The role of leukotrienes in allergic rhinitis: a review

Screening of Prospective Plant Compounds as H1R and CL1R Inhibitors and Its Antiallergic Efficacy through Molecular Docking Approach

Allergens have the ability to enter the body and cause illness. Leukotriene is the widespread allergen which could stimulate mast cells to discharge histamine which causes allergy symptoms. An effective strategy for treating leukotriene-induced allergy is to find the inhibitors of leukotriene or histamine activity from phytochemicals. For this purpose, a library of 8,500 phytochemicals was generated using MOE software. The structures of histamine-1 receptor and cysteinyl leukotriene receptor-1 were predicted by the homology modeling method through the SWISS model. The phytochemicals were docked with predicted structures of histamine-1 and cysteinyl leukotriene receptor-1 in MOE software to determine the binding affinity of the phytochemicals against the targets. Moreover, chemoinformatics properties and ADMET of phytochemicals were assessed to find the drug likeness behavior of compounds. Compound ID 10054216 has the lowest $S$ -score value for H-1 receptor that is -18.9186 kcal/mol which is lower than the value of standard -15.167 kcal/mol. The other compounds 393471, 71448939, 10722577, and 442614 also showed good $S$ -score values than the standard. Moreover, compound ID 11843082 has the lowest $S$ -score value for CL1R that is -15.481 kcal/mol which is lower than the value of standard -12.453 kcal/mol. The other compounds 72284, 5282102, 66559251, and 102506430 also showed good $S$ -score values than the standard. In this research article, we performed molecular docking to find the best inhibitors against H1R and CL1R and their antiallergic efficacy. This in silico knowledge will be helpful in near future for the design of novel, safe, and less costing H-1 receptor and CL1R inhibitors with the aim to improve human life quality.

HIF1α Deficiency in Dendritic Cells Attenuates Symptoms and Inflammatory Indicators of Allergic Rhinitis in a SIRT1-Dependent Manner

BACKGROUND

Allergic rhinitis is the most prevalent atopic disorder worldwide. Inflammation is believed to participate in allergic rhinitis. Previous studies indicate that hypoxia-inducible factor (HIF) promotes the development of allergic rhinitis, and dendritic cells are also involved in allergic rhinitis.

METHODS

We explored the consequences of HIF1α deficiency in dendritic cells on allergic rhinitis. Allergic rhinitis in mice was induced by ovalbumin (OVA). The levels of IgE, leukotriene C4 (LTC4), eosinophil cationic protein (ECP), prostaglandin D2 (PGD2), IFN-γ, IL-2, IL-4, IL-5, IL-10, and IL-13 in serum or nasal lavage fluid (NLF) were detected by ELISA. Inflammatory cells in NLF were counted by hemocytometer. The protein levels of p-ERK1/2, p-p38, p-JNK2, SIRT1, p-IκBα, and p65 were determined by Western blot.

RESULTS

HIF1α deficiency in dendritic cells (HIF1αCD11c-/-) decreased sneezing and nasal rubbing, the production of OVA-specific IgE, LTC4, and ECP in serum and NLF, and the numbers of leukocytes, eosinophils, lymphocytes, and neutrophils in NLF. Th1 cytokines increased, while Th2 cytokines decreased in HIF1aCD11c-/- mice. SIRT1/NF-κB signaling was inhibited in HIF1αCD11c-/- mice, while SIRT1 inhibitor administration in HIF1αCD11c-/- mice attenuated the symptoms and inflammatory indicators of allergic rhinitis.

CONCLUSION

HIF1α deficiency in dendritic cells attenuates symptoms and inflammatory indicators of allergic rhinitis in a SIRT1-dependent manner.

Comparison of Antileukotrienes and Antihistamines in the Treatment of Allergic Rhinitis

Background

The aim of this study was to compare the effect of antileukotriene (anti-LT), antihistamine, and a combination of anti-LT and antihistamine on the symptoms and nasal resistance in allergic rhinitis patients.

Methods

We performed a placebo-controlled study, with 120 persistent, moderate to severe allergic rhinitis patients randomly selected to receive the different treatments for 4 weeks: no treatment, 10 mg of cetirizine once per day, 20 mg of zafirlukast once per day, 20 mg of zafirlukast twice per day, a combination of 20 mg of zafirlukast and 10 mg of cetirizine once per day, or a combination of 20 mg of zafirlukast twice per day and 10 mg cetirizine once per day. The nasal secretion nitric oxide (NO) concentration, nasal symptom score, and nasal resistance were measured before and after treatment.

Results

Total symptom scores improved in each treated group compared with the control group (p < 0.05). Nasal obstruction significantly improved in the anti-LT-treated groups (p < 0.05). High-dose anti-LT or the combination of low-dose anti-LT and antihistamine significantly improved allergy symptoms compared with no treatment, low-dose anti-LT, or antihistamine alone (p < 0.05). Furthermore, anti-LT decreased NO concentration in nasal secretions (p < 0.05), regardless of the dose administered.

Conclusion

These results suggest that high-dose anti-LT alone or the combination of low-dose anti-LY and antihistamine can effectively treat allergic rhinitis.

Antileukotrienes in upper airway inflammatory diseases

Leukotrienes (LTs) are a family of inflammatory mediators including LTA4, LTB4, LTC4, LTD4, and LTE4. By competitive binding to the cysteinyl LT1 (CysLT1) receptor, LT receptor antagonist drugs, such as montelukast, zafirlukast, and pranlukast, block the effects of CysLTs, improving the symptoms of some chronic respiratory diseases, particularly bronchial asthma and allergic rhinitis. We reviewed the efficacy of antileukotrienes in upper airway inflammatory diseases. An update on the use of antileukotrienes in upper airway diseases in children and adults is presented with a detailed literature survey. Data on LTs, antileukotrienes, and antileukotrienes in chronic rhinosinusitis and nasal polyps, asthma, and allergic rhinitis are presented. Antileukotriene drugs are classified into two groups: CysLT receptor antagonists (zafirlukast, pranlukast, and montelukast) and LT synthesis inhibitors (5-lipoxygenase inhibitors such as zileuton, ZD2138, Bay X 1005, and MK-0591). CysLTs have important proinflammatory and profibrotic effects that contribute to the extensive hyperplastic rhinosinusitis and nasal polyposis (NP) that characterise these disorders. Patients who receive zafirlukast or zileuton tend to show objective improvements in, or at least stabilisation of, NP. Montelukast treatment may lead to clinical subjective improvement in NP. Montelukast treatment after sinus surgery can lead to a significant reduction in eosinophilic cationic protein levels in serum, with a beneficial effect on nasal and pulmonary symptoms and less impact in NP. Combined inhaled corticosteroids and long-acting β-agonists treatments are most effective for preventing exacerbations among paediatric asthma patients. Treatments with medium- or high-dose inhaled corticosteroids, combined inhaled corticosteroids and LT receptor antagonists, and low-dose inhaled corticosteroids have been reported to be equally effective. Antileukotrienes have also been reported to be effective for allergic rhinitis.

Role of hematopoietic prostaglandin D synthase in biphasic nasal obstruction in guinea pig model of experimental allergic rhinitis

We investigated the role of hematopoietic prostaglandin D synthase (H-PGDS) in biphasic nasal obstruction in allergic rhinitis using a new specific inhibitor, (N-methoxy-N-methyl)-4-(5-benzoylbenzimidazole-2-yl)-3,5-dimethylpyrrole-2-carboxamide hydrochloride (TAS-204). First, we developed a novel guinea pig model of allergic rhinitis. Guinea pigs sensitized to ovalbumin without adjuvant were challenged with intranasal exposure to ovalbumin once a week. After the 3rd antigen challenge, they exhibited biphasic nasal obstruction. Additionally, analysis of nasal lavage fluid revealed an increase in the level of prostaglandin D(2) in both early and late phases. Treatment with oral TAS-204 for 15 days during the period of antigen challenges suppressed increases in nasal airway resistance in both phases. It is noteworthy that the late phase nasal obstruction was almost completely abrogated by inhibiting H-PGDS alone. Eosinophil infiltration in nasal lavage fluid and nasal hyperresponsiveness to histamine was also reduced by TAS-204 administration. These findings suggest that H-PGDS plays a critical role in the development of allergic rhinitis, especially in the induction of late phase nasal obstruction.

Current Thinking on the Relationship Between Rhinosinusitis and Asthma

An observation made initially on clinical grounds and epidemiologic evidence, i.e., that rhinosinusitis and asthma are closely linked diseases is now supported by a growing body of scientific evidence. Most recent evidence supports the characterization of rhinosinusitis and asthma as two compartmental expressions of a common mucosal susceptibility to exogenous stimuli. In addition, there is evidence that the compartmental processes can affect and amplify each other via a systemic intermediary. The bone marrow is involved in this process, and IL-5 may be a key cytokine for orchestrating the systemic interaction. These facts argue that rhinosinusitis and asthma are not simply localized disease processes but part of a systemic inflammatory disease affecting the respiratory tract. They also provide a compelling rationale for combined treatment strategies with consideration of the treatment of rhinosinusitis as a means of improving asthma control and monitoring for signs of bronchial involvement in those with rhinosinusitis.

Hyperleukotrieneuria in patients with allergic and inflammatory disease

Cysteinyl leukotrienes (CysLTs: leukotrienes C(4), D(4), and E(4)) have long been implicated in the pathogenesis of asthma and several allergic diseases. LTE(4) has been identified as a major metabolite of LTC(4), and urinary LTE(4) (U-LTE(4)) is considered as the most reliable analytic parameter for monitoring the endogenous synthesis of CysLTs. From recent studies on the U-LTE(4) associated with adult stable asthma we identified four factors for hyperleukotrieneuria, namely, aspirin intolerance, eosinophilic nasal polyposis (ENP), vasculitis, and severe asthma. In ENP, there is prominent infiltration of eosinophils in the sinus and polyp tissues, which is linked to adult asthma and aspirin sensitivity, and ENP is the most important factor for the overproduction of CysLTs in asthmatics. We also demonstrated that anaphylaxis and eosinophilic pneumonia (EP) are associated with a marked increase in the U-LTE(4) concentration. Under these disease conditions, U-LTE(4) may be one of the candidate biomarkers. Moreover, the changes in U-LTE(4) concentrations may provide valuable information concerning therapeutic targets.

Therapeutic effect of montelukast, a cysteinyl leukotriene receptor 1 antagonist, on Japanese patients with seasonal allergic rhinitis

BACKGROUND

Secretion of nasal discharge was enhanced and airway-resistance in the nasal cavity was augmented, resulting in nasal congestion, when leukotrienes were administered to the nasal mucosa. These results indicate that leukotrienes play an important role in the pathogenesis of allergic rhinitis.

METHODS

A double-blind clinical study was carried out to evaluate the efficacy and the safety of montelukast, a cysteinyl leukotriene receptor 1 antagonist, 5 mg, 10 mg or placebo orally administered once daily at bedtime for 2 weeks, to Japanese patients with seasonal allergic rhinitis. The composite nasal symptom scores (average over the 2-week treatment period) were compared among the montelukast 5 mg and 10 mg groups with the placebo group.

RESULTS

The composite nasal symptom score significantly improved in the montelukast 5 mg and 10 mg groups compared with the placebo group. The administration of montelukast 5 mg or 10 mg once daily was well tolerated and the safety profiles were similar to those of the placebo. There were no significant differences in the incidences of adverse experience or drug-related adverse experience among the montelukast 5 mg, 10 mg groups and the placebo group.

CONCLUSIONS

Both montelukast 5 mg and 10 mg doses show clinically meaningful efficacy for the treatment of patients with seasonal allergic rhinitis and the safety profiles of those are comparable to that of the placebo.

Urinary leukotrienes in patients with nasal polyposis

Objectives

To compare urinary leukotriene E4 (ULT) level in patients with nasal polyposis (NP) with and without aspirin intolerance and allergic rhinitis (AR), and correlate it with disease severity.

Study Design and Setting

Prospective study from November 2005 to November 2006. Patients with NP (n = 30) and AR (n = 35) were included. The concentration of ULT was measured in both groups. Oral provocation test with aspirin was performed to patients with NP. ULT level between both groups was compared and correlated with NP disease severity.

Results

ULT concentration was elevated on NP and AR. The patients with NP and aspirin intolerance (n = 4) presented higher levels of ULT compared to aspirin-tolerant patients. Leukotriene concentration was not correlated with NP severity.

Conclusions

Patients with NP and aspirin intolerance have increased ULT excretion; thus their measurement can be used as an indicator of arachidonic acid metabolism alteration.

Childhood allergic rhinitis predicts asthma incidence and persistence to middle age: a longitudinal study

BACKGROUND

The association between allergic rhinitis and asthma is well documented, but the temporal sequence of this association has not been closely examined.

OBJECTIVE

We sought to assess the associations between childhood allergic rhinitis and (1) asthma incidence from preadolescence to middle age and (2) asthma persistence to middle age.

METHODS

Data were gathered from the 1968, 1974, and 2004 surveys of the Tasmanian Asthma Study. Cox regression was used to examine the association between childhood allergic rhinitis and asthma incidence in preadolescence, adolescence, and adult life. Binomial regression was used to examine the association between childhood allergic rhinitis and asthma beginning before the age of 7 years and persisting at age 44 years.

RESULTS

Childhood allergic rhinitis was associated with a significant 2- to 7-fold increased risk of incident asthma in preadolescence, adolescence, or adult life. Childhood allergic rhinitis was associated with a 3-fold increased risk of childhood asthma persisting compared with remitting by middle age.

CONCLUSIONS

Childhood allergic rhinitis increased the likelihood of new-onset asthma after childhood and the likelihood of having persisting asthma from childhood into middle age.

CLINICAL IMPLICATIONS

Asthma burden in later life might be reduced by more aggressive treatment of allergic rhinitis in early life.

Differential responses to various classes of drugs in a model of allergic rhinitis in guinea pigs

Different drugs from various pharmacological classes were compared for their ability to protect against the nasal effects of acute allergen challenge in a guinea pig model. In the model, sneezing and nose rubbing were recorded after an initial allergen challenge in guinea pigs previously sensitized to egg albumin. Four days later the same guinea pigs were re-challenged a second time when anesthetised. In these anaesthetized animals, nasal airway pressure, pulmonary inflation pressure and cellular infiltration into nasal lavage fluid were measured. The drug tested were autacoid antagonists (mepyramine--3mg/kg, cetirizine--3mg/kg and montelukast--10mg/kg), L-NAME (10 or 20mg/kg), heparin (20mg/kg) and dexamethasone (20mg/kg) given either intraperitoneally or intravenously; all were given shortly before challenge. Sneezing induced by allergen challenge was statistically significantly reduced by mepyramine, cetirizine and dexamethasone whereas only cetirizine reduced nose rubbing. Changes in nasal airway pressure due to allergen exposure were reduced by cetirizine, montelukast, L-NAME, and heparin, but not by mepyramine, nor dexamethasone. In the presence of L-NAME, nasal airway pressure actually changed in the opposite direction. Cellular infiltration, as assessed by cytometry in nasal lavage fluid 60min after acute allergen challenge, was reduced by montelukast and heparin but not by antihistamines, L-NAME nor dexamethasone. This pattern of effects of the drugs, given by doses and routes previously described in the literature as being effective was not completely consistent with expected responses. The lack of effect of dexamethasone probably reflects the fact that it was given acutely whereas in the clinic chronic administration is used. The two antihistamines were not identical in their actions, presumably reflecting the fact that cetirizine has therapeutic actions not entirely confined to blockade of H1 receptors. Montelukast has not been reported to have major effects on sneezing and itching in the clinic but reduces nasal obstruction (lower nasal airway pressure or nasal patency). Montelukast's effects on cellular infiltration indicate the possible involvement of leukotrienes. Heparin has actions on inflammatory cell infiltration. This could explain its profile of reducing both cellular infiltration, and increased nasal airway pressure.

Evolving role of leukotrienes in the pathogenesis of viral infections, including otitis media

Otitis media (OM) is one of the most common childhood disorders and has been associated with an alarming rise in prevalence. Because medical therapy with antibiotics, antihistamines, decongestants, and corticosteroids has no demonstrable efficacy in the treatment of OM, the mainstay of treatment is surgical intervention. Although effective, surgical treatment is quite expensive and exposes patients to the risks associated with general anesthesia. Results of recent studies suggest that locally produced leukotrienes may play a role in the pathogenesis of OM. As such, a potential candidate for treatment of OM is the leukotriene receptor antagonist, montelukast, which has been approved by the US Food and Drug Administration for the treatment of asthma and/or allergic rhinitis. If proven effective, this drug's safety/convenience profiles and indication for children as young as 6 months of age would make it suitable for treatment of OM, and perhaps even prophylaxis of OM in at-risk populations.

Interactive effect of histamine and prostaglandin D2 on nasal allergic symptoms in rats

This study was undertaken to investigate the interactive effect of histamine and prostaglandin D(2) in nasal allergic symptoms in rats. The intranasal application of histamine at doses lower than 10 mumol/site caused no sneezing or nasal rubbing. In addition, prostaglandin D(2) also showed no significant increase in these responses, even at a dose of 10 nmol/site. On the other hand, the simultaneous instillation of histamine and prostaglandin D(2) resulted in a 1000 times more potent effect in inducing nasal symptoms than the administration of histamine alone. Thus, prostaglandin D(2) enhanced the actions of histamine in inducing sneezing and nasal rubbing in a dose-dependent manner, and significant effects were observed at doses higher than 1 nmol/site. The responses induced by the simultaneous application of histamine and prostaglandin D(2) were inhibited by chlorpheniramine, cyproheptadine, BW A868C and ramatroban. Chlorpheniramine and cyproheptadine showed the dose-related inhibition of nasal symptoms induced by the combined administration of histamine (10 nmol) and prostaglandin D(2) (10 nmol), but the effect of cyproheptadine was relatively weak compared with chlorpheniramine. Moreover, BW A868C and ramatroban also showed the inhibition of nasal symptoms induced by the simultaneous administration of histamine and prostaglandin D(2) in a dose-dependent manner. BW A868C was more potent in inhibiting the nasal symptoms than ramatroban. These results clearly indicate that prostaglandin D(2) showed a synergistic effect on sneezing and nasal rubbing induced by histamine in rats, and its effect occurred through both prostaglandin D(2) and CRTH2 (chemoattractant receptor-homologous molecule expressed on TH2 cells) receptors.

Oxymetazoline Inhibits Proinflammatory Reactions: Effect on Arachidonic Acid-Derived Metabolites

The nasal decongestant oxymetazoline effectively reduces rhinitis symptoms. We hypothesized that oxymetazoline affects arachidonic acid-derived metabolites concerning inflammatory and oxidative stress-dependent reactions. The ability of oxymetazoline to model pro- and anti-inflammatory and oxidative stress responses was evaluated in cell-free systems, including 5-lipoxygenase (5-LO) as proinflammatory, 15-lipoxygenase (15-LO) as anti-inflammatory enzymes, and oxidation of methionine by agglomerates of ultrafine carbon particles (UCPs), indicating oxidative stress. In a cellular approach using canine alveolar macrophages (AMs), the impact of oxymetazoline on phospholipase A(2) (PLA(2)) activity, respiratory burst and synthesis of prostaglandin E(2) (PGE(2)), 15(S)-hydroxy-eicosatetraenoic acid (15-HETE), leukotriene B(4) (LTB(4)), and 8-isoprostane was measured in the absence and presence of UCP or opsonized zymosan as particulate stimulants. In cell-free systems, oxymetazoline (0.4-1 mM) inhibited 5-LO but not 15-LO activity and did not alter UCP-induced oxidation of methionine. In AMs, oxymetazoline induced PLA(2) activity and 15-HETE at 1 mM, enhanced PGE(2) at 0.1 mM, strongly inhibited LTB(4) and respiratory burst at 0.4/0.1 mM (p < 0.05), but did not affect 8-isoprostane formation. In contrast, oxymetazoline did not alter UCP-induced PLA(2) activity and PGE(2) and 15-HETE formation in AMs but inhibited UCP-induced LTB(4) formation and respiratory burst at 0.1 mM and 8-isoprostane formation at 0.001 mM (p < 0.05). In opsonized zymosan-stimulated AMs, oxymetazoline inhibited LTB(4) formation and respiratory burst at 0.1 mM (p < 0.05). In conclusion, in canine AMs, oxymetazoline suppressed proinflammatory reactions including 5-LO activity, LTB(4) formation, and respiratory burst and prevented particle-induced oxidative stress, whereas PLA(2) activity and synthesis of immune-modulating PGE(2) and 15-HETE were not affected.

Role of Leukotriene Inhibitors in the Postoperative Management of Nasal Polyps

This was a prospective double blind comparative study on 40 patients. It compared the effects of the leukotriene receptor antagonist montelukast and beclomethasone nasal spray on the post-operative course of patients with sinonasal polyps. All patients underwent endoscopic sphenoethmoidectomy and were randomized post-operatively into two groups. Group I: 20 patients (9 females and 11 males) age 17 to 67 (32.4 +/- 9.5 years), receiving 10 mg montelukast orally daily and Group II: 20 patients (6 females and 14 males) age 17 years to 57 years (33.5 +/- 11.9 years), receiving 400 ug beclomethasone local sprays daily. All patients were followed up for 1 year and a symptom score was recorded throughout this period. There was a significant reduction in symptom scores in both groups throughout the study period. In the montelukast group improvement was more marked in itching, post-nasal discharge and headache. The control of sneezing and rhinorrhea was comparable in both groups with a marginal advantage of montelukast. Steroids had a more marked effect on smell disturbances and obstruction. There was no difference in the recurrence rate or in the need for rescue medications between both groups. Both drugs seem to have a complementary action and further studies are needed to determine which patients should receive which treatment.

Neuronal Plasticity in Persistent Perennial Allergic Rhinitis

OBJECTIVE

Persistent perennial allergic rhinitis belongs to the most frequent diseases in occupational and environmental medicine. Because the innervation may play a role in the pathogenesis of the disease, the present study analyzed nasal mucosal nerve profiles.

METHODS

Neuropeptide-containing nerve fibers were examined using immunohistochemistry and related to eosinophil and mast cell numbers.

RESULTS

In contrast to constant numbers of mast cells, there was a significant increase in the number of eosinophils. Immunohistochemistry for calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP), and neuropeptide tyrosine (NPY) revealed abundant staining of mucosal nerves. Semiquantitative assessment of nerve fiber neuropeptide density demonstrated a significant increase of VIP-positive fibers in rhinitis tissues.

CONCLUSIONS

The present data indicate a differential regulation of neuropeptide-containing nerve fibers with increased numbers of VIPergic fibers suggesting a modulatory role of the upper airway innervation in perennial allergic rhinitis.

Participation of chemical mediators in the development of experimental allergic conjunctivitis in rats

In the present study, we investigated the participation of chemical mediators in the development of experimental allergic conjunctivitis in rats. Cetirizine (a histamine H1 receptor antagonist), ramatroban (a thromboxane A2 (TXA2) receptor antagonist) and zafirlukast (a cysteinyl leukotrienes (cys-LTs) receptor antagonist) were orally administered from day 14 to day 42 during repeated topical antigen challenge. An increase in reactivity to antigen- and histamine-induced eye scratching behavior was observed by topical sensitization in sensitized rats. Although increased reactivity to antigen was not influenced by cetirizine, ramatoroban and zafirlukast, increased reactivity to histamine was significantly inhibited by ramatroban. The development of conjunctival edema was also observed for topical sensitization. Cetirizine caused no inhibition of the development of conjunctival edema, but ramatroban and zafirlukast inhibited the development of conjunctival edema. In addition, the number of eosinophils in the conjunctiva was increased by topical sensitization. Cetirizine had no significant effect on the increase in the number of eosinophils. However, ramatroban and zafirlukast were effective in inhibiting an increase in the number of eosinophils induced by topical sensitization. These results indicate that TXA2 is involved in increased histamine reactivity, and TXA2 and cys-LTs are associated with not only the conjunctival edema but also eosinophil infiltration during the development of experimental allergic conjunctivitis in rats.

Phenotypic alteration of neuropeptide-containing nerve fibres in seasonal intermittent allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) is the most common allergic disease affecting the respiratory tract. Next to inflammatory changes, the airway innervation plays an important modulatory role in the pathogenesis of the disease.

OBJECTIVE

To examine the participation of different neuropeptides in the human nasal mucosa of intermittent (seasonal) AR tissues in the allergic season.

METHODS

Immunohistochemistry for substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP) and neuropeptide tyrosine (NPY) was related to the characterization of inflammatory cells in tissues of patients with seasonal AR (n=18).

RESULTS

While there was a significant increase in the number of eosinophils present if compared with a control group, no changes occurred in mast cell numbers. Immunostaining was abundantly found in different nerve fibre populations of both groups. SP expression was significantly increased in mucosal nerve fibres of patients with intermittent (seasonal) AR. Also, significantly increased numbers of VIP- and NPY-immunoreactive nerve fibres were found in biopsies of rhinitis patients in comparison with sections of normal human nasal mucosa. In contrast, CGRP expression did not change significantly.

CONCLUSION

The increase of neuropeptide expression in mucosal nerve fibres indicates a major role of the autonomous mucosal innervation in the pathophysiology of intermittent (seasonal) AR.

Comparison of the combinations of fexofenadine-pseudoephedrine and loratadine-montelukast in the treatment of seasonal allergic rhinitis

BACKGROUND

Antihistamine-decongestant combinations are used routinely for the treatment of seasonal allergic rhinitis. Recently, the combination of an antihistamine and a leukotriene receptor antagonist has been shown to be efficacious.

OBJECTIVE

To compare the 2 combinations in the treatment of seasonal allergic rhinitis.

METHODS

This was a randomized, double-blind, double-dummy, parallel study in which patients with seasonal allergic rhinitis received either fexofenadine, 60 mg, and pseudoephedrine, 120 mg, twice daily, or loratadine, 10 mg, and montelukast, 10 mg, once daily, for 2 weeks. The Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) was completed at the beginning and end of the study. Patients recorded nasal symptoms and measured nasal peak inspiratory flow (NPIF) twice daily. Baseline measurements were obtained before initiation of treatment.

RESULTS

Compared with baseline, both treatments resulted in statistically and clinically meaningful reductions of overall and individual RQLQ domain scores (P < .01) except for the sleep domain, for which only loratadine-montelukast led to significant improvement. There was a significant reduction in total symptoms (P < or = .05) compared with baseline on most treatment days in patients receiving both combinations. When the change from baseline was analyzed, there were no statistically significant differences in total symptoms between fexofenadine-pseudoephedrine and loratadine-montelukast (median, -28.5 vs -22.5; P = .33). There was a significant improvement in NPIF from baseline on all treatment days in both groups (P < .05), with no significant difference between treatments.

CONCLUSIONS

Fexofenadine-pseudoephedrine and loratadine-montelukast have comparable efficacy in improving symptoms, RQLQ scores, and nasal obstruction in seasonal allergic rhinitis. The lack of improvement in sleep in the fexofenadine-pseudoephedrine group is probably related to insomnia, a known adverse effect of pseudoephedrine.

Targeting cysteinyl leukotrienes in patients with rhinitis, sinusitis and paranasal polyps

Leukotrienes have been known in the field of immunology since the 1930s. At that time they were referred to as the slow reacting substance of anaphylaxis. They were not, however, characterized until the 1980s, when they were noted to be formed during the breakdown of arachidonic acid by the enzyme 5-lipoxygenase. The leukotrienes consist of leukotriene (LT) A4, LTB4, LTC4, LTD4 and LTE4, so named because the molecule was originally isolated from leukocytes and therefore its carbon backbone contains three double bonds in series, which constitutes a trion. This structural information provided the key to the oxidative pathway of lipometabolism, known as the 5-lipoxygenase. Leukotrienes are classified as inflammatory mediators, and therefore they are produced by a number of cell types, particularly mast cells, eosinophils, basophils, macrophages and monocytes. With the identification of asthma, allergic rhinitis and paranasal sinusitis associated with inflammatory pathways, the leukotrienes have been implicated in the pathogenesis of these conditions and have become targets for therapeutic modulation. Leukotriene synthesis inhibitors have been used successfully in the treatment of patients with asthma where they have demonstrated the ability to induce bronchial dilatation, provide protection against broncho-provocation tests and significantly diminish symptoms. When it was serendipitously noted that patients who had concomitant nasal pathology also showed improvement, leukotriene synthesis inhibitors were used as adjuvant therapy in the management of patients with rhinitis, sinusitis and nasal polyposis. Preliminary studies have demonstrated improvements in nasal airflow and reduced recurrence of nasal polyps as noted by endoscopy and imaging studies. Leukotriene synthesis inhibitors therefore appear to be a novel treatment modality for patients with rhinitis, sinusitis and nasal polyps when used as adjunctive therapy.

Elevations of local leukotriene C4 levels during viral upper respiratory tract infections

BACKGROUND

One potential mechanism by which respiratory viruses trigger illness and complications is via the local elaboration of inflammatory mediators.

OBJECTIVE

To determine whether there is an increase in local leukotriene C4 (LTC4) levels during experimental infection with influenza A virus (FLU), rhinovirus (RV), or respiratory syncytial virus (RSV).

METHODS

Healthy adults were intranasally inoculated with a safety-tested strain of FLU (n = 29), RV (n = 16), or RSV (n = 21). Nasal lavage samples were collected, symptoms were recorded, and expelled nasal secretions were weighed before and then daily after challenge. Lavage samples were submitted for viral culture and assayed for LTC4 levels by radioimmunoassay. Serum antibody titers to the challenge viruses were assayed at baseline and 21 days after challenge.

RESULTS

All subjects were infected as evidenced by viral shedding and/or seroconversion. Following infection, significant increases (P < 0.05 by analysis of variance) in LTC4 levels were measured for each virus. Furthermore, there was a temporal association between the local LTC4 levels and the development of illness.

CONCLUSIONS

The results of this study, which used an adult experimental model, demonstrate elevations in locally produced LTC4 during respiratory infection with FLU, RV, and RSV. Future studies using antileukotriene agents may help elucidate the precise role of leukotrienes in mediating disease expression.

The role of leukotrienes in nasal allergy

OBJECTIVE

This review focuses on the role of cysteinyl leukotrienes (cysLTs) in nasal allergy. The purpose was to provide knowledge of the role of cysLTs in the pathophysiology of nasal allergy and the role of antileukotrienes in the treatment of nasal allergies. Materials and methods We conducted a literature review.

RESULTS

The proinflammatory effects of cysLTs have been well described in asthma. Antileukotrienes have proved to be an effective anti-inflammatory treatment for asthma patients. Similar to pathogenesis of asthma, cysLTs exert potent inflammatory effects in the upper airways and play a role in the pathogenesis of allergic rhinitis and other nasal allergies.

CONCLUSION

Antileukotriene treatment appears to be beneficial in nasal allergies. Allergic rhinitis is a complex, IgE-mediated inflammatory disease of the upper airways. It is the most common allergic disease, occurring in 10% to 30% of adults and up to 30% of children. It may be perennial or seasonal. Sneezing, itching, watery rhinorrhea, and nasal obstruction are classic symptoms. It may impair cognition, school/work performance and productivity, behavior, mood, and quality of life. On physical examination, clear secretions, nasal congestion, pink-bluish nasal mucosa, the allergic salute, and allergic shiners may be detected. Allergic rhinitis is a common comorbid condition with asthma, sinusitis, otitis media, nasal polyposis, and respiratory infections.

Nasal blockage and urinary leukotriene E4 concentration in patients with seasonal allergic rhinitis

BACKGROUND

Cysteinyl-leukotrienes have been reported to have a primary role in the induction of nasal blockage of allergic rhinitis. However, there has been little experimental evidence that substantiates the relationship between nasal blockage severity and urinary leukotriene E4 (U-LTE4) concentration in patients with seasonal allergic rhinitis (SAR).

METHODS

The concentrations of urinary mediators in 20 SAR patients were measured using an enzyme immunoassay to determine the relationship between nasal blockage severity and U-LTE4 concentration in patients with SAR.

RESULTS

The basal U-LTE4 concentration was significantly higher in SAR patients with severe nasal blockage than in those with mild nasal blockage and in healthy control subjects. Although U-LTE4 concentrationwas significantly higher in patients with both asthma and SAR than in SAR patients with mild nasal blockage, no significant difference in the U-LTE4 concentration between patients with both asthma and SAR and SAR patients with severe nasal blockage was found. There was a significant correlation between U-LTE4 and urinary 9alpha11beta-prostoglandin F2 (9alpha11betaPGF2) concentrations (rs = 0.51, P = 0.02) in SAR patients.

CONCLUSIONS

Although specific sites and cells of cysteinyl-leukotriene biosynthesis could not be determined in this study, severe nasal blockage is associated with the increased excretion level of U-LTE4.

The role of leukotriene inhibitors in patients with paranasal sinus disease

Leukotrienes are inflammatory mediators that are known as the slow-reacting substance of anaphylaxis produced by a number of cell types including mast cells, eosinophils, basophils, macrophages, and monocytes. Synthesis of these mediators results from the cleavage of arachidonic acid in cell membranes, and they exert their biologic effects by binding and activating specific adaptors. This occurs in a series of events that lead to contraction of the human airway smooth muscle, chemotaxis, and increased vascular permeability. These effects have led to their important role in the diseases of asthma, allergic rhinitis, and possible paranasal sinusitis with the formation of nasal polyps. Because these agents lead to the production of symptoms in patients that are asthmatic, the use of leukotriene enzyme inhibitors, particularly montelukast, and zafirlukasts seem appropriate. These classes of drugs can block the binding of leukotrienes to CysLT(1) receptors. Zileuton is a 5-lipoxygenase inhibitor that prevents the formation of leukotrienes and can also result in the prevention of leukotriene activity. Demonstrated efficacy in these patients in a number of studies has also suggested their role in inhibiting nasal symptoms in asthmatic patients. In addition, it has been suggested by serendipitous observations that many of the aspirin-intolerant patients have nasal polyps and that treatment with the leukotriene inhibitors has resulted in improvement and resolution of the polyps. Therefore, these agents may also play a role in patients afflicted with chronic sinusitis with concomitant nasal polyposis. These papers are discussed in detail because this form of therapy may represent a novel way to treat patients with this malady in addition to or in lieu of surgical treatment and steroid therapy.

Effects of fexofenadine on the early response to nasal allergen challenge

BACKGROUND

Previous studies using nasal allergen challenge models have shown that terfenadine, an H1 antihistamine, inhibits histamine release during the early response to allergen provocation. Fexofenadine, the active metabolite of terfenadine, has strong H1-antihistaminic activity and no cardiac effects. Clinical studies have documented the efficacy of fexofenadine in the treatment of allergic rhinitis.

OBJECTIVE

To determine whether fexofenadine, like terfenadine, inhibits histamine and tryptase release during the early allergic response.

METHODS

Randomized, double blind, placebo-controlled, two-way crossover study in 20 subjects with seasonal allergic rhinitis, out of their allergy season (median age 27.5 years, 13 males and 7 females). Subjects were medicated with either placebo or fexofenadine 180 mg orally daily for 1 week followed by nasal challenge with allergen. After each challenge, sneezes and nasal symptoms were recorded, and a nasal lavage was obtained for the assay of albumin, an indicator of vascular permeability, and histamine and tryptase, indicators of mast cell degranulation.

RESULTS

When patients were on placebo, allergen challenges led to significant increases in all measured parameters compared with the sham challenges with diluent. Treatment with fexofenadine resulted in inhibition of allergen-induced symptoms and increased vascular permeability, but not the release of histamine and tryptase.

CONCLUSION

Fexofenadine is an effective H1 antihistamine, but in contrast to its parent compound, terfenadine, it does not affect the release of the mast cell mediators histamine and tryptase.

Expression and localization of the cysteinyl leukotriene 1 receptor in human nasal mucosa

BACKGROUND

The cysteinyl leukotrienes (CysLT) are lipid mediators that have been implicated in the pathogenesis of allergic diseases. Pharmacological studies using CysLTs indicate that two classes of receptors, named CysLT1 and CysLT2 receptor, exist. The former is sensitive to the CysLT1 antagonist currently used to treat asthma and allergic rhinitis. Recently, the cDNA for human CysLT1 and CysLT2 receptor have been cloned, making it now possible to study the gene expression of CysLTs receptors.

OBJECTIVE

We have used reverse transcription and polymerase chain reaction (RT-PCR) to study the gene expression of CysLT1 and CysLT2 receptor and in situ hybridization to determine the distribution of CysLT1 receptor mRNA in human nasal mucosa. In addition, the distribution of the CysLT1 receptor protein was studied by immunohistochemistry.

METHODS

Human turbinates were obtained after turbinectomy from six patients with nasal obstruction refractory to medical therapy. Total RNA was isolated from human nasal mucosa and both CysLT1 and CysLT2 receptor mRNA was detected in these tissues by using RT-PCR. For in situ hybridization study of human nasal mucosa, we used biotin-labelled oligonucleotides probes encoding human CysLT1 receptor cDNA. To identify the cells expressing the CysLT1 receptor protein, double immunostaining was performed by using anti-CysLT1 receptor antibody and monoclonal antileucocyte antibodies.

RESULTS

RT-PCR analysis of total nasal RNA demonstrated the expression of both CysLT1 receptor and CysLT2 receptor mRNA. In situ hybridization indicated high levels of CysLT1 receptor hybridization in blood vessels and the interstitial cells, but a sparse signal in airway epithelium and submucosal glands. The immunohistochemical studies revealed that anti-CysLT1 receptor antibody labelled eosinophils, mast cells, macrophages, neutrophils and vascular endothelial cells in the nasal mucosa.

CONCLUSION

The results may have an important clinical implication and also promote further investigation of the regulation of CysLT1 receptor in health and disease.

Efficacy and tolerability of montelukast alone or in combination with loratadine in seasonal allergic rhinitis: a multicenter, randomized, double-blind, placebo-controlled trial performed in the fall

BACKGROUND

Histamine and cysteinyl leukotrienes seem to be important mediators of allergic rhinitis.

OBJECTIVE

This multicenter, randomized, double-blind, parallel-group, placebo-controlled trial evaluated the effectiveness and tolerability of montelukast, loratadine, and combination therapy with montelukast and loratadine for treating patients with fall seasonal allergic rhinitis.

METHODS

After a 1-week, single-blind, placebo run-in period, 907 male and female patients aged 15 to 82 years were randomized to 1 of 4 treatments: montelukast 10 mg (n = 155), loratadine 10 mg (n = 301), combination montelukast 10 mg and loratadine 10 mg (n = 302), or placebo (n = 149), administered once daily at bedtime for 2 weeks. The primary endpoint was the daytime nasal symptoms score (mean of congestion, rhinorrhea, pruritus, and sneezing).

RESULTS

Mean symptom scores at baseline were similar for the four treatment groups. For each of the three active treatments, the difference was significant for the mean change from baseline compared with placebo (P < or = 0.001). However, the effect of montelukast/loratadine compared with loratadine alone, the primary comparison, was not significantly different. Differences for each therapy alone compared with placebo were also significant for most secondary endpoints, including nighttime symptom scores, eye symptoms scores, and rhinitis-specific quality of life. Differences for montelukast/loratadine compared with each therapy alone generally showed numerical superiority, and a few endpoints showed differences that were statistically significant. All active treatments showed a safety profile generally similar to placebo.

CONCLUSIONS

Montelukast alone or in combination with loratadine is well tolerated and provides clinical and quality-of-life benefits for patients with seasonal allergic rhinitis.

Histamine H1 receptors are involved in mouse nasal allergic responses: a demonstration with H1 receptor-deficient mice

The role of histamine H1 receptors in nasal allergic symptoms (sneezing and nasal rubbing) were studied using histamine H1 receptor-deficient mice. Intranasal instillation of histamine solution resulted in significant increases in sneezing and nasal rubbing in wild-type mice, whereas no increases were observed in histamine H1 receptor-deficient mice. The histamine H1 receptor agonist 2-pyridylethylamine induced sneezing and nasal rubbing in a dose-dependent-manner in wild-type mice, but no such increase was found in histamine H1 receptor-deficient mice. On the other hand, the histamine H2 receptor agonist dimaprit did not increase sneezing and nasal rubbing in wild-type mice. Histamine H1 receptor antagonists such as chlorpheniramine and epinastine significantly inhibited nasal allergic symptoms caused by histamine, but the histamine H2 receptor antagonists cimetidine and famotidine showed no effect. No additional effects were observed by combined use of chlorpheniramine and cimetidine or famotidine compared with cimetidine or famotidine alone. These results suggested that histamine H1 receptors play an important role in nasal allergy symptoms induced by histamine.

The role of leukotriene inhibitors in allergic rhinitis and paranasal sinusitis

Leukotrienes are inflammatory mediators that are known as the slow-reacting substance of anaphylaxis produced by a number of cell types, including mast cells, eosinophils, basophils, macrophages, and monocytes. Synthesis of these meditators in the text result from the cleavage of arachidonic acid in cell membranes, and exert their biologic effects by binding and activating specific adaptors. This occurs in a serious of events that lead to contraction of the human airway smooth muscle, chemotaxis, and increased vascular permeability. These effects have lead to their important role in the diseases of asthma, allergic rhinitis, and possible paranasal sinusitis with the formation of nasal polyps. Since these agents lead to the production of symptoms in patients who are asthmatic, the use of leukotriene enzyme inhibitors, particularly montelukast, zafirlukasts seem appropriate.

Rhinitis, sinusitis and asthma: one linked airway disease

Understanding the relationship between upper and lower airways has greatly increased through epidemiological and pharmacological studies. Scientific evidence supports the concept that rhinosinusitis and asthma may be the expression of an inflammatory process which appears in different sites of the respiratory tract at different times. The implications are not only academic but are important for diagnostic and therapeutic purposes.

Current treatment of asthma--focus on leukotrienes

Since their identification in 1979, the cysteinyl leukotrienes (cysLTs) have been shown to be prominent in many inflammatory conditions, including asthma, allergic rhinitis, rheumatoid arthritis, psoriasis, cystic fibrosis and inflammatory bowel disease. They are potent pro-inflammatory agents, as well as causing bronchoconstriction, and undoubtedly have a role in asthma. The cysLTs are products of arachidonic acid metabolism and have been shown to have effects via a cysteinyl leukotriene receptor (CysLTR1) on vascular permeability, mucus production, chemotaxis and bronchial smooth muscle. Their detection in certain body fluids in allergic, aspirin-sensitive and exercise-induced asthma is well documented and potential roles in pathogenesis, proposed. The development of agents affecting production or action offers an exciting new approach to the treatment of asthma. Two approaches to antileukotriene therapy have been developed: blocking their production by inhibiting the action of 5-lipoxygenase enzyme or blocking the CysLTR1. Both approaches have been tried in studies in asthma and overall the results are encouraging, with a decrease in both daytime and nocturnal symptoms, a decrease in additional beta 2 agonist usage and improvement in lung function. The changes, however, are small in some studies. This may be a reflection of disease severity in the study subjects, but of note is a heterogeneity of response to these treatments that may be genetically determined. Antileukotriene therapy has been shown to have an effect in specific types of asthma where the role of cysLTs seems well established--aspirin-sensitive/intolerant asthma and exercise-induced asthma. Longer term studies are needed in other areas such as severe asthma and chronic persistent asthma in both children and adults to provide evidence for the appropriate placement of antileukotriene treatment in current asthma guidelines, in comparison with other established treatments.

A new model of allergic rhinitis in rats by topical sensitization and evaluation of H(1)-receptor antagonists

An animal model of chronic allergic rhinitis was developed by repeated local booster sensitization into the nasal cavity in sensitized rats. The severity of allergic rhinitis was assessed by determining the extent of two markers of nasal allergic symptoms (sneezing and nasal rubbing) after antigen challenge. The number of incidents of sneezing and nasal rubbing was markedly increased during intranasal instillation of antigen in sensitized rats. The PCA titers were also markedly elevated by intranasal sensitization. Some histamine H(1)-receptor antagonists such as chlorpheniramine, ketotifen, astemizole and epinastine inhibited the increase in antigen-induced nasal symptoms in a dose-related manner. Nasal rubbing was more potently inhibited by H(1)-receptor antagonists than sneezing. In conclusion, we developed a chronic allergic rhinitis model showing nasal symptoms in rats, and this model may be useful for evaluating the effects of drugs on allergic rhinitis.

Evaluation of treatment response in patients with seasonal allergic rhinitis using domiciliary nasal peak inspiratory flow

BACKGROUND

Measurement of domiciliary nasal peak inspiratory flow rate (PIFR) may have a role in the objective assessment of treatment response in seasonal allergic rhinitis (SAR).

OBJECTIVE

We wished to evaluate the relationship between domiciliary measurement of nasal PIFR and a variety of symptoms associated with rhinitis.

METHODS

Thirty-eight nonasthmatic patients, mean age (SEM) 30 years (1.4), with symptomatic SAR were evaluated in a placebo-controlled, single-blind, double-dummy, three way parallel group study. Patients received oral cetirizine 10 mg once daily and were randomized to receive, in addition, either: (i) intranasal mometasone furoate 200 microgram (n = 14); (ii) oral montelukast 10 mg (n = 11); or (iii) placebo (n = 13). All treatments were given once daily for 4 weeks and were preceded by a 1 week placebo period. Domiciliary diary cards were used to record morning (am) and evening (pm) domiciliary nasal PIFR and symptom (nasal, eye, throat) scores and impact on daily activity. A total daily symptom score was then calculated from the sum of these separate symptom scores.

RESULTS

Baseline values for symptom scores and PIFR after placebo run-in were not significantly different when comparing the three groups. After 4 weeks of active treatment, there were significant (P < 0.05) improvements in nasal symptoms, total daily symptoms and PIFR with all treatments, with there being no significant confounding effect of pollen count, when analysed as a covariate. There were significant (P < 0.01) correlations for nasal symptom scores vs PIFRam (r = - 0.51) and PIFRpm (r = - 0.56), and similarly for daily activity vs PIFRam (r = - 0.42) and PIFRpm (r = - 0.48).

CONCLUSIONS

These results suggest that domiciliary measurements of nasal peak flow correlate significantly with symptoms of seasonal allergic rhinitis and may therefore be a potentially useful objective short-term marker of treatment response.

Concomitant montelukast and loratadine as treatment for seasonal allergic rhinitis: a randomized, placebo-controlled clinical trial

BACKGROUND

Nasal challenge studies have suggested histamine and cysteinyl leukotrienes are important proinflammatory mediators in allergic rhinitis. This study was designed to determine the efficacy of montelukast, a cysteinyl leukotriene receptor antagonist, administered alone or concomitantly with loratadine, an H(1)-receptor antagonist, in seasonal allergic rhinitis.

OBJECTIVE

The purpose of this study was to determine the effect of concomitant use of montelukast and loratadine in the treatment of seasonal allergic rhinitis.

METHODS

In this multicenter (N = 12) double-blind, randomized, parallel-group, placebo-controlled 2-week trial, 460 men and women, aged 15 to 75 years, with spring seasonal allergic rhinitis were randomly allocated to receive 1 of the following 5 treatments: montelukast 10 or 20 mg, loratadine 10 mg, montelukast 10 mg with loratadine 10 mg, or placebo, once daily in the evening. The primary end point was daytime nasal symptoms score (average of congestion, rhinorrhea, itching, and sneezing). Other end points were eye symptoms, nighttime symptoms, individual daytime nasal symptoms, global evaluations (patient's and physician's), and rhinoconjunctivitis quality-of-life scores.

RESULTS

Concomitant montelukast with loratadine improved the primary end point significantly (P <.001) compared with placebo and each agent alone. Compared with placebo, montelukast with loratadine also significantly improved eye symptoms, nighttime symptoms, individual daytime nasal symptoms, global evaluations, and quality of life. Montelukast alone and loratadine alone caused modest improvements in rhinitis end points. All treatments were similarly well tolerated.

CONCLUSIONS

Concomitant montelukast with loratadine provided effective treatment for seasonal allergic rhinitis and associated eye symptoms with a safety profile comparable with placebo.

Dense mapping of chromosome 12q13.12-q23.3 and linkage to asthma and atopy

BACKGROUND

Asthma is a complex disease characterized by a high prevalence of allergic diathesis and the almost ubiquitous presence of upper airway disease (eg, rhinitis). Previously, we observed linkage of asthma among Afro-Caribbean families to markers in chromosome 12q, which contains a number of genes encoding for products closely related to allergic airway inflammation and disease.

OBJECTIVE

To identify susceptibility loci in chromosome 12q contributing to the genetics of upper and lower airway diseases and to expand the region to include genes encoding IFN-gamma (IFNG ) and one of the signal transducers and activators of transcription (STAT6 ), we conducted further linkage studies among 33 multiplex families.

METHODS

We characterized 528 subjects from Barbados for asthma; 82% were characterized for allergic rhinitis. Two-point and multipoint linkage analysis of 22 microsatellite markers (spanning approximately 79 centimorgan) was performed.

RESULTS

Affected sib-pair analysis revealed significant evidence for linkage to asthma over approximately 30 cM (P <.05 to.002), with the best evidence for linkage at a CA repeat polymorphism in the first intron of IFNG in 12q21.1 (P =.002). Evidence of linkage to allergic rhinitis was observed in the same region (D12S313, P = 0.006, and IFNGCA, P =.01, respectively). Multipoint linkage analysis also provided evidence for linkage to asthma, with the best nonparametric linkage analysis score at D12S326 (nonparametric linkage score = 3.8, P =.0008). Modest evidence for linkage to allergic rhinitis was observed next to D12S326 at D12S1052 (P =.036).

CONCLUSIONS

Our findings suggest that (1) one or more loci in the chromosome 12q13. 12-q23.3 region are contributing to the expression of the clinical phenotype asthma and the strongest evidence for linkage is in a region near the gene encoding IFNG and (2) a susceptibility locus for both asthma and allergic rhinitis maps to this region.

Involvement of cysteinyl leukotrienes in biphasic increase of nasal airway resistance of antigen-induced rhinitis in guinea pigs

We examined the effect of a specific cysteinyl leukotriene (LT) receptor antagonist, 4-oxo-8-[4-(4-phenylbutoxy)benzoylamino]-2-(tetrazol-5-yl)-4 H-1-benzopyran hemihydrate (pranlukast), on a novel model of allergic rhinitis induced by repeated intranasal ovalbumin challenge in actively sensitized guinea pigs. Repeated intranasal ovalbumin challenge caused a biphasic increase of nasal airway resistance, peaking 0.5 and 4 h after the final challenge. The early-phase response was accompanied by an increase in sneezing and nasal secretion, while that in the late phase was associated with edema and eosinophil infiltration of the nasal mucosa. Analysis of nasal lavage fluid showed that cysteinyl LTs increased in both phases. Pranlukast, when administered 1 h before every ovalbumin challenge, dose-dependently suppressed the increase of nasal airway resistance in the early- and late phase with evidence of histopathological improvements in the late phase. Pranlukast, however, failed to suppress sneezing and nasal secretion. We suggest that cysteinyl LTs play an important role in allergic rhinitis especially in the nasal obstruction due to edema of the nasal mucosa membrane.

Clinical manifestations of the release of histamine and other inflammatory mediators

This article reviews the symptoms that are characteristic of the early- and late-phase allergic reaction. Each of the cardinal symptoms of seasonal allergic rhinitis (sneezing, pruritus, rhinorrhea, congestion) is discussed, as is the role of various chemical mediators in the expression of these clinical manifestations.

Mediators of inflammation and the inflammatory process

A complex interplay of inflammatory cells and chemical mediators is responsible for allergic inflammation. It is now understood that the allergic reaction consists of an early-phase response involving mast cell degranulation with the release of histamine and a late-phase response characterized by the migration of inflammatory cells. This review provides a summary of the early- and late-phase events associated with allergic inflammation and an overview of the principal chemical mediators involved in the inflammatory process.

Leukotriene-receptor antagonists

Leukotriene-receptor antagonists are the first novel class of antiasthma drugs to become available over the past three decades. They have an unique profile in that they are a hybrid of an anti-inflammatory and bronchodilator drug, and they can be taken as a tablet once or twice daily. The published data with leukotriene-receptor antagonists such as montelukast or zafirlukast show good antiasthmatic activity over a wide spectrum of asthma severity either as monotherapy or with inhaled steroids. Another potential spin-off of leukotriene-receptor antagonists is that they also seem to be effective in treating allergic rhinitis, which commonly coexists in patients with asthma. Here I overview the clinical pharmacology of leukotriene antagonists and appraise the published data from clinical trials, and look at the appropriate position of these agents in asthma management guidelines.

Leukotrienes C4 and D4 increase the ciliary beat frequency in human upper airway mucosa in vitro

It has been suggested that leukotrienes C4 (LTC4) and D4 (LTD4) released from upper respiratory mucosa influence mucociliary transport during allergic reactions. We studied the in vitro effects of leukotrienes C4 and D4 on the ciliary beat frequency (CBF) of human adenoid explants over a 5-hour period. Tissue explants were cultured at 35 degrees C in Minimum Essential Medium Eagle (MEM). The CBF was measured using phase contrast microscopy and microphotometry. Measurements of CBF were recorded in medium alone and in medium containing LTC4 or LTD4 at concentrations of 10(-8) and 10(-6) M. LTC4 and LTD4 increased CBF at concentrations of 10(-8) and 10(-6) M with increases of 20.51% +/- 2.69% and 29.84% +/- 4.06%, respectively. To determine the specificity of the LTC4 and LTD4 effects, the ciliated epithelium was treated with the specific leukotriene receptor antagonist LY-171,883 before administration of LTC4 and LTD4. LY-171,883 (10(-6) M) significantly inhibited the ciliostimulatory effects of both leukotrienes. Our findings indicate that LTC4 and LTD4 increase CBF in vitro by activation of the LTD4 receptor.