Blockade of cysteinyl leukotriene-1 receptors suppresses airway remodelling in mice overexpressing GATA-3

Montelukast alleviates inflammation in experimental autoimmune encephalomyelitis by altering Th17 differentiation in a mouse model

Montelukast is a leukotriene receptor antagonist that is known to prevent allergic rhinitis and asthma. Blocking the Cysteinyl leukotriene receptor (CysLTR1), one of the primary receptors of leukotrienes, has been demonstrated to be efficacious in ameliorating experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), through disrupting chemotaxis of infiltrating T cells. However, the role of CysLTR1 in the pathogenesis of MS is not well understood. Here, we show that MS patients had higher expression of CysLTR1 in the circulation and central nervous system (CNS). The majority of CD4⁺ T cells expressed CysLTR1 in MS lesions. Among T-cell subsets, Th17 cells had the highest expression of CysLTR1, and blocking CysLTR1 signalling abrogated their development in vitro. Inhibition of CysLTR1 by montelukast suppressed EAE development in both a prophylactic and therapeutic manner and inhibited myelin loss in EAE mice. Similarly, the in vivo results showed that montelukast inhibited Th17 response in EAE mice and that Th17 cells treated with montelukast had reduced encephalitogenic in adoptive EAE. Our findings strongly suggest that targeting Th17 response by inhibiting CysLTR1 signalling could be a promising therapeutic strategy for the treatment of MS and CNS inflammatory diseases.

Lipoxin and Resolvin Receptors Transducing the Resolution of Inflammation in Cardiovascular Disease

A non-resolving inflammation results in a chronic inflammatory response, characteristic of atherosclerosis, abdominal aortic aneurysms and several other cardiovascular diseases. Restoring the levels of specialized proresolving mediators to drive the chronic cardiovascular inflammation toward resolution is emerging as a novel therapeutic principle. The lipid mediators lipoxins and resolvins exert their proresolving actions through specific G-protein coupled receptors (GPCR). So far, four GPCR have been identified as the receptors for lipoxin A4 and the D- and E-series of resolvins, namely ALX/FPR2, DRV1/GPR32, DRV2/GPR18, and ERV1/ChemR23. At the same time, other pro-inflammatory ligands also activate some of these receptors. Recent studies of genetic targeting of these receptors in atherosclerotic mouse strains have revealed a major role for proresolving receptors in atherosclerosis. The present review addresses the complex pharmacology of these four proresolving GPCRs with focus on their therapeutic implications and opportunities for inducing the resolution of inflammation in cardiovascular disease.

Early control treatment with montelukast in preschool children with asthma: A randomized controlled trial

BACKGROUND

While Japanese guideline recommends initial control treatment for preschool children with asthma symptoms more than once a month, Western guidelines do not. To determine whether control treatment with montelukast was more effective than as-needed β₂-agonists in this population, we conducted a randomized controlled trial.

METHODS

Eligible patients were children aged 1-5 years who had asthma symptoms more than once a month but less than once a week. Patients were randomly assigned in a 1:1 ratio to receive montelukast 4 mg daily for 48 weeks or as-needed β₂-agonists. The primary endpoint was the number of acute asthma exacerbations before starting step-up treatment with inhaled corticosteroids. This study is registered with the University Hospital Medical Information Network clinical trials registry, number UMIN000002219.

RESULTS

From September 2009 to November 2012, 93 patients (47 in the montelukast group and 46 in the no-controller group) were enrolled into the study. All patients were included in the analysis. During the study, 13 patients (28%) in the montelukast group and 23 patients (50%) in the no-controller group had acute exacerbations with the mean numbers of 0.9 and 1.9/year, respectively (P = 0.027). In addition, 10 (21%) and 19 (41%) patients received step-up treatment, respectively. Cumulative incidence of step-up treatment was significantly lower in the montelukast group (hazard ratio 0.45, 95% confidence interval 0.21 to 0.92; P = 0.033).

CONCLUSIONS

Montelukast is an effective control treatment for preschool children who had asthma symptoms more than once a month but less than once a week.

DNA methylation of Th2 lineage determination genes at birth is associated with allergic outcomes in childhood

BACKGROUND

There is now increasing evidence that asthma and atopy originate in part in utero, with disease risk being associated with the altered epigenetic regulation of genes.

OBJECTIVE AND METHODS

To determine the relationship between variations in DNA methylation at birth and the development of allergic disease, we examined the methylation status of CpG loci within the promoter regions of Th1/2 lineage commitment genes (GATA3, IL-4, IL-4R, STAT4 and TBET) in umbilical cord DNA at birth in a cohort of infants from the Southampton Women's Survey (n = 696) who were later assessed for asthma, atopic eczema and atopy.

RESULTS

We found that higher methylation of GATA3 CpGs -2211/-2209 at birth was associated with a reduced risk of asthma at ages 3 (median ratio [median methylation in asthma group/median methylation in non-asthma group] = 0.74, P = .006) and 6-7 (median ratio 0.90, P = .048) years. Furthermore, we demonstrated that the GATA3 CpG loci associated with later risk of asthma lie within a NF-κB binding site and that methylation here blocks transcription factor binding to the GATA3 promoter in the human Jurkat T-cell line. Associations between umbilical cord methylation of CpG loci within IL-4R with atopic eczema at 12 months (median ratio 1.02, P = .028), and TBET with atopy (median ratio 0.98, P = .017) at 6-7 years of age were also observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Our findings provide further evidence of a developmental contribution to the risk of later allergic disorders and suggest that involvement of epigenetic mechanisms in childhood asthma is already demonstrable at birth.

Update on leukotriene, lipoxin and oxoeicosanoid receptors: IUPHAR Review 7

The endogenous ligands for the LT, lipoxin (LX) and oxoeicosanoid receptors are bioactive products produced by the action of the lipoxygenase family of enzymes. The LT receptors BLT1 and BLT2 , are activated by LTB4 and the CysLT1 and CysLT2 receptors are activated by the cysteinyl-LTs, whereas oxoeicosanoids exert their action through the OXE receptor. In contrast to these pro-inflammatory mediators, LXA4 transduces responses associated with the resolution of inflammation through the receptor FPR2/ALX (ALX/FPR2). The aim of the present review is to give a state of the field on these receptors, with focus on recent important findings. For example, BLT1 receptor signalling in cancer and the dual role of the BLT2 receptor in pro- and anti-inflammatory actions have added more complexity to lipid mediator signalling. Furthermore, a cross-talk between the CysLT and P2Y receptor systems has been described, and also the presence of novel receptors for cysteinyl-LTs, such as GPR17 and GPR99. Finally, lipoxygenase metabolites derived from ω-3 essential polyunsaturated acids, the resolvins, activate the receptors GPR32 and ChemR23. In conclusion, the receptors for the lipoxygenase products make up a sophisticated and tightly controlled system of endogenous pro- and anti-inflammatory signalling in physiology and pathology.

Montelukast suppresses epithelial to mesenchymal transition of bronchial epithelial cells induced by eosinophils

Epithelial to mesenchymal transition (EMT) is a mechanism by which eosinophils can induce airway remodeling. Montelukast, an antagonist of the cysteinyl leukotriene receptor, can suppress airway remodeling in asthma. The purpose of this study was to evaluate whether montelukast can ameliorate airway remodeling by blocking EMT induced by eosinophils. EMT induced was assessed using a co-culture system of human bronchial epithelial cells and human eosinophils or the eosinophilic leukemia cell lines, Eol-1. Montelukast inhibited co-culture associated morphological changes of BEAS-2b cells, decreased the expression of vimentin and collagen I, and increased the expression of E-cadherin. Montelukast mitigated the rise of TGF-β1 production and Smad3 phosphorylation. Co-culture of human eosinophils with BEAS-2B cells significantly enhanced the production of CysLTs compared with BEAS-2B cells or eosinophils alone. The increase of CysLTs was abolished by montelukast pre-treatment. Montelukast had similar effects when co-culture system of Eol-1 and BEAS-2B was used. This study showed that montelukast suppresses eosinophils-induced EMT of airway epithelial cells. This finding may explain the mechanism of montelukast-mediated amelioration of airway remodeling in bronchial asthma.

Regulation of an autoimmune model for multiple sclerosis in Th2-biased GATA3 transgenic mice

T helper (Th)2 cells have been proposed to play a neuroprotective role in multiple sclerosis (MS). This is mainly based on “loss-of-function” studies in an animal model for MS, experimental autoimmune encephalomyelitis (EAE), using blocking antibodies against Th2 related cytokines, and knockout mice lacking Th2-related molecules. We tested whether an increase of Th2 responses (“gain-of-function” approach) could alter EAE, the approach of novel GATA binding protein 3 (GATA3)-transgenic (tg) mice that overexpress GATA3, a transcription factor required for Th2 differentiation. In EAE induced with myelin oligodendrocyte glycoprotein (MOG)_35–55 peptide, GATA3-tg mice had a significantly delayed onset of disease and a less severe maximum clinical score, compared with wild-type C57BL/6 mice. Histologically, GATA3-tg mice had decreased levels of meningitis and demyelination in the spinal cord, and anti-inflammatory cytokine profiles immunologically, however both groups developed similar levels of MOG-specific lymphoproliferative responses. During the early stage, we detected higher levels of interleukin (IL)-4 and IL-10, with MOG and mitogen stimulation of regional lymph node cells in GATA3-tg mice. During the late stage, only mitogen stimulation induced higher IL-4 and lower interferon-γ and IL-17 production in GATA3-tg mice. These results suggest that a preexisting bias toward a Th2 immune response may reduce the severity of inflammatory demyelinating diseases, including MS.

Developments in the field of allergy in 2011 through the eyes of Clinical and Experimental Allergy

As in previous years, we felt it would be of value to our readership to summarize the new information provided by the authors who have published in Clinical and Experimental Allergy in 2011 and set this in the context of recent advances in our understanding of the pathogenesis and management of allergic disease in all its many manifestations. In 2011, about 210 articles were published in Clinical and Experimental Allergy including editorials, reviews, opinion articles, guidelines, letters, book reviews and of course at the heart of the journal, papers containing original data. As before, this review is divided into sections based on the way the journal is structured, although this year we have grouped together all the papers dealing with mechanisms of allergic disease, whether they involve patients (clinical mechanisms), pure in vitro studies (basic mechanisms) or animal models (experimental models), as we felt this was a more coherent way to deal with the subject. In the field of asthma and rhinitis, the relationship between airway inflammation and airway dysfunction was of perennial interest to investigators, as were phenotypes and biomarkers. Aspirin hypersensitivity appeared in studies in several papers and there was new interest in asthma in the elderly. The mechanisms involved in allergic disease describe advances in our understanding of T cell responses, the relationship between inflammation and disease, mast cell and basophil activation, steroid resistance and novel therapies. In the section dealing with epidemiology, studies seeking to identify risk factors for allergic disease including vitamin D are prominent, as once again are studies investigating gene-environment interactions. The clinical allergy section focuses on drug allergy, food allergy and immunotherapy. The area of oral immunotherapy for food allergy is well covered and we were grateful to Stephen Durham for guest editing an outstanding special issue on immunotherapy in the centenary year of Leonard Noon's pioneering work. Lastly, in the field of allergens, the interest in component-resolved diagnosis continues to grow and there are also articles describing important novel cultivars and the effect of food processing on the allergenic properties of foods. Another terrific year, full of important and high-quality work,which the journal has been proud to bring to the allergy community.

Montelukast abrogates rhabdomyolysis-induced acute renal failure via rectifying detrimental changes in antioxidant profile and systemic cytokines and apoptotic factors production

In addition to antiasthmatic effect, the cysteinyl leukotriene receptor 1 (CysLT₁) antagonist montelukast shows renoprotective effect during ischemia/reperfusion and cyclosporine-induced renal damage. Here, we proposed that montelukast protects against rhabdomyolysis-induced acute renal failure. Compared with saline-treated rats, at 48 h following the induction of rhabdomyolysis using intramuscular glycerol (10 ml 50% glycerol/kg), significant elevations in serum levels of urea, creatinine, phosphate and acute renal tubular necrosis were observed. This was associated with elevations in serum Fas, interleukin-10, tumor necrotic factor-alpha, and transforming growth factor-beta1 and renal malondialdehyde and nitrite and detrimental reductions in renal catalase and superoxide dismutase activities. The effects of rhabdomyolysis on renal functional, biochemical and structural integrity and the associated changes in cytokines and Fas levels were abolished upon concurrent administration of montelukast (10 mg/kg i.p.) for 3 days (1 day before and 2 days after induction of rhabdomyolysis). Alternatively, administration of the anti-oxidant, α-tocopherol (400 mg/kg i.m.) for 3 days, succeeded in alleviating renal oxidative stress, but had no significant effect on the circulating levels of most cytokines and partially restored kidney functional and structural damage. Serum level of interleukin-6 was not altered by rhabdomyolysis but showed significant elevations in rats treated with montelukast or α-tocopherol. Collectively, motelukast abrogated functional and structural renal damage induced by rhabdomyolysis via ameliorating renal oxidative stress and modulation of systemic cytokines and apoptotic factors production. The results of this work are expected to open new avenues for early prevention of rhabdomyolysis-induced acute renal failure using selective CysLT₁ antagonists such as montelukast.

Influence of inhaled beclomethasone and montelukast on airway remodeling in mice

This study examined the effect of montelukast and beclomethasone on airway remodeling in murine model of asthma. Mice were sensitized by i.p. injection of ovalbumin (OVA) on days 0 and 14, and then challenged by nebulization of 1% OVA 3 days/week for 6 or 10 weeks. Results of 6-week OVA-challenged group showed moderate inflammation, but the 10-week OVA-challenged group exhibited mild inflammation. The OVA challenge (6 and 10 weeks) exhibited marked airway fibrosis, illustrated by significant increase in goblet cell hyperplasia and epithelial thickness, increased lung content of collagen and transforming growth factor-β(1), together with a decrease in nitric oxide production; also, there was an increase in bronchoalveolar lavage fluid level of interleukin-13. Administration of montelukast or beclomethasone before each OVA challenge was capable of restoring most of the measured parameters to near normal levels. Inhalation of beclomethasone has a similar role in airway remodeling as montelukast, but its effects in regulating inflammatory changes is less pronounced than montelukast.

Leukotriene C(4) prevents the complete maturation of murine dendritic cells and modifies interleukin-12/interleukin-23 balance

Leukotriene C(4) is an important mediator in the development of inflammatory reactions and ischaemia. Previous studies have shown that leukotriene C(4) is able to modulate the function of dendritic cells (DCs) and induce their chemotaxis from skin to lymph node. In this study, we decided to evaluate the modulation exerted by leukotriene C(4) on DCs, depending on their status of activation. We showed for the first time that leukotriene C(4) stimulates endocytosis both in immature and lipopolysaccharide (LPS) -activated DCs. Moreover, it suppressed the interleukin-12p70 (IL-12p70) release, but induces the secretion of IL-23 by DCs activated with LPS and promotes the expansion of T helper type 17 (Th17) lymphocytes. Furthermore, blocking the release of IL-23 reduced the percentages of CD4(+) T cells producing IL-17 in a mixed lymphocyte reaction. Ours results suggest that leukotriene C(4) interferes with the complete maturation of inflammatory DCs in terms of phenotype and antigen uptake, while favouring the release of IL-23, the main cytokine involved in the maintenance of the Th17 profile.