Eosinophil Apoptosis and Clearance in Asthma

Peer reviewedPublisher PD

New and developing non-adrenoreceptor small molecule drugs for the treatment of asthma

Introduction: Inhaled corticosteroids (ICS) alone or in combination with an inhaled long-acting beta2-agonist (LABA) are the preferred long-term treatment for adults and adolescents with symptomatic asthma. Additional drugs include leukotriene-receptor antagonists, slow-release theophylline and the long-acting muscarinic antagonist (LAMA) tiotropium (approved in 2015). There is a need for more effective therapies, as many patients continue to have poorly controlled asthma. Areas covered: New and developing long-acting non-adrenoreceptor synthetic drugs for the treatment of symptomatic chronic asthma despite treatment with an ICS alone or combined with a LABA. Data was reviewed from studies published up until November 2016. Expert opinion: Tiotropium improves lung function and has a modest effect in reducing exacerbations when added to ICS alone or ICS and LABA. The LAMAs umeclidinium and glycopyrronium are under development in fixed dose combination with ICS and LABA. Novel small molecule drugs, such as CRTH2 receptor antagonists, PDE4 inhibitors, protein kinase inhibitors and nonsteroidal glucocorticoid receptor agonists and ‘off-label’ use of licensed drugs, such as macrolides and statins are under investigation for asthma, although their effectiveness in clinical practice is not established. To better achieve the goal of developing effective novel small molecule drugs for asthma will require greater understanding of mechanisms of disease and the different phenotypes and endotypes of asthma

Effects of short-term treatment with atorvastatin in smokers with asthma - a randomized controlled trial

<b>Background</b> The immune modulating properties of statins may benefit smokers with asthma. We tested the hypothesis that short-term treatment with atorvastatin improves lung function or indices of asthma control in smokers with asthma.<p></p> <b>Methods</b> Seventy one smokers with mild to moderate asthma were recruited to a randomized double-blind parallel group trial comparing treatment with atorvastatin (40 mg per day) versus placebo for 4 weeks. After 4 weeks treatment inhaled beclometasone (400 ug per day) was added to both treatment arms for a further 4 weeks. The primary outcome was morning peak expiratory flow after 4 weeks treatment. Secondary outcome measures included indices of asthma control and airway inflammation.<p></p> <b>Results</b> At 4 weeks, there was no improvement in the atorvastatin group compared to the placebo group in morning peak expiratory flow [-10.67 L/min, 95% CI -38.70 to 17.37, p=0.449], but there was an improvement with atorvastatin in asthma quality of life score [0.52, 95% CI 0.17 to 0.87 p=0.005]. There was no significant improvement with atorvastatin and inhaled beclometasone compared to inhaled beclometasone alone in outcome measures at 8 weeks.<p></p> <b>Conclusions</b> Short-term treatment with atorvastatin does not alter lung function but may improve asthma quality of life in smokers with mild to moderate asthma. Clinicaltrials.gov identifier: NCT0046382

Repurposing of statins via inhalation to treat lung inflammatory conditions

© 2018 Elsevier B.V. Despite many therapeutic advancements over the past decade, the continued rise in chronic inflammatory lung diseases incidence has driven the need to identify and develop new therapeutic strategies, with superior efficacy to treat these diseases. Statins are one class of drug that could potentially be repurposed as an alternative treatment for chronic lung diseases. They are currently used to treat hypercholesterolemia by inhibiting the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, that catalyses the rate limiting step in the mevalonate biosynthesis pathway, a key intermediate in cholesterol metabolism. Recent research has identified statins to have other protective pleiotropic properties including anti-inflammatory, anti-oxidant, muco-inhibitory effects that may be beneficial for the treatment of chronic inflammatory lung diseases. However, clinical studies have yielded conflicting results. This review will summarise some of the current evidences for statins pleiotropic effects that could be applied for the treatment of chronic inflammatory lung diseases, their mechanisms of actions, and the potential to repurpose statins as an inhaled therapy, including a detailed discussion on their different physical-chemical properties and how these characteristics could ultimately affect treatment efficacies. The repurposing of statins from conventional anti-cholesterol oral therapy to inhaled anti-inflammatory formulation is promising, as it provides direct delivery to the airways, reduced risk of side effects, increased bioavailability and tailored physical-chemical properties for enhanced efficacy

The role of immune mediators in airway inflammation

Asthma is a chronic inflammatory condition of the airways characterised by reversible airflow obstruction, airway hyper-responsiveness and inflammatory infiltrates in the airway walls containing eosinophils, T lymphocytes and mast cells. T helper (Th) lymphocyte subsets, defined by the cytokines they secrete, are thought to play a key role in the in the initiation and perpetuation of chronic airway inflammation. Th2 cells, producing interleukin (IL)-4, IL-5, IL-9 and IL-13, are thought to be of particular importance. In contrast, Thl cells producing interferon (IFN)-y may counteract the development of Th2 responses and so down-regulate the asthmatic response. The prevalence of asthma is increasing but the reasons for this are not fully understood. In addition, some patients do not respond adequately to treatment with corticosteroids, currently the most effective anti-inflammatory agents used routinely in human asthma. There is therefore continual interest in developing new therapeutic agents for asthma. A greater understanding of the regulation of inflammatory responses in asthma will assist in the identification of potential targets for therapeutic intervention. The aims of this thesis were (i) to assess the role of the cytokine IL-18 in allergic airway inflammation by determining IL-18 levels in induced sputum in asthmatic subjects in comparison to normal subjects, and by studies in a murine model of allergic asthma using IL-18 gene deficient mice and (ii) to assess the potential antiinflammatory actions of simvastatin and thymosin beta 4 sulfoxide in the murine asthma model. IL-18 is a pro-inflammatory cytokine which can promote IFN-y secretion and, in association with IL-12, enhance the development of Thl responses. However, in some circumstances it may also stimulate Th2 responses. IL-18 therefore has the potential to suppress or exacerbate allergic airway inflammation. The role of IL-18 in both clinical and experimental asthma remains unclear. Statins are inhibitors of the rate-limiting enzyme, 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, in cholesterol biosynthesis. As such they have been widely used as cholesterol lowering agents in clinical practice. They have previously been shown to have anti-inflammatory properties independent of their cholesterol-lowering ability in clinical studies of atherosclerotic disease and in animal models of Thlmediated inflammation. Thymosin beta 4 sulfoxide (T~4S0) is a 5 kDa peptide. Intracellularly its principal activity is to regulate actin polymerization. Corticosteroid treatment of monocytes in vitro induces the release of T~4S0 extracellularly, where it can inhibit neutrophil chemotaxis. Exogenous administration of T~4S0 has been shown to reduce neutrophilic inflammation in animal models. In this study it is shown that IL-18 is detectable in induced sputum fluid and IL-18 mRNA is expressed in induced sputum cells from asthmatic and nOlmal subjects. IL- 18 protein levels in induced sputum, and IL-18 mRNA expression in induced sputum cells were not significantly different between these groups. IL-18 production was localised to sputum macrophages. However, cigarette smoking significantly reduced IL-18 levels in induced sputum fluid in both asthmatic and normal subjects. In asthmatics, but not normal subjects, the reduction in IL-18 levels in sputum fluid was associated with reduced IL-18 mRNA expression in induced sputum cells. A murine model of allergic asthma, using BALB/C mice sensitised and challenged with ovalbumin (OVA), was used to examine the role of IL-18 in allergic responses in vivo. IL-18 gene knockout (ko) had significantly reduced bronchoalveolar lavage (BAL) total cell count and eosinophilia compared to wild-type (WT) mice. IL-18 ko mice had reduced IL-4 expression in thoracic lymph nodes, as assessed by quantitative peR, and significantly reduced OVA-specific IL-4 secretion from thoracic lymph node cultures assessed by ELISA. Serum OVA-specific IgG 1, IgG2a and IgE and total IgE levels were not significantly different between IL-18 ko and WT mice. The murine model of allergic asthma was also used to examine the anti-inflammatory activities of simvastatin and T~4S0 in a Th2-mediated, eosinophilic condition. Simvastatin treatment, either orally or intraperitoneally, and T~4S0 intraperitoneally reduced the total inflammatory cell infiltrate and eosinophilia in BAL fluid in response to inhaled OV A challenge. At higher doses of simvastatin intraperitoneally, a histological reduction in inflammatory infiltrates in the lungs was observed. Treatment with simvastatin intraperitoneally, but not orally, and T~4S0 were also associated with a reduction in IL-4 and IL-5 levels in BAL fluid. OVA-induced IL-4 and IL-5 secretion was reduced in thoracic lymph node cultures from both simvastatin-treated and T~4S0-treated mice. Neither simvastatin nor T~4S0 treatment altered serum total IgE or OVA-specific IgG 1 and IgG2a levels. The results described show that IL-18 can be detected in the induced sputum fluid of asthmatic and normal subjects and that cigarette smoking significantly reduces its levels. Studies in a murine model of allergic asthma suggest that IL-18 has a proinflammatory role in allergic airway inflammation, at least in part through its ability to induce IL-4 secretion. Both simvastatin and thymosin beta 4 sulfoxide had convincing anti-inflammatory properties in the murine model of asthma used, and these agents, or related compounds, may have therapeutic potential in human asthma

Do Statins Improve Outcomes in Patients With Asthma on Inhaled Corticosteroid Therapy? A Retrospective Analysis of the Mississippi Medicaid Database 2002-2004.

Animal model studies and clinical trials have looked at the potential benefits of the anti-inflammatory properties of statins in asthma management with contradictory results. Therefore, the objective of this study is to determine if asthma patients on concurrent statin therapy are less likely to have asthma-related hospitalizations and emergency room (ER) visits. We conducted a retrospective cohort study using Medicaid data for 2002–2004. Asthma patients ?18 years old were identified using the ICD9 code 493.xx, from Jul 1, 2002 through Dec 31, 2003. The index date for an exposed subject was any date within the identification period, 180 days prior to which the subject had at least 1 inhaled corticosteroid (ICS) prescription and at least an 80% adherence rate to statins. Medicaid beneficiaries identified as asthmatics and on ICS therapy, but not on statins were selected as the unexposed population. Each subject in the exposed group was matched to 2 subjects from the unexposed population using propensity scores computed using age, gender, race, urban/rural region and Charlson Comorbidity Index. The two groups were follofor 1 year beginning on the index date, and their outcomes in terms of hospitalizations and ER visits were compared using conditional logistic regression, further adjusted for adherence to ICS therapy, average number of short-acting ? agonists per subject, prior hospitalizations, ER, lab and office visits due to asthma. After matching, there were 479 exposed subjects with 958 corresponding controls. After adjusting for the above mentioned covariates, asthma patients not on concurrent statin therapy are almost two times as likely to have hospitalization and/or ER visits or both due to asthma (adjusted OR = 0.55; 95% CI [0.37, 0.84]; p = 0.0059), in comparison to patients on statin therapy. Similarly, they are also twice as likely to visit the ER due to asthma exacerbations as patients on statins (adjusted OR = 0.48; 95% CI [0.28, 0.82]; p = 0.0069). The findings of this study suggest that there may be beneficial effects of statins in preventing asthma exacerbations. Further prospective investigations are required to provide conclusive evidence

Do the pleiotropic effects of statins in the vasculature predict a role in inflammatory diseases?

Pleiotropic effects are now described for the 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (or statins) that might have utility in the context of chronic inflammatory autoimmune disease. Here we discuss the pharmacology and established uses of statins and in this context describe potential anti-inflammatory and immune-modulatory effects. An extensive in vitro data set defines roles for statins in modifying endothelial function, particularly with respect to adhesion molecule expression and apoptosis. Broader effects on leukocyte function have now emerged including altered adhesion molecule expression, cytokine and chemokine release and modulation of development of adaptive immune responses via altered MHC class II upregulation. In vivo data in several inflammatory models, including collagen-induced inflammatory arthritis and experimental autoimmune encephalomyelitis, suggest that such effects might have immune-modulatory potential. Finally, a recent clinical trial has demonstrated immunomodulatory effects for statins in patients with rheumatoid arthritis. Together with their known vasculoprotective effects, this growing body of evidence provides compelling support for longer-term trials of statin therapy in human disease such as rheumatoid arthritis

Self-assembling nanoparticles containing dexamethasone as a novel therapy in allergic airways inflammation.

Nanocarriers can deliver a wide variety of drugs, target them to sites of interest, and protect them from degradation and inactivation by the body. They have the capacity to improve drug action and decrease undesirable systemic effects. We have previously developed a well-defined non-toxic PEG-dendritic block telodendrimer for successful delivery of chemotherapeutics agents and, in these studies, we apply this technology for therapeutic development in asthma. In these proof-of-concept experiments, we hypothesized that dexamethasone contained in self-assembling nanoparticles (Dex-NP) and delivered systemically would target the lung and decrease allergic lung inflammation and airways hyper-responsiveness to a greater degree than equivalent doses of dexamethasone (Dex) alone. We found that ovalbumin (Ova)-exposed mice treated with Dex-NP had significantly fewer total cells (2.78 ± 0.44 × 10(5) (n = 18) vs. 5.98 ± 1.3 × 10(5) (n = 13), P<0.05) and eosinophils (1.09 ± 0.28 × 10(5) (n = 18) vs. 2.94 ± 0.6 × 10(5) (n = 12), p<0.05) in the lung lavage than Ova-exposed mice alone. Also, lower levels of the inflammatory cytokines IL-4 (3.43 ± 1.2 (n = 11) vs. 8.56 ± 2.1 (n = 8) pg/ml, p<0.05) and MCP-1 (13.1 ± 3.6 (n = 8) vs. 28.8 ± 8.7 (n = 10) pg/ml, p<0.05) were found in lungs of the Dex-NP compared to control, and they were not lower in the Dex alone group. In addition, respiratory system resistance was lower in the Dex-NP compared to the other Ova-exposed groups suggesting a better therapeutic effect on airways hyperresponsiveness. Taken together, these findings from early-stage drug development studies suggest that the encapsulation and protection of anti-inflammatory agents such as corticosteroids in nanoparticle formulations can improve efficacy. Further development of novel drugs in nanoparticles is warranted to explore potential treatments for chronic inflammatory diseases such as asthma

Examining the role of ABC lipid transporters in pulmonary lipid homeostasis and inflammation

© The Author(s). 2017 Open Access Respiratory diseases including asthma and chronic obstructive pulmonary disease (COPD) are characterised by excessive and persistent inflammation. Current treatments are often inadequate for symptom and disease control, and hence new therapies are warranted. Recent emerging research has implicated dyslipidaemia in pulmonary inflammation. Three ATP-binding cassette (ABC) transporters are found in the mammalian lung - ABCA1, ABCG1 and ABCA3 - that are involved in movement of cholesterol and phospholipids from lung cells. The aim of this review is to corroborate the current evidence for the role of ABC lipid transporters in pulmonary lipid homeostasis and inflammation. Here, we summarise results from murine knockout studies, human diseases associated with ABC transporter mutations, and in vitro studies. Disruption to ABC transporter activity results in lipid accumulation and elevated levels of inflammatory cytokines in lung tissue. Furthermore, these ABC-knockout mice exhibit signs of respiratory distress. ABC lipid transporters appear to have a crucial and protective role in the lung. However, our knowledge of the underlying molecular mechanisms for these benefits requires further attention. Understanding the relationship between cholesterol and inflammation in the lung, and the role that ABC transporters play in this may illuminate new pathways to target for the treatment of inflammatory lung diseases