Generation and characterization of a high affinity anti-human FcRn antibody, rozanolixizumab, and the effects of different molecular formats on the reduction of plasma IgG concentration

Rozanolixizumab (UCB7665), a humanized high-affinity anti-human neonatal Fc receptor (FcRn) monoclonal antibody (IgG4P), has been developed to reduce pathogenic IgG in autoimmune and alloimmune diseases. We document the antibody isolation and compare rozanolixizumab with the same variable region expressed in various mono-, bi- and trivalent formats. We report activity data for rozanolixizumab and the different molecular formats in human cells, FcRn-transgenic mice, and cynomolgus monkeys. Rozanolixizumab, considered the most effective molecular format, dose-dependently and selectively reduced plasma IgG concentrations in an FcRn-transgenic mouse model (no effect on albumin). Intravenous (IV) rozanolixizumab dosing in cynomolgus monkeys demonstrated non-linear pharmacokinetics indicative of target-mediated drug disposition; single IV rozanolixizumab doses (30 mg/kg) in cynomolgus monkeys reduced plasma IgG concentration by 69% by Day 7 post-administration. Daily IV administration of rozanolixizumab (initial 30 mg/kg loading dose; 5 mg/kg daily thereafter) reduced plasma IgG concentrations in all cynomolgus monkeys, with low concentrations maintained throughout the treatment period (42 days). In a 13-week toxicology study in cynomolgus monkeys, supra-pharmacological subcutaneous and IV doses of rozanolixizumab (≤ 150 mg/kg every 3 days) were well tolerated, inducing sustained (but reversible) reductions in IgG concentrations by up to 85%, with no adverse events observed. We have demonstrated accelerated natural catabolism of IgG through inhibition of IgG:FcRn interactions in mice and cynomolgus monkeys. Inhibition of FcRn with rozanolixizumab may provide a novel therapeutic approach to reduce pathogenic IgG in human autoimmune disease. Rozanolixizumab is being investigated in patients with immune thrombocytopenia (NCT02718716) and myasthenia gravis (NCT03052751).

Patient stratification and the unmet need in asthma

Asthma is often described as an inflammatory disease of the lungs and in most patients symptomatic treatment with bronchodilators or inhaled corticosteroids is sufficient to control disease. Unfortunately there are a proportion of patients who fail to achieve control despite treatment with the best current treatment. These severe asthma patients have been considered a homogeneous group of patients that represent the unmet therapeutic need in asthma. Many novel therapies have been tested in unselected asthma patients and the effects have often been disappointing, particularly for the highly specific monoclonal antibody-based drugs such as anti-IL-13 and anti-IL-5. More recently, it has become clear that asthma is a syndrome with many different disease drivers. Clinical trials of anti-IL-13 and anti-IL-5 have focused on biomarker-defined patient groups and these trials have driven the clinical progression of these drugs. Work on asthma phenotyping indicates that there is a group of asthma patients where T helper cell type 2 (Th2) cytokines and inflammation predominate and these type 2 high (T2-high) patients can be defined by biomarkers and response to therapies targeting this type of immunity, including anti-IL-5 and anti-IL-13. However, there is still a subset of T2-low patients that do not respond to these new therapies. This T2-low group will represent the new unmet medical need now that the T2-high-targeting therapies have made it to the market. This review will examine the current thinking on patient stratification in asthma and the identification of the T2-high subset. It will also look at the T2-low patients and examine what may be the drivers of disease in these patients.

OX40 blockade inhibits house dust mite driven allergic lung inflammation in mice and in vitro allergic responses in humans

The costimulatory receptor OX40 is expressed on activated T cells and regulates T-cell responses. Here, we show the efficacy and mechanism of action of an OX40 blocking antibody using the chronic house dust mite (HDM) mouse model of lung inflammation and in vitro HDM stimulation of cells from HDM allergic human donors. We have demonstrated that OX40 blockade leads to a reduction in the number of eosinophils and neutrophils in the lavage fluid and lung tissue of HDM sensitized mice. This was accompanied by a decrease in activated and memory CD4(+) T cells in the lungs and further analysis revealed that both the Th2 and Th17 populations were inhibited. Improved lung function and decreased HDM-specific antibody responses were also noted. Significantly, efficacy was observed even when anti-OX40 treatment was delayed until after inflammation was established. OX40 blockade also inhibited the release of the Th2 cytokines IL-5 and IL-13 from cells isolated from HDM allergic human donors. Altogether, our data provide evidence of a role of the OX40/OX40L pathway in ongoing allergic lung inflammation and support clinical studies of a blocking OX40 antibody in Th2 high severe asthma patients.

Cigarette smoke induced airway inflammation is independent of NF-κB signalling

RATIONALE

COPD is an inflammatory lung disease largely associated with exposure to cigarette smoke (CS). The mechanism by which CS leads to the pathogenesis of COPD is currently unclear; it is known however that many of the inflammatory mediators present in the COPD lung can be produced via the actions of the transcription factor Nuclear Factor-kappaB (NF-κB) and its upstream signalling kinase, Inhibitor of κB kinase-2 (IKK-2). Therefore the NF-κB/IKK-2 signalling pathway may represent a therapeutic target to attenuate the inflammation associated with COPD.

AIM

To use a range of assays, genetically modified animals and pharmacological tools to determine the role of NF-κB in CS-induced airway inflammation.

METHODS

NF-κB pathway activation was measured in pre-clinical models of CS-induced airway inflammation and in human lung tissue from COPD patients. This data was complemented by employing mice missing a functional NF-κB pathway in specific cell types (epithelial and myeloid cells) and with systemic inhibitors of IKK-2.

RESULTS

We showed in an airway inflammation model known to be NF-κB-dependent that the NF-κB pathway activity assays and modulators were functional in the mouse lung. Then, using the same methods, we demonstrated that the NF-κB pathway appears not to play an important role in the inflammation observed after exposure to CS. Furthermore, assaying human lung tissue revealed that in the clinical samples there was also no increase in NF-κB pathway activation in the COPD lung, suggesting that our pre-clinical data is translational to human disease.

CONCLUSIONS

In this study we present compelling evidence that the IKK-2/NF-κB signalling pathway does not play a prominent role in the inflammatory response to CS exposure and that this pathway may not be important in COPD pathogenesis.

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.

P2X7 receptor and caspase 1 activation are central to airway inflammation observed after exposure to tobacco smoke

Chronic Obstructive Pulmonary Disease (COPD) is a cigarette smoke (CS)-driven inflammatory airway disease with an increasing global prevalence. Currently there is no effective medication to stop the relentless progression of this disease. It has recently been shown that an activator of the P2X7/inflammasome pathway, ATP, and the resultant products (IL-1β/IL-18) are increased in COPD patients. The aim of this study was to determine whether activation of the P2X7/caspase 1 pathway has a functional role in CS-induced airway inflammation. Mice were exposed to CS twice a day to induce COPD-like inflammation and the role of the P2X7 receptor was investigated. We have demonstrated that CS-induced neutrophilia in a pre-clinical model is temporally associated with markers of inflammasome activation, (increased caspase 1 activity and release of IL-1β/IL-18) in the lungs. A selective P2X7 receptor antagonist and mice genetically modified so that the P2X7 receptors were non-functional attenuated caspase 1 activation, IL-1β release and airway neutrophilia. Furthermore, we demonstrated that the role of this pathway was not restricted to early stages of disease development by showing increased caspase 1 activation in lungs from a more chronic exposure to CS and from patients with COPD. This translational data suggests the P2X7/Inflammasome pathway plays an ongoing role in disease pathogenesis. These results advocate the critical role of the P2X7/caspase 1 axis in CS-induced inflammation, highlighting this as a possible therapeutic target in combating COPD.

Asthma & COPD--IQPC's Second Conference

The International Quality & Productivity Center's (IQPC) Second Asthma & COPD conference, held in Philadelphia, included topics covering new therapeutic developments in the field of asthma and COPD. This conference report highlights selected presentations on mAb treatments for asthma, including targeting IL-5, IL-13, IL-9 and TNFa, CCR3 inhibitors, histamine H4 receptor inhibition, novel mouse models of COPD and inhaled antisense asthma therapies. Investigational drugs discussed include mepolizumab (GlaxoSmithKline plc), benralizumab (BioWa Inc/Kyowa Hakko Kirin Co Ltd/MedImmune LLC), AMG-317 (Amgen Inc/Takeda Bio Development Center Ltd), TPI-ASM-8 (Pharmaxis Ltd) and AIR-645 (Altair Therapeutics Inc).

Liver X receptor agonists increase airway reactivity in a model of asthma via increasing airway smooth muscle growth

The liver X receptors (LXRalpha/beta) are orphan nuclear receptors that are expressed in a large number of cell types and have been shown to have anti-inflammatory properties. Nuclear receptors have previously proved to be amenable targets for small molecular mass pharmacological agents in asthma, and so the effect of an LXR ligand was assessed in models of allergic airway inflammation. LXR agonist, GW 3965, was profiled in rat and mouse models of allergic asthma. In the Brown Norway rats, GW 3965 (3-30 mg/kg) was unable to reduce the bronchoalveolar lavage eosinophilia associated with this model and had no impact on inflammatory biomarkers (eotaxin and IL-1beta). The compound did significantly stimulate ABCA-1 (ATP-binding cassette A1) mRNA expression, indicating that there was adequate exposure/LXR activation. In the mouse model, the LXR ligand surprisingly increased airway reactivity, an effect that was apparent in both the Ag and nonchallenged groups. This increase was not associated with a change in lung tissue inflammation or number of mucus-containing cells. There was, however, a marked increase in airway smooth muscle thickness in both treated groups. We demonstrated an increase in contractile response to exogenous methacholine in isolated airways taken from LXR agonist-treated animals compared with the relevant control tissue. We corroborated these findings in a human system by demonstrating increased proliferation of cultured airway smooth muscle. This phenomenon, if evidenced in man, would indicate that LXR ligands may directly increase airway reactivity, which could be detrimental, especially in patients with existing respiratory disease and with already compromised lung function.

PMX464, a thiol-reactive quinol and putative thioredoxin inhibitor, inhibits NF-kappaB-dependent proinflammatory activation of alveolar epithelial cells

BACKGROUND AND PURPOSE

Subtle changes in the intracellular reduction-oxidation (redox) state can modulate nuclear factor-kappaB (NF-kappaB) activity. Thioredoxin-1 (Trx) is a small, ubiquitous, redox-active thiol (-SH) protein that, with thioredoxin reductase-1 (TrxR), modifies the redox status of NF-kappaB pathway components. PMX464 is a novel thiol-reactive quinol thought to inhibit the Trx/TrxR system. The aim of this work was to investigate whether PMX464 inhibited NF-kappaB-mediated proinflammatory activation of human type II alveolar epithelial cells (A549).

EXPERIMENTAL APPROACH

Intercellular adhesion molecule-1 (ICAM-1), granulocyte-macrophage colony-stimulating factor (GM-CSF) and CXCL8, NF-kappaB DNA binding, nuclear translocation of NF-kappaB p65 subunit, IkappaBalpha degradation, IkappaB phosphorylation and IkappaB kinase (IKK) activity were assessed in A549 cells stimulated with IL-1beta with or without PMX464 pretreatment. Effects of PMX464 on ICAM-1 expression in human lung microvascular endothelial cells (HLMVEC) were also investigated. For comparison, selected measurements (ICAM-1 and IkappaB-alpha phospho-IkappaB-alpha) were made on A549 cells after RNA interference-mediated silencing (siRNA) of Trx.

KEY RESULTS

PMX464 reduced ICAM-1, GM-CSF and CXCL8 expression in IL-1beta-stimulated A549 cells and ICAM-1 in HLMVEC. PMX464 inhibited IL-1beta-induced NF-kappaB DNA binding, nuclear translocation of NF-kappaB p65 subunit and factors involved in NF-kappaB activation; specifically, IkappaBalpha degradation, IkappaB phosphorylation and IkappaB kinase (IKK) activity in A549. By contrast, Trx siRNA did not alter ICAM-1 expression or IkappaBalpha degradation/phosphorylation in IL-1beta-stimulated A549 cells.

CONCLUSION AND IMPLICATIONS

PMX464 inhibits a proinflammatory response in A549 cells targeting the NFkappaB pathway above IKK. The lack of effect with Trx siRNA suggests that PMX464 acts on thiol proteins, in addition to Trx, to elicit anti-inflammatory responses in lung epithelial cells.

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.

Impact of tobacco-smoke on key signaling pathways in the innate immune response in lung macrophages

Many of the healthcare consequences of cigarette smoking could be due to its ability to compromise the immune system, and in respiratory diseases like chronic obstructive pulmonary disease (COPD), a constant low level of infection could be responsible for some of the symptoms/pathology. The aim was to assess the impact of cigarette smoke (CS) on the release of innate effector cytokines in THP-1 cells and human lung macrophages, and to determine the molecular mechanism behind the altered response. Cells were exposed to CS with and without endotoxin stimulus, cytokines, glutathione, mitogen-activated protein kinase (MAPK) phosphorylation, IkappaB kinase-2 (IKK-2) activity, nuclear factor kappa B (NF-kappaB), and activator protein-1 (AP-1) pathway activation was measured. Attempts were made to mimic or block the effect of CS by using nicotine, nitric oxide donors/inhibitors, prostanoid inhibitors, and anti-oxidants. Results showed that CS initially delayed the production of "innate" cytokines (e.g., IL-1beta and IL-6) and reduced glutathione levels. This was associated with a reduction in NF-kappaB pathway activation, which suggested a causative link. CS also increased the phosphorylation of MAPK's and the production of IL-8 but interestingly only in stimulated cells. Exogenous glutathione treatment reversed both these effects of CS, which suggests that this molecule may play a central role. In conclusion, this data provides a novel mechanistic explanation for why smokers have increased prevalence/severity of respiratory infections. In addition, the suppression of the innate response is accompanied by an increase in the neutrophil chemoattractant, IL-8, which may suggest a link to the pathogenesis of smoking-related inflammatory disease.

Novel role for the liver X nuclear receptor in the suppression of lung inflammatory responses

The liver X receptors (LXRalpha/beta) are part of the nuclear receptor family and are believed to regulate cholesterol and lipid homeostasis. It has also been suggested that LXR agonists possess anti-inflammatory properties. The aim of this work was to determine the effect of LXR agonists on the innate immune response in human primary lung macrophages and a pre-clinical rodent model of lung inflammation. Before profiling the impact of the agonist, we established that both the human macrophages and the rodent lungs expressed LXRalpha/beta. We then used two structurally distinct LXR agonists to demonstrate that activation of this transcription factor reduces cytokine production in THP-1 cells and lung macrophages. Then, using the expression profile of ATP binding cassettes A1 (ABCA-1; a gene directly linked to LXR activation) as a biomarker for lung exposure of the compound, we demonstrated an LXR-dependent reduction in lung neutrophilia rodents in vivo. This inhibition was not associated with a suppression of c-Fos/c-Jun mRNA expression or NF-kappaB/AP-1 DNA binding, suggesting that any anti-inflammatory activity of LXR agonists is not via inhibition of NF-kappaB/AP-1 transcriptional activity. These data do not completely rule out an impact of these agonists on these two prominent transcription factors. In summary, this study is the first to demonstrate anti-inflammatory actions of LXRs in the lung. Chronic innate inflammatory responses observed in some airway diseases is thought to be central to disease pathogenesis. Therefore, data suggest that LXR ligands have utility in the treatment of lung diseases that involves chronic inflammation mediated by macrophages and neutrophils.

Repression of inflammatory gene expression in human pulmonary epithelial cells by small-molecule IkappaB kinase inhibitors

The airway epithelium is critical in the pathogenesis of chronic inflammatory diseases, such as asthma and chronic obstructive pulmonary disease, and, by expressing numerous inflammatory genes, plays a prominent role in disease exacerbations. Since inflammatory gene expression often involves the transcription factor nuclear factor (NF)-kappaB, this signaling pathway represents a site for anti-inflammatory intervention. As the airway epithelium is targeted by inhaled therapeutic agents, for example corticosteroids, human A549 pulmonary cells and primary human bronchial epithelial (HBE) cells were selected to evaluate inhibitor of kappaB kinase (IKK) inhibitors. In A549 cells, interleukin (IL)-1beta and tumor necrosis factor (TNF) alpha increased phosphorylation of IkappaBalpha, and this was followed by loss of IkappaBalpha, induction of NF-kappaB DNA binding, and the induction of NF-kappaB-dependent transcription. These events were repressed by the IKK-selective inhibitors, PS-1145 [N-(6-chloro-9H-beta-carbolin-8-ly) nicotinamide] and ML120B [N-(6-chloro-7-methoxy-9H-beta-carbolin-8-yl)-2-methyl-nicotinamide]. Inhibition of NF-kappaB-dependent transcription was concentration-dependent and correlated with loss of intercellular adhesion molecule (ICAM)-1 expression. Similarly, IL-1beta- and TNFalpha-induced expression of IL-6, IL-8, granulocyte macrophage-colony-stimulating factor (GM-CSF), regulated and activation normal T cell expressed and secreted (RANTES), growth-related oncogene alpha, and monocyte chemotactic protein-1 (MCP-1) was also significantly repressed. Likewise, PS-1145 and ML120B profoundly reduced NF-kappaB-dependent transcription induced by IL-1beta and TNFalpha in primary HBE cells. Parallel effects on ICAM-1 expression and a significant repression of IL-8 release were observed. In contrast, the corticosteroid, dexamethasone, was without effect on NF-kappaB-dependent transcription or the expression of ICAM-1. The above data provide strong support for an anti-inflammatory effect of IKK2 inhibitors acting on the pulmonary epithelium and suggest that such compounds may prove beneficial in situations where traditional corticosteroid therapies prove inadequate.

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

Asthma and chronic obstructive pulmonary disease (COPD) are characterized by chronic airway inflammation. However, because patients with COPD and certain patients with asthma show little or no therapeutic benefit from existing corticosteroid therapies, there is an urgent need for novel anti-inflammatory strategies. The transcription factor nuclear factor-kappaB (NF-kappaB) is central to inflammation and is necessary for the expression of numerous inflammatory genes. Proinflammatory cytokines, including interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha, activate the IkappaB kinase complex (IKK) to promote the degradation of inhibitory IkappaB proteins and activate NF-kappaB. This pathway and, in particular, the main IkappaB kinase, IKK2, are now considered prime targets for novel anti-inflammatory drugs. Therefore, we have used adenoviral overexpression to demonstrate NF-kappaB and IKK2 dependence of key inflammatory genes, including intercellular adhesion molecule (ICAM)-1, cyclooxygenase-2, IL-6, IL-8, granulocyte macrophage-colony-stimulating factor (GM-CSF), regulated on activation normal T cell expressed and secreted (RANTES), monocyte chemotactic protein-1 (MCP-1), growth-regulated oncogene-alpha (GROalpha), neutrophil-activating protein-2 (NAP-2), and epithelial neutrophil activating peptide 78 (ENA-78) in primary human airways smooth muscle cells. Because this cell type is central to the pathogenesis of airway inflammatory diseases, these data predict a beneficial effect of IKK2 inhibition. These validated outputs were therefore used to evaluate the novel IKK inhibitors N-(6-chloro-9H-beta-carbolin-8-yl) nicotinamide (PS-1145) and N-(6-chloro-7-methoxy-9H-beta-carbolin-8-yl)-2-methyl-nicotinamide (ML120B) on IL-1beta and TNFalpha-induced expression, and this was compared with the corticosteroid dexamethasone. As observed above, ICAM-1, IL-6, IL-8, GM-CSF, RANTES, MCP-1, GROalpha, NAP-2, and ENA-78 expression was reduced by the IKK inhibitors. Furthermore, this inhibition was either as effective, or for ICAM-1, MCP-1, GROalpha, and NAP-2, more effective, than a maximally effective concentration of dexamethasone. We therefore suggest that IKK inhibitors may be of considerable benefit in inflammatory airways diseases, particularly in COPD or severe asthma, in which corticosteroids are ineffective.

IkappaB kinase-2-independent and -dependent inflammation in airway disease models: relevance of IKK-2 inhibition to the clinic

Nuclear factor kappaB (NF-kappaB) is a transcription factor believed to be central in the expression of numerous inflammatory genes and the pathogenesis of many respiratory diseases. We have previously demonstrated increased NF-kappaB pathway activation in a steroid-sensitive animal model of lipopolysaccharide (LPS)-driven airway inflammation. It is noteworthy that this phenomenon was not observed in a steroid-insensitive model of elastase-induced inflammation in the rat. The aim of this study was to gather further evidence to suggest that these similar profiles of neutrophilic inflammation can be NF-kappaB-dependent or -independent by determining the impact of an IkappaB kinase-2 (IKK-2) inhibitor, 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1). In the LPS model, TPCA-1 blocked the increase in NF-kappaB DNA binding, a marker of NF-kappaB pathway activation. This inhibition was associated with a reduction in inflammatory mediator release [tumor necrosis factor alpha (TNFalpha)/interleukin-1beta (IL-1beta)/matrix metalloproteinase-9 (MMP-9)] and lung inflammatory cell burden (neutrophilia/eosinophilia). These data were paralleled with a steroid and in human cell based assays. In the elastase-driven inflammation model, in which our group has previously failed to measure an increase in NF-kappaB DNA binding, neither TPCA-1 nor the steroid, affected mediator release (IL-1beta/MMP-9) or cellular burden (neutrophilia/lymphomononuclear cells). This is the first study to examine the effect of an IKK-2 inhibitor in well validated models that mimic aspects of the inflammatory lesion evident in diseases such as COPD. In conclusion, we have demonstrated that animal models with similar profiles of airway inflammation can be IKK-2 inhibitor/steroid-sensitive or -insensitive. If both profiles of inflammation exist in the clinic, then this finding is extremely exciting and may lead to greater understanding of disease pathology and the discovery of novel anti-inflammatory targets.

Second-generation inhibitors demonstrate the involvement of p38 mitogen-activated protein kinase in post-transcriptional modulation of inflammatory mediator production in human and rodent airways

The exact role of p38 mitogen-activated protein kinase (MAPK) in the expression of inflammatory cytokines is not clear; it may regulate transcriptionally, post-transcriptionally, translationally, or post-translationally. The involvement of one or more of these mechanisms has been suggested to depend on the particular cytokine, the cell type studied, and the specific stimulus used. Interpretation of some of the published data is further complicated by the use of inhibitors such as 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-1H-imidazole (SB 203580) used at single, high concentrations. The aim of this study was to determine the impact of two second-generation p38 MAPK inhibitors on the expression of a range of inflammatory cytokines at the gene and protein levels in human cultured cells. Similar assessment of the impact of these compounds on inflammatory cytokine expression in a preclinical in vivo model of airway inflammation was performed. The results in THP-1 cells and primary airway macrophages clearly show that protein expression is inhibited at much lower concentrations of inhibitor than are needed to impact on gene expression. In the rodent model, both compounds, at doses that cause maximal inhibition of cellular recruitment, inhibit tumor necrosis factor alpha (TNFalpha) protein production without impacting on nuclear factor kappaB pathway activation or TNFalpha gene expression. In summary, the data shown here demonstrate that, although at high compound concentrations there is some level of transcriptional regulation, the predominant role of p38 MAPK in cytokine production is at the translational level. These data question whether the effect of p38 inhibitors on gene transcription is related to their potential therapeutic role as anti-inflammatory compounds.

Validation of IKK beta as therapeutic target in airway inflammatory disease by adenoviral-mediated delivery of dominant-negative IKK beta to pulmonary epithelial cells

Asthma is an inflammatory disease of the lungs and the transcription factor NF-kappa B regulates the production of numerous inflammatory mediators that may have a role in the pathogenesis of asthma. Hence, the signalling pathways leading to NF-kappa B activation are considered prime targets for novel anti-inflammatory therapies. The prevention of NF-kappa B activity in mice, through the knockout of IKK beta or p65, causes fatal liver degeneration in utero making it difficult to determine the full implications of inhibiting NF-kappaB activity in tissues physiologically relevant to human diseases. This study used adenovirus delivery of a dominant inhibitor of NF-kappaB (I kappa B alpha delta N) and dominant-negative IKK alpha (IKK alpha(KM)) and IKK beta (IKK beta(KA)) to investigate the role of the individual IKKs in NF-kappa B activation and inflammatory gene transcription by human pulmonary A549 cells. Overexpression of IKK beta(KA) or I kappa B alpha delta N prevented NF-kappa B-dependent transcription and DNA binding. IKK beta(KA) also prevented I kappa B alpha kinase activity. Similarly, IKK beta(KA) and I kappa B alpha delta N overexpression also inhibited IL-1beta- and TNF alpha-dependent increases in ICAM-1, IL-8 and GM-CSF in addition to IL-1beta-mediated increases in cyclooxygenase-2 expression, whereas IKK alpha(KM) overexpression had little effect on these outputs. IKK beta(KA) also reduced cell viability and induced caspase-3 and PARP cleavage regardless of the stimuli, indicating the induction of apoptosis. This effect seemed to be directly related to IKK beta kinase activity since I kappa B alpha delta N only induced PARP cleavage in TNF alpha-treated cells. These results demonstrate that inhibition of IKK beta and NF-kappa B suppresses inflammatory mediator production and reduces A549 cell viability. Thus, novel therapies that target IKK beta could have potent anti-inflammatory effects and may be beneficial in the treatment of certain cancers.

Differential effects of RU486 reveal distinct mechanisms for glucocorticoid repression of prostaglandin E2 release

In A549 pulmonary cells, the dexamethasone- and budesonide-dependent repression of interleukin-1beta-induced prostaglandin E2 release was mimicked by the steroid antagonist, RU486. Conversely, whereas dexamethasone and budesonide were highly effective inhibitors of interleukin-1beta-induced cyclooxygenase (COX)/prostaglandin E synthase (PGES) activity and COX-2 expression, RU486 (<1 microm) was a poor inhibitor, but was able to efficiently antagonize the effects of dexamethasone and budesonide. In addition, both dexamethasone and RU486 repressed [3H]arachidonate release, which is consistent with an effect at the level of phospholipase A2 activity. By contrast, glucocorticoid response element-dependent transcription was unaffected by RU486 but induced by dexamethasone and budesonide, whilst dexamethasone- and budesonide-dependent repression of nuclear factor-kappaB-dependent transcription was maximally 30-40% and RU486 (<1 microm) was without significant effect. Thus, two pharmacologically distinct mechanisms of glucocorticoid-dependent repression of prostaglandin E2 release are revealed. First, glucocorticoid-dependent repression of arachidonic acid is mimicked by RU486 and, second, repression of COX/PGES is antagonized by RU486. Finally, whilst all compounds induced glucocorticoid receptor translocation, no role for glucocorticoid response element-dependent transcription is supported in these inhibitory processes and only a limited role for glucocorticoid-dependent inhibition of nuclear factor-kappaB in the repression of COX-2 is indicated.

ICAM-1 expression is highly NF-kappaB-dependent in A549 cells. No role for ERK and p38 MAPK

The transcription factor nuclear factor kappaB (NF-kappaB) is an activator of multiple cytokines, chemokines and adhesion molecules, which are important in inflammatory diseases such as asthma, and is consequently considered as an attractive therapeutic target. In the present study, a constitutively active dominant version of IkappaBalpha, IkappaBalphaDN, was introduced into A549 pulmonary cells by adenovirus-mediated delivery. The dominant IkappaB, but not a null viral vector, prevented the induction of NF-kappaB-dependent transcription by both tumor necrosis factor alpha (TNFalpha) and interleukin-1beta (IL-1beta). Similarly, both TNFalpha and IL-1beta strongly induced mRNA and protein expression of intercellular adhesion molecule (ICAM)-1 and in each case this was prevented by adenovirus expressing the dominant IkappaB, but not by the null virus, thereby establishing ICAM-1 as an NF-kappaB-dependent gene. Numerous studies have suggested key roles for the p38 and extracellular regulated kinase (ERK) mitogen-activated protein kinase (MAPK) cascades in the activation and transactivation of NF-kappaB. We show here that SB203580, a selective inhibitor of the p38 MAPK, and PD098059 and UO126, both selective inhibitors of the ERK MAPK cascade, have no effect on TNFalpha or IL-1beta-induced translocation and DNA binding of NF-kappaB. Furthermore, these inhibitors showed no pharmacologically relevant effect on NF-kappaB-dependent transcription nor was there any effect on expression of ICAM-1. Taken together these data highlight the potential use of inhibition of the NF-kappaB signalling pathway in pulmonary inflammatory diseases and suggest that inhibitors of the p38 and ERK MAPK pathways may be of lesser effect.

Identification in human airways smooth muscle cells of the prostanoid receptor and signalling pathway through which PGE2 inhibits the release of GM-CSF

1. The prostanoid receptor(s) on human airways smooth muscle (HASM) cells that mediates the inhibitory effect of PGE(2) on interleukin (IL)-1 beta-induced granulocyte/macrophage colony-stimulating factor (GM-CSF) release has been classified. 2. IL-1 beta evoked the release of GM-CSF from HASM cells, which was suppressed by PGE(2), 16,16-dimethyl PGE(2) (nonselective), misoprostol (EP(2)/EP(3)-selective), ONO-AE1-259 and butaprost (both EP(2)-selective) with pIC(50) values of 8.61, 7.13, 5.64, 8.79 and 5.43, respectively. EP-receptor agonists that have selectivity for the EP(1)-(17-phenyl-omega-trinor PGE(2)) and EP(3)-receptor (sulprostone) subtypes as well as cicaprost (IP-selective), PGD(2), PGF(2 alpha) and U-46619 (TP-selective) were poorly active or inactive at concentrations up to 10 microM. 3. AH 6809, a drug that can be used to selectively block EP(2)-receptors in HASM cells, antagonised the inhibitory effect of PGE(2), 16,16-dimethyl PGE(2) and ONO-AE1-259 with apparent pA(2) values of 5.85, 6.09 and 6.1 respectively. In contrast, the EP(4)-receptor antagonists, AH 23848B and L-161,982, failed to displace to the right the concentration-response curves that described the inhibition of GM-CSF release evoked by PGE(2) and ONO-AE1-259. 4. Inhibition of GM-CSF release by PGE(2) and 8-Br-cAMP was abolished in cells infected with an adenovirus vector encoding an inhibitor protein of cAMP-dependent protein kinase (PKA) but not by H-89, a purported small molecule inhibitor of PKA. 5. We conclude that prostanoid receptors of the EP(2)-subtype mediate the inhibitory effect of PGE(2) on GM-CSF release from HASM cells by recruiting a PKA-dependent pathway. In addition, the data illustrate that caution should be exercised when using H-89 in studies designed to assess the role of PKA in biological processes.

Inhibitors of protein kinase C (PKC) prevent activated transcription: role of events downstream of NF-kappaB DNA binding

In pulmonary A549 cells, the protein kinase C (PKC) inhibitor, Ro 31-8220, and the phosphotidylcholine-specific phospholipase C inhibitor, D609, prevent NF-kappaB-dependent transcription, yet NF-kappaB DNA binding is unaffected (Bergmann, M., Hart, L., Lindsay, M., Barnes, P. J., and Newton, R. (1998) J. Biol. Chem. 273, 6607-6610). We now show that this effect also occurs in BEAS-2B bronchial epithelial cells as well as with other PKC inhibitors (Gö 6976, GF109203X, and calphostin C) in A549 cells. Similarly, phorbol ester, a diacylglycerol mimetic, activates NF-kappaB-dependent transcription and potentiates tumor necrosis factor alpha (TNFalpha)-induced NF-kappaB-dependent transcription, yet unlike TNFalpha, poorly activates IkappaB kinase (IKK) activity, IkappaBalpha degradation, or NF-kappaB DNA binding in both A549 and BEAS-2B cells. As phorbol ester-induced NF-kappaB-dependent transcription was relatively insensitive to the proteasome inhibitor, MG-132, PKC may affect NF-kappaB-dependent transcription via mechanisms other than the core IKK-IkappaB pathway. This is supported by Gal4 one hybrid analysis of p65/RelA transactivation, which was potentiated by TNFalpha and phorbol ester and was inhibited by Ro 31-8220 and D609. Additionally, a number of PKC isoforms, particularly the novel isoform PKCepsilon, induced p65/RelA transactivation. Phosphorylation of p65/RelA and cAMP-responsive element-binding protein (CREB)-binding protein (CBP) was increased by TNFalpha treatment and, in the case of CBP, was prevented by Ro 31-8220 or D609. However, p65/RelA-CBP interactions were unaffected by either compound. As this effect was not limited to NF-kappaB, but was a more general feature of inducible gene transcription, we suggest PKC isoforms may provide a point of intervention in diseases such as inflammation, or cancer, where activated gene expression is prominent.

Adenovirus-mediated delivery and expression of a cAMP-dependent protein kinase inhibitor gene to BEAS-2B epithelial cells abolishes the anti-inflammatory effects of rolipram, salbutamol, and prostaglandin E2: a comparison with H-89

cAMP-elevating drugs are thought to mediate their biological effects by activating the cAMP/cAMP-dependent protein kinase (PKA) cascade. However, this hypothesis is difficult to confirm due to a lack of selective inhibitors. Here, we have probed the role of PKA in mediating inhibitory effects of several cAMP-elevating drugs in BEAS-2B epithelial cells using an adenovirus vector encoding a PKA inhibitor protein (PKIalpha) and have compared it to H-89, a commonly used small molecule PKA inhibitor. Initial studies established efficient gene transfer and confirmed functionality of PKIalpha 48 h after virus infection. All cAMP-elevating drugs tested promoted the phosphorylation of cAMP response element-binding protein (CREB), activated a cAMP response element (CRE)-driven luciferase reporter gene, and suppressed both granulocyte/macrophage colony-stimulating factor (GM-CSF) generation and [(3)H]arachidonic acid (AA) release in response to interleukin-1beta and monocyte chemotactic protein (MCP)-1, respectively. These effects were abolished by PKIalpha. In contrast, H-89 behaved unpredictably under the same conditions. Thus, although CREB phosphorylation evoked by a range of cAMP-elevating drugs was abolished by H-89, neither activation of the CRE-dependent luciferase reporter gene construct nor the inhibition of GM-CSF generation was inhibited. Paradoxically, H-89 antagonized MCP-1-induced [(3)H]AA release and enhanced the inhibitory effect of submaximal concentrations of rolipram and 8-bromo-cAMP. We suggest that expression of PKIalpha in susceptible cells provides a simple and unambiguous way to assess the role of PKA in cAMP signaling and to probe the mechanism of action of other drugs and cAMP-dependent responses where the participation of PKA is equivocal. Furthermore, these data suggest that H-89 is not a selective inhibitor of PKA and should be avoided.

IL-1beta-dependent activation of NF-kappaB mediates PGE2 release via the expression of cyclooxygenase-2 and microsomal prostaglandin E synthase

Prostaglandin (PG) E2 release is induced in pulmonary A549 cells by the NF-kappaB-activating stimuli interleukin-1beta (IL-1beta) and phorbol 12-myristate 13-acetate (PMA). Adenoviral over-expression of IkappaBalphaDeltaN, a dominant NF-kappaB inhibitor, prevents NF-kappaB-dependent transcription and was used to qualify the role of NF-kappaB in the release of PGE2. IkappaBalphaDeltaN repressed IL-1beta-induced, but not PMA-induced, cycloxygenase-2 (COX-2) and microsomal prostaglandin E synthase (mPGES) expression. These data conclusively demonstrate a substantial role for NF-kappaB in the co-ordinate induction of COX-2, mPGES and in the corresponding release of PGE2 by IL-1beta. However, other pathways are primarily responsible for PGE2 release induced by PMA.

Influence of the pontine and medullary reticular formation on synchrony of gamma motoneurone discharge in the cat

Discharges of gamma motoneurones were recorded from cut filaments of the nerve to the gastrocnemius medialis muscle in the cat decerebrated at an intercollicular level. Gamma motoneurones exhibited a background discharge in the absence of intentional stimulation, or could be made to discharge by continuous, innocuous stimulation of the skin of the heel. The discharges were periodic and regular (low coefficient of variation of interspike intervals), and no correlation was observed between the discharges of pairs of individual gamma efferents. Electrolytic lesion of the ipsilateral pontine and medullary reticular formation in the nucleus subcoeruleus, the nucleus reticularis gigantocellularis or the nucleus reticularis magnocellularis, invariably decreased regularity of discharge and resulted in short term synchrony. Lesions of the peri-aqueductal grey, the nucleus raphe dorsalis or the midline raphe nuclei did not induce synchrony. Surgical lesions in the locus coeruleus caused irregular firing and synchrony only when the lesion extended into the adjacent nucleus subcoeruleus. We conclude that monoaminergic neurones of the nucleus subcoeruleus, or a closely associated tegmental field, with axons descending through the gigantocellularis and magnocellularis fields, are the most likely origin of the bulbospinal control of synchronizing influences on gamma motoneurone discharge.