Terfenadine exerts antiallergic activity reducing ICAM-1 expression on nasal epithelial cells in patients with pollen allergy

Development and analysis of a comprehensive diagnostic model for aortic valve calcification using machine learning methods and artificial neural networks

BACKGROUND

Although advanced surgical and interventional treatments are available for advanced aortic valve calcification (AVC) with severe clinical symptoms, early diagnosis, and intervention is critical in order to reduce calcification progression and improve patient prognosis. The aim of this study was to develop therapeutic targets for improving outcomes for patients with AVC.

MATERIALS AND METHODS

We used the public expression profiles of individuals with AVC (GSE12644 and GSE51472) to identify potential diagnostic markers. First, the R software was used to identify differentially expressed genes (DEGs) and perform functional enrichment analysis. Next, we combined bioinformatics techniques with machine learning methodologies such as random forest algorithms and support vector machines to screen for and identify diagnostic markers of AVC. Subsequently, artificial neural networks were employed to filter and model the diagnostic characteristics for AVC incidence. The diagnostic values were determined using the receiver operating characteristic (ROC) curves. Furthermore, CIBERSORT immune infiltration analysis was used to determine the expression of different immune cells in the AVC. Finally, the CMap database was used to predict candidate small compounds as prospective AVC therapeutics.

RESULTS

A total of 78 strong DEGs were identified. The leukocyte migration and pid integrin 1 pathways were highly enriched for AVC-specific DEGs. CXCL16, GPM6A, BEX2, S100A9, and SCARA5 genes were all regarded diagnostic markers for AVC. The model was effectively constructed using a molecular diagnostic score system with significant diagnostic value (AUC = 0.987) and verified using the independent dataset GSE83453 (AUC = 0.986). Immune cell infiltration research revealed that B cell naive, B cell memory, plasma cells, NK cell activated, monocytes, and macrophage M0 may be involved in the development of AVC. Additionally, all diagnostic characteristics may have varying degrees of correlation with immune cells. The most promising small molecule medicines for reversing AVC gene expression are Doxazosin and Terfenadine.

CONCLUSION

It was identified that CXCL16, GPM6A, BEX2, S100A9, and SCARA5 are potentially beneficial for diagnosing and treating AVC. A diagnostic model was constructed based on a molecular prognostic score system using machine learning. The aforementioned immune cell infiltration may have a significant influence on the development and incidence of AVC.

Antihistamines in children and adolescents: A practical update

Histamine is a chemical mediator, released predominantly by tissue mast cells, circulating basophils, and neurons, which are activated in response to various immunological and non-immunological stimuli. Histamine has to bind to specific receptors to exert its physiological and pathophysiological functions. Endogenous histamine is the main mediator of the immediate allergic response, which moreover, performs other multiple functions, including regulation of gastric secretion, neurotransmission in the central nervous system, and immunomodulatory activity. The involvement of histamine in various disorders and the importance of receptors in the clinical features have relevant implications in clinical practice. Anti-H1 antihistamines contrast the histamine-dependent effects, mainly concerning nasal symptoms and cutaneous itching and wheal. Antihistamines are among the most prescribed drugs in pediatric care. This review updates the practical use of antihistamines in children and adolescents.

To prevent the allergic disease: the dream of the allergist

Allergen avoidance, allergen immunotherapy, IgE antagonists, biological medications, prevention and treatment of respiratory infections, probiotics, adapted formula, vitamins, and oligo-elements have been investigated as strategies in the prevention of allergic diseases. Promising findings were obtained. To prevent allergic diseases could be a dream that will be soon realized in clinical practice.

Lertal®, a multicomponent nutraceutical, could reduce the use of antihistamines in children with allergic rhinoconjunctivitis

Antihistamines are the cornerstone treatment of allergic rhinitis (AR). To quantify the antihistaminic consume is particularly relevant in clinical practice, since a remarkable use is usually associated with severe symptoms. The aim of the study was to measure the use of antihistamines in two groups of children suffering from AR. The first group took a course of a nutraceutical (Lertal®) before the observation (active group, AG); a second one was considered as control (control group, CG). Both groups took antihistamines on demand. The children were visited at baseline and after 1 year. The number of days of antihistaminic use was the primary outcome. Children in AG had a significant reduced number of antihistamines use in comparison with CG (p=0.008). In conclusion, the current study showed that a course with a multicomponent nutraceutical could reduce the use of symptomatic antihistamines in children with allergic rhinoconjuncti- vitis.

VAS for assessing the perception of antihistamines use in allergic rhinitis

The quantification of the antihistamines’ consumption is particularly relevant in clinical practice, since their remarkable use is usually associated with severe symptoms. The aim of the study was to measure the visual analogue scale (VAS) for assessing the patient’s perception about antihistamines use in patients with allergic rhinitis. 103 patients (49 males, mean age 35.9 years) with allergic rhinitis due to Parietaria pollen were evaluated retrospectively. They recorded monthly the number of antihistamine tables they took during the pollen season (lasting for about 5 months). There was a strong relationship (r= 0.921 Pearson; p<0.0001) between the number of tablets and the VAS score. The assessment of the perception of the antihistamines use by VAS could be an easy and quick tool in the management of patients with allergic rhinitis in clinical practice. (www.actabiomedica.it)

The role of antihistamines in asthma management

Histamine is an important mediator in airway inflammation. It is elevated in the airways of asthmatic patients and is responsible for many of the pathophysiological features in asthma. Antihistamines block the actions of histamine and also have effects on inflammation which is independent of histamine-H(1)-receptor antagonism. Antihistamines have been shown to have bronchodilatory effects, effects on allergen-, exercise-, and adenosine-monophosphate-challenge testing, and also to prevent allergen-induced nonspecific airways hyperresponsiveness. Clinical studies have shown mixed results, and some studies have reported beneficial effects of azelastine, cetirizine, desloratadine, and fexofenadine on asthma symptoms or physiological measures in patients with asthma. The combination of an antihistamine and a leukotriene receptor antagonist has been shown to have additive effects in certain studies. Antihistamines have also been shown to delay or prevent the development of asthma in a subgroup of atopic children. These data suggest that antihistamines may have beneficial effects in the management of asthma.

Mast cells: novel clinical perspectives from recent insights

Mast cells are still generally viewed as mediators of type I allergic or pseudoallergic reactions. Research over the past 10 years revealed that our view was too small and that mast cells are of key importance in innate immunity and also types II, III and IV adaptive immune reactions. Understanding their role in modulating and amplifying of inflammatory responses provides important insights into the pathogenesis of skin diseases such as psoriasis, atopic dermatitis, bullous pemphigoid or the control of infections. This helps us to understand the course of these diseases, their trigger mechanisms, and, the new role of agents, which can modulate the function of mast cells. These insights will help to develop new therapeutic approaches.

Levocetirizine in persistent allergic rhinitis: continuous or on-demand use? A pilot study

BACKGROUND

Allergic rhinitis is a high-prevalence disease that affects quality of life (QOL), sleep quality and productivity of patients. According to the ARIA initiative, it is classified as intermittent and persistent, the latter being the most troublesome.

METHODS

The aim of this randomized, open-label, 6-month, pilot study was to determine whether levocetirizine 5 mg administered continuously once daily in the morning was better than levocetirizine 5 mg on-demand in symptomatic subjects with persistent allergic rhinitis. Total and individual symptom scores were recorded in a diary card throughout the study. QOL, quality of sleep, nasal cytology, rate of drug intake, and safety were also assessed at pre-defined time-points.

RESULTS

In all, adult patients (31 in each group) were enrolled, of whom 22 dropped out. Both treatment regimens considerably decreased the total and individual symptoms scores from baseline and achieved similar levels up to week 14. Continuous treatment was generally better than on-demand from week 15 onwards, reaching statistical significance from weeks 17 to 21 (from week 19 to 21 for nasal pruritus). Both regimens substantially improved QOL and sleep quality. Both treatments were well tolerated, although the on-demand group reported more adverse events.

CONCLUSION

The present open label study in 62 patients indicates that levocetirizine 5 mg reliably controls persistent rhinitis over a period of 6 months, and shows a trend to be more effective in controlling the symptoms of rhinitis, improving QOL and decreasing nasal inflammation, when administered as long-term continuous therapy rather than as on-demand therapy.

The effect of H1 antagonists carebastine and olopatadine on histamine induced expression of CC chemokines in cultured human nasal epithelial cells

BACKGROUND

CC chemokines have been shown to play an important role in inducing selective recruitment of inflammatory cells into local allergic inflammatory sites. CC chemokines are also known as histamine releasing factors. We previously showed that histamine enhances transcription of CC chemokines from nasal mucosa which leads to further induction of histamine release. This cyclic cascade may cause prolonged allergic inflammation. The aim of this study is to clarify the relationship between histamine and CC chemokine production by using human nasal epithelial cells (HNECs) and to examine the potential of H1 receptor (H1R) antagonists in new therapeutic approaches for the treatment of nasal allergy.

METHODS

HNECs were isolated from the nasal turbinates of patients diagnosed with nasal allergy. HNEC monolayers were cultured for 48 hours with or without histamine (10(-3) to 10(-5) mol/L). Furthermore, an H1R antagonist, either carebastine or olopatadine, was added to the supernatant (10(-3) to 10(-7) mol/L) 30 minutes before incubation with histamine. The expression of Regulated on Activation, Normal T-cell Expressed and Secreted (RANTES) and monocyte chemotactic protein-1 (MCP-1) in the culture media were measured by ELISA.

RESULTS

The release of RANTES and MCP-1 was significantly upregulated by histamine compared with the control group. Both carebastine and olopatadine inhibited the release of CC chemokine production to the control level in both groups.

CONCLUSIONS

This study suggests that the interaction between histamine and CC chemokines may prolong allergic inflammation in human nasal mucosa. We also demonstrate the potential use of H1R antagonists in new therapeutic approaches to the treatment of nasal allergy through inhibiting this histamine-CC chemokine interaction.

The type of sensitizing allergen can affect the evolution of respiratory allergy

BACKGROUND

Numerous factors affect the evolution of respiratory allergy, in children, but little is known in adults. We assessed in a prospective study the influence of the type of allergen on the progression of disease.

METHODS

Outpatients, with respiratory allergy underwent skin tests and pulmonary function/methacholine challenge at baseline and after 3 years. Patients were subdivided in pure rhinitis or rhinitis + bronchial hyperreactivity (BHR). In polysensitized subjects a single relevant allergen (mites, grasses, birch, Parietaria) was identified based on symptom distribution and when needed on nasal challenge.

RESULTS

6750 patients (age range 12-46) were studied. Of them, 17.8% were monosensitized but this percentage decreased to 10.4% after 3 years (P < 0.05). Subjects with pure rhinitis were 81% at the beginning and 48% at the end. After 3 years, the patients with bronchial responsiveness increased from 18% to 58% for mites, 22% to 49% for birch, 18% to 44% for grasses, 17% to 32% for Parietaria, with a significant difference among allergens (P < 0.05). Almost the same was seen in monosensitized subjects, being mites most likely to cause a worsening. All patients with BHR at baseline received immunotherapy. In these patients the onset of new sensitizations was significantly lower than in the group (pure rhinitis) receiving drugs only and lower airways symptoms disappeared more frequently.

CONCLUSION

The different type of allergen influences the course of the disease, as well as the use of immunotherapy.

Levocetirizine in persistent allergic rhinitis and asthma: effects on symptoms, quality of life and inflammatory parameters

Background Levocetirizine (LCZ) has been shown to be effective in allergic rhinitis. We evaluated its clinical efficacy, antinflammatory actions and its effects on quality of life (QoL) with a specific instrument in the asthma-rhinitis comorbidity. Methods Fifty adult patients with persistent rhinitis with/without asthma were enrolled. After a 1-week run-in for baseline evaluation, they were randomized to LCZ or placebo for 8 weeks. Cromolyn and salbutamol were permitted on demand. Rhinoconjunctivitis and asthma symptoms were evaluated by diary cards. QoL was assessed by the specific Rhinasthma questionnaire and the generic SF-36 at different time-points. Nasal scrapings and lavages were also performed for inflammatory cell count and mediator assessment. Results Ten patients dropped out for unrelated reasons and the remaining completed the study with no side-effect. Symptoms began to decrease in the active group at the second week of treatment when the difference with the placebo group became significant (0.05) and so remained until the end of the trial. Starting from 2 weeks of therapy, there was a significant decrease vs. baseline in all the four components of the Rhinasthma questionnaire only in the active group. The intergroup comparison became significant (P<0.05) at 4 weeks. The SF-36 detected only sporadic differences between groups. Eosinophils and neutrophils in nasal scraping were significantly decreased in the LCZ group vs. baseline at all times. Nasal mediators were under the detection limits and no analysis could be performed. In the active group, only two patients used rescue medications compared with 13 patients in the placebo group. Conclusions LCZ is clinically effective and capable of improving the rhinitis-asthma-related QoL.

Comparison of intranasal corticosteroids and antihistamines in allergic rhinitis: a review of randomized, controlled trials

For several years there has been discussion of whether first-line pharmacological treatment of allergic rhinitis should be antihistamines or intranasal corticosteroids. No well documented, clinically relevant differences seem to exist for individual nonsedating antihistamines in the treatment of allergic rhinitis. Likewise, the current body of literature does not seem to favor any specific intranasal corticosteroid. When comparing efficacy of antihistamines and intranasal corticosteroids in allergic rhinitis, present data favor intranasal corticosteroids. Interestingly, data do not support antihistamines as superior in treating conjunctivitis associated with allergic rhinitis. Safety data from comparative studies in allergic rhinitis do not indicate differences between antihistamines and intranasal corticosteroids. Combining antihistamines and intranasal corticosteroids in the treatment of allergic rhinitis does not provide additional beneficial effects to intranasal corticosteroids alone. Considering present data, intranasal corticosteroids seem to offer superior relief in allergic rhinitis, when compared with antihistamines.

Effects of fexofenadine on T-cell function in a murine model of allergen-induced airway inflammation and hyperresponsiveness

There is renewed interest in antihistamines for the treatment of allergic asthma. A growing body of literature has shown that the newer compounds can affect inflammatory cell accumulation and cytokine/chemokine production. In a murine model of allergen-induced airway inflammation and hyperresponsiveness, the ability of fexofenadine to affect these outcomes was tested in a primary sensitization and challenge model and after treatment of donor mice before the adoptive transfer of T cells into recipients receiving limited allergen exposure. Mice were sensitized and challenged with allergen (ovalbumin). Airway function after inhaled methacholine was monitored in parallel to the assessment of tissue and airway inflammation and cytokine production. In further experiments, lung T lymphocytes from sensitized/challenged donor mice were transferred into naive recipients before limited airway challenge with the allergen. Administration of fexofenadine before challenge but after sensitization was effective in preventing tissue eosinophilia and airway hyperresponsiveness. Moreover, the treatment of donor mice with fexofenadine before transfer of lung T cells effectively prevented airway hyperresponsiveness and eosinophilia in naive mice exposed to limited airway challenge. These data therefore support the potential for fexofenadine in the treatment of allergen-induced airway hyperresponsiveness and inflammation.

Effects of fexofenadine and other antihistamines on components of the allergic response

Intercellular adhesion molecules (ICAMs), in particular ICAM-1, appear to play a crucial role in the recruitment and migration of inflammatory cells to the site of an allergic reaction. Glucocorticoids and allergen-specific immunotherapy have been shown to exert effects on selected components of this system, both in vitro and in vivo, but further research is required to better understand the effects of these therapies. Nasal and conjunctival challenge models (including natural and experimental allergen exposure) represent useful and safe tools for studying the activity of antiallergy drugs in vivo. These tests allow the investigation of a wide variety of parameters including inflammatory infiltrate, ICAM-1 expression, and changes in the concentration of soluble inflammatory mediators. With these tools, anti-inflammatory activity related to the modulation of epithelial cell adhesion molecules has been demonstrated in vivo for several H(1)-receptor antagonists (azelastine, cetirizine, loratadine, levocabastine, oxatomide, and terfenadine). Fexofenadine is a nonsedating, long-acting antihistamine with highly selective H(1)-receptor antagonist activity and a particularly favorable safety profile. In addition, fexofenadine has proven anti-inflammatory activity and has been shown to inhibit a number of mediators at clinically relevant concentrations, including in vitro inhibition of ICAM-1 expression on conjunctival and nasal epithelial cells.

Desloratadine: a nonsedating antihistamine

OBJECTIVE

To review information on desloratadine, a nonsedating antihistamine.

DATA SOURCES

An English-language MEDLINE search was conducted (1966-July 2002). References of identified articles were subsequently reviewed for additional data. Schering Corporation provided unpublished information.

STUDY SELECTION/DATA EXTRACTION

Articles and abstracts pertaining to desloratadine were considered for inclusion, with emphasis on randomized, placebo-controlled, double-blind trials.

DATA SYNTHESIS

Desloratadine is approved for the treatment of symptoms associated with seasonal allergic rhinitis (SAR), perennial allergic rhinitis (PAR), and chronic idiopathic urticaria (CIU) in patients aged > or =12 years. In placebo-controlled trials, desloratadine demonstrated superior efficacy as a once-daily treatment of SAR, PAR, and CIU. Data suggest that desloratadine has antiinflammatory and decongestant activity.

CONCLUSIONS

Desloratadine appears to be a "me-too" agent, with no major differences compared with other second-generation antihistamines.

The effect of ketotifen on inflammatory markers in allergic conjunctivitis: an open, uncontrolled study

BACKGROUND

The efficacy and safety of ketotifen eye drop treatment in allergic conjunctivitis (AC) management is perfectly known by several studies, but the mechanism of action at the biochemical levels is poorly understood so we decided to perform an open, uncontrolled study in order to investigate the effect of the topical administration of ketotifen fumarate 0.05% on biochemical markers of inflammation on conjunctival cells in patients with AC.

METHODS

Nineteen patients with symptoms and signs of AC (itching, discharge, burning, redness, increase in the watery discharge, swelling and follicles) and with a history of allergy were prescribed with two daily instillation of one drop of eyewash ketotifen fumarate 0,05% in both eyes during thirty days. They were studied by measuring clinical and immunologic parameters.

RESULTS

Ketotifen fumarate treatment significantly reduced the total symptoms and signs score for each patient as well as each symptoms and signs at all time points compared with day 0 (p < 0.0001 and p < 0.016, respectively). Although the percentage of HLA-DR+ epithelial cells diminished only in 58% of patients, the numbers of CD29+ and eotaxin+ epithelial cells dropped significantly in 68% and 73 % of them (p < 0.0062 and <0.0082, respectively) as a consequence of the treatment. In 9 out of 19 patients a simultaneous decrease in the percentage of epithelial cells positive for CD29 and eotaxin was observed.

CONCLUSION

Ketotifen besides the well-known effect in reducing signs and symptoms of AC significantly diminished production of eotaxin and expression of CD29 by epithelial cells in patients with seasonal AC.

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.

Evaluation of cytokines in nasal secretions after nasal antigen challenge: lack of influence of antihistamines

BACKGROUND

Previous studies of inflammation in allergic rhinitis using nasal irrication have been unsatisfactory because of 1) poor reproducibility; 2) the tendency of irrigation to overdilute mediators; and 3) the failure of this technique to evaluate interstitial concentrations of relevant mediators. For this study we used filter paper as a matrix to collect nasal secretions in patients undergoing nasal antigen challenge.

OBJECTIVE

To evaluate inflammatory mediators of allergen-induced rhinitis during a clinical trial of fexofenadine.

METHODS

Subjects evaluated at a referral medical center were placed on traditional dosing of fexofenadine at 60 mg, twice daily, or placebo in a double-blind, crossover fashion for 1 week before the nasal challenge. Nasal challenge was performed with nasal insufflation of either 1,000 AU timothy or 0.1 mL ragweed (1:100 wt/vol) extract outside the pollen season. Nasal secretions were collected at baseline and then at 2, 4, and 6 hours after nasal challenge. Secretions were evaluated for expression of the cellular adhesion molecule-1, tumor necrosis factor (TNF)-alpha, interleukin (IL)-4, IL-10, macrophage inflammatory protein (MIP)-1alpha, and granulocyte-macrophage colony-stimulating factor (GM-CSF) using commercially available enzyme-linked immunoadsorbent assay kits. Patients' symptom scores were evaluated during the nasal challenge.

RESULTS

Significantly (P < 0.05) increased peak levels of TNF-alpha, IL-4, IL-10, and MIP-1alpha were detected after antigen challenge as compared with baseline levels. There was a nonsignificant trend toward an increase in GM-CSF after antigen challenge (P = 0.07). There was no difference in the peak levels of TNF-alpha, IL-4, IL-10, MIP-1alpha, or GM-CSF measured when patients were on fexofenadine versus placebo. Finally, there were no significant differences in patients' symptom scores during antigen challenge when subjects were on fexofenadine versus placebo.

CONCLUSIONS

Collection of nasal secretions using a filter paper matrix provides a reproducible model for accurately detecting and evaluating changes in cytokine levels after nasal challenge. Cytokine levels tend to peak 3 to 4 hours after antigen challenge. Standard doses of fexofenadine do not seem to have a mitigating effect on the production of these cytokines. Symptoms of allergic rhinitis using this type of antigen challenge did not differ from treatment with fexofenadine versus placebo.

New insights into the second generation antihistamines

Second generation antihistamines are recognised as being highly effective treatments for allergy-based disease and are among the most frequently prescribed and safest drugs in the world. However, consideration of the therapeutic index or the benefit/risk ratio of the H1 receptor antagonists is of paramount importance when prescribing this class of compounds as they are used to treat non-life threatening conditions. There are many second generation antihistamines available and at first examination these appear to be comparable in terms of safety and efficacy. However, the newer antihistamines in fact represent a heterogeneous group of compounds, having markedly differing chemical structures, adverse effects, half-life, tissue distribution and metabolism, spectrum of antihistaminic properties, and varying degrees of anti-inflammatory effects. With regard to the latter, there is growing awareness that some of these compounds might represent useful adjunct medications in asthma therapy. In terms of safety issues, the current second generation grouping includes compounds with proven cardiotoxic effects and others with the potential for adverse drug interactions. Moreover, some of the second generation H1 antagonists have given cause for concern regarding their potential to cause a degree of somnolence in some individuals. It can be argued, therefore, that the present second generation grouping is too large and indistinct since this was based primarily on the concept of separating the first generation sedating compounds from nonsedating H1 antagonists. Although it is too early to talk about a third generation grouping of antihistamines, future membership of such a classification could be based on a low volume of distribution coupled with a lack of sedating effects, drug interactions and cardiotoxicity.

Antiallergic effects of H1-receptor antagonists

The primary mechanism of antihistamine action in the treatment of allergic diseases is believed to be competitive antagonism of histamine binding to cellular receptors (specifically, the H1-receptors), which are present on nerve endings, smooth muscles, and glandular cells. This notion is supported by the fact that structurally unrelated drugs antagonize the H1-receptor and provide clinical benefit. However, H1-receptor antagonism may not be their sole mechanism of action in treating allergic rhinitis. On the basis of in vitro and animal experiments, drugs classified as H1-receptor antagonists have long been recognized to have additional pharmacological properties. Most first-generation H1-antihistamines have anticholinergic, sedative, local anaesthetic, and anti-5-HT effects, which might favourably affect the symptoms of the allergic response but also contribute to side-effects. These additional properties are not uniformly distributed among drugs classified as H1-receptor antagonists. Azatadine, for example, inhibits in vitro IgE-mediated histamine and leukotriene (LT) release from mast cells and basophils. In human challenge models, terfenadine, azatadine, and loratadine reduce IgE-mediated histamine release. Cetirizine reduces eosinophilic infiltration at the site of antigen challenge in the skin, but not the nose. In a nasal antigen challenge model, cetirizine pretreatment did not affect the levels of histamine and prostaglandin D2 recovered in postchallenge lavages, whereas the levels of albumin, N-tosyl-L-arginine methyl ester (TAME) esterase activity, and LTs were reduced. Terfenadine, cetirizine, and loratadine blocked allergen-induced hyperresponsiveness to methacholine. In view of the complexity of the pathophysiology of allergy, a number of H1 antagonists with additional properties are currently under development for allergic diseases. Mizolastine, a new H1-receptor antagonist, has been shown to have additional actions that should help reduce the allergic response. In animal models, mizolastine inhibits antigen-induced eosinophil infiltration into mouse skin and into the nasal cavity of guinea-pigs. Mizolastine also significantly inhibits antigen-induced neutrophil infiltration into the bronchoalveolar lavage fluids of guinea-pigs. In addition, it inhibits arachidonic acid-induced paw oedema in rats without affecting carrageenin-induced rat paw oedema, suggesting an effect on LT generation. In man, mizolastine inhibits early and late antigen-induced soluble intercellular adhesion molecule 1 (ICAM-1) levels in skin blisters. It also inhibits anaphylactic release of histamine from rodent mast cells, LTC4 and LTB4 release from mouse bone-marrow-derived mast cells, LTC4 release from rat intestinal mast cells, and 5-lipoxygenase activity of polymorphonuclear neutrophils of guinea-pig intestines and rat basophilic leukaemia cells. It is clear that a number of H1-antihistamines have multiple effects on the allergic inflammatory response. It is equally clear that these antiallergic effects are not uniformly shared among all drugs of this class. The assessment of the clinical significance of these results and research regarding the parts of the molecules responsible for these activities are underway.

Nonsteroidal antiallergic treatments in allergic rhinitis

Allergic rhinitis is characterized by an inflammatory reaction consequent to an initial IgE-dependent mast cell activation. The conventional treatment is mainly based on antihistamine and topical corticosteroid prescriptions. In this article the authors consider the antiallergic-antiinflammatory activity exerted by some nonsteroidal drugs or immunologic treatments. Clinical and experimental evidence demonstrates that these treatments are able to control allergic inflammation in patients with allergic rhinitis. In conclusion, treatment of allergic rhinitis may also be based on the prescription of nonsteroidal drugs with antiallergic activity.

Effects of H1 antihistamines on adhesion molecules: a possible rationale for long-term treatment

Our knowledge of the mechanisms underlying the allergic reaction has increased rapidly and has revealed a complex network of cells, mediators and cytokines. The intercellular adhesion system (and the ICAM-1 molecule in particular) appeared to play a pivotal role in the accumulation of inflammatory cells at the site of allergic reaction. The new antihistamines have been demonstrated to be capable of affecting several phenomena of the allergic inflammation, including mediator release, cellular activation and adhesion molecule expression. Taking into consideration the central role of adhesion molecules, the modulation of their expression may represent an important therapeutic target. The nasal and the conjunctival challenges represent two useful models for the in vivo study of the antiallergic activity of drugs, as they allow investigation of a wide variety of parameters: inflammatory infiltrate, ICAM-1 expression, concentration of soluble mediators.

Terfenadine and fexofenadine reduce in vitro ICAM-1 expression on human continuous cell lines

BACKGROUND

Epithelial cells and fibroblasts play an important role in allergic inflammation. Modulation of surface expression of adhesion molecules on epithelial cells by antiallergic drugs has been shown by both in vivo and in vitro studies.

OBJECTIVE

The aim of the study was to evaluate the effect exerted by terfenadine and fexofenadine on adhesion molecules expression (CD54/ICAM-1 and CD29) of a human continuously cultured conjunctival epithelial cell line (WK) and a fibroblast cell line (HEL).

METHODS

By means of flow cytometry analysis, we evaluated ICAM-1 and CD29 expression by WK and HEL epithelial cells in basal condition (at baseline) or after IFN gamma or TNF alpha stimulation in the presence or in the absence of terfenadine and fexofenadine. We also performed immunoenzymatic assays in order to evaluate soluble ICAM-1 released by WK cells and procollagen type I and III and IL6 released by HEL cells.

RESULTS

Terfenadine and fexofenadine significantly reduced ICAM-1 basal expression on WK cells at the concentration of 1 microg/mL and 50 microg/mL, respectively. In addition, both terfenadine and fexofenadine were able to decrease soluble ICAM-1 levels in IFN gamma-stimulated WK cells. On HEL fibroblasts, fexofenadine only was able to inhibit ICAM-1 upregulation induced by IFN gamma. Concerning the release of fibroblast products, we observed a dose-dependent decrease of spontaneous IL6 release only in the presence of fexofenadine.

CONCLUSION

This study shows that terfenadine and fexofenadine exert a biologic effect directly on epithelial cells and fibroblasts reducing ICAM-1 expression and partially reducing soluble ICAM-1 release.

Executive summary

Allergic rhinitis is now recognized as a major cause of morbidity that significantly impairs function and quality of life. Moreover, it is now widely held that the pathophysiologic mechanisms causing nasal allergy contribute, or predispose many individuals, to the development of other airway diseases, including asthma. Allergic rhinitis may well be a factor in 24% of children with otitis media with effusion (OME), and perhaps 28% of cases of chronic sinusitis. As many as 78% of persons with asthma aged 15 to 30 years have elevated serum IgE antibodies to five common aeroallergens. In many instances, nasal allergy signals the presence of more severe disease.

Considerable evidence now suggests that early and appropriate intervention can improve the quality of life and productivity of patients with allergic rhinitis, enhance the academic performance of children, and reduce the prevalence of airway complications. The goal of treatment has shifted from mere symptom alleviation to blocking the pathophysiologic mechanisms that cause chronic allergic inflammation and leave patients vulnerable to airway infections. The earlier in a patient's life that this can be accomplished, the better the anticipated consequences.

A panel of experts was convened in Amsterdam, The Netherlands, on 2 September 1996, to explore these issues and their impact on allergy prevention and treatment in primary care. Their undertaking was supported by an unrestricted educational grant from Schering‐Plough Pharmaceuticals.

Continuous versus on demand treatment with cetirizine for allergic rhinitis

BACKGROUND

Cetirizine is an antihistamine used in the treatment of allergic rhinoconjunctivitis, that has antiallergic activity.

OBJECTIVE

The aim of this double-blind, placebo-controlled, parallel group study was to evaluate the clinical efficacy and the antiallergic activity of cetirizine, administered either continuously or on demand over a 4-week period of natural allergen exposure.

METHODS

Twenty patients, with allergic rhinoconjunctivitis due to grass and/or Parietaria pollen, were enrolled. They were randomized into 2 parallel groups: one group received the standard dose of 10 mg cetirizine daily and the other received placebo, all patients were allowed to take an additional daily dose of cetirizine when needed. Variables evaluated were clinical symptoms (recorded on diary cards), number of additional on demand cetirizine doses, nasal inflammatory cells, and pollen counts.

RESULTS

The results of the present study show that patients treated with continuous administration of cetirizine achieved significant symptomatic relief and inflammatory control (decreases in numbers of infiltrating neutrophils and eosinophils) in comparison to patients treated on demand.

CONCLUSION

Continuous treatment with cetirizine is more effective than on demand treatment. Continuous treatment reduces clinical and inflammatory variables more than symptomatic treatment and the on demand therapy can determine acceptable clinical control, but does not reduce allergic inflammation.

Reduction of soluble ICAM-1 levels in nasal secretion by H1-blockers in seasonal allergic rhinitis

ICAM-1, a transmembrane glycoprotein promoting adhesion in immunologic and inflammatory reactions, was found to be increased on nasal epithelial cells of patients with allergic rhinitis. Loratadine, an H1-blocker, was found to reduce in vitro the expression of ICAM-1 on nasal epithelial cells. A double-blind, parallel-group study was carried out during the pollen season to compare the effect of two H1-blockers, cetirizine (10 mg OD) and loratadine (10 mg OD), on the release of soluble ICAM-1 in nasal secretions. A group of untreated patients was used as a control group. sICAM-1 was measured by enzyme immunoassay before and after 2 weeks of treatment. Symptoms were significantly decreased in the actively treated groups. sICAM-1 levels were unchanged in the control group but were significantly reduced in the two treated groups (P < 0.015, Wilcoxon's W test). This study shows that two H1-blockers, loratadine and cetirizine, have a similar effect on sICAM-1 released in nasal secretions during the pollen season.

Molecular events in allergic inflammation: experimental models and possible modulation

In recent years, a complex molecular network involving cytokines kinins and adhesion molecules has been demonstrated to operate in allergic inflammation. In particular, the adhesion machinery plays a crucial role for the recruitment and locomotion of the inflammatory cells and the Intercellular Adhesion Molecule 1 (ICAM-1) is a hallmark of the allergic inflammatory process. The role and possible modulation of ICAM-1 can be investigated using both eye and nose experimental models. Conjunctival and nasal epithelium are easy to study either under natural allergen exposure or after specific/aspecific provocation tests; furthermore the nasal/conjunctival challenge is well tolerated by the patients. These experimental models have allowed us to investigate in vivo the antiallergic properties of several compounds. Many of the new antihistamines, but also deflazacort and local nasal immunotherapy, were demonstrated capable of reducing both inflammatory infiltration and ICAM-1 expression on epithelia. Because of the central role of adhesion molecules in allergic inflammation, their pharmacological modulation can be regarded as a promising therapeutic approach.