Pathogenesis of allergic rhinitis

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.

Matrix metalloproteinases and their inhibitors in the nasal mucosa of patients with perennial allergic rhinitis

BACKGROUND

Allergic rhinitis and asthma show many similarities in their epithelial and inflammatory responses to allergens. However, one notable difference is that disruption and desquamation of the epithelium is a characteristic feature of asthma, whereas in perennial allergic rhinitis the epithelium is intact and thickened. One reason for this might be differing expression of matrix metalloproteinases (MMPs) or their inhibitors (TIMPs). There are few published data on the presence of MMPs or TIMPs in the nasal mucosa in rhinitis.

OBJECTIVE

The purpose of this study was to investigate MMP and TIMP mRNA and protein in nasal mucosa from subjects with perennial allergic rhinitis and from nonrhinitic control subjects.

METHODS

Biopsy specimens of nasal mucosa were taken from 10 well-characterized subjects with perennial allergic rhinitis and 10 nonrhinitic control subjects. MMP and TIMP mRNA was quantified through use of competitive RT-PCR, and protein was detected by means of Western blotting and ELISA.

RESULTS

TIMP-1 mRNA and TIMP-2 mRNA were present in nasal samples, but there was no significant difference between the 2 groups. Only small amounts of MMP-1, -2, -3, and -9 mRNA were detected in the same samples. The corresponding proteins were detected by means of Western blotting. TIMP-1 protein and TIMP-2 protein were quantified in tissue homogenates; there was no significant difference between the 2 groups.

CONCLUSION

Our studies have demonstrated the presence of large amounts of TIMP-1 and TIMP-2 mRNA and protein in nasal mucosa. There is no upregulation of MMPs or changes in TIMP expression in the nasal mucosa of patients with allergic rhinitis.

IL-4 differentially regulates eotaxin and MCP-4 in lung epithelium and circulating mononuclear cells

To investigate the mechanisms of eosinophil recruitment in allergic airway inflammation, we examined the effects of interleukin (IL)-4, a Th2-type cytokine, on eotaxin and monocyte chemoattractant protein-4 (MCP-4) expression in human peripheral blood mononuclear cells (PBMCs; n = 10), in human lower airway mononuclear cells (n = 5), in the human lung epithelial cell lines A549 and BEAS-2B, and in human cultured airway epithelial cells. IL-4 inhibited eotaxin and MCP-4 mRNA expression induced by IL-1 beta and tumor necrosis factor-alpha in PBMCs but did not significantly inhibit expression in epithelial cells. Eotaxin and MCP-4 mRNA expression was not significantly induced by proinflammatory cytokines in lower airway mononuclear cells. IL-1 beta-induced eotaxin and MCP-4 protein production was also inhibited by IL-4 in PBMCs, whereas IL-4 enhanced eotaxin protein production in A549 cells. In contrast, dexamethasone inhibited eotaxin and MCP-4 expression in both PBMCs and epithelial cells. The divergent effects of IL-4 on eotaxin and MCP-4 expression between PBMCs and epithelial cells may create chemokine concentration gradients between the subepithelial layer and the capillary spaces that may promote the recruitment of eosinophils to the airway in Th2-type responses.

IgE levels are the same in chronic fatigue syndrome (CFS) and control subjects when stratified by allergy skin test results and rhinitis types

BACKGROUND

Chronic fatigue syndrome (CFS) has an uncertain pathogenesis. Allergies have been suggested as one cause.

OBJECTIVE

The aim of this study was to compare serum immunoglobulin (Ig)E in CFS and control subjects to determine whether IgE levels were elevated in CFS. This would be suggestive of increased atopy in CFS.

METHODS

IgE was measured by quantitative ELISA (sandwich) immunoassay in 95 CFS and 109 non-CFS control subjects. Subjects were classified by positive or negative allergy skin tests (AST) and rhinitis questionnaires (rhinitis score, RhSc) into four rhinitis types: nonallergic rhinitis (NAR with positive RhSc and negative AST); allergic rhinitis (AR with positive AST and RhSc); atopic/no rhinitis (AST positive/RhSc negative); and nonatopic/no rhinitis (both AST and RhSc negative) subjects.

RESULTS

IgE was not significantly different between control (128 +/- 18 IU/mL, mean +/- SEM) and CFS (133 +/- 43 IU/mL) groups, or between control and CFS groups classified into the four rhinitis types. IgE was significantly higher in subjects with positive AST whether or not they had positive RhSc or CFS symptoms.

CONCLUSIONS

Elevated IgE and positive AST indicate allergen sensitization, but are not necessarily indicators of symptomatic allergic diseases. There was no association between IgE levels and CFS, indicating that atopy was probably not more prevalent in CFS. Therefore, TH2-lymphocyte and IgE-mast cell mechanisms are unlikely causes of CFS.

An open audit of montelukast, a leukotriene receptor antagonist, in nasal polyposis associated with asthma

BACKGROUND

Nasal polyposis occurs frequently in patients with intrinsic asthma, especially in those who are aspirin sensitive. It can be difficult to treat effectively, even with surgery and regular topical intranasal corticosteroids many patients are still symptomatic.

OBJECTIVE

To investigate the response to montelukast, a leukotriene D4 receptor antagonist, as an add-on therapy to topical and inhaled corticosteroids in patients, both aspirin sensitive (AS) and aspirin tolerant (AT), with nasal polyposis and asthma.

METHODS

Nasal polyposis symptoms were assessed by visual analogue scales; nasal polyps were assessed by nasendoscopy and via the measurement of nasal volumes by acoustic rhinometry. The nasal airway was assessed by nasal inspiratory peakflow (NIPF). Asthma was monitored using symptom scores and peak expiratory flow measurements. Aspirin sensitivity was assessed by history together with intranasal lysine aspirin challenge. Upper and lower airway nitric oxide measurements were made before and during treatment.

RESULTS

Clinical subjective improvement in nasal polyposis occurred in 64% AT (P < 0.01), patients and 50% AS patients (P > 0.05); asthma improvement in 87% AT and 61% AS patients (P < 0.05 for both). Objective changes in peak flow occurred only in AT patients (P < 0.05). Acoustic rhinometry, nasal inspiratory peak flow and nitric oxide levels did not change significantly in any group, however, correlations were seen between nitric oxide levels and polyp scores and between nitric oxide levels and acoustic rhinometry changes. Improvement on montelukast therapy was not associated with any of the following variables: age, sex, skin prick test positivity, disease duration or aspirin sensitivity. (P > 0.05 for all).

CONCLUSION

The findings are consistent with a subgroup of nasal polyps/asthma patients in whom leukotriene receptor antagonists are effective. This is not related to aspirin sensitivity. Further placebo-controlled studies need to be undertaken.

Doppler echocardiographic evaluation of pulmonary arterial pressure in children with allergic rhinitis

In children, persistent upper airway obstruction may lead to increased pulmonary arterial pressure (PAP). Allergic rhinitis (AR) is one of the frequent cause of persisting upper airway obstruction by nasal blockage in childhood. Regular use of nasal topical corticosteroids are effective in reducing nasal blockage and obstruction. However, whether symptomatic children with AR have increased PAP and curative effect of topical steroids are not known. The aims of this study were to clarify whether children having active symptoms of AR have increased PAP and to investigate the curative effect of reducing nasal obstruction by topical corticosteroids. Twenty-three children, aged between 5 and 16, diagnosed as AR, consisted of 17 seasonal AR (SAR) and seven perennial AR (PAR), were included in the study. Nineteen age and sex matched healthy children were received as controls. PAP was measured by using Doppler echocardiography in all subjects and symptom scores of AR were recorded in rhinitis group. After first evaluation, nasal steroid, budesonid, was given to rhinitis group for three months. Mean systolic PAP was 33.4+/-3.1 for children with AR mmHg and 23.6+/-4.3 mmHg for the control group. The difference was statistically significant (P<0.05). Mean systolic PAP of children with PAR was significantly higher than children with SAR (P<0.05). In rhinitis group, mean PAP decreased significantly after relief of upper airway obstruction by nasal corticosteroid therapy to normal level of 24.9+/-3.6 mmHg (P<0.05). Our results showed that children with AR may have significantly higher PAP than healthy subjects and decreased to normal levels after relieving nasal blockage by nasal corticosteroids. Nevertheless, Doppler echocardiography is a safe, non-invasive and practical tool for cardiac investigation of children with AR. Therefore, in symptomatic period, evaluation of PAP of children with AR by using Doppler echocardiography may be useful in the planning and following of their therapy.

Mode of action of intranasal corticosteroids

The mode of action of intranasal corticosteroids (INCS) is complex. It is not known whether INCS penetrate the nasal mucosa or act on target cells; however, their low systemic activity supports the concept of local action on nasal mucosa. This local effect can nonetheless influence a variety of inflammatory cells and their mediators such as epithelial cells, lymphocytes, basophils, mast cells, and Langerhans cells. Corticosteroid-induced inhibition of immunoglobulin E-dependent release of histamine is a possible but unproven mode of action. Epithelial cells are an important target for corticosteroids, and INCS concentration is high at the epithelial surface. INCS may combine with the corticosteroid receptors in epithelial cells, which are then expelled into the airway lumen together with the dead epithelial cells or migrating inflammatory cells. A reduced influx of mediator cells may explain some of the effects of INCS on rhinitis symptoms, but it cannot explain all of the effects because INCS also reduce the early-phase sneezing and rhinorrhea after an allergen challenge outside the pollen season. In this situation, the number of surface mast cells/basophils is very low, as it is in the absence of allergic rhinitis. The mechanism by which INCS treatment of allergic rhinitis reduces itching, sneezing, and rhinorrhea, the characteristic symptoms of an early-phase response involving mast cell release of histamine, remains to be determined. Studies should be conducted to characterize the broad range of mechanisms by which INCS produce their therapeutic effects in allergic rhinitis.

Mechanisms of allergic rhinitis

The pathogenesis of allergic rhinitis can be better appreciated by understanding the numerous protective mechanisms available for mucosal defense. The system of TH2 lymphocytes, IgE production, mast cell degranulation, eosinophil infiltration, and resident cell responses are central to our understanding and treatment of allergic rhinitis. Histamine remains preeminent in causing the cardinal symptoms of the immediate allergic reaction: itching, watery discharge, and nasal swelling. Recruitment and activation mechanisms responsible for the late-phase allergic response are also reviewed.

Evidence-based treatment of allergic rhinitis

Allergic rhinitis is an extremely common disease worldwide, affecting 10% to 50% of the population. An increasing prevalence of allergic rhinitis over the past decades and its frequent association with asthma have raised concerns about treating the disease appropriately. New knowledge of the pathophysiologic mechanisms underlying allergic inflammation of the airways has resulted in the development of newer and better therapeutic strategies. This review focuses on evidence-based treatment of allergic rhinitis, highlighting the most recent international consensus and evidence-based guidelines on allergic rhinitis.

Cytokine expression during allergen-induced late nasal responses: IL-4 and IL-5 mRNA is expressed early (at 6 h) predominantly by eosinophils

The production of TH2-type cytokines [interleukin-4 (IL-4) and IL-5] and tissue eosinophilia are characteristic features of allergic diseases. It was previously reported that at 24 h after allergen provocation, CD3+ T-lymphocytes were the principal cell source of IL-4 and IL-5 mRNA transcripts in both atopic asthma and rhinitis. To investigate whether IL-4 and IL-5 mRNA are expressed earlier during late nasal responses and if so, which cell(s) are responsible. Nasal biopsies were obtained at 6 h after nasal allergen challenge and following a control challenge with the allergen diluent. Sections were immunostained for T-lymphocytes (CD3+, CD4+) and eosinophils (EG2+). In situ hybridization was used to detect the number of cells expressing messenger RNA (mRNA) for IL-4 and IL-5. In patients with allergic rhinitis, eosinophils (EG2+ cells P = 0. 006) but not T- cells (CD3+ cells) increased in the nasal mucosa at 6 h after allergen challenge. The number of cells expressing IL-4 mRNA (P = 0.01) and IL-5 mRNA (P = 0.05) also increased at 6 h. Co-localization studies showed that 76% of IL-4 mRNA+ cells and 77% of IL-5 mRNA+ cells were eosinophils, whereas at this time point, T-cells and mast cells accounted for </=5% of mRNA expression; the identity of the remaining 20% of IL-4 and IL-5 mRNA+ cells was not determined. By use of immunohistology, cytokine protein expression at 6 h was confirmed for IL-4 but not for IL-5. No increases in T-cells, eosinophils or cytokine expression were detected in non-atopic subjects. Eosinophils represent an early source of IL-4 which may contribute to TH2-type responses during late nasal responses and ongoing allergic rhinitis.

Probiotics in the management of atopic eczema

BACKGROUND

Over the last two decades the incidence of allergic diseases has increased in industrialized countries, and consequently new approaches have to be explored.

OBJECTIVE

The potential of probiotics to control allergic inflammation at an early age was assessed in a randomized double-blind placebo-controlled study.

METHODS

A total of 27 infants, mean age 4.6 months, who manifested atopic eczema during exclusive breast-feeding and who have had no exposure to any infant or substitute formula were weaned to probiotic-supplemented, Bifidobacterium lactis Bb-12 or Lactobacillus strain GG (ATCC 53103), extensively hydrolysed whey formulas or to the same formula without probiotics. The extent and severity of atopic eczema, the growth and nutrition of infants, and concentrations of circulating cytokines/chemokines and soluble cell surface adhesion molecules in serum and methyl-histamine and eosinophilic protein X in urine were determined.

RESULTS

The SCORAD score reflecting the extent and severity of atopic eczema was 16 (7-25) during breast-feeding, median (interquartile range). After 2 months, a significant improvement in skin condition occurred in patients given probiotic-supplemented formulas, as compared to the unsupplemented group; chi(2) = 12.27, P = 0.002. SCORAD decreased in the Bifidobacterium lactis Bb-12 group to 0 (0-3.8), and in the Lactobacillus GG group to 1 (0.1-8.7), vs unsupplemented 13.4 (4.5-18.2), median (interquartile range), in parallel with a reduction in the concentration of soluble CD4 in serum and eosinophilic protein X in urine.

CONCLUSION

The results provide the first clinical demonstration of specific probiotic strains modifying the changes related to allergic inflammation. The data further indicate that probiotics may counteract inflammatory responses beyond the intestinal milieu. The combined effects of these probiotic strains will guide infants through the weaning period, when sensitization to newly encountered antigens is initiated. The probiotic approach may thus offer a new direction in the search for future foods for allergy treatment and prevention strategies.

Upregulation of nasal mucosal eotaxin in patients with allergic rhinitis during grass pollen season: effect of a local glucocorticoid

BACKGROUND

Allergic rhinitis is a common disease characterized by infiltration of eosinophils into the nasal mucosa during the periods of symptoms. Among chemokines, which attract cells to the site of inflammation, eotaxin is relatively specific for eosinophils.

OBJECTIVE

We examined the influence of grass pollen season on nasal eotaxin expression in patients with seasonal allergic rhinitis, as well as the effect of a nasal glucocorticoid on this eotaxin expression.

METHODS

Nineteen patients with allergic rhinitis received treatment with either nasal beclomethasone (400 microgram/day) or placebo over a grass pollen season. In these patients, nasal biopsies were taken prior to and during the peak of the pollen season and stained immunohistochemically for eotaxin and EG2 + eosinophils. Five healthy subjects served as controls and gave nasal biopsies once prior to the pollen season.

RESULTS

Prior to pollen season, there was no significant difference in nasal eotaxin expression between patients with allergic rhinitis and healthy subjects. Grass pollen season induced significant increase in eotaxin expression in placebo-treated (P = 0.04; n = 9) but not in beclomethasone-treated rhinitis patients (P = 0.8; n = 10). During peak grass pollen season, the eotaxin expression in placebo-treated patients was significantly higher compared with healthy subjects outside season (P = 0.03). There was no significant correlation between the expression of eotaxin and the number of EG2 + eosinophils in nasal mucosa. The serum levels of eotaxin in rhinitis patients remained stable over the pollen season.

CONCLUSION

Expression of eotaxin in nasal mucosa of grass-pollen allergic rhinitis patients is upregulated during pollen season and treatment with a nasal glucocorticoid protects against this upregulation.

A mechanism of antigen-induced mucus production in nasal epithelium of sensitized rats. A comparison with lipopolysaccharide-induced mucus production

We produced ovalbumin (OVA)-sensitized rats as an animal model of nasal allergy. Intranasal instillation of OVA induced hypertrophic and metaplastic changes of goblet cells in nasal epithelium of OVA- sensitized rats. Intraepithelial mucosubstance in nasal mucosa increased significantly at 24 h after 3 or 7 d of OVA instillation, accompanied by mucosal infiltration of eosinophils. The effects of H1-antagonist (d-chlorpheniramine malate), H2-antagonist (cimetidine), dexamethasone, indomethacin, cysteinyl leukotrienes (cysLTs)-antagonist (ONO1078), and antirat neutrophil antiserum on OVA-induced changes were examined. Mucus production was significantly inhibited by dexamethasone, and ONO1078, whereas eosinophil infiltration was significantly inhibited by H1-antagonist, dexamethasone, and anti-rat neutrophil antiserum. These results indicate that cysLTs (LTs C4, D4, and E4) may play an important role in antigen-induced mucus production, and that eosinophil infiltration does not relate to mucus production. Intranasal instillation of lipopolysaccharide (LPS) also induced intraepithelial mucus production, and it was significantly inhibited by dexamethasone, indomethacin, and antirat neutrophil antiserum; however, cysLTs antagonist had no effect on LPS-induced change. These results indicate that neutrophil and cyclooxygenase products are important in LPS-induced mucus production, and there are different mechanisms of mucus production between allergic inflammation and LPS stimulation.

Proliferative activity and cytometric characteristics in polyps of the nasal cavity and paranasal sinuses

Although several investigations have revealed the influence of cytokines, allergy, and environmental factors in polyp development, the etiology of nasal polyps is still unknown. To estimate the biology of this common disease the operative specimens of 50 patients who underwent surgery for polyps of the nasal cavity and the paranasal sinuses were examined; of these, 10 patients had recurrent disease and 23 patients had an allergy. The investigations included routine histology and quantitative DNA measurements, along with immunohistochemical identification of proliferation markers (i.e., MIB-1; proliferating cell nuclear antigen, PCNA). Histologically, most polyps revealed an infiltration with lymphocytes, eosinophilic granulocytes, and plasma cells. Twenty-five percent had a squamous metaplasia of the respiratory epithelium. Quantitative DNA analysis demonstrated diploid stemlines and lack of aneuploid cells with a DNA content exceeding 5c in most cases. Immunohistochemical detection of proliferation markers showed low proliferation rates in all cases. In 27 polyps no MIB-1 expression was detected, and in 7 polyps no PCNA expression was detected. The polyps of the 23 patients with proven allergic diathesis did not reveal higher scores for the parameters of DNA analysis (i.e., ploidy status and percentage of aneuploid cells) and proliferation scores. Nasal polyps of 10 patients with recurrent disease displayed higher scores for proliferation markers, and in five cases aneuploid cells with 5c exceeding rate (5cER) of 1.5-11.7% were detected. According to these results, polyps of the nasal cavity and paranasal sinuses showed low proliferation scores and were diploid. The data demonstrated that there was no increase of proliferation activity or ploidy shift toward aneuploidy in patients with allergy. Nevertheless, in recurrent disease some increase in proliferation activity and some changes in the parameters of the DNA analysis occurred, indicating more aggressive behavior of recurrent polyps in single cases.

Role for cysteinyl leukotriene receptor antagonist therapy in asthma and their potential role in allergic rhinitis based on the concept of "one linked airway disease"

OBJECTIVE

This review focuses on the shared pathophysiology of asthma and allergic rhinitis. The similarities illustrate the "one linked airway disease" concept, a unifying theory of these upper and lower airway inflammatory disorders. Since leukotrienes are mediators in both conditions, studies have been performed to assess the potential therapeutic role of cysteinyl leukotriene antagonists. The purpose of this paper is to provide an overview of the accumulating data concerning these agents in treating asthma and allergic rhinitis.

DATA SOURCES

Relevant publications obtained from a literature review.

STUDY SELECTION

Relevant publications on the topics of leukotrienes, leukotriene receptor antagonists, asthma, and allergic rhinitis were critically evaluated.

RESULTS AND CONCLUSIONS

Studies to date have documented the efficacy of cysteinyl leukotriene receptor antagonists for asthma. The pathophysiology of allergic rhinitis and its similarities to asthma suggest that these agents could play a significant therapeutic role in managing this upper airway disorder. Because the leukotriene antagonists are oral agents, they may be valuable in treating not only either condition but also both at the same time when they coexist. They appear to be beneficial when prescribed as the initial medicine and when used in conjunction with other therapies.

Modification of expression of stem cell factor by various cytokines

The local production of stem cell factor (SCF) may be an important mechanism for regulating proliferation, differentiation, and migration of various cells bearing c-kit receptors, and might be susceptible to the cytokines that serve in inflammation and tissue repair. We have demonstrated that in three murine cell lines, Balb/3T3A31, MC3T3-E1, and C3H-2K, which constitutively produced SCF with different quantity, the SCF mRNA expression was greatly enhanced in response to basic fibroblast growth factor (bFGF) or transforming growth factor beta1 (TGF-beta1). The study was carried out by in situ hybridization utilizing nonradioactive oligonucleotide probes and quantitative image analysis. Leukemia inhibitory factor (LIF) or interleukin-4 (IL-4) moderately increased SCF mRNA in all cell lines, but IL-3 did not. The dot-blot enzyme-linked immunosorbent assay (ELISA) further confirmed that SCF protein production in these cell lines and bone marrow stromal cells was markedly enhanced by TGF-beta1, although TGF-beta1 suppressed the proliferation of all these cells. bFGF also enhanced the SCF production in these cell lines, but did not in bone marrow stromal cells, suggesting a difference in their susceptibility to the cytokine. Our results suggest that TGF-beta1 and bFGF potentially modulate the biological function of cells bearing c-kit receptors through the modulation of SCF production in fibroblasts.

Allergic inflammation in upper and lower airways

OBJECTIVE

The primary reason for this review is to discuss the relationship between upper and lower airways at various levels with the emphasis on common pathophysiologic mechanisms, and how treatment of the upper airways will benefit the lower airways.

DATA SOURCES

The main source of information is derived from original articles and books, with an extensive bibliography included.

STUDY SELECTION

Studies were derived almost exclusively from articles and reviews in peer-reviewed journals.

RESULTS

The prevalence of rhinitis and asthma are both increasing. Common to both the upper and lower airways are the triggers, many of the inflammatory cells and mediators, and the treatment modalities. By contrast, there are organ-specific differences in the reaction to various stimuli in the nose or lung, with each organ manifesting its own vocabulary of response.

CONCLUSIONS

There are meaningful relationships between upper and lower airways at various levels of our understanding. Differential responses to medications help us better understand pathogenic mechanisms in rhinitis and asthma. Further, treatment of the upper airways provides additional benefit to the lower airways.

Pathophysiology of the inflammatory response

Airway allergic reactions enlist diverse cells and a multitude of chemical mediators that are responsible for the clinical symptoms of allergic rhinitis and asthma. Experiments in vitro and in animal models, as well as increasingly numerous studies in atopic human subjects, are revealing that an orchestrated continuum of cellular activities leading to airway allergic inflammation is set in motion in genetically predisposed individuals at the first exposure to a novel antigen. This sensitization step likely depends on differentiation of and cytokine release by T(H)2 lymphocytes. Among T(H)2-derived cytokines, IL-4 potently enhances B-lymphocyte generation of immunoglobulin E antibodies. The attachment of these antibodies to specific receptors on airway mast cells sets the stage for an acute inflammatory response on subsequent antigen exposure because IgE cross-linking by a bound antigen activates mast cells to release numerous inflammatory mediators. These mast cell-derived mediators collectively produce acute-phase clinical symptoms by enhancing vascular leak, bronchospasm, and activation of nociceptive neurons linked to parasympathetic reflexes. Simultaneously, some mast cell mediators up-regulate expression on endothelial cells of adhesion molecules for leukocytes (eosinophils, but also basophils and lymphocytes), which are key elements in the late-phase allergic response. Chemoattractant molecules released during the acute phase draw these leukocytes to airways during a relatively symptom-free recruitment phase, where they later release a plethora of cytokines and tissue-damaging proteases that herald a second wave of airway inflammatory trauma (late-phase response). The repetition of these processes, with the possible establishment in airway mucosa of memory T lymphocytes and eosinophils that are maintained by paracrine and autocrine cytokine stimulation, may account for airway hypersensitivity and chronic airway symptoms.

Nasal reactivity to capsaicin in patients with seasonal allergic rhinitis during and after the pollen season

BACKGROUND

We aimed to study the participation of neurogenic mechanisms in nasal allergic inflammation by assessing the effect of neurogenic stimulation on the secretory and cellular responses of nasal mucosa in patients with allergic rhinitis.

METHODS

A group of patients suffering from seasonal allergic rhinitis was challenged intranasally with incremental doses of capsaicin (0.3, 3, 12 microg) during and after the pollen season. Clinical symptoms after provocations were monitored, and unilateral nasal lavages were obtained. The nasal lavage fluid (NAL) was assayed for concentration of total protein, albumin, lactoferrin, and number of leukocytes, following by differential count.

RESULTS

Capsaicin challenge during the pollen season produced greater congestion (P < 0.01) and rhinorrhea (P < 0.05) than after the season. The intensity of burning sensation (pain) was similar on both occasions. Capsaicin failed to increase albumin content in NAL both during and after the season. Total protein was increased only after the highest dose of capsaicin (P < 0.03) after the season. The number of eosinophils in basal lavages was higher during the season. During the season, the total number of leukocytes at least doubled in 7/12 patients and the percentage of eosinophils increased in 6/12 patients after the capsaicin challenge.

CONCLUSIONS

Our study demonstrated that during the symptomatic period the nasal mucosa of allergic patients is more susceptible to neurogenic stimulation, showing enhanced secretory and inflammatory (cellular) responses.

The environmental influence on childhood asthma

The pathogenesis of allergy depends on the interaction between the time and amount of allergen exposure and the presence of nonspecific "adjuvant" factors in genetically susceptible individuals. There seems to be a period in early life during which the individual is particularly susceptible to sensitization, and there are variations in susceptibility over time. Allergens are almost ubiquitous, but the relative importance of the individual allergens varies between regions. In many temperate regions, house-dust mites used to be absent but are now more common. This may be due to modern methods of building houses. Differences in the prevalence of a particular allergy cannot explain variations in the prevalence of allergy in general. Various environmental factors that may enhance sensitization include tobacco smoke, NO2, SO2, ozone, and diesel particles. Passive smoking is by far the best established risk factor, particularly in early childhood. The indoor environment probably plays a larger role than outdoor air pollution in the development of allergic disease. The mother is not only a source of genetic information, but also an "environmental factor", as there is a close immunologic interaction between the mother and her offspring, mediated through the placenta and the breast milk, which may affect the likelihood of allergic disease. The concepts of "lifestyle" and "environment" should be expanded to include, for example, dietary changes, the microbial environment, and extensive traveling, as all the currently suspected risk factors taken together can only explain a small proportion of the geographic differences in and increasing prevalence of allergy. The future search for significant environmental factors should be interdisciplinary and be directed toward areas that have not yet been explored, thus giving "lifestyle" a broader interpretation.

Randomized placebo-controlled study comparing a leukotriene receptor antagonist and a nasal glucocorticoid in seasonal allergic rhinitis

Allergic rhinitis is an inflammatory disorder associated with local leukotriene release during periods of symptoms. Therefore, it has been suggested that antileukotrienes may be beneficial in the treatment of this disease. Leukotriene receptor antagonists have recently become available for asthma treatment, but little is known of their effects on allergic rhinitis. We have evaluated the effects of the leukotriene receptor antagonist zafirlukast versus placebo in patients with allergic rhinitis during the grass pollen season, using the nasal glucocorticoid beclomethasone dipropionate (BDP) as a positive treatment control. Thirty-three patients with seasonal allergic rhinitis were in a double-blind, double-dummy fashion randomized to treatments with oral zafirlukast (20 mg twice a day), intranasal beclomethasone dipropionate (200 microg twice a day), or placebo. The treatment was initiated 3 wk prior to the expected beginning of the grass pollen season. Patients completed a daily symptom-score list for sneezing, rhinorrhea, nasal itch, and nasal blockage during the 50-d treatment period. Nasal biopsies for quantification of local tissue eosinophilia (immunohistochemistry; EG2) were taken 1 mo before initiation of treatment and immediately after the peak of grass pollen season. Patients receiving treatment with zafirlukast had degrees of nasal symptoms similar to those in the placebo group, whereas the BDP group had significantly less symptoms compared with both treatments (p = 0.01 and p = 0.005, respectively). The numbers of activated eosinophils in the nasal tissue increased significantly during the pollen season in both the zafirlukast and the placebo groups, but not in the BDP group. These results obtained with a limited number of patients do not support any clinical efficacy of regular treatment with an oral antileukotriene in seasonal allergic rhinitis but rather favor the use of a nasal glucocorticoid.

Onset and duration of action of levocabastine nasal spray in atopic patients under nasal challenge conditions

BACKGROUND

Although prior studies have documented the rapid onset of action of topical intranasal levocabastine (LEV), little is known about its duration of action under nasal challenge conditions.

OBJECTIVES

We sought to assess the onset and duration of action of escalating doses of LEV nasal spray by using a nasal allergen challenge (NAC) model.

METHODS

Eighteen asymptomatic subjects with histories of seasonal allergic rhinitis were enrolled into a randomized, single-blind, placebo-controlled, dose-ranging crossover study. Each patient was randomly assigned to receive single doses of placebo and intranasal LEV 0.1, 0.2, and 0.4 mg during 2 parts of the study. In part 1 (onset of action), NAC consisted of a single dose of allergen administered 5 minutes after study drug treatment. In part 2 (duration of action), NAC consisted of increasing doses of allergen administered 0.5, 6, 12, and 24 hours on separate days after study drug treatment. Nasal symptom scores (NSSs) and nasal peak expiratory flow rates were measured after NAC in both phases of the study. Blood samples for plasma LEV concentrations were drawn after each NAC.

RESULTS

In part 1, NSSs were significantly lower after the administration of LEV 0.1, 0.2, and 0.4 mg compared with placebo (P <.05). In part 2, NSSs were significantly lower after LEV doses of 0.2 and 0.4 mg compared with placebo at 0.5, 6, 12, and 24 hours after treatment (P <.05). The mean provocative dose of allergen required to elicit a positive nasal reaction was increased after LEV doses of 0.2 and 0.4 mg at 0.5, 6, and 12 hours after treatment. Nasal peak expiratory flow rates demonstrated no significant differences between LEV and placebo for any doses at any time points. Mean plasma LEV concentrations were low (range, 0 to 3. 7 ng/mL) after all doses and did not correlate with drug efficacy.

CONCLUSIONS

Single intranasal LEV doses of 0.1, 0.2, and 0.4 mg significantly reduced the severity of the immediate nasal response to allergen when administered 5 minutes before NAC. This protective effect against NAC continued to be present 24 hours after administration of LEV doses of 0.2 and 0.4 mg. Efficacy in blocking the reaction to NAC did not correlate with plasma LEV levels, suggesting that the inhibitory effect was due largely to topical rather than systemic effects.

Diagnosis and management of rhinitis

This article reviews the differential diagnoses for rhinitis, medications available for the treatment of rhinitis, and special circumstances (such as pregnancy or medication side-effects) that may influence a clinician's decision. Considering the economic impact of rhinitis, the cost of prescription medications, and quality-of-life issues that are affected by rhinitis, physicians dealing with managed care organizations should make their diagnosis and treatment decisions carefully.

Subjective and objective assessments in patients with seasonal allergic rhinitis: effects of therapy with mometasone furoate nasal spray

BACKGROUND

Efficacy of topical nasal steroid therapy for allergic rhinitis is usually evaluated by patient and clinician assessments of subjective symptom changes in diaries and at clinical interviews.

OBJECTIVE

We sought to complement the subjective measures with objective measures of nasal cytology, biochemistry, and function.

METHODS

In this double-blind, randomized study patients with seasonal allergic rhinitis (SAR) 12 years of age or older received 200 microg mometasone furoate nasal spray (n = 80) or placebo spray (n = 41) once daily for 2 weeks. Subjective assessments by clinician and patient comprised symptom/sign scores and overall therapeutic response evaluations. Objective measures included nasal cytology, nasal biochemistry, nasal airway resistance (NAR), mucociliary clearance, and olfactory functions.

RESULTS

Mometasone furoate produced a significantly greater decrease than placebo in subjective measures of SAR for total symptom score (-46% vs -30%, p < 0.05), total nasal score (-47% vs -30%, p < 0.024), individual nasal symptom scores, and overall therapeutic response. The objective measures of eosinophil, basophil, and neutrophil counts and mucociliary clearance were significantly better in mometasone furoate- than in placebo-treated patients. Similarly, within-treatment statistically significant improvements were produced by mometasone furoate but not by placebo sprays for levels of eosinophilic cationic protein, tryptase and albumin, NAR, and odor identification. Significant positive correlations were found between NAR and nasal stuffiness and between eosinophils, basophils, and neutrophils and both eosinophilic cationic protein and albumin.

CONCLUSION

Subjective measures of SAR were significantly improved in the mometasone furoate group by comparison with placebo-treated patients. Objective assessments supported the subjective findings because within-treatment measures were frequently significantly improved after mometasone furoate treatment but not after placebo treatment.

A murine model of allergic rhinitis: studies on the role of IgE in pathogenesis and analysis of the eosinophil influx elicited by allergen and eotaxin

BACKGROUND

Allergic rhinitis is a prevalent disease with significant morbidity. Studies of its pathophysiology in human subjects have been limited. Nasal biopsy specimens are difficult to obtain, and nasal secretions incompletely reflect the cellular and molecular events in the mucosa. IgE-mediated mast cell activation and the elaboration of factors promoting eosinophil development and chemotaxis are likely to participate in pathogenesis.

OBJECTIVES

We sought to develop a murine model of allergic rhinitis, to use it to assess the role of IgE in pathogenesis, and to study the effects of IL-5 and eotaxin in the nasal mucosa.

METHODS

A protein extract of Aspergillus fumigatus (Af) was instilled intranasally in mice. Histologic changes were examined in wild-type and IgE-deficient (IgE-/-) animals. The effect of eotaxin administration was assessed in wild-type and IL-5 transgenic mice.

RESULTS

Af-treated mice developed a nasal mucosal eosinophil influx comparable to that described for humans. This histology was distinct from that observed in a murine model of Af-induced asthma. The pathology appeared over a time course similar to that reported for human subjects. There was no difference in the intensity of the mucosal inflammatory infiltrate of Af-treated IgE-/- mice compared with wild-type mice. Eotaxin was able to recruit eosinophils to the mucosa but only in IL-5 transgenic animals.

CONCLUSION

We describe a murine model for allergic rhinitis with an eosinophilic infiltrate comparable to that found in human disease and have demonstrated that rhinitis can arise in the absence of IgE. We have shown that the eosinophil influx can be induced by eotaxin in the presence of IL-5.

Indoor allergen levels and other environmental risk factors for sensitization in Estonian homes

The prevalence of allergic disease is low in Eastern Europe for reasons that are poorly understood. Our study aimed to investigate the levels of exposure to indoor allergens and living conditions among Estonian infants in relation to sensitization. Dust samples were collected during four winter months in 1993/94 from the homes of 197 infants participating in a prospective study of sensitization. Information about living conditions was collected through a home visit and interviewing the mothers when the children were 6 weeks old. Three dust samples were collected from each home; i.e., from the infant's mattress, bedroom floor, and living-room carpet. The levels of allergens were determined by ELISA with monoclonal antibodies. The highest allergen level in a home was regarded as the peak value. The peak geometric mean values (+/-SD) of Der p 1 and Der f 1 were 0.3 (0.07-1.4) microg/g dust, of Can f 1, 0.86 (0.23-3.12) microg/g dust, and of Fel d 1, 0.1 (0.01-0.9) microg/g dust. In 12 homes (9%), the peak value of house-dust mite (HDM) allergens exceeded 2 microg/g dust, with Der p 1 as the dominating allergen. Multivariate analyses indicated that high levels of HDM allergens were more common in apartments that were on the ground floor or first floor, that were heated with stoves, and/or that had a dampness problem. The mean allergen levels at home were similar in children sensitized to HDM (n=17, 0.29 vs 0.3 microg/ g dust), dog (n=5, 0.55 vs 1.06 microg/g dust, and cat (n=18, 0.21 vs 0.09 microg/g dust) and in children who were not sensitized to these allergens. Most of the sensitized children were exposed to relatively low allergen levels at home; i.e., below 1 microg/g dust. This level was exceeded in the homes of 4/17 mite-, 5/18 cat-, and 0/5 dog-sensitized children. The similar levels of the major indoor allergens in Estonia and in Scandinavia indicate that the large differences in atopy prevalence among children and young adults in the two regions are not due to differences in allergen exposure. No allergen threshold level for sensitization was identified.

Peripheral H1-blockade effect of fexofenadine

BACKGROUND

Studies of the suppressive effect of H1-receptor antagonists on the histamine-induced wheal and flare are useful for assessing peripheral H1-blockade.

OBJECTIVE

To compare the peripheral H1-blockade produced by fexofenadine, 60 mg twice daily or 120 mg once daily; loratadine, 10 mg once daily; and placebo during 24 hours.

METHODS

In this randomized, double-blind, single-dose, crossover study in 20 subjects, the wheals and flares produced by epicutaneous tests with histamine phosphate 1 mg/mL were measured before and at intervals (20, 40, 60 minutes, hourly until 12 hours, and 24 hours) after the ingestion of fexofenadine, 60 mg twice daily; fexofenadine, 120 mg once daily; loratadine, 10 mg once daily; or placebo.

RESULTS

All active medications effectively suppressed the histamine-induced wheal and flare for 24 hours compared with placebo. Fexofenadine 60 mg twice daily and fexofenadine 120 mg once daily had a faster onset of action than loratadine in this experimental model.

CONCLUSIONS

Peripheral H1-blockade studies are useful for investigation of the differences among H1-receptor antagonists. They complement large clinical trials in which efficacy is subjectively assessed using symptom scores, and which are more likely to demonstrate similarities among the different medications in this class, and among different doses of the same H1-receptor antagonist.