Glucocorticoids reverse IL-1beta-induced impairment of beta-adrenoceptor-mediated relaxation and up-regulation of G-protein-coupled receptor kinases

α and β Catalytic Subunits of cAMP-dependent Protein Kinase Regulate Formoterol-induced Inflammatory Gene Expression Changes in Human Bronchial Epithelial Cells

BACKGROUND & PURPOSE

It has been proposed that genomic mechanisms contribute to the adverse-effects that are often experienced by asthmatic subjects who take regular, inhaled β₂ -adrenoceptor agonists as a monotherapy. Moreover, data from preclinical models of asthma suggest that these gene expression changes are mediated by β-arrestin-2 rather than PKA. Herein, we tested this hypothesis by comparing the genomic effects of formoterol, a β₂ -adrenoceptor agonist, with forskolin in human primary bronchial epithelial cells (HBEC).

EXPERIMENTAL APPROACH

Gene expression changes were determined by RNA-sequencing. Gene silencing and genome editing were employed to explore the roles of β-arrestin-2 and PKA.

KEY RESULTS

The formoterol-regulated transcriptome in HBEC treated concurrently with TNFα, was defined by 1480 unique gene expression changes. TNFα-induced transcripts modulated by formoterol were annotated with enriched gene ontology terms related to inflammation and proliferation, notably "GO:0070374~positive regulation of ERK1 and ERK2 cascade", which is an established β-arrestin-2 target. However, expression of the formoterol- and forskolin-regulated transcriptomes were highly rank-order correlated and the effects of formoterol on TNFα-induced inflammatory genes were abolished by an inhibitor of PKA. Furthermore, formoterol-induced gene expression changes in BEAS-2B bronchial epithelial cell clones deficient in β-arrestin-2 were comparable to those expressed by their parental counterparts. Contrariwise, gene expression was partially inhibited in clones lacking the α-catalytic subunit (Cα) of PKA and abolished following the additional knockdown of the β-catalytic subunit (Cβ) paralogue.

CONCLUSIONS

The effects of formoterol on inflammatory gene expression in airway epithelia are mediated by PKA and involve the cooperation of PKA-Cα and PKA-Cβ.

Indacaterol/glycopyrronium/mometasone fixed dose combination for uncontrolled asthma

INTRODUCTION

Asthma symptoms can be relieved through a maintenance treatment combining long-acting β₂-agonist and inhaled corticosteroids (LABA/ICS). However, for patients with inadequately controlled asthma, the LABA/ICS combination might not be sufficient, and clinical guidelines recommend the administration of inhaled long-acting muscarinic antagonists (LAMA) as an add-on therapy to better control asthma and improve lung function. For nearly two decades, the only LAMA to be approved on the market has been tiotropium.

AREAS COVERED

We reviewed recent clinical studies evaluating the safety and efficacy of LABA/LAMA/ICS fixed dose combinations by searching the PubMed database. Molecular mechanisms and clinical data support the use of a once-daily, single-inhaler fixed dose combination of the LABA/LAMA/ICS indacaterol/glycopyrronium/mometasone (IND/GLY/MF), the first therapy combining three agents in a fixed dose approved in Europe for the treatment of uncontrolled asthma.

EXPERT OPINION

IND/GLY/MF was superior to both IND/MF and salmeterol/fluticasone, a well-established LABA/ICS combination improving the lung function in uncontrolled asthma. Moreover, IND/GLY/MF, delivered through the Breezhaler inhaler in a single inhalation, is the first inhaled therapy prescribed alongside a digital companion, a sensor and the Propeller app, allowing for improved treatment adherence, reduced rescue inhaler usage and hospitalizations, increased patient satisfaction and asthma control.

Biased agonism at chemokine receptors

In the human chemokine system, interactions between the approximately 50 known endogenous chemokine ligands and 20 known chemokine receptors (CKRs) regulate a wide range of cellular functions and biological processes including immune cell activation and homeostasis, development, angiogenesis, and neuromodulation. CKRs are a family of G protein-coupled receptors (GPCR), which represent the most common and versatile class of receptors in the human genome and the targets of approximately one third of all Food and Drug Administration-approved drugs. Chemokines and CKRs bind with significant promiscuity, as most CKRs can be activated by multiple chemokines and most chemokines can activate multiple CKRs. While these ligand-receptor interactions were previously regarded as redundant, it is now appreciated that many chemokine:CKR interactions display biased agonism, the phenomenon in which different ligands binding to the same receptor signal through different pathways with different efficacies, leading to distinct biological effects. Notably, these biased responses can be modulated through changes in ligand, receptor, and or the specific cellular context (system). In this review, we explore the biochemical mechanisms, functional consequences, and therapeutic potential of biased agonism in the chemokine system. An enhanced understanding of biased agonism in the chemokine system may prove transformative in the understanding of the mechanisms and consequences of biased signaling across all GPCR subtypes and aid in the development of biased pharmaceuticals with increased therapeutic efficacy and safer side effect profiles.

Dexamethasone attenuates inflammatory-mediated suppression of β2-adrenoceptor expression in rat primary mixed glia

β₂-adrenoceptors are G-protein coupled receptors expressed on both astrocytes and microglia that play a key role in mediating the anti-inflammatory actions of noradrenaline in the CNS. Here the effect of an inflammatory stimulus (LPS + IFN-γ) was examined on glial β₂-adrenoceptor expression and function. Exposure of glia to LPS + IFN-γ decreased β₂-adrenoceptor mRNA and agonist-stimulated production of the intracellular second messenger cAMP. Pre-treatment with the synthetic glucocorticoid and potent anti-inflammatory agent dexamethasone prevented the LPS + IFN-γ-induced suppression of β₂-adrenoceptor mRNA expression. These results raise the possibility that inflammation-mediated β₂-adrenoceptor downregulation in glia may dampen the innate anti-inflammatory properties of noradrenaline in the CNS.

Pathological cardiac hypertrophy: the synergy of adenylyl cyclases inhibition in cardiac and immune cells during chronic catecholamine stress

Response to stressors in our environment and daily lives is an adaptation conserved through evolution as it is beneficial in enhancing the survival and continuity of humans. Although stressors have evolved, the drastic physiological response they elicit still remains unchanged. The chronic secretion and circulation of catecholamines to produce physical responses when they are not required may result in pathological consequences which affect cardiac function drastically. This review seeks to point out the probable implication of chronic stress in inducing an inflammation disorder in the heart. We discussed the likely synergy of a G protein-independent stimuli signaling via β₂-adrenergic receptors in both cardiomyocytes and immune cells during chronic catecholamine stress. To explain this synergy, we hypothesized the possibility of adenylyl cyclases having a regulatory effect on G protein-coupled receptor kinases. This was based on the negative correlations they exhibit during normal cardiac function and heart failures. As such, the downregulation of adenylyl cyclases in cardiomyocytes and immune cells during chronic catecholamine stress enhances the expressions of G protein-coupled receptor kinases. In addition, we explain the maladaptive roles played by G protein-coupled receptor kinase and extracellular signal-regulated kinase in the synergistic cascade that pathologically remodels the heart. Finally, we highlighted the therapeutic potentials of an adenylyl cyclases stimulator to attenuate pathological cardiac hypertrophy (PCH) and improve cardiac function in patients developing cardiac disorders due to chronic catecholamine stress.

NFkappaB is a Key Player in the Crosstalk between Inflammation and Cardiovascular Diseases

Inflammation is a key mechanism of cardiovascular diseases. It is an essential component of atherosclerosis and a significant risk factor for the development of cardiovascular events. In the crosstalk between inflammation and cardiovascular diseases, the transcription factor NFκB seems to be a key player since it is involved in the development and progression of both inflammation and cardiac and vascular damage. In this review, we deal with the recent findings of the role of inflammation in cardiac diseases, focusing, in particular, on NFκB as a functional link. We describe strategies for the therapeutic targeting of NFκB as a potential strategy for the failing heart.

Pharmacogenetics of inhaled long-acting beta2-agonists in asthma: A systematic review

BACKGROUND

Long-acting beta2-agonists (LABA) are recommended in asthma therapy; however, not all asthma patients respond well to LABA. We performed a systematic review on genetic variants associated with LABA response in patients with asthma.

METHODS

Articles published until April 2017 were searched by two authors using PubMed and EMBASE. Pharmacogenetic studies in patients with asthma and LABA response as an outcome were included.

RESULTS

In total, 33 studies were included in this systematic review; eight focused on children (n = 6051). Nineteen studies were clinical trials, while 14 were observational studies. Studies used different outcomes to define LABA response, for example, lung function measurements (FEV₁ , PEF, MMEF, FVC), exacerbations, quality of life, and asthma symptoms. Most studies (n = 30) focused on the ADRB2 gene, encoding the beta2-adrenergic receptor. Thirty studies (n = 14 874) addressed ADRB2 rs1042713, 7 ADRB2 rs1042714 (n = 1629), and 3 ADRB2 rs1800888 (n = 1892). The association of ADRB2 rs1042713 and rs1800888 with LABA response heterogeneity was successfully replicated. Other variants were only studied in three studies but not replicated. One study focused on the ADCY9 gene. Five studies and a meta-analysis found an increased risk of exacerbations in pediatrics using LABA carrying one or two A alleles (OR 1.52 [1.17; 1.99]). These results were not confirmed in adults.

CONCLUSIONS

ADRB2 rs1042713 variant is most consistently associated with response to LABA in children but not adults. To assess the clinical value of ADRB2 rs1042713 in children with asthma using LABA, a randomized clinical trial with well-defined outcomes is needed.

Inhalational supplementation of metformin butyrate: A strategy for prevention and cure of various pulmonary disorders

The management of chronic lung diseases such as cancer, asthma, COPD and pulmonary hypertension remains unsatisfactory till date, and several strategies are being tried to control the same. Metformin, a popular anti-diabetic drug has shown promising effects in pre-clinical studies and has been subject to several trials in patients with debilitating pulmonary diseases. However, the clinical evidence for the use of metformin in these conditions is disappointing. Recent observations suggest that metformin use in diabetic patients is associated with an increase in butyrate-producing bacteria in the gut microbiome. Butyrate, similar to metformin, shows beneficial effects in pathological conditions found in pulmonary diseases. Further, the pharmacokinetic data of metformin suggests that metformin is predominantly concentrated in the gut, even after absorption. Butyrate, on the other hand, has a short half-life and thus oral supplementation of butyrate and metformin is unlikely to result in high concentrations of these drugs in the lung. In this paper, we review the pre-clinical studies of metformin and butyrate pertaining to pathologies commonly encountered in chronic lung diseases and underscore the need to administer these drugs directly to the lung via the inhalational route.

Reduced suppressive effect of β2-adrenoceptor agonist on fibrocyte function in severe asthma

Background

Patients with severe asthma have increased airway remodelling and elevated numbers of circulating fibrocytes with enhanced myofibroblastic differentiation capacity, despite being treated with high doses of corticosteroids, and long acting β₂-adrenergic receptor (AR) agonists (LABAs). We determined the effect of β₂-AR agonists, alone or in combination with corticosteroids, on fibrocyte function.

Methods

Non-adherent non-T cells from peripheral blood mononuclear cells isolated from healthy subjects and patients with non-severe or severe asthma were treated with the β₂-AR agonist, salmeterol, in the presence or absence of the corticosteroid dexamethasone. The number of fibrocytes (collagen I⁺/CD45⁺ cells) and differentiating fibrocytes (α-smooth muscle actin⁺ cells), and the expression of CC chemokine receptor 7 and of β₂-AR were determined using flow cytometry. The role of cyclic adenosine monophosphate (cAMP) was elucidated using the cAMP analogue 8-bromoadenosine 3′,5′-cyclic monophosphate (8-Br-cAMP) and the phosphodiesterase type IV (PDE4) inhibitor, rolipram.

Results

Salmeterol reduced the proliferation, myofibroblastic differentiation and CCR7 expression of fibrocytes from healthy subjects and non-severe asthma patients. Fibrocytes from severe asthma patients had a lower baseline surface β₂-AR expression and were relatively insensitive to salmeterol but not to 8-Br-cAMP or rolipram. Dexamethasone increased β₂-AR expression and enhanced the inhibitory effect of salmeterol on severe asthma fibrocyte differentiation.

Conclusions

Fibrocytes from patients with severe asthma are relatively insensitive to the inhibitory effects of salmeterol, an effect which is reversed by combination with corticosteroids.

Electronic supplementary material

The online version of this article (10.1186/s12931-017-0678-7) contains supplementary material, which is available to authorized users.

G-protein-coupled receptor kinase 2 terminates G-protein-coupled receptor function in steroid hormone 20-hydroxyecdysone signaling

G-protein-coupled receptors (GPCRs) transmit extracellular signals across the cell membrane. GPCR kinases (GRKs) desensitize GPCR signals in the cell membrane. However, the role and mechanism of GRKs in the desensitization of steroid hormone signaling are unclear. In this study, we propose that GRK2 is phosphorylated by protein kinase C (PKC) in response to induction by the steroid hormone 20-hydroxyecdysone (20E), which determines its translocation to the cell membrane of the lepidopteran Helicoverpa armigera. GRK2 protein expression is increased during the metamorphic stage because of induction by 20E. Knockdown of GRK2 in larvae causes accelerated pupation, an increase in 20E-response gene expression, and advanced apoptosis and metamorphosis. 20E induces translocation of GRK2 from the cytoplasm to the cell membrane via steroid hormone ecdysone-responsive GPCR (ErGPCR-2). GRK2 is phosphorylated by PKC on serine 680 after induction by 20E, which leads to the translocation of GRK2 to the cell membrane. GRK2 interacts with ErGPCR-2. These data indicate that GRK2 terminates the ErGPCR-2 function in 20E signaling in the cell membrane by a negative feedback mechanism.

Defective Resensitization in Human Airway Smooth Muscle Cells Evokes β-Adrenergic Receptor Dysfunction in Severe Asthma

β₂-adrenergic receptor (β₂AR) agonists (β₂-agonist) are the most commonly used therapy for acute relief in asthma, but chronic use of these bronchodilators paradoxically exacerbates airway hyper-responsiveness. Activation of βARs by β-agonist leads to desensitization (inactivation) by phosphorylation through G-protein coupled receptor kinases (GRKs) which mediate β-arrestin binding and βAR internalization. Resensitization occurs by dephosphorylation of the endosomal βARs which recycle back to the plasma membrane as agonist-ready receptors. To determine whether the loss in β-agonist response in asthma is due to altered βAR desensitization and/or resensitization, we used primary human airway smooth muscle cells (HASMCs) isolated from the lungs of non-asthmatic and fatal-asthmatic subjects. Asthmatic HASMCs have diminished adenylyl cyclase activity and cAMP response to β-agonist as compared to non-asthmatic HASMCs. Confocal microscopy showed significant accumulation of phosphorylated β₂ARs in asthmatic HASMCs. Systematic analysis of desensitization components including GRKs and β-arrestin showed no appreciable differences between asthmatic and non-asthmatic HASMCs. However, asthmatic HASMC showed significant increase in PI3Kγ activity and was associated with reduction in PP2A activity. Since reduction in PP2A activity could alter receptor resensitization, endosomal fractions were isolated to assess the agonist ready β₂ARs as a measure of resensitization. Despite significant accumulation of β₂ARs in the endosomes of asthmatic HASMCs, endosomal β₂ARs cannot robustly activate adenylyl cyclase. Furthermore, endosomes from asthmatic HASMCs are associated with significant increase in PI3Kγ and reduced PP2A activity that inhibits β₂AR resensitization. Our study shows that resensitization, a process considered to be a homeostasis maintaining passive process is inhibited in asthmatic HASMCs contributing to β₂AR dysfunction which may underlie asthma pathophysiology and loss in asthma control.

Targeting α- and β-Adrenergic Receptors Differentially Shifts Th1, Th2, and Inflammatory Cytokine Profiles in Immune Organs to Attenuate Adjuvant Arthritis

The sympathetic nervous system (SNS) regulates host defense responses and restores homeostasis. SNS-immune regulation is altered in rheumatoid arthritis (RA) and rodent models of RA, characterized by nerve remodeling in immune organs and defective adrenergic receptor (AR) signaling to immune cell targets. The SNS typically promotes or suppresses inflammation via α- and β₂-AR activation, respectively, and indirectly drives humoral immunity by blocking Th1 cytokine secretion. Here, we investigate how β₂-AR stimulation and/or α-AR blockade at disease onset affects disease pathology and cytokine profiles in relevant immune organs from male Lewis rats with adjuvant-induced arthritis (AA). Rats challenged to induce AA were treated with terbutaline (TERB), a β₂-AR agonist (600 μg/kg/day) and/or phentolamine (PHEN), an α-AR antagonist (5.0 mg/kg/day) or vehicle from disease onset through severe disease. We report that in spleen, mesenteric (MLN) and draining lymph node (DLN) cells, TERB reduces proliferation, an effect independent of IL-2. TERB also fails to shift T helper (Th) cytokines from a Th1 to Th2 profile in spleen and MLN (no effect on IFN-γ) and DLN (greater IFN-γ) cells. In splenocytes, TERB, PHEN, and co-treatment (PT) promotes an anti-inflammatory profile (greater IL-10) and lowers TNF-α (PT only). In DLN cells, drug treatments do not affect inflammatory profiles, except PT, which raised IL-10. In MLN cells, TERB or PHEN lowers MLN cell secretion of TNF-α or IL-10, respectively. Collectively, our findings indicate disrupted β₂-AR, but not α-AR signaling in AA. Aberrant β₂-AR signaling consequently derails the sympathetic regulation of lymphocyte expansion, Th cell differentiation, and inflammation in the spleen, DLNs and MLs that is required for immune system homeostasis. Importantly, this study provides potential mechanisms through which reestablished balance between α- and β₂-AR function in the immune system ameliorates inflammation and joint destruction in AA.

Characterising the mechanism of airway smooth muscle β2 adrenoceptor desensitization by rhinovirus infected bronchial epithelial cells

Rhinovirus (RV) infections account for approximately two thirds of all virus-induced asthma exacerbations and often result in an impaired response to β2 agonist therapy. Using an in vitro model of RV infection, we investigated the mechanisms underlying RV-induced β2 adrenoceptor desensitization in primary human airway smooth muscle cells (ASMC). RV infection of primary human bronchial epithelial cells (HBEC) for 24 hours produced conditioned medium that caused β2 adrenoceptor desensitization on ASMCs without an effect on ASMCs viability. Less than 3 kDa size fractionation together with trypsin digestion of RV-induced conditioned medium did not prevent β2 adrenoceptor desensitization, suggesting it could potentially be mediated by a small peptide or lipid. RV infection of BECs, ASMCs and fibroblasts produced prostaglandins, of which PGE2, PGF2α and PGI2 had the ability to cause β2 adrenoceptor desensitization on ASMCs. RV-induced conditioned medium from HBECs depleted of PGE2 did not prevent ASMC β2 adrenoceptor desensitization; however this medium induced PGE2 from ASMCs, suggesting that autocrine prostaglandin production may be responsible. Using inhibitors of cyclooxygenase and prostaglandin receptor antagonists, we found that β2 adrenoceptor desensitization was mediated through ASMC derived COX-2 induced prostaglandins. Since ASMC prostaglandin production is unlikely to be caused by RV-induced epithelial derived proteins or lipids we next investigated activation of toll-like receptors (TLR) by viral RNA. The combination of TLR agonists poly I:C and imiquimod induced PGE2 and β2 adrenoceptor desensitization on ASMC as did the RNA extracted from RV-induced conditioned medium. Viral RNA but not epithelial RNA caused β2 adrenoceptor desensitization confirming that viral RNA and not endogenous human RNA was responsible. It was deduced that the mechanism by which β2 adrenoceptor desensitization occurs was by pattern recognition receptor activation of COX-2 induced prostaglandins.

Future bronchodilator therapy: a bitter pill to swallow?

Maintenance of airway tone, prevention of airway obstruction, and acute relief from bronchospasm are key targets of asthma therapy. This role is currently performed by β-agonists. However, chronic use of β-agonists to treat asthma is associated with desensitization of β-agonist signaling and a resultant loss of bronchodilator effect, worsening of airway hyperreactivity, and increased incidence of asthma-related morbidity and mortality. There have been several attempts to identify novel non-β-agonist bronchodilators including ATP-sensitive potassium channel (K(ATP)) agonists such as cromakalim and its active enantiomer BRL-38227 and the cGMP activators atrial natriuretic peptide (ANP) and BAY 41-22722. However, these either have not made it to clinical trial, required high doses, had little effect in patients, or had a high incidence of side effects. Recent data suggests that a novel bronchodilator target exists, the bitter taste receptor TAS2R. Two recent studies [An SS, Wang WC, Koziol-White CJ, Ahn K, Lee DY, Kurten RC, Panettieri RA Jr, Liggett SB. Am J Physiol Lung Cell Mol Physiol 303: L304-L311, 2012; Pulkkinen V, Manson ML, Säfholm J, Adner M, Dahlén SE. Am J Physiol Lung Cell Mol Physiol. doi:10.1152/ajplung.00205.2012.] provide new understanding of the signaling pathways utilized by TAS2Rs to mediate their bronchodilatory effects and how TAS2R-mediated bronchodilation is affected by β-agonist signaling desensitization. As our understanding of TAS2Rs and their agonists increases, they move closer to a viable therapeutic option; however, further definition is still required and questions remain to be answered. This editorial focus discusses these studies within the context of existing literature and raises questions and challenges for the future development of bitter (better?) therapies for asthma.

Repeated immobilization stress disturbed steroidogenic machinery and stimulated the expression of cAMP signaling elements and adrenergic receptors in Leydig cells

This study was designed to evaluate the effect of acute (2 h daily) and repeated (2 h daily for 2 or 10 consecutive days) immobilization stress (IMO) on: 1) the steroidogenic machinery homeostasis; 2) cAMP signaling; and the expression of receptors for main markers of 3) adrenergic and 4) glucocorticoid signaling in Leydig cells of adult rats. The results showed that acute IMO inhibited steroidogenic machinery in Leydig cells by downregulation of Scarb1 (scavenger receptor class B), Cyp11a1 (cholesterol side-chain cleavage enzyme), Cyp17a1 (17α-hydroxylase/17,20 lyase), and Hsd17b3 (17β-hydroxysteroid dehydrogenase) expression. In addition to acute IMO effects, repeated IMO increased transcription of Star (steroidogenic acute regulatory protein) and Arr19 (androgen receptor corepressor 19 kDa) in Leydig cells. In the same cells, the transcription of adenylyl cyclases (Adcy7, Adcy9, Adcy10) and cAMP-specific phosphodiesterases (Pde4a, Pde4b, Pde4d, Pde7a, Pde8a) was stimulated, whereas the expression of the genes encoding protein kinase A subunits were unaffected. Ten times repeated IMO increased the levels of all adrenergic receptors and β-adrenergic receptor kinase (Adrbk1) in Leydig cells. The transcription analysis was supported by cAMP/testosterone production. In this signaling scenario, partial recovery of testosterone production in medium/content was detected. The physiological significance of the present results was proven by ex vivo application of epinephrine, which increased cAMP/testosterone production by Leydig cells from control rats in greater fashion than from stressed. IMO did not affect the expression of transcripts for Crhr1/Crhr2 (corticotropin releasing hormone receptors), Acthr (adrenocorticotropin releasing hormone receptor), Gr (glucocorticoid receptor), and Hsd11b1 [hydroxysteroid (11-β) dehydrogenase 1], while all types of IMO stimulated the expression of Hsd11b2, the unidirectional oxidase with high affinity to inactivate glucocorticoids. Thus, presented data provide new molecular/transcriptional base for "fight/adaptation" of Leydig cells and new insights into the role of cAMP, epinephrine, and glucocorticoid signaling in recovery of stress-impaired Leydig cell steroidogenesis.

Efficacy and safety of a fixed-dose combination of mometasone furoate and formoterol fumarate in subjects with moderate to very severe COPD: results from a 52-week Phase III trial

BACKGROUND

A clinical trial of mometasone furoate/formoterol fumarate (MF/F) administered via a metered-dose inhaler in subjects with moderate to very severe chronic obstructive pulmonary disease (COPD) investigated the efficacy and safety of a fixed-dose combination of MF/F.

METHODS

This multicenter, double-blind, placebo-controlled trial had a 26-week treatment period and a 26-week safety extension. Subjects (n = 1055; ≥40 years) were current or ex- smokers randomized to twice-daily treatment with inhaled MF/F 400/10 μg, MF/F 200/10 μg, MF 400 μg, F 10 μg, or placebo. The coprimary endpoints of the trial were mean changes from baseline in forced expiratory volume in 1 second (FEV(1)) over 0-12 hours (AUC(0-12) FEV(1)) with MF/F versus MF, and in morning predose FEV(1) with MF/F versus F. Key secondary endpoints were quality of life (Saint George's Respiratory Questionnaire [SGRQ]), symptom-free nights, and partly stable COPD at 26 weeks, as well as time to first COPD exacerbation.

RESULTS

Significant improvements in FEV(1) AUC(0-12) occurred at endpoint with MF/F 400/10 and MF/F 200/10 versus MF 400 (P ≤ 0.007). Significant bronchodilation occurred in 5 minutes with MF/F, and serial spirometry demonstrated sustained FEV(1) improvements with MF/F over the treatment period. Significant improvements in morning predose FEV(1) occurred with both MF/F doses, and these effects were further investigated by excluding results for subjects whose morning FEV(1) data were collected >2 days after the last dose of study treatment. Improvements in SGRQ total scores surpassed the minimum clinically important difference of at least 4 units with MF/F 400/10. MF/F 400/10 significantly reduced the time-to-first COPD exacerbation. Similar proportions of subjects in all five treatment groups reported treatment-emergent adverse events. Rates of pneumonia were low (≤1.0%) across treatment groups.

CONCLUSION

MF/F 400/10 μg twice daily was shown to be an effective therapy for patients with moderate to very severe COPD, and both MF/F 400/10 μg twice daily and MF/F 200/10 μg twice daily were well tolerated.

Efficacy and safety characteristics of mometasone furoate/formoterol fumarate fixed-dose combination in subjects with moderate to very severe COPD: findings from pooled analysis of two randomized, 52-week placebo-controlled trials

Background

The clinical efficacy and safety of a mometasone furoate/formoterol fumarate (MF/F) fixed-dose combination formulation administered via a metered-dose inhaler was investigated in patients with moderate to very severe chronic obstructive pulmonary disease (COPD).

Methods

Two 52-week, multicenter, double-blind, placebo-controlled trials with identical study designs were conducted in current or ex-smokers (aged ≥40 years), and pooled study results are presented herein. Subjects (n = 2251) were randomized to 26 weeks of twice-daily treatment with MF/F 400/10 μg, MF/F 200/10 μg, MF 400 μg, F 10 μg, or placebo. After the 26-week treatment period, placebo subjects completed the trial and 75% of subjects on active treatment entered a 26-week safety extension. Coprimary efficacy variables were mean changes in forced expiratory volume in one second (FEV₁), area under the curve from 0 to 12 hours postdose (AUC_{0–12 h}), and morning predose/trough FEV₁ from baseline to the week 13 endpoint. Key secondary efficacy variables were St George’s Respiratory Questionnaire scores, symptom-free nights, time-to-first exacerbation, and partly stable COPD at the week 26 endpoint.

Results

In the 26-week treatment period, significantly greater increases in FEV₁ AUC_{0–12 h} occurred with MF/F 400/10 versus MF 400 and placebo at the week 13 and week 26 endpoints (P ≤ 0.032). These increases were over three-fold greater with MF/F 400/10 than with MF 400. Also, significantly greater increases in morning predose/trough FEV₁ occurred with MF/F 400/10 versus F 10 and placebo at the week 13 endpoint (P < 0.05). The increase was four-fold greater with MF/F 400/10 than with F 10. All active treatment groups achieved minimum clinically important differences from baseline (>4 units) in St George’s Respiratory Questionnaire scores at week 26. Symptom-free nights increased by ≥14% in the MF/F 400/10, MF 400, and F 10 groups (P ≤ 0.033 versus placebo). The incidence of exacerbations was lower in the MF/F groups (≤33.3%) than it was in the MF, formoterol, and placebo groups (≥33.8%) over the 26-week treatment period. The incidence of adverse events was similar in the active-treated and placebo-treated subjects across 26 weeks of treatment. Over the 1-year study period, there were no notable differences in the incidence or types of adverse events between the MF/F 400/10 and MF/F 200/10 groups compared with the MF or formoterol groups. Differences in rates of individual treatment-emergent adverse events were <3% between treatment groups. Rates of pneumonia were low (≤2%) across all treatment groups.

Conclusion

Patients treated with MF/F demonstrated significant improvements in lung function, health status, and exacerbation rates. Although significant improvements were seen with both doses, a trend showing a dose-response effect was observed in the lung function measurements.

Function and mechanisms of TSLP/TSLPR complex in asthma and COPD

Thymic stromal lymphopoietin (TSLP) is a key pro-allergic cytokine that has recently been linked to chronic airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD). High levels of TSLP were detected in bronchial mucosa of asthma and COPD patients suggesting TSLP's biological role beyond a signature 'Th2-favoring' or 'pro-allergic cytokine'. Besides inflammatory cells, airway structural cells produce and are targets of TSLP suggesting a potential autocrine loop that may have a profound effect on local inflammatory response and airway remodelling. This review sums up diverse mechanisms that mediate TSLP/TSLP receptor-signalling network in chronic airway diseases.

Microglial GRK2: a novel regulator of transition from acute to chronic pain

Pain is a hallmark of tissue damage and inflammation promoting tissue protection and thereby contributing to repair. Therefore, transient acute pain is an important feature of the adaptive response to damage. However, in a significant number of cases, pain persists for months to years after the problem that originally caused the pain has resolved. Such chronic pain is maladaptive as it no longer serves a protective aim. Chronic pain is debilitating, both physiologically and psychologically, and treatments to provide relief from chronic pain are often ineffective. The neurobiological mechanisms underlying the transition from adaptive acute pain to maladaptive chronic pain are only partially understood. In this review, we will summarize recent evidence that a kinase known as G protein-coupled receptor kinase (GRK2) is a key regulator of the transition from acute to chronic inflammatory pain. Our recent studies have shown that mice with a reduction in the cellular level of GRK2 develop chronic hyperalgesia in response to inflammatory mediators that induce only transient hyperalgesia in WT mice. This finding is clinically relevant because rodent models of chronic pain are associated with reduced cellular levels of GRK2. We propose that GRK2 is a newly discovered major player in the regulation of chronic pain. The pathways regulated by this kinase may open up new avenues for development of treatment strategies that target the cause, and not the symptoms of chronic pain.

Biochemical basis of asthma therapy

Current therapy for asthma is highly effective. β(2)-Adrenergic receptor (β(2)AR) agonists are the most effective bronchodilators and relax airway smooth muscle cells through increased cAMP concentrations and directly opening large conductance Ca(2+) channels. β(2)AR may also activate alternative signaling pathways that may have detrimental effects in asthma. Glucocorticoids are the most effective anti-inflammatory treatments and switch off multiple activated inflammatory genes through recruitment of histone deacetylase-2, activating anti-inflammatory genes, and through increasing mRNA stability of inflammatory genes. There are beneficial molecular interactions between β(2)AR and glucocorticoid-activated pathways. Understanding these signaling pathways may lead to even more effective therapies in the future.

Inhibition of p38 MAPK-dependent bronchial contraction after ozone by corticosteroids

We determined the role of p38 mitogen-activated protein kinase (MAPK) in the increased airway smooth muscle (ASM) contractile responses following ozone and modulation by corticosteroids. Mice were exposed to air or ozone (3 ppm for 3 h) and isometric contractile responses of bronchial rings to acetylcholine (ACh) were measured using a myograph in the presence of p38 MAPK inhibitor, SB239063 (10⁻⁶ M) or dexamethasone (10⁻⁶ M). Because MAPK phosphatase (MKP)-1 is a negative regulator of p38 MAPK, we also studied these effects in MKP-1(-/-) mice. Bronchial rings from ozone-exposed wild-type and MKP-1(-/-) mice showed increased contractile responses, with a leftward shift of the dose-response curve in MKP-1(-/-) mice. SB239063 inhibited bronchial contraction equally in air- and ozone-exposed C57/BL6 and MKP-1(-/-) mice. Dexamethasone inhibited ACh-induced bronchial contraction in both air- and ozone-exposed C57/BL6 mice, but not in air- or ozone-exposed MKP-1(-/-) mice. ACh-stimulated p38 MAPK and heat shock protein (HSP)27 phosphorylation, as measured by Western blotting, and this effect was suppressed by SB239063 in C57/BL6 and MKP-1(-/-) mice, but not by dexamethasone in either air- or ozone-exposed MKP-1(-/-) mice. p38 MAPK plays a role in maximal ACh-induced isometric contractile responses and increased contractility induced by ozone. Dexamethasone inhibits ACh-induced ASM contraction through phosphorylation of p38 MAPK and HSP27.

G protein-coupled receptor kinase 2 plays a relevant role in insulin resistance and obesity

OBJECTIVE

Insulin resistance is associated with the pathogenesis of metabolic disorders as type 2 diabetes and obesity. Given the emerging role of signal transduction in these syndromes, we set out to explore the possible role that G protein-coupled receptor kinase 2 (GRK2), first identified as a G protein-coupled receptor regulator, could have as a modulator of insulin responses.

RESEARCH DESIGN AND METHODS

We analyzed the influence of GRK2 levels in insulin signaling in myoblasts and adipocytes with experimentally increased or silenced levels of GRK2, as well as in GRK2 hemizygous animals expressing 50% lower levels of this kinase in three different models of insulin resistance: tumor necrosis factor-α (TNF-α) infusion, aging, and high-fat diet (HFD). Glucose transport, whole-body glucose and insulin tolerance, the activation status of insulin pathway components, and the circulating levels of important mediators were measured. The development of obesity and adipocyte size with age and HFD was analyzed.

RESULTS

Altering GRK2 levels markedly modifies insulin-mediated signaling in cultured adipocytes and myocytes. GRK2 levels are increased by ∼2-fold in muscle and adipose tissue in the animal models tested, as well as in lymphocytes from metabolic syndrome patients. In contrast, hemizygous GRK2 mice show enhanced insulin sensitivity and do not develop insulin resistance by TNF-α, aging, or HFD. Furthermore, reduced GRK2 levels induce a lean phenotype and decrease age-related adiposity.

CONCLUSIONS

Overall, our data identify GRK2 as an important negative regulator of insulin effects, key to the etiopathogenesis of insulin resistance and obesity, which uncovers this protein as a potential therapeutic target in the treatment of these disorders.

Dynamic changes in lymphocyte GRK2 levels in cardiac transplant patients: a biomarker for left ventricular function

G protein-coupled receptor kinase 2 (GRK2), which is upregulated in the failing human myocardium, appears to have a role in heart failure (HF) pathogenesis. In peripheral lymphocytes, GRK2 expression has been shown to reflect myocardial levels. This study represents an attempt to define the role for GRK2 as a potential biomarker of left ventricular function in HF patients. We obtained blood from 24 HF patients before and after heart transplantation and followed them for up to 1 year, also recording hemodynamic data and histological results from endomyocardial biopsies. We determined blood GRK2 protein by Western blotting and enzyme-linked immunosorbent assay. GRK2 levels were obtained before transplant and at first posttransplant biopsy. GRK2 levels significantly declined after transplant and remained low over the course of the study period. After transplantation, we found that blood GRK2 significantly dropped and remained low consistent with improved cardiac function in the transplanted heart. Blood GRK2 has potential as a biomarker for myocardial function in end-stage HF.

Dual-specificity phosphatase 1 as a pharmacogenetic modifier of inhaled steroid response among asthmatic patients

BACKGROUND

Inhaled corticosteroids (ICSs) are considered first-line treatment for persistent asthma, yet there is significant variability in treatment response. Dual-specificity phosphatase 1 (DUSP1) appears to mediate the anti-inflammatory action of corticosteroids.

OBJECTIVE

We sought to determine whether variants in the DUSP1 gene are associated with clinical response to ICS treatment.

METHODS

Study participants with asthma were drawn from the following multiethnic cohorts: the Genetics of Asthma in Latino Americans (GALA) study; the Study of African Americans, Asthma, Genes & Environments (SAGE); and the Study of Asthma Phenotypes and Pharmacogenomic Interactions by Race-ethnicity (SAPPHIRE). We screened GALA study participants for genetic variants that modified the relationship between ICS use and bronchodilator response. We then replicated our findings in SAGE and SAPPHIRE participants. In a group of SAPPHIRE participants treated with ICSs for 6 weeks, we examined whether a DUSP1 polymorphism was associated with changes in FEV(1) and self-reported asthma control.

RESULTS

The DUSP1 polymorphisms rs881152 and rs34507926 localized to different haplotype blocks and appeared to significantly modify the relationship between ICS use and bronchodilator response among GALA study participants. This interaction was also seen for rs881152 among SAPPHIRE but not SAGE participants. Among the group of SAPPHIRE participants prospectively treated with ICSs for 6 weeks, rs881152 genotype was significantly associated with changes in self-reported asthma control but not FEV(1).

CONCLUSION

DUSP1 polymorphisms were associated with clinical response to ICS therapy and therefore might be useful in the future to identify asthmatic patients more likely to respond to this controller treatment.

Should treatments for asthma be aimed at the airway smooth muscle?

The airway smooth muscle (ASM) cell is an important part of the airway wall of asthma patients because of its increased contractile properties, which appear to be enhanced in this condition and which contribute to airflow obstruction and bronchial hyper-responsiveness. ASM cells are also abnormal in asthma with increased expression of certain chemokines, with increased proliferation rate, numbers and size. beta-adrenergic agonists and corticosteroids are the two most important treatments for asthma; other drugs used are leukotriene receptor antagonists and theophylline. Combination therapy of beta-adrenergic agonists and corticosteroids has become the treatment of choice for moderate-to-severe asthma. beta-adrenergic agonists cause relaxation of ASM cells, leading to a decrease in airflow obstruction of asthma and acute relief of symptoms. Corticosteroids also have direct effects on ASM cells. It is postulated that the effect of anti-inflammatory agents on ASM cells is the most important determinant of the therapeutic effects of these agents. Targeting the ASM cell in asthma could be the focus of therapies for asthma. Specific delivery of active agents to ASM cells may also be part of this strategy.

Seven transmembrane receptors as shapeshifting proteins: the impact of allosteric modulation and functional selectivity on new drug discovery

It is useful to consider seven transmembrane receptors (7TMRs) as disordered proteins able to allosterically respond to a number of binding partners. Considering 7TMRs as allosteric systems, affinity and efficacy can be thought of in terms of energy flow between a modulator, conduit (the receptor protein), and a number of guests. These guests can be other molecules, receptors, membrane-bound proteins, or signaling proteins in the cytosol. These vectorial flows of energy can yield standard canonical guest allostery (allosteric modification of drug effect), effects along the plane of the cell membrane (receptor oligomerization), or effects directed into the cytosol (differential signaling as functional selectivity). This review discusses these apparently diverse pharmacological effects in terms of molecular dynamics and protein ensemble theory, which tends to unify 7TMR behavior toward cells. Special consideration will be given to functional selectivity (biased agonism and biased antagonism) in terms of mechanism of action and potential therapeutic application. The explosion of technology that has enabled observation of diverse 7TMR behavior has also shown how drugs can have multiple (pluridimensional) efficacies and how this can cause paradoxical drug classification and nomenclatures.

Mechanism of glucocorticoid protection of airway smooth muscle from proasthmatic effects of long-acting beta2-adrenoceptor agonist exposure

BACKGROUND

Chronic use of long-acting beta2-adrenergic receptor agonists (LABAs), resulting in beta2-adrenergic receptor desensitization, has been associated with increased asthma morbidity. When LABAs are used in combination with inhaled glucocorticoids, however, asthma control is improved, raising the following question: Do glucocorticoids inhibit the proasthmatic mechanism that mediates altered contractility in LABA-exposed airway smooth muscle (ASM)?

OBJECTIVE

This study aimed to identify the potential protective role and mechanism of action of glucocorticoids in mitigating the effects of prolonged LABA exposure on ASM constrictor and relaxation responsiveness.

METHODS

Cultured human ASM cells and isolated rabbit ASM tissues were examined for induced changes in agonist-mediated cyclic adenosine monophosphate accumulation, constrictor and relaxation responsiveness, and expression of specific glucocorticoid-regulated molecules after 24-hour exposure to the LABA salmeterol in the absence and presence of dexamethasone.

RESULTS

Salmeterol-exposed ASM exhibited impaired cyclic adenosine monophosphate and relaxation responses to isoproterenol and increased acetylcholine-induced contractility. These proasthmatic effects of prolonged LABA exposure were attributed to upregulated phosphodiesterase 4 (PDE4) activity and were ablated by pretreatment with dexamethasone. Further studies demonstrated that (1) dexamethasone suppressed activation of the mitogen-activated protein kinases extracellular signal-regulated kinases 1 and 2 (ERK1/2), which upregulate PDE4 expression in salmeterol-exposed ASM; and (2) the inhibitory actions of dexamethasone on salmeterol-induced ERK1/2 activation and resultant PDE4-mediated changes in ASM responsiveness were prevented by gene silencing or pharmacologic inhibition of dexamethasone-induced expression of mitogen-activated protein kinase phosphatase 1, an endogenous deactivator of ERK1/2 signaling.

CONCLUSION

Glucocorticoids prevent the adverse proasthmatic effects of prolonged LABA exposure on airway responsiveness as a result of glucocorticoid-induced upregulation of mitogen-activated protein kinase phosphatase 1, which inhibits proasthmatic ERK1/2 signaling in the LABA-exposed ASM.

Budesonide prevents cytokine-induced decrease of the relaxant responses to formoterol and terbutaline, but not to salmeterol, in mouse trachea

During asthma exacerbations, increased airway inflammation may impair the effects of beta(2)-adrenoceptor (beta(2)AR) agonists. It is unclear whether this impairment is prevented by inhaled glucocorticoids (GCs). We have investigated the relaxation of carbachol-contracted mouse tracheal segments to the beta(2)AR agonists formoterol, terbutaline, and salmeterol. The segments were pre-exposed for 4 days to the proinflammatory cytokines tumor necrosis factor alpha (100 ng/ml) and interleukin-1beta (10 ng/ml) with or without the GC, budesonide (1 microM). Formoterol and terbutaline induced greater maximal relaxation (R(max)) than salmeterol. The cytokines decreased R(max) of all beta(2)AR agonists, whereas budesonide had no effect. However, after concomitant treatment with cytokines and budesonide, the R(max) values of formoterol and terbutaline were not impaired, whereas budesonide did not prevent the decrease in the R(max) of salmeterol. A similar pattern was observed for cAMP production by the agonists. In tracheal smooth muscle, beta(2)AR mRNA was not affected by the cytokines but increased with budesonide. However, the cytokines markedly increased cyclooxygenase (COX)-2 mRNA expression, which may lead to heterologous desensitization of beta(2)AR. It is noteworthy that the cytokine-induced increase of COX-2 was blocked by concomitant budesonide suggesting that heterologous desensitization of beta(2)AR by the cytokines may be prevented by budesonide treatment. Budesonide prevented cytokine-induced impairment of the tracheal relaxation and beta(2)AR/cAMP signaling for formoterol but not for salmeterol. This suggests that differences exist between formoterol and salmeterol in beta(2)AR coupling/activation and/or signal transduction upstream of cAMP. These results imply that maximal bronchodilator effects of formoterol, but not of salmeterol, are maintained by budesonide treatment during periods with increased inflammation, such as asthma exacerbations.

Role of CRF receptor signaling in stress vulnerability, anxiety, and depression

Markers of hyperactive central corticotropin releasing factor (CRF) systems and CRF-related single nucleotide polymorphisms (SNPs) have been identified in patients with anxiety and depressive disorders. Designing more effective antagonists may now be guided by data showing that small molecules bind to transmembrane domains. Specifically, CRF(1) receptor antagonists have been developed as novel anxiolytic and antidepressant treatments. Because CRF(1) receptors become rapidly desensitized by G protein-coupled receptor kinase (GRK) and beta-arrestin mechanisms in the presence of high agonist concentrations, neuronal hypersecretion of synaptic CRF alone may be insufficient to account for excessive central CRF neurotransmission in stress-induced affective pathophysiology. In addition to desensitizing receptor function, GRK phosphorylation and beta-arrestin binding can shift a G protein-coupled receptor (GPCR) to signal selectively via the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK-MAPK) or Akt pathways independent of G proteins. Also, Epac-dependent CRF(1) receptor signaling via the ERK-MAPK pathway has been found to potentiate brain-derived neurotrophic factor (BDNF)-stimulated TrkB signaling. Thus, genetic or acquired abnormalities in GRK and beta-arrestin function may be involved in the pathophysiology of stress-induced anxiety and depression.

Molecular mechanisms of combination therapy with inhaled corticosteroids and long-acting beta-agonists

The treatment of asthma relies on the use of the following two major drug classes: beta(2)-agonists, both short acting and long acting; and corticosteroids (CSs). Although the properties of each drug class are well described, their use in combination delivered either separately or through one device has provided some clear and important clinical advantages. The mechanisms underlying these interactions have emerged as novel and provocative. beta(2)-Agonists can stimulate the glucocorticoid receptor (GR) and promote its translocation to the nucleus, resulting in increased CS-mediated gene transcription. In structural airway cells, such as fibroblasts and smooth muscle, this gene transcription is associated with the formation of a complex between the GR and another transcription factor, CCAAT enhancer-binding protein (C/EBP)-alpha. Airway smooth muscle cells from persons with asthma are deficient in C/EBP-alpha, which may explain the finding that CSs do not inhibit the proliferation of these cells in vitro. Whether this deficiency can explain the increased bulk of muscle in the asthmatic airway remains to be established. beta(2)-Agonists can inhibit mast cell mediator release, but this response is susceptible to desensitization, a process that CSs can inhibit. CSs also can increase the transcription of the beta(2)-receptor gene in the lung and the nasal mucosa. These effects of CSs mitigate against the reduced transcription of beta(2)-receptors, which occurs as a consequence of long-term beta(2)-agonist administration. Delineation of the exact mechanisms underlying these effects will ensure rational, direct therapy.

Repeated bouts of moderate-intensity aerobic exercise reduce airway reactivity in a murine asthma model

We have reported that moderate-intensity aerobic exercise training attenuates airway inflammation in mice sensitized/challenged with ovalbumin (OVA). The current study determined the effects of repeated bouts of aerobic exercise at a moderate intensity on airway hyperresponsiveness (AHR) in these mice. Mice were sensitized/challenged with OVA or saline and exercised at a moderate intensity 3 times/week for 4 weeks. At protocol completion, mice were analyzed for changes in AHR via mechanical ventilation. Results show that exercise decreased total lung resistance 60% in OVA-treated mice as compared with controls; exercise also decreased airway smooth muscle (ASM) thickness. In contrast, exercise increased circulating epinephrine levels 3-fold in saline- and OVA-treated mice. Because epinephrine binds beta(2)-adrenergic receptors (AR), which facilitate bronchodilatation, the role of beta(2)-AR in exercise-mediated improvements in AHR was examined. Application of the beta(2)-AR antagonist butoxamine HCl blocked the effects of exercise on lung resistance in OVA-treated mice. In parallel, ASM cells were examined for changes in the protein expression of beta(2)-AR and G-protein receptor kinase-2 (GRK-2); GRK-2 promotes beta(2)-AR desensitization. Exercise had no effect on beta(2)-AR expression in ASM cells of OVA-treated mice; however, exercise decreased GRK-2 expression by 50% as compared with controls. Exercise also decreased prostaglandin E(2) (PGE(2)) production 5-fold, but had no effect on E prostanoid-1 (EP1) receptor expression within the lungs of OVA-treated mice; both PGE(2) and the EP1 receptor have been implicated in beta(2)-AR desensitization. Together, these data indicate that moderate-intensity aerobic exercise training attenuates AHR via a mechanism that involves beta(2)-AR.

Effects and mechanisms of total glucosides of paeony on synoviocytes activities in rat collagen-induced arthritis

The aim of the study was to investigate the effects of TGP, an active compound extracted from the roots of Paeonia lactiflora Pall, on the activities of synoviocytes in rats with collagen-induced arthritis (CIA) and its possible mechanisms. CIA was induced in male Sprague-Dawley (SD) rats immunized with chicken type II collagen (CII) in Freund's complete adjuvant (FCA). Synoviocytes proliferation was determined by 3-(4, 5-2dimethylthiazal-2yl) 2, 5-diphenyltetrazoliumbromide (MTT) assay. Tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1), prostaglandin E(2) (PGE(2)) and cyclic adenosine monophosphate (cAMP) levels in synoviocytes were measured by radioimmunoassay (RIA). E-prostanoid (EP)(2) and EP(4) receptors were analyzed by Western blot analysis. The results showed that TGP significantly inhibited the proliferation of synoviocytes, decreased the production of IL-1, TNF-alpha and PGE(2) and elevated the levels of cAMP. Further study showed that TGP could up-regulate the expression of EP(2) and EP(4). These results indicated that TGP might exert its anti-inflammatory effects through inhibiting the production of pro-inflammatory mediators in synoviocytes of CIA rats, which might be associated with its ability to regulate cAMP-dependent EP(2)/EP(4)-mediated pathway.

Budesonide/formoterol for maintenance and reliever therapy in the management of moderate to severe asthma

The Global Initiative for Asthma (GINA) guidelines aim at improving asthma control and preventing future risk. For patients with moderate to severe asthma an inhaled corticosteroid (ICS) or an ICS/long-acting beta2-agonist (LABA) combination with a short-acting beta2-agonist (SABA) as reliever is recommended. Despite the availability of effective maintenance therapies, a large proportion of patients still fail to achieve guideline-defined asthma control, and overuse of SABA reliever medication at the expense of ICS is commonly observed. New simplified treatment approaches may offer a solution and assist physicians to achieve overall asthma control. One such treatment approach, which is recommended in the GINA guidelines, is budesonide/formoterol for both maintenance and reliever therapy. This treatment strategy significantly reduces the rate of severe asthma exacerbations compared with ICS/LABA plus SABA and achieves equivalent daily symptom control compared with higher doses of ICS/LABA plus separate SABA for relief. These benefits are achieved at a lower overall steroid load, and budesonide/formoterol maintenance and reliever therapy is well tolerated in patients with moderate to severe asthma. This review discusses current asthma management in patients with moderate to severe disease and examines the evidence for alternative asthma management approaches.

Steroids completely reverse albuterol-induced beta(2)-adrenergic receptor tolerance in human small airways

BACKGROUND

Evidence suggests that chronic stimulation of beta(2)-adrenergic receptors (beta(2)-ARs) induces receptor tolerance that limits the efficacy of beta-agonists in the treatment of asthma. The precise mechanisms that induce beta(2)-AR tolerance remain unclear.

OBJECTIVE

We sought to determine whether steroids modulate albuterol-induced beta(2)-AR tolerance in human small airways.

METHODS

beta(2)-AR responsiveness to isoproterenol was characterized in human precision-cut lung slices (PCLSs) precontracted to carbachol after pretreatment with albuterol.

RESULTS

Incubation of PCLSs with albuterol for 3, 6, or 12 hours attenuated subsequent isoproterenol-induced relaxation in a dose- and time-dependent manner. A 40% decrease (P < .0001) in maximum relaxation and a 45% decrease (P = .0011) in airway sensitivity from control values occurred after the maximum time and concentration of albuterol incubation. Desensitization was not evident when airways were relaxed to forskolin. Dexamethasone pretreatment of PCLSs (1 hour) prevented albuterol-induced beta(2)-AR desensitization by increasing the maximum drug effect (P = .0023) and decreasing the log half-maximum effective concentration values (P < .0001) from that of albuterol alone. Albuterol (12-hour incubation) decreased the beta(2)-AR cell-surface number (P = .013), which was not significantly reversed by 1 hour of preincubation with dexamethasone.

CONCLUSION

These data suggest that beta(2)-AR desensitization occurs with prolonged treatment of human small airways with albuterol through mechanisms upstream of protein kinase A and that steroids prevent or reverse this desensitization. Clarifying the precise molecular mechanisms by which beta(2)-AR tolerance occurs might offer new therapeutic approaches to improve the efficacy of bronchodilators in asthma and chronic obstructive pulmonary disease.

Endogenous Gs-coupled receptors in smooth muscle exhibit differential susceptibility to GRK2/3-mediated desensitization

Although G protein-coupled receptor (GPCR) kinases (GRKs) have been shown to mediate desensitization of numerous GPCRs in studies using cellular expression systems, their function under physiological conditions is less well understood. In the current study, we employed various strategies to assess the effect of inhibiting endogenous GRK2/3 on signaling and function of endogenously expressed G s-coupled receptors in human airway smooth muscle (ASM) cells. GRK2/3 inhibition by expression of a Gbetagamma sequestrant, a GRK2/3 dominant-negative mutant, or siRNA-mediated knockdown increased intracellular cAMP accumulation mediated via beta-agonist stimulation of the beta-2-adrenergic receptor (beta 2AR). Conversely, neither 5'-( N-ethylcarboxamido)-adenosine (NECA; activating the A2b adenosine receptor) nor prostaglandin E2 (PGE 2; activating EP2 or EP4 receptors)-stimulated cAMP was significantly increased by GRK2/3 inhibition. Selective knockdown using siRNA suggested the majority of PGE 2-stimulated cAMP in ASM was mediated by the EP2 receptor. Although a minor role for EP3 receptors in influencing PGE 2-mediated cAMP was determined, the GRK2/3-resistant nature of EP2 receptor signaling in ASM was confirmed using the EP2-selective agonist butaprost. Somewhat surprisingly, GRK2/3 inhibition did not augment the inhibitory effect of the beta-agonist on mitogen-stimulated increases in ASM growth. These findings demonstrate that with respect to G s-coupled receptors in ASM, GRK2/3 selectively attenuates beta 2AR signaling, yet relief of GRK2/3-dependent beta 2AR desensitization does not influence at least one important physiological function of the receptor.

Beta-arrestins specifically constrain beta2-adrenergic receptor signaling and function in airway smooth muscle

Chronic use of inhaled beta-agonists by asthmatics is associated with a loss of bronchoprotective effect and deterioration of asthma control. Beta-agonist-promoted desensitization of airway smooth muscle beta-2-adrenergic receptors, mediated by G protein-coupled receptor kinases and arrestins, is presumed to underlie these effects, but such a mechanism has never been demonstrated. Using in vitro, ex vivo, and in vivo murine models, we demonstrate that beta-arrestin-2 gene ablation augments beta-agonist-mediated airway smooth muscle relaxation, while augmenting beta-agonist-stimulated cyclic adenosine monophosphate production. In cultures of human airway smooth muscle, small interfering RNA-mediated knockdown of arrestins also augments beta-agonist-stimulated cyclic adenosine monophosphate production. Interestingly, signaling and function mediated by m2/m3 muscarinic acetylcholine receptors or prostaglandin E(2) receptors were not affected by either beta-arrestin-2 knockout or arrestin knockdown. Thus, arrestins are selective regulators of beta-2-adrenergic receptor signaling and function in airway smooth muscle. These results and our previous findings, which demonstrate a role for arrestins in the development of allergic inflammation in the lung, identify arrestins as potentially important therapeutic targets for obstructive airway diseases.

Regulation of heterotrimeric G protein signaling in airway smooth muscle

Heterotrimeric G proteins transduce signals from G protein-coupled receptors to regulate numerous signaling events and functions in airway smooth muscle (ASM). In this article, we detail the function and regulation of heterotrimeric G protein signaling in ASM. We further discuss recent advances in the development of experimental tools in the study of G protein signaling, and speculate how these tools might be used in therapeutic strategies that seek to mitigate bronchospasm and airway remodeling that occur in obstructive airway disease.

IL-1beta, BK, and TGF-beta1 attenuate PGI2-mediated cAMP formation in human pulmonary artery smooth muscle cells by multiple mechanisms involving p38 MAP kinase and PKA

We have previously shown that interleukin (IL)-1beta, transforming growth factor (TGF)-beta1, or bradykinin (BK) impair cAMP generation in response to prostacyclin analogs in human pulmonary artery smooth muscle (PASM), suggesting that inflammation can impair the effects of prostacyclin analogs on PASM in pulmonary hypertension. Here we explored the biochemical mechanisms involved. We found that IL-1beta, BK, and TGF-beta1 reduced adenylyl cyclase isoform 1, 2, and 4 mRNA, increased Galphai protein levels, and reduced prostacyclin receptor (IP receptor) mRNA expression. In contrast, Galphas protein levels were unchanged. Protein kinase A (PKA) (H-89, KT-2750, PKIm) and p38 mitogen-activated protein (MAP) kinase (SB-202190) inhibitors attenuated these effects, but protein kinase C (bisindolylmaleide) or phosphoinositol 3-kinase (LY-294002) inhibitors did not. Fluorescent kemptide assay and Western blotting confirmed that PKA and p38 MAP kinase were activated by IL-1beta, BK, and TGF-beta1. These studies suggest that IL-1beta, BK, and TGF-beta1 impair IP receptor-mediated cAMP accumulation by multiple effects on different components of the signaling pathway and that these effects are PKA and p38 MAP kinase dependent.

Effects of crocin on reperfusion-induced oxidative/nitrative injury to cerebral microvessels after global cerebral ischemia

This paper studied the effects of crocin, a pharmacologically active component of Crocus sativus L., on ischemia/reperfusion (I/R) injury in mice cerebral microvessels. Transient global cerebral ischemia (20 min), followed by 24 h of reperfusion, significantly promoted the generation of nitric oxide (NO) and malondialdehyde (MDA) in cortical microvascular homogenates, as well as markedly reduced the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) and promoted the activity of nitric oxide synthase (NOs). Reperfusion for 24 h led to serous edema with substantial microvilli loss, vacuolation, membrane damage and mitochondrial injuries in cortical microvascular endothelial cells (CMEC). Furthermore, enhanced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and decreased expression of matrix metalloproteinase-9 (MMP-9) were detected in cortical microvessels after I (20 min)/R (24 h). Reperfusion for 24 h also induced membrane (functional) G protein-coupled receptor kinase 2 (GRK2) expression, while it reduced cytosol GRK2 expression. Pretreatment with crocin markedly inhibited oxidizing reactions and modulated the ultrastructure of CMEC in mice with 20 min of bilateral common carotid artery occlusion (BCCAO) followed by 24 h of reperfusion in vivo. Furthermore, crocin inhibited GRK2 translocation from the cytosol to the membrane and reduced ERK1/2 phosphorylation and MMP-9 expression in cortical microvessels. We propose that crocin protects the brain against excessive oxidative stress and constitutes a potential therapeutic candidate in transient global cerebral ischemia.

Glucocorticoids Alter the Balance Between Pro- and Anti-inflammatory Mediators in the Myocardium in a Porcine Model of Brain Death

BACKGROUND

Cardiac dysfunction after brain death (BD) limits donors for cardiac transplantation. Glucocorticoids ameliorate brain death-induced donor heart dysfunction. We hypothesized that glucocorticoid therapy alleviates myocardial depression through altering the balance between pro- and anti-inflammatory mediators via the nuclear factor-kappaB (NF-kappaB)/inhibitor of kappaB-alpha (IkappaBalpha) pathway and/or by preserving beta-adrenergic receptor (betaAR) signaling in the heart.

METHODS

Crossbred pigs (25 to 35 kg) were randomly assigned to the following groups (n = 5/treatment): sham (Group 1); BD (Group 2); and BD with glucocorticoids (30 mg/kg methylprednisolone), either 2 hours before (Group 3) or 1 hour after BD (Group 4). Tumor necrosis factor-alpha (TNF-alpha) levels were measured in plasma at baseline and 1 hour and 6 hours after BD. Protein levels were measured in left ventricular homogenates procured 6 hours after BD.

RESULTS

Pro-inflammatory proteins (TNF-alpha) and interleukin-6 were lower in Group 3 and Group 4 compared with Group 2 at 6 hours after BD (p < 0.01). Intracellular adhesion molecule-1 was also lower in Group 4 compared with Group 2 (p = 0.001). Interleukin-10, an anti-inflammatory mediator, was lower in Group 4 than in Group 2 (p < 0.001), but not different between Groups 2 and 3. At 6 hours after BD, neither NF-kappaB activity nor basal adenylate cyclase activity differed between Groups 3 and 4 compared with Group 2.

CONCLUSIONS

Glucocorticoids maintained myocardial function and shifted the balance of pro- and anti-inflammatory mediators after BD. The mechanisms by which glucocorticoids preserve myocardial function, however, do not appear to involve the NF-kappaB pathway or betaAR signaling.

Long-acting beta2-agonists in asthma: not so SMART?

Asthma is a worldwide chronic disorder that is characterised by airway inflammation and hyper-responsiveness, which results in intermittent airflow obstruction and subsequent perception of symptoms and exacerbations. Inhaled corticosteroids are a fundamental component in the prevention of the short- and long-term complications associated with inadequately controlled asthma. However, many individuals experience persistent symptoms and exacerbations despite receiving low-to-medium doses of an inhaled corticosteroid (400-800 microg/day of beclometasone or equivalent). In these symptomatic asthmatic patients, guidelines advocate the initiation of a long-acting beta2-adrenoceptor agonist (LABA) as additional second-line controller therapy. The recent SMART (Salmeterol Multi-centre Asthma Research Trial) study was designed to compare the effects of add-on salmeterol 42 microg (ex-actuator) twice daily with placebo over 28 weeks in a randomised, double-blind, parallel-group fashion, with the intention to enrol 60,000 asthmatic patients. However, the study was halted prematurely because preliminary data revealed an increased mortality associated with regular use of salmeterol. Moreover, concerning rates of respiratory-related deaths, asthma-related deaths and life-threatening events were observed among African Americans, who constituted up to 18% of the study population. This in turn prompted the US FDA to announce important safety information regarding inhalers containing LABAs and advise that new labelling be produced outlining the "small but significant risk in asthma-related deaths" associated with their regular use. This evidence-based review discusses the data from SMART and highlights potentially important drawbacks with regular use of LABAs in persistent asthma.

A Noninflammatory Interleukin-1β Fragment Stimulates Fetal Lung Fluid Absorption in Guinea Pigs

We have previously demonstrated that full-length interleukin (IL)-1beta can induce and stimulate lung fluid absorption in near-term guinea pig fetuses via stimulation of fetal cortisol synthesis and release. To develop a potentially clinically useful drug, we tested the hypothesis that maternal administration of a noninflammatory IL-1beta-fragment (IL-1beta(Fr)) induced cortisol synthesis and stimulated lung fluid absorption in preterm fetuses. IL-1beta(Fr) was administered s.c. daily to timed-pregnant guinea pigs for 3 days with and without simultaneous cortisol synthesis inhibition by metyrapone. Fetuses were obtained by abdominal hysterotomy at 61 and 68 days gestation and instilled with isosmolar 5% albumin into the lungs, and lung fluid absorption was measured over 1 h by mass balance. Lung fluid absorption was induced at 61 days and stimulated at 68 days gestation by IL-1beta(Fr), which both were attenuated by cortisol synthesis inhibition. Moreover, induction of labor by oxytocin stimulated lung fluid absorption at 61 days but had no stimulatory effect at 68 days gestation when given with the IL-1beta(Fr). Plasma adrenocorticotropin and cortisol concentrations were increased by IL-1beta(Fr) at 61 days gestation and remained high but unstimulated by IL-1beta(Fr) at 68 days gestation, and metyrapone always reduced cortisol concentrations. Prenatal lung fluid absorption, when present as well as IL-1beta(Fr)-induced, was always propranolol- and amiloride-sensitive, suggesting that beta-adrenoceptor stimulation and the epithelial Na(+) channel (ENaC) were critical for the induced/stimulated lung fluid absorption. ENaC expression was increased by IL-1beta(Fr) and attenuated by cortisol synthesis inhibition. Thus, our results suggest a potential clinical use of IL-1beta(Fr) therapeutically to induce lung fluid absorption in fetuses at risk of preterm delivery.

GRKs and arrestins: regulators of migration and inflammation

In the immune system, signaling by G protein-coupled receptors (GPCRs) is crucial for the activity of multiple mediators, including chemokines, leukotrienes, and neurotransmitters. GPCR kinases (GRKs) and arrestins control GPCR signaling by mediating desensitization and thus, regulating further signal propagation through G proteins. Recent evidence suggests that the GRK-arrestin desensitization machinery fulfills a vital role in regulating inflammatory processes. First, GRK/arrestin levels in immune cells are dynamically regulated in response to inflammation. Second, in animals with targeted deletion of GRKs or arrestins, the progression of various acute and chronic inflammatory disorders, including autoimmunity and allergy, is profoundly affected. Third, chemokine receptor signaling in vitro is known to be tightly regulated by the GRK/arrestin machinery, and even small changes in GRK/arrestin expression can have a marked effect on cellular responses to chemokines. This review integrates data about the role of GRKs and arrestins in inflammation, with results on the molecular mechanism of action of GRKs/arrestins, and describes the pivotal role of GRKs/arrestins in inflammatory processes, with a special emphasis on regulation of chemokine responsiveness.

Targeting G protein-coupled receptor signaling in asthma

The complex disease asthma, an obstructive lung disease in which excessive airway smooth muscle (ASM) contraction as well as increased ASM mass reduces airway lumen size and limits airflow, can be viewed as a consequence of aberrant airway G protein-coupled receptor (GPCR) function. The central role of GPCRs in determining airway resistance is underscored by the fact that almost every drug used in the treatment of asthma directly or indirectly targets either GPCR-ligand interaction, GPCR signaling, or processes that produce GPCR agonists. Although many airway cells contribute to the regulation of airway resistance and architecture, ASM properties and functions have the greatest impact on airway homeostasis. The theme of this review is that GPCR-mediated regulation of ASM tone and ASM growth is a major determinant of the acute and chronic features of asthma, and multiple strategies targeting GPCR signaling may be employed to prevent or manage these features.

Agonist-independent alteration in beta-adrenoceptor-G-protein-adenylate cyclase system in an equine model of recurrent airway obstruction

We examined the inhibitory sympathetic beta-adrenergic mechanisms in peripheral lung, bronchi and trachea of an equine model of recurrent airway obstruction (RAO), to support the hypothesis that the beta-adrenergic receptor dysfunction is not only restricted to cell surface receptor density but rather encompasses a mechanistic defect apart from the receptor, to the intracellular signaling components. The non-asthmatic lung possessed 3.2-fold more beta-adrenergic receptors than bronchi (496 +/- 19.4 vs. 155.1+/- 19.6 fmol/mg protein; P < 0.01) and 6.2-fold higher than in the trachea (79.8 +/- 12.6 fmol/mg protein; P < 0.001) (assessed by radioligand binding assays using (-)-[(125)I]-iodocyanopindolol, ICYP) and in all tissues a greater proportion of the beta(2)- than the beta(1)-subtype (75-80%). The receptor density (B(max)) in lung parenchyma and bronchial membranes was 33 and 42%, respectively, lower (P < 0.001) in RAO than in control animals, attributable to a decrease in the beta(2)-subtype. This receptor down-regulation was accompanied with an attenuated coupling efficiency of the receptor to the stimulatory G(S)-protein (P < 0.05 vs. control). Concomitantly, activation of adenylate cyclase evoked by isoproterenol was significantly reduced in lung and bronchial membranes of animals with RAO, whereas effects of 10 microM GTP, 10mM NaF, 10 microM forskolin and 10 mM Mn(2+) were not altered. There was no difference in beta-adrenergic receptor density, G(S)-protein or adenylate cyclase coupling in the trachea between asthmatic and control animals. In conclusion, in stable asthma the pulmonary beta-adrenergic receptor-G(S)-protein-adenylate cyclase system is impaired, thus the pathologic process involves all signaling components, and due to its close similarity, this animal model seems to serve as a suitable model, at least partly, of chronic asthmatic patients.