Ocular allergic disease

Increased expression of Filaggrin and Claudin-1 in the ocular surface of patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is an itchy, chronic and inflammatory skin condition, with dysfunctional immune response and skin barrier defects. Reduction of filaggrin (FLG) and tight junctions (TJ) proteins, such as claudin-1 (CLDN-1), expression in cutaneous epithelial barrier is remarkable in AD pathogenesis. Ocular involvement occurs in approximately 40% of AD patients leading to changes in the structure of the conjunctiva.

OBJECTIVES

We aimed to evaluate the expression of FLG and CLDN-1 in the ocular surface of adults with AD, analysing bulbar conjunctival cells collected by a novel non-invasive cellular imprint.

METHODS

Bulbar conjunctival epithelial cells were collected by cellular imprint technique, and FLG and CLDN-1 expression were assessed by immunofluorescence (IF) and real-time polymerase chain reaction (RT-PCR).

RESULTS

We detected increased expression of FLG and CLDN-1, as well as their transcript levels in AD patients compared with healthy controls (HC). There was a positive correlation between tear film break-up time (TBUT) and FLG expression. Fluorescein staining was inversely associated with FLG expression.

CONCLUSIONS

Our results may reflect a reactive response of the ocular surface to AD-related ocular inflammation and associated dry eye disease. Further investigations focusing on the role of FLG and TJ expression in the ocular surface of AD patients may increment the understanding of the pathophysiology of extracutaneous AD and developing future targeted therapies.

Comparative profile of ocular surface microbiome in vernal keratoconjunctivitis patients and healthy subjects

PURPOSE

To compare ocular surface microbiome and its antibiotic sensitivity in vernal keratoconjunctivitis (VKC) with normal ocular surface.

METHODS

In this case-control study, thirty patients each with clinical diagnosis of VKC and age-matched controls with normal ocular surface were enrolled. Tear film samples were collected from each group and subjected to microbial evaluation with microscopy, conventional culture methods, and polymerase chain reaction (PCR). Microbial diversity and antibiotic sensitivity patterns were analyzed.

RESULTS

Most patients (67%) belonged to severe grades (3 and 4) of VKC, and allergic history could be elicited in 20%. On culture, bacteria were isolated in 50% of VKC patients and 47% of control group. Staphylococcus species were identified in 70% VKC group and 57% control group. S. aureus growth was seen in 52% and 21% of VKC patients and controls, respectively. S. pneumoniae was isolated only in controls (29%) (p<0.05). Confluent colonies (≥10 colonies/μl) were seen in 70% of VKC patients and 14% of controls (p<0.05). Fluoroquinolone resistance was more among higher grades of VKC (50%) (p<0.01) and was observed in 46% of VKC patients and 23% of control group (p<0.01). Both groups were negative for HSV-1 DNA and fungal growth.

CONCLUSION

Staphylococcus, the most common ocular surface flora, was predominant in VKC patients. Microbial analysis revealed similar microbial diversity in both groups. However, bacterial load was higher in VKC. Increased fluoroquinolone resistance was observed in VKC patients with more resistance among higher grades. Fungi and HSV-1 were not seen in VKC or normal ocular surface.

Impression cytology for detection of clinically suspected ocular surface disorders: A cross-sectional study

PURPOSE

Investigating impression cytology (IC) results of various types of clinically suspected ocular surface lesions over a 14-year period in a referral center in Iran.

METHODS

IC findings obtained from patients with different types of ocular surface disorders between 2005 and 2018 were reviewed. Agreement between clinical suspicions and IC results was evaluated by calculating Cohen's Kappa coefficient (CKC).

RESULTS

Clinical suspicions in 688 surveyed eyes were ocular surface squamous neoplasia (OSSN, 42.0%), limbal stem cell deficiency (LSCD, 36.3%), dry eye-related disorders (DERD, 11.5%), Acanthamoeba keratitis (AK, 7.2%), benign pigmented lesions (BPL, 1.9%), immune-related conjunctivitis (IRC, 0.7%), and malignant pigmented lesions (MPL, 0.4%). General agreement between clinical suspicions and IC results was 0.68 for all groups. This agreement was almost perfect in AK (CKC = 0.966) and BPLs (CKC = 0.843), and was substantial in MPLs (CKC = 0.749), OSSNs (CKC = 0.684), and LSCD (CKC = 0.612). CKC in IRC (0.567) and DERDs (0.443) was moderate. Histopathologic results were available in 22 eyes and were well-correlated with corresponding IC results (CKC = 0.86). Multiple post-treatment follow-up sessions of IC were performed in 51 eyes (11.4%) that had diagnosis of LSCD (31), OSSN (17), and MPL (3) at the first IC session.

CONCLUSION

Our survey not only demonstrated an overall substantial agreement between IC results and primary clinical suspicions, but also showed an almost perfect correlation between IC results and existent histopathologic data. Therefore, IC as a non-invasive diagnostic modality can be of great importance in proper diagnosis of various ocular surface diseases especially when distinguishing malignant from benign lesions is required.

Sympathetic Nerves Positively Regulate Eosinophil-Driven Allergic Conjunctivitis via α1-Adrenergic Receptor Signaling

Eosinophils are a major cause of tissue injury in allergic conjunctivitis. The biological nature of eosinophils in the conjunctiva and the mechanisms that control eosinophils' responses in allergic conjunctivitis are currently not completely understood. This study reports that conjunctival eosinophils comprise two populations-Siglec-F^int and Siglec-F^hi-in different life stages. Siglec-F^int eosinophils partly expressed CD34 and were in the immature (or steady) state. Siglec-F^hi eosinophils did not express CD34, sharply increased in number after short ragweed (SRW) pollen challenge, and were in the mature (or activated) state. Moreover, chemical sympathectomy by 6-hydroxydopamine reduced the recruitment and activation of eosinophils, whereas the activation of the sympathetic nerve system (SNS) with restraint stress accelerated the recruitment and activation of eosinophils in SRW-induced conjunctivitis. It was also found that two eosinophil populations expressed alpha-1a-adrenergic receptors (α1a-ARs); in SRW-induced conjunctivitis, treatment with an α1a-AR antagonist decreased eosinophil responses, whereas treatment with an α1a-AR agonist aggravated eosinophil responses. Thus, eosinophil responses in conjunctivitis are regulated by the SNS via α1a-AR signaling. SNS inputs or α1a-AR function may be potential targets for the treatment of allergic conjunctivitis.

Therapeutic effects of topical 0.03% Tacrolimus ointment in children with refractory vernal keratoconjunctivitis in Middle East

OBJECTIVE

The purpose of this paper is to review the efficacy and safety profile in children treated with topical 0.03% Tacrolimus ointment for vernal keratoconjunctivitis in Middle East and to propose a treatment posology. According to recent studies, a complex non-IgE dependent mechanism plays a relevant role in the pathogenesis of vernal keratoconjunctivitis. Numerous cells and mediators have been found in the serum, conjunctiva and tears of patients with Vernal keratoconjunctivitis.

DESIGN

This case series included 10 patients from a single centre, pediatric department of a tertiary hospital with active symptomatic vernal keratoconjunctivitis. All the patients had proliferative lesions and corneal involvement despite conventional medications, including topical steroids. All other medications, systemic and topical: steroids, antihistamines and cyclosporine, were unsuccessful. Patients were treated with topical 0.03% Tacrolimus ointment twice daily for 8 weeks and then once a day for the next two month followed by thrice a week for two months. The changes in symptoms and signs after treatment were evaluated, also the development of possible complications was assessed.

RESULTS

The results showed a significant reduction in signs and symptoms after 4 weeks of the treatment. Clinical resolution of giant papillae and corneal lesions were seen within eight weeks and no additional drug was required during that period, except tear substitutes. Treatment was continued for period of two months and then slowly reduced.

CONCLUSION

The use of 0.03% Tacrolimus ointment is safe and effective in children refractory to conventional treatment of vernal keratoconjunctivitis even in high temperature climate as Middle East. Due to the effectiveness of the treatment, the dosage used may be proposed for conventional use.

MiR-146a overexpression effectively improves experimental allergic conjunctivitis through regulating CD4+CD25-T cells

OBJECTIVE

To study the mechanism of miR-146a in the regulation of allergic conjunctivitis (AC) through CD4⁺CD25^-T cells.

METHODS

BALB/c mice were sensitized with ragweed pollen (RW) and alum, and then challenged with RW. Eosinophil infiltration was determined using Giemsa assay. ELISA assay was performed to examine the level of antigen-specific IgE in the serum and cytokine levels in splenocytes. The expression of miR-146a was measured by qRT-PCR. Flow cytometric analysis was used to analyze the percentage of CD4⁺CD25^-T cells and Tregs.

RESULTS

In this study, we found that miR-146a overexpression could effectively improve the symptoms of AC in mouse models. Moreover, in vitro experiments, the proliferation of splenocytes was controlled and the expression of IL-5 and IL-13 was also decreased after transfected with miR-146a mimic. In addition, the inhibitory effect of Tregs on Tcons was affected by the change of miR-146a content in Tcons and had a positive correlation effect. When the content of miR-146a in Tregs changed, the inhibition was not affected. In addition, when inhibited miR-146a, NF-κB signaling pathway was activated, and the expression of IL-5 and IL-13 in Tcons increased. While after added Bay (NF-κB blocker), the NF-κB activity was decreased, and the expression of IL-5 and IL-13 in Tcons also reduced.

CONCLUSION

MiR-146a decreased in Tcons was contributed to the development of AC through regulating the inhibitory effect of Tregs on Tcons and NF-κB signaling pathway.

Long-term use of 0.003% tacrolimus suspension for treatment of vernal keratoconjunctivitis

PURPOSE:

To evaluate the safety and efficacy of 0.003% tacrolimus suspension for the treatment of refractory vernal keratoconjunctivitis (VKC).

MATERIALS AND METHODS:

This prospective study included 40 eyes of 20 patients with severe VKC. After discontinuing all other medications, patients were treated with varying doses of 0.003% tacrolimus suspension. All were followed for at least 24 months. Changes in signs and symptoms after treatment were evaluated; adverse events were assessed. The clinical response to the treatment was the most important measurement to achieve the conclusion.

RESULTS:

The mean age of the patients was 15.7 ± 1.4 years. Two patients discontinued treatment due to severe burning sensation and were excluded from the study. Significant improvements in all signs and symptoms, including itching, foreign body sensation, papillae, and Trantas dots, were seen in all patients 6 weeks after starting topical tacrolimus. Itching was the first symptom to improve. Treatment was gradually reduced, and intervals were increasing between applications. Recurrence occurred in all patients who attempted to discontinue treatment. No additional medications were required to provide relief, and no significant changes in visual acuity or refraction were seen.

CONCLUSIONS:

The safety and efficacy of 0.003% Tacrolimus suspension treatment for refractory VKC were achieved and it can be considered a useful option instead of steroids, despite the poor compliance in few patients due its adverse effects.

Tacrolimus Ointment for Treatment of Vernal Keratoconjunctivitis

Purpose:

To evaluate the safety and efficacy of tacrolimus 0.1% ointment for the treatment of refractory vernal keratoconjunctivitis (VKC).

Materials and Methods:

This prospective, nonrandomized case series enrolled 20 patients (40 eyes) with severe VKC, who were treated with tacrolimus 0.1% ointment. The mean age of the patients was 18.25 ± 4.2 years (range, 9–31 years). Each patient completed a follow-up period of at least 24 months. The main outcome measure was the clinical response to treatment.

Results:

Significant improvements in clinical signs and symptoms were achieved in all patients 6 weeks after starting treatment with topical tacrolimus. Treatment was gradually reduced, with increasing intervals between applications. VKC recurred in all patients who attempted to discontinue treatment. No additional medications were required and no significant changes in visual acuity or refraction were documented. Five patients discontinued treatment due to a severe burning sensation and were excluded from the study.

Conclusions:

Tacrolimus, 0.1% ointment, is a safe and effective treatment for VKC refractory to standard treatment and may be used as a substitute for steroid treatments used to controlled disease activity. However, adverse effects could cause poor patient compliance.

Eyelash Length in Children with Vernal Keratoconjunctivitis: Effect of Treatment with Cyclosporine Eye Drops

The upper eyelashes in vernal keratoconjunctivitis (VKC) patients have been reported to be longer than in healthy age- and gender-matched subjects. Eyelash length positively correlated to the severity of the disease and negatively to the employment of cyclosporine eye drops, suggesting that specific humoral factors could be involved in both ocular inflammation and elongation of the eyelashes. The aim of the present study is to evaluate a possible relationship between eyelash length and the duration of topical cyclosporine treatment. The length of the upper eyelashes of 34 VKC patients never treated with topical cyclosporine (Cyc-NT) was matched with that of 58 VKC patients treated with cyclosporine (Cyc-T). The latter group was divided into three subgroups, depending on the duration of therapy: 1–6 months (group 1; 21 subjects), 7–12 months (group 2; 19 subjects), >12 months (group 3; 19 subjects). Cyc-NT patients' eyelashes were significantly longer than those of VKC patients treated for 1–6 months (group 1). No significant difference was found between Cyc-NT and Cyc-T patients in group 2 and group 3. The differences between Cyc-T patients and group 1 and 2, group 2 and 3, and group 1 and 3 were not statistically significant. The eyelash shortening observed seems directly related to the rapid improvement of ocular symptoms induced by the treatment. A receptor down-regulation by mediators of ocular inflammation may explain this data, although different cytokines, hormones or other humoral mediators could be expressed on the ocular surface at different stages of the disease, mainly in periods of rapid change of the clinical course.

Is there is an association between the presence of Staphylococcus species and occurrence of vernal keratoconjunctivitis?

Purpose

The aim of this study was to identify the association of normal bacterial flora with vernal keratoconjunctivitis (VKC) occurrence in VKC and non-VKC groups.

Methods

Conjunctival specimens were collected from 18 VKC patients and 22 healthy controls, cultured and identified following standard methods. The association between the presence of bacteria and occurrence of VKC was analyzed using Chi square statistic.

Results

Comparable bacterial growth was observed in VKC (77.8%) as well as control group (77.2%) (p = 0.970). Analysis of individual bacterial revealed that Staphylococcus aureus was detected more frequently in VKC (27.78% vs. 4.55% in control, p = 0.041) and Staphylococcus epidermidis was found much more commonly in the control eyes (45.45% in control vs. 5.56% in VKC, p = 0.005).

Conclusions

An aggravating role of S. aureus colonization in the occurrence of VKC, and a possible role of S. epidermidis against the occurrence of VKC were concluded.

Alpha-1 antitrypsin, a diagnostic and prognostic marker of vernal keratoconjunctivitis

INTRODUCTION

A major chunk of ocular allergies in humans involve the conjunctiva, of which Vernal Keratoconjunctivitis (VKC) appears to be more common. VKC, a chronic allergic conjunctivitis, frequently affects young males and is characterized by intense inflammation of the limbal and/or tarsal conjunctiva. The etiology and immuno-pathogenesis of VKC still remain unclear. Alpha-1 antitrypsin (AAT), a member of serine proteinase inhibitor (SERPIN) superfamily, is an acute phase protein whose concentration in blood increases in response to inflammation. AAT deficiency is one of the many factors that may be involved in several abnormalities such as liver disease, emphysema, inflammatory joint diseases and inflammatory eye diseases. In the present study, the role played by this protein in VKC was analyzed in a selective case/control study to assess its diagnostic and prognostic value.

MATERIALS AND METHODS

The case control study included 50 patients of VKC reporting to Ophthalmology out patient department (OPD). Age and sex matched 40 healthy subjects served as control. Serum AAT level of both the cases and controls were evaluated and compared. Moreover the serum AAT levels of the patients at presentation were compared with their serum AAT level after three weeks post treatment.

RESULT

Levels of AAT in the serum of VKC patients at presentation (2.80 ± 0.42 mg/ml) were significantly higher as compared to controls (2.31 ± 0.21 mg/ml) whereas no significant difference was observed between the serum level of post treatment VKC patients (2.48 ± 0.26 mg/ml) and controls.

CONCLUSION

AAT is a potent acute phase protein whose concentration rises significantly in VKC, irrespective of the age and sex of the patient. Moreover, the serum level of AAT declined significantly post treatment; therefore it might be used as a prognostic marker.

Epidemiology of ocular allergy and co-morbidities in adolescents

OBJECTIVE

The prevalence of allergic conjunctivitis (AC) has not been established. Estimates suggest that ocular allergies affect 15% to 20% of the worldwide population, yet most epidemiological studies encompass nasal and ocular allergy symptoms and have not been specific to AC. The aim of this study was to verify the prevalence of ocular allergy symptoms, co-morbidities, and their impact on adolescents.

METHODS

Adolescents were selected from a sample of schools, and completed in classrooms a previously validated questionnaire on symptoms of AC. AC diagnosis was considered when more than three episodes of ocular itching were reported in the past 12 months. Related symptoms such as tearing, photophobia, foreign body sensation, impact on daily activities, and diagnosis of AC were analyzed.

RESULTS

Questionnaires were obtained from 3,120 adolescents (mean age 13.3±1.1 years). Ocular itching in the past 12 months occurred in 1,592 (51%). The most frequently associated symptom was tearing (74%), followed by photophobia (50.1%) and foreign body sensation (37.1%). The prevalence of AC was 20.7%, affecting more females than males (56.1% versus 45.9%; p= 0.01). The risks of an adolescent with ocular allergy to present asthma, rhinitis, and atopic eczema were (OR= 5.7; 95% CI: 4.5 to 7.1), (OR=3.6; 95% CI: 3.0 to 4.3), and (OR=2.6; 95% CI: 2.0 to 3.5), respectively. Severe interference in daily activities was reported by 30.5%.

CONCLUSIONS

Symptoms of ocular allergy are common, frequently associated to other allergic diseases, and impact the daily activities of adolescents.

Molecular immunology of allergic conjunctivitis

PURPOSE OF REVIEW

Successful treatment of allergic eye disease depends on understanding the pathophysiology of ocular allergy. Thus, in this review, recent experimental and clinical research that has provided significant information about the immunopathology of allergic eye disease will be discussed.

RECENT FINDINGS

Recently, role of various cells, cytokines and chemokines has been scrutinized in the immunopathogenesis of ocular allergy. In this respect, current research highlights contribution of special molecules and cells in the development and clinical features of immunoglobulin E (IgE) and T-cell-mediated eye allergies.

SUMMARY

Recent findings in molecular immunology of ocular allergy, which comprise complex inflammatory conditions of the conjunctiva, have enabled us to better understand the pathophysiology of these diseases and have aided in the potential development of new therapeutic agents.

Management of seasonal allergic conjunctivitis: guide to therapy

Seasonal allergic conjunctivitis (SAC) is an inflammatory response of the conjunctiva triggered by exposure to seasonal allergens. Treatment options for SAC include artificial tears, antihistamines, decongestants, mast cell stabilizers, nonsteroidal anti-inflammatory drugs, dual antihistamine/mast cell stabilizers, immunotherapy and corticosteroids. Topical, intranasal and systemic formulations of corticosteroids have traditionally provided the most effective relief of the inflammation and signs and symptoms associated with severe, acute exacerbations of SAC. However, steroid-induced ocular and systemic side-effects have limited the prescribing of these agents. This limitation of traditional corticosteroids led to the development of modified corticosteroids that retain the anti-inflammatory mechanism of action of traditional corticosteroids with a much-improved safety profile because of their rapid breakdown to inactive metabolites after exerting their activity. The development of one such novel corticosteroid, loteprednol etabonate (LE), led to the insertion of an ester (instead of a ketone) group at the carbon-20 (C-20) position of the basic corticosteroid structure. Clinical trials assessing this C-20 ester corticosteroid have demonstrated similar efficacy to C-20 ketone corticosteroids in the prevention or treatment of the signs and symptoms of SAC but with a greatly improved safety profile, as the C-20 ester corticosteroid is less likely to elevate intraocular pressure. In addition, the ketone at the C-20 position has been implicated in the formation of cataract, while nonketolic corticosteroids do not form Schiff base intermediates with lens proteins, which is a common first step in cataractogenesis. The clinical relevance of the C-20 ester corticosteroid class, as modelled by LE, is that they provide both effective and safe treatment of the inflammation associated with SAC and relief of its signs and symptoms. Loteprednol etabonate offers a well-tolerated treatment option for patients with debilitating acute exacerbations as well as chronic forms of the disease.

The role of histamine in ocular allergy

Ocular allergy is a disorder affecting increasing numbers of individuals worldwide. Among the inflammatory mediators that contribute to ocular allergy, histamine is perhaps the best characterized. This monoamine is released by sensitized mast cells upon exposure to allergen and causes symptoms such as redness and tearing. Histamine may also recruit immune cells that can cause long-term damage to ocular surfaces. In this chapter we will discuss the known functions of histamine and histamine receptors in ocular allergy and will describe promising therapies targeting the histamine-signaling pathway.

Cytokines and chemokines in immune-based ocular surface inflammation

Altered levels of several cytokines and chemokines have been found in different types of inflammatory ocular surface diseases, such as allergy or dry-eye syndrome. It has also been demonstrated that epithelial cells play a key role in the persistence and even initiation of chronic mucosal inflammation. The recent development of 'multiplex detection' technologies has facilitated the identification of specific patterns of expression of these molecules in some ocular immune-based inflammatory disorders. Analysis of these molecules in tissues, cells (in vivo and in vitro) and tears has revealed that not only inflammatory cells but also epithelial and fibroblast resident cells are sources of these molecules. The purpose of this review is to summarize recent studies in this field.

Contribution of IL-33 to induction and augmentation of experimental allergic conjunctivitis

IL-33, a member of the IL-1 family of cytokines, is the ligand for ST2 (IL-33Ralpha chain). IL-33 has the capacity to induce T(h)2 cytokine production from T(h)2 cells, mast cells and basophils, indicating that IL-33 has the potential to induce T(h)2 cytokine-mediated allergic inflammation of the eye. Thus, we tested the pathological role of IL-33 in allergic conjunctivitis (AC). As reported elsewhere, animals immunized with ragweed pollen (RW)/alum and boosted with RW/PBS developed AC promptly (within 15 min) and conjunctival eosinophilic inflammation after a delay (within 24 h) in response to eye drop challenge with RW. Furthermore, RW-immunized mice, when topically challenged with both RW and IL-33, developed more striking eosinophilia in their conjunctiva without exacerbation of the clinical AC score. This in vivo IL-33 treatment significantly increased the capacity of T cells in the cervical lymph nodes of RW-immunized mice to produce IL-4, IL-5 and IL-13 upon challenge with anti-CD3 and anti-CD28 antibodies in vitro. Furthermore, the infiltrating cells were largely eosinophils and a small proportion of CD4(+) T cells, both of which express ST2. We also found that even splenic eosinophils express ST2 and show increased expression in response to IL-5, granulocyte-macrophage colony-stimulating factor (GM-CSF) or IL-33. Eosinophils, stimulated with IL-5 and/or GM-CSF, are responsive to IL-33, which induces production of IL-4 and chemokines. Finally, we showed that conjunctival tissues constitutively express biologically active IL-33, suggesting that IL-33 might play a crucial role in the induction and augmentation of AC.

Seasonal and perennial allergic conjunctivitis: the possible role of nasal allergy

BACKGROUND

There is a link between conjunctiva and nose. Nasal allergy is suspected to be involved in some cases of conjunctivitis. This work aims to investigate the possible role of nasal allergy in seasonal (SAC) and perennial (PAC) allergic conjunctivitis and the value of nasal challenges with allergens (nasal provocation tests [NPTs]) for the diagnostic procedures of the conjunctivitis.

METHODS

In 61 adults suffering from SAC or PAC with a positive history and skin tests, but responding insufficiently to the local treatment, 122 NPTs and 61 control nasal challenges with phosphate-buffered saline (PBS) were performed using rhinomanometry combined with recording of ocular response. In 16 control subjects suffering only from allergic rhinitis without a history of conjunctivitis, 16 positive NPTs were repeated and supplemented with registration of ocular features.

RESULTS

Of the 61 patients, 55 developed 103 positive nasal responses of various types (P < 0.01), 82 of which were accompanied by significant conjunctival response (P < 0.01) without any corneal involvement. No significant ocular responses were recorded during 61 control PBS challenges (P > 0.05) as well as during 16 challenges in control subjects (P > 0.1).

CONCLUSIONS

These results illustrate a possible involvement of nasal allergy in some patients with allergic conjunctivitis (SAC and PAC) and the value of the nasal challenges with allergen combined with registration of the ocular features in the diagnostic approach to these disorders.

Mast Cell Chymase Decreases the Barrier Function and Inhibits the Migration of Corneal Epithelial Cells

PURPOSE

We investigated the in vitro effects of human mast cell chymase on corneal epithelial cells.

METHODS

Human corneal epithelial cells were incubated with human chymase at activity levels that were likely to exist in the tears of patients with vernal keratoconjunctivitis.

RESULTS

Incubation of chymase resulted in a decrease of barrier function of corneal epithelium. Occludin protein was cleaved by chymase. In the wound assay, incubation with chymase resulted in an inhibition of cell migration.

CONCLUSION

Human chymase causes the proteolysis of occludin and fibronectin, resulting in a decrease of barrier function and inhibition of the migration of corneal epithelial cells.

Immune regulatory mechanisms in allergic conjunctivitis: insights from mouse models

PURPOSE OF REVIEW

This review highlights recent findings regarding the immune regulation of allergic conjunctivitis. Mouse models have facilitated prospective studies that have not been possible in patients. The availability of gene knockout mice and the wealth of monoclonal antibodies have permitted exquisite dissection of the pathophysiology and immune regulation of allergic conjunctivitis.

RECENT FINDINGS

New insights have emerged in three areas: role of costimulatory molecules in the induction of Th2 immune responses; crucial role of IFN-gamma in the expression of allergic conjunctivitis; and the function of T regulatory cells in shaping conjunctival inflammation once the immune response has been initiated.

SUMMARY

Allergic conjunctivitis involves early phase and late phase reactions. The early phase reaction is IgE antibody-dependent, whereas the late phase reaction is IgE-independent and is mediated by inflammatory cells, especially eosinophils. Recent studies on mouse models of allergic conjunctivitis have provided important insights into the immune regulation of both the early phase reaction and late phase reaction of allergic conjunctivitis. Mounting evidence suggests that IFN-gamma is crucial for optimum expression of allergic conjunctivitis. Costimulatory molecules influence the induction of Th2 immune responses and the early phase reaction, whereas regulatory T cells shape the expression of the late phase reaction of allergic conjunctivitis.

Serum allergen specific immunoglobulin E levels in patients with allergic conjunctivitis

PURPOSE

To evaluate serum allergen specific immunoglobulin E (IgE) levels in patients with various types of allergic conjunctivitis.

METHODS

Twenty-five patients with seasonal allergic conjunctivitis (SAC), 17 patients with perennial allergic conjunctivitis (PAC), and 10 patients with vernal conjunctivitis (VC) were included in the study. Specific IgE levels to Dermatophagoides pteronyssinus (Dp), Dermatophagoides farinae (Df), mixed grass pollens, and animal epithelia were measured using Pharmacia CAP system (Pharmacia Diagnostic AB, Uppsala, Sweden).

RESULTS

The percentage of subjects with specific IgE against Dp and Df was statistically higher in VC (30%) compared to PAC (5.9%) and SAC (0%) (p=0.03). Specific IgE against mixed grass pollens was found in 30% of VC and 40% of SAC, whereas 10% of VC and 8% of SAC patients were found to be hypersensitive to animal epithelia.

CONCLUSIONS

Allergic reaction against house dust mites and pollens was common in VC, whereas specific IgE against grass pollens was remarkable in SAC. IgE levels specific to various antigens might be measured by UNICAP system, which is a rapid and practical technology.

Cytokine responses by conjunctival epithelial cells: an in vitro model of ocular inflammation

OBJECTIVES

We examined the differential secretion of cytokines by a conjunctival epithelial cell line in response to proinflammatory cytokines to identify the potential contributions during ocular surface inflammation.

METHODS

A conjunctival epithelial cell line was exposed to IFN-gamma, TNF-alpha, IL-4, or IL-13, and cytokine production was determined in supernatants at different times after exposure. Cell apoptosis was measured by flow cytometry.

RESULTS

TNF-alpha induced the greatest effect on cytokine secretion, which was time-dependent. TNF-alpha-stimulated secretion of IL-12p40 was significantly increased by 30 min; GM-CSF, MCP-1, IL-6, IL-7, IL-8, and RANTES were significantly increased by 2 h, and IFN-gamma and IL-1alpha by 24 h. After 48 h, TNF-alpha also induced a significant increase in IL-1beta, IL-3, and IP-10 secretion. IFN-gamma significantly enhanced IP-10 and RANTES secretion after 48 h of exposure. Following IL-4 treatment there was a significant increase in eotaxin-1 after 24h, and IL-12p40 and IL-3 after 48 h. IL-13 significantly increased the secretion of eotaxin-1 after 24 h, and IL-8 after 48 h.

CONCLUSION

Our results suggest that conjunctival epithelial cells are an important source of cytokines and chemokines that are regulated by proinflammatory cytokines and may play an important role in ocular surface inflammation.

Pharmacotherapy of allergic eye disease

Allergic eye disease is a term that refers to a number of disease processes that affect about one-fifth of the world's population. Although the more advanced forms of the disease can be sight threatening, the most disabling effects are due to the clinical manifestations, and hence quality of life, with some patients having seasonal exacerbations of their symptoms, whereas others have symptoms that are present throughout the year. Recent increased understanding of the cellular and mediator mechanisms that are involved in the various disease manifestations has greatly facilitated the development of more effective treatment options. Newer topical medications are being used that have multiple actions, such as an antihistaminic effect coupled with mast-cell stabilisation, and which require reduced daily dosing due to their longer duration of action. With greater research into newer therapies and more effective modes of delivery, improved healthcare outcomes with a lower economic burden will be achieved for patients with allergic eye disease.

Clinical grading of atopic keratoconjunctivitis

PURPOSE OF REVIEW

Atopic keratoconjunctivitis (AKC), the most severe and chronic form of ocular surface allergy-related disorder, is the ocular surface complication that some atopic dermatitis patients can suffer. Its wide range of severity, from mild and occasional problems to persistent and intense inflammation, makes it difficult to appropriately select uniform patients for clinical studies. This article proposes a new classification system for AKC based on clinical severity.

RECENT FINDINGS

Recent reports on AKC have contributed to a better understanding of the pathogenesis and clinical manifestations, and are offering new therapeutic candidates for AKC. No reports, however, have been found that address a classification of this disease.

SUMMARY

A new definition and classification for AKC is presented by this review, based on clinical severity, grading the main symptoms and signs. It intends to serve as a first forum of discussion among clinicians and other scientists working in the field of ocular surface inflammation. The final intention is to have a common language helping develop efficient clinical trials leading to successful approval of new therapeutic compounds for this blinding ocular surface condition.

IL-10 confers protection from mast cell degranulation in a mouse model of allergic conjunctivitis

IL-10 is a regulatory cytokine known to inhibit allergic and inflammatory events. Mast cells (MC) are effector cells which when stimulated release histamine, chemokines and cytokines that initiate the allergic inflammatory response. Recent studies have shown that IL-10 regulates MC function by affecting cytokine production and expression of FcvarepsilonR1 in in vitro assays. Using IL-10 knockout (IL10KO) mice, we examined the effect of its absence on MC susceptibility to degranulation by the basic secretagogue, Compound 48/80 (C48/80). C48/80 is a receptor mimetic that directly activates G proteins and stimulates vigorous MC degranulation. For these studies we stimulated conjunctival MC with C48/80 and found that conjunctival MC of IL10KO mice exhibit increased degranulation compared with wild type mice. Reconstitution of IL10KO mice by adding rIL-10 24h prior to challenge with C48/80 conferred increased resistance of MC to the degranulatory effects of C48/80. The protective effect therefore appears to be due to the presence of IL-10. This is the first in vivo rodent study which reports a novel role of IL-10 in stabilizing mast cells from degranulation by a secretagogue, by as of yet an unknown mechanism.

Omalizumab: a future innovation for treatment of severe ocular allergy?

Conjunctival and corneal manifestations of atopic keratoconjunctivitis (AKC) are chronic, disabling and may be blinding. In common with other allergic diseases, such as asthma and atopic dermatitis, AKC is characterised by an allergen-induced immune response mediated through expression of IgE. The humanised monoclonal IgE antibody Xolair (omalizumab) complexes with free circulating IgE, thereby preventing binding of IgE to FcepsilonRI receptors on immune cells. Omalizumab effectively alleviates the signs and symptoms of asthma. Given the pivotal role of IgE in the allergic cascade, it is hypothesised that omalizumab has potential as an entirely new therapeutic approach to AKC.

Toll-like receptors and the eye

PURPOSE OF REVIEW

This review will describe the structure, expression/distribution and functional activity of Toll-like receptors, in particular in the ocular structures. It will also discuss innate and adaptive immune responses, by exploring the possible modulation/regulation of innate and adaptive immunity by Toll-like receptors, in view of recent findings observed in the ocular surface.

RECENT FINDINGS

Current knowledge indicates that Toll-like receptors represent essential elements in host defence against pathogens, a prerequisite to the induction of adaptive immune responses. The expression/distribution of Toll-like receptors in the healthy eye highlights the possible function of Toll-like receptors in both innate and adaptive responses during pathological conditions of the ocular surface.

SUMMARY

Recent findings have greatly increased the knowledge of the possible role of Toll-like receptors in innate and adaptive immune responses. Toll-like receptors seem to play different roles in a wide range of activities of the immune system, and might represent an exclusive link between innate and adaptive responses under pathological conditions. Recent studies in ophthalmology have highlighted the role of Toll-like receptors in infections (keratitis) as well as in allergic states of the ocular surface. This review thus describes the relationship between Toll-like receptors and the main immune/structural cells taking part in inflammatory disorders. Understanding the complex mechanisms underlying Toll-like receptor localization and function will provide additional data that might help devise novel therapeutic approaches involving Toll-like receptors and their agonists, in an attempt to modulate the biased immune system.

The role of the conjunctival epithelium in ocular allergy

PURPOSE OF REVIEW

The epithelium of target organs is playing an increasing role in allergy. Several studies have shown that epithelial cells participate actively in inflammatory processes. This review will focus on recent advances in the role of conjunctival epithelium in allergy as a potential target for therapeutic interventions.

RECENT FINDINGS

Several studies have already shown the involvement of ocular surface epithelial cells in allergic inflammatory diseases, because they are able to produce and secrete cytokines and chemokines upon stimulation. They also express adhesion molecules as well as receptors for several substances implicated in inflammation. Some studies have also shown that conjunctival epithelial cells express co-stimulatory molecules when they interact with activated T cells, adding more evidence to the important role that epithelial cells play in the pathogenesis of ocular inflammatory diseases. Recent reports have also demonstrated that during inflammatory conditions, conjunctival epithelial cells show an altered expression of their neuroreceptors, suggesting that a modulation of neural regulation may be of therapeutic value.

SUMMARY

The ocular surface epithelium is not just a simple physical barrier to the entrance of foreign bodies. It participates in the allergic inflammatory process by being influenced by inflammatory molecules, and by secreting inflammatory cytokines and chemokines. Moreover, the epithelium not only actively participates in the inflammation process but can also initiate it. This relevant spectrum of actions makes epithelium an attractive target for therapeutic interventions.

[Ocular allergies]

Recent developments indicate that ocular allergy is more than an IgE-mediated allergic conjunctivitis. Ocular allergy is a disease affecting the entire ocular surface including conjunctiva, lids, cornea, lacrimal gland and tear film. Besides an IgE-mediated reaction, a complex chronic inflammation is involved in the pathogenesis of many ocular allergies. According to their pathogenesis and clinical picture, ocular allergies are classified into mild forms, such as seasonal and perennial allergic conjunctivitis as well as giant papillary conjunctivitis, and chronic, potentially blinding forms such as atopic keratoconjunctivitis and vernal keratoconjunctivitis. New therapeutics act on the entire inflammatory process or try to modulate the allergic reaction early and specifically. The association with non-ocular allergic symptoms requires an interdisciplinary approach.