The nasal allergic reaction: observations on the role of histamine

Antihistamines and itch

Histamine is one of the best-characterized pruritogens in humans. It is known to play a role in pruritus associated with urticaria as well as ocular and nasal allergic reactions. Histamine mediates its effect via four receptors. Antihistamines that block the activation of the histamine H₁receptor, H₁R, have been shown to be effective therapeutics for the treatment of pruritus associated with urticaria, allergic rhinitis, and allergic conjunctivitis. However, their efficacy in other pruritic diseases such as atopic dermatitis and psoriasis is limited. The other histamine receptors may also play a role in pruritus, with the exception of the histamine H₂receptor, H₂R. Preclinical evidence indicates that local antagonism of the histamine H₃receptor, H₃R, can induce scratching perhaps via blocking inhibitory neuronal signals. The histamine H₄receptor, H₄R, has received a significant amount of attention as to its role in mediating pruritic signals. Indeed, it has now been shown that a selective H₄R antagonist can inhibit histamine-induced itch in humans. This clinical result, in conjunction with efficacy in various preclinical pruritus models, points to the therapeutic potential of H₄R antagonists for the treatment of pruritus not controlled by antihistamines that target the H₁R.

Nasal allergic response mediated by histamine H3 receptors in murine allergic rhinitis

BACKGROUND

Histamine is one of the most important chemical mediators causing nasal allergic symptoms, and H1 receptor antagonist have been used as the treatment first choice in nasal allergy. The presence of H3 receptors has also been determined in the human nasal mucosa, but few studies have investigated the involvement of H3 receptors in nasal allergy.

OBJECTIVE

We used a murine allergic model to investigate the presence of nasal mucosa H3 receptor mRNA and any H3 receptor agonist or antagonist influences on clinical nasal allergic symptoms.

METHODS

H3 receptor mRNA in nasal mucosa was investigated by reverse-transcription polymerase chain reaction. OVA-sensitized mice were given an intraperitoneal injection of H3 receptor agonist or antagonist, and clinical nasal allergic symptoms were scored over 10 minutes after nasal provocation of OVA. Inhibition of nasal allergic symptoms was also examined using an H1 receptor antagonist alone and using a both an H3 receptor agonist and an H1 receptor antagonist.

RESULTS

H3 receptor mRNA was identified in the murine nasal mucosa. The H3 receptor agonist (R)-alpha-metylhistamine significantly inhibited clinical nasal allergic symptoms of OVA-sensitized mice. The H3 receptor agonist and H1 receptor antagonist inhibited clinical nasal allergic symptoms in the murine allergic model more strongly than the single drug.

CONCLUSION

The foregoing results indicate that H3 receptors are involved in modulation of nasal allergy. H3 receptor agonists can also be useful as a novel therapeutic approach in nasal allergy. Both H3 receptor agonist and H1 receptor antagonist may be more effective than a single drug.

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.

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.

Effect of H1 and H2 antagonists on nasal symptoms and mediator release in atopic patients after nasal allergen challenge during the pollen season

During the pollen season, quantitative determination of the chemical mediators and eosinophil count was performed in 16 patients with hay fever after nasal allergen challenge (NAC). The aim of this study was objectively to assess the effect of H1 and of a combination of H1 and H2 antagonists on nasal symptoms, mediator release, and eosinophil count during an allergic reaction. NAC was performed at baseline (V1), 2 weeks after treatment with cetirizine 10 mg/day (V2), and after a combined therapy with cetirizine 10 mg and cimetidine 800 mg a day during the following week (V3). Results showed a significant (p < 0.05 or p < 0.01) relief of nasal symptoms such as: itching, sneezing, rhinorrhea and congestion, and of objective parameter such as: reduction of the number of sneezes after NAC at V2 and V3. Neither H1 antagonist nor a combination of H1 and H2 antagonists showed any effect on eosinophilia and ECP concentration caused by natural allergen exposure, nor on histamine and tryptase release immediately after NAC. When a combination of H1 and H2 antagonists was administered significant reduction of the nasal airway resistance and increase of the nasal air flow were demonstrated.

Reduction by NG-nitro-L-arginine methyl ester (L-NAME) of antigen-induced nasal airway plasma extravasation in human subjects in vivo

In non-allergic subjects, histamine induced a reduction of minimal nasal cross-sectional area (Amin) and an increase in albumin release into nasal lavage. The effect of histamine on albumin release was inhibited by pretreatment with NG-nitro-L-arginine methyl ester (L-NAME), 1 mumol but not by D-NAME, 1 mumol. L-NAME, 1 and 10 mumol, did not inhibit the histamine-induced reduction of Amin. In subjects allergic to grass pollen, antigen challenge induced a reduction in Amin that was not changed by pretreatment with L-NAME, and an increase in albumin release that was inhibited by L-NAME, 1 mumol. The data support a role for nitric oxide in mediating plasma extravasation in the nose induced by antigen challenge or histamine.

The effect of topical fluticasone propionate on intranasal histamine challenge in subjects with perennial allergic rhinitis

The mechanism of action of topical intranasal steroids is obscure. To investigate this, we have studied the effects of a topical intranasal corticosteroid, fluticasone propionate on nasal airflow resistance (Rnaw), secretions, cytological smears and symptoms. Fluticasone propionate aqueous nasal spray was given to 11 patients with perennial allergic rhinitis in a double-blind, placebo-controlled study. On each day, patients were challenged with ascending doses of histamine. Rnaw, secretion volume, total protein, mucin, lysozyme and albumin were measured. Nasal smears were taken and sneezes counted. Diary card data were collected for both treatment periods. There was a significant, dose-related increase in Rnaw and sneezing on histamine challenge. A single dose of fluticasone had no effect on any parameter. After 4 weeks of treatment, resistance measurements were reduced (post-challenge g.m.2.8 cmH2O/l/s, Q1-Q3 1.6-4.8; placebo 4.2, 2.9-5.3: P < 0.0001) as were baseline secretion volumes (mean 2.4 ml/5 min, c.i.1.9-3.0; placebo 3.3, 2.8-3.8: P < 0.05). Eosinophil counts were suppressed (fluticasone 5.8%, c.i. 4.0-15.7; placebo 23.3%, 12.4-34.1: P < 0.05) and the composite symptom score reduced (P < 0.05). Fluticasone has long-term effects on the nasal response to histamine in perennial allergic rhinitis and part of this effect is likely to be vascular.

Intranasal histamine challenge in normality and allergic rhinitis

A series of investigations was performed in which histamine challenge was used to compare nasal responsiveness in 20 normal subjects and 20 with allergic rhinitis. There was found to be a lower threshold of reactivity (D100) to histamine in allergic subjects as measured by resistance changes (geometric mean, 0.53 mg/ml; normal subjects, 2.15: p = 0.022). This may represent increased number or sensitivity of histamine receptors on the nasal capacitance vessels. The loss of a laser Doppler response to a supramaximal histamine stimulus (normal subjects, 102% increase in flux at 3 minutes; p < 0.05) was observed in patients with allergic rhinitis and indicates either a down-regulation of the capillary system or an altered effect of histamine on superficial vessels, perhaps mediated by a shift in histamine receptor type. There was an observed increase in neutrophils at the mucosal surface under baseline conditions (rhinitis median, 49.6%; normal subjects, 32.72%: p < 0.05), which suggests an important primary role in the pathogenesis of this condition for this active cell. The observed increase in secretory volume response to histamine in allergic subjects, which persisted beyond 40 minutes after a single D100 challenge, may be related to an altered sensitivity of glandular tissue. There are important changes in nasal reactivity to histamine challenge in allergic rhinitis that may have implications for its pathogenesis.

Early and late nasal symptom response to allergen challenge. The effect of pretreatment with a glucocorticosteroid spray

We challenged 30 pollen-sensitive volunteers with allergen, recorded symptoms and signs over a 10-h period, and rechallenged them after 24 h, in order to characterize the early and late allergic symptom response in the nose. The challenge was performed after topical pretreatment with the glucocorticosteroid budesonide (200 micrograms twice daily) for 14 d and with placebo in a double-blind, cross-over trial. The early response, consisting of sneezing, discharge, and blockage, was followed by a weak late response, consisting of a few sneezes and nose-blowings, and of a sustained nasal blockage. These symptoms did not have a well-defined peak in time, and a biphasic symptom curve could not be identified. The rechallenge response showed increased nasal responsiveness. The degree of budesonide effect on the early response varied, depending on the symptom; there was a marked effect on sneezing (72% reduction; P < 0.01), a moderate effect on discharge (37% reduction; P < 0.01), and a slight effect on blockage (17% reduction of nasal inspiratory peak flow rate; P < 0.02). The degree of inhibition of the rechallenge response was similar to the effect on the initial early response. The effect on the late response was very pronounced for all symptoms and signs (97% reduction of sneezes, 76% reduction of nose-blowings, 96% reduction of blockage; P < 0.01). In conclusion, we found it difficult in the individual subject to identify a well-defined late symptom response by criteria similar to those employed to characterize the late response in the bronchi. The effect of budesonide was more marked on sneezing than on blockage, and the drug was considerably more effective on the late response than on the early response.