Steroid-resistant asthma: evaluation and management

Glucocorticoid Insensitivity in Asthma: The Unique Role for Airway Smooth Muscle Cells

Although most patients with asthma symptoms are well controlled by inhaled glucocorticoids (GCs), a subgroup of patients suffering from severe asthma respond poorly to GC therapy. Such GC insensitivity (GCI) represents a profound challenge in managing patients with asthma. Even though GCI in patients with severe asthma has been investigated by several groups using immune cells (peripheral blood mononuclear cells and alveolar macrophages), uncertainty exists regarding the underlying molecular mechanisms in non-immune cells, such as airway smooth cells (ASM) cells. In asthma, ASM cells are among the targets of GC therapy and have emerged as key contributors not only to bronchoconstriction but also to airway inflammation and remodeling, as implied by experimental and clinical evidence. We here summarize the current understanding of the actions/signaling of GCs in asthma, and specifically, GC receptor (GR) “site-specific phosphorylation” and its role in regulating GC actions. We also review some common pitfalls associated with studies investigating GCI and the inflammatory mediators linked to asthma severity. Finally, we discuss and contrast potential molecular mechanisms underlying the impairment of GC actions in immune cells versus non-immune cells such as ASM cells.

Steroid-induced fibroblast growth factors drive an epithelial-mesenchymal inflammatory axis in severe asthma

Asthma and inflammatory airway diseases restrict airflow in the lung, compromising gas exchange and lung function. Inhaled corticosteroids (ICSs) can reduce inflammation, control symptoms, and improve lung function; however, a growing number of patients with severe asthma do not benefit from ICS. Using bronchial airway epithelial brushings from patients with severe asthma or primary human cells, we delineated a corticosteroid-driven fibroblast growth factor (FGF)-dependent inflammatory axis, with FGF-responsive fibroblasts promoting downstream granulocyte colony-stimulating factor (G-CSF) production, hyaluronan secretion, and neutrophilic inflammation. Allergen challenge studies in mice demonstrate that the ICS, fluticasone propionate, inhibited type 2-driven eosinophilia but induced a concomitant increase in FGFs, G-CSF, hyaluronan, and neutrophil infiltration. We developed a model of steroid-induced neutrophilic inflammation mediated, in part, by induction of an FGF-dependent epithelial-mesenchymal axis, which may explain why some individuals do not benefit from ICS. In further proof-of-concept experiments, we found that combination therapy with pan-FGF receptor inhibitors and corticosteroids prevented both eosinophilic and steroid-induced neutrophilic inflammation. Together, these results establish FGFs as therapeutic targets for severe asthma patients who do not benefit from ICS.

Ozone-Induced Oxidative Stress, Neutrophilic Airway Inflammation, and Glucocorticoid Resistance in Asthma

Despite recent advances in using biologicals that target Th2 pathways, glucocorticoids form the mainstay of asthma treatment. Asthma morbidity and mortality remain high due to the wide variability of treatment responsiveness and complex clinical phenotypes driven by distinct underlying mechanisms. Emerging evidence suggests that inhalation of the toxic air pollutant, ozone, worsens asthma by impairing glucocorticoid responsiveness. This review discusses the role of oxidative stress in glucocorticoid resistance in asthma. The underlying mechanisms point to a central role of oxidative stress pathways. The primary data source for this review consisted of peer-reviewed publications on the impact of ozone on airway inflammation and glucocorticoid responsiveness indexed in PubMed. Our main search strategy focused on cross-referencing "asthma and glucocorticoid resistance" against "ozone, oxidative stress, alarmins, innate lymphoid, NK and γδ T cells, dendritic cells and alveolar type II epithelial cells, glucocorticoid receptor and transcription factors". Recent work was placed in the context from articles in the last 10 years and older seminal research papers and comprehensive reviews. We excluded papers that did not focus on respiratory injury in the setting of oxidative stress. The pathways discussed here have however wide clinical implications to pathologies associated with inflammation and oxidative stress and in which glucocorticoid treatment is essential.

Questioning Cause and Effect: Children with Severe Asthma Exhibit High Levels of Inflammatory Biomarkers Including Beta-Hexosaminidase, but Low Levels of Vitamin A and Immunoglobulins

Asthma affects over 8% of the pediatric population in the United States, and Memphis, Tennessee has been labeled an asthma capital. Plasma samples were analyzed for biomarker profiles from 95 children with severe asthma and 47 age-matched, hospitalized nonasthmatic controls at Le Bonheur Children's Hospital in Memphis, where over 4000 asthmatics are cared for annually. Asthmatics exhibited significantly higher levels of periostin, surfactant protein D, receptor for advanced glycation end products and β-hexosaminidase compared to controls. Children with severe asthma had lower levels of IgG1, IgG2 and IgA, and higher levels of IgE compared to controls, and approximately half of asthmatics exhibited IgG1 levels that were below age-specific norms. Vitamin A levels, measured by the surrogate retinol-binding protein, were insufficient or deficient in most asthmatic children, and correlated positively with IgG1. Which came first, asthma status or low levels of vitamin A and immunoglobulins? It is likely that inflammatory disease and immunosuppressive drugs contributed to a reduction in vitamin A and immunoglobulin levels. However, a nonmutually exclusive hypothesis is that low dietary vitamin A caused reductions in immune function and rendered children vulnerable to respiratory disease and consequent asthma pathogenesis. Continued attention to nutrition in combination with the biomarker profile is recommended to prevent and treat asthma in vulnerable children.

Effects of genetic polymorphisms in Vitamin D metabolic pathway on Vitamin D level and asthma control in South Indian patients with bronchial asthma

Objectives:

The study was designed to evaluate the single-nucleotide polymorphisms (SNPs) of genes involved in Vitamin D actions (rs2228570) and metabolic pathways (rs2248137 and rs10766197) and their associations with serum 25-hydroxy Vitamin D (25(OH)D) level and asthma control in South Indian patients with bronchial asthma.

Materials and Methods:

One hundred and two patients of South Indian origin with bronchial asthma either naive to inhaled corticosteroids (ICSs) or not receiving ICS for ≥1 month were included and were treated with ICS (beclomethasone 200 μg twice daily) for 8 weeks. One hundred and one unrelated healthy South Indians were used as controls. Pulmonary function test and fractional exhaled nitric oxide were used to assess asthma control. Serum 25(OH)D levels (chemiluminescence immunoassay) and SNPs in Vitamin D pathway (real-time polymerase chain reaction) were assessed. The associations of SNPs and serum 25(OH)D with asthma control was determined using linear regression. All analyses were performed using SPSS (version 19) and “SNPStats.” P < 0.05 was considered as statistically significant.

Results:

Vitamin D receptor (VDR) polymorphism (rs2228570) was found to be protective against asthma (P = 0.022), while there were no significant associations between the other two SNPs and asthma. Similarly, poor correlation and insignificant associations between the SNPs and serum 25(OH)D levels were observed in both cases and controls. There were also insignificant associations between the SNPs and asthma control.

Conclusion:

VDR polymorphism (rs2228570) was found to be protective against asthma in South Indians, while other genes involved in the metabolic pathway of Vitamin D did not show associations with asthma.

Diagnosis of asthma - new theories

INTRODUCTION

Recent studies have shown a remarkably high frequency of poorly controlled asthma. Several reasons for this treatment failure have been discussed, however, the basic question of whether the diagnosis is always correct has not been considered. Follow-up studies have shown that in many patients asthma cannot be verified despite ongoing symptoms. Mechanisms other than bronchial obstruction may therefore be responsible. The current definition of asthma may also include symptoms that are related to mechanisms other than bronchial obstruction, the clinical hallmark of asthma.

AIM

Based on a review of the four cornerstones of asthma - inflammation, hyperresponsiveness, bronchial obstruction and symptoms - the aim was to present some new aspects and suggestions related to the diagnosis of adult non-allergic asthma.

CONCLUSION

Recent studies have indicated that "classic" asthma may sometimes be confused with asthma-like disorders such as airway sensory hyperreactivity, small airways disease, dysfunctional breathing, non-obstructive dyspnea, hyperventilation and vocal cord dysfunction. This confusion may be one explanation for the high proportion of misdiagnosis and treatment failure. The current diagnosis, focusing on bronchial obstruction, may be too "narrow". As there may be common mechanisms a broadening to include also non-obstructive disorders, forming an asthma syndrome, is suggested. Such broadening requires additional diagnostic steps, such as qualitative studies with analysis of reported symptoms, non-effort demanding methods for determining lung function, capsaicin test for revealing airway sensory hyperreactivity, careful evaluation of the therapeutic as well as diagnostic effect of corticosteroids and testing of suggested theories.

Diagnosis of asthma - a new approach

Current definition of asthma involves four cornerstones: inflammation, hyperresponsiveness, bronchoconstriction, and symptoms. In research, the symptoms have had the slightest attention. According to international guidelines, the asthma symptoms are episodic breathlessness, wheeze, cough, tightness of the chest, and shortness of breath. As there are several symptoms, a primary question is how they are related to bronchoconstriction, the main clinical feature of asthma. Symptoms and lung function tests are regularly used for the evaluation of clinical health status and effect of treatment. However, there is no or poor correlation between these two variables, which means that they represent different mechanisms. Reduced lung function, such as a low FEV(1) , represents bronchial constriction, what do the symptoms represent? Some symptoms such as breathlessness and shortness of breath seem not to be evidence-based asthma symptoms. Focusing on bronchial obstruction is important in view of the potential risk of asthma attacks, but nonobstructive symptoms occur frequently and may also cause severe discomfort and poor quality of life. Interpreting all symptoms as signs of bronchoconstriction (asthma) may lead to misinterpretation when assessing health status and effect of treatment. Although a 'soft' variable, the strength of symptoms is that they are representing various mechanisms. The physiological preconditions for control and defense of respiration must be considered in the diagnostic process, regardless of inflammation, allergy, psychology, or other etiological factors. Based on studies on dyspnea in cardiopulmonary diseases, including asthma and asthma-like disorders, there seems to be a continuous spectrum of symptoms and mechanisms integrated in a single asthma syndrome.

Rationale for the use of immunomodulatory therapies in the Global Initiative for Asthma (GINA) step V asthma other than oral glucocorticosteroids

Asthma is a major problem worldwide, which is estimated to affect 300 million individuals. The global prevalence ranges from 1% to 18% of the population. The incidence, morbidity and mortality of the condition have increased over the last 50 years despite the development of new anti-asthmatic drugs. Fewer than 1% of the asthmatic population are steroid-dependent, but these patients consume most of the resources and time at asthma units. The consensus documents published by professional societies all support a stepwise therapeutic approach for asthma. However, patients who require frequent or continuous oral corticosteroid administration have received little attention. Due to the severe side-effects of oral corticosteroids when administered over long periods or at high doses, many drugs have been assessed in the search for a possible corticosteroid-sparing agent. Recently, the update of the Global Initiative for Asthma (GINA) introduced a new drug--omalizumab--as an alternative to oral corticosteroids in patients included in step V. Other alternatives include immunosuppressive drugs, among which methotrexate has been found to offer the best benefit/risk ratio. This paper will review, comment and criticize the evidence of the effectiveness of immunomodulatory drugs, as an alternative to oral glucocorticosteroid treatment in GINA step V asthma patients. The experience of the authors combined with the information of the literature will lead to the conclusion that methotrexate and omalizumab are the only advisable drugs and will clarify when and how these drugs should be used.

Cellular pharmacodynamics of immunosuppressive drugs for individualized medicine

The therapeutic effects of immunosuppressive drugs are known to deviate largely between patients, but efficient strategies for the differentiation of patients who show clinical resistance to immunosuppressive therapies have not been established. Accordingly, a considerable number of patients receive treatment with immunosuppressive drugs despite the onset of serious side effects and poor responses. Cellular pharmacodynamics of immunosuppressive drugs in vitro using peripheral lymphocytes derived from each patient, an attractive way to distinguish resistant patients, is respected and has been applied to the carrying out of individualized immunosuppressive therapy. In this article, I summarize experimental procedures for assaying immune cell responses to immunosuppressive drugs in vitro, and highlight the relationship between cellular sensitivity to immunosuppressive drugs and the therapeutic efficacy of drugs in organ transplantation and several immunological disorders. I will also overview the molecular mechanisms and genetic bases for cellular and clinical resistance to immunosuppressive drugs. Lastly, the future clinical prospects for the application of in vitro drug sensitivity tests for "patient-tailored" immunosuppressive therapies are discussed.

[Treatment with nebulized lidocaine in steroid-dependent asthma]

BACKGROUND

The management of glucocorticoid dependent and resistant asthma encompasses a group of problems, affecting as much control of clinical symptoms as the onset of adverse effects to prolonged use of steroids.

MATERIALS AND METHODS

Woman 52 years old, steroid dependent asthma fifteen years ago. She has important adverse effects in consequence of the use of systemic glucocorticoids. The employment of methotrexate attained decrease in the dosage of steroids temporarily. The worsening of the clinical situation and deterioration of secondary effects by use of steroids necessitated treatment with nebulized lidocaine. A 2% solution to initial dosage was administered three times daily. The maximal dosage needed was 80 mg three times daily.

RESULTS

After three months of lidocaine treatment, the patient was able to reduce oral steroids eventually discontinuing these drugs, and the effects secondary to exogenous hypercortisolism disappeared. Moreover, an improvement in clinical symptoms and quality of life was observed with stability in the pulmonary function.

CONCLUSIONS

The use of nebulized lidocaine could be useful and provide alternatives in patients with severe asthma.

The effect of liu-wei-di-huang wan on cytokine gene expression from human peripheral blood lymphocytes

Liu-Wei-Di-Huang Wan (LWDHW) has been used by traditional Chinese doctors to treat asthma patients. This study was to examine the potential effect of this decoction on the regulation of T helper (Th)1- and Th2-type cytokine gene expression in vitro. Peripheral blood mononuclear cells (PBMC) were activated with mitogen for 24 hours in the presence or absence of LWDHW extracts. Concentrations of different cytokines in the culture supernatants were determined with ELISA. RNA isolated from cultured cells was subjected to RT-PCR analysis. The results showed that the expression of all cytokines (Th2-type: IL-4, IL-5, IL-10, or IL-13 and Th1-type: IL-2 and IFN-gamma) examined was inhibited at both RNA and protein levels by LWDHW. Since the cell viability was similar in all cultures, the reduction of cytokine production was not due to the toxicity of LWDHW. Moreover, the cells either retained or increased their capacity to respond to mitogen stimulation after incubation with the LWDHW decoction. Therefore, the data suggest that LWDHW functioned directly on cytokine gene expression from activated PBMC.

Difficult-to-manage asthma. How to pinpoint the exacerbating factors

In difficult-to-manage asthma, effective control depends on identification and alleviation of exacerbating factors, such as ongoing allergen exposure, chronic sinusitis, GERD, and emotional stress. Level of compliance with the prescribed medication regimen should be evaluated in all patients. Hormonal factors (i.e., menses, use of exogenous hormones by female patients, and hyperthyroidism) also can exacerbate asthma. When aggressive management fails, the possibility of a misdiagnosis should be considered. Other conditions that can mimic asthma include COPD, congestive heart failure, airway obstruction due to various causes, vocal cord dysfunction, and esophageal spasm. Referral to an asthma specialist is advised in severe or resistant cases.

Comprehensive asthma management: guidelines for clinicians

Asthma is a chronic inflammatory disease characterized by reversible airway obstruction and nonspecific airway hyperreactivity. Asthma is managed in steps according to disease symptoms and severity. Treatment goals are to decrease symptoms, improve pulmonary function, and reduce overall morbidity and the associated cost of medical care. Antiasthma drugs are a key component of asthma management that are classified as either long-term-control medications that control symptoms and prevent disease exacerbations, or quick-relief medications that rapidly relieve airway obstruction and acute asthma symptoms. Several new leukotriene (LT) modulators have been developed that promise to improve asthma control, including LT receptor antagonists montelukast and zafirlukast and the 5-lipoxygenase inhibitor zileuton. Each decreases symptoms and the use of rescue medication, and improves pulmonary function in patients with mild intermittent to moderate persistent asthma.

Fluticasone propionate results in improved glucocorticoid receptor binding affinity and reduced oral glucocorticoid requirements in severe asthma

BACKGROUND

Inhaled glucocorticoids (iGC) have become important first line agents in the management of moderate-to-severe asthma. Severe asthma is associated with reduced glucocorticoid receptor (GCR) binding affinity.

METHODS

To evaluate the potential impact of inhaled fluticasone propionate on markers of airway inflammation [GCR binding affinity (Kd) and eosinophil cationic protein (ECP)] and oral GC requirements in steroid-dependent asthmatics, we examined the effects of fluticasone propionate (FP) 500 microg or 1000 microg BID and placebo in a double-blind, randomized study of 13 steroid-dependent asthmatics at a single center. Glucocorticoid receptor binding affinity and ECP values were obtained at baseline, 4, 6, 26, and 52 weeks after patients were enrolled into the study. Oral GC dose and FEV1 values were also recorded at each visit.

RESULTS

Inhaled FP resulted in large reductions in oral GC requirement by 6 weeks of therapy while no reduction was seen in the placebo group. All patients in the FP 2000 microg/d group who continued double-blind therapy at 52 weeks were able to eliminate oral prednisone use. In contrast, every patient in the placebo group had to be withdrawn from the study due to poor asthma control. Associated with the oral GC dose reduction on high dose FP therapy, were improvements in GCR binding affinity with the GCR Kd falling from 42.5 nM at baseline to 19.5 nM at 6 weeks (P=.08). The GCR KD values remained stable thereafter with values of 23.5 nM at 26 weeks (P=.02) and 19.5 nM at 52 weeks (P=.01). In addition, high dose FP therapy resulted in reductions in serum ECP values.

CONCLUSION

This study suggests that high dose FP therapy results in significant oral GC sparing effects associated with improved GCR binding affinity and reductions in serum ECP levels in patients with steroid-dependent asthma.