p38 Mitogen-activated protein kinase-induced glucocorticoid receptor phosphorylation reduces its activity: role in steroid-insensitive asthma

Oxidants induce a corticosteroid-insensitive phosphorylation of histone 3 at serine 10 in monocytes

Oxidative stress enhances inflammation and reduces the effectiveness of corticosteroids, but the inflammatory signalling pathways induced by oxidants remain ill-defined. Phosphorylation of histone 3 at serine 10 (H3-Pser10) marks out a subset of inflammatory genes for transcription, several of which are induced in oxidant-associated inflammation. However, the influence of oxidants or of corticosteroids on this modification remains unknown. We assessed the regulation of H3-Pser10 by oxidants and lipopolysaccharide (LPS) in human blood monocytes and lung macrophages and the effectiveness of its abolition in controlling inflammatory gene expression in cells from asthmatic subjects compared to corticosteroids alone. Both oxidants and LPS promoted the induction of H3-Pser10 which was unaffected by corticosteroids. The induction of H3-Pser10 was mediated through p38α mitogen-activated protein kinase (MAPK) and IκB kinase 2 (IKK-2) signalling. Consequently, inhibitors of p38α MAPK or IKK-2 used in combination with dexamethasone were more effective at controlling inflammatory gene expression from monocytes and lung macrophages from asthmatic patients than the corticosteroid alone. Therefore, reduction of H3-Pser10 by inhibition of p38α MAPK or of IKK-2 may provide greater anti-inflammatory control than corticosteroids alone in oxidant-associated inflammation such as severe asthma.

Reversal of corticosteroid insensitivity by p38 MAPK inhibition in peripheral blood mononuclear cells from COPD

BACKGROUND

Corticosteroids (CS) have limited efficacy in the treatment of chronic obstructive pulmonary disease (COPD). p38 mitogen-activated protein kinase (MAPK) activation is increased in lung macrophages of COPD. We investigated whether p38 MAPK inhibition can modulate CS insensitivity of peripheral blood mononuclear cells (PBMCs) from patients with COPD.

METHODS

PBMCs from patients with COPD (n=8) or healthy smokers (n=8) were exposed to lipopolysaccharide (LPS) with a selective p38 MAPK inhibitor (GW856553; 10(-10)-10(-6) M), with dexamethasone (10(-10)-10(-6) M), or with both. Phosphorylated glucocorticoid receptor (GR) was measured by Western blot.

RESULTS

Baseline (P<0.01) and LPS-induced (P<0.05) CXCL8 release was greater in PBMCs from COPD compared to healthy smokers. Inhibition of LPS-induced CXCL8 release by dexamethasone (10(-6) M) was reduced, and baseline and LPS-induced p38 MAPK activation increased in PBMCs of COPD. GW856553 (10(-9) and 10(-10) M) synergistically increased the inhibitory effect of dexamethasone (10(-8) and 10(-6) M) on LPS-induced CXCL8 release in COPD. Similar results were obtained for IL-6 release. GW856553 inhibited dexamethasone- and LPS-activated phosphorylation of serine 211 on GR. CS insensitivity in COPD PBMCs is reversed by inhibition of p38 MAPK activity, partly by preventing phosphorylation of GR at serine 211.

CONCLUSION

p38 MAPK inhibition may be beneficial in COPD by restoring CS sensitivity.

Cytokine-induced loss of glucocorticoid function: effect of kinase inhibitors, long-acting β(2)-adrenoceptor [corrected] agonist and glucocorticoid receptor ligands

Acting on the glucocorticoid receptor (NR3C1), glucocorticoids are widely used to treat inflammatory diseases. However, glucocorticoid resistance often leads to suboptimal asthma control. Since glucocorticoid-induced gene expression contributes to glucocorticoid activity, the aim of this study was to use a 2 × glucocorticoid response element (GRE) reporter and glucocorticoid-induced gene expression to investigate approaches to combat cytokine-induced glucocorticoid resistance. Pre-treatment with tumor necrosis factor-α (TNF) or interleukin-1β inhibited dexamethasone-induced mRNA expression of the putative anti-inflammatory genes RGS2 and TSC22D3, or just TSC22D3, in primary human airway epithelial and smooth muscle cells, respectively. Dexamethasone-induced DUSP1 mRNA was unaffected. In human bronchial epithelial BEAS-2B cells, dexamethasone-induced TSC22D3 and CDKN1C expression (at 6 h) was reduced by TNF pre-treatment, whereas DUSP1 and RGS2 mRNAs were unaffected. TNF pre-treatment also reduced dexamethasone-dependent 2×GRE reporter activation. This was partially reversed by PS-1145 and c-jun N-terminal kinase (JNK) inhibitor VIII, inhibitors of IKK2 and JNK, respectively. However, neither inhibitor affected TNF-dependent loss of dexamethasone-induced CDKN1C or TSC22D3 mRNA. Similarly, inhibitors of the extracellular signal-regulated kinase, p38, phosphoinositide 3-kinase or protein kinase C pathways failed to attenuate TNF-dependent repression of the 2×GRE reporter. Fluticasone furoate, fluticasone propionate and budesonide were full agonists relative to dexamethasone, while GSK9027, RU24858, des-ciclesonide and GW870086X were partial agonists on the 2×GRE reporter. TNF reduced reporter activity in proportion with agonist efficacy. Full and partial agonists showed various degrees of agonism on RGS2 and TSC22D3 expression, but were equally effective at inducing CDKN1C and DUSP1, and did not affect the repression of CDKN1C or TSC22D3 expression by TNF. Finally, formoterol-enhanced 2×GRE reporter activity was also proportional to agonist efficacy and functionally reversed repression by TNF. As similar effects were apparent on glucocorticoid-induced gene expression, the most effective strategy to overcome glucocorticoid resistance in this model was addition of formoterol to high efficacy NR3C1 agonists.

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.

Increased phenotypic differentiation and reduced corticosteroid sensitivity of fibrocytes in severe asthma

BACKGROUND

Patients with severe asthma are less responsive to corticosteroid therapy and show increased airway remodeling. The mesenchymal progenitors, fibrocytes, may be involved in the remodeling of asthmatic airways. We propose that fibrocytes in severe asthma are different from those in nonsevere asthma.

OBJECTIVES

To examine the survival, myofibroblastic differentiation, and C-C chemokine receptor 7 (CCR7) expression in blood fibrocytes from patients with severe and nonsevere asthma and study the effect of corticosteroids on fibrocyte function.

METHODS

The nonadherent non-T-cell fraction of blood mononuclear cells was isolated from healthy subjects and patients with nonsevere and severe asthma. Total and differentiating fibrocytes were identified by their expression of CD45, collagen I, and α-smooth muscle actin using flow cytometry. The expression of CCR7 and of the glucocorticoid receptor was measured by using flow cytometry.

RESULTS

Increased numbers of circulating fibrocytes, with greater myofibroblastic differentiation potential, were observed in patients with severe asthma. Dexamethasone induced apoptosis, leading to reduction in the number of cultured fibrocytes and total nonadherent non-T cells from healthy subjects and patients with nonsevere asthma but not from patients with severe asthma. Dexamethasone reduced CCR7 expression in fibrocytes from patients with nonsevere asthma but not from patients with severe asthma. Glucocorticoid receptor expression was attenuated in fibrocytes from patients with severe asthma.

CONCLUSIONS

Patients with severe asthma have elevated numbers of circulating fibrocytes that show enhanced myofibroblastic differentiation and that are less responsive to the effects of corticosteroids.

PGE2 modulates the transcriptional activity of ERRa in prostate stromal cells

The regulation of the transcriptional activity of the estrogen receptor-related receptor a (ERRa) has not yet been clearly documented. Aromatase is a direct target gene of ERRa, and we previously reported that prostaglandin E2 (PGE2) increased the expression of ERRa in the prostate stromal cell line WPMY-1, which ultimately promoted estradiol production by enhancing aromatase gene transcription. Here, we show that PGE2 also affects aromatase expression by regulating ERRa transcriptional activity in prostate stromal cells. When the cells were cultured in serum-free medium, the expression of aromatase was not proportional to the ERRa protein level, if no other stimulation occurred, indicating the absence of a factor that activates ERRa. PGE2 could upregulate aromatase and ERRa response element (ERRE)-reporter expression and also enhance ERRa phosphorylation and nuclear localization. PGE2 functions through the PGE2 receptors (EP) 2 and EP4, which couple to adenylate cyclase. The activation of adenylate cyclase with Forskolin mimicked the PGE2-mediated enhancement of extracellular signal-regulated kinase (ERK) phosphorylation and ERRa target gene expression. Experiments using specific signaling pathway inhibitors showed that both phosphatidylinositol 3-kinase (PI3K) and ERK are involved in ERRa activation, and the PI3K inhibitor was shown to abolish ERK activation. Our results suggest that PGE2 is a modulator of ERRa transcriptional activity. Furthermore, PGE2 activates the EP2/EP4-cAMP-PI3K-ERK signaling pathway, which enhanced ERRa transcriptional potentiality by increasing ERRa phosphorylation and nuclear translocation, subsequently promoting the expression of its target genes, such as aromatase.

Increased frequency of dual-positive TH2/TH17 cells in bronchoalveolar lavage fluid characterizes a population of patients with severe asthma

BACKGROUND

TH2 cells can further differentiate into dual-positive TH2/TH17 cells. The presence of dual-positive TH2/TH17 cells in the airways and their effect on asthma severity are unknown.

OBJECTIVE

We sought to study dual-positive TH2/TH17 cells in bronchoalveolar lavage (BAL) fluid from asthmatic patients, examine their response to glucocorticoids, and define their relevance for disease severity.

METHODS

Bronchoscopy and lavage were performed in 52 asthmatic patients and 25 disease control subjects. TH2 and TH2/TH17 cells were analyzed by using multicolor flow cytometry and confocal immunofluorescence microscopy. Cytokines were assayed by means of ELISA.

RESULTS

Dual-positive TH2/TH17 cells were present at a higher frequency in BAL fluid from asthmatic patients compared with numbers seen in disease control subjects. High-level IL-4 production was typically accompanied by high-level IL-17 production and coexpression of GATA3 and retinoic acid receptor-related orphan receptor γt. Increased presence of TH2/TH17 cells was associated with increased IL-17 production in lavage fluid. TH2/TH17 cell counts and IL-17 production correlated with PC20 for methacholine, eosinophil counts, and FEV1. TH2/TH17 cells, unlike TH2 cells, were resistant to dexamethasone-induced cell death. They expressed higher levels of mitogen-activated protein-extracellular signal-regulated kinase kinase 1, a molecule that induces glucocorticoid resistance. On the basis of the dominance of BAL fluid TH2 or TH2/TH17 cells, we identified 3 subgroups of asthma: TH2(predominant), TH2/TH17(predominant), and TH2/TH17(low). The TH2/TH17(predominant) subgroup manifested the most severe form of asthma, whereas the TH2/TH17(low) subgroup had the mildest asthma.

CONCLUSION

Asthma is associated with a higher frequency of dual-positive TH2/TH17 cells in BAL fluid. The TH2/TH17(predominant) subgroup of asthmatic patients manifested glucocorticoid resistance in vitro. They also had the greatest airway obstruction and hyperreactivity compared with the TH2(predominant) and TH2/TH17(low) subgroups.

Novel agents in the future: Therapy beyond anti-TNF agents in inflammatory bowel disease

Anti-tumor necrosis factor (TNF)-α agents emerge as the hot spot in the last decade for treating patients with inflammatory bowel disease (IBD). The effect of anti-TNF-α agents is satisfactory; however, some patients fail to achieve clinical response. Fortunately, in recent years, great efforts have been made and multiple novel therapies have been developed in the treatment for IBD. In this article, we aim to introduce anti-TNF-α drugs as well as other novel treatments currently undergoing clinical trials for IBD.

Impact of ozone exposure on the response to glucocorticoid in a mouse model of asthma: involvements of p38 MAPK and MKP-1

Background

Molecular mechanisms involved in the oxidative stress induced glucocorticoids insensitivity remain elusive. The mitogen-activated protein kinase phosphatase (MKP) 1 mediates a part of glucocorticoids action and can be modified by exogenous oxidants. Whether oxidant ozone (O₃) can affect the function of MKP-1 and hence blunt the response to corticotherapy is not clear.

Methods

Here we employed a murine model of asthma established with ovalbumin (OVA) sensitization and challenge to evaluate the influence of O₃ on the inhibitory effect of dexamethasone on AHR and airway inflammation, and by administration of SB239063, a selective p38 MAPK inhibitor, to explore the underlying involvements of the activation of p38 MAPK and the expression of MKP-1.

Results

Ozone exposure not only aggravated the pulmonary inflammation and AHR, but also decreased the inhibitory effects of dexamethasone, accompanied by the elevated oxidative stress, airway neutrophilia, enhanced phosphorylation of p38 MAPK, and upregulated expression of IL-17. Administration of SB239063 caused significant inhibition of the p38 MAPK phosphorylation, alleviation of the airway neutrophilia, and decrement of the ozone-induced IL-17 expression, and partly restored the ozone-impaired effects of dexamethasone. Ozone exposure not only decreased the protein expression of MKP-1, but also diminished the dexamethasone-mediated induction process of MKP-1 mRNA and protein expression.

Conclusions

The glucocorticoids insensitivity elicited by ozone exposure on current asthma model may involve the enhanced phosphorylation of p38 MAPK and disturbed expression of MKP-1.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0126-x) contains supplementary material, which is available to authorized users.

Increased sputum endotoxin levels are associated with an impaired lung function response to oral steroids in asthmatic patients

BACKGROUND

Airway endotoxin might contribute to corticosteroid insensitivity in asthmatic patients.

OBJECTIVE

Because cigarette smoke contains endotoxin, we tested the hypothesis that sputum endotoxin concentrations are increased in cigarette smokers and that endotoxin concentrations are associated with corticosteroid insensitivity in asthmatic patients.

METHODS

Sixty-nine asthmatic patients (never smokers, smokers, and exsmokers) and 20 healthy subjects (never smokers and smokers) were recruited. Fifty-three asthmatic patients received a 2-week course of oral dexamethasone. Serum and induced sputum endotoxin and cytokine concentrations were quantified by using an enzyme immunoassay.

RESULTS

Median (interquartile range [IQR]) sputum endotoxin concentration were not significantly different between asthmatic never smokers (184 endotoxin units [EU]/mL; IQR, 91-310 EU/mL), exsmokers (123 EU/mL; IQR, 39-207 EU/mL), and smokers (177 EU/mL; IQR, 41-772 EU/mL; P = .703) and healthy subjects (164 EU/mL; IQR, 106-373 EU/mL). The lung function response to oral corticosteroids decreased with increasing sputum endotoxin concentrations in the never smokers (linear regression α = .05, Spearman r = -0.503, P = .009) but not in smokers (α = .587, r = -0.282, P = .257), as confirmed by using multiple regression analysis. Asthmatic smokers had higher concentrations of serum endotoxin than asthmatic nonsmokers (0.25 EU/mL [IQR, 0.09-0.39 EU/mL] vs 0.08 EU/mL [IQR, 0.05-0.19 EU/mL], P = .042) unrelated to steroid insensitivity or serum cytokine concentrations. In the asthmatic group sputum endotoxin concentrations correlated with sputum IL-1 receptor antagonist concentrations (r = 0.510, P < .001), and serum endotoxin concentrations significantly correlated with sputum IL-6, IL-8, and chemokine motif ligand 2 concentrations.

CONCLUSION

Asthmatic smokers have similar sputum endotoxin concentrations compared with those of asthmatic never smokers. The association between higher sputum endotoxin levels and an impaired lung function response to oral corticosteroids, particularly in asthmatic never smokers, suggests that airway endotoxin might contribute to corticosteroid insensitivity in asthmatic patients.

Mechanisms of glucocorticoid action and insensitivity in airways disease

Glucocorticoids are the mainstay for the treatment of chronic inflammatory diseases including asthma and chronic obstructive pulmonary disease (COPD). However, it has been recognized that glucocorticoids do not work well in certain patient populations suggesting reduced sensitivity. The ultimate biologic responses to glucocorticoids are determined by not only the concentration of glucocorticoids but also the differences between individuals in glucocorticoid sensitivity, which is influenced by multiple factors. Studies are emerging to understand these mechanisms in detail, which would help in increasing glucocorticoid sensitivity in patients with chronic airways disease. This review aims to highlight both classical and emerging concepts of the anti-inflammatory mechanisms of glucocorticoids and also review some novel strategies to overcome steroid insensitivity in airways disease.

Comprehensive overview of the structure and regulation of the glucocorticoid receptor

Glucocorticoids are among the most prescribed drugs worldwide for the treatment of numerous immune and inflammatory disorders. They exert their actions by binding to the glucocorticoid receptor (GR), a member of the nuclear receptor superfamily. There are several GR isoforms resulting from alternative RNA splicing and translation initiation of the GR transcript. Additionally, these isoforms are all subject to several transcriptional, post-transcriptional, and post-translational modifications, all of which affect the protein's stability and/or function. In this review, we summarize recent knowledge on the distinct GR isoforms and the processes that generate them. We also review the importance of all known transcriptional, post-transcriptional, and post-translational modifications, including the regulation of GR by microRNAs. Moreover, we discuss the crucial role of the putative GR-bound DNA sequence as an allosteric ligand influencing GR structure and activity. Finally, we describe how the differential composition and distinct regulation at multiple levels of different GR species could account for the wide and diverse effects of glucocorticoids.

Newer glucocorticosteroids and corticosteroid resistance reversal in asthma

Inflammation is the hallmark of asthma. Glucocorticosteroids inhibit this inflammation and are the mainstay of therapy in asthma, however, they suffer from their own drawbacks. They possess high potency but their continued use has a negative influence on health. Hence, quest for a steroid with good potency but without the undesirable effects is ongoing. Besides, steroid resistance is a problem in a substantial proportion of severe asthmatics. Deeper insight into the molecular mechanism of this refractoriness has led to the successful trial of certain drugs to overcome this problem. This review attempts to discuss some of the patents related to improved glucocorticoids and those agents that have the potential to restore steroid sensitivity in severe asthmatics.

Refractory asthma: mechanisms, targets, and therapy

Asthma is a common medical condition affecting 300 million people worldwide. Airway inflammation, smooth muscle bronchoconstriction leading to airflow obstruction, and mucous hypersecretion are clinical hallmarks of asthma. The NHLBI Expert Panel Report 3 recommends inhaled corticosteroids (ICS) for patients with moderate to severe persistent asthma. Inhaled corticosteroids (ICS) target gene transcription through their interactions with the glucocorticoid (GC) receptor (GR) at the glucocorticoid response element (GRE). The GC/GR complex enhances anti-inflammatory but inhibits pro-inflammatory mediator production. Classically, asthma has been described as a Th2-associated eosinophil-predominant disease, but recently alternative models have been described including a Th17-mediated neutrophil-predominant phenotype resulting in patients with more severe disease who may be less responsive to steroids. Additional mechanisms of steroid resistance include increased activity of GR phosphorylating kinases which modify the interactions of GR with transcription factors to inhibit the ability of GR to bind with GRE, leading to an increase in pro-inflammatory gene transcription. Oxidative stress also affects the balance between pro-inflammatory and anti-inflammatory gene transcription through the modification of transcription factors and cofactors (such as PI3K) leading to the inhibition of histone deacetylase 2. Continued investigations into the mechanisms behind glucocorticoid resistance will lead to novel treatments that improve control of severe refractory asthma.

Parainfluenza virus type 1 induces epithelial IL-8 production via p38-MAPK signalling

Human parainfluenza virus type 1 (HPIV-1) is the most common cause of croup in infants. The aim of this study was to describe molecular mechanisms associated with IL-8 production during HPIV-1 infection and the role of viral replication in MAPK synthesis and activation. An in vitro model of HPIV-1 infection in the HEp-2 and A549 cell lines was used; a kinetic-based ELISA for IL-8 detection was also used, phosphorylation of the mitogen-activated protein kinases (MAPKs) was identified by Western blot analysis, and specific inhibitors for each kinase were used to identify which MAPK was involved. Inactivated viruses were used to assess whether viral replication is required for IL-8 production. Results revealed a gradual increase in IL-8 production at different selected times, when phosphorylation of MAPK was detected. The secretion of IL-8 in the two cell lines infected with the HPIV-1 is related to the phosphorylation of the MAPK as well as viral replication. Inhibition of p38 suppressed the secretion of IL-8 in the HEp-2 cells. No kinase activation was observed when viruses were inactivated.

Fluoxetine signature on hippocampal MAPK signalling in sex-dependent manner

A growing body of evidence indicates that mitogen-activated protein kinase (MAPK) participates in various stress-induced responses and is considered to be one of the pathophysiological mechanisms in depression. Surprisingly, the effect of antidepressants on MAPKs is almost unexplored, particularly from the perspective of sexes. The present study investigates the cytoplasm-nuclear distribution of MAPK family, c-Jun N-terminal kinases (JNKs) 1, 2 and 3; extracellular signal-regulated kinases (ERKs) 1 and 2; and p38 kinases, as well as their phosphoisoforms in the hippocampus of chronically stressed female and male rats and upon chronic fluoxetine treatment. Additionally, we analysed crosstalk between MAPK signalling and depressive-like behaviour which correlated with brain-derived neurotrophic factor (BDNF) expression. Our results emphasize a gender-specific and compartment-dependent response of MAPKs to stress and fluoxetine. In females, stress decreased pp38 and pJNK and induced cytosolic retention of pERKs which reduced all nuclear pMAPKs. These changes correlated with altered BDNF expression and behaviour. Similarly, in males, stress decreased pp38 but promoted nuclear translocation of pJNKs and pERKs. These stress alterations of pMAPKs in males were not associated with BDNF expression and depressive-like behaviour. Fluoxetine treatment in stressed females upregulated whole pMAPK signalling particularly those in nucleus which was followed with BDNF expression and normalization of behaviour. In stressed males, fluoxetine affected only cytosolic pJNKs, while nuclear pMAPK signalling and BDNF expression were unaffected even though fluoxetine normalized behaviour. Overall, our results suggest existence of gender-specific mechanism of fluoxetine on nuclear pMAPK/BDNF signalling and depressive-like behaviour and reinforce the antidepressant dogma that females and males respond differently to certain antidepressants.

Basal p38 mitogen-activated protein kinase regulates unliganded glucocorticoid receptor function in airway smooth muscle cells

Like many steroid receptors, the glucocorticoid (GC) receptor (GR) is a phosphoprotein. Although there are multiple phosphorylation sites critical for GR transcriptional activity (i.e., serine [S]203, S211, and S226), their respective role in driving GR functions is highly cell specific. We have recently identified protein phosphatase 5 as an essential Ser/Thr phosphatase responsible for impairing GR function via S211 dephosphorylation in airway smooth muscle (ASM) cells. Because p38 mitogen-activated protein kinase (MAPK) directly phosphorylates GR in different cell types in a stimulus- and cell-dependent manner, we investigated the role of p38 MAPK on GR phosphorylation and function in ASM cells. Cells were transfected with 100 nM p38 MAPK small interfering RNA or 2 μg MAPK kinase 3 expression vector (a specific kinase that directly activates p38 MAPK) in the presence or absence of fluticasone (100 nM) and/or p38 MAPK pharmacological inhibitor SB203580. We found that p38 MAPK blockade positively regulates GR nuclear translocation and GR-dependent induction of the steroid-target gene GC-induced leucine zipper in a hormone-independent manner. We also found that p38 MAPK-dependent regulation of GR functions was associated with a differential action on GR phosphorylation at S203 and S211 residues. This study demonstrated that the inactive state of GR in resting conditions is not only ensured by the absence of the GC ligand but also by p38 MAPK-dependent phosphorylation of unliganded GR at specific residues, which appears to be important in determining the overall GC responsiveness of ASM cells.

Diagnosis and management of eosinophilic asthma: a US perspective

Eosinophilic asthma is now recognized as an important subphenotype of asthma based on the pattern of inflammatory cellular infiltrate in the airway. Eosinophilic asthma can be associated with increased asthma severity, atopy, late-onset disease, and steroid refractoriness. Induced sputum cell count is the gold standard for identifying eosinophilic inflammation in asthma although several noninvasive biomarkers, including fractional exhaled nitric oxide and periostin, are emerging as potential surrogates. As novel therapies and biologic agents become increasingly available, there is an increased need for specific phenotype-directed treatment strategies. Greater recognition and understanding of the unique immunopathology of this asthma phenotype has important implications for management of the disease and the potential to improve patient outcomes. The present review provides a summary of the clinical features, pathogenesis, diagnosis, and management of eosinophilic asthma.

The respiratory syncytial virus (RSV) nonstructural proteins mediate RSV suppression of glucocorticoid receptor transactivation

Respiratory syncytial virus (RSV)-induced bronchiolitis in infants is not responsive to glucocorticoids. We have shown that RSV infection impairs glucocorticoid receptor (GR) function. In this study, we have investigated the mechanism by which RSV impairs GR function. We have shown that RSV repression of GR-induced transactivation is not mediated through a soluble autocrine factor. Knock-down of mitochondrial antiviral signaling protein (MAVS), but not retinoic acid-inducible gene 1 (RIG-I) or myeloid differentiation primary response gene 88 (MyD88), impairs GR-mediated gene activation even in mock-infected cells. Over-expression of the RSV nonstructural protein NS1, but not NS2, impairs glucocorticoid-induced transactivation and viruses deleted in NS1 and/or NS2 are unable to repress glucocorticoid-induction of the known GR regulated gene glucocorticoid-inducible leucine zipper (GILZ). These data suggest that the RSV nonstructural proteins mediate RSV repression of GR-induced transactivation and that inhibition of the nonstructural proteins may be a viable target for therapy against RSV-related disease.

Inflammatory activation is associated with a reduced glucocorticoid receptor alpha/beta expression ratio in monocytes of inpatients with melancholic major depressive disorder

In this study, we used new technology to investigate whether a coherent pattern of enhanced expression of inflammatory and other immune activation genes in circulating monocytes is found in patients with major depression. Since a high inflammatory state of monocytes might be related to glucocorticoid resistance, we also included the genes for the two isoforms of the glucocorticoid receptor. For this study, we aimed at finding a similar coherent pattern of inflammatory and immune activation genes in monocytes of patients with MDD and recruited 47 medication-free melancholic MDD inpatients and 42 healthy controls. A quantitative-polymerase chain reaction (Q-PCR) monocyte gene expression analysis was performed using a panel of inflammatory-related genes previously identified as abnormally regulated in mood disorder patients. Selected serum cytokines/chemokines were assessed using a cytometric bead array. Depressive symptoms were analysed using Hamilton depression scores (HAMD). Thirty-four of the 47 monocyte inflammatory-related genes were significantly upregulated and 2 were significantly downregulated as compared to controls, the latter including the gene for the active GRα in particular in those with a high HAMD score. The reduced GRα expression correlated strongly to the upregulation of the inflammatory genes in monocytes. Serum levels of IL6, IL8, CCL2 and VEGF were significantly increased in patients compared to controls. Our data show the deregulation of two interrelated homoeostatic systems, that is, the immune system and the glucocorticoid system, co-occurring in major depression.

Dominance of the strongest: inflammatory cytokines versus glucocorticoids

Pro-inflammatory cytokines are involved in the pathogenesis of many inflammatory diseases, and the excessive expression of many of them is normally counteracted by glucocorticoids (GCs), which are steroids that bind to the glucocorticoid receptor (GR). Hence, GCs are potent inhibitors of inflammation, and they are widely used to treat inflammatory diseases, such as asthma, rheumatoid arthritis and inflammatory bowel disease. However, despite the success of GC therapy, many patients show some degree of GC unresponsiveness, called GC resistance (GCR). This is a serious problem because it limits the full therapeutic exploitation of the anti-inflammatory power of GCs. Patients with reduced GC responses often have higher cytokine levels, and there is a complex interplay between GCs and cytokines: GCs downregulate pro-inflammatory cytokines while cytokines limit GC action. Treatment of inflammatory diseases with GCs is successful when GCs dominate. But when cytokines overrule the anti-inflammatory actions of GCs, patients become GC insensitive. New insights into the molecular mechanisms of GR-mediated actions and GCR are needed for the design of more effective GC-based therapies.

Interleukin-6 is associated with steroid resistance and reflects disease activity in severe pediatric ulcerative colitis

BACKGROUND AND AIM

Approximately one third of patients with acute severe ulcerative colitis (ASC) will fail intravenous corticosteroids (IVCS). Predicting response to IVCS to initiate early salvage therapy remains challenging. The aim of this study was to evaluate the role of serum inflammatory cytokines in ASC and determine their predictive utility with IVCS treatment failure.

METHODS

This preplanned ancillary study, part of the prospective multicenter OSCI study, evaluated pediatric ASC in North America. Serum samples were obtained from 79 children admitted for ASC on the third day of IVCS treatment. Twenty-three (29%) patients required second-line therapy. ELISA-based cytokine arrays were used [TNF-α, IFN-γ, interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, and IL-17], selected based on a systematic literature search.

RESULTS

In univariate analysis, only IL-6 was significantly different between responders and non-responders (P=0.003). The risk for IVCS failure increased by 40% per each pg/mL increase in IL-6 level. Factor analysis found IL-6 to be associated with IL-17, suggesting involvement of the T-helper (TH)17 pathway. In a multivariate analysis, disease activity [judged by the Pediatric UC Activity Index (PUCAI)] assumed all the association with the treatment outcome while IL-6 was no longer significant (P=0.32; PUCAI score P<0.001).

CONCLUSIONS

While IL-6 strongly predicted IVCS failure, it likely reflects disease activity and not direct interference with corticosteroid pathway. Nonetheless, IL-6 levels may have a role in predicting IVCS response in severe pediatric UC for treatment decision-making or potentially in medical intervention by virtue of anti-IL-6 antibodies in severe UC.

How variability in clinical phenotypes should guide research into disease mechanisms in asthma

Asthma is increasingly being considered as a collection of different phenotypes that present with intermittent wheezing. Unbiased approaches to classifying asthma have led to the identification of distinct phenotypes based on age of onset of disease, atopic state, disease severity or activity, degree of chronic airflow obstruction, and sputum eosinophilia. Linking phenotypes to known disease mechanism is likely to be more fruitful in determining the potential targets necessary for successful therapies of specific endotypes. A "Th2-high expression" signature from the epithelium of patients with asthma identifies a subset of patients with high eosinophilia and good therapeutic responsiveness to corticosteroids. Other characteristic traits of asthma include noneosinophilic asthma, corticosteroid insensitivity, obesity-associated, and exacerbation-prone. Further progress into asthma mechanisms will be driven by unbiased data integration of multiscale data sets from omics technologies with those phenotypic characteristics and by using mathematical modeling. This will lead to the discovery of new pathways and their integration into endotypes and also set up further hypothesis-driven research. Continued iteration through experimentation or modeling will be needed to refine the phenotypes that relate to outcomes and also delineate specific treatments for specific phenotypes.

The role of macrophages in obstructive airways disease: chronic obstructive pulmonary disease and asthma

Macrophages are a major cellular component of the innate immune system, and play an important role in the recognition of microbes, particulates, and immunogens and to the regulation of inflammatory responses. In the lung, macrophages react with soluble proteins that bind microbial products in order to remove pathogens and particles and to maintain the sterility of the airway tract. Chronic obstructive pulmonary disease and asthma are both obstructive airway diseases that involve chronic inflammation of the respiratory tract which contributes to disease progression. In the case of COPD, there is increasing evidence that lung macrophages orchestrate inflammation through the release of chemokines that attract neutrophils, monocytes and T cells and the release of several proteases. On the other hand, in asthma, it seems that alveolar macrophages are inappropriately activated and are implicated in the development and progression of the disease. In this review we summarize the current basic and clinical research studies which highlight the role of macrophages in asthma and COPD.

Glucocorticoid-resistant asthma: more than meets the eye

INTRODUCTION

For decades glucocorticoids have been considered as the gold standard for the treatment of asthma. We present a case report of typical glucocorticoid-resistant asthma and current consensus in definitions of "severe refractory", "difficult" and "glucocorticoid-resistant" asthma.

METHODS

Full-text papers and abstracts were identified on the basis of a comprehensive literature search primarily in MEDLINE (1966 to June 2012) but also in the Cochrane Central Register of Controlled Trials database.

RESULTS

Glucocorticoid-resistant asthmatics are a small subset of patients who pose noteworthy diagnostic challenges while contributing disproportionately to health care costs. Recognition of various asthma phenotypes has aided in characterizing groups with severe asthma and given a better understanding of its pathophysiological process. The molecular mechanism of glucocorticoid action is complicated and several pathways have been identified to explain drug resistance, which in turn is crucial for drug development. Tobacco smoking appears to be the single most important contributor of glucocorticoid resistance. We present the emerging and promising concepts in the management of glucocorticoid-resistant asthma, which mainly include drugs targeting specific molecules, receptors, inflammatory cells or immune processes.

CONCLUSION

The challenges in making a diagnosis of glucocorticoid-resistant asthma may contribute to underestimating its prevalence and impact on patient care. Considerable progress has been made in identifying distinct phenotypes and mechanisms of glucocorticoid resistance; therefore the future of new drug development in management of asthma is promising.

The impact of escitalopram on IL-2-induced neuroendocrine, immune, and behavioral changes in patients with malignant melanoma: preliminary findings

Interleukin (IL)-2, a T-cell cytokine used to treat malignant melanoma, can induce profound depression. To determine whether pretreatment with the antidepressant escitalopram could reduce IL-2-induced neuroendocrine, immune, and neurobehavioral changes, 20 patients with Stage IV melanoma were randomized to either placebo or the serotonin reuptake inhibitor, escitalopram (ESC) 10-20 mg/day, 2 weeks before, and during IL-2 treatment (720 000 units/kg Q8 h × 5 days (1 cycle) every 3 weeks × 4 cycles). Generalized estimation equations were used to examine HPA axis activity (plasma ACTH and cortisol), immune activation (plasma IL-6), and depressive symptoms (Hamilton Depression Rating Scale (HDRS) score). Tolerance of IL-2 treatment (concomitant medications required) and adherence (number of IL-2 doses received) were also assessed. Both the groups (ESC (n=9), placebo (n=11)) exhibited significant IL-2-induced increases in plasma cortisol, IL-6, and depressive symptoms (p<0.05), as well as a temporal trend for increases in plasma ACTH (p=0.054); the effects of age and treatment were not significant. Higher plasma ACTH concentrations were associated with higher depressive symptoms during cycles 1-3 of IL-2 therapy (p<0.01). Although ESC had no significant effects on ACTH, cortisol, IL-6, tolerance of, or adherence to IL-2, ESC treatment was associated with lower depressive symptoms, ie, a maximal difference of ∼3 points on the HDRS, which, though not statistically significant (in part, due to small sample size), represents a clinically significant difference according to the National Institute for Health and Clinical Excellence guidelines. A larger sample size will establish whether antidepressant pretreatment can prevent IL-2-induced neurobehavioral changes.

Smoking in asthma is associated with elevated levels of corticosteroid resistant sputum cytokines-an exploratory study

Background

Current cigarette smoking is associated with reduced acute responses to corticosteroids and worse clinical outcomes in stable chronic asthma. The mechanism by which current smoking promotes this altered behavior is currently unclear. Whilst cytokines can induce corticosteroid insensitivity in-vitro, how current and former smoking affects airway cytokine concentrations and their responses to oral corticosteroids in stable chronic asthma is unclear.

Objectives

To examine blood and sputum cytokine concentrations in never, ex and current smokers with asthma before and after oral corticosteroids.

Methods

Exploratory study utilizing two weeks of oral dexamethasone (equivalent to 40 mg/day prednisolone) in 22 current, 21 never and 10 ex-smokers with asthma. Induced sputum supernatant and plasma was obtained before and after oral dexamethasone. 25 cytokines were measured by multiplex microbead system (Invitrogen, UK) on a Luminex platform.

Results

Smokers with asthma had elevated sputum cytokine interleukin (IL) -6, -7, and -12 concentrations compared to never smokers with asthma. Few sputum cytokine concentrations changed in response to dexamethasone IL-17 and IFNα increased in smokers, CCL4 increased in never smokers and CCL5 and CXCL10 reduced in ex-smokers with asthma. Ex-smokers with asthma appeared to have evidence of an ongoing corticosteroid resistant elevation of cytokines despite smoking cessation. Several plasma cytokines were lower in smokers with asthma compared to never smokers with asthma.

Conclusion

Cigarette smoking in asthma is associated with a corticosteroid insensitive increase in multiple airway cytokines. Distinct airway cytokine profiles are present in current smokers and never smokers with asthma and could provide an explanatory mechanism for the altered clinical behavior observed in smokers with asthma.

New treatments for severe treatment-resistant asthma: targeting the right patient

Guidelines for asthma management focus on the use of combination inhaled treatment with corticosteroids and longacting β-agonists for symptomatic asthma. In more severe disease, other drugs such as leukotriene blockers and slow-release oral theophylline are added, with oral corticosteroids and anti-immunoglobulin E treatment with omalizumab for the most severe cases of asthma. Once-daily longacting β-agonists and inhaled corticosteroids are being developed. Longacting muscarinic antagonists might also provide additive benefit. New approaches are needed for the treatment of severe asthma, but patients need to be endotyped so that they can be directed for specific treatments. This Review focuses on the role of eosinophilic and neutrophilic inflammation, the attributes of chronic airflow obstruction, and the notion of corticosteroid insensitivity because potential targets for treatment have started to emerge from such analyses. How the best phenotypic or even better, the best endotypic responder with each new treatment, can be established will also be discussed. Newer treatments for asthma will emerge from better endotyping, leading to personalised medicine in asthma.

Expression of the glucocorticoid receptor is decreased in experimental Staphylococcus aureus sepsis

INTRODUCTION

Glucocorticoid treatment in septic shock remains controversial after recent trials. We hypothesized that failure to respond to steroid therapy may be caused by decreased expression and/or function of glucocorticoid receptors (GR) and studied this in a mouse model of Staphylococcus aureus sepsis. The impact of timing of dexamethasone treatment was also investigated.

METHODS

Male C57BL/6J mice were intravenously inoculated with S. aureus and GR expression and binding ability in blood, spleen and lymph nodes were analysed by means of flow cytometry. GR translocation was analysed using Image Stream. Septic mice were administered dexamethasone at 22, 26, 48, 72 and 96 h after inoculation and body weight, as a sign of dehydration, was observed.

RESULTS

GR expression was decreased in septic animals, but not the ligand binding capacity. GR translocation was decreased in septic mice compared to control animals. Early dexamethasone treatment (22 and 26 h) improved clinical outcome as studied by weight gain compared to when treatment was started at later time points (48, 72 and 96 h).

CONCLUSION

Our data provide evidence that GR expression is progressively decreased in experimental sepsis and that dexamethasone has a decreased ability to translocate into the cell nucleus. This may explain why steroid treatment is only beneficial when administered early in sepsis and septic shock.

Functional KCa3.1 channels regulate steroid insensitivity in bronchial smooth muscle cells

Identifying the factors responsible for relative glucocorticosteroid (GC) resistance present in patients with severe asthma and finding tools to reverse it are of paramount importance. In asthma we see in vivo evidence of GC-resistant pathways in airway smooth muscle (ASM) bundles that can be modeled in vitro by exposing cultured ASM cells to TNF-α/IFN-γ. This action drives GC insensitivity via protein phosphatase 5-dependent impairment of GC receptor phosphorylation. In this study, we investigated whether KCa3.1 ion channels modulate the activity of GC-resistant pathways using our ASM model of GC insensitivity. Immunohistochemical staining of endobronchial biopsies revealed that KCa3.1 channels are localized to the plasma membrane and nucleus of ASM in both healthy controls and asthmatic patients, irrespective of disease severity. Western blot assays and immunofluorescence staining confirmed the nuclear localization of KCa3.1 channels in ASM cells. The functional importance of KCa3.1 channels in the regulation of GC-resistant chemokines induced by TNF-α/IFN-γ was assessed using complementary inhibitory strategies, including KCa3.1 blockers (TRAM-34 and ICA-17043) or KCa3.1-specific small hairpin RNA delivered by adenoviruses. KCa3.1 channel blockade led to a significant reduction of fluticasone-resistant CX3CL1, CCL5, and CCL11 gene and protein expression. KCa3.1 channel blockade also restored fluticasone-induced GC receptor-α phosphorylation at Ser(211) and transactivation properties via the suppression of cytokine-induced protein phosphatase 5 expression. The effect of KCa3.1 blockade was evident in ASM cells from both healthy controls and asthmatic subjects. In summary, KCa3.1 channels contribute to the regulation of GC-resistant inflammatory pathways in ASM cells: blocking KCa3.1 channels may enhance corticosteroid activity in severe asthma.

Pin1 promotes GR transactivation by enhancing recruitment to target genes

The glucocorticoid receptor (GR) is a ligand activated transcription factor, serving to regulate both energy metabolism and immune functions. Factors that influence cellular sensitivity to glucocorticoids (GC) are therefore of great interest. The N-terminal of the GR contains numerous potential proline-directed phosphorylation sites, some of which can regulate GR transactivation. Unrestricted proline isomerisation can be inhibited by adjacent serine phosphorylation and requires a prolyl isomerise, Pin1. Pin1 therefore determines the functional outcome of proline-directed kinases acting on the GR, as cis/trans isomers are distinct pools with different interacting proteins. We show that Pin1 mediates GR transactivation, but not GR trans-repression. Two N-terminal GR serines, S203 and S211, are targets for Pin1 potentiation of GR transactivation, establishing a direct link between Pin1 and the GR. We also demonstrate GC-activated co-recruitment of GR and Pin1 to the GILZ gene promoter. The Pin1 effect required both its WW and catalytic domains, and GR recruitment to its GRE was Pin1-dependent. Therefore, Pin1 is a selective regulator of GR transactivation, acting through N-terminal phospho-serine residues to regulate GR recruitment to its target sites in the genome. As Pin1 is dysregulated in disease states, this interaction may contribute to altered GC action in inflammatory conditions.

Asthma phenotypes and endotypes

PURPOSE OF REVIEW

It is increasingly clear that asthma is not a single disease, but a disorder with vast heterogeneity in pathogenesis, severity, and treatment response. In this review, we discuss the present understanding of different asthma phenotypes and endotypes, and the prospects of personalized medicine for asthma.

RECENT FINDINGS

The recognition of diverse biological backgrounds in which asthma, and particularly severe asthma, can manifest has prompted the search for refined phenotypes and endotypes in asthma. Such appreciation of the heterogeneity in asthma is also prompting clinical trials to focus on specific subgroups of asthma, as demonstrated by the clinical trial of lebrikizumab.

SUMMARY

Patients with severe asthma have asthma symptoms that are difficult to control, require high dosages of medication, and continue to experience persistent symptoms, asthma exacerbations or airflow obstruction even with aggressive therapy. Although asthma is traditionally viewed as an eosinophilic inflammatory disorder associated with a T-helper cell type 2 (Th2) immune response, recent studies have identified involvement of other effector cells, nonclassical Th2 cytokines and non-Th2 cytokines in severe asthma pathogenesis. Results of several clinical trials of anticytokine antibodies demonstrated the effectiveness of tailoring asthma treatment on the basis of an individual's biology.

Asthma: beyond corticosteroid treatment

Asthma is one of the most common chronic diseases in the world, affecting over 300 million people. It is an inflammatory disorder characterized by bronchoconstriction and airway hyperresponsiveness, followed by inflammatory manifestations in the respiratory system. The prevalence of asthma is rising and there is a clinical need to develop more effective treatments. While corticosteroids (glucocorticosteroids) remain the mainstay of asthma therapy, they have limitations because of their potentially severe side-effects and the presence of corticosteroid resistance in some patients. This review discusses current strategies in the treatment of asthma and considers new therapeutic regimens of asthma in the drug development pipeline.

Evaluation of glucocorticoid receptor function in COPD lung macrophages using beclomethasone-17-monopropionate

Previous studies of glucocorticoid receptor (GR) function in COPD lung macrophages have used dexamethasone to evaluate inhibition of cytokine production. We have now used the clinically relevant corticosteroid beclomethasone-17-monopropionate (17-BMP) to assess GR function in COPD lung macrophages, and investigated the transactivation of glucocorticoid sensitive genes and GR phosphorylation in addition to cytokine production. Lung macrophages were purified from surgically acquired lung tissue, from patients with COPD, smokers, and non-smokers. The transactivation of glucocorticoid sensitive genes (FKBP51 and GILZ) by 17-BMP were analysed by polymerase chain reaction. 17-BMP suppression of LPS-induced TNFα, IL-6 and CXCL8 was measured by ELISA and GR phosphorylation was measured by immunohistochemistry and Western blot. 17-BMP reduced cytokine release in a concentration dependent manner, with >70% inhibition of all cytokines, and no difference between COPD patients and controls. Similarly, the transactivation of FKBP51 and GILZ, and GR phosphorylation was similar between COPD patients and controls. In this context, GR function in COPD lung macrophages is unaltered. 17-BMP effectively suppresses cytokine production in COPD lung macrophages.

Circulating cortisol-associated signature of glucocorticoid-related gene expression in subcutaneous fat of obese subjects

OBJECTIVE

Serum cortisol concentrations fluctuate in a circadian fashion, and glucocorticoids exert strong effects on adipose tissue and induce obesity through the glucocorticoid receptor.

DESIGN AND METHODS

To examine the impact of physiologic levels of circulating cortisol on subcutaneous adipose tissue, 25 overweight and obese subjects were employed, and their serum levels of morning (AM) and evening (PM) cortisol, AM/PM cortisol ratios, and 24-h urinary-free cortisol (UFC) were compared with their clinical parameters, serum cytokine levels, and mRNA expression of 93 receptor action-regulating and 93 glucocorticoid-responsive genes in abdominal subcutaneous fat.

RESULTS AND CONCLUSIONS

AM cortisol levels did not correlate with mRNA expression of the all genes examined, whereas PM cortisol levels, AM/PM cortisol ratios, and 24-h UFC were associated with distinct sets of these genes. Body mass index did not significantly correlate with the four cortisol parameters employed. These results suggest that physiologic levels of AM serum cortisol do not solely represent biological effects of circulating cortisol on the expression of glucocorticoid-related genes in subcutaneous adipose tissue, whereas PM levels, amplitude, and net amounts of the diurnally fluctuating serum cortisol have distinct effects. Through the genes identified in this study, glucocorticoids appear to influence intermediary metabolism, energy balance, inflammation, and local circadian rythmicity in subcutaneous fat. Our results may also explain in part the development of metabolic abnormality and obesity in subjects under stress or patients with melancholic/atypical depression who demonstrate elevated levels of PM serum cortisol.

Pro-asthmatic cytokines regulate unliganded and ligand-dependent glucocorticoid receptor signaling in airway smooth muscle

To elucidate the regulation of glucocorticoid receptor (GR) signaling under pro-asthmatic conditions, cultured human airway smooth muscle (HASM) cells were treated with proinflammatory cytokines or GR ligands alone and in combination, and then examined for induced changes in ligand-dependent and -independent GR activation and downstream signaling events. Ligand stimulation with either cortisone or dexamethsone (DEX) acutely elicited GR translocation to the nucleus and, comparably, ligand-independent stimulation either with the Th2 cytokine, IL-13, or the pleiotropic cytokine combination, IL-1β/TNFα, also acutely evoked GR translocation. The latter response was potentiated by combined exposure of cells to GR ligand and cytokine. Similarly, treatment with either DEX or IL-13 alone induced GR phosphorylation at its serine-211 residue (GR^Ser211), denoting its activated state, and combined treatment with DEX+IL-13 elicited heightened and sustained GR^Ser211 phosphorylation. Interestingly, the above ligand-independent GR responses to IL-13 alone were not associated with downstream GR binding to its consensus DNA sequence or GR transactivation, whereas both DEX-induced GR:DNA binding and transcriptional activity were significantly heightened in the presence of IL-13, coupled to increased recruitment of the transcriptional co-factor, MED14. The stimulated GR signaling responses to DEX were prevented in IL-13-exposed cells wherein GR^Ser211 phosphorylation was suppressed either by transfection with specific serine phosphorylation-deficient mutant GRs or treatment with inhibitors of the MAPKs, ERK1/2 and JNK. Collectively, these novel data highlight a heretofore-unidentified homeostatic mechanism in HASM cells that involves pro-asthmatic cytokine-driven, MAPK-mediated, non-ligand-dependent GR activation that confers heightened glucocorticoid ligand-stimulated GR signaling. These findings raise the consideration that perturbations in this homeostatic cytokine-driven GR signaling mechanism may be responsible, at least in part, for the insensirtivity to glucocorticoid therapy that is commonly seen in individuals with severe asthma.

Role of transcription factors in the pathogenesis of asthma and COPD

Inflammation is a central feature of asthma and chronic obstructive pulmonary disease (COPD). Despite recent advances in the knowledge of the pathogenesis of asthma and COPD, much more research on the molecular mechanisms of asthma and COPD are needed to aid the logical development of new therapies for these common and important diseases, particularly in COPD where no effective treatments currently exist. In the future the role of the activation/repression of different transcription factors and the genetic regulation of their expression in asthma and COPD may be an increasingly important aspect of research, as this may be one of the critical mechanisms regulating the expression of different clinical phenotypes and their responsiveness to therapy, particularly to anti-inflammatory drugs.

Glycyrrhizic acid and 18β-glycyrrhetinic acid recover glucocorticoid resistance via PI3K-induced AP1, CRE and NFAT activation

Glucocorticoids are widely used in the clinical setting as remedies for inflammatory diseases, such as asthma and chronic obstructive pulmonary disease. However, the constant increase in the number of patients suffering from glucocorticoid resistance could present a serious problem for clinicians. In these cases, it may be reasonable to use additional treatments to restore the therapeutic effect of glucocorticoids. Glycyrrhizic acid (GA) and 18β-glycyrrhetinic acid (18βGA) are bioactive compounds in licorice that have been used for thousands of years in traditional Chinese medicine to treat coughs. We showed that GA and 18βGA exhibit potential anti-inflammatory and antioxidant properties. GA and 18βGA induced dual specificity protein phosphatase 1 (DUSP1) expression, and this effect was unchanged by the addition of RU486, a glucocorticoid receptor antagonist. The stimulation of DUSP1 expression by GA and 18βGA occurred via both glucocorticoid receptor (GR) and PI3K signaling, and the simultaneous activation of transcription elements, such as AP1 (activator protein 1), CRE (cAMP response element), GRE (glucocorticoid receptor element) and NFAT (nuclear factor of activated T-cells), was confirmed. Furthermore, we designed an in vitro glucocorticoid resistance model to verify the effects of GA and 18βGA on glucocorticoid resistance that was induced by ROS. The data showed that these two phytochemicals restored glucocorticoid sensitivity by depleting ROS through HO-1 expression. p38 and NO, which are factors that are induced by reactive oxygen species and caused depletion of GR signaling, were inhibited by GA and 18βGA treatment. This phenomenon was considered to be related to the coordinated modulation of GR and PI3K signaling by GA and 18βGA, in conjugation with AP1, CRE, GRE and NFAT activation. This study provides a possible strategy for enhancing the efficacy of glucocorticoids and may improve the prognosis of patients with serious inflammatory diseases.

Corticosteroid insensitivity is reversed by formoterol via phosphoinositide-3-kinase inhibition

BACKGROUND AND PURPOSE

Patients with chronic obstructive pulmonary disease (COPD) show a poor response to corticosteroids, which has been linked to oxidative stress. Here we show that the long-acting β(2) -agonist formoterol (FM) reversed corticosteroid insensitivity under oxidative stress via inhibition of phosphoinositide-3-kinase (PI3K) signalling.

EXPERIMENTAL APPROACH

Responsiveness to corticosteroids dexamethasone (Dex), budesonide (Bud) and fluticasone propionate (FP) was determined, as IC(50) values on TNF-α-induced interleukin 8 release, in U937 monocytic cell line treated with hydrogen peroxide (H(2) O(2) ) or peripheral blood mononuclear cells (PBMCs) from patients with COPD or severe asthma.

KEY RESULTS

PBMCs from severe asthma and COPD were less sensitive to Dex compared with those from healthy subjects. Both FM (10(-9)  M) and salmeterol (SM, 10(-8)  M) reversed Dex insensitivity in severe asthma, but only FM restored Dex sensitivity in COPD. Although H(2) O(2) exposure decreased steroid sensitivity in U937 cells, FM restored responsiveness to Bud and FP while the effects of SM were weaker. Additionally, FM, but not SM, partially inhibited H(2) O(2) -induced PI3Kδ-dependent (PKB) phosphorylation. H(2) O(2) decreased SM-induced cAMP production in U937 cells, but did not significantly affect the response to FM. The reduction of SM effects by H(2) O(2) was reversed by pretreatment with LY294002, a PI3K inhibitor, or IC87114, a PI3Kδ inhibitor.

CONCLUSION AND IMPLICATIONS

FM reversed oxidative stress-induced corticosteroid insensitivity and decreased β(2) adrenoceptor-dependent cAMP production via inhibition of PI3Kδ signalling. FM will be more effective than SM, when combined with corticosteroids, for the treatment of respiratory diseases under conditions of high oxidative stress, such as in COPD.

Corticosteroid resistance in patients with asthma and chronic obstructive pulmonary disease

Reduced responsiveness to the anti-inflammatory effects of corticosteroids is a major barrier to effective management of asthma in smokers and patients with severe asthma and in the majority of patients with chronic obstructive pulmonary disease (COPD). The molecular mechanisms leading to steroid resistance are now better understood, and this has identified new targets for therapy. In patients with severe asthma, several molecular mechanisms have been identified that might account for reduced steroid responsiveness, including reduced nuclear translocation of glucocorticoid receptor (GR) α after binding corticosteroids. This might be due to modification of the GR by means of phosphorylation as a result of activation of several kinases (p38 mitogen-activated protein kinase α, p38 mitogen-activated protein kinase γ, and c-Jun N-terminal kinase 1), which in turn might be due to reduced activity and expression of phosphatases, such as mitogen-activated protein kinase phosphatase 1 and protein phosphatase A2. Other mechanisms proposed include increased expression of GRβ, which competes with and thus inhibits activated GRα; increased secretion of macrophage migration inhibitory factor; competition with the transcription factor activator protein 1; and reduced expression of histone deacetylase (HDAC) 2. HDAC2 appears to mediate the action of steroids to switch off activated inflammatory genes, but in patients with COPD, patients with severe asthma, and smokers with asthma, HDAC2 activity and expression are reduced by oxidative stress through activation of phosphoinositide 3-kinase δ. Strategies for managing steroid resistance include alternative anti-inflammatory drugs, but a novel approach is to reverse steroid resistance by increasing HDAC2 expression, which can be achieved with theophylline and phosphoinositide 3-kinase δ inhibitors. Long-acting β2-agonists can also increase steroid responsiveness by reversing GRα phosphorylation. Identifying the molecular mechanisms of steroid resistance in asthmatic patients and patients with COPD can thus lead to more effective anti-inflammatory treatments.

Interleukin-13 signaling and its role in asthma

Asthma affects nearly 300 million people worldwide. The majority respond to inhaled corticosteroid treatment with or without beta-adrenergic agonists. However, a subset of 5 to 10% with severe asthma do not respond optimally to these medications. Different phenotypes of asthma may explain why current therapies show limited benefits in subgroups of patients. Interleukin-13 is implicated as a central regulator in IgE synthesis, mucus hypersecretion, airway hyperresponsiveness, and fibrosis. Promising research suggests that the interleukin-13 pathway may be an important target in the treatment of the different asthma phenotypes.

The structural basis of direct glucocorticoid-mediated transrepression

A newly discovered negative glucocorticoid response element (nGRE) mediates DNA-dependent transrepression by the glucocorticoid receptor (GR) across the genome and plays a major role in immunosuppressive therapy. The nGRE differs dramatically from activating response elements and the mechanism driving GR binding and transrepression is unknown. To unravel the mechanism of nGRE-mediated transrepression by the glucocorticoid receptor, we characterize the interaction between GR and a nGRE in the thymic stromal lymphopoetin (TSLP) promoter. We show using structural and mechanistic approaches that nGRE binding represents a new mode of sequence recognition by human GR and that nGREs prevent receptor dimerization through a unique GR-binding orientation and strong negative cooperativity, ensuring the presence of monomeric GR at repressive elements.

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.

Single nucleotide polymorphisms of NR3C1 gene and recurrent depressive disorder in population of Poland

Depressive disorder is a disease characterized by disturbances in the hypothalamo-pituitary-adrenal axis. Abnormalities include the increased level of glucocorticoids (GC) and changes in sensitivity to these hormones. The changes are related to glucocorticoid receptors gene (NR3C1) variants. The NR3C1 gene is suggested to be a candidate gene affecting depressive disorder risk and management. The aim of this study was to investigate polymorphisms within the NR3C1 gene and their role in the susceptibility to recurrent depressive disorder (rDD). 181 depressive patients and 149 healthy ethnically matched controls were included in the study. Single nucleotide polymorphisms were assessed using polymerase chain reaction/restriction fragment length polymorphism method. Statistical significance between rDD patients and controls was observed for the allele and genotype frequencies at three loci: BclI, N363S, and ER22/23EK. The presence of C allele, CC, and GC genotype of BclI polymorphism, G allele and GA genotype for N363S and ER22/23EK variants respectively were associated with increased rDD risk. Two haplotypes indicated higher susceptibility for rDD, while haplotype GAG played a protective role with OR(dis) 0.29 [95 % confidence interval (CI) = 0.13-0.64]. Data generated from this study support the earlier results that genetic variants of the NR3C1 gene are associated with rDD and suggest further consideration on the possible involvement of these variants in etiology of the disease.