The eosinophil and the eye

Management of vernal keratoconjunctivitis: Navigating a changing treatment landscape

Vernal keratoconjunctivitis (VKC) is a chronic, progressive, and potentially sight-threatening form of ocular inflammatory disease that primarily affects children and young adults. Prevalence varies by region, ranging from <2 per 10,000 in the United States to as high as 1,100 per 10,000 in parts of Africa. The rarity of VKC in developed countries can make differential diagnosis challenging, and treatment is often delayed until the disease is advanced, and symptoms are significantly impacting patients' quality of life. Although once viewed primarily as an immunoglobulin E-mediated condition, approximately 50% of patients with VKC do not exhibit allergic sensitization. It is now recognized that the immunopathology of VKC involves multiple inflammatory pathways that lead to the signs, symptoms, and conjunctival eosinophilic and fibroproliferative lesions that are a hallmark of the disease. We examine the evolution of our understanding of the immunopathology of VKC, the expanding VKC treatment armamentarium, the clinical implications of emerging treatment approaches, and future directions for VKC research and practice.

Role of Damage-Associated Molecular Patterns (DAMPs/Alarmins) in Severe Ocular Allergic Diseases

Severe ocular allergic diseases, such as atopic keratoconjunctivitis and vernal keratoconjunctivitis, cause severe allergic inflammation in the conjunctiva and corneal epithelial damage, resulting in visual disturbances. The involvement of damage (danger)-associated molecular patterns (DAMPs/alarmins) in the pathogenesis of these diseases has been recognized. Alarmins released from damaged corneal epithelial cells or eosinophils play a critical role in the induction of corneal lesions, vicious loop of corneal injury, and exacerbation of conjunctival allergic inflammation. Alarmins in the conjunctiva also play an essential role in the development of both allergic inflammation, based on the acquired immune system, and type 2 inflammation by innate immune responses in the ocular surface. Therefore, alarmins may be a potentially important therapeutic target in severe refractory ocular allergic diseases.

Understanding Vernal Keratoconjunctivitis: Beyond Allergic Mechanisms

Vernal keratoconjunctivitis (VKC) is a chronic, recurrent, inflammatory disease of the cornea and conjunctiva mostly affecting boys in prepubertal age. VKC recurrence is characterized by intense symptoms of itching, redness, and photophobia associated with corneal damage, impairment of visual function, and quality of life. The pathogenesis of VKC has not yet been completely understood, and it is still controversial. In fact, VKC is considered an ocular allergic disease due to the involvement of immunoglobulin E, eosinophils, and mast cells, and of a lymphocyte T-helper type 2 reaction. However, approximately half of VKC patients have negative allergological history and testing, suggesting that other pathogenic mechanisms participate in VKC development and severity. Specifically, evidence suggests that genetic, endocrine, neuronal factors and an imbalance of innate immunity are involved in the pathogenesis of VKC. The purpose of this review is to summarize evidence on the pathogenic role of innate immunity, neuroimmune reaction, and hormonal changes in VKC. Increasing understanding of the pathogenic mechanisms behind VKC may lead to the identification of novel biomarkers for diagnosis and/or potential therapeutic targets in order to improve the management of this challenging condition.

Adult vernal keratoconjunctivitis

PURPOSE OF REVIEW

Vernal keratoconjunctivitis (VKC) is a rare chronic self-limiting allergic inflammatory disease of the ocular surface mostly affecting young boys in their first decade of life. In the last few years a new clinical entity of VKC has been described: adult VKC. Two variants have been identified according to clinical onset: early (childhood VKC persisting beyond puberty) and late onset (arising de novo in adults) adult VKC. Several epidemiologic studies on VKC have been published from single tertiary centers but while the age distribution of VKC patients does show a small percentage of adults with the disease, detailed analysis on this small subset of adult VKC cases is lacking. In this review we describe pathogenesis, clinical features, diagnostic alternatives, and therapeutic alternatives of this highly invalidating disease.

RECENT FINDINGS

Adult variants of VKC have same clinical manifestations of classic form, but show higher inflammatory response and increased risk of chronic fibrotic sequelae.

SUMMARY

Adult VKC research could provide insights on the impact of sex hormones in the pathogenesis of allergic diseases and on the mechanisms of inflammation and fibrosis, which cause potentially vision threatening sequelae. The present review will highlight the recent developments in our understanding of this uncommon entity.

Rupatadine: efficacy and safety of a non-sedating antihistamine with PAF-antagonist effects

Rupatadine is a modern non-sedating H1-antihistamine that also haswith additional antagonist effects on platelet-activating factor (PAF). Under the tradenames Rupafin® and Urtimed®, Rrupatadine is approvedregistered in Germany for the treatment of allergic rhinitis and urticaria infor adults and children aged over 12 years. In this review, the available literature available to date onregarding the pharmacological profile and clinical application of Rrupatadine is reviewed and compared to other conventional histamines. In conclusionFinally, the side effects, safety and interaction profileincompatibility of Rrupatadine are discussed. Due to CYP p450 metabolism, Rrupatadine should not be given together with Eerythromycin, Kketoconazole or grapefruit juice. Rupatadine has been found to be effective and safe Iin a variety of randomized clinical trials both in both seasonal and perennial allergic rhinitis, as well as inbut also chronic urticaria Rupatadine has been found as effective and safe.

CD8+ T Cells Play Disparate Roles in the Induction and the Effector Phases of Murine Experimental Allergic Conjunctivitis

Although CD4+ Th2 cells clearly play an essential role in the development of experimental allergic diseases, the functions CD8+ T cells may have in these diseases have been investigated less extensively and remain controversial. Here, we investigated the roles of CD8+ T cells in the development of experimental allergic conjunctivitis (EC). EC was induced in CD8alpha-deficient (CD8KO) mice and wild-type (WT) mice by active immunization with short ragweed pollen (RW) followed by challenge with RW-containing eye drops. Alternatively, EC was induced by transferring RW-primed splenocytes followed by RW challenge. With regard to actively immunized mice, CD8KO mice showed significantly less severe eosinophil infiltration of the conjunctiva and lower total IgE levels, although the levels of the other Igs were equivalent between the two strains. Cytokine production by cultured splenocytes also did not differ, but the WT conjunctivas showed upregulated IL-5 and IL-6 expression and greater upregulation of IL-4 expression than the conjunctivas of CD8KO mice. Thus, CD8+ T cells may play a significant role during the induction phase by aiding IgE production and the generation of Th2 cytokines in the conjunctiva, thus promoting the development of EC. In contrast, splenocytes from CD8KO mice induced significantly more severe EC in WT mice than cells from WT mice. In addition, transfer of RW-primed splenocytes induced significantly more severe eosinophil infiltration in CD8KO recipient mice. Thus, CD8+ T cells promote the development of EC during the induction phase, but suppress it during the effector phase.

B and T lymphocyte attenuator regulates the development of antigen-induced experimental conjunctivitis

PURPOSE

To investigate the roles that B and T lymphocyte attenuator (BTLA) and herpesvirus entry mediator (HVEM) play in the development of antigen-induced experimental conjunctivitis (EC).

METHODS

BALB/c mice were immunized with ragweed (RW) in alum. Ten days later, the mice were challenged with RW in eye drops. After 24 hours, the conjunctivas, blood and spleens were collected for histological analysis, measurement of serum immunoglobulin (Ig) levels, and both flow cytometric analysis and cytokine assays, respectively. The mice were injected intraperitoneally with anti-BTLA antibody, anti-HVEM antibody or control antibody during either induction phase or effector phase.

RESULTS

Induction-phase treatment with anti-BTLA antibody but not anti-HVEM antibody significantly increased conjunctival eosinophil infiltration. Treatment with either antibody during the effector phase did not affect conjunctival eosinophil infiltration. Anti-BTLA antibody treatment during the induction phase reduced the B cell compartment and increased the CD11b-positive cell compartment in splenocytes. Additionally, anti-BTLA treatment upregulated IL-4 and IL-10 production of splenocytes stimulated by RW.

CONCLUSIONS

BTLA regulated the development of EC possibly by downregulating Th2 cytokine production and adjusting the compartments of immunocompetent cells. The regulation of EC by BTLA may be mediated by BTLA ligands other than HVEM.

[Allergic mediators in tear from children with seasonal and perennial allergic conjunctivitis]

PURPOSE

To evaluate the concentration of allergic mediators in tears of children with seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC) compared with controls.

METHODS

Twenty children with allergic conjunctivitis (17 SAC, and 3 PAC) and sixteen healthy children were included in this study. Tear samples were collected using a Merocel sponge (Oasis, 0525), and immediately eluted by incubation in elution buffer and subsequent centrifugation at 20,000 rpm for 30 min at 4°C. Concentrations of histamine (HIS), tryptase (TPS), eosinophil chemotactic factor (ECF), major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN), IgE and E-selectin were measured using enzyme linked immunosorbent assays (ELISA). Data were compared with the Mann-Whitney U test (P<.05), and multivariate analyses were also performed.

RESULTS

Tear levels of TPS (P=.014), MBP (P=.032), ECP (P=.0041), IgE (P=.014) and EDN (P=.00077) showed significant differences in children with SAC and PAC compared to controls.

CONCLUSION

The simultaneous analyses of allergic mediators in the tears of children with SAC and PAC showed a significant elevated concentration in EDN, ECP and MBP in allergic group and decreased levels in IgE and TPS. Statistical analyses showed a diagnostic accuracy of 94.4% using the eight molecules panel.

Analysing the eosinophil cationic protein--a clue to the function of the eosinophil granulocyte

Eosinophil granulocytes reside in respiratory mucosa including lungs, in the gastro-intestinal tract, and in lymphocyte associated organs, the thymus, lymph nodes and the spleen. In parasitic infections, atopic diseases such as atopic dermatitis and asthma, the numbers of the circulating eosinophils are frequently elevated. In conditions such as Hypereosinophilic Syndrome (HES) circulating eosinophil levels are even further raised. Although, eosinophils were identified more than hundred years ago, their roles in homeostasis and in disease still remain unclear. The most prominent feature of the eosinophils are their large secondary granules, each containing four basic proteins, the best known being the eosinophil cationic protein (ECP). This protein has been developed as a marker for eosinophilic disease and quantified in biological fluids including serum, bronchoalveolar lavage and nasal secretions. Elevated ECP levels are found in T helper lymphocyte type 2 (atopic) diseases such as allergic asthma and allergic rhinitis but also occasionally in other diseases such as bacterial sinusitis. ECP is a ribonuclease which has been attributed with cytotoxic, neurotoxic, fibrosis promoting and immune-regulatory functions. ECP regulates mucosal and immune cells and may directly act against helminth, bacterial and viral infections. The levels of ECP measured in disease in combination with the catalogue of known functions of the protein and its polymorphisms presented here will build a foundation for further speculations of the role of ECP, and ultimately the role of the eosinophil.

Bepotastine besilate, a highly selective histamine H(1) receptor antagonist, suppresses vascular hyperpermeability and eosinophil recruitment in in vitro and in vivo experimental allergic conjunctivitis models

To elucidate the ocular pharmacological properties of bepotastine besilate, a selective histamine H(1) receptor antagonist, when compared with other histamine H(1) receptor antagonists, using guinea pig allergic conjunctivitis models and in vitro models of eosinophil recruitment and mast cell membrane stabilization. Conjunctival vascular hyperpermeability was studied in guinea pigs passively sensitized with anti-ovalbumin antiserum or following subconjunctival injection of histamine. Modulation of eosinophil recruitment was evaluated for both platelet-activating factor (PAF)-induced eosinophil infiltration in guinea pigs and leukotriene B(4)-induced in vitro chemotaxis of guinea pig peritoneal eosinophils. Membrane-stabilizing effects of bepotastine also were studied with rat peritoneal mast cells stimulated with the ionophore A23187. Histamine H(1) receptor antagonists including bepotastine besilate were topically administered before ovalbumin, histamine or PAF challenges for in vivo experiments or were added directly to mast cell and eosinophil medium in vitro. Bepotastine besilate significantly inhibited conjunctival vascular hyperpermeability in a dose-dependent manner with maximal effect for bepotastine besilate 1.5%. In separate in vivo experiments, bepotastine besilate 1.0% was significantly more effective than levocabastine 0.025% in the passive sensitization model or olopatadine 0.1% in the histamine-induced hyperpermeability model. Bepotastine besilate 1.0% further suppressed PAF-induced eosinophil infiltration into conjunctival tissue more effectively than ketotifen 0.05%. Chemotaxis of guinea pig peritoneal eosinophils and histamine release from rat peritoneal mast cells in vitro were also inhibited by addition of bepotastine. Olopatadine had a weak effect as compared to that of bepotastine on eosinophil chemotaxis and no effect on mast cell histamine release in our study conditions. Bepotastine besilate was more potent than olopatadine, ketotifen, or levocabastine in reducing vascular hyperpermeability in various animal models of allergic conjunctivitis. Mast cell function and eosinophil chemotaxis were also inhibited in vitro with bepotastine, suggesting bepotastine acts as an inhibitor of allergic response through multiple mechanisms: histamine H(1) receptor antagonism, mast cell stabilization, and inhibition of eosinophil migration to ocular inflammatory sites.

Notch ligand Delta-like4 inhibits the development of murine experimental allergic conjunctivitis

BACKGROUND

To investigate the involvement of Notch ligands in the development of experimental allergic conjunctivitis (EC) in mice.

METHODS

To induce EC, wild-type (WT) or IFN-gamma-deficient (GKO) BALB/c mice were immunized with ragweed (RW) in alum followed by RW challenge in eye drops. Twenty-four hours after RW challenge, the conjunctivas, spleens and blood were harvested to evaluate conjunctival eosinophil infiltration, RW-specific cytokine production and serum Ig levels, respectively. Abs against Notch ligands (anti-Jagged1, anti-Jagged2, anti-Delta-like (Dll)1 and anti-Dll4) were injected intraperitoneally into EC-developing mice during the induction or effector phase. As a control, normal hamster IgG (nhIgG) was injected.

RESULTS

Treatment with anti-Dll4 Ab but not the other Abs during the induction phase significantly augmented the severity of EC, as measured by the conjunctival eosinophil infiltration. Anti-Dll4 Ab treatment also significantly upregulated RW-recall IL-4 production and suppressed serum IgE and IgG1 levels. However, anti-Dll4 Ab treatment during the induction phase did not significantly affect the severity of EC in GKO mice. None of the Abs significantly affected the severity of EC, splenocyte cytokine production, or serum Ig levels when administered during the effector phase.

CONCLUSIONS

These observations suggest that Dll4, a Notch ligand, plays a role in suppressing the development of EC, possibly by providing a negative signal for Th2 development during the induction phase. In addition, IFN-gamma may participate in the augmentation of EC by anti-Dll4 Ab treatment.

Alterations of the ocular surface epithelial MUC16 and goblet cell MUC5AC in patients with atopic keratoconjunctivitis

BACKGROUND

An increased understanding of the ocular surface at cellular level in the conjunctiva and the cornea may help explain the pathogenesis and the subsequent clinical appearance of atopic ocular allergies, which may be potentially blinding.

PURPOSE

To investigate the MUC16 and MUC5AC alterations, tear function and the ocular surface disorder in patients with atopic keratoconjunctivitis (AKC).

METHODS

Thirty-six eyes of 18 AKC patients as well as 28 eyes of 14 age- and sex-matched normal subjects were studied. The subjects underwent corneal sensitivity measurements, Schirmer test, tear film break-up time (BUT), fluorescein and Rose-Bengal staining of the ocular surface, conjunctival impression cytology and brush cytology. Impression cytology samples underwent periodic acid schiff and immunohistochemical staining with MUC16 and MUC5AC antibodies. Brush cytology specimens underwent evaluation for inflammatory cell numbers and quantitative real-time polymerase chain reaction (PCR) for MUC16 and MUC5AC mRNA expression.

RESULTS

The mean corneal sensitivity and BUT values were significantly lower in patients with AKC, compared with controls (P < 0.001). Brush cytology specimens from AKC patients revealed significantly higher numbers of inflammatory cells (P < 0.001). Specimens from patient eyes showed positive staining for MUC5AC and MUC16. MUC16 mRNA expression was significantly upregulated with significant downregulation of MUC5AC mRNA expression in eyes with AKC compared with the eyes of control subjects.

CONCLUSION

Ocular surface inflammation, decline in corneal sensitivity, tear film instability, changes in conjunctival epithelial MUC5AC and MUC16 mRNA expressions were thought to be important in the pathogenesis of atopic ocular surface disease.

Depletion of thymus-derived CD4+CD25+ T cells abrogates the suppressive effects of alpha-galactosylceramide treatment on experimental allergic conjunctivitis

BACKGROUND

We showed previously that alpha-galactosylceramide (alpha-GalCer) treatment elevated splenic CD4+CD25+Foxp3+ T-cell numbers and suppressed the development of experimental allergic conjunctivitis (EC). Here, we investigated whether CD4+CD25+Foxp3+ T cells mediate the suppressive effects of alpha-GalCer treatment on EC.

METHODS

To deplete CD4+CD25+Foxp3+ T cells, neonatal mice were thymectomized and intraperitoneally injected with anti-CD25 Ab. At 6 weeks of age, these mice were immunized with ragweed (RW) in aluminum hydroxide. Ten days later, the mice were challenged with RW in eye drops and 24 hours later, the conjunctivas and spleens were harvested for histological and flow cytometric analyses, respectively. alpha-GalCer or vehicle was injected 2 hours prior to RW challenge. In addition, alpha-GalCer was injected into thymus-intact EC-developing mice that had not been treated with anti-CD25 Ab.

RESULTS

alpha-GalCer treatment significantly suppressed EC in the thymus-intact mice that had not been treated with anti-CD25 Ab. In contrast, alpha-GalCer treatment of thymectomized and anti-CD25 Ab-treated mice did not affect the severity of EC or splenic CD4+CD25+Foxp3+ T-cell numbers. However, alpha-GalCer treatment did significantly increase splenic CD4+CD25+Foxp3+ T-cell numbers in thymectomized mice that had not received anti-CD25 Ab.

CONCLUSIONS

alpha-GalCer treatment during the effector phase of EC increased CD4+CD25+Foxp3+ T-cell numbers, which in turn suppressed the development of EC.

Contribution of alpha4beta1 integrin to the antiallergic effect of levocabastine

Levocabastine is an antiallergic drug acting as a histamine H1-receptor antagonist. In allergic conjunctivitis (AC), it may also antagonize up-regulation of the intercellular adhesion molecule-1 (ICAM-1) expressed on epithelial conjunctival cells. However, little is known about its effects on eosinophils, important effector cells in AC. The adhesion molecule integrin alpha(4)beta(1) is expressed in eosinophils; it interacts with the vascular cell adhesion molecule-1 (VCAM-1) and fibronectin (FN) in vascular endothelial cells and contributes to eosinophil activation and infiltration in AC. This study provides evidence that in a scintillation proximity assay levocabastine (IC(50) 406 microM), but not the first-generation antihistamine chlorpheniramine, displaced (125)I-FN binding to human integrin alpha(4)beta(1) and, in flow cytometry analysis, levocabastine antagonized the binding of a primary antibody to integrin alpha(4) expressed on the Jurkat cell surface. Levocabastine, but not chlorpheniramine, binds the alpha(4)beta(1) integrin and prevents eosinophil adhesion to VCAM-1, FN or human umbilical vascular endothelial cells (HUVEC) in vitro. Similarly, levocabastine affects alpha(L)beta(2)/ICAM-1-mediated adhesion of Jurkat cells. In a model of AC levocabastine eye drops reduced the clinical aspects of the late-phase reaction and the conjunctival expression of alpha(4)beta(1) integrin by reducing infiltrated eosinophils. We propose that blockade of integrin-mediated cell adhesion might be a target of the antiallergic action of levocabastine and may play a role in preventing eosinophil adhesion and infiltration in AC.

Roles of T-Cells in the Development of Allergic Conjunctival Diseases

Massive infiltration of eosinophils is the typical histopathologic feature of severe forms of allergic conjunctival diseases (ACDs) such as vernal keratoconjunctivitis. Although ACD is an antigen (Ag)-specific disease, eosinophils lack Ag-specific receptors. Therefore, my group studied the likely roles of immunocompetent cells bearing Ag-specific receptors in inducing conjunctival eosinophil infiltration in ACDs. To induce experimental conjunctivitis (EC), Brown Norway rats and C57BL/6 and Balb/c mice were passively immunized by the transfer of Ag-specific or primed IgE, splenocytes, or purified T-cells and then challenged with Ag in eyedrops. The transfer of Ag-primed splenocytes or T-cells, but not of Ag-specific IgE, induced conjunctival eosinophil infiltration. We also showed that soon after EC induction by T-cell transfer, activated Ag-specific T-cells infiltrated the conjunctiva. Moreover, when EC-developing animals were topically treated with the T-cell-specific immunosuppressants cyclosporin A and FK506, conjunctival eosinophil infiltration was abrogated. In addition, only the transfer of Ag-specific type 2 helper T-cells (TH2 cells), but not of type 1 helper T-cells or CD8 T-cells, could induce conjunctival eosinophil infiltration. Our data show that Ag-specific TH2 cells play a crucial role in inducing conjunctival eosinophil infiltration during the development of EC. It is necessary to elucidate the roles that conjunctival residential cells and immunocompetent cells other than T-cells play in the conjunctival eosinophil infiltration of EC.

Endogenous interleukin-10 produced by antigen-irrelevant cells promotes the development of experimental murine allergic conjunctivitis

Interleukin (IL)-10 is known to act as an immunoregulatory cytokine in both T helper cell 1 (Th1)- and Th2-mediated immune responses. Here, we ask whether IL-10 regulates the development of experimental allergic conjunctivitis (EC), a Th2-mediated inflammatory disease. Wild-type (WT) and IL-10 knockout (IL-10 KO) mice were immunized with ragweed (RW) and then repeatedly challenged with RW in eye drops. Twenty-four hours after the final challenge, conjunctivas were harvested for histological analysis, while the blood and spleens were used to determine the RW-specific immunoglobulin levels in serum and proliferation or cytokine responses and splenocyte transfer, respectively. The IL-10 KO mice had significantly less severe EC (as determined by conjunctival eosinophil infiltration) than the WT mice and evinced greater RW-specific splenocyte proliferation and cytokine production. However, the RW-specific immunoglobulin levels of the two strains did not differ. When the splenocytes from RW-primed WT mice were transferred into IL-10 KO or WT mice, the IL-10 KO mice showed significantly less conjunctival eosinophil infiltration. In contrast, when the splenocytes from RW-primed IL-10 KO or WT mice were transferred into WT mice, both splenocyte populations generated equivalent severe EC. These data indicate that IL-10 does not serve as an immunoregulatory cytokine in the development of EC. Instead, it appears that IL-10 produced by antigen-irrelevant cells acts in the effector phase to promote the development of EC.

[The cellular players in allergy]

Ocular allergy, with a significant increase of prevalence, is one of the most usual disease of the ocular surface. But, in a same entity, it means different kinds of clinical diseases with acute hayfever conjunctivitis, usually easy to diagnose, but also chronic perennial forms without any functional or clinical specificity among others ocular surface diseases. These clinical aspects are underlain by complex cellular mecanisms which are essentially located inside the conjunctiva. Initially, allergen cross the lacrimal tear film, the first natural barrier of the eye, then in the conjunctival epithelium, meet the antigen presenting cells, the Langerhans cells, lymphocytes and all the others components of the inflammatory and allergic reaction, including mast cells and eosinophils. The cornea could also be involved in allergic diseases, mostly in severe ones such as vernal or atopic keratoconjunctivitis, but most often, its pathology is due to direct cytotoxic effect of chemical mediators, such as eosinophil proteins, rarely results from mechanical or immunological pathways.

Antibodies to T-cell Ig and mucin domain-containing proteins (Tim)-1 and -3 suppress the induction and progression of murine allergic conjunctivitis

The T cell Ig and mucin domain-containing proteins (Tim) regulate Th1- and Th2-mediated immune responses. We investigated the ability of Abs blocking Tim-1 or Tim-3 ligand-binding activity to prevent and treat murine experimental allergic conjunctivitis (EC), a Th2-mediated disease. Treatment with either Ab during the induction phase of EC in actively immunized wild-type mice suppressed EC and upregulated Th1 and Th2 immune responses. In contrast, both Abs exacerbated EC in actively immunized IFN-gamma-knockout mice. Thus, both anti-Tim Abs suppress the pathogenic immune responses generated in the induction phase by upregulating systemic IFN-gamma production. Treatment of actively immunized mice and passively immunized mice with either anti-Tim Ab just prior to RW challenge also suppressed EC. Thus, treatment with anti-Tim-1 or anti-Tim-3 Ab can suppress both the induction and progression of EC, which could indicate potential preventive and/or therapeutic approaches for allergic diseases such as allergic conjunctivitis.

Alterations of the ocular surface epithelial mucins 1, 2, 4 and the tear functions in patients with atopic keratoconjunctivitis

BACKGROUND

An increased understanding of the ocular surface alterations at the cellular level in the conjunctiva and the cornea, may help explain the pathogenesis and the subsequent clinical appearance of atopic ocular allergies, which may be potentially blinding.

PURPOSE

To investigate MUC 1, 2 and 4 alterations, tear function and the ocular surface disorder in patients with atopic keratoconjunctivitis.

METHODS

Twenty-eight eyes of 14 atopic keratoconjunctivitis patients as well as 22 eyes of 11 age-and sex-matched normal subjects were studied. The subjects underwent corneal sensitivity measurements, Schirmer's test, tear film break-up time (BUT), fluorescein and Rose Bengal staining of the ocular surface, conjunctival impression cytology and brush cytology. Impression cytology samples underwent periodic acid-Schiff and immunohistochemical staining with MUC 1, 2 and 4 antibodies. Brush cytology specimens underwent evaluation for inflammatory cell numbers and quantitative real-time-PCR for MUC 1, 2 and 4 mRNA expression. Patient eyes with fluorescein and Rose Bengal scores greater than four points were regarded to have significant epithelial disease in this study.

RESULTS

The mean corneal sensitivity and BUT values were significantly lower in atopic patients with significant epithelial disease, compared with patients with insignificant epithelial disease and controls (P < 0.01). Brush cytology specimens from patients with significant epithelial disease revealed significantly higher numbers of inflammatory cells (P < 0.01). Specimens from patient eyes showed positive staining for MUC 1, 2 and 4. MUC 1, 2 and 4 mRNA expressions were significantly higher in eyes with significant epithelial disease compared with eyes with insignificant epithelial disease and eyes of control subjects.

CONCLUSION

Ocular surface inflammation, decline in corneal sensitivity, tear film instability, changes in conjunctival epithelial MUC 1, 2 and 4 mRNA expressions were thought to be important in the pathogenesis of atopic ocular surface disease.

Rupatadine: pharmacological profile and its use in the treatment of allergic disorders

Rupatadine is a once-daily, non-sedating, selective and long-acting new drug with a strong antagonist activity towards both histamine H(1) receptors and platelet-activating factor receptors. The use of rupatadine is indicated in adult and adolescent patients (> 12 years of age) suffering from intermittent and persistent allergic rhinitis and chronic idiopathic urticaria. In the treatment of these diseases, rupatadine is at least as effective as ebastine, cetirizine, loratadine and desloratadine. A very good safety profile of rupatadine has been evidenced in various studies, including a long-term (1-year) safety study. Rupatadine does not present drug-drug interactions with azithromycin, fluoxetine and lorazepam, but should not be administered concomitantly with known CYP3A4 inhibitors.

Role of structural cells of the cornea and conjunctiva in the pathogenesis of vernal keratoconjunctivitis

Vernal keratoconjunctivitis (VKC) is a severe type of allergic conjunctival disease characterized by the presence both of various corneal epithelial and stromal lesions as well as of conjunctival proliferative changes such as giant papillae of the upper tarsal conjunctiva and limbal lesions. These clinical findings as well as various pathophysiological characteristics of VKC are distinct from those of other types of ocular allergy and allergic diseases of other organs. The outer eye possesses specific allergological characteristics, one of which is communication between the cornea and conjunctiva through a thin layer of tear fluid. Fibroblasts of the cornea and the conjunctiva are activated by proinflammatory and T helper 2 (Th2) cell-derived cytokines. Corneal fibroblasts enhance ocular allergic reactions as a result of their activation-induced expression both of chemokines such as eotaxin and TARC as well as of adhesion molecules such as ICAM-1 and VCAM-1, all of which together promote the activation and infiltration of eosinophils and Th2 lymphocytes. In contrast, corneal epithelial cells suppress such reactions by physically separating corneal fibroblasts from bioactive substances in tear fluid. Exaggerated proliferation of and deposition of extracellular matrix by conjunctival fibroblasts likely exacerbate conjunctival inflammation. Restoration of an intact corneal epithelium and inhibition of the activities of corneal and conjunctival fibroblasts may provide a basis for the development of new treatments for severe ocular allergic diseases such as VKC.

Ocular surface and MUC5AC alterations in atopic patients with corneal shield ulcers

PURPOSE

To describe MUC5AC alterations and the ocular surface disorder in atopic patients with or without corneal ulcers.

METHODS

Atopic patients' eyes were divided into two groups according to the presence and absence of corneal ulceration. The subjects underwent corneal sensitivity measurements, Schirmer test, tear film break-up time (BUT), fluorescein and Rose Bengal staining of the ocular surface and conjunctival impression cytology and brush cytology. Impression cytology samples underwent PAS and immunohistochemical staining for MUC5AC. Brush cytology specimens underwent evaluation for inflammatory cell expression and quantitative real-time PCR for MUC5AC mRNA expression. The differences related to the tear function and ocular surface examination parameters between patients with and without corneal ulceration and healthy control subjects were studied. In addition, the differences of the study parameters related to ocular surface epithelial health and inflammatory status between patient eyes with atopic keratoconjunctivitis (AKC) and vernal keratoconjunctivitis (VKC) were investigated.

RESULTS

The mean corneal sensitivity and BUT values were significantly lower in atopic patients with corneal ulcers, compared to patients without ulcers and controls (p < 0.001). Brush cytology specimens from patients with corneal ulcers revealed significantly higher expression of inflammatory cells compared to patients without ulcers and controls (p < 0.001). Impression cytology samples from eyes with corneal ulcers showed significant squamous metaplasia and reduction in goblet cell density compared to eyes without ulcers and eyes of control subjects. The mean squamous metaplasia grade was significantly higher in eyes with AKC compared to eyes with VKC (p < 0.02). The mean goblet cell density was significantly lower in eyes with AKC compared to eyes with VKC (p < 0.01). Specimens from eyes with corneal ulcers showed PAS positive mucin pickup and did not stain positive for MUC5AC. MUC5AC mRNA expression was significantly lower in eyes with corneal ulcers compared to eyes without ulcers and eyes of control subjects. MUC5AC mRNA expression was also significantly lower in eyes with AKC compared to eyes with VKC.

CONCLUSIONS

Ocular surface inflammation, tear film instability, and decreased conjunctival MUC5AC mRNA expression were thought to be important in the pathogenesis of noninfectious corneal shield ulcers in atopic ocular surface disease.

Atopic ocular surface disease: implications on tear function and ocular surface mucins

PURPOSE

To describe tear function, mucin alterations, and ocular surface disorder in patients with atopic diseases.

METHODS

Subjects underwent corneal sensitivity measurements, Schirmer test, tear film break-up time (BUT) assay, and fluorescein and rose Bengal staining of the ocular surface. Conjunctival impression cytology and brush cytology were also conducted. Impression cytology samples underwent PAS and immunohistochemical staining for MUC5AC. Brush cytology specimens underwent evaluation for inflammatory cell expression and RT-PCR for MUC5AC mRNA expression. Differences related to tear function and ocular surface examination parameters among patients with and without corneal ulceration and healthy control subjects were studied.

RESULTS

Mean corneal sensitivity and BUT values were significantly lower in atopic patients with corneal ulcers compared with patients without ulcers and controls (P<0.001). Brush cytology specimens from patients with corneal ulcers revealed significantly higher expression of inflammatory cells compared with patients without ulcers and controls (P<0.001). Impression cytology samples from eyes with corneal ulcers showed significant squamous metaplasia and reduction of goblet cell density compared with eyes without ulcers and control subjects. Specimens from eyes with corneal ulcers showed PAS (+) mucin pick up and did not stain positive for MUC5AC. MUC5AC mRNA expression was significantly lower in eyes with corneal ulcers compared with in eyes without ulcers and control subjects.

CONCLUSIONS

Ocular surface inflammation, tear film instability, and decreased conjunctival MUC5AC mRNA expression are important in the pathogenesis of noninfectious corneal shield ulcers in atopic ocular surface disease.

Objective measurement of allergic reactions in the eye

PURPOSE OF REVIEW

Conjunctival allergen challenge has become a useful model of human ocular allergy and an accepted method for studying the effects of topical antiinflammatory medications. Conjunctival allergen challenge reactions are typically evaluated in a subjective fashion. Erythema and edema are graded by observation, using a 0 to 4 scale. Itching is graded on a 0 to 4 scale by questioning the subject. We have reviewed the recent literature on conjunctival allergen challenge, including recently developed methods aimed at objective assessment of ocular allergic reactions, such as the erythema, edema, sensation, or EES, method.

RECENT FINDINGS

Conjunctival erythema can be measured objectively using a spectroradiometer, or colorimeter, a device which measures the chromaticity of reflected light, and provides the x, or u', and y, or v', coordinates of any color. Edema of the eyelids and conjunctiva can be measured using a fractional millimeter reticule in the eyepiece of a slit lamp microscope. Ocular surface sensation can be evaluated using the aesthesiometer of Cochet and Bonnet, or by using a 'sensation index', a measurement that takes into account the intensity and duration of itching.

SUMMARY

CAC reactions can be measured objectively using the erythema, edema, sensation method, as well as subjectively by observation and questioning.

Eotaxin-1 (CCL11) up-regulation in tears during seasonal allergic conjunctivitis

PURPOSE

To compare in-season eotaxin-1 levels in tears of patients suffering from seasonal allergic conjunctivitis (SAC) with (1) tears of normal subjects and (2) tears of SAC patients out of season.

METHODS

Tears of 11 SAC patients and six control volunteers were collected during the pollen season. Tears of five SAC patients showing a strong sensitivity to grass pollen (skin-prick tests and specific serum IgE) were collected both in season and out of season. ELISA measured eotaxin-1 level.

RESULTS

Eotaxin-1 concentration in tears of SAC patients [2,100+/-503 (SEM) pg/ml] and normal subjects (1,193+/-176 pg/ml) were significantly different (P=0.0049). Regarding allergic patients, the clinical score (sum of five allergic criteria) was significantly different in season and out of season (P=0.0043) as was also the case with eotaxin-1 concentration (P=0.024).

CONCLUSIONS

The eotaxin-1 concentration in tears of patients showing hay fever could confirm a diagnosis of seasonal ocular allergy.

The promotion of eosinophil degranulation and adhesion to conjunctival epithelial cells by IgE-activated conjunctival mast cells

BACKGROUND

Allergen-mediated mast cell activation is a key feature of ocular allergic diseases. Evidence of eosinophil-derived mediators in tears and conjunctival biopsy specimens has been associated with chronic ocular allergic inflammation.

OBJECTIVE

To examine the role of conjunctival mast cell mediators in eosinophil adhesion to conjunctival epithelial cells and eosinophil degranulation.

METHODS

Conjunctival cells were obtained by enzymatic digestion of cadaveric conjunctival tissues. Eosinophils were obtained from peripheral blood samples using negative magnetic bead selection. The effect of IgE-activated mast cell supernates on eosinophil degranulation and adherence to epithelial cells was compared with supernates obtained from mast cells pretreated with a degranulation inhibitor (olopatadine). Eosinophil adhesion was measured by eosinophil peroxidase assay, and eosinophil degranulation was measured by eosinophil-derived neurotoxin radioimmunoassay.

RESULTS

IgE-activated conjunctival mast cell supernates stimulated adhesion of eosinophils to epithelial cells (20.4% +/- 6.3% vs 3.1% +/- 1.0%; P = .048). Degranulation was not required for this process (no effect of olopatadine). IgE-activated mast cell supernates stimulated eosinophil-derived neurotoxin release (108.89 +/- 8.27 ng/10(6) cells vs 79.45 +/- 5.21 ng/10(6) cells for controls, P = .02), which was significantly inhibited by pretreatment of mast cells with a degranulation inhibitor (79.22 +/- 4.33 ng/10(6) cells vs 61.09 +/- 5.39 ng/10(6) cells for olopatadine pretreated and untreated, respectively, P = .02).

CONCLUSIONS

Mediators released from conjunctival mast cells promote eosinophil adhesion to conjunctival epithelial cells and eosinophil degranulation. Degranulation inhibition studies suggest that different mast cell mediators are involved in regulation of these events.

Inhibitory effects of ketotifen on eotaxin-dependent activation of eosinophils: consequences for allergic eye diseases

BACKGROUND

The aim of this study was to investigate the effects of ketotifen on different parameters of human eosinophil functions, namely chemotaxis, oxidative metabolism and mediator release, induced after activation.

METHODS

Eosinophils from hypereosinophilic patients or normal donors were purified by Percoll gradient and the magnetic cell separation system. Chemotaxis was studied using the Boyden chamber technique using three potent chemoattractants: formyl-methionine-leucine-phenylalanine (fMLP), interleukin (IL)-5 and eotaxin. Oxidative metabolism was determined by a luminol-dependent chemiluminescence assay after activation with eotaxin or secretory immunoglobulin A (sIgA). The release of eosinophil cationic protein (ECP) and eosinophil derived neurotoxin (EDN) was measured by radioimmunoassay after activation with sIgA.

RESULTS

At pharmacologically active concentrations and in a dose-dependent manner, ketotifen significantly inhibited the chemotaxis of eosinophils to fMLP, IL-5 and eotaxin. The production of reactive oxygen species induced by eotaxin and sIgA was decreased by ketotifen, showing a more pronounced effect when cells were activated by eotaxin. Activation by sIgA resulted in ECP and EDN release, which was partially inhibited by ketotifen.

CONCLUSIONS

Through inhibition of chemotaxis, ketotifen might limit the number of eosinophils at the inflammation site during allergic reaction. Furthermore, inhibition by ketotifen of main inflammatory mediators release suggests a potential role of the drug in limiting the pathological potential of eosinophils.

Toxic eosinophil granule protein deposition in corneal ulcerations and scars associated with atopic keratoconjunctivitis

PURPOSE

Recurrent or persistent corneal erosions and ulcerations are typical complications of atopic keratoconjunctivitis. Toxic eosinophil granule proteins such as major basic protein (MBP) and eosinophil cationic protein (ECP) may be involved in this pathogenetic process. This study was designed to demonstrate the presence of toxic eosinophil granule proteins in corneal tissue from a patient with corneal complications of atopic keratoconjunctivitis.

DESIGN

Observational case report.

METHODS

Three corneal buttons of a patient with atopic keratoconjunctivitis associated ulcerations or scarring were examined by light microscopy and by immunofluorescence technique.

RESULTS

A linear deposition of eosinophil granular substance was detected subepithelially above Bowman's membrane in all corneal buttons. Indirect immunofluorescence identified this material as MBP and ECP. The deposits were not limited to the area of ulceration, but were also found underneath intact corneal epithelium. Multiple eosinophils were present in the upper corneal stroma. Normal corneas and negative control sections of the pathologic buttons revealed only minimal nonspecific staining at the surface of the epithelium.

CONCLUSIONS

Both MBP and ECP are known to affect human corneal epithelial cell viability and morphology in vitro. Moreover, MBP was shown to inhibit epithelial migration and protein synthesis. These toxic eosinophil proteins may also be responsible for corneal instability, recurrent and persistent corneal epithelial defects and ulcerations in patients with atopic keratoconjunctivitis.

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.

Pathophysiology of ocular allergy: the roles of conjunctival mast cells and epithelial cells

Allergic eye disease is associated with IgE-mediated conjunctival inflammation leading to signs of immediate hypersensitivity, including redness, itching, and tearing. Pathologic studies using conjunctival mast cells demonstrate that these cells, when sensitized with IgE antibody and exposed to environmental allergens, release mediators involved with allergic inflammation. The type, release kinetics, and concentration of these mediators in the conjunctiva have not been completely characterized. The ability to isolate and purify mast cells and epithelial cells from human conjunctival tissue has permitted the study of mediator release and cell-to-cell signaling in this tissue. Our laboratory has developed in vitro and in vivo models to better understand how inflammatory cells are recruited to and infiltrate conjunctival tissues. These models demonstrate that mast-cell activation may supply sufficient cytokine signaling to initiate and direct the well-orchestrated trafficking of eosinophils to the ocular surface, facilitate their adhesion, and cause release of potent mediators of ocular inflammation.

The pathogenesis of allergic conjunctivitis

The clinical presentation of the various forms of allergic conjunctivitis varies greatly from mild symptoms to severe disease with vision-threatening complications. Although an IgE-mediated type-1 hypersensitivity reaction has been demonstrated or postulated in many types of allergic eye disease, the pathophysiology underlying the allergic conjunctivitides is not fully understood. The variety of currently available treatment options underscores the complexity of the chemical reactions associated with mast cell degranulation and mediator release causing the onset of allergic signs and symptoms. Many of these treatments are merely palliative and do not eliminate the complex immune response initiating the symptoms, so there is a recurrence of disease as soon as the therapy is discontinued. Models of allergic eye disease have significantly aided the discovery of new anti-allergic and anti-inflammatory compounds that can be used safely in the eye.

Increase in CD45RO+ cells and activated eosinophils in chronic allergic conjunctivitis

We assessed the infiltration of CD45RO+ cells in conjunctival biopsies of fifteen subjects affected by seasonal allergic conjunctivitis by means of immunohistochemistry. Correlations between infiltration of CD45RO+ cells and serum and mucosal indices of eosinophilic activation were investigated. The study was performed in autumn and all selected patients showed <<red eyes>> also in absence of sensitising pollens. Fifteen healthy subjects were used as controls. The semi-quantitative count of CD45RO+ cells in biopsy specimens demonstrated that positive cells were higher in allergic patients than in controls (p < 0.001) and EG2+ eosinophils were present only in biopsies of allergic patients. Furthermore, a statistically significant positive correlation (r = 0.73; p < 0.001) between CD45RO+ lymphocytes and EG2 positive eosinophils, was observed in the biopsies of allergic patients. Total serum IgE significantly correlated with CD45RO+ cells (r = 0.61; p < 0.02) and EG2+ eosinophils (r = 0.67; p < 0.01) in the conjunctiva. On the other hand serum ECP did not correlate with any histological and immunohistochemical parameters in the conjunctival biopsies. The present study shows that mild symptoms in SCA patients out of pollen season are associated with inflammation of the conjunctiva as shown by an increased number of CD45RO and EG2 positive cells.