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Notes: Background: The inhibitory effect of antihistamines on allergen-induced skin reactions can impair the results of allergen skin testing, which are necessary for the diagnosis of atopic diseases. This study was designed to determine the time period required for the inhibitory effect of ebastine on allergen-induced skin reactivity to disappear completely. Methods: This was a double-blind, placebo-controlled, parallel-group study including 23 out of 27 randomized patients. They received either ebastine 20 mg or placebo once daily for 7 days. At the end of treatment, allergen challenge was performed daily for 7 days. Histamine challenge was performed on day 1 (6 and 24 h) and day 5 after treatment. The wheal and flare surface areas were measured and analyzed. Results: Highly significant inhibition of the wheal and flare response induced by allergen was observed after ebastine treatment on days 1 and 2 as compared with placebo (P〈0.01 for both). The inhibition was reduced, although still significant, by day 3 (P〈0.05). No significant difference was observed by day 4 between the ebastine and the placebo groups. The effects of histamine challenge were significantly reduced in the ebastine compared with the placebo group at day 1 (6 and 24 h), and were similar at day 5 after treatment. Conclusions: Our results show that the wheal and flare response to allergen after ebastine discontinuation returns to placebo values after 4 days. Therefore, patients using ebastine need to be antihistamine-free for 4 days before the skin prick test. This is valuable information for the allergologist seeking to diagnose allergen sensitivity.

Notes: The effects of nasal administration of increasing doses of exogenous substance P have been studied in patients with allergic rhinitis treated with placebo or with the H1 antagonist certirizine (10 mg twice daily for 3 days). Responses to substance P were assessed by posterior rhinomanometry (measuring nasal airway resistance) and by measure of histamine. protein and albumin production and cell recovery in nasal lavage fluids before and after challenge. Substance P induced a dose-dependent increase in nasal airway resistance which was similar after treatment with either cetirizine or placebo (maximal increase in nasal airway resistance was 4-2-fold greater than the baseline with the placebo and 4-7-fold greater than the baseline with cetirizine). No histamine release was observed. Similar increases in protein and albumin production were observed after stimulation with substance P along with the placebo (protein: from 0.35±0.11 to 3.31±0.62 mg and albumin: from 0.09±0.04 to 2.08±0.39 mg) and when combined with cetirizine treatment (proteins: from 0.42±0.09 to 3.62±0.77 and albumin: from 0.17±0.04 to 2.19±0.51 mg). After stimulation with substance P, percentages of neutrophils recovered in nasal fluids increased from 26.2±11.5 to 54.5±9.5 with the placebo and from 35.5±11.0 to 53.6±9.5 with cetirizine. Eosinophils were inconsistently found after substance P stimulation during both treatments. In conclusion, nasal response lo substance P is not modified by cetirizine which suggests that the effect of substance P is not secondary to histamine release in the nose in man.

Notes: Endotoxins found in occupational settings constitute a risk factor in the severity of respiratory allergic symptoms.Objectives To assess the airborne concentrations of major rat allergen (Rat n 1) and endotoxin under various circumstances.Methods We took 483 airborne samples from 12 sites: 114 individual samples for endotoxin measurements and 113 for Rat n 1, from 38 workers (nine animal technicians, nine laboratory technicians, nine scientists and 11 students); and 256 static samples in rat rooms and experimental rooms, with or without disturbance, for simultaneous endotoxin and Rat n 1 measurements. Rat n 1 was measured with a two-site monoclonal ELISA and endotoxins with the Limulus method.Results Airborne Rat n 1 and endotoxin were significantly higher in rat rooms than in experimental rooms. Animal technicians had the greatest exposure to both Rat n 1 and endotoxin. Cage cleaning and rat feeding induced the highest exposure to Rat n 1 and endotoxin. Furthermore, we observed no significant difference in endotoxin exposure between researchers with or without rat contact during the sample period. There was no correlation between the number of rats present and airborne endotoxin concentrations.Conclusions Exposure to airborne Rat n 1 and endotoxin is higher during cleaning and feeding tasks than during any other task, we feel that a major source of both is contaminated bedding that becomes airborne during disturbance.

Notes: Background Levels of endotoxins greatly differ according to environmental settings.Objective To study the effect of lipopolysaccharide (LPS) at increasing doses (0.1–1000 ng) on allergen sensitization and challenge in the mouse.Methods Mice were sensitized systemically and challenged locally with ovalbumin (OVA) in the presence or absence of LPS. Inflammation was assessed by determining total and differential cell counts and T-helper type 2 (Th)2 cytokine (IL-4 and IL-5) levels in bronchoalveolar lavage fluid (BALF). Total and OVA-specific IgE levels were quantified in serum. Airway hyper-responsiveness (AHR) was assessed by whole-body barometric plethysmography.Results Administered prior to sensitization, LPS at 100 or 1000 ng dose-dependently decreased allergen- induced total and OVA-specific IgE, airway eosinophilia and Th2 cytokines in BALF, without changing AHR. Administered during OVA challenge, LPS at 1 ng (an infra-clinical dose) or 100 ng (a dose triggering neutrophilia) enhanced airway eosinophilia, without affecting IgE levels or AHR.Conclusion Our data clearly demonstrate that exposure to LPS influences allergen-induced IgE production and airway eosinophilia in a time and dose-dependent manner, preventing IgE production and development of eosinophilia when administered during allergen sensitization at high doses, and inducing exacerbation of eosinophilia when administered upon allergen challenge at low doses, including infra-clinical doses.

Notes: Background The traditional neurotransmitter catecholamine and the neuropeptide tyrosine in sympathetic airway nerves have been proposed to be involved in the pathogenesis of airway diseases.Objective The aim of the present study was to investigate the effect of allergic airway inflammation on the expression of catecholamine enzyme tyrosine hydroxylase (TH), neuropeptide tyrosine (NPY) and tachykinins in mouse sympathetic airway ganglia.Methods Using neuronal tracing in combination with immunohistochemistry, the present study was designed to characterize TH, NPY and tachykinin profiles of superior cervical (SCG) and stellate ganglia after allergen challenge.Results The vast majority of fast blue-labelled SCG neurons (allergen: 97.5±1.22% (mean±SEM) vs. controls: 94.5±1.48%, P=0.18) and stellate neurons (allergen: 95.3±1.01% vs. controls: 93.6±1.33%, P=0.34) were immunoreactive for TH. Of the TH immunoreactive and fast blue-labelled SCG neurons, 52.0±1.01% allergen vs. 51.2±3.58% controls (P=0.83) and stellate neurons, 57.3%±0.97 allergen vs. 56.4±1.65% controls (P=0.64) were positive for TH only but not NPY, whereas 45.3±1.05% allergen vs. 43.3±1.18% controls (P=0.47) of fast blue-labelled SCG neurons and 37.9±0.86% allergen vs. 37.1±1.24% controls (P=0.62) of fast blue-labelled stellate neurons were immunoreactive for both TH and NPY immunoreactivities. There was a trend of an increase, but not significant one, in the percentage of TH-/NPY-immunoreactive and fast blue-labelled neurons in allergen-treated animals in comparison with the controls. Tachykinins, however, were not expressed by sympathetic neurons and were also not induced in sympathetic neurons after allergen challenge.Conclusion The present study indicates that allergic airway inflammation does not alter the expression of noradrenalin and NPY in sympathetic ganglia and also shows that sympathetic neurons do not respond to allergic airway inflammation with tachykinins induction. However, a participation of catecholamine and NPY in the pathogenesis of allergic airway inflammation cannot be excluded in the present study as a higher neurotransmitter output per neuron following allergen challenge could be possible.

Notes: Background Repeated inhalation of allergen at low-dose induces an increase in bronchial hyper-responsiveness, without any associated symptom. The concomitant events in the bronchus have not been described.Objective We have studied the dynamic number of mast cells in the airways of patients with mild asthma before and after repeated inhalation of allergen at low-dose and the expression of nerve growth factor (NGF), which is reported to promote growth and survival of mast cells.Methods Twelve patients with mild asthma to cat allergen were enrolled at random in a blind placebo-controlled study, and submitted to repeated low-dose allergen exposure (1/5 of the provocative dose). Mast cells were immunolocalized using an antibody against mast cell tryptase. NGF and its high affinity receptor, TrkA, were immunolocalized using anti-NGF and anti-TrkA antibodies, respectively. NGF mRNA was quantified by competitive polymerase chain reaction (PCR) after reverse transcription of total RNA extracted from bronchial biopsy. NGF protein levels were measured by ELISA in bronchoalveolar lavage (BAL) fluid.Results Bronchial mast cell number was increased significantly after allergen exposure as compared with before. NGF expression in the bronchus was immunolocalized mainly to epithelial cells, but also to fibroblasts, blood vessels, and a few infiltrated cells. NGF mRNA levels in bronchial biopsies were increased significantly after allergen exposure. The high affinity receptor for NGF, TrkA, was immunolocalized to the infiltrated mast cell membrane.Conclusion Our study shows that the increase in the number of mast cells and in the expression of NGF induced by allergen exposure in the bronchus of asthmatic patients is occurring before the onset of symptoms. In addition, our finding of the presence of the TrkA receptor on the membrane of the infiltrated mast cell in situ brings evidence of the mast cell as a target cell for the growth factor activity of NGF in the airways in asthma.

Notes: We have investigated the nasal response to substance P after pollen exposure in seasonal allergic rhinitic patients. Seven patients with strictly seasonal allergic rhinitis were studied during the pollen season, 24 h after nasal challenge with pollen. They received increasing doses of nebulized substance P (0 to 80 nmol) in each nostril. Responses were assessed by measurement of nasal airway resistance by posterior rhinomanometry and quantification of albumin, histamine, and inflammatory cells in the nasal lavage fluid. Nasal airway resistance increased in a dose-dependent manner after substance P challenge. Protein and albumin in nasal lavage fluids increased after administration of substance P: from 2.6 ± 0.3 to 6.8 ± 1.1 mg for protein (P≤0.01) and from 0.2 ± 0.1 to 3.1 ± 0.6 mg for albumin (P≤0.02). Expressed as a percentage of total protein, albumin increased from 10.5 ± 3.6% to 39.9 ± 3.5% (P≤0.02), suggesting occurrence of plasma leakage. No histamine release was observed after challenge with substance P. Total cell counts significantly increased from 11.4 ± 2.4 to 41.8 ± 17.3 × 103 cells/ml after substance P (P≤0.05). Eosinophils were already numerous before substance P challenge (2.1 ± 0.7 × 103 cells/ml), and the number of eosinophils markedly increased in all patients after substance P (for the whole group, 25.8 ± 13.3 cells/ml, P≤0.05). In contrast, the number of neutrophils only slightly increased in five patients, and changes did not reach significance for the group as a whole. Our results show that substance P induces nasal obstruction and albumin extrusion in allergic rhinitic patients after repeated pollen exposure. These vascular phenomena are associated with recruitment of eosinophils. Since substance P is known to be released after nasal allergen challenge, our data suggest a role for substance P in the chronic eosinophilic inflammation of the nasal mucosa observed in symptomatic allergic rhinitis.

Notes: Neurogenic inflammation encompasses the release of neuropeptides from airway nerves leading to inflammatory effects. This neurogenic inflammatory response of the airways can be initiated by exogenous irritants such as cigarette smoke or gases and is characterized by a bi-directional linkage between airway nerves and airway inflammation. The event of neurogenic inflammation may participate in the development and progression of chronic inflammatory airway diseases such as allergic asthma or chronic obstructive pulmonary disease (COPD). The molecular mechanisms underlying neurogenic inflammation are orchestrated by a large number of neuropeptides including tachykinins such as substance P and neurokinin A, or calcitonin gene-related peptide. Also, other biologically active peptides such as neuropeptide tyrosine, vasoactive intestinal polypeptide or endogenous opioids may modulate the inflammatory response and recently, novel tachykinins such as virokinin and hemokinins were identified. Whereas the different aspects of neurogenic inflammation have been studied in detail in laboratory animal models, only little is known about the role of airway neurogenic inflammation in human diseases. However, different functional properties of airway nerves may be used as targets for future therapeutic strategies and recent clinical data indicates that novel dual receptor antagonists may be relevant new drugs for bronchial asthma or COPD.

Notes: Several studies have compared the cutaneous efficacy of cetirizine and loratadine and their onset of action. We assessed the nasal effect of these two antihistamines in a randomized, double-blind, crossover, placebo-controlled trial in order to compare objectively their efficacy and onset of action in the noses of patients with allergic rhinitis. Nasal challenge was performed by nebulization of increasing doubling doses of histamine (0, 0.04-1.28 mg/nostril) in 12 patients (eight men, four women, aged 22-39 years). Nasal airway resistance (NAR) was measured by posterior rhinomanometry either 1.5 h or 4 h after intake of cetirizine (10 mg), loratadine (10 mg), or placebo. Baseline NAR was identical between all study days (2.60-2.88 cmH2O·1−1·s). One and a half hours after intake, the increase in NAR induced by histamine was significantly reduced by both cetirizine and loratadine in contrast to placebo. However, with cetirizine the nasal obstruction was significantly lower than with loratadine (P〈0.05). Four hours after intake, a similar inhibition of the nasal obstruction caused by histamine was observed with both cetirizine and loratadine (P〈0.05). In conclusion, this study found cetirizine and loratadine to have similar nasal efficacy at therapeutic dosage 4 h after intake, whereas cetirizine was more effective than loratadine 1.5 h after intake. In agreement with the results observed in the skin, our study suggests a more rapid onset of action of cetirizine in the nose in allergic rhinitis.