4,5-dihydro-1H-benzo-[g]indazole-3-carboxamide (PF-184)] that are competitive for ATP have slow off-rates from IKK-2 and display broad in vitro anti-inflammatory activities resulting from NF-kappaB pathway inhibition. Notably, PF-184 has been designed to have high systemic clearance, which limits systemic exposure and maximizes the effects locally in the airways. We used an inhaled lipopolysaccharide-induced rat model of neutrophilia to address whether inhibiting NF-kappaB activation locally within the airways would show anti-inflammatory effects in the absence of systemic exposure. PHA-408, a low-clearance compound previously shown to be efficacious orally in a rodent model of arthritis, dose-dependently attenuated inhaled lipopolysaccharide-induced cell infiltration and cytokine production. Interestingly, PF-184 produced comparable dose-dependent anti-inflammatory activity by intratracheal administration and was as efficacious as intratracheally administered fluticasone propionate (fluticasone). Together, these results support the potential therapeutic utility of IKK-2 inhibition in inflammatory pulmonary diseases and demonstrate anti-inflammatory efficacy of an inhaled IKK-2 inhibitor in a rat airway model of neutrophilia.

Dimethylfumarate inhibits NF-{kappa}B function at multiple levels to limit airway smooth muscle cell cytokine secretion

The antipsoriatic dimethylfumarate (DMF) has been anecdotically reported to reduce asthma symptoms and to improve quality of life of asthma patients. DMF decreases the expression of proinflammatory mediators by inhibiting the transcription factor NF-kappaB and might therefore be of interest for the therapy of inflammatory lung diseases. In this study, we determined the effect of DMF on platelet-derived growth factor (PDGF)-BB- and TNFalpha-induced asthma-relevant cytokines and NF-kappaB activation by primary human asthmatic and nonasthmatic airway smooth muscle cells (ASMC). Confluent nonasthmatic and asthmatic ASMC were incubated with DMF (0.1-100 microM) and/or dexamethasone (0.0001-0.1 microM), NF-kappaB p65 siRNA (100 nM), the NF-kappaB inhibitor helenalin (1 microM) before stimulation with PDGF-BB or TNFalpha (10 ng/ml). Cytokine release was measured by ELISA. NF-kappaB, mitogen and stress-activated kinase (MSK-1), and CREB activation was determined by immunoblotting and EMSA. TNFalpha-induced eotaxin, RANTES, and IL-6 as well as PDGF-BB-induced IL-6 expression was inhibited by DMF and by dexamethasone from asthmatic and nonasthmatic ASMC, but the combination of both drugs showed no glucocorticoid sparing effect in either of the two groups. NF-kappaB p65 siRNA and/or the NF-kappaB inhibitor helenalin reduced PDGF-BB- and TNFalpha-induced cytokine expression, suggesting the involvement of NF-kappaB signaling. DMF inhibited TNFalpha-induced NF-kappaB p65 phosphorylation, NF-kappaB nuclear entry, and NF-kappaB-DNA complex formation, whereas PDGF-BB appeared not to activate NF-kappaB within 60 min. Both stimuli induced the phosphorylation of MSK-1, NF-kappaB p65 at Ser276, and CREB, and all were inhibited by DMF. These data suggest that DMF downregulates cytokine secretion not only by inhibiting NF-kappaB but a wider range of NF-kappaB-linked signaling proteins, which may explain its potential beneficial effect in asthma.

Transcriptional regulation of cytokine function in airway smooth muscle cells

The immuno-modulatory properties of airway smooth muscle have become of increasing importance in our understanding of the mechanisms underlying chronic inflammation and structural remodeling of the airway wall in asthma and chronic obstructive pulmonary disease (COPD). ASM cells respond to many cytokines, growth factors and lipid mediators to produce a wide array of immuno-modulatory molecules which may in turn orchestrate and perpetuate the disease process in asthma and COPD. Despite numerous studies of the cellular effects of cytokines on cultured ASM, few have identified intracellular signaling pathways by which cytokines modulate or induce these cellular responses. In this review we provide an overview of the transcriptional mechanisms as well as intracellular signaling pathways regulating cytokine functions in ASM cells. The recent discovery of toll-like receptors in ASM cells represents a significant development in our understanding of the immuno-modulatory capabilities of ASM cells. Thus, we also review emerging evidence of the inflammatory response to toll-like receptor activation in ASM cells.

New approaches to the treatment of inflammatory disease : focus on small-molecule inhibitors of signal transduction pathways

This 'state-of-the-art' review specifically focuses on alternative signalling pathways deeply involved in acute and chronic inflammatory responses initiated by various pathological stimuli. The accumulated scientific knowledge has already revealed key biological targets, such as COX-2, and related pro-inflammatory mediators (cytokines and chemokines, interleukins [ILs], tumour necrosis factor [TNF]-alpha, migration inhibition factor [MIF], interferon [IFN]-gamma and matrix metalloproteinases [MMPs]) implicated in uncontrolled, destructive inflammatory reaction. A number of physiologically active agents are currently approved for market or are under active investigation in different clinical trials. However, recent findings have exposed the fatal adverse effects directly associated with drug therapy based on COX-2 inhibition. Given these possible harmful outcomes, a range of novel therapeutically relevant biological targets that include nuclear transcription factor (NF-kappaB), p38 mitogen-activated protein kinases (MAPK) and Janus protein tyrosine kinases and signal transducers and activators of transcription (JAK/STAT) signalling pathways has received growing attention. Here we discuss recent progress in the identification and development of novel, clinically approved or evaluated small-molecule regulators of these signalling cascades as promising anti-inflammatory drugs.

Targeting the NF-kappaB pathway in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease are inflammatory lung disorders responsible for significant morbidity and mortality worldwide. While the importance of allergic responses in asthma is well known, respiratory viral and bacterial infections and pollutants especially cigarette smoke are important factors in the pathogenesis of both diseases. Corticosteroid treatment remains the first preference of treatment in either disease, however these therapies are not always completely effective, and are associated with side effects and steroid resistance. Due to such limitations, development of new treatments represents a major goal for both the pharmaceutical industry and academic researchers. There are now excellent reasons to promote NF-kappaB signalling intermediates and Rel family proteins as potential therapeutic targets for both asthma and chronic obstructive pulmonary disease. This notion is supported by the fact that much of the underlying inflammation of both diseases independent of stimuli, is mediated at least in part, by NF-kappaB mediated signalling events in several cell types. Also, a range of inhibitors of NF-kappaB signalling intermediates are now available, including DNA oligonucleotides and DNA-peptide molecules that act as NF-kappaB decoy sequences, small molecule inhibitors such as IKK-beta inhibitors, and proteasome inhibitors affecting NF-kappaB signalling, that have either shown promise in animal models or have begun clinical trials in other disorders. This review will focus on the role of NF-kappaB in both diseases, will discuss its suitability as a target, and will highlight recent key studies that support the potential of NF-kappaB as a therapeutic target in these two important inflammatory lung diseases.

Induction of angiogenesis by murine resistin: putative role of PI3-kinase and NO-dependent pathways

Adipose tissue is a highly active endocrine organ, secreting bioactive molecules, adipokines, into the circulation. Obesity results in dysregulated adipokine secretion, contributing to pathophysiologies associated with this disorder, including insulin resistance and cardiovascular disease.

OBJECTIVES

To establish whether resistin, a novel bioactive molecule produced by murine adipose tissue, and implicated in insulin resistance in rodents, can induce angiogenic responses in aortic tissues and endothelial cells in vitro, and to investigate the signal transduction pathways involved in these responses.

RESULTS

Recombinant murine resistin (5-100 ng ml(-1)) induced sprouting of cellular networks and migration from murine aortic arch explants, primary aortic endothelial cells and in a 'wound healing' model utilising murine b.End5 endothelioma cells. The increased migration and sprouting of endothelial cells, due to resistin, were blocked by wortmannin (100 nM) and LY294002 (10 microM), inhibitors of phosphatidylinositol-3-kinase (PI3K), and accompanied by PI3K-dependent phosphorylation of Akt; moreover, while the changes were not associated with altered production of nitric oxide (NO), resistin-induced angiogenic responses were inhibited by IKK Inhibitor X (5 microM), an inhibitor of activation of nuclear factor (NF)-kappaB.

CONCLUSIONS

Murine resistin induces endothelial cell migration and sprouting of cellular networks via a mechanism which appears dependent upon PI3K and NF-kappaB activity, but independent of altered NO production. Resistin may contribute to angiogenic responses sustaining adipose tissue expansion, or in arterial tissues distal to this site.

Estrogen receptor beta: expression profile and possible anti-inflammatory role in disease

Estrogen receptor (ER) beta agonists have been demonstrated to possess anti-inflammatory properties in inflammatory disease models. The objective of this study was to determine whether ERbeta agonists affect in vitro and in vivo preclinical models of asthma. mRNA expression assays were validated in human and rodent tissue panels. These assays were then used to measure expression in human cells and our characterized rat model of allergic asthma. ERB-041 [7-ethenyl-2-(3-fluoro-4-hydroxyphenyl)-1,3-benzoxazol-5-ol], an ERbeta agonist, was profiled on cytokine release from interleukin-1beta-stimulated human airway smooth muscle (HASM) cells and in the rodent asthma model. Although ERbeta expression was demonstrated at the gene and protein level in HASM cells, the agonist failed to have an impact on the inflammatory response. Similarly, in vivo, we observed temporal modulation of ERbeta expression after antigen challenge. However, the agonist failed to have an impact on the model endpoints such as airway inflammation, even though plasma levels reflected linear compound exposure and was associated with an increase in receptor activation after drug administration. In these modeling systems of airway inflammation, an ERbeta agonist was ineffective. Although ERbeta agonists are anti-inflammatory in certain models, this novel study would suggest that they would not be clinically useful in the treatment of asthma.

Effect of beta2-adrenoceptor agonists and other cAMP-elevating agents on inflammatory gene expression in human ASM cells: a role for protein kinase A

In diseases such as asthma, airway smooth muscle (ASM) cells play a synthetic role by secreting inflammatory mediators such as granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-6, or IL-8 and by expressing surface adhesion molecules, including ICAM-1. In the present study, PGE(2), forskolin, and short-acting (salbutamol) and long-acting (salmeterol and formoterol) beta(2)-adrenoceptor agonists reduced the expression of ICAM-1 and the release of GM-CSF evoked by IL-1beta in ASM cells. IL-1beta-induced IL-8 release was also repressed by PGE(2) and forskolin, whereas the beta(2)-adrenoceptor agonists were ineffective. In each case, repression of these inflammatory indexes was prevented by adenoviral overexpression of PKIalpha, a highly selective PKA inhibitor. These data indicate a PKA-dependent mechanism of repression and suggest that agents that elevate intracellular cAMP, and thereby activate PKA, may have a widespread anti-inflammatory effect in ASM cells. Since ICAM-1 and GM-CSF are highly NF-kappaB-dependent genes, we used an adenoviral-delivered NF-kappaB-dependent luciferase reporter to examine the effects of forskolin and the beta(2)-adrenoceptor agonists on NF-kappaB activation. There was no effect on luciferase activity measured in the presence of forskolin or beta(2)-adrenoceptor agonists. This finding is consistent with the observation that IL-1beta-induced expression of IL-6, a known NF-kappaB-dependent gene in ASM, was also unaffected by beta(2)-adrenoceptor agonists, forskolin, PGE(2), 8-bromo-cAMP, or rolipram. Collectively, these results indicate that repression of IL-1beta-induced ICAM-1 expression and GM-CSF release by cAMP-elevating agents, including beta(2)-adrenoceptor agonists, may not occur through a generic effect on NF-kappaB.

Corticosteroids reduce IL-6 in ASM cells via up-regulation of MKP-1

The mechanisms by which corticosteroids reduce airway inflammation are not completely understood. Traditionally, corticosteroids were thought to inhibit cytokines exclusively at the transcriptional level. Our recent evidence, obtained in airway smooth muscle (ASM), no longer supports this view. We have found that corticosteroids do not act at the transcriptional level to reduce TNF-alpha-induced IL-6 gene expression. Rather, corticosteroids inhibit TNF-alpha-induced IL-6 secretion by reducing the stability of the IL-6 mRNA transcript. TNF-alpha-induced IL-6 mRNA decays at a significantly faster rate in ASM cells pretreated with the corticosteroid dexamethasone (t(1/2) = 2.4 h), compared to vehicle (t(1/2) = 9.0 h; P < 0.05) (results are expressed as decay constants [k] [mean +/- SEM] and half-life [h]). Interestingly, the underlying mechanism of inhibition by corticosteroids is via the up-regulation of an endogenous mitogen-activated protein kinase (MAPK) inhibitor, MAPK phosphatase-1 (MKP-1). Corticosteroids rapidly up-regulate MKP-1 in a time-dependent manner (44.6 +/- 10.5-fold increase after 24 h treatment with dexamethasone; P < 0.05), and MKP-1 up-regulation was temporally related to the inhibition of TNF-alpha-induced p38 MAPK phosphorylation. Moreover, TNF-alpha acts via a p38 MAPK-dependent pathway to stabilize the IL-6 mRNA transcript (TNF-alpha, t(1/2) = 9.6 h; SB203580 + TNF-alpha, t(1/2) = 1.5 h), exogenous expression of MKP-1 significantly inhibits TNF-alpha-induced IL-6 secretion and MKP-1 siRNA reverses the inhibition of TNF-alpha-induced IL-6 secretion by dexamethasone. Taken together, these results suggest that corticosteroid-induced MKP-1 contributes to the repression of IL-6 secretion in ASM cells.

A novel inflammatory pathway involved in leukocyte recruitment: role for the kinin B1 receptor and the chemokine CXCL5

The kinin B1 receptor is an inducible receptor not normally expressed but induced by inflammatory stimuli and plays a major role in neutrophil recruitment, particularly in response to the cytokine IL-1beta. However, the exact mechanism involved in this response is unclear. The aim of this study was to dissect the molecular mechanism involved, in particular to determine whether specific ELR-CXCL chemokines (specific neutrophil chemoattractants) played a role. Using intravital microscopy, we demonstrated that IL-1beta-induced leukocyte rolling, adherence, and emigration in mesenteric venules of wild-type (WT) mice, associated with an increase in B1 receptor mRNA expression, were substantially attenuated (>80%) in B1 receptor knockout mice (B1KO). This effect in B1KO mice was correlated with a selective down-regulation of IL-1beta-induced CXCL5 mRNA and protein expression compared with WT mice. Furthermore a selective neutralizing CXCL5 Ab caused profound suppression of leukocyte emigration in IL-1beta-treated WT mice. Finally, treatment of human endothelial cells with IL-1beta enhanced mRNA expression of the B1 receptor and the human (h) CXCL5 homologues (hCXCL5 and hCXCL6). This response was suppressed by approximately 50% when cells were pretreated with the B1 receptor antagonist des-Arg9-[Leu8]-bradykinin while treatment with des-Arg9-bradykinin, the B1 receptor agonist, caused a concentration-dependent increase in hCXCL5 and hCXCL6 mRNA expression. This study unveils a proinflammatory pathway centered on kinin B1 receptor activation of CXCL5 leading to leukocyte trafficking and highlights the B1 receptor as a potential target in the therapeutics of inflammatory disease.

Separating transrepression and transactivation: a distressing divorce for the glucocorticoid receptor?

Glucocorticoids (corticosteroids) are highly effective in combating inflammation in the context of a variety of diseases. However, clinical utility can be compromised by the development of side effects, many of which are attributed to the ability of the glucocorticoid receptor (GR) to induce the transcription of, or transactivate, certain genes. By contrast, the anti-inflammatory effects of glucocorticoids are due largely to their ability to reduce the expression of pro-inflammatory genes. This effect has been predominantly attributed to the repression of key inflammatory transcription factors, including AP-1 and NF-kappaB, and is termed transrepression. The ability to functionally separate these transcriptional functions of GR has prompted a search for dissociated GR ligands that can differentially induce transrepression but not transactivation. In this review, we present evidence that post-transcriptional mechanisms of action are highly important to the anti-inflammatory actions of glucocorticoids. Furthermore, we present the case that mechanistically distinct forms of glucocorticoid-inducible gene expression are critical to the development of anti-inflammatory effects by repressing inflammatory signaling pathways and inflammatory gene expression at multiple levels. Considerable care is therefore required to avoid loss of anti-inflammatory effectiveness in the development of novel transactivation-defective ligands of GR.

11th annual Inflammatory and Immune Diseases Drug Discovery and Development Summit 12-13 March 2007, San Francisco, USA

The Strategic Research Institute (SRi) hosted the 11th International Inflammation and Immune Diseases Drug Discovery and Development World Summit in San Francisco during 12-13 March 2007. The summit comprised keynote sessions and two parallel tracks and focussed on targeting mechanisms for drug discovery and development, which modulate the immune response and which have anti-inflammatory activity in a number of human diseases. Indications included psoriasis, hepatitis C, allergic dermatitis, systemic lupus erythematosus, rheumatoid arthritis and osteoarthritis, multiple sclnerosis, cardiovascular disease and asthma. Data were presented supporting all stages of drug discovery from target identification and validation through to lead identification and optimisation to both early- and late-stage clinical development.

Mechanisms of induction of airway smooth muscle hyperplasia by transforming growth factor-beta

Airway smooth muscle (ASM) hyperplasia is a characteristic feature of the asthmatic airway, but the underlying mechanisms that induce ASM hyperplasia remain unknown. Because transforming growth factor (TGF)-beta is a potent regulator of ASM cell proliferation, we determined its expression and mitogenic signaling pathways in ASM cells. We obtained ASM cells by laser capture microdissection of bronchial biopsies and found that ASM cells from asthmatic patients expressed TGF-beta1 mRNA and protein to a greater extent than nonasthmatic individuals using real-time RT-PCR and immunohistochemistry, respectively. TGF-beta1 stimulated the growth of nonconfluent and confluent ASM cells either in the presence or absence of serum in a time- and concentration-dependent manner. The mitogenic activity of TGF-beta1 on ASM cells was inhibited by selective inhibitors of TGF-beta receptor I kinase (SD-208), phosphatidylinositol 3-kinase (PI3K, LY-294002), ERK (PD-98059), JNK (SP-600125), and NF-kappaB (AS-602868). On the other hand, p38 MAPK inhibitor (SB-203580) augmented TGF-beta1-induced proliferation. To study role of the Smads, we transduced ASM cells with an adenovirus vector-expressing Smad4, Smad7, or dominant-negative Smad3 and found no involvement of these Smads in TGF-beta1-induced proliferation. Dexamethasone caused a dose-dependent inhibition in TGF-beta1-induced proliferation. Our findings suggest that TGF-beta1 may act in an autocrine fashion to induce ASM hyperplasia, mediated by its receptor and several kinases including PI3K, ERK, and JNK, whereas p38 MAPK is a negative regulator. NF-kappaB is also involved in the TGF-beta1 mitogenic signaling, but Smad pathway does not appear important.