Intranasal histamine challenge in normality and allergic rhinitis

Superoxide dismutase failed to attenuate allergen-induced nasal congestion in ragweed-sensitized dogs

We hypothesized that augmentation of antioxidant defenses with exogenous superoxide dismutase (SOD), an enzyme that provides an initial defense against oxidative injury, would attenuate allergen-induced nasal congestion in the canine model of allergic rhinitis. Nasal congestion was evaluated by the measurements of nasal resistance and the volume of the nasal passage. In five nonsensitized dogs, 30,000 U of SOD from bovine erythrocytes delivered by aerosol to the nasal passages before histamine challenge reduced the histamine-induced nasal congestion. At 30 min postchallenge, nasal resistance was 1.14 +/- 0.2 cmH2O.l(-1).min(-1) in the saline pretreatment study vs. 0.36 +/- 0.02 cmH2O.l(-1).min(-1) in the SOD pretreatment study (P < 0.05), and volume of nasal passage was 10.9 +/- 0.5 cm3 vs. 17.4 +/- 1.3 cm3 (P < 0.05), respectively. In five sensitized dogs, however, neither an analogous pretreatment with SOD nor intranasal aerosolized pretreatment with 30,000 U of SOD conjugated to polyethylene glycol attenuated ragweed-induced nasal congestion. Also, systemic application of SOD did not attenuate responses to challenges with histamine and ragweed in nonsensitized and sensitized dogs, respectively. The antioxidant-induced attenuation of nasal congestion in nonsensitized dogs confirms validity of the model and indicates the involvement of free radical-mediated damage in the genesis of the histamine-induced congestion. In sensitized dogs, the data do not support the hypothesis that oxidative stress is a clinically significant component of acute ragweed-induced nasal congestion. The data do not support the use of SOD for acute protection against allergic rhinitis.

Immunohistochemical localization of histamine receptor subtypes in human inferior turbinates

Histamine is an important chemical mediator in allergic rhinitis and plays an important role in eliciting the nasal symptoms of the disorder. However, the immunohistochemical localization of histamine receptor subtypes (H1R, H2R, H3R, and H4R) in human nasal mucosa is unknown. There are also no prior studies of H3R and H4R in human nasal mucosa. The objective of this study was to examine the distribution of histamine receptor subtypes in the human inferior turbinates by an immunohistochemical method. H1R was localized primarily in the epithelium, vessels, and nerves. H2R was localized primarily in the epithelium and the glands. H3R and H4R were clearly distributed on the nerves. In addition, H1R, H3R, and H4R were clearly localized on the same nerves. This result indicates that H1R, H3R, and H4R adjoin and regulate each other in the same nerves. All histamine receptor subtypes may play some role in patients with allergic rhinitis.

Nasal mucosal histamine reactivity among young students and teachers, having no or prolonged exposure to a deteriorated indoor climate

BACKGROUND

In a study performed in the spring of 1995, we found a significantly greater nasal mucosal histamine reactivity among teachers, who had worked for several years in a recently renovated moisture-damaged school, than in those in a control school. In the present study we investigated the students who begun their high-school studies at both schools in the autumn of 1995 and compared them with the teachers as regards mucosal reactivity, atopy and symptoms.

METHODS

Twenty-eight teachers in the target school, 18 teachers in the control school and 45 students from each school underwent a nasal histamine provocation test and a skin-prick test. They also answered a standardized questionnaire.

RESULTS

The teachers in both schools had more marked nasal mucosal histamine reactivity at the lowest provocation concentrations than the students. The histamine provocation curve of the target school teachers had consistently higher values than that of the students (P = 0.0001), but its slope and shape were similar (P = 0.15), while the slope of the provocation curve of the control school teachers was flatter. However, there was only a borderline significance in this respect compared to the students (P = 0.07). Teachers with a dry and crusty appearance of the nasal mucosa on anterior rhinoscopy reacted more strongly to histamine provocation than those without this finding (P = 0.0004). There was a significantly higher frequency of skin-prick test positivity (SPT+) among the students (P = 0.03). There were no significant differences in nasal mucosal histamine reactivity between atopic and non-atopic subjects out of pollen season.

CONCLUSIONS

Teachers had a significantly greater mucosal histamine reactivity than the students, whereas the latter had a significantly higher frequency of atopy. These results are compatible with an age-related pattern of mucosal reactivity. A crusty appearance of the nasal mucosa seems to predispose to an increase in histamine reactivity. There were no significant differences according to histamine reactivity between atopic and non-atopic subjects.

Diagnosis and management of rhinitis: complete guidelines of the Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology. American Academy of Allergy, Asthma, and Immunology

This document contains complete guidelines for diagnosis and management of rhinitis developed by the Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology, representing the American Academy of Allergy, Asthma and Immunology, the American College of Allergy, Asthma and Immunology and the Joint Council on Allergy, Asthma and Immunology. The guidelines are comprehensive and begin with statements on clinical characteristics and diagnosis of different forms of rhinitis (allergic, non-allergic, occupational rhinitis, hormonal rhinitis [pregnancy and hypothyroidism], drug-induced rhinitis, rhinitis from food ingestion), and other conditions that may be confused with rhinitis. Recommendations on patient evaluation discuss appropriate use of history, physical examination, and diagnostic testing, as well as unproven or inappropriate techniques that should not be used. Parameters on management include use of environmental control measures, pharmacologic therapy including recently introduced therapies and allergen immunotherapy. Because of the risks to patients and society from sedation and performance impairment caused by first generation antihistamines, second generation antihistamines that reduce or eliminate these side effects should usually be considered before first generation antihistamines for the treatment of allergic rhinitis. The document emphasizes the importance of rhinitis management for comorbid conditions (asthma, sinusitis, otitis media). Guidelines are also presented on special considerations in patients subsets (children, the elderly, pregnancy, athletes and patients with rhinitis medicamentosa); and when consultation with an allergist-immunologist should be considered.

Histamine-induced internalization of substance P receptors in myoepithelial cells of the guinea pig nasal glands

Numerous substance P (SP) immunoreactive nerve fibers were located around submucosal glands in the guinea pig nasal mucosa. Since these SP positive nerve fibers were also positive for vasoactive intestinal polypeptide, and to a lessor extent for neuropeptide Y, they were presumed to be parasympathetic fibers. SP receptor positive structures were observed exclusively on the membrane of myoepithelial cells in normal nasal mucosa, suggesting that myoepithelial cells are targets of SP positive fibers. SP receptor-like immunoreactivity was observed associated with intracellular organella of myoepithelial cells 5 min after intranasal histamine challenge, which may indicate the molecular basis for histamine-induced nasal discharge.