Antiallergic activity of topical lodoxamide on in vivo and in vitro models

Omalizumab in three children with severe vernal keratoconjunctivitis

Background

Vernal keratoconjunctivitis (VKC) is a rare, recurrent form of ocular allergy that can be refractory to topical and systemic treatment. It typically presents as acute and chronic keratoconjunctival inflammation that may lead to visual impairment due to corneal ulcers and scaring. Patients often suffer from atopic IgE-driven comorbidities, especially atopic eczema. Children are frequently affected and often do not tolerate topical treatment well, especially if photophobia and pain impair therapy adherence. We present three children with severe VKC who were not controlled by first- and second-line topical and systemic therapy and finally responded to treatment with the monoclonal anti-IgE antibody omalizumab as third-line treatment.

Methods and results

We retrospectively analyzed three patients with VKC having failed response to first- and second-line treatment. All three boys had very early allergic rhinoconjunctivitis from age 1–3 with polysensitization: birch, grass pollen, house dust mite, and/or pets. All received subcutaneous or sublingual immunotherapy (SCIT/SLIT) for birch and/or grass pollen without major success. Two patients had comorbidities: allergic asthma and severe atopic dermatitis (AD). For at least 6 months after the first administration, monoclonal anti-IgE antibody omalizumab (150 or 300 mg) was administered subcutaneously every 2–6 weeks in all patients achieving improvement of the clinical grading scale from VKC grade 3–4 to grade 1–2. One patient had a relapse mainly of his AD and achieved complete control of AD and VKC by introduction of dupilumab.

Conclusion

Although the clinical benefit of omalizumab in asthma and chronic spontaneous urticaria (CSU) has been established in several clinical trials, there are very little data about its effect on severe VKC. In addition to few previously reported cases we can report the rapid effectiveness of omalizumab in VKC clinically and in terms of quality of life. Randomized trials are needed to include omalizumab in third-line treatment of VKC for prevention of visual impairment and further sequelae such as corneal damage.

Conjunctival allergen provocation test : guidelines for daily practice

Conjunctival allergen provocation test (CAPT) reproduces the events occurring by instilling an allergen on the ocular surface. This paper is the compilation of a task force focussed on practical aspects of this technique based on the analysis of 131 papers. Main mechanisms involved are reviewed. Indications are diagnosing the allergen(s)-triggering symptoms in IgE-mediated ocular allergy in seasonal, acute or perennial forms of allergic conjunctivitis, especially when the relevance of the allergen is not obvious or in polysensitized patients. Contraindications are limited to ongoing systemic severe pathology, asthma and eye diseases. CAPT should be delayed if receiving systemic steroids or antihistamines. Local treatment should be interrupted according to the half-life of each drug. Prerequisites are as follows: obtaining informed consent; evidencing of an allergen by skin prick tests and/or serum-specific IgE dosages; being able to deal with an unlikely event such as acute asthma exacerbation, urticaria or anaphylaxis, or an exacerbation of allergic conjunctivitis. Allergen extracts should be diluted locally prior to administration. Positive criteria are based on itching or quoted according to a composite score. An alternative scoring is based on itching. CAPT remains underused in daily practice, although it is a safe and simple procedure which can provide valuable clinical information.

Vernal keratoconjunctivitis: a severe allergic eye disease with remodeling changes

Vernal keratoconjunctivitis (VKC) is an unusually severe sight-threatening allergic eye disease, occurring mainly in children. Conventional therapy for allergic conjunctivitis is generally not adequate for VKC. Pediatricians and allergists are often not familiar with the severe clinical symptoms and signs of VKC. As untreated VKC can lead to permanent visual loss, pediatric allergists should be aware of the management and therapeutic options for this disease to allow patients to enter clinical remission with the least side effects and sequelae. Children with VKC present with severe ocular symptoms, that is, severe eye itching and irritation, constant tearing, red eye, eye discharge, and photophobia. On examination, giant papillae are frequently observed on the upper tarsal conjunctiva (cobblestoning appearance), with some developing gelatinous infiltrations around the limbus surrounding the cornea (Horner-Trantas dot). Conjunctival injections are mostly severe with thick mucus ropy discharge. Eosinophils are the predominant cells found in the tears and eye discharge. Common therapies include topical antihistamines and dual-acting agents, such as lodoxamide and olopatadine. These are infrequently sufficient and topical corticosteroids are often required for the treatment of flare ups. Ocular surface remodeling leads to severe suffering and complications, such as corneal ulcers/scars. Other complications include side effects from chronic topical steroids use, such as increased intraocular pressure, glaucoma, cataract and infections. Alternative therapies for VKC include immunomodulators, such as cyclosporine A and tacrolimus. Surgery is reserved for those with complications and should be handled by ophthalmologists with special expertise. Newer research on the pathogenesis of VKC is reviewed in this article. Vernal keratoconjunctivitis is a very important allergic eye disease in children. Complications and remodeling changes are unique and can lead to blindness. Understanding of pathogenesis of VKC may lead to better therapy for these unfortunate patients.

Image analyses of the kinetic changes of conjunctival hyperemia in histamine-induced conjunctivitis in Guinea pigs

BACKGROUND

Conjunctival hyperemia is the most common finding in patients with allergic conjunctivitis. Histamine is a typical chemical mediator involved in allergic conjunctivitis and induces hyperemia. Here, we investigated the kinetic changes in bulbar hyperemia induced by histamine in eyedrops.

METHODS

Male guinea pigs were challenged with histamine in eyedrops. Bulbar conjunctival images were taken every 10 seconds by a digital camera up to 8 minutes after histamine challenge, and the software program ImageJ was used to analyze the images. Images were binarized, and a region of interest unobscured by corneal and scleral vessels was selected as the evaluation area. Evaluations were carried out before and after histamine challenge by counting the numbers of absolute pixel values, percent changes in pixels, or the fractal dimension in acquired images.

RESULTS

After histamine challenge, the conjunctival vessel area continued to increase up to 5 minutes before stabilizing. The various parameters used to evaluate the images (numbers of absolute pixel values, percent change in pixels, or the fractal dimensions) markedly increased 1 minute after histamine challenge, gradually increased up to 5 minutes, and then gradually decreased before reaching a level that remained significantly higher than that before histamine challenge.

CONCLUSIONS

This is the first report to quantitatively evaluate bulbar hyperemia induced by histamine using image analysis. The development of software that can automatically yield meaningful values for hyperemia from hyperemia images will be a useful objective tool in clinical trials for evaluation of drug effects in animal models and in humans.

Myeloperoxidase release after allergen-specific conjunctival challenge

BACKGROUND

Allergen-specific conjunctival challenge is a fruitful and complete tool in evaluating pathophysiological phenomena of allergic inflammation. After challenge, a significant neutrophil infiltrate occurred in allergic subjects. The primary (azurophilic) granules of neutrophils contain a variety of enzymes that might potentiate inflammation, such as myeloperoxidase (MPO). It is not known whether allergen-specific conjunctival challenge (ASCC) is able to elicit MPO release. We also investigated the possible role of immunotherapy (IT) in the release of MPO.

METHOD

The groups studied included Dactylis glomerata-sensitive adult atopic patients suffering from seasonal allergic rhinoconjunctivitis, and healthy adult nonatopic volunteer controls. One group of allergic patients received no specific hyposensitization (not-IT allergic group). A second group of allergic patients had been immunotherapy-treated with Dactylis glomerata extract for the preceding three years and continued to receive a maintenance dose within the highest potency of the extract (IT-allergic group). ASCC with Dactylis glomerata was performed outside the pollen season in all subjects. Myeloperoxidase was assayed by MPO-enzyme immunoassay method.

RESULTS

Thirty minutes after challenge, myeloperoxidase levels in the non-immunotherapy allergic patients were significantly higher compared than in the healthy group (p<0.001). The levels of myeloperoxidase released in the immunotherapy allergic group were significantly lower than those in the nonimmunotherapy allergic group (p<0.001) and higher than those in nonallergic subjects (p<0.001).

CONCLUSION

These results indicate that after ASCC there is a release of MPO. Our study suggests that immunotherapy actively modifies the release of MPO after ASCC.

Conjunctival provocation testing: overview of recent clinical trials in ocular allergy

PURPOSE OF REVIEW

The conjunctival provocation test is a human model of ocular allergy that has been used to study the ocular response to allergenic stimuli and to evaluate antiallergic therapy. The review will discuss recent studies using the conjunctival provocation test and other models of ocular allergy, and evaluate the relative merits of different models.

RECENT FINDINGS

The conjunctival provocation test has allowed investigators to recruit large numbers of allergic individuals who, although asymptomatic, can be challenged with the conjunctival administration of allergen. Observations of the eye can be made before and after challenge, and cells and mediators may be sampled from the ocular surface. In addition, the effectiveness of antiallergic therapy can be evaluated, usually by pretreating the two eyes with different forms or doses of drug.

SUMMARY

Considerable useful information has been gained about the ocular allergic response and drug efficacy using the conjunctival provocation test and naturally occurring seasonal allergic conjunctivitis.

Ocular allergy: causes and therapeutic options

Ocular allergic eye conditions are among the most common anterior eye problems encountered in optometric practice. There are six common forms of ocular allergy: seasonal allergic conjunctivitis, perennial allergic conjunctivitis, vernal keratoconjunctivitis, atopic keratoconjunctivitis, contact lens associated papillary conjunctivitis and contact ocular allergy. Here, we review the current understanding of the pathophysiology underlying ocular allergic conditions and describe the different causes and forms of allergic eye disease and different treatment options.