Mechanisms of action of glucocorticoids in asthma

Methylprednisolone, dexamethasone or hydrocortisone for acute severe pediatric asthma: does it matter?

OBJECTIVE

Various intravenous (IV) corticosteroids are available for acute severe asthma (ASA) treatment. The choice of IV corticosteroids varies broadly and depends on institution, country, or physician preferences. In this study, we compared the efficacy of IV methylprednisolone, hydrocortisone and dexamethasone in ASA treatment during pediatric intensive care unit (PICU) admission.

METHODS

The study was a prospective randomized clinical trial. We enrolled patients of 1-21 years after they were admitted to the PICU requiring continuous beta-2 agonist treatment. Patients were randomized into three groups: Group A: IV Methylprednisolone, Group B: IV Hydrocortisone and Group C: IV Dexamethasone. The primary outcomes measured were durations of beta-2 agonist continuous nebulization treatment. Secondary outcomes, included PICU and hospital length of stay (LOS), pediatric asthma severity score (PASS), need for mechanical ventilation and maximum dose of beta-2 agonist treatment.

RESULTS

61 patients were included in the analysis. 22 patients recruited in Group A, 20 in group B and 19 group C. Median durations of beta-2-agonist treatment were 23 h (QR 16-38) for methylprednisolone, 27 h (QR 16-40) for hydrocortisone, and 32 h (QR 16-48) for dexamethasone (p = 0.90). There was no difference in PICU LOS, hospital LOS, PASS score, B2 agonist maximum dose, or need for ventilation support.

CONCLUSIONS

The use of IV methylprednisolone, hydrocortisone, and dexamethasone have equivalent efficacy when used at the appropriate doses. Studies with larger cohorts are needed to compare the effectiveness of IV corticosteroids in the management of ASA in the PICU setting.

Intravenous methylprednisolone versus intravenous methylprednisolone combined with inhaled budesonide in acute severe pediatric asthma

INTRODUCTION

Corticosteroids are important part of acute severe asthma (ASA) management in pediatric intensive care units. Few studies look at the efficacy of inhaled corticosteroids (ICS) in critical care settings. We aimed to investigate the potential beneficial effects of ICS when added to intravenous corticosteroids in pediatric patients with ASA admitted to the pediatric intensive care unit (PICU).

METHODS

This was a randomized controlled trial involving pediatric patients aged 1-21 years admitted to PICU with ASA. Patients were randomized into 2 groups using block randomization. Patients in Group A received intravenous methylprednisolone (2 mg/kg/day) alone and patients in Group B received intravenous methylprednisolone (2 mg/kg/day) plus budesonide nebulization (0.5 mg every 12 h). Main outcomes were duration of continuous albuterol treatment, PICU and hospital length of stay (LOS), and need and duration of respiratory support. Kruskal-Wallis and Chi-square tests were used for statistical analysis, in which a p-value < 0.05 was considered statistically significant.

RESULTS

Duration of continuous albuterol treatment was not different between the 2 groups median/(QR), 30/(18-51) vs. 25/(14-49). (p = 0.38) PICU and hospital LOS between the 2 groups was similar, median/(QR), 44/(30-64) vs. 46/(30-62), (p = 0.75) and 78/(65-95) vs.72/(58-92), (p = 0.19). Number of patients requiring respiratory support was 22(58%) in Group A and 25(64%) in Group B (p = 0.19).

CONCLUSIONS

In critically ill children with ASA, intravenous methylprednisolone combined with inhaled budesonide did not shorten the duration of continuous albuterol inhalation treatment, the PICU and hospital LOS, and the need for respiratory support.

Implications of immune-inflammatory responses in smooth muscle dysfunction and disease

In the past few decades, solid evidence has been accumulated for the pivotal significance of immunoinflammatory processes in the initiation, progression, and exacerbation of many diseases and disorders. This groundbreaking view came from original works by Ross who first described that excessive inflammatory-fibroproliferative response to various forms of insult to the endothelium and smooth muscle of the artery wall is essential for the pathogenesis of atherosclerosis (Ross, Nature 1993; 362(6423): 801–9). It is now widely recognized that both innate and adaptive immune reactions are avidly involved in the inflammation-related remodeling of many tissues and organs. When this state persists, irreversible fibrogenic changes would occur often culminating in fatal insufficiencies of many vital parenchymal organs such as liver, lung, heart, kidney and intestines. Thus, inflammatory diseases are becoming the common life-threatening risk for and urgent concern about the public health in developed countries (Wynn et al., Nature Medicine 2012; 18(7): 1028–40). Considering this timeliness, we organized a special symposium entitled “Implications of immune/inflammatory responses in smooth muscle dysfunction and disease” in the 58th annual meeting of the Japan Society of Smooth Muscle Research. This symposium report will provide detailed synopses of topics presented in this symposium; (1) the role of inflammasome in atherosclerosis and abdominal aortic aneurysms by Fumitake Usui-Kawanishi and Masafumi Takahashi; (2) Mechanisms underlying the pathogenesis of hyper-contractility of bronchial smooth muscle in allergic asthma by Hiroyasu Sakai, Wataru Suto, Yuki Kai and Yoshihiko Chiba; (3) Vascular remodeling in pulmonary arterial hypertension by Keizo Hiraishi, Lin Hai Kurahara and Ryuji Inoue.

Appropriate use of oral corticosteroids for severe asthma

Severe asthma represents a significant burden of disease, particularly in high income nations; oral corticosteroids (OCS) remain an important part of the management toolkit for these patients. Corticosteroids are effective at targeting numerous elements of the type 2/eosinophilic inflammatory pathway and lead to both rapid reduction in eosinophilic inflammation and longer term reduction in airway hyper-responsiveness. Resistance or insensitivity to corticosteroids is a feature of severe asthma, with persistent type 2 inflammation often occurring despite regular use of OCS. OCS remain the only accepted, effective treatment for acute asthma, and also continue to play an important role in the long term management of severe asthma, in spite of their significant side effect profile. Even with the availability of the new biological therapies against IgE and interleukin-5, it is likely that a large proportion of patients will continue to require OCS to control their asthma. Future work should focus on optimising the balance between OCS efficacy and safety, and continued development of agents that allow reduction, or ideally discontinuation of their use, is needed.

Modulation of TNF-α, IL-1Ra and IFN-γ in equine whole blood culture by glucocorticoids

Glucocorticoids are important drugs in the treatment of many inflammatory, autoimmune and allergic diseases in humans and animals. We investigated the effects of hydrocortisone and dexamethasone on TNF-α, IL-1Ra and INF-γ release in stimulated whole blood cell culture from healthy horses. Whole blood cell cultures proved to be useful for the characterization of the anti-inflammatory properties of new drugs. Diluted equine whole blood was exposed to lipopolysaccharide (LPS) and PCPwL (a cocktail consisting of phythemagglutinin E, concanavalin A, pokeweed mitogen and lipopolysaccharide) in the presence or absence of hydrocortisone and dexamethasone (10^-12 - 10^-5 M). TNF-α and IL-1Ra (LPS) as well as IFN-γ (PCPwL) levels were measured in the supernatants using specific enzyme-linked immunosorbent assay (ELISA). The LPS-induced TNF-α and IL-1Ra as well as the PCPwL-induced IFN-γ levels were more potently suppressed by dexamethasone than by hydrocortisone in a concentration-dependent manner. Dexamethasone inhibited TNF-α, IL-1Ra and IFN-γ with the half maximal inhibition concentration (IC₅₀) values of 0.09 μM, 0.453 μM and 0.001 μM, respectively, whereas hydrocortisone inhibited these cytokines with lower IC₅₀ values of 1.45 μM, 2.96 μM and 0.09 μM, respectively. Our results suggest that the equine whole blood test system is useful and reliable to evaluate drug effects and immunological alterations and offers several advantages including simple and cheap performance in physiological and pathological conditions.

Patient profiles and clinical utility of mepolizumab in severe eosinophilic asthma

Mepolizumab (Nucala^®) is an effective and specific anti-eosinophil molecular therapy that has recently been approved as add-on therapy for the management of severe eosinophilic asthma by the US Food and Drug Administration (FDA), European Medicines Agency (EMA; European Union) and more recently National Institute for Health and Care Excellence (NICE; UK). It is one of several molecular therapies in development for this indication and is illustrative of the strategic trajectory for pharmaceutical drug development taken over the past decade in several disease areas. Molecular therapies offer the prospect of improved specificity and effectiveness of biological effect. However, this necessitates a clear understanding of the underlying mechanistic pathways underpinning pathological processes, to inform drug development that yields novel more efficacious treatment options with a better clinical profile than existing agents. For the first time, utilization of molecular therapies in clinical trials is providing a novel in vivo model to characterize the association between specific pathways and clinical disease expression. It is increasingly recognized that asthma exhibits both clinical and pathological heterogeneity. It follows that a one-size-fits-all approach will not be appropriate and cost-effectiveness may only be achieved by identifying responder subgroups. This so-called personalized approach to therapy is being supported by the parallel development of companion biomarkers for clinical application. In this review, the author summarizes the clinical studies, their interpretation and the lessons learnt with mepolizumab that have informed our understanding of the approach to personalized molecular therapy in asthma.

Eosinophil resistance to glucocorticoid-induced apoptosis is mediated by the transcription factor NFIL3

The mainstay of asthma therapy, glucocorticoids (GCs) exert their therapeutic effects through the inhibition of inflammatory signaling and induction of eosinophil apoptosis. However, laboratory and clinical observations of GC-resistant asthma suggest that GCs' effects on eosinophil viability may depend on the state of eosinophil activation. In the present study we demonstrate that eosinophils stimulated with IL-5 show impaired pro-apoptotic response to GCs. We sought to determine the contribution of GC-mediated transactivating (TA) and transrepressing (TR) pathways in modulation of activated eosinophils' response to GC by comparing their response to the selective GC receptor (GR) agonist Compound A (CpdA) devoid of TA activity to that upon treatment with Dexamethasone (Dex). IL-5-activated eosinophils showed contrasting responses to CpdA and Dex, as IL-5-treated eosinophils showed no increase in apoptosis compared to cells treated with Dex alone, while CpdA elicited an apoptotic response regardless of IL-5 stimulation. Proteomic analysis revealed that both Nuclear Factor IL-3 (NFIL3) and Map Kinase Phosphatase 1 (MKP1) were inducible by IL-5 and enhanced by Dex; however, CpdA had no effect on NFIL3 and MKP1 expression. We found that inhibiting NFIL3 with specific siRNA or by blocking the IL-5-inducible Pim-1 kinase abrogated the protective effect of IL-5 on Dex-induced apoptosis, indicating crosstalk between IL-5 anti-apoptotic pathways and GR-mediated TA signaling occurring via the NFIL3 molecule. Collectively, these results indicate that (1) GCs' TA pathway may support eosinophil viability in IL-5-stimulated cells through synergistic upregulation of NFIL3; and (2) functional inhibition of IL-5 signaling (anti-Pim1) or the use of selective GR agonists that don't upregulate NFIL3 may be effective strategies for the restoring pro-apoptotic effect of GCs on IL-5-activated eosinophils.

Targeting sphingosine-1-phosphate signaling in lung diseases

Sphingosine-1-phosphate (S1P), a simple, bioactive sphingolipid metabolite, plays a key role, both intracellularly and extracellularly, in various cellular processes such as proliferation, survival, migration, inflammation, angiogenesis, and endothelial barrier integrity. The cellular S1P level is low and is tightly regulated by its synthesis and degradation. Sphingosine Kinases (SphKs) 1 and 2, catalyze the ATP-dependent phosphorylation of sphingosine to S1P, while the degradation is mediated by the reversible dephosphorylation catalyzed by the S1P phosphatases and lipid phosphate phosphatases and the irreversible degradation to hexadecenal and ethanolamine phosphate by sphingosine-1-phosphate lyase (S1PL). As a ligand for specific G-protein-coupled receptors, S1P1-5, which are differentially expressed in different cell types, S1P generates downstream signals that play crucial role in developmental and disease related pathologies. In addition to acting extracellularly on receptors located on the plasma membrane, S1P can also act intracellularly, independently of S1P1-5, affecting calcium homeostasis and cell proliferation. The SphKs /S1P /S1PL metabolic pathway is implicated in numerous human pathologies including respiratory disorders, thereby raising the possibility that manipulating intracellular S1P levels could offer therapeutic potential in ameliorating lung diseases. This review focuses on the prospects of targeting S1P signaling and S1P metabolizing enzymes using small molecule inhibitors, receptor agonists, and antagonists in the treatment of lung diseases.

Cytokine-Induced Glucocorticoid Resistance from Eosinophil Activation: Protein Phosphatase 5 Modulation of Glucocorticoid Receptor Phosphorylation and Signaling

The mechanisms contributing to persistent eosinophil activation and poor eosinopenic response to glucocorticoids in severe asthma are poorly defined. We examined the effect of cytokines typically overexpressed in the asthmatic airways on glucocorticoid signaling in in vitro activated eosinophils. An annexin V assay used to measure eosinophil apoptosis showed that cytokine combinations of IL-2 plus IL-4 as well as TNF-α plus IFN-γ, or IL-3, GM-CSF, and IL-5 alone significantly diminished the proapoptotic response to dexamethasone. We found that IL-2 plus IL-4 resulted in impaired phosphorylation and function of the nuclear glucocorticoid receptor (GCR). Proteomic analysis of steroid sensitive and resistant eosinophils identified several differentially expressed proteins, namely protein phosphatase 5 (PP5), formyl peptide receptor 2, and annexin 1. Furthermore, increased phosphatase activity of PP5 correlated with impaired phosphorylation of the GCR. Importantly, suppression of PP5 expression with small interfering RNA restored proper phosphorylation and the proapoptotic function of the GCR. We also examined the effect of lipoxin A4 on PP5 activation by IL-2 plus IL-4. Similar to PP5 small interfering RNA inhibition, pretreatment of eosinophils with lipoxin A4 restored GCR phosphorylation and the proaptoptotic function of GCs. Taken together, our results showed 1) a critical role for PP5 in cytokine-induced resistance to GC-mediated eosinophil death, 2) supported the dependence of GCR phosphorylation on PP5 activity, and 3) revealed that PP5 is a target of the lipoxin A4-induced pathway countering cytokine-induced resistance to GCs in eosinophils.

Human eosinophils are direct targets to nanoparticles: Zinc oxide nanoparticles (ZnO) delay apoptosis and increase the production of the pro-inflammatory cytokines IL-1β and IL-8

Zinc oxide NPs (ZnO) have been recently proposed as novel candidates for the treatment of allergic inflammatory diseases. Paradoxically, recent data suggested that ZnO could cause eosinophilic airway inflammation in rodents. Despite the above observations, there are currently no studies reporting direct interaction between a given NP and human eosinophils themselves. In this study, freshly isolated human eosinophils were incubated with ZnO and several cellular functions were studied. We found that ZnO delay human eosinophil apoptosis, partially by inhibiting caspases and by preventing caspase-4 and Bcl-xL degradation. ZnO do not induce production of reactive oxygen species but increase de novo protein synthesis. In addition, ZnO were found to increase the production of the proinflammatory IL-1β and IL-8 cytokines. Using a pharmacological approach, we demonstrated that inhibition of caspase-1 reversed the ability of ZnO to induce IL-1β and IL-8 production, whereas inhibition of caspase-4 only reversed that of IL-8. Our results indicate the necessity of conducting studies to determine the potential of using NP as nanotherapies, particularly in diseases in which eosinophils may be involved. We conclude that, indeed, human eosinophils represent potential new direct targets to NPs, ZnO in the present case.

Steroids and Sepsis: Time for Another Reevaluation

Treatment of sepsis has changed little in the past few decades and the lack of improvement is reflected in the relatively steady mortality rate. Much of the initial disappointment surrounding many of the past multicentered clinical trials in sepsis centers on the use of short-term, high-dose steroids. While recent advances focusing on the interplay between inflammation and coagulation are expected to result in important new treatments in sepsis, rekindled enthusiasm for the role of supraphysiologic-dose steroids is adding to the excitement. Specifically, emerging evidence suggests that moderate-dose glucocorticoids may improve outcomes in septic shock patients, in part, by treating occult adrenal insufficiency. One preliminary study that has sparked considerable interest reported a 30% relative reduction in mortality in sepsis patients treated with modest doses of hydrocortisone for 1 week. It appears clear the role of adrenal insufficiency and steroids in septic shock is deserving of a reevaluation.

Plasma IL-12 levels are suppressed in vivo by stress and surgery through endogenous release of glucocorticoids and prostaglandins but not catecholamines or opioids

IL-12 is a prominent Th1 differentiator and leukocyte activator. Ample studies showed suppression of IL-12 production by numerous stress factors, including prostaglandins, catecholamines, glucocorticoids, and opioids, but did so in vitro and in the context of artificial leukocyte activation, not simulating the in vivo setting. In a recent study we reported in vivo suppression of plasma IL-12 levels by behavioral stress and surgery. The current study aims to elucidate neuroendocrine mechanisms underlying this phenomenon in naïve F344 rats. To this end, both adrenalectomy and administration of specific antagonists were used, targeting the aforementioned stress factors. The results indicated that corticosterone and prostaglandins are prominent mediators of the IL-12-suppressing effects of stress and surgery, apparently through directly suppressing leukocyte IL-12 production. Following surgery, endogenous prostaglandins exerted their effects mainly through elevating corticosterone levels. Importantly, stress-induced release of epinephrine or opioids had no impact on plasma IL-12 levels, while pharmacological administration of epinephrine reduced plasma IL-12 levels by elevating corticosterone levels. Last, a whole blood in vitro study indicated that prostaglandins and corticosterone, but not epinephrine, suppressed IL-12 production in non-stimulated leukocytes, and only corticosterone did so in the context of CpG-C-induced IL-12 production. Overall, the findings reiterate the notion that results from in vitro or pharmacological in vivo studies cannot indicate the effects of endogenously released stress hormones under stress/surgery conditions. Herein, corticosterone and prostaglandins, but not catecholamines or opioids, were key mediators of the suppressive effect of stress and surgery on in vivo plasma IL-12 levels in otherwise naïve animals.

Cytokine profiles, signalling pathways and effects of fluticasone propionate in respiratory syncytial virus-infected human foetal lung fibroblasts

To examine cytokine production in response to RSV infection, we assessed the levels of 29 cytokines released from RSV-infected human foetal lung fibroblasts. We also examined the relationships between the effects of fluticasone propionate and various signalling pathways in the cells. Twenty-four hours after infection (1MOI), RSV-infected cells released cytokines, for example proinflammatory cytokines (IL-1β, IL-6 and TNF-α), anti-inflammatory (IL-1ra), Th1 (IFN-γ, IFN-λ1a, IL-2 and IL-12), Th2 (IL-4, IL-5, IL-10 and IL-13), granulopoiesis-inducing (G-CSF and GM-CSF), eosinophil recruitment-inducing (eotaxin and RANTES) and neutrophil recruitment-inducing cytokines (IL-8, IP-10, MCP-1 and MIP-1α). Aberrant release of most was significantly suppressed by fluticasone propionate. Twelve hours after RSV infection, increased phosphorylation of Akt, p38 MAPK, ERK1/2 and IκB-α was noted. Fluticasone propionate suppressed the phosphorylation of Akt, p38 MAPK, and ERK1/2, but not IκB-α, in virus-infected cells. TLR-4 expression was unchanged in control and RSV-infected cells, and TLR-3 and RIG-I expression was not detected. The results indicate that RSV infection induces aberrant production and release of certain cytokines through these signalling pathways in human lung fibroblasts. Overproduction and imbalance of these cytokines may be associated with the pathophysiology of RSV-induced excessive and allergic inflammation.

Bilateral tension pneumothorax caused by an abrupt increase in airway pressure during cervical spine surgery in the prone position -A case report-

Elevated peak inspiratory airway pressure (PIP) can occur during general anesthesia and is usually easily rectified. In rare circumstances it can lead to potentially fatal conditions such as tension pneumothorax. We report on a 77-year-old male patient admitted for a cervical laminoplasty. The preoperative chest radiograph showed normal findings and there was no medical history of allergy or underlying airway inflammation. Anesthesia induction and maintenance progressed uneventfully. However, 5 minutes after prophylactic antibiotic administration, PIP suddenly increased and blood pressure dropped. The operation was abandoned and the patient was moved to a supine position to perform chest radiography. Cardiac arrest occurred, and cardiopulmonary resuscitation was performed. The radiograph showed bilateral tension pneumothorax. Needle aspiration was immediately performed, and chest tubes were inserted. Ventilation rapidly improved and the vital signs normalized. The patient was discharged without sequelae on postoperative day 36.

Review article: management of acute severe and near-fatal asthma

Despite a decline in the Australian overall asthma mortality, near-fatal/critical asthma continues to be a significant management issue for emergency physicians and intensivists. Near-fatal asthma is a unique subtype of asthma, with a variety of clinical presentations, requiring rapid and aggressive intervention. The pharmacological and non-pharmacological management of near-fatal asthma remains very complex. The present review discusses recent advances and evidence for current available strategies targeting this time critical emergency.

Effects of corticosteroids on osteopontin expression in a murine model of allergic asthma

BACKGROUND

Osteopontin (OPN) contributes to the development of T helper 1 (Th1)-mediated immunity and Th1-associated diseases. However, the role of OPN in bronchial asthma is unclear. Corticosteroids reduce airway inflammation, as reflected by the low eosinophil and T-cell counts, and the low level of cytokine expression. We investigated OPN production and the inhibitory effects of corticosteroids on OPN production in a murine model of allergic asthma.

METHODS

BALB/c mice were sensitized by intraperitoneal injections of ovalbumin (OVA) with alum. Some mice received daily injections of dexamethasone (DEX) or phosphate-buffered saline for 1 week. All OVA-challenged mice were exposed to aerosolized 1% OVA for 30 min an hour after these injections. After the OVA challenge, the mice were killed, and bronchoalveolar lavage (BAL) fluid and lung tissue were examined.

RESULTS

The levels of OPN protein in BAL fluid and OPN mRNA in lung tissue increased after OVA challenge. Most OPN-expressing cells were CD11c+ cells and some were T cells. DEX decreased the levels of OPN protein in the BAL fluid, and those of OPN mRNA and OPN protein in lung tissue.

CONCLUSIONS

OPN may play an important role in allergic bronchial asthma. Corticosteroids inhibit OPN production in mice with allergic asthma. The beneficial effect of corticosteroids in bronchial asthma is partly due to their inhibitory effects on OPN production.

RANTES in exhaled breath condensate of stable and unstable asthma patients

RANTES has been implicated in the allergic inflammation of asthma by promoting the migration and activation of the inflammatory cells, including eosinophils. The study was undertaken to evaluate RANTES levels in the exhaled breath condensate (EBC) of asthmatics with different degrees of asthma severity. EBC was collected from 33 patients with allergic asthma (11 with steroid-naïve mild asthma, 10 with ICS-treated, stable mild-to-moderate asthma, 12 with ICS-treated unstable, severe asthma) and seven healthy volunteers. In the three groups of asthmatics, RANTES concentrations in EBC were significantly higher compared with healthy volunteers. RANTES levels were significantly higher in patients with unstable asthma than in the two groups with stable disease. We observed statistically significant correlations between the concentrations of RANTES in EBC and F(ENO) in the three studied groups of asthmatics; notably, the correlation between the parameters described above was strong positive in the group of unstable and steroid-naïve stable asthmatics. We also discovered a significantly positive correlation between RANTES in EBC and the serum ECP or blood eosinophil count in the groups of asthmatics with severe, unstable asthma and between RANTES and serum ECP in the group of steroid-naïve stable asthmatics. Measurements of RANTES in EBC may provide another useful diagnostic tool for detecting and monitoring inflammation in patients with asthma.

Anti-eosinophilic effect of Lafoensia pacari in toxocariasis

We previously reported the anti-inflammatory activity of Lafoensia pacari extract in Toxocara canis infection, a model of systemic IL-5-dependent eosinophil migration. In the present study, we describe the kinetics of the anti-inflammatory activity of L. pacari extract and compare it with dexamethasone. T. canis-infected mice were submitted to different treatment protocols and the cells present in bronchoalveolar space and peritoneal cavity were collected at the end of each treatment period. The results showed that L. pacari extract effectively inhibited eosinophil migration only when the treatment was initiated before the peak of eosinophil migration (1st to 18th; 12th to 18th and 12th to 24th day post-infection). When eosinophil migration was established, administration of L. pacari extract had no effect on it (treatment 18th to 24th day post-infection). Dexamethasone was effective in inhibiting eosinophil migration in all periods studied. We suggest that L. pacari extract can potentially be a natural alternative treatment of eosinophilic diseases.

Effect of dexamethasone on voltage-gated Na+ channel in cultured human bronchial smooth muscle cells

Voltage-gated Na(+) channel (I(Na)) encoded by SCN9A mRNA is expressed in cultured human bronchial smooth muscle cells. We investigated the effects of dexamethasone on I(Na), by using whole-cell voltage clamp techniques, reverse transcriptase/polymerase chain reaction (RT-PCR), and quantitative real-time RT-PCR. Acute application of dexamethasone (10(-6) M) did not affect I(Na). However, the percentage of the cells with I(Na) was significantly less in cells pretreated with dexamethasone for 48 h, and the current-density of I(Na) adjusted by cell capacitance in cells with I(Na) was also decreased in cells treated with dexamethasone. RT-PCR analysis showed that alpha and beta subunits mRNA of I(Na) mainly consisted of SCN9A and SCN1beta, respectively. Treatment with dexamethasone for 24-48 h inhibited the expression of SCN9A mRNA. The inhibitory effect of dexamethasone was concentration-dependent, and was observed at a concentration higher than 0.1 nM. The effect of dexamethasone on SCN9A mRNA was not blocked by spironolactone, but inhibited by mifepristone. The inhibitory effects of dexamethasone on SCN9A mRNA could not be explained by the changes of the stabilization of mRNA measured by using actinomycin D. These results suggest that dexamethasone inhibited I(Na) encoded by SCN9A mRNA in cultured human bronchial smooth muscle cells by inhibiting the transcription via the glucocorticoid receptor.

Glucocorticoids ameliorate antigen-induced bronchial smooth muscle hyperresponsiveness by inhibiting upregulation of RhoA in rats

To determine the mechanism(s) of the inhibitory effect of glucocorticoids on airway hyperresponsiveness in allergic bronchial asthma, the effects of systemic treatment with glucocorticoids on bronchial smooth muscle hyperresponsiveness and RhoA upregulation were investigated in rats with allergic bronchial asthma. Rats were sensitized and repeatedly challenged with 2,4-dinitrophenylated Ascaris suum antigen. Animals were also treated with prednisolone or beclomethasone (each 10 mg/kg, i.p.) once a day during the antigen inhalation period. Repeated antigen inhalation caused a marked bronchial smooth muscle hyperresponsiveness to acetylcholine with an upregulation of RhoA. Augmented acetylcholine-induced activation of RhoA and phosphorylation of myosin light chain were observed in bronchial smooth muscles of the antigen-exposed animals. Systemic treatment with either glucocorticoid used inhibited the bronchial smooth muscle hypercontraction until the level of the sensitized control rats that received saline inhalation instead of antigen challenge. Interestingly, both glucocorticoids also inhibited the upregulation of RhoA and augmented acetylcholine-induced activation of RhoA and phosphorylation of myosin light chain. In conclusion, glucocorticoids ameliorated the augmented bronchial smooth muscle contraction by inhibiting upregulation of RhoA. These effects of glucocorticoids may account for, in part, their beneficial effects in the treatment of asthma.

Modulation of eosinophil generation and migration by Mangifera indica L. extract (Vimang)

The effects of Vimang, an aqueous extract of the stem bark of Mangifera indica L. (Anacardiaceae), on cell migration in an experimental model of asthma was investigated. In vivo treatment of Toxocara canis-infected BALB/c mice for 18 days with 50 mg/kg Vimang reduced eosinophil migration into the bronchoalveolar space and peritoneal cavity. Also, eosinophil generation in bone marrow and blood eosinophilia were inhibited in infected mice treated with Vimang. This reduction was associated with inhibition of IL-5 production in serum and eotaxin in lung homogenates. In all these cases the effects of Vimang were more selective than those observed with dexamethasone. Moreover, Vimang treatment is not toxic for the animals, as demonstrated by the normal body weight increase during infection. These data confirm the potent anti-inflammatory effect of Vimang and support its potential use as an alternative therapeutic drug to the treatment of eosinophilic disorders including those caused by nematodes and allergic diseases.

Effects of perioperative antiinflammatory and immunomodulating therapy on surgical wound healing

Patients with various rheumatologic and inflammatory disease states commonly require drugs known to decrease the inflammatory or autoimmune response for adequate control of their condition. Such drugs include nonsteroidal antiinflammatory drugs (NSAIDs), cyclooxygenase (COX)-2 inhibitors, corticosteroids, disease-modifying antirheumatic drugs (DMARDs), and biologic response modifiers. These drugs affect inflammation and local immune responses, which are necessary for proper wound healing in the perioperative setting, thereby potentially resulting in undesirable postoperative complications. Such complications include wound dehiscence, infection, and impaired collagen synthesis. The end result is delayed healing of soft tissue and bone wounds. The current literature provides insight into the effect of some of these drugs on wound healing. For certain drugs, such as methotrexate, trials have been conducted in humans and direct us on what to do during the perioperative period. Whereas with other drugs, we must rely on either small-animal studies or extrapolation of data from human studies that did not specifically look at wound healing. Unfortunately, no clear consensus exists on the need and optimum time for withholding therapy before surgery. Likewise, clinicians are often uncertain of the appropriate time to resume therapy after the procedure. For those drugs with limited or no data in this setting, the use of pharmacokinetic properties and biologic effects of each drug should be considered individually. In some cases, discontinuation of therapy may be required up to 4 weeks before surgery because of the long half-lives of the drugs. In doing so, patients may experience an exacerbation or worsening of disease. Clinicians must carefully evaluate individual patient risk factors, disease severity, and the pharmacokinetics of available therapies when weighing the risks and benefits of discontinuing therapy in the perioperative setting.

Rapid inhibitory effect of glucocorticoids on airway smooth muscle contractions in guinea pigs

The common disease asthma is characterized by the obstruction, inflammation and increased sensitivity of the airways. Glucocorticoids (GCs) are one of the most potent anti-inflammatory agents available for treating allergic disease. In this study, we report that the GC budesonide (BUD) can rapidly inhibit the histamine-induced contractions of airway smooth muscle in a process mediated by non-genomic mechanisms. The tracheas of albino Hartley guinea pigs were used. We measured the effects of BUD on the increased isometric tension of trachea segment rings and the shrinking of single airway smooth muscle cells (ASMCs) induced by histamine. With the application of each reagent, the changes in the isometric tension of the segment rings upon maximum contraction and at four time points were recorded. We found that BUD significantly suppressed the increase in isometric tension induced by histamine in guinea pigs within 15 min. We also observed that BUD can reduce the histamine-induced shrinking of single ASMCs in an even shorter time. Mifepristone (RU486) and actidione did not depress the inhibitory effect of BUD. The results preclude action via genomic-mediated responses that usually take several hours to occur. We conclude therefore that GCs have a rapid non-genomic inhibitory effect on guinea pig airway smooth muscle contractions, and provide a new way to investigate this non-genomic mechanism. Further study can provide theoretical evidence for the clinical application of GCs in asthma and other allergic diseases.

Diagnostic and Therapeutic Value of Short-Term Corticosteroid Therapy in Exacerbation of Mustard Gas-Induced Chronic Bronchitis

Chronic bronchitis is the most frequent late respiratory disease among Iranians exposed to mustard gas during the Iraq-Iran war. The aim of this study was to investigate efficacy of oral and intravenous corticosteroid therapy in improving lung function in mustard gas induced chronic bronchitis patients. 65 mustard gas-exposed chronic bronchitis patients, who were not responsive to standard treatments in exacerbation occasions, were randomly divided into two groups: an intravenous group (39 patients) receiving 500 mg intravenous methylprednisolone daily, and an oral group (26 patients) receiving 1 mg/kg oral prednisolone daily. Corticosteroid was tapered over the study period in both groups. Spirometery was performed on admission and on day 8 of therapy for assessment of effectiveness of therapy. There was significant improvement in spirometery indexes of both groups in approximately half of the patients over the study period. Furthermore, there was no difference between the pulse corticosteroid versus oral corticosteroid therapy in these patients. Since short-term corticosteroid therapy has a significant effect on lung function of almost fifty percent of patients with mustard gas-induced chronic bronchitis in exacerbation occasions, we suggest a short-term bolus steroid treatment to triage the patients into responders and non-responders for subsequent treatment.

Liposomal methylprednisolone differentially regulates the expression of TNF and IL-10 in human alveolar macrophages

Glucocorticoids (GC) are frequently used for therapy of various inflammatory lung diseases by either systemic or inhalative application. Because the oral application often has various side effects and because the inhalative application is not as potent, new formulations of GCs are required. We evaluated the effect of a liposomal (Lip) formulation of methylprednisolone (MP) on the expression of lipopolysaccharide (LPS)-induced proinflammatory tumor necrosis factor (TNF) and antiinflammatory interleukin-10 (IL-10) in human alveolar macrophages (AM). AM were obtained from bronchoalveolar lavage fluids of patients with various inflammatory lung diseases and precultured 20 h+/-MP, either liposomal or free, and then stimulated with LPS. Cells were harvested for analysis of mRNA levels by real-time reverse transcriptase polymerase chain reaction (RT-PCR); supernatants were used to measure protein concentrations by ELISA. We confirm the suppression of LPS-induced TNF production by an average of factor 7 at the mRNA level and factor 3 at the protein level. On the other hand, we detected a strong increase of the IL-10 production by MP. At the mRNA level, liposomal MP alone led to an 18-fold increase, and the LPS-induced IL-10 mRNA was enhanced by factor 2. At the protein level, MP alone had no effect, but LPS-induced IL-10 was increased by factor 2.5. Our data show that liposomal MP can consistently induce IL-10 and reduce TNF when macrophages are exposed for a prolonged period of time. In all respects, liposomal MP had similar activities as free MP, but liposomes were selectively taken up by monocytes and macrophages and not by lymphocytes in blood and in the lung. This suggests that liposomal glucocorticoids when applied locally in the lung may act efficiently but with less side effects.

Allergens in the pathogenesis of asthma: potential role of anti-immunoglobulin E therapy

Evidence suggests that allergy is a significant triggering factor in asthma in children and adults alike. In immunoglobulin (Ig) E-mediated allergic reactions, sensitization occurs when allergen-specific B cells are stimulated and switched to IgE antibody production by interleukin (IL)-4 and IL-13 provided by helper T cells type 2 (Th2). The IgE antibodies act by arming cells bearing either the high-affinity (FcepsilonRI) or low-affinity (FcepsilonRII or CD23) receptor. The subsequent interaction of allergen with IgE-FcepsilonRI complexes on mast cells and basophils causes cross-linking of receptors that triggers the release of a variety of inflammatory mediators, cytokines and chemokines. Therefore, the ability to lower circulating free IgE levels is desirable because most individuals are exposed to multiple allergens to which they are sensitive at any given time. Omalizumab (formerly known as rhuMAb-E25) is a recently developed humanized monoclonal anti-IgE antibody directed at the FcepsilonRI binding domain of human IgE. It inhibits binding of IgE to mast cells without provoking mast cell activation. Preliminary clinical data from randomized controlled trials have shown that the addition of omalizumab to standard asthma therapy reduces asthma exacerbations and decreases inhaled corticosteroid and rescue medication use. The compound is also well tolerated. Omalizumab represents a novel therapeutic approach in the management of asthma.

Effects of corticosteroid on the expression of thymus and activation-regulated chemokine in a murine model of allergic asthma

BACKGROUND

Thymus and activation-regulated chemokine (TARC; CCL17) is a lymphocyte-directed CC chemokine that specifically attracts T-helper (Th) 2 cells positive for the CC chemokine receptor 4 (CCR4(+)). Corticosteroids reduce airway inflammation, as reflected by reduced numbers of eosinophils and T cells and reduced expression of cytokines. We investigated TARC production and the inhibitory effects of corticosteroids on TARC expression in a murine model of allergic asthma.

METHODS

BALB/c mice were sensitized by intraperitoneal injection of ovalbumin (OVA) with alum. Once daily for 1 week, mice received injections of dexamethasone or 0.2 ml saline (control), then 1 h later inhaled aerosolized 1% OVA for 30 min. Mice were killed 24 h after OVA challenge for bronchoalveolar lavage and lung tissue examination.

RESULTS

TARC was expressed mainly in the bronchial epithelial cells. Dexamethasone attenuated OVA-induced airway eosinophilia, lymphocyte infiltration, and airway hyperresponsiveness. Dexamethasone also decreased TARC production in the bronchoalveolar lavage fluid and decreased expression of TARC mRNA and TARC protein in lung tissue.

CONCLUSIONS

The corticosteroid dexamethasone inhibits TARC production in a murine model of allergic asthma in vivo. The beneficial effect of corticosteroids in bronchial asthma is due in part to their direct inhibitory effects on TARC production.

TBX21: a functional variant predicts improvement in asthma with the use of inhaled corticosteroids

TBX21 encodes for the transcription factor T-bet (T-box expressed in T cells), which influences naive T lymphocyte development and has been implicated in asthma pathogenesis. Specifically, the T-bet knockout mouse spontaneously develops airway hyperresponsiveness and other changes consistent with asthma. Because airway responsiveness is moderated by the use of inhaled corticosteroids in asthma, it is conceivable that genetic variation in TBX21 may alter asthma phenotypes in a treatment-specific fashion. Here we demonstrate that the nonsynonymous variation in TBX21 coding for replacement of histidine 33 with glutamine is associated with significant improvement in the PC(20) (a measure of airway responsiveness) of asthmatic children in a large clinical trial spanning 4 years. We note that this increase occurs only in the children randomized to inhaled corticosteroids and that it dramatically enhances the overall improvement in PC(20) associated with inhaled corticosteroid usage. The average PC(20) at trial end for subjects on inhaled corticosteroids possessing a variant allele was in the normal range for nonasthmatics. In cellular models, we show that the TBX21 variant increases T helper 1 and decreases T helper 2 cytokine expression comparably with wild type. TBX21 may thus be an important determinant pharmacogenetic response to the therapy of asthma with inhaled corticosteroids.

Strategies in the patient with compromised respiratory function

Respiratory diseases are commonly divided into restrictive or obstructive lung diseases. For anaesthesiological considerations restrictive lung diseases appear as a static condition with minimal short-term development. Overall, restrictive lung diseases don't lead to acute exacerbations due to the choice of anaesthetic techniques or the choice of anaesthesia-specific agents. Compared to restrictive lung diseases, obstructive lung diseases such as asthma or chronic obstructive lung diseases have a high prevalence and are one of the four most frequent causes of death. Obstructive lung diseases can be significantly influenced by the choice of anaesthetic technique and anaesthetic agent. Basically, the severity of the chronic obstructive pulmonary disease (COPD) and the degree of bronchial hyperreactivity will determine the perioperative anaesthetic risk. This risk has to be assessed by a thorough preoperative evaluation and will provide the rationale on which to decide the adequate anaesthetic technique. In particular, airway instrumentation can cause severe reflex bronchoconstriction. The use of regional anaesthesia alone or in combination with general anaesthesia can help to avoid airway irritation and even leads to reduced postoperative complications. Prophylactic anti-obstructive treatment, volatile anaesthetics, propofol, opioids, and an adequate choice of muscle relaxants minimize the anaesthetic risk when general anaesthesia is required. If intraoperative bronchospasm occurs, despite all precautions, deepening of anaesthesia, repeated administration of beta2-adrenergic agents and parasympatholytics, and a single systemic dose of corticosteroids are the main treatment options.

Budesonide/formoterol: in chronic obstructive pulmonary disease

Budesonide/formoterol is a fixed-dose combination of the corticosteroid budesonide and the long-acting beta2-agonist formoterol, and is inhaled via the Turbuhaler device. In two large, randomised, double-blind, 12-month studies, patients with severe chronic obstructive pulmonary disease (COPD) receiving budesonide/formoterol 320/9 microg twice daily had a significantly higher forced expiratory volume in 1 second (FEV1) and significantly higher morning and evening peak expiratory flow at trial endpoint than recipients of budesonide or placebo; FEV1 was significantly higher than with formoterol in the larger study. In both studies, the rate of COPD exacerbations and exacerbations requiring oral corticosteroids was significantly reduced with budesonide/formoterol versus formoterol and placebo. Moreover, the time to first exacerbation was significantly prolonged with budesonide/formoterol versus all other treatment arms in the larger study. At 12 months, significant improvements in health-related quality-of-life scores were seen with budesonide/formoterol versus placebo in both studies. The reduction in total and individual symptom scores was significantly greater with budesonide/formoterol than with budesonide or placebo in the smaller study. Budesonide/formoterol was generally well tolerated by patients with severe COPD. The tolerability profile of the combination was similar to that of the individual components with no increase in the incidence of adverse events.

Inhibition of chemokine production from human airway smooth muscle cells by fluticasone, budesonide and beclomethasone

Human airway smooth muscle cells (HASMC) contribute to the process of airway wall remodelling in asthma by virtue of their secretory functions. This study was performed to investigate the effectiveness of the commonly used steroids beclomethasone, budesonide and fluticasone in downregulating HASMC production of RANTES and IL-8. HASMC (n=5) were cultured from dissected bronchi using collagenase digestion. Confluent HASMC were exposed to TNFalpha and IL-1beta (10 ng/ml) for 24 h. All stimulations were set with and without pre-treatment with beclomethasone, budesonide or fluticasone for 2 h at concentrations of 10(-9)-10(-6)M. IL-8 and RANTES mRNA expression was assessed by RT-PCR and protein secretion was determined by ELISA. Pre-treatment with beclomethasone, budesonide or fluticasone reduced TNFalpha- and IL-1beta-stimulated IL-8 and RANTES release from HASMC in a dose dependent manner. However, beclomethasone was 22-28% less effective than fluticasone and budesonide in inhibiting chemokine production. TNFalpha- and IL-1beta-induced RANTES and IL-8 expression was reduced on the transcriptional level by pre-treatment with fluticasone and budesonide. The results suggest that the topical steroids fluticasone, budesonide and to a lesser extent beclomethasone may have beneficial effects on airway inflammation in asthma by reducing RANTES and IL-8-induced leukocyte infiltration into the airway wall.

Modulation of host defense by hydrocortisone in stress doses during endotoxemia

OBJECTIVE

To investigate the effects of low-dose hydrocortisone (HC) on neutrophil respiratory burst, phagocytosis, and elimination of E. coli from blood and tissue under endotoxemic and non-endotoxemic conditions. DESIGN. Randomized, controlled trial.

SETTING

Experimental laboratory, university hospital.

SUBJECTS

Forty-eight female chinchilla rabbits ( n=8 in six groups A-F).

INTERVENTIONS

In order to quantify the bacterial clearance process, defined numbers [10(8) colony forming units (CFU)] of Escherichia coli were injected intravenously into all anesthetized rabbits. Group A did not receive further intervention. Group B received bolus administration of HC 1.4 mg/kg and group C 14 mg/kg. Endotoxin (LPS, 40 microg/kg/h) was given to groups D, E, and F. Group E received additional bolus administration of HC 1.4 mg/kg and group F 14 mg/kg. All HC groups (B, C, E, and F) were continuously infused with HC 0.18 mg/kg/h.

MEASUREMENTS

Monitored parameters were neutrophil respiratory burst and phagocytosis activity, rates of bacterial elimination from the blood, arterial blood pressure, serum lactate and LPS concentrations, as well as nitrite and nitrate levels. Tissue samples of liver, kidney, spleen, and lung were collected for bacterial counts.

MAIN RESULTS

In controls HC significantly delayed elimination of injected E. coli from the blood (P<0.01). LPS also prolonged bacterial elimination but additional HC did not further delay removal of E. coli from the blood. Under endotoxemia HC depressed respiratory burst, whereas phagocytosis functions remained unaltered. Moreover, bacterial colonization of organs was reduced after HC in the LPS groups. Significance, however, was reached only in the liver (P<0.05). Due to HC, clearance from LPS (P<0.01) and lactate (P<0.05) were improved. Levels of nitrite and nitrate did not differ among the groups.

CONCLUSION

HC demonstrated immunomodulatory effects even in stress doses. In endotoxemic states use of low-dose HC seems to be favorable, although not in non-septic conditions.

TH2 Cytokine-enhanced and TGF-beta-enhanced vascular endothelial growth factor production by cultured human airway smooth muscle cells is attenuated by IFN-gamma and corticosteroids

BACKGROUND

T(H)2 and T(H)1 cytokines have opposite effects on many aspects of the inflammatory response.

METHODS

This study was designed to determine if cytokines possibly present in asthma can modulate airway smooth muscle cell (ASMC) production of vascular endothelial growth factor (VEGF) and thus contribute to altered airway vascularity. ASMC were incubated for 24 hours with various concentrations of T(H)2 cytokines (IL-4, IL-5, IL-10, and IL-13); transforming growth factor (TGF)-beta1, TGF-beta2, or TGF-beta3; and IL-1beta or TNF-alpha with or without IFN-gamma. Budesonide and exogenous prostaglandin (PG)E(2) were also evaluated. Postculture media were assayed for VEGF and PGE(2) by ELISA.

RESULTS

IL-4, IL-5, and IL-13 alone but not IL-10 enhanced VEGF production by ASMC in a concentration-dependent manner. IFN-gamma alone inhibited spontaneous VEGF release by ASMC and concentration-dependently attenuated IL-4-augmented, IL-5-augmented, or IL-13-augmented production of VEGF (P <.01). All three TGF-beta isoforms augmented VEGF production, which was reduced by IFN-gamma (P <.005). IL-1beta also increased VEGF production, but this was not affected by IFN-gamma (P >.05). TNF-alpha alone had little effect on VEGF release by ASMC. Production of VEGF stimulated by all cytokines was inhibited by budesonide. Exogenous PGE(2) increased VEGF release, but cytokine modulation of PGE(2) release did not always correlate with VEGF release.

CONCLUSIONS

T(H)2 cytokines and TGF-beta stimulate ASMC release of VEGF. This can be inhibited by IFN-gamma and glucocorticoids.

Morphologic changes in round window membrane after topical hydrocortisone and dexamethasone treatment

HYPOTHESIS

Are all glucocorticoids supposed to have the same effect on the round window membrane?

BACKGROUND

Interest in glucocorticoids for topical treatment of inner ear diseases is increasing. The safety of such treatment should therefore be an important consideration before clinical use.

METHODS

In this study the authors investigated the morphology of the round window membrane after topical instillation of dexamethasone or hydrocortisone into the middle ear. Twenty Sprague-Dawley rats were used. Five rats received 5 doses, and five rats 10 doses, of 1 microg (20 microl) dexamethasone in the right ear, and five others were given 5 doses, and five rats 10 doses, of 2% (20 microl) hydrocortisone solution, also in the right ear. Membrane morphology was studied in both light microscopy and transmission electron microscopy. The thickness of exposed membranes was measured and compared with that of control membranes.

RESULTS

Thickening and microscopically signs of inflammation were observed in hydrocortisone-exposed membranes but not in dexamethasone-exposed membranes, which did not differ morphologically from those in control ears.

CONCLUSION

Although hydrocortisone has anti-inflammatory properties, it seems to provoke inflammation in the round window membrane after topical instillation. Dexamethasone had no such effects, however.

[Airway remodeling in asthma: mechanisms and therapeutic perspectives]

Although asthma is classically defined as reversible airflow obstruction and often remits in younger subjects with milder disease, a proportion of asthmatics experience chronic symptoms, episodic exacerbations and persistent airway obstruction, despite the continuous use of beta 2-agonists, associated with high doses of inhaled/oral corticosteroids. These patients contribute to the majority of asthma costs through hospitalization, emergency visits, absence from work or school and use of medication. Although the mechanisms behind irreversible airflow obstruction in asthma are unclear, a prominent role has been attributed to persistent structural changes of the bronchial wall, defined as airway remodeling. Studies conducted on endobronchial biopsy samples have led to the histopathological characterization of these tissue alterations, which include chronic mucosal inflammation, extensive epithelial damage, collagen deposition, subepithelial fibrosis, increased mucous glands and airway smooth muscle hypertrophy and/or hyperplasia. Several factors, such as polypeptide growth factors and their receptors, matrix metalloproteases, intracellular molecules controlling cell death and survival, adhesion molecules and their ligands, as well a large variety of cytotoxic pro-inflammatory mediators are likely to contribute to the onset and maintenance of these tissue abnormalities. However, to date, the cellular and molecular events driving specifically these phenomena and allowing asthmatics with persistent airflow limitation to be distinguished from patients who normalize their bronchial obstruction upon adequate therapeutic management have not been identified yet. Accordingly, airway remodeling represents a major research challenge, particularly in view of the development of new therapeutic strategies specifically addressed at alleviating persistent bronchial obstruction in these otherwise intractable patients.

6. Asthma

The increasing incidence and prevalence of asthma in many parts of the world continue to make it a global health concern. The heterogeneous nature of the clinical manifestations and therapeutic responses of asthma in both adult and pediatric patients indicate that it may be more of a syndrome rather than a specific disease entity. Numerous triggering factors including viral infections, allergen and irritant exposure, and exercise, among others, complicate both the acute and chronic treatment of asthma. Therapeutic intervention has focused on the appreciation that airway obstruction in asthma is composed of both bronchial smooth muscle spasm and variable degrees of airway inflammation characterized by edema, mucus secretion, and the influx of a variety of inflammatory cells. The presence of only partial reversibility of airflow obstruction in some patients indicates that structural remodeling of the airways may also occur over time. Choosing appropriate medications depends on the disease severity (intermittent, mild persistent, moderate persistent, severe persistent), extent of reversibility, both acutely and chronically, patterns of disease activity (exacerbations related to viruses, allergens, exercise, etc), and the age of onset (infancy, childhood, adulthood).

Beclomethasone rapidly ablates allergen-induced beta 2-adrenoceptor pathway dysfunction in human isolated bronchi

Bronchial rings from nonatopic humans were passively sensitized with serum from allergic subjects. Allergen challenge significantly reduced the relaxant effect of salbutamol on carbachol-induced contractions, suggesting beta(2)-adrenoceptor (beta(2)-AR) pathway dysfunction. Incubation of challenged rings for 3 h with 3 x 10(-6) M beclomethasone dipropionate (BDP) restored the relaxant effect, suggesting reversal of beta(2)-AR pathway dysfunction. Incubation with the G(s)alpha protein-stimulating cholera toxin attenuated contractile responses to carbachol significantly less in challenged than in unchallenged rings. Treatment of challenged rings with BDP resulted in an inhibitory effect of cholera toxin that was similar to the effect in unchallenged rings. G(s)alpha protein expression was not significantly altered by BDP, suggesting that the activity of G(s)alpha protein was increased. Relaxation of challenged rings by forskolin was not significantly affected by BDP, suggesting that beta(2)-AR pathway dysfunction was proximal to the adenylyl cyclase. In conclusion, short-term (3-h) treatment with BDP after allergen challenge ablated beta(2)-AR pathway dysfunction by increasing the activity of the G(s)alpha protein in human isolated bronchi.

Refractory asthma

Treating patients with refractory asthma remains an ongoing challenge. Although most patients respond to large doses of systemic corticosteroid, the adverse effects associated with such a treatment limit its general use. Clinicians treating patients with refractory asthma must consider tapering systemic corticosteroid at every opportunity. Recent advances in the understanding of the pathogenesis of refractory asthma and corticosteroid resistance have fueled further study in the mechanisms of these processes and have prompted consideration of new treatment approaches. Unfortunately, most alternative approaches require more rigorous evidence to support their regular use.

Divergent effect of mometasone on human eosinophil and neutrophil apoptosis

Mometasone is a potent synthetic glucocorticoid, which is under development as an inhaled preparation for the treatment of asthma. Previous studies have suggested that glucocorticoids have direct effects on human eosinophil and neutrophil apoptosis. The present study was designed to characterize the effects of mometasone on constitutive apoptosis and cytokine-afforded survival in isolated human eosinophils and neutrophils. The isolated eosinophils or neutrophils were cultured in vitro, and apoptosis was assessed by flow cytometric analysis of relative DNA content, by annexin-V binding and morphological analysis. Mometasone enhanced constitutive human eosinophil apoptosis in a concentration-dependent manner. The maximal enhancement of eosinophil apoptosis was 2.1-fold with an EC(50) value of 5.63 +/- 2.33 nM. This enhancing effect was reversed by the glucocorticoid receptor antagonist, mifepristone. In the presence of added cytokines, mometasone reversed tumor necrosis factor -alpha-induced eosinophil survival but not that afforded by interleukin -5. In contrast, mometasone inhibited human neutrophil apoptosis in a concentration-dependent manner. The maximal inhibition of neutrophil apoptosis was 50% with an EC(50) value of 0.17 +/- 0.03 nM. The inhibitory effect was partly reversed by mifepristone. In the presence of added cytokines, mometasone further enhanced neutrophil survival induced by the granulocyte-macrophage colony-stimulating factor and leukotriene B(4). The present data suggests that mometasone has opposite effects on apoptosis of human eosinophils and neutrophils at clinically relevant drug concentrations via an effect on glucocorticoid receptor.

Modulation of TNF and GM-CSF release from dispersed human nasal polyp cells and human whole blood by inhibitors of different PDE isoenzymes and glucocorticoids

The aim of this study was to investigate the role of the inhibitors of different PDE isoenzymes (PDE 1-5) on the production of two pro-inflammatory cytokines - tumor necrosis factor alpha (TNF) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Two in vitro models were used to compare the antiinflammatory properties of PDE inhibitors with that of glucocorticoids. The effect on TNF release from diluted human blood following lipopolysaccharide (LPS from Salmonella abortus equi) stimulation as well as the GM-CSF and TNF release from human nasal polyp cells following allergic stimulation were investigated. Both models proofed to be well suited for the characterisation of the antiinflammatory properties of new chemical entities. In diluted human blood and dispersed human nasal polyp cells the induced TNF release was most potently suppressed by selective PDE4 inhibitors. Amrinone and milrinone, selective PDE3 inhibitors, suppressed TNF secretion to a lesser extent. The effects of theophylline (unspecific PDE inhibitor), vinpocetine (PDE1 inhibitor), EHNA (PDE2 inhibitor) and the PDE5 inhibitors zaprinast and E 4021 were weak. In human blood, the tested glucocorticoids beclomethasone, dexamethasone and fluticasone inhibited the LPS induced TNF release potently in a concentration dependent manner, whereas in dispersed human nasal polyp cells, the effect of the glucocorticoids on allergically induced TNF release, with the exception of dexamethasone, was much less pronounced. Glucocorticoids were the most potent inhibitors of GM-CSF release and the effect correlates well with the affinity to the glucocorticoid receptor. The selective PDE 4 inhibitors, and to a certain extent the PDE3 inhibitors amrinone and milrinone, reduced the GM-CSF release in a concentration dependent manner. In all investigations selective PDE4 inhibitors reduced TNF release to a much higher degree (4-10 fold) than GM-CSF release.

Efficacy of budesonide in inhaled corticosteroid-naive patients and patients with mild persistent asthma

BACKGROUND

Patients with mild intermittent or mild persistent asthma represent 70% of asthma sufferers. Inhaled corticosteroids (ICSs) are the mainstay of treatment for persistent asthma, although many of the early clinical studies of these drugs included only patients with moderate to severe asthma.

OBJECTIVE

This article reviews the literature on the efficacy of budesonide in the treatment of mild persistent asthma, including newly diagnosed ICS-naive patients.

METHODS

Published data were identified by a MEDLINE search of the English-language literature from 1992 to 2002 using the terms budesonide plus efficacy or safety, both with and without the termsfluticasone or beclomethasone. An AstraZeneca reference database was also used to identify publications from the same period. Controlled, randomized studies that included patients with mild persistent asthma and early-treatment intervention were selected for inclusion.

RESULTS

Inhaled budesonide has been used for almost 20 years in the treatment and control of moderate to severe asthma. Studies involving patients with mild persistent asthma have demonstrated significant improvements in peak expiratory flow (PEF) rates (P < 0.01) and forced expiratory volume in I second (P < 0.016) values for adult, adolescent, and pediatric patients treated with budesonide compared with placebo. Budesonide therapy is effective when given once or twice daily via dry powder inhaler or nebulizer, even at a low starting dose (200 microg/d). No significant adverse events have been reported with budesonide within the dose range used to treat mild persistent asthma (200 to 400 microg/d). Significant improvements in PEF rates (P < 0.01) and significant reductions in the risk of exacerbations and the number of days with poorly controlled asthma have been reported for ICS-naive patients treated with budesonide compared with placebo (both P < 0.001). In the primary care setting, mild persistent asthma may be undertreated. Patients with mild persistent asthma benefit significantly from early treatment with budesonide (P < 0.05).

CONCLUSIONS

Budesonide is effective and well tolerated in the treatment of mild persistent asthma in adults and children, including many patients whose primary care physicians do not think they require daily ICS treatment.

Anti-allergic therapies: effects on eosinophil progenitors

Marked eosinophilic infiltration is the typical inflammatory response associated with allergic inflammation. Previous research involving animal and human models has established a role for the eosinophil/basophil hematopoietic progenitor in a systemic process of allergic inflammation. In this article, we will review the evidence implicating eosinophil/basophil progenitors in this systemic response and will discuss the rationale for targeting this cell in the treatment of allergic disease. In this context, we discuss corticosteroid treatment of allergic diseases, such as asthma and its effects on hematopoietic mechanisms, the effects of therapies that inhibit the actions of cysteinyl leukotrienes, the effects of in vivo blockade of the eosinophil-active cytokine interleukin-5, and the effects of antihistamines on hematopoiesis. It is suggested that several anti-allergic therapies exert their beneficial effects on allergic inflammation by influencing eosinophil production systemically. Therefore, targeting the systemic hematopoietic response may provide additional, more beneficial, therapeutic effects.

Critical role of mitochondria, but not caspases, during glucocorticosteroid-induced human eosinophil apoptosis

Glucocorticosteroids are potent anti-inflammatory drugs used in the treatment of eosinophilic disorders. These molecules directly promote eosinophil apoptosis, yet the molecular mechanisms regulating this process remain ill-defined. We show here that stimulation of human peripheral blood eosinophils with dexamethasone induced DNA fragmentation, chromatin and cytoplasm condensation, and caspase-3 activation, as assessed by the proteolysis of its zymogen form and by the increase of caspase-3-like activity in eosinophil lysates. These phenomena were accompanied by a reduced uptake of the mitochondrial potential-sensitive marker DiOC(6)(3), suggestive of mitochondrial membrane permeabilization. Eosinophil incubation with the caspase-3 inhibitor, Z-Asp-Glu-Val-Asp-fluromethylketone, or with the broad spectrum caspase inhibitor, Z-Val-Ala-Asp-fluromethylketone, inhibited caspase-3-like activity generation but failed to modify dexamethasone-mediated loss in mitochondrial transmembrane potential and eosinophil apoptosis. In contrast, bongkrekic acid, a ligand of the mitochondrial permeability transition pore component, adenine nucleotide translocator, prevented both dexamethasone-induced mitochondrial disruption and apoptosis. We conclude that the mitochondrial permeability transition pore, rather than the caspase cascade, plays a critical role in the propagation of glucocorticosteroid-mediated apoptotic signals in human eosinophils.

Inhaled mometasone furoate: a review of its use in adults and adolescents with persistent asthma

Mometasone furoate is a corticosteroid with relatively high in vitro potency. Recent randomised, double-blind, multicentre trials have assessed the efficacy of mometasone furoate delivered by dry powder inhaler over 12 weeks in adults and adolescents with mild to severe persistent asthma. Mometasone furoate 200 microg twice daily or 400 microg once daily in the morning or 200 microg once daily in the evening improved lung function, asthma symptom scores and use of rescue medication to a significantly greater extent than placebo in patients who had previously received only short-acting inhaled beta2-adrenoceptor agonists alone as treatment in 3 trials (n = 195 to 306). In studies in 227 to 733 patients with mild to moderate asthma who were receiving ongoing treatment with inhaled corticosteroids prior to enrolment, mometasone furoate 100 to 400 microg twice daily was consistently better at improving the above indicators of asthma than placebo. Mometasone furoate 100 to 200 microg twice daily was as effective as beclomethasone dipropionate 200 microg twice daily or budesonide 400 microg twice daily and mometasone furoate 200 microg twice daily was as effective as fluticasone propionate 250 microg twice daily. Mometasone furoate 400 or 800 microg twice daily was also consistently more effective than placebo in reducing oral corticosteroid dosages and improving lung function and asthma symptoms in 132 patients with oral corticosteroid-dependent asthma. Once daily administration of mometasone furoate 400 microg appears to be as effective at improving indicators of asthma as twice daily administration of 200 microg. Patients receiving mometasone furoate < or =800 microg/day and recipients of placebo experienced a similar overall incidence of adverse events considered to be related to treatment. The most common of these events were oral candidiasis, headache, pharyngitis and dysphonia. Mometasone furoate 100 to 400 microg twice daily, beclomethasone dipropionate 200 microg twice daily, budesonide 400 microg twice daily or fluticasone propionate 250 microg twice daily were similarly tolerated.

CONCLUSION

Inhaled mometasone furoate is well tolerated, with minimal systemic activity and is equally effective when administered as a divided dose or as a single daily dose. Use of the drug can result in a decrease in requirements for oral corticosteroids in patients with oral corticosteroid-dependent asthma and is as effective as other inhaled corticosteroids currently used in the treatment of mild to moderate persistent asthma. Thus mometasone furoate is suitable for the control of mild to severe persistent asthma in adults or adolescents.

Pharmacogenetics of asthma

Recent advances in the extent of knowledge regarding interindividual genetic variation in drug treatment targets and drug metabolizing enzymes has resulted in studies designed to assess the contribution of genetic variability to treatment response in a range of diseases. This review describes the current state of knowledge of genetic variability in key airway targets important in the treatment of asthma. Whilst the genes coding for some key treatment targets contain little polymorphic variation (e.g. the muscarinic M2 and M3 receptors) other genes whose products are important targets in the treatment of asthma contain extensive genetic variation. The best examples of the latter are the beta2-adrenoceptor and the 5-lipoxygenase genes. Genetic variability in both of these genes may account in part for interindividual variability in treatment response. Finally, a number of key targets within the airways remain to be adequately screened for polymorphic variation.