Localization and up-regulation of cysteinyl leukotriene-2 receptor in human allergic nasal mucosa

The IL-31/CysLT2R axis is associated with itching in patients with allergic rhinitis

BACKGROUND

Itching is a troublesome symptom that disturbs patients with allergic rhinitis (AR). The molecular mechanisms underlying itching in AR need to be further illuminated. The aim of this study was to investigate the role of epithelial cell-derived interleukin-31 (IL-31) in nasal itching in AR.

METHODS

A total of 33 patients and 20 healthy control subjects were enrolled in this prospective study. The disease severity of patients with AR was assessed by the total visual analog scale score. The levels of IL-31, cysteinyl leukotriene receptor 1 (CysLT1R), and CysLT2R in the nasal brush specimens from the enrolled subjects were measured by quantitative real-time polymerase chain reaction (RT-PCR) and immunohistochemical staining. The expression of CysLT2R in a human nasal epithelial cell line (HNEpC) was assessed by immunofluorescence staining.

RESULTS

Compared with the control subjects, the protein and mRNA levels of IL-31 and CysLT2R were significantly increased in patients with AR. Higher levels of IL-31 and CysLT2R in nasal epithelial cells were associated with itching but not nasal congestion, rhinorrhea, or sneezing in AR. A significant relationship was found between IL-31 and CysLT2R in nasal epithelial cells, with a correlation coefficient of 0.93. Furthermore, RT-PCR and immunofluorescence staining revealed that IL-31 directly induced CysLT2R expression in HNEpCs. Nasal steroid treatment inhibited IL-31 and CysLT2R expression in 13 patients with AR in vivo.

CONCLUSIONS

Nasal epithelial cell-derived IL-31 might be associated with itching symptoms via CysLT2R in AR.

Evaluation of efficiency and safety of combined montelukast sodium and budesonide in children with cough variant asthma: A protocol for systematic review and meta-analysis

BACKGROUND

Cough variant asthma (CVA) is classified as a distinct form of asthma. As the primary or only symptom, cough is the leading cause for the most prevalent chronic cough among kids. The American College of Clinical Pharmacy, British Thoracic Society, and Chinese guidelines established for diagnosing and treating chronic cough in kids recommend inhaled corticosteroids, combined with leukotriene receptor antagonists when necessary.

METHODS

We will conduct a comprehensive search in major databases using keywords to find studies related to the analysis of montelukast sodium and budesonide for treating CVA in kids. Two reviewers will independently assess the quality of the selected research articles and perform data extraction. Next, we will use the RevMan software (version: 5.3) to conduct the statistical analysis of the present study.

RESULTS

This study will assess the efficacy and safeness of using montelukast sodium and budesonide to treat kids with CVA by pooling the results of individual studies.

CONCLUSION

Our findings will provide vigorous evidence to judge whether montelukast sodium and budesonide therapy is an efficient form of therapy for CVA patients.

ETHICS AND DISSEMINATION

Ethics approval is not needed for the present meta-analysis.

OSF REGISTRATION NUMBER

May 17, 2021.osf.io/cuvjz (https://osf.io/cuvjz/).

Current state and future prospect of the therapeutic strategy targeting cysteinyl leukotriene metabolism in asthma

Asthma is an allergic disorder with dominant type 2 airway inflammation, and its prevalence is increasing worldwide. Inhalation of corticosteroids is the primary treatment for asthma along with add-on drugs, including long-acting β2 agonists and/or cysteinyl leukotriene (cys-LT) receptor antagonists, in patients with poorly controlled asthma. Cys-LTs are composed of leukotriene C4 (LTC₄), LTD₄, and LTE₄, which are enzymatically metabolized from arachidonic acid. These molecules act as inflammatory mediators through different types of high-affinity receptors, namely, CysLT₁, CysLT₂, and CysLT₃ (also named as GPR99). CysLT₁ antagonists possessing anti-inflammatory and bronchodilatory effects can be orally administered to patients with asthma. Recently, molecular biology-based studies have revealed the mechanism of inflammatory responses via other receptors, such as CysLT₂ and CysLT₃, as well as the importance of upstream inflammatory regulators, including type 2 cytokines (e.g., interleukins 4 and 5), in controlling cys-LT metabolism. These findings indicate the therapeutic potential of pharmacological agents targeting cys-LT metabolism-related receptors and enzymes, and antibody drugs neutralizing or antagonizing type 2 cytokines. This review focuses on the current state and future prospect of the therapeutic strategy targeting cys-LT metabolism.

The regulatory actions of retinoic acid on M2 polarization of porcine macrophages

We previously demonstrated that the most bioactive vitamin A metabolite, all-trans retinoic acid (ATRA), increased T helper 2-associated responses induced in pigs by infection with the parasitic nematode Ascaris suum We also showed that ATRA potentiated the mRNA expression of several IL-4 induced chemokines (chemokine (CC motif) ligand 11 [(CCL11), CCL17, CCL22 and CCL26] associated with alternative activation (M2a) in porcine macrophages in vitro. Herein, several mechanisms whereby ATRA affects IL-4 signaling are profiled using large-scale real time PCR and RNA-Seq analysis. Twenty-three genes associated with M2a markers in other species were independently upregulated by both IL-4 and ATRA, including the adenosine receptor A2B (ADORA2B), cysteinyl leukotriene receptor 2 (CYSLTR2) and the vitamin D receptor (VDR). ATRA synergistically enhanced IL-4 up-regulation of Hepatitis A virus cellular receptor 2 (HAVCR2) and transglutaminase 2 (TGM2) and further repressed IL-4 down-regulated CD163 and Cytochrome b-245, beta polypeptide (CYBB) mRNA. Macrophages treated with ATRA exhibited a dose-dependent reduction in phagocytosis of opsonized Staphylococcus aureus. In addition, the combination of IL-4 and ATRA up-regulated the anti-inflammatory protein, IL-1R antagonist (IL1RN) and TGM2. These data indicate that ATRA induces a state of partial alternative activation in porcine macrophages, and amplifies certain aspects of M2a activation induced by IL-4. Given the prevalence of allergic and parasitic diseases worldwide and the close similarities in the porcine and human immune responses, these findings have important implications for the nutritional regulation of allergic inflammation at mucosal surfaces.

Establishing Urinary Leukotriene E4 as a Diagnostic Biomarker for Chronic Rhinosinusitis with Comorbid Asthma and Atopy

OBJECTIVE

While urinary leukotriene E₄ (uLTE₄) is a validated biomarker for the cysteinyl leukotriene pathway, which is central to the pathophysiology of asthma, atopy, and chronic rhinosinusitis (CRS), the contributions of comorbid asthma and atopy to uLTE₄ levels in various CRS subtypes have not been previously characterized. We sought to (1) identify reference values for uLTE₄ in subjects with and without CRS and (2) determine how the presence of comorbid atopy and asthma affects uLTE₄ levels in CRS.

SETTING

Tertiary referral medical center.

SUBJECTS AND METHODS

A prospective case-control study was conducted to compare uLTE₄ levels between patients with CRS and healthy controls. Urinary LTE₄ levels were measured by enzyme immunoassay and were adjusted for urinary creatinine concentrations (pg/mg Cr). Patients with CRS were stratified by the clinical comorbidities to determine normative uLTE₄ values for patients with CRS with and without comorbid asthma or atopy.

RESULTS

A total of 153 patients (mean age, 47.3; 47.1% female) were included in the study. Patients with CRS demonstrated significantly higher concentrations of uLTE₄ than healthy controls (1652 vs 1065 pg/mg Cr, P = .032). Within the group of patients with CRS, comorbid asthma also individually correlated with elevated uLTE₄ levels (1597 pg/mg Cr, P = .0098). Patients with CRS who did not have comorbid allergy and asthma, in contrast, did not have statistically higher uLTE₄ levels than healthy controls (1142 pg/mg Cr, P = .61).

CONCLUSION

Urinary LTE₄ serves as a noninvasive measure of the inflammatory state in CRS. Comorbid asthma and atopy contribute to elevated uLTE₄ levels in CRS.

MicroRNAs: Mediators and Therapeutic Targets to Airway Hyper Reactivity After Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is the most important pathogen correlated to the first-time infant wheezing and later recurrence after its primary infection. RSV infection promotes the bronchial smooth muscle sensitivity to leukotrienes (LTs) in acute stage, causes the extensive inflammatory reaction and the aggregation of Th2-like cells during respiratory tract obstruction. Infants and young children infected with RSV exhibit an increased susceptibility to the exposure of exogenous allergens, easy to suffer from the recurrent wheezing, which prompts that the body is still in a state of inflammation or immunological bias. However, the pathological mechanism is unclear. The recent researches demonstrate that abnormal expression of non-coding microRNAs (miRNAs) can be detected from the peripheral blood and airway tract epithelial of RSV infected infants, which participate the regulation of immune cells polarization and LTs synthesis. Improving the immune tolerance can significantly relieve the airway inflammation and broncho-spasm caused by RSV. In this review, we discuss recent advances in understanding the mechanism of RSV-induced inflammatory reaction and immune dysfunction leading to airway hyper-reactivity. Further, we summarize the potential molecular basis that, in this process, miRNAs, which are produced by airway epithelial cells or peripheral blood mononuclear cells, directly or in the form of exosome to regulate the inflammation programs as well as the function, differentiation and proliferation of immune cells. miRNAs may become a potential bio-marker of detecting severe RSV infection and a novel target of early intervention and therapeutic strategy in recurrent wheezing or asthma related to RSV infection.

A new CysLT1 and CysLT2 receptors-mediated anaphylaxis guinea pig model

Although the effectiveness of CysLT₁ receptor antagonists on asthma has been clinically established, the effects of CysLT₂ receptor antagonists are still unclear. The purpose of this study was to develop a new CysLT₁ and CysLT₂ receptors-mediated anaphylaxis guinea pig model using S-hexyl GSH, a γ-glutamyl transpeptidase (GTP) inhibitor, to suppress conversion of LTC₄ to LTD₄. Actively sensitized guinea pigs were challenged with OVA in the absence or presence of S-hexyl GSH, and survival rate following anaphylactic response was monitored. OVA-induced fatal anaphylaxis in the absence of S-hexyl GSH was almost completely inhibited by montelukast, a CysLT₁ receptor antagonist, but not by the CysLT₂ receptor antagonist BayCysLT₂RA. However, under treatment with S-hexyl-GSH, the inhibitory effect of motelukast was dramatically diminished, whereas that of BayCysLT₂RA was markedly increased. The dual CysLT_1/2 receptor antagonist ONO-6950 effectively inhibited anaphylactic response in both S-hexyl GSH-treated and non-treated animals. LC/MS/MS analysis revealed that S-hexyl GSH treatment actually inhibited LTC₄ metabolism in the blood and lung tissues. Using S-hexyl GSH, we developed a novel CysLT₁ and CysLT₂ receptors-mediated anaphylaxis guinea pig model that can be useful for not only screening both CysLT₂ and CysLT_1/2 receptors antagonists, but also for functional analysis of CysLT₂ receptors.

A dual CysLT1/2 antagonist attenuates allergen-induced airway responses in subjects with mild allergic asthma

BACKGROUND

The cysteinyl leukotrienes (cysLTs) play a key role in the pathophysiology of asthma. In addition to functioning as potent bronchoconstrictors, cysLTs contribute to airway inflammation through eosinophil and neutrophil chemotaxis, plasma exudation, and mucus secretion. We tested the activity of the dual cysLT_1/2 antagonist, ONO-6950, against allergen-induced airway responses.

METHODS

Subjects with documented allergen-induced early (EAR) and late asthmatic response (LAR) were randomized in a three-way crossover study to receive ONO-6950 (200 mg) or montelukast (10 mg) or placebo q.d. on days 1-8 of the three treatment periods. Allergen was inhaled on day 7 two hours postdose, and forced expiratory volume in 1 s (FEV₁ ) was measured for 7 h following challenge. Sputum eosinophils and airway hyperresponsiveness were measured before and after allergen challenge. The primary outcome was the effect of ONO-6950 vs placebo on the EAR and LAR.

RESULTS

Twenty-five nonsmoking subjects with mild allergic asthma were enrolled and 20 subjects completed all three treatment periods per protocol. ONO-6950 was well tolerated. Compared to placebo, ONO-6950 significantly attenuated the maximum % fall in FEV₁ and area under the %FEV₁ /time curve during the EAR and LAR asthmatic responses (P < 0.05) and allergen-induced sputum eosinophils. There were no significant differences between ONO-6950 and montelukast.

CONCLUSIONS

Attenuation of EAR, LAR, and airway inflammation is consistent with cysLT₁ blockade. Whether dual cysLT_1/2 antagonism offers additional benefit for treatment of asthma requires further study.

Expression and localization of GPR99 in human nasal mucosa

OBJECTIVE

The cysteinyl leukotrienes (CysLTs) are lipid mediators that have been implicated in the pathogenesis of allergic rhinitis. Pharmacological studies of CysLTs indicate that two classes of receptors, CysLT₁R and CysLT₂R exist. CysLT₁R is a high affinity LTD₄ receptor with lower affinity for LTC₄, and a CysLT₁R antagonist is currently used to treat asthma and allergic rhinitis. CysLT₂R binds to LTC₄ and LTD₄ with equal affinity. GPR99 (also called GPR80), previously described as an oxoglutarate receptor (OXGR1), has recently emerged as a potential novel receptor with LTE₄. The purpose of this study was to determine the expression and localization of GPR99 protein in the human nasal mucosa.

METHODS

Human turbinates were obtained after turbinectomy from 12 patients with nasal obstruction refractory to medical therapy. GPR99 protein expression was evaluated by western blotting, and the specific cells expressing GPR99 protein identified by immunostaining using a commercial anti-GPR99 (OXGR1) monoclonal antibody.

RESULTS

A 38-kDa band was detected in the western blots of human nasal samples by using the anti-GPR99 monoclonal antibody. We did not find any differences in GPR99 protein levels between allergic and non-allergic nasal mucosa. The immunohistochemical studies revealed that the anti-GPR99 monoclonal antibody mainly labeled vascular smooth muscle cells in the nasal mucosa.

CONCLUSION

These immunohistochemical results suggest that GPR99 may play some roles in the vascular response. Further functional studies will be necessary to clarify the biological significance of the GPR99 receptor in nasal vasculature.

Persistent nasal symptoms and mediator release after continuous pollen exposure in an environmental challenge chamber

BACKGROUND

Immediate- and late-phase reactions are associated with nasal symptoms of patients with allergic rhinitis.

OBJECTIVE

To examine the symptoms and mediators released after continuous allergen exposure in an environmental challenge chamber (ECC).

METHODS

Fifteen patients with Japanese cedar pollinosis were enrolled in this study and continuously exposed to cedar pollen at a concentration of 8,000 grains/m(3) for 3 hours in an ECC. Nasal function tests were performed, and nasal secretions were collected before pollen exposure (0 hour), immediately after exiting the ECC (3 hours), and 6 hours after exiting the ECC (9 hours). Symptom scores were recorded every 30 minutes in the ECC and every 3 hours after exiting the ECC. The frequency of sneezing and nose blowing also was monitored.

RESULTS

The severity of symptoms in the ECC peaked approximately 2 hours after the beginning of pollen exposure and continued more than 6 hours after leaving the ECC. Concentrations of histamine, tryptase, interleukins 5, 3, 33, and 31, and substance P increased over time, whereas that of nasal fractional exhaled nitric oxide decreased.

CONCLUSION

Various mediators are released during continuous allergen exposure, which subsequently induce persistent nasal symptoms. Effective treatment is required to control the intense inflammation observed after allergen exposure.

Leukotriene E4 elicits respiratory epithelial cell mucin release through the G-protein-coupled receptor, GPR99

Cysteinyl leukotrienes (cysLTs), leukotriene C4 (LTC4), LTD4, and LTE4 are proinflammatory lipid mediators with pathobiologic function in asthma. LTE4, the stable cysLT, is a weak agonist for the type 1 and type 2 cysLT receptors (CysLTRs), which constrict airway smooth muscle, but elicits airflow obstruction and pulmonary inflammation in patients with asthma. We recently identified GPR99 as a high-affinity receptor for LTE4 that mediates cutaneous vascular permeability. Here we demonstrate that a single intranasal exposure to extract from the respiratory pathogen Alternaria alternata elicits profound epithelial cell (EpC) mucin release and submucosal swelling in the nasal mucosa of mice that depends on cysLTs, as it is absent in mice deficient in the terminal enzyme for cysLT biosynthesis, LTC4 synthase (LTC4S). These mucosal changes are associated with mast cell (MC) activation and absent in MC-deficient mice, suggesting a role for MCs in control of EpC function. Of the three CysLTRs, only GPR99-deficient mice are fully protected from EpC mucin release and swelling elicited by Alternaria or by intranasal LTE4 GPR99 expression is detected on lung and nasal EpCs, which release mucin to doses of LTE4 one log lower than that required to elicit submucosal swelling. Finally, mice deficient in MCs, LTC4S, or GPR99 have reduced baseline numbers of goblet cells, indicating an additional function in regulating EpC homeostasis. These results demonstrate a novel role for GPR99 among CysLTRs in control of respiratory EpC function and suggest that inhibition of LTE4 and of GPR99 may have therapeutic benefits in asthma.

Immunohistochemical localization of alpha and beta adrenergic receptors in the human nasal turbinate

OBJECTIVE

Adrenergic receptors (ARs) include four general types (α1, α2, β1 and β2), which are found in different target tissues. α-AR agonists are commonly used for decongestant therapy of upper airway diseases. In order to clarify the roles of AR subtypes in the upper airways, we investigated the localization of these receptors by immunohistochemistry.

METHODS

Human turbinates were obtained after turbinectomy from 12 patients with nasal obstruction refractory to medical therapy. The specific cells expressing α- and β-AR proteins were identified by immunostaining using an anti-human AR subtype-specific antibodies (α1A-, α1D-, α2C- and β2-ARs) antibody.

RESULTS

Immunohistochemical analysis revealed that immunoreactivities for α1D- and β2-ARs were densely distributed in submucosal glands. In contrast, immunoreactivities for α1A- and 2C-ARs were densely distributed in vascular smooth muscle.

CONCLUSION

Our results suggested that adrenergic receptor (AR) subtypes had different roles in upper airway diseases, such as allergic rhinitis and nonallergic rhinitis.

Expression of CysLT2 receptors in asthma lung, and their possible role in bronchoconstriction

BACKGROUND

The expression and functional role of CysLT2 receptors in asthma have not been clarified. In this study, we evaluated CysLT2 receptors expression, and effects of CysLT2-and CysLT1/2-receptor antagonists on antigen-induced bronchoconstriction using isolated lung tissues from both asthma and non-asthma subjects.

METHODS

CysLT1 and CysLT2 receptors expression in asthma and non-asthma lung tissue preparations was examined in immunohistochemistry experiments, and their functional roles in antigen-induced bronchoconstriction were assessed using ONO-6950, a dual CysLT1/2-receptor antagonist, montelukast, a CysLT1 receptor antagonist, and BayCysLT2RA, a CysLT2 receptor-specific antagonist.

RESULTS

CysLT1 receptors were expressed on the bronchial smooth muscle and epithelium, and on alveolar leukocytes in 5 in 5 non-asthma subjects and 2 in 2 asthma subjects. On the other hand, although degrees of CysLT2 receptors expression were variable among the 5 non-asthma subjects, the expression in the asthma lung was detected on bronchial smooth muscle, epithelium and alveolar leukocytes in 2 in 2 asthma subjects. In the non-asthma specimens, antagonism of CysLT2 receptors did not affect antigen-induced bronchial contractions, even after pretreatment with the CysLT1-receptor specific antagonist, montelukast. However, in the bronchus isolated from one of the 2 asthma subjects, antagonism of CysLT2 receptors suppressed contractions, and dual antagonism of CysLT1 and CysLT2 receptors resulted in additive inhibitory effect on anaphylactic contractions.

CONCLUSIONS

CysLT2 receptors were expressed in lung specimens isolated from asthma subjects. Activation of CysLT2 receptors may contribute to antigen-induced bronchoconstriction in certain asthma population.

Efficacy of add-on montelukast in nonasthmatic eosinophilic bronchitis: the additive effect on airway inflammation, cough and life quality

Background:

The efficacy of montelukast (MONT), a cysteinyl leukotriene receptor antagonist, in nonasthmatic eosinophilic bronchitis (NAEB), especially its influence on cough associated life quality is still indefinite. We evaluated the efficacy of MONT combined with budesonide (BUD) as compared to BUD monotherapy in improving life quality, suppressing airway eosinophilia and cough remission in NAEB.

Methods:

A prospective, open-labeled, multicenter, randomized controlled trial was conducted. Patients with NAEB (aged 18-75 years) were randomized to inhaled BUD (200 μg, bid) or BUD plus oral MONT (10 μg, qn) for 4 weeks. Leicester cough questionnaire (LCQ) life quality scores, cough visual analog scale (CVAS) scores, eosinophil differential ratio (Eos), and eosinophil cationic protein (ECP) in induced sputum were monitored and compared.

Results:

The control and MONT groups contained 33 and 32 patients, respectively, with similar baseline characteristics. Significant with-in group improvement in CVAS, LCQ scores, Eos, and ECP was observed in both groups during treatment. After 2-week treatment, add-on treatment of MONT was significantly more effective than BUD monotherapy for CVAS decrease and LCQ scores improvement (both P < 0.05). Similar results were seen at 4-week assessment (both P < 0.05). 4-week add-on therapy of MONT also resulted in a higher percentage of patients with normal sputum Eos (<2.5%) and greater decrease of ECP (both P < 0.05).

Conclusions:

MONT combined with BUD was demonstrated cooperative effects in improvement of life quality, suppression of eosinophilic inflammation, and cough remission in patients with NAEB.

Association and management of eosinophilic inflammation in upper and lower airways

This review discussed the contribution of eosinophilic upper airway inflammation includes allergic rhinitis (AR) and chronic rhinosinusitis (CRS) to the pathophysiology and course of asthma, the representative counterpart in the lower airway. The presence of concomitant AR can affect the severity of asthma in patients who have both diseases; however, it is still debatable whether the presence of asthma affects the severity of AR. Hypersensitivity, obstruction and/or inflammation in the lower airway can be detected in patients with AR without awareness or diagnosis of asthma, and AR is known as a risk factor for the new onset of wheeze and asthma both in children and adults. Allergen immunotherapy, pharmacotherapy and surgery for AR can contribute to asthma control; however, a clear preventive effect on the new onset of asthma has been demonstrated only for immunotherapy. Pathological similarities such as epithelial shedding are also seen between asthma and CRS, especially eosinophilic CRS. Abnormal sinus findings on computed tomography are seen in the majority of asthmatic patients, and asthmatic patients with CRS show a significant impairment in Quality of Life (QOL) and pulmonary function as compared to those without CRS. Conversely, lower airway inflammation and dysfunction are seen in non-asthmatic patients with CRS. Treatments for CRS that include pharmacotherapy such as anti-leukotrienes, surgery, and aspirin desensitization show a beneficial effect on concomitant asthma. Acting as a gatekeeper of the united airways, the control of inflammation in the nose is crucial for improvement of the QOL of patients with co-existing AR/CRS and asthma.

The efficacy and safety of selective H1-antihistamine versus leukotriene receptor antagonist for seasonal allergic rhinitis: a meta-analysis

Background

Both selective H₁-antihistamine (SAH) and leukotriene receptor antagonist (LTRA) have been shown to be effective in treating patients with seasonal allergic rhinitis (SAR), but it is still uncertain which treatment option is optimal. This meta-analysis was aimed to compare the efficacy and safety of SAH and LTRA for SAR.

Materials and Methods

PubMed, EMBASE and the Cochrane Library were searched for all eligible studies that compared the efficacy and safety of SAH and LTRA for SAR up to September 7, 2014. The pooled mean difference (MD), odd ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using a fixed- or random-effects model.

Results

Nine studies with 5781 SAR patients were included. The results showed that SAH is superior to LTRA in terms of the daytime eye symptoms score (DESS) and composite symptoms score (CSS) for SAR (MD = 0.06, 95% CI, 0.03 to 0.10, P = 0.000, I² = 99%; MD = 0.03, 95% CI, 0.01 to 0.05, P = 0.010, I² = 98%), whereas LTRA overmatched SAH with respect to the night-time symptoms score (NSS) (MD = −0.04, 95% CI, −0.05 to −0.02, P = 0.000, I² = 97%). Additionally, the results of subgroup analysis indicated that the dose, duration and gender of the patients might impact the comparisons of the effects of SAH and LTRA on their efficacy for SAR.

Conclusion

This meta-analysis suggested that SAH and LTRA have similar effects and safety for SAR, but SAH is more appropriate for daytime nasal symptoms (congestion, rhinorrhea, pruritus and sneezing), while LTRA is better suited for nighttime symptoms (difficulty going to sleep, nighttime awakenings, and nasal congestion on awakening), respectively. Meanwhile, the dose, duration and gender of patients may influence the anti-SAR effects of SAH and LTRA.

Montelukast-induced adverse drug reactions: a review of case reports in the literature

BACKGROUND

Montelukast, a leucotriene receptor antagonist, binds the cysteinyl leucotriene type 1 receptor. Montelukast is commonly prescribed to asthma patients as add-on therapy to inhaled corticosteroids. Several clinical trials emphasized that montelukast can be considered a safe drug. However, recent evidence reconsidered the benefit/risk ratio of the use of montelukast for both paediatric and adult patients.

SUMMARY

The present review analyzed the previous published case reports regarding montelukast-induced adverse drug reactions (ADRs). They included agitation, anxiety, depression, sleep disturbance, hallucinations, suicidal thinking and suicidality, tremor, dizziness, drowsiness, neuropathies and seizures. The immune system can be involved, in particular, cases of Churg-Strauss syndrome have been published. Furthermore, it can induce hypersensitivity reactions, including anaphylaxis and eosinophilic infiltration. In addition, hepatobiliary, pancreatic and uropoietic disorders have been observed. Some of these cases are characterized by severe prognosis (i.e. neurological deficit and fatal hepatotoxicity). Key Message: The use of montelukast can be burdened by several ADRs, of which physicians should be aware in their clinical practice. A better understanding of the mechanisms causing ADRs after using montelukast could help researchers and clinicians in defining a risk-reduction strategy aimed to lessen montelukast toxicity. More accurate epidemiological studies, in order to discover risk factors favouring montelukast-associated ADRs, are demanded.