Adhesion molecules and H1-antihistamines

Comparative study of topical anti-allergic eye drops on human conjunctiva-derived cells: responses to histamine and IFNγ and toxicological profiles

BACKGROUND

The purpose of the study was to compare toxic effects and responses to histamine and IFN gamma associated with the use of some widely used anti-allergic eye drops commercially available today.

METHODS

For dynamic studies, the Wong-Kilbourne cell line was stimulated for 24 h with histamine or IFN gamma in the presence or absence of anti-allergic eye drops. Supernatants of histamine-stimulated cells were evaluated for the production of IL-6 and IL-8 by ELISA, while the expression of ICAM-1 was evaluated by flow cytometry on IFN gamma-stimulated cells. Toxicological assays were performed using cold light cytofluorometry: viability and apoptosis as well as reactive oxygen species (ROS) and O2(.)- production were assessed using neutral red, Hoechst/propidium iodide, H(2)-DCFDA and hydroethidine tests, respectively.

RESULTS

Antihistamines reduced IL-6 release and presented dose-dependent inhibitory effects on IL-8 production. None of the eye drops decreased the basal or IFN gamma-stimulated expression of ICAM-1. Conversely, eye drops preserved with benzalkonium chloride (BAC) induced even higher ICAM-1 expression levels on IFN gamma-stimulated cells than did IFN gamma alone, whereas unpreserved drugs had no effect. Toxicological assays confirmed the pivotal role of BAC in proportionally reducing cell viability while increasing apoptosis and oxidative stress.

CONCLUSIONS

The ability of topical ocular anti-H(1) drugs to significantly reduce the production of IL-6 and IL-8 argues that they may help treat the inflammatory processes occurring in allergic ocular surface disorders. Nevertheless, preserved ophthalmic formulations may enhance epithelial conjunctival expression of ICAM-1 in the presence of a low inflammatory stimulus, such as IFN gamma, and displayed toxic as well as pro-oxidative effects on these cells. Therefore, BAC used as preservative might in part interfere with the potential anti-inflammatory properties of the active compound by modulating the immuno-inflammatory response of epithelial conjunctival cells.

Humoral and cellular responses to histamine and pollen allergen in a skin chamber model: effect of mizolastine

BACKGROUND

Mizolastine is a new non-sedative antihistamine and antiallergic drug proven to be effective and safe in the treatment of allergic rhinitis and urticaria.

OBJECTIVE

To quantitatively explore the time course of mediator release and cell recruitment during allergen challenge and the effects of mizolastine on the event, using the skin chamber model.

METHODS

Twelve pollen-sensitive patients (23+/-6 years) were included in a double-blind crossover study. Patients received 10 mg mizolastine or placebo once daily in the first 4-day period and, after a 3-week washout period, vice-versa in the crossover period. On day 4 of each period, a non-invasive in vivo skin chamber technique was used to determine the alteration of vascular permeability, mast cell mediator release, the release of soluble intercellular adhesion molecule -1(sICAM-1) in skin sites challenged with exogenous histamine or grass pollen allergen extract, over an 8-hour period.

RESULTS

Challenge with allergen-induced significant mast cell activation, as indicated by the release of histamine, tryptase and LTC4, in chamber fluids 2 hours after initiation of the allergic reaction and during the following 6 hours. Both exogenous histamine and allergen induced significant vasodilatation, which was sustained during the 8-hour challenge, as indicated by the accumulation of protein in the chamber fluids. Likewise, both histamine and allergen induced the release of significant amounts of ICAM-1 throughout the 8-hour period. Mizolastine significantly inhibited the histamine- and allergen-induced extravasation (after 2 hours, P = .003; after 8 hours, P = .009; after 2 hours, P = .044; after 8 hours, P = .003 respectively) and the histamine- and allergen-induced--ICAM-1 release (after 2 hours, P = .004; after 8 hours, P = .05; after 2 hours, P = .03 respectively).

CONCLUSION

Mizolastine strongly inhibited the local response to histamine in this skin chamber model with, of interest, inhibition of the release of the soluble adhesion-molecule ICAM-1.

Clinical aspects, epidemiology, and prognosis of atopic dermatitis

OBJECTIVE

This review article examines the clinical aspects, epidemiology, and prognosis of atopic dermatitis.

DATA SOURCES

These are studies and review articles from textbooks of dermatitis and allergy in general, as well as more recent epidemiologic surveys published in specialist journals of allergy and dermatology.

STUDY SELECTION

Included studies meet the criteria of being a survey of the prevalence of atopic dermatitis published recently in a respected peer-reviewed journal. Particular emphasis is placed on those that examine both the prevalence of the problem and significant causative and associated factors.

RESULTS

Atopic dermatitis is frequently a severe illness that develops in early infancy. It can persist beyond the childhood years and is often found in association with significant respiratory complications. The exact pathogenesis is unclear but it appears that it has a complex immunologic origin. Early surveys lack the methodologic refinements of more recent data from the mid-1990s, including the SCARPOL study. Collectively, these point to a high current prevalence rate of 10% to 15%, a figure that has risen steadily in the preceding decades. The most common associations of atopic dermatitis are a risk of developing respiratory disorders, such as allergic rhinitis and asthma (40% to 60%), and a persistence rate after puberty (40% to 60%), which is indeed much higher than previously suspected.

CONCLUSIONS

A clear recognition of the various disease subgroups along with intervention studies that evaluate reduction of risk are needed before more precise treatment strategies can be devised.