Ultrastructural anatomy of CALT follicles in the rabbit reveals characteristics of M-cells, germinal centres and high endothelial venules

Conjunctiva-associated lymphoid tissue (CALT) is a part of the eye-associated lymphoid tissue (EALT) at the ocular surface. Its lymphoid follicles are usually characterized by using light microscopy, but its ultrastructure remains largely unknown. In this study, flat whole-mount conjunctival tissues (n = 42) from 21 young adult rabbits were investigated native in reflected light, and further stained and cleared (n = 6), in paraffin histology sections (n = 6), scanning electron microscopy (SEM, n = 4) and transmission electron microscopy (TEM, n = 4). Secondary lymphoid follicles accumulated into a dense group nasally towards the lacrimal punctum of the lower lid. High endothelial venules (HEV) with typical ultrastructure occurred in the parafollicular zone. The bright germinal centre (GC) contained lymphoblasts, follicular dendritic cells, apoptotic cells and tingible body macrophages. The follicle-associated epithelium (FAE) was devoid of goblet cells and contained groups of lymphoid cells. TEM showed these cells to be located in cytoplasmic pockets of superficial electron-lucent cells with a thin cytoplasmic luminal lining that contained a fine filament meshwork and numerous endocytotic vesicles. These M-cells were sitting between and on top of the ordinary dense epithelial cells that were located basally and formed pillar-like structures. In stereoscopic SEM, the surface cells were very large, had a polygonal outline and covered cavernous spaces. The rabbit has a CALT with typical follicular morphology, including HEV for regulated lymphocyte migration and epithelial cells with ultrastructural characteristics of M-cells that allow antigen transport as indicated by the GC-reaction. The arrangement of these M-cells on top of and between epithelial pillar cells may reflect a special structural requirement of the multilayered CALT FAE.

Pathological keratinisation in the conjunctival epithelium of Sjögren's syndrome

Our previous gene expression analysis suggested that conjunctival epithelial cells of Sjögren's syndrome (SS) are inclined to hyper-proliferation and keratinisation status. The goal of this study is to elucidate whether such pathological situations really exist in the conjunctival epithelium of SS. Also, involvement of inflammatory cytokines in this disease was investigated. Conjunctival tissues or cells obtained from 12 SS patients and 13 normal subjects were subjected to indirect immunostaining to analyse expression of transglutaminase 1 (TGase1), involucrin, keratins 1, 4, 10 and 13. The number of proliferative cells was also analysed by immunostaining of Ki67 antigen. Additionally, changes in gene expression of TGase1 and involucrin after stimulation by IL-1 or IFN-gamma were quantified by real-time RT-PCR. TGase1 and involucrin were up-regulated in the conjunctival epithelium of SS patients. Although not statistically significant, Ki67 positive proliferative cells were slightly increased in SS patients. IFN-gamma stimulation significantly up-regulated TGase1 and unexpectedly repressed involucrin gene expression. IL-1 did not render any significant changes in the expression of these genes. These results suggest the existence of pathological keratinisation in the conjunctival epithelium of SS and also support our hypothesis that inflammatory cytokines may be involved in the ocular surface pathological changes in SS.

[Conjunctival blistering associated with pemphigus vulgaris: report of a case]

CLINICAL CASE

A patient with a conjunctival blister was diagnosed with pemphigus vulgaris by immunofluorescence tests performed on a conjunctival biopsy.

DISCUSSION

Pemphigus vulgaris is an uncommon but serious autoimmune disease that produces blisters of the skin and mucous membranes. Ocular findings are rare, but include conjunctivitis and marginal eyelid erosions. Conjunctival blisters and erosions related to this condition have not been previously reported in the literature. This diagnosis can be made through direct immunofluorescence tests performed on biopsy samples of affected tissue. Unless the condition is properly diagnosed and treated, it has a high mortality.

Cellular inflammatory response induced by sensory denervation of the conjunctiva in monkeys

The inflammatory response induced by sensory denervation of the cornea, neuroparalytic (neurotrophic) keratitis, has been widely reported in the literature. Clinical evidence has shown that the conjunctiva also responds to sensory denervation, but little is known of the cytology of the conjunctival tissue response to denervation. The purpose of this study therefore was to investigate the cytological aspects of tissue response induced in the conjunctiva of monkeys by sensory denervation. Intracranial ophthalmic neurotomy was carried out in three monkeys, maxillary neurotomy in four, combined ophthalmic and maxillary neurotomy in two, and infraorbital nerve transaction in one monkey. These various operations were performed for other experimental purposes, but the conjunctival tissues from the animals were suitable and available to study the cytology of the inflammatory response induced in the tissue following the sensory denervation. The cytological changes were studied using light microscopy. Complete or severe ophthalmic nerve transection induced significant inflammatory responses, which were largely confined to the tarsal region of the conjunctiva. The responses included a substantial increase in the infiltration of the epithelium by polymorphonuclear leucocytes and severe disruption of the epithelium. The number of macrophages in the conjunctiva also increased. The response induced by maxillary denervation, however, was not as pronounced as that induced by sensory denervation. The restriction of the conjunctival tissue response to the tarsal region was considered to be due to the friction between the tarsal conjunctiva (and the hard tarsal plate) and the cornea during blinking. This study shows that sensory denervation of the conjunctiva elicits an inflammatory response characterized by substantial infiltration of the epithelium by neutrophil and macrophage and disorganization of the conjunctival tissue.

The role of eye-associated lymphoid tissue in corneal immune protection

Because the cornea is optimized for refraction, it relies on supporting tissues for moistening and nutrition and in particular for immune protection. Its main support tissue is the conjunctiva, in addition to the lacrimal gland, the latter which provides soluble mediators via the tear film. The cornea and conjunctiva constitute a moist mucosal surface and there is increasing evidence that apart from innate defence mechanisms, also lymphoid cells contribute to the normal homeostasis of the corneal surface. A Medline-based literature search was performed in order to review the existing literature on the existence, composition and functions of mucosa-associated lymphoid tissue (MALT) at the ocular surface for corneal protection. The existence of lymphoid cells at the ocular surface and appendage has been known for many years, but for a long time they were believed erroneously to be inflammatory cells. More recent research has shown that in addition to the known presence of lymphoid cells in the lacrimal gland, they also form MALT in the conjunctiva as conjunctiva-associated lymphoid tissue (CALT) and in the lacrimal drainage system as lacrimal drainage-associated lymphoid tissue (LDALT). Together this constitutes an eye-associated lymphoid tissue (EALT), which is a new component of the mucosal immune system of the body. When the topographical distribution of CALT is projected onto the ocular surface, it overlies the cornea during eye closure and is hence in a suitable position to assist the corneal immune protection during blinking and overnight. It can detect corneal antigens and prime respective effector cells, or distribute protective factors as secretory IgA.

Toll-like receptor 2 expression on human conjunctival epithelial cells: a pathway for Staphylococcus aureus involvement in chronic ocular proinflammatory responses

BACKGROUND

Staphylococcus aureus colonization is common in atopic keratoconjunctivitis, potentially activating epithelial cells via toll-like receptor 2 (TLR-2) and the receptor for platelet-activating factor (PAFR).

OBJECTIVES

To examine human conjunctival epithelial cells for the expression of TLR-2 in vitro and in vivo and to evaluate the role of TLR-2 in S aureus-mediated activation of these cells.

METHODS

Conjunctival epithelial cells isolated from cadaveric tissues were stimulated with interferon gamma (IFN-gamma) or a commercial S aureus cell wall extract (Staphylococcus aureus-CWE) (with or without anti-TLR-2 blocking antibody or PAFR antagonist) and were analyzed for tumor necrosis factor alpha (TNF-alpha) and interleukin 8 (IL-8) release; surface expression of TLR-2, intercellular adhesion molecule-1, HLA, and CD14; and TLR-2 messenger RNA expression. Ocular surface cells collected via impression cytology were examined for TLR-2 expression via flow cytometry.

RESULTS

Expression of TLR-2 was up-regulated on conjunctival epithelial cells by IFN-gamma and Staphylococcus aureus-CWE. Expression of TLR-2 messenger RNA was increased by IFN-gamma. Staphylococcus aureus-CWE up-regulated intercellular adhesion molecule 1, HLA, and CD14 expression and increased TNF-alpha and IL-8 release in a dose-dependent manner. Anti-TLR-2 significantly inhibited TNF-alpha release, whereas PAFR antagonist significantly inhibited IL-8 release. Toll-like receptor 2 was expressed on conjunctival epithelial cells from 4 of 5 patients with atopic keratoconjunctivitis, 3 of 5 with seasonal allergies, and 0 of 3 without allergies.

CONCLUSIONS

Conjunctival epithelial cells express TLR-2 and may play an active role in the chronic ocular inflammatory response to S aureus through pathways that involve TLR-2 and PAFR.

Conjunctival M cells selectively bind and translocate Maackia amurensis leukoagglutinin

Antigen-sampling M cells are found in the follicle-associated epithelium above organized lymphoid tissue in many mucosae. They play a key role in initiating the mucosal immune response and act as a site of entry for opportunistic pathogens. This study investigates the presence of M cells in the Guinea pig conjunctiva. Maackia amurensis leukoagglutinin I and II (MAL-I and MAL-II) were identified as potential conjunctival M cell markers based on a screening of 12 lectins and 5 carbohydrate epitope antibodies on aldehyde-fixed follicles. Biotinylated or fluorescein-conjugated MAL-I was then instilled into conjunctival sacs in vivo for 15-60 min. Specimens were assessed by epi-fluorescence stereomicroscopy, confocal scanning laser microscopy and transmission and scanning electron microscopy (TEM and SEM). Selective labelling of a subset of epithelial cells overlying lymphoid follicles was observed following in vivo exposure to MAL-I. MAL-I labelling was restricted to cells with sparse, irregular microvilli. Cells preferentially labelled with MAL-I were found to internalize the lectin during a 60 min in vivo exposure. MAL-I was transcytosed to basolateral membranes of cells filled with intracellular vesicles during a 45 min in vivo incubation. This study demonstrates that the Guinea pig conjunctiva contains a cell with morphological and functional characteristics of antigen-sampling M cells.

Case-controlled clinical and histopathological study of conjunctivochalasis

BACKGROUND/AIMS

Conjunctivochalasis, a secondary cause of the watery eye, is frequently seen in the older age group as an elevation of the bulbar conjunctiva lying along the lateral or central lower lid margin. A prospective, interventional, case-controlled clinical and histopathological study was conducted. The relevant features of 18 patients (29 eyes) who had their conjunctivochalasis resected as part of the surgical management of their watery eye syndrome were examined. In the control group, tissue was obtained from an age matched series of 24 normal subjects undergoing routine cataract surgery.

METHODS

24 controls (24 specimens) and 18 patients (29 specimens) had conjunctival strip biopsies, taken from the usual lid margin level bulbar conjunctiva in line with the inferior limbus (controls), and the clinically apparent conjunctivochalasis (patients). These were submitted for histological study.

RESULTS

23 of 24 control sections demonstrated normal conjunctival variation. Four of 29 patient specimens demonstrated a chronic non-granulomatous conjunctivitis, while three eyes of the patient group (two patients) demonstrated features of elastosis. Of the four patients who had the inflammatory infiltrates, three had functional nasolacrimal duct obstructions (FNLDOs) and one had a primary acquired nasolacrimal duct obstruction (PANDO). Of the two patients who had elastosis, one had an FNLDO and the other had normal lacrimal drainage and was Jones 1 positive.

CONCLUSION

Six of 18 patients--that is, seven of 29 specimens of conjunctivochalasis demonstrated signs of elastosis or of chronic non-granulomatous inflammation. Clinically, patients had a spectrum of aetiologies of their watery eye syndrome.

Selective uptake of iron oxide by rabbit conjunctival lymphoid follicles

PURPOSE

To determine whether conjunctival lymphoid follicles are preferential sites for uptake of foreign material in the preocular tear film.

METHODS

Iron oxide suspension was applied to the eyes of New Zealand white rabbits for selected times, and the conjunctiva was examined histochemically for the presence of iron.

RESULTS

Iron was observed by histochemical staining within conjunctival follicle-associated epithelium at 1 hour and deep within the follicles at 4 hours after exposure. Iron was not seen within nonfollicular conjunctival epithelium or underlying substantia propria at any time after iron oxide application.

CONCLUSIONS

Iron oxide in the preocular tear film is taken up preferentially by conjunctival lymphoid tissue, supporting the hypothesis that mammalian conjunctival lymphoid follicles may participate in the acquired immune response to pathogens in the preocular tear film.

Macrophage inflammatory protein-1alpha as a costimulatory signal for mast cell-mediated immediate hypersensitivity reactions

Regulation of the immune response requires the cooperation of multiple signals in the activation of effector cells. For example, T cells require signals emanating from both the TCR for antigen (upon recognition of MHC/antigenic peptide) and receptors for costimulatory molecules (e.g., CD80 and CD60) for full activation. Here we show that IgE-mediated reactions in the conjunctiva also require multiple signals. Immediate hypersensitivity reactions in the conjunctiva were inhibited in mice deficient in macrophage inflammatory protein-1alpha (MIP-1alpha) despite normal numbers of tissue mast cells and no decrease in the levels of allergen-specific IgE. Treatment of sensitized animals with neutralizing antibodies with specificity for MIP-1alpha also inhibited hypersensitivity in the conjunctiva. In both cases (MIP-1alpha deficiency and antibody treatment), the degranulation of mast cells in situ was affected. In vitro sensitization assays showed that MIP-1alpha is indeed required for optimal mast cell degranulation, along with cross-linking of the high-affinity IgE receptor, FcepsilonRI. The data indicate that MIP-1alpha constitutes an important second signal for mast cell degranulation in the conjunctiva in vivo and consequently for acute-phase disease. Antagonizing the interaction of MIP-1alpha with its receptor CC chemokine receptor 1 (CCR1) or signal transduction from CCR1 may therefore prove to be effective as an antiinflammatory therapy on the ocular surface.

Comparaison de trois collyres anti-allergiques lors d’un test de provocation conjonctivale spécifique : méquitazine, lévocabastine et dexaméthasone

PURPOSE

In order to assess the efficacy of an antihistaminic eye drop containing 0.05% mequitazine in the prevention of allergy induced by a conjunctival provocation test, a double-masked, randomized, intraindividual study compared this eye drop to 0.05% levocabastine and 0.1% dexamethasone eye drops in 24 subjects allergic to grass pollen.

METHOD

During the first phase of treatment, randomized subjects received one drop of dexamethasone in one eye and one drop of either mequitazine or levocabastine in the fellow eye. During the second phase of treatment, they were given one drop of dexamethasone in the same eye as previously, and one drop of the treatment that had not been given during the first phase (levocabastine or mequitazine) in the fellow eye. Fifteen minutes after each instillation phase, a conjunctival provocation test was performed. Hyperemia, itching, tearing, chemosis and palpebral edema were the five signs or symptoms taken into account to assess the treatment efficacy. Their intensity was evaluated 3, 5 and 10 min after the conjunctival provocation test. The primary efficacy criterion was the global score obtained by measuring hyperemia and itching intensity.

RESULTS

The score was reduced significantly more (p < 0.0001) for the eyes treated with mequitazine or levocabastine than for those treated with dexamethasone at all evaluation times. The difference was also significant for hyperemia (p < 0.001), itching (p < 0.001), and tearing (p < 0.05). The tolerability of the three eyedrops was satisfactory.

CONCLUSION

Mequitazine and levocabastine were safe and significantly more effective than dexamethasone in preventing the allergic response induced by a conjunctival provocation test when they were instilled 15 min before contact with the allergen.

Observation of lymphatic vessels in orbital fat of patients with inflammatory conditions: a form fruste of lymphangiogenesis?

In the absence of antibodies specific for lymphatic vessels, analysis of lymphatic vessels within different tissues has been widely performed with light microscopic and, most importantly, electron microscopic techniques. In regard to lymphatic vessels in the ocular globe and the periocular structures, controversy remains about the specific distribution of lymphatic channels. It is postulated that bulbar and retrobulbar tissues are devoid of lymphatic vessels, but lymphatic vessels have been demonstrated in lacrimal gland and epibulbar conjunctiva. In this study, we analyzed orbital fat for the presence of lymphatic tissue using D2-40, a monoclonal antibody, specific for lymphatic vessels. We found lymphatic vessels present within bulbar conjunctiva extending to the level of the ciliary apparatus. No lymphatics were identified in healthy anterior orbital adipose tissue. In two cases of orbital mucor-mycosis and one case of panendophthalmitis, significant lymphovascular proliferation was present within granulation tissue associated with the acute inflammation. We conclude that lymph vessel proliferation may be induced in inflammatory conditions in tissues which are normally devoid of lymph channels.

Correlation between conjunctival provocation test results and conjunctival symptoms in pollinosis - preliminary report

The aim of the study was to investigate the correlation between the level of reactivity in conjunctival provocation test and conjunctival symptoms that develop during the pollination season in grass allergic patients. Conjunctival provocation test with grass pollen allergens was performed in 22 patients suffering from pollinosis. During grass pollination season all patients monitored their symptoms with Symptoms Score Cards. A parallel measurement of the level of grass pollen count was carried out on a daily basis by volumetric method. The mean grass pollen count which triggered the reaction in individual patients depended on the results of conjunctival provocation test. The lowest pollen count level was observed in cases of patients with positive conjunctival provocation test at low allergen extract concentration of 160 and 500 BU/ml, whereas the highest count in cases of 1,600 BU/ml. The difference between the results was found to be statistically significant. A threshold grass pollen concentration for conjunctival symptoms was established at the level of 22 grains/m (3). We conclude that the patients with pollinosis and high reactivity in conjunctival provocation test develop conjunctival symptoms earlier during grass pollination season than the patients who are characterised by lower reactivity during conjunctival provocation test.

Provocation testing with recombinant allergens

In the past few decades, DNA technology has enabled the production of defined recombinant allergen molecules for diagnostic and therapeutic purposes. Recombinant allergens containing most of the relevant IgE epitopes present in natural allergen sources are now available and allergen proteins can be produced that are identical, without biological or batch-to-batch variation. A great advantage of recombinant allergens is that they can be used for component-resolved diagnostics, which makes it possible to establish the patient's individual IgE reactivity profile before therapy is selected. However, before recombinant allergens can be applied in clinical practice their biological activity has to be carefully investigated in vivo. We here describe the most commonly used provocation methods (skin tests (prick and intradermal), nasal, bronchial, and conjunctival provocations) and how they can be performed. We also discuss the results so far obtained with in vivo testing using recombinant allergens and envisage their future use for immunotherapy.

ICAM-1 expression predisposes ocular tissues to immune-based inflammation in dry eye patients and Sjögrens syndrome-like MRL/lpr mice

PURPOSE

We previously reported that immune-based inflammation occurs on the ocular surface of humans as well as canines with keratoconjunctivitis sicca (KCS). Intercellular adhesion molecule-1 (ICAM-1) was found to be upregulated on lymphocytes and/or vascular endothelial cells resulting in lymphocytic diapedesis to the lacrimal and conjunctival tissues. The purpose of the current study was to demonstrate the role of ICAM-1 in (1) resident epithelial cell response during ocular inflammation, (2) local and/or peripheral lymphocyte activation or accumulation in the ocular tissues, and (3) whether anti-ICAM-1 is effective to attenuate immune-mediated ocular inflammation.

METHODS

ICAM-1 levels in various ocular tissues of human with KCS and/or MRL/lpr mouse were evaluated by immunohistochemistry and in situ hybridization for protein and messenger RNA (mRNA) expression, respectively. Soluble ICAM-1 concentrations in MRL/lpr mouse plasma over the course of disease development were measured by ELISA. Cell proliferation within ocular tissues was assessed by bromodeoxyuridine (BrdU) incorporation and immunohistochemical detection. The level of T cell activation was determined by IL-2 receptor (CD25, a marker of T cell activation and proliferation) and CD69 (a marker of T cell activation) immunoreactivity using FACS analysis. To examine the effectiveness of anti-ICAM-1/LFA-1 in elimination of lacrimal gland inflammation, MRL/lpr mice were injected intraperitoneally (i.p.) with or without monoclonal antibodies against ICAM-1 and LFA-1 at three or eight weeks of age.

RESULTS

Increased endogenous ICAM-1 expression at the level of protein and mRNA was detected in the epithelial cells present in the conjunctival and accessory lacrimal tissues in dry eye patients. In MRL/lpr mice, ICAM-1 expression by lacrimal acinar epithelial cells and conjunctival epithelial cells were detected in addition to inflammatory infiltrates and vascular endothelial cells at 16 weeks of age. Soluble ICAM-1 levels were markedly increased concomitantly with disease progression over time as compared with the controls. No significant lymphocytic proliferation (a lack of BrdU and CD25 immunoreactivities) was detected within lacrimal glands of MRL/lpr mice at the disease onset. However, a population of the infiltrated T cells were CD69 positive, indicating the activation stage of a T cell subset. Treatment using monoclonal antibodies against murine ICAM-1 and LFA-1 resulted in a decrease in the number of inflammatory infiltrates in MRL/lpr mice.

CONCLUSIONS

Our findings suggest that ICAM-1 upregulation locally and systemically promote lymphocyte activation and migration to the ocular surface (OS). Ocular resident epithelium is an active component of ocular surface and is capable of interacting with invasive lymphocytes by ICAM-1 production in response to immune activation and inflammation. ICAM-1 synthesized by epithelial cells may serve as a signaling molecule for predisposition of ocular surface inflammation and facilitate potential antigen presentation by epithelial cells. Lymphocytic infiltrates in the lacrimal gland of the MRL/lpr mouse appeared to be the result of the accumulation, but not proliferation of circulating lymphocytes diapodesed from the vasculature that had migrated into the local ocular tissues. The potential use of anti-ICAM-1 therapy in treating immune-based inflammatory diseases such as dry eye deserves further investigation.

No apparent association between periocular and ocular microcolonization and the degree of inflammation in patients with atopic keratoconjunctivitis

BACKGROUND

The cause of the chronic inflammation in atopic keratoconjunctivitis (AKC), the ocular manifestation of atopic eczema/dermatitis syndrome, is largely unknown.

OBJECTIVE

To investigate the possibility that microorganisms may be important in the inflammatory activity in AKC.

METHODS

Fifteen patients with AKC participated in the study. The presence of aerobic bacteria and fungi was related to the severity of clinical signs, the numbers of inflammatory cells in tears and conjunctival biopsies, and the concentration of various cytokines in tears. In addition, serological evidence for IgE sensitization to Staphylococcus aureus B antigen and Malassezia sympodialis antigen was investigated. Twelve healthy subjects were included for control purposes.

RESULTS

The patients exhibited moderate clinical signs of AKC. No relation was found between the severity of AKC and the presence of microorganisms, despite the fact that S. aureus was frequently isolated. AKC patients showed significantly higher levels of IFN-gamma, TNF-alpha (tumour necrosis factor-alpha), IL-2, IL-4, IL-5 and IL-10 than controls. An association was found between conjunctival signs and the levels of all cytokines except IL-5.

CONCLUSION

We found no evidence to suggest that periocular and ocular microcolonization are related to inflammatory parameters in AKC. However, confirmation of the present results in a longitudinal study with repeated clinical examinations and samplings in the same individual is required before the contribution of S. aureus to on-going inflammation in AKC can be dismissed.

[Eye-associated lymphoid tissue (EALT) is continuously spread throughout the ocular surface from the lacrimal gland to the lacrimal drainage system]

INTRODUCTION

Components of the mucosal immune system (MALT) have been identified in the conjunctiva (as CALT) and the lacrimal drainage system (as LDALT). Their structural and functional relation with the established immune protection by the lacrimal gland is unclear.

MATERIAL AND METHODS

Macroscopically normal and complete tissues of the conjunctiva, lacrimal drainage system and lacrimal gland from human body donors were investigated by analysis of translucent whole mounts, and using histology, immunohistology as well as scanning and transmission electron microscopy.

RESULTS

A typical diffuse lymphoid tissue, composed of effector cells of the immune system (T-lymphocytes and IgA producing plasma cells) under an epithelium that contains the IgA transporter SC, is not isolated in the conjunctiva and lacrimal drainage system. It is anatomically continuous from the lacrimal gland along its excretory ducts into the conjunctiva and from there via the lacrimal canaliculi into the lacrimal drainage system. Lymphoid follicles occur in a majority (about 60%) and with bilateral symmetry. The topography of CALT corresponds to the position of the cornea in the closed eye.

CONCLUSION

These results show that the MALT of the lacrimal gland, conjunctiva and lacrimal drainage system constitute an anatomical and functional unit for immune protection of the ocular surface. Therefore it should be integrated as an "eye-associated lymphoid tissue" (EALT) into the MALT system of the body. EALT can detect ocular surface antigens by the lymphoid follicles and can supply other organs and the ocular surface including the lacrimal gland with specific effector cells via the regulated recirculation of lymphoid cells.

T lymphocyte mediated lysis of mitomycin C treated Tenon's capsule fibroblasts

AIMS

To evaluate the effect of T cell co-culture on mitomycin C treated and untreated Tenon's capsule fibroblasts.

METHODS

IL-2 dependent allogeneic T cells were incubated over a monolayer of mitomycin C treated or control fibroblasts. Fibroblast numbers were evaluated by direct counts using phase contrast microscopy. To determine whether T cell mediated lysis was a consequence of MHC mismatch, co-culture experiments were repeated with autologous T cells. The effect of Fas receptor blockade was established by co-incubation with a Fas blocking (M3) antibody.

RESULTS

T cell co-culture resulted in a dramatic reduction in fibroblast survival compared to mitomycin C treatment alone (p = 0.032). T cell killing required fibroblast/lymphocyte cell to cell contact and was observed in both allogeneic and autologous co-culture experiments. Fas blocking antibodies did not significantly inhibit T cell killing (p = 0.39).

CONCLUSION

T cells augment mitomycin C treated fibroblast death in vitro. Similar mechanisms may contribute to the cytotoxic effect of mitomycin C in vivo and account for the largely hypocellular drainage blebs that are observed clinically.

Ocular surface epithelium induces expression of human mucosal lymphocyte antigen (HML-1) on peripheral blood lymphocytes

BACKGROUND/AIMS

Peripheral blood CD8+ lymphocytes that home to mucosal surfaces express the human mucosal lymphocyte antigen (HML-1). At mucosal surfaces, including the ocular surface, only intraepithelial CD8+ lymphocytes express HML-1. These lymphocytes are retained in the intraepithelial compartment by virtue of the interaction between HML-1 and its natural ligand, E-cadherin, which is expressed on epithelial cells. The purpose of this study was to determine whether ocular surface epithelial cells (ocular mucosa) could induce the expression of human mucosal lymphocyte antigen on peripheral blood lymphocytes.

METHODS

Human corneal and conjunctival epithelial cells were co-cultured with peripheral blood lymphocytes. Both non-activated and activated lymphocytes were used in the experiments. After 7 days of incubation, lymphocytes were recovered and analysed for the antigens CD8/HML-1, CD4/HML-1, CD3/CD8, CD3/CD4, CD3/CD25, CD8/CD25, and CD4/CD25 by flowcytometry.

RESULTS

Significant statistical differences were observed in the CD8/HML-1 expression when conjunctival epithelial cells were co-cultured with non-activated and activated lymphocytes (p = 0.04 for each) and when corneal epithelial cells were co-cultured with non-activated lymphocytes (p = 0.03). Significant statistical difference in CD4/HML-1 expression was observed only when conjunctival epithelial cells were co-cultured with activated lymphocytes (p = 0.02).

CONCLUSION

Ocular surface epithelial cells can induce the expression of human mucosal lymphocyte antigen on CD8+ (and to some extent on CD4+) lymphocytes. This may allow the retention of CD8+ and CD4+ lymphocytes within the epithelial compartment of the conjunctiva and play a part in mucosal homing of lymphocytes.

Development of organised conjunctival leucocyte aggregates after corneal transplantation in rats

AIM

To investigate the development of lymphoid aggregates in the conjunctiva after corneal transplantation in rats.

METHODS

LEW or PVG strain corneas were transplanted orthotopically to PVG rats. Cornea and conjunctiva were examined clinically for up to 42 days. Eyes were removed with attached conjunctiva on days 10 and 15 after transplantation (before and during rejection), together with normal eyes, fixed, paraffin embedded, and examined immunohistochemically.

RESULTS

Clinically, the temporal half of the upper palpebral conjunctiva of recipients of 10/19 allografts and 1/10 isografts developed pronounced swelling, correlating with inflammation and rejection. Histologically, the swelling comprised leucocytic aggregates with an altered overlying epithelium. Aggregates contained granulocytes, macrophages, and cells expressing major histocompatibility complex (MHC) class II, CD4, and CD8, all more numerous in allograft associated conjunctiva. Class II+ cells were more abundant at the surface, whereas macrophages and T cells were more numerous in the deeper stroma. There were few B cells. There was greater CD54 expression by vascular endothelium in allograft associated aggregates. Cells expressing TNFalpha and IFNgamma but not IL1beta were present in stromal and superficial areas.

CONCLUSIONS

Corneal transplantation in rats induces the development of organised conjunctival leucocytic aggregates in a fixed location that are significantly more pronounced in recipients of allografts compared with isografts and show characteristics of a Th1 type immune response. These aggregates have characteristics of conjunctiva associated lymphoid tissue and may be sites of presentation of graft antigens and lymphocyte proliferation at the ocular surface.

Apafant, a Potent Platelet-Activating Factor Antagonist, Blocks Eosinophil Activation and Is Effective in the Chronic Phase of Experimental Allergic Conjunctivitis in Guinea Pigs

Platelet-activating factor (PAF) plays important roles in allergic reactions. In particular, there are many concerns about PAF, eosinophils, and the chronicity of allergic diseases. The purpose of the present studies is to elucidate the role of PAF in eosinophil activation at conjunctiva and to confirm the efficacy of Apafant (a potent PAF antagonist) ophthalmic solution in chronic experimental allergic conjunctivitis. Guinea pigs were actively immunized and allergic conjunctivitis was induced by repetitive instillation of 2.5% ovalbumin. PAF solution was topically applied and eosinophil activation was assessed by measuring the eosinophil peroxidase (EPO) activity in the tear fluid. Itch-scratching episodes and clinical symptoms scores were evaluated in the repetitive challenge conjunctivitis. From the instillation of PAF solution into guinea pig eyes, which were in a state of chronic allergic conjunctivitis, a significant increase in EPO activity was observed, and this increase was inhibited by pre-treatment with Apafant. In the repetitive challenge model, the animals treated with Apafant ophthalmic solution showed a significant reduction of clinical symptoms and the itch-scratch response in both the first and the second challenges. PAF has an activity, that induces mediator release from eosinophils in the conjunctival tissues and may be involved in the chronic phase of allergic conjunctivitis.

Mucous membrane pemphigoid and pseudopemphigoid

PURPOSE

To describe the clinical characteristics of patients with mucous membrane pemphigoid (MMP) and pseudopemphigoid.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Two hundred eighty consecutive patients referred for the evaluation of possible ocular MMP from January 1, 1985, to December 31, 2001.

METHODS

Information on patients presenting for evaluation of possible MMP was entered prospectively into a database, which was supplemented by a retrospective chart review. Mucous membrane pemphigoid was diagnosed in patients with a compatible clinical picture by the linear deposition of antibodies to the basement membrane zone (BMZ) on direct immunofluorescent analysis of a mucous membrane biopsy specimen or by the presence of circulating autoantibodies to epithelial BMZ.

MAIN OUTCOME MEASURES

Demographic and clinical characteristics of MMP and pseudopemphigoid; risk of ocular MMP among patients presenting with extraocular MMP without ocular disease.

RESULTS

Among patients with ocular MMP, extraocular disease was common (82.4% of patients). The risk of ocular involvement among patients with MMP seen without ocular disease was approximately 5% per year over the first 5 years of follow-up (cumulative risk at 5 years, 22%). Although immunohistologic confirmation of the diagnosis was obtained in all patients, the initial conjunctival biopsy was positive for MMP in 80% of the patients diagnosed with ocular MMP. The most frequent presumed causes of pseudopemphigoid were topical glaucoma medications (28.3%), rosacea blepharoconjunctivitis (20.0%), atopic keratoconjunctivitis (8.3%), and conjunctival lichen planus (8.3%).

CONCLUSIONS

Patients with ocular MMP typically have other systemic manifestations of MMP. Patients who are initially seen with extraocular MMP without ocular involvement are at risk for ocular disease developing. The clinical characteristics of ocular MMP and pseudopemphigoid are similar; therefore, immunohistologic evaluation of biopsied tissue is needed to confirm the diagnosis of MMP.

Nadroparine inhibits the hypersensitivity response in the conjunctiva

This study sought to investigate the effects of nadroparine on an in vivo experimental model of type I hypersensitivity response in the rat conjunctiva. Following drug application onto the eye, either before or after challenge with the mast cell degranulator, basic polyamine compound 48/80, the conjunctival histamine content and the nitrite levels in the conjunctival lavage fluid were quantified fluorometrically and spectrophotometrically, respectively. Instillation into the eye of nadroparine inhibited the C48/80-induced decreases in conjunctival histamine and the delayed increases in nitrite levels, without influencing basal mediator levels. Protamine did not induce histamine release and only partially reversed the effects of nadroparine post-challenge, yet it had no effect on the protective action of the drug when administered prior to degranulation. The results showed that nadroparine was equally effective in attenuating the effects of compound 48/80 in the eye when administered topically either before or after challenge.

Ag-specific recognition, activation, and effector function of T cells in the conjunctiva with experimental immune-mediated blepharoconjunctivitis

PURPOSE

To investigate antigen (Ag) specificity, activation, and effector function of the Ag-specific T cells involved in the development of experimental immune-mediated blepharoconjunctivitis (EC), an experimental conjunctivitis.

METHODS

EC was induced in Brown Norway rats by injection of ovalbumin (OVA)-specific T cells followed by OVA challenge with eye drops. Eyes, including the conjunctivas, were harvested at different time points after challenge. The dependence of EC onset on the challenging Ag was assessed by challenge with an irrelevant Ag or stimulatory OVA peptides. To show the infiltration of transferred T cells into the conjunctiva, T cells were labeled with 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE) before transfer. The activation of T cells in the conjunctiva was assessed by measuring phosphorylation of Lck-associated molecules by Western blot analysis. Conjunctivas were also examined by immunohistochemistry and used for reverse transcription-polymerase chain reaction to determine the phenotype of the infiltrating cells and cytokine, chemokine, and chemokine receptor expression. To investigate infiltration of non Ag-specific T cells into the conjunctiva, ragweed (RW)-primed lymphocytes were transferred into OVA-specific T-cell receptor transgenic (DO11.10) mice. The mice were then challenged with RW and the conjunctivas were harvested for immunohistochemistry to detect T cells derived from DO11.10 mice.

RESULTS

EC was induced only when challenged with OVA protein or stimulatory OVA peptides, and CFSE-labeled transferred cells were found in the conjunctiva. Phosphorylation of Lck and an 85-kDa Lck-associated molecule were observed in the conjunctiva 6 hours after challenge. Many cytokines and chemokines began to be expressed at 6 hours, and individual expression patterns over time correlated well with the infiltration patterns of different inflammatory cells. In DO11.10 mice that received RW-primed lymphocytes, T cells derived from the recipient mice infiltrated the conjunctiva after RW challenge.

CONCLUSIONS

Ag-specific T cells initiate EC by first infiltrating the conjunctiva, where they become activated by the specific Ag in the conjunctiva.

[Flow cytometric analysis of HLA-DR, IL-6 and IL-8 expression by conjunctival epithelial cells from patients with prolonged topical antiglaucoma treatments]

AIM OF THE STUDY

To investigate the expression of three inflammation markers, HLA-DR, IL-6, and IL-8, by conjunctival epithelial cells obtained using impression cytology (IC) samples from long-term treated glaucoma patients.

PATIENTS AND METHODS

IC samples were obtained from the 60 following individuals: 45 patients suffering from primary open-angle glaucoma and receiving topical treatments for at least 1 year and 15 subjects with no ophthalmological disease (controls). Membrane expression of HLA-DR and intracellular expression of IL-6 and IL-8 were quantified, respectively, by indirect and direct immunofluorescence techniques. Fluorescence levels were quantified using calibrated fluorescent beads.

RESULTS

The percentage of HLA-DR-positive cells was significantly higher on IC samples from multitreated glaucoma patients and from patients treated by either preserved betablocker or preserved prostaglandin analogue than on IC samples from control individuals. Interestingly, the percentage of HLA-DR-positive cells was not significantly increased upon treatment with unpreserved betablocker. However, the percentage of IL-6- and IL-8-positive cells as well as IL-6 and IL-8 expression levels was significantly higher in patients than in controls, regardless of the treatment type and the presence of preservative. A significant positive correlation was found between HLA-DR and cytoplasmic IL-6 expression, between HLA-DR and cytoplasmic IL-8 as well as between IL-6 and IL-8 cytoplasmic expressions.

CONCLUSION

The present study confirms that there is an increased expression of HLA-DR in treated glaucoma patients compared to controls and demonstrates that antiglaucoma treatments lead to increased IL-6 and IL-8 expressions. It also indicates that benzalkonium-preserved eyedrops and preserved multitherapy may induce stronger inflammatory responses than do unpreserved eyedrops, although further studies are needed to determine the respective inflammatory role of preservative and therapeutic molecules. In this study, flow cytometry was used to detect the intracellular pro-inflammatory cytokines in conjunctival cells obtained by impression cytology. This standardized and reliable technique was a useful tool to assess inflammatory and allergic ocular surface disorders.

Conjunctival allergen challenge: models in the investigation of ocular allergy

Recently, the number of agents to treat ocular allergy has increased dramatically, from three (pheniramine, antazoline, cromolyn) to more than a dozen. A general increase in the incidence of atopy in recent years and the fact that patients are becoming less tolerant of bothersome signs and symptoms have been driving forces in this increase. As visual tasking, such as reading and working on a computer, has become more prevalent, there is an increased awareness of ocular allergy and the impact it has on quality of life and productivity at work and school. With the need for more effective medications, the development of models, such as the conjunctival allergen challenge (CAC), has made the identification of new agents more efficient. In this article, we review the relevant background on the science behind allergen challenges in the eye, how models are designed, and how models are used in the field today.

Skin tests and conjunctival and bronchial challenges with extracts of Blomia tropicalis and Dermatophagoides pteronyssinus in patients with allergic asthma and/or rhinoconjunctivitis

BACKGROUND

Blomia tropicalis and Dermatophagoides pteronyssinus are important mite species in Tenerife, Canary Islands, Spain. Several studies have demonstrated a variable degree of allergenic cross-reactivity in vitro. However, only a few have addressed their allergenic cross-reactivity using challenge tests.

OBJECTIVE

The objective of this study was to conduct conjunctival and bronchial challenge tests with B. tropicalis and D. pteronyssinus extracts in a group of 42 patients with allergic asthma and/or rhinoconjunctivitis sensitised to house dust mites (31 females, 11 males; mean age 21.7 +/- 7.02 years).

METHODS

Prick tests using standardised extracts and specific IgE determinations using the CAP system were performed. Bronchial and/or conjunctival challenges were conducted using freeze-dried extracts of both mite species. A patient was considered sensitive to a mite species if she/he had a positive prick and/or CAP test result. A total of 32 conjunctival and 15 bronchial challenges were performed with both mite species.

RESULTS

Prick tests were positive to B. tropicalis in 23 patients (54.7%) and to D. pteronyssinus in 41 (97.6%). One patient (2.4%) was exclusively sensitive to B. tropicalis. The CAP test was positive for B. tropicalis in 28 patients and for D. pteronyssinus in 41. Conjunctival challenges to B. tropicalis were positive in 20 patients (18 sensitised and 2 non-sensitised) and negative in 12 (5 sensitised and 7 non-sensitised patients). Conjunctival challenges with D. pteronyssinus were positive in all 31 D. pteronyssinus-sensitised patients who underwent conjunctival challenges. Bronchial challenges with B. tropicalis were positive in 9 sensitised patients and negative in 6 patients (2 sensitised and 4 non-sensitised). Bronchial challenges with D. pteronyssinus were positive in all patients except 1, who only reacted to B. tropicalis.

CONCLUSIONS

Allergens of the mite species B. tropicalis induce positive conjunctival and bronchial challenges in B. tropicalis-sensitised individuals. Our results suggest that although there is a low to moderate degree of in vivo cross-reactivity between B. tropicalis and D. pteronyssinus, B. tropicalis seems to be a relevant source of allergens in areas where patients are exposed.

Structural and cellular architecture of conjunctival lymphoid follicles in the baboon (Papio anubis)

Conjunctival lymphoid follicles (CLFs), present in normal individuals, undergo hyperplasia upon conjunctival infection by a specific array of pathogens; infection-associated enlargement of draining preauricular lymph nodes suggests that conjunctival follicles participate in the afferent limb of acquired immune responses for the ocular surface. The present study was performed to delineate the structural and lymphoid anatomy of CLFs in the baboon (Papio anubis), a non-human primate conjunctival model with close similarity to the human. Conjunctiva from both eyes, along with mesenteric lymph node, spleen, tonsil, and ileum controls were harvested from ten baboons at necropsy, and studied by histochemical and immunohistochemical methods. Baboon conjunctival follicles were identified as dense oval collections of leukocytes in the substantia propria with infiltration into a thinned overlying conjunctival epithelium. Goblet cells were universally absent, the overlying mucin layer was attenuated, and the follicle-associated epithelium (FAE) demonstrated comparatively diminished alkaline phosphatase expression. The basement membrane overlying each follicle appeared discontinuous. CD4-positive T lymphocytes were distributed in parafollicular areas and to a lesser degree in follicle germinal centers. B lymphocytes formed the predominant cell in follicles, and also heavily infiltrated the FAE. B cell IgM expression was prominent in germinal centers, while IgD staining occurred in a horseshoe-shaped distribution in the follicle mantle zone. Although B cell IgA expression was noted in the non-follicular conjunctiva, IgA expression was inconspicuous within conjunctival follicles. S-100- and CD1a-positive dendritic cells were found in FAE, while fascin-positive mature dendritic cells appeared in the deeper areas of each follicle. CD68-positive macrophages were dispersed throughout the follicles. CD35-positive follicular dendritic cells were observed only in germinal centers. CLFs appear highly organized consistent with a role in the adaptive immune response to conjunctival pathogens.

[Corneal complications after hematopoietic stem cell transplantation]

AIM

To evaluate the incidence and clinical course of corneal complications in patients with severe dry eye syndrome after hematopoietic stem cell transplantation (HSCT).

PATIENTS AND METHODS

50 consecutive patients (aged 9-65 years; average=42+/-11 years) with Sjögren-like syndrome after hematopoietic stem cell transplantation were examined. In order to assess the severity of the dry eye syndrome, the frequency of blinking and break-up time were determined and Schirmer-I, fluorescein,and rose bengal tests were carried out. Biopsy and histological examination were performed in cases with suspected conjunctival graft-versus-host reaction.

RESULTS

Patients with Sjögren-like dry eye syndrome were referred within an average of 13 months after HSCT (SD+/-20 months).The follow-up was up to 83 months (mean: 10.2 months,SD+/-14.97). Of the 50 patients 15 developed severe corneal complications with significant loss of vision which resulted in enucleation of the eye in 1 patient. Of these 15 patients 4 had a viral and 2 a bacterial keratitis,7 had trophic corneal thinning and sterile ulcers. Two patients had limbal stem cell insufficiency or pseudomembranous conjunctivitis, both due to conjunctival graft-versus-host reaction. Another patient developed a toxic keratopathy, probably induced by cyclosporin A eye drops. Of 50 patients 35 presented with signs of an inactive or active conjunctival graft-versus-host reaction which could be proven histologically in 26 patients.

DISCUSSION

Patients with Sjögren-like dry eye syndrome after hematopoietic stem cell transplantation are at high risk to develop corneal complications.These complications may result from an aggressive extension of the graft-versus-host reaction towards the conjunctiva and/or the lacrimal gland and seem to occur more often during the period of reduction of systemic immunosuppressive therapy.Furthermore, infectious as well as trophic or toxic corneal complications may be supported by local immunosuppressive therapy. We suggest frequent ophthalmological checks of patients receiving hematopoietic stem cell transplantation who need local immunosuppressive therapy or are in the phase of reduction of systemic immunosuppressive therapy

Conjunctival provocation tests in the diagnosis of Anisakis simplex hypersensitivity

INTRODUCTION

The prevalence of positive skin tests to Anisakis simplex is high compared with the low incidence of true gastroallergic Anisakiasis. There is little information about the prevalence of positive conjunctival tests in A. simplex-sensitized individuals. This study assesses the predictive value of conjunctival provocation test in two groups of A. simplex-sensitized subjects and negative controls.

METHODS

Group A consisted of 28 individuals with a clinical history strongly suggestive of gastroallergic anisakiasis and group B, of 32 individuals without such history. The 60 individuals had positive skin tests and in vitro specific IgE determinations to A. simplex. Skin and conjunctival provocation tests were performed with an extract of A. simplex at a concentration of 1 mg of lyophilized material per ml.

RESULTS

Conjunctival provocation tests were positive in 21/28 (75%) of group A patients and in 10/32 (31%) of group B patients. This difference was statistically significant (p < 0.015); the odds ratio was 6.6 (2.11-20.5; p < 0.05). The diagnostic value of the conjunctival provocation test was expressed by the following statistical indicators: sensitivity 75% (55.8%-88.6%), false positive 25% (11.4%-45.2%), specificity 68.7% (49.9%-83.2%), false negative 31.2% (16.7%-50%), positive predictive value 67.7% (48.5%-82.7%), negative predictive value 75.9% (56.1%-89%), Yuden index 1.43. There were no statistical differences related to age, sex, or atopic status in patients with a positive or negative conjunctival challenge. Total and specific IgE levels to A. simplex were significantly greater (p < 0.05 and p < 0.001, respectively) in the group of patients with a positive challenge.

CONCLUSIONS

The results demonstrate that positive conjunctival provocation tests and high specific and total IgE levels are more prevalent in patients with a clinical history strongly suggestive of gastroallergic anisakiasis. Despite the significant differences obtained in both groups, this test has a limited diagnostic value to clinically discriminate patients with a history consistent with gastroallergic anisakiasis.

Survival of allografted pancreatic islets in the subretinal space in rats

The purpose of this study was to determine whether the subretinal space would provide immune privilege for pancreatic islet transplantation. Islets from outbred Sprague Dawley (SD) rats were isolated by collagenase digestion, and about 200 handpicked islets were transplanted into the subretinal space of SD rats. Similar grafts were transplanted into the subconjunctival space of SD rats as controls. Transplanted eyes were enucleated after 2 to 60 days, fixed and embedded in paraffin for immunoperoxidase staining of insulin, glucagon, and CD8+ lymphocytes. Clinical examination of rat eyes revealed minimal or no inflammation in the anterior chamber or vitreous at any time point. Fifteen of 19 subretinal allografts survived up to 60 days. Few CD8+ lymphocytes were present in the subretinal grafts and the endocrine cells stained intensely for insulin and glucagon at all time points. In contrast, CD8+ lymphocytes were present in subconjunctival grafts in rats by day 14 and all grafts were destroyed by day 21. These results suggest that the subretinal space provides immune privilege for islet allotransplantation by preventing massive lymphocyte infiltration.

Differential expression and signaling of IFN-gamma in the conjunctiva between Lewis and Brown Norway rats

Genetic background determines the histological features of experimental immune-mediated blepharoconjunctivitis (EC) in rats, which is a model for human allergic conjunctivitis (AC). A great number of lymphocytes predominate in EC of Lewis rats, while less lymphocytes and more eosinophils are present in that of Brown Norway (BN) rats. Although this difference could be attributed to their systemic Th1/Th2 dominancy, it remains unclear whether some regulatory mechanisms may exist in the inflammatory site in the conjunctiva. Here, we aim to investigate this hypothesis by comparing the expression levels of inflammatory mediators in the conjunctiva between the two strains. EC was induced in Lewis and BN rats by transfer of ovalbumin (OVA)-specific CD4(+) T-cell lines followed by eye drops of OVA as antigen challenge, and then was clinically and histologically evaluated. Reverse-transcription (RT)-PCR was performed to compare the expressions of cytokines and cytokine receptors (Rs) in conjunctivas of both strains of rats either with or without EC. To confirm the biological significance of interferon (IFN)-gamma R expression, phosphorylation of signal transducers and activators of transcription (STAT)-1 was examined in the conjunctivas, followed by subconjunctival injection of IFN-gamma. BN T cells contained interleukin (IL)-4 and IFN-gamma, while Lewis T cells expressed no IL-4. Transfer of those cells induced more severe EC in Lewis rats. RTPCR using naive conjunctivas detected more IL-4, IFN-gamma, and IFN-gamma R beta-chain RNA expression in BN rats. After the EC induction, BN rats expressed significantly higher amounts of IFN-gamma R beta-chain, and upregulation of interferon regulatory factor (IRF)-1 was observed. Phosphorylation of STAT-1 was more remarkable in BN rats. The findings demonstrate differential expression of IFN-gamma R and signaling through IFN-gamma in the conjunctiva between the two strains. This may be due to differences in histopathological character between the two strains.

Efficacy of indomethacin 0.1% and fluorometholone 0.1% on conjunctival inflammation following chronic application of antiglaucomatous drugs

BACKGROUND

Subclinical conjunctival inflammation has been shown to have a deleterious effect on the outcome of filtering surgery. The study was designed to assess the efficacy and safety of a non-steroidal anti-inflammatory ophthalmic solution (preservative-free indomethacin 0.1%) on conjunctival inflammation following chronic application of antiglaucomatous drugs, in comparison with a steroidal ophthalmic solution (preserved fluorometholone).

METHODS

Eighty-nine glaucomatous patients were included in a randomised, multicentre study comparing two parallel groups of treatment given on the basis of 1 drop 4 times daily for 1 month before filtering surgery. Patients had been treated with one or more antiglaucomatous drugs for at least 3 years. The routine antiglaucomatous treatment was continued during the study. Evaluations were carried out at baseline and after 30 days of treatment. Conjunctival inflammation was assessed under masked conditions by means of conjunctival impression analysis which determined the percentage of cells expressing HLA-DR. The ocular surface was also examined using the fluorescein test and lissamine green staining.

RESULTS

Paired conjunctival impression specimens available both on day 0 (D0) and day 30 (D30) involved 49 patients. Among them, 34 eyes had a positive expression of HLA-DR at inclusion. On D30, in patients positive to HLA-DR on D0, the percentage of cells expressing HLA-DR had significantly decreased in both treatment groups: the mean reduction was 29.7% from a baseline value of 51.4% in the indomethacin group ( P=0.019) and 32.5% from a baseline value of 48.7% in the fluorometholone group ( P<0.001). There was no significant difference between groups. Seven cases of drug-related superficial punctate keratitis were observed on D30 by means of a fluorescein test: one in the indomethacin group and six in the fluorometholone group.

CONCLUSION

Both anti-inflammatory eyedrops were effective in reducing subclinical conjunctival inflammation before filtering surgery. Regarding superficial punctate keratitis, the corneal tolerance of preservative-free indomethacin 0.1% eyedrops seemed to be better than that of preserved fluorometholone eyedrops.

Expression of T lymphocyte chemoattractants and activation markers in vernal keratoconjunctivitis

BACKGROUND/AIMS

T lymphocytes are present in increased numbers in the conjunctiva of patients with vernal keratoconjunctivitis (VKC) and their activation has a central role in the pathogenesis of the chronic allergic inflammatory reactions seen in VKC. The aims of this study were to examine the expression of three recently described potent T lymphocyte chemoattractants, PARC (pulmonary and activation regulated chemokine), macrophage derived chemokine (MDC), and I-309, the MDC receptor CCR4, and T lymphocyte activation markers, CD25, CD26, CD62L, CD71, and CD30, and to correlate them with the counts of CD3(+) T lymphocytes in the conjunctiva of patients with VKC.

METHOD

Conjunctival biopsy specimens from 11 patients with active VKC, and eight control subjects were studied by immunohistochemical techniques using a panel of monoclonal and polyclonal antibodies directed against PARC, MDC, I-309, CCR4, CD25, CD26, CD62L, CD71, and CD30. The numbers of positively stained cells were counted. The phenotype of inflammatory cells expressing chemokines was examined by double immunohistochemistry.

RESULTS

In the normal conjunctiva, vascular endothelial cells in the upper substantia propria showed weak immunoreactivity for CD26. There was no immunoreactivity for the other antibodies. VKC specimens showed inflammatory cells expressing PARC, MDC, and I-309. The numbers of PARC(+) inflammatory cells were higher than the numbers of MDC(+) and I-309(+) inflammatory cells and the mean values of the three groups differed significantly (17.0 (SD 10.1); 9.5 (9.9), and 4.3 (7.9), respectively, p = 0.0117, ANOVA). The numbers of PARC(+) inflammatory cells had the strongest correlation with the numbers of CD3(+) T lymphocytes. Few CCR4(+) inflammatory cells were observed in only three specimens. Double immunohistochemistry revealed that all inflammatory cells expressing chemokines were CD68(+) monocytes/macrophages. The numbers of CD25(+) T lymphocytes were higher than the numbers of CD26(+), CD62L(+), CD71(+), and CD30(+) T lymphocytes and the mean values of the five groups differed significantly (46.2 (27.9), 30.7 (16.0), 20.1 (8.6), 7.8 (7.7), and 6.5 (4.0), respectively, p <0.001, ANOVA). The numbers of CD25(+) T lymphocytes had the strongest correlation with the numbers of CD3(+) T lymphocytes.

CONCLUSION

These results suggest a potential role for PARC, MDC, and I-309 in attracting T lymphocytes into conjunctiva in VKC. T lymphocytes in VKC are activated and express several activation markers which might contribute to the pathogenesis of VKC.

Exertion of the suppressive effects of IFN-gamma on experimental immune mediated blepharoconjunctivitis in Brown Norway rats during the induction phase but not the effector phase

BACKGROUND/AIMS

Interferon gamma (IFN-gamma) knockout mice exhibit severe allergic conjunctivitis (AC), indicating that IFN-gamma regulates the development of AC. The authors examined whether this inhibitory effect of IFN-gamma is exerted during the induction or effector phase of experimental AC.

METHODS

Experimental immune mediated blepharoconjunctivitis (EC) was induced in Brown Norway (BN) rats, using ovalbumin (OVA) as the antigen. To investigate the role of IFN-gamma in the induction phase, EC was induced by active immunisation and IFN-gamma (10 micro g/time, total 70 micro g), or phosphate buffered saline (PBS) as a control, was injected intraperitoneally every other day from the day of immunisation. The rats were challenged with OVA eye drops 13 days after immunisation, and 24 hours later, the eyes were harvested for histology. To examine the effects of IFN-gamma in the effector phase, OVA specific T cells were transferred into syngeneic rats and IFN-gamma (10 micro g/time, total 50 micro g) or PBS was injected each day after the transfer until induction of EC 4 days later with an OVA challenge. To investigate the role of endogenous IFN-gamma during the effector phase, an anti-IFN-gamma monoclonal antibody (3 mg/time) was injected on days 3 and 4.

RESULTS

Injection of IFN-gamma into actively immunised rats suppressed eosinophilic infiltration but not infiltration of mononuclear cells. In contrast, neither IFN-gamma nor anti-IFN-gamma affected EC in passively immunised rats.

CONCLUSION

IFN-gamma is a suppressive cytokine for the development of EC and exerts this suppressive effect during the induction phase.

Immunohistochemical HLA-DR antigen expression with lymphocyte subsets and proliferative activity in pterygium

The immunohistochemical expression of HLA-DR antigen, CD8, CD4, CD68, S1OO, PCNA and Ki-67 was performed in order to investigate the role of immune mechanisms in pterygium, in correlation with proliferative activity. A series of 98 surgically-excised pterygia, 18 pingueculae and 20 normal conjunctivae, was studied by the avidin-biotin method, on formalin-fixed, paraffin-embedded tissue. HLA-DR antigen was abundantly expressed in pterygium epithelial cells, whereas almost no expression was found in pinguecula and normal conjunctiva. A high value of Ki-67 and PCNA expression coexisted in the same areas with HLA-DR antigen expression in pterygium and a statistically significant positive correlation resulted between them (p = 0.002). Aberrant infiltration of inflammatory cells (CD4, CD8, CD68, S100) was detected in pterygium, while lower densities were found in pinguecula and conjunctiva. The data suggest that immunopathological mechanisms may contribute in the pathogenesis of pterygium. In addition, the aberrant HLA-DR antigen expression seems to be correlated with the growth fraction of the lesion.

Conjunctival macrophage-mediated influence of the local and systemic immune response after corneal herpes simplex virus-1 infection

Recently it has been shown that selective subconjunctival macrophage depletion reduced the incidence and severity of stromal herpes simplex virus (HSV) keratitis in mice. In this study, we examined the effect of conjunctival macrophage depletion on the corneal and systemic T-cell-mediated immune response. BALB/c mice were treated with subconjunctival injections of dichloromethylene diphosphonate (Cl2MDP)-liposomes (Cl2MDP-LIP) or phosphate-buffered saline (PBS) 7 and 2 days before corneal infection with 105 plaque-forming units (PFU) of HSV-1 (KOS strain). Interferon (IFN)-gamma, interleukin (IL)-2, and IL-4 production in the cornea was analysed by enzyme-linked immunosorbent assay (ELISA), and cytokine mRNA levels (IFN-gamma, IL-4) were measured by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Cell culture supernatants from submandibular lymph nodes were analysed by ELISA for expression of IFN-gamma, IL-2, and IL-4 and by bioassay for IL-6. The HSV-1-specific proliferative response of lymphocytes from regional lymph nodes and the delayed-type hypersensitivity (DTH) response were tested after corneal infection. Virus-neutralizing antibody titres and HSV-1-specific immunoglobulin G (IgG)2a/IgG1-ratios were measured. Cytokine mRNA expression (IFN-gamma, IL-4) and secretion (IFN-gamma, IL-2, IL-4) in the corneas were decreased after HSV-1 corneal infection in the macrophage-depleted mice. The secretion of IFN-gamma and IL-2 was decreased in the regional lymph nodes from Cl2MDP-LIP-treated animals (P<0.05). Furthermore, Cl2MDP-LIP-treated mice had decreased HSV-1 specific proliferative responses (P<0.05) and DTH response after corneal HSV-1 infection (P<0.05). The virus-neutralizing serum-antibody levels (P<0.05) increased while the HSV-1 specific IgG2a/IgG1-ratio was unaffected after macrophage depletion. Macrophage depletion did not induce a shift between the T helper 1 (Th1) and Th2 response in this HSK model. The data suggest that conjunctival macrophage functions are enhancing the T-cell-mediated immune response after corneal infection. This effect is at least in part responsible for the impaired course of herpetic keratitis after macrophage depletion.

The inflammatory milieu associated with conjunctivalized cornea and its alteration with IL-1 RA gene therapy

PURPOSE

This study was designed to gain an insight into the inflammatory milieu into which a donor limbal graft is routinely introduced. The objective of this study was to modulate this environment by gene therapy with the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1 RA).

METHODS

In a mouse model, the ocular surface cytokine environment associated with a conjunctivalized cornea was assessed 4 weeks after injury. Total corneal epithelial and limbal debridement was performed with a combination of alkali and scrape injury. The cytokines and adhesion molecules measured included IL-1alpha, IL-1beta, IL-6, VEGF, intercellular adhesion molecule (ICAM)-1, and vascular adhesion molecule (VCAM)-1, by real-time PCR or ELISA. Injured corneas were transfected with IL-1 RA by injection of naked plasmid vector pIRES-EGFP-IL-1 RA immediately after injury. Corneas transfected with pIRES-EGFP served as the control. Expression of corneal IL-1 RA after transfection with pIRES-EGFP-IL1-RA was assessed over a 2-week period by real-time PCR and Western blot analysis. In addition, limbal stem cell grafts transfected with IL-1 RA were assessed for leukocyte influx.

RESULTS

Conjunctivalized corneas showed increased expression of IL-1alpha, IL-1beta, IL-1 RA, IL-6, VEGF, ICAM-1, and VCAM-1, compared with normal cornea. Transfection-efficiency experiments indicated that corneal expression of IL-1 RA peaked between 12 and 24 hours and lasted up to 2 weeks after the initial transfection. IL-1 RA corneal gene therapy resulted in a downregulation of IL-1beta and VCAM-1 expression at 4 weeks after injury, whereas downregulation of IL-6 was evident only at 1 week after injury. Corneal neovascularization was also reduced. In addition, corneal limbal stem cell grafts transfected with IL-1 RA showed a decreased leukocyte influx compared with control grafts.

CONCLUSIONS

Transfection of a cornea with IL-1 RA immediately after epithelial injury selectively altered the cytokine profile of the resultant conjunctivalized cornea and suppressed corneal neovascularization. Transfection of corneal limbal donor tissue with IL-1 RA before engraftment can reduce leukocyte influx into the graft. The findings demonstrate the feasibility of using transient cytokine gene expression, either in donor or recipient corneal tissue, to alter the ocular surface environment beneficially.

Conjunctival T-cell subpopulations in Sjögren's and non-Sjögren's patients with dry eye

PURPOSE

To examine the conjunctiva of patients with Sjögren's syndrome keratoconjunctivitis sicca (SS-KCS) and non-Sjögren's keratoconjunctivitis sicca (NS-KCS) for evidence of immune-based inflammation.

METHODS

Conjunctival biopsy specimens were obtained from 15 patients with SS-KCS and 15 with NS-KCS. Immunohistochemistry was performed on frozen sections to characterize and quantify T-cell subtypes (CD3, CD4, and CD8) and markers of immune activation (major histocompatibility complex [MHC] class II: HLA-DR, HLA-DQ) and inflammation (intercellular adhesion molecule [ICAM]-1). The numbers of cells positive for each marker were counted by two masked observers and averaged.

RESULTS

Conjunctival biopsy specimens from patients with SS-KCS or NS-KCS revealed lymphocytic infiltration and increased immunoreactivity for the markers of inflammation and immune activation. The extent of cellular immunoreactivity did not differ significantly between SS-KCS and NS-KCS tissue samples.

CONCLUSIONS

The authors' findings indicate that patients with SS-KCS or NS-KCS have conjunctival inflammation manifested by inflammatory cell infiltrates and upregulation of expression in markers of immune activation. Clinical symptoms of KCS may be more dependent on T-cell activation and resultant inflammation than previously believed. In addition to tear substitutes, anti-inflammatory therapeutics should be investigated for the treatment of KCS.

Characterization of CD95 ligand (CD95L)-induced apoptosis in human tenon fibroblasts

Toxic side effects of cytotoxic agents such as 5-fluorouracil or mitomycin-C in glaucomatous filtering procedures call for alternative approaches to control fibroblast proliferation. CD95L is a death ligand that triggers apoptosis in susceptible target cells. Apoptosis allows for the safe disposal of cells without damaging the surrounding tissue. The goal of this study was to characterize and to evaluate the CD95L induced cell death in cultured Tenon fibroblasts. Human Tenon fibroblasts were treated with different concentrations of CD95L. For comparison, murine NIH 3T3 fibroblasts were used. Immunohistochemistry and Western blot were used to investigate the CD95 and CD95L expression. Cytotoxicity was measured by crystal violet assay. Apoptosis was investigated using in situ DNA end labelling (TUNEL). DEVD-AMC caspase 3 like activity was measured and caspase 3 processing was studied by immunoblot and the use of the caspase inhibitor DEVD-CHO in cell culture assays. Tenon and NIH 3T3 fibroblasts express CD95 and CD95L. The authors found concentration dependent inhibition of proliferation after CD95L treatment. Tenon fibroblasts, but not NIH 3T3 fibroblasts, show synergy when combined with actinomycin D or cyclohexamide. CD95L treatment did not alter total protein or RNA synthesis. Cell death induced by CD95L was apoptotic and activated caspase 3, as TUNEL positive cells and the active fragment of caspase 3 were found. CD95L induced cell death could be inhibited by the caspase-inhibitor.Here, it is demonstrated that the CD95L induced cell death in cultured human Tenon fibroblasts is apoptotic and possibly mediated by the caspase 3 pathway. These results suggest that it may be possible to use CD95L in glaucomatous filtering procedures. In vivo studies are necessary for further evaluation.

Histological study of conjunctiva-associated lymphoid tissue in mouse

PURPOSE

To investigate conjunctiva-associated lymphoid tissue (CALT) in the mouse conjunctiva by histological methods.

METHODS

The presumed follicular tissue in the conjunctiva of normal mice, age ranging from 4 to 6 weeks, was histologically investigated by the hematoxylin-eosin staining method. Next, we treated the mice with topical instillation of a combined solution of ovalbumin and cholera toxin B to investigate the morphological changes of conjunctival follicles to antigen challenge. The treated mice underwent sequential clinical examinations, and the conjunctival follicular tissue was examined by an immunohistochemical method using anti-CD4 antibody, anti-CD8 antibody, and anti-S-100 antibody.

RESULTS

Follicular tissue was present on the mouse nictitating membrane. Both size and number of follicular tissue areas increased with topical ovalbumin treatment. Immunohistochemical study revealed CD4, CD8, and S-100 positive cells in the follicular tissue. The epithelial layer, corresponding to follicular tissue, demonstrated intra-epithelial pocket and the presence of CD4-positive cells in the intra-epithelial pocket.

CONCLUSION

Follicular tissue at the nictitating membrane is CALT in the mouse.

The central role of conjunctival mast cells in the pathogenesis of ocular allergy

Ocular allergic diseases are characterized by specific activation of conjunctival mast cells with subsequent release of preformed and newly formed mediators. Mast-cell numbers on the ocular surface are increased in all forms of allergic conjunctivitis. Mast-cell activation plays a central role in the development of the ocular allergic reaction, which can be divided into an early and a late inflammatory phase. Mast-cell mediators have been measured in tears of patients suffering from various forms of allergic conjunctivitis, and in sensitized patients after specific ocular allergen challenge. Histamine and tryptase are the most studied mediators in tears of allergic patients. Several cytokines, such as IL-4 and TNF-a, are also produced and released by conjunctival mast cells, and probably play a role in the immunoregulation on the ocular surface. In vitro studies of the characteristics and biologic functions of conjunctival mast cells highlight their central role in the pathogenesis of ocular allergy, and have led to new opportunities to evaluate anti-allergic compounds. This review discusses the role of conjunctival mast cells in the development of ocular allergic diseases.

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.

In vivo production of interferon beta by human Tenon's fibroblasts; a possible mediator for the development of chronic conjunctival inflammation

BACKGROUND

Chronic inflammation may develop from failure of the immune system to deactivate itself during resolution of the wound healing response, and is recognised as a major risk factor for trabeculectomy failure. Fibroblast/T cell interactions may contribute to aggressive scarring. Our previous research showed that in vitro human Tenon's fibroblast produced interferon beta was responsible for preventing T cell apoptosis, suggesting that this interaction could contribute to the development of chronic inflammation.

METHODS

Immunohistological techniques were used to investigate the in vivo components of this particular fibroblast/T cell interaction in conjunctival biopsies from glaucoma patients undergoing filtration surgery.

RESULTS

Fibroblast produced interferon beta and T lymphocytes were identified in human conjunctiva.

CONCLUSION

The components of fibroblast mediated prevention of T cell apoptosis were identified in vivo, suggesting that the development of this interaction is possible and that it may contribute to the development of chronic inflammation and excessive scarring.

Mast cells in the eyes of Calomys callosus(Rodentia: Cricetidae) infected by Toxoplasma gondii

The mast cell is a powerful effector cell for the innate immune system, acting through the secretion of several distinct mediators. Few studies have demonstrated the relationship between mast cells and toxoplasmosis. In this study, mast cells were investigated in two experimental Toxoplasma infections using Calomys callosus (Rodentia: Cricetidae) as the host. Animals were inoculated either intraperitoneally or via the conjunctiva with tachyzoites of Toxoplasma gondii (RH strain) and sacrificed after 5 days or 24 h, respectively. Enucleated eyes were processed for histological and ultrastructural analysis. Neither experimental infection altered the localization of mast cells compared to control eyes, but they did lead to an accumulation in some tissues as well as to their activation. There was a significant increase in the number of mast cells within 5 days and 24 h after infection. The ocular lesions were characterized by the presence of tachyzoites, inflammatory cells and vasodilatation in the iris and retina. In conclusion, mast cells were mobilized in these experimental infections, suggesting that they play an important role in the host inflammatory response after infection with T. gondii.

The conjunctival lymphoid follicle in mucosal immunology

The conjunctiva forms a continuous mucosal surface from the eyelid margin to the cornea, and makes contact with airborne antigens and those on the adjacent eyelid skin and preocular tear film. Conjunctival lymphoid follicles (CLF) undergo hyperplasia upon conjunctival infection by a specific array of pathogens; infection-associated enlargement of draining preauricular lymph nodes suggests that CLF participate in the afferent limb of acquired immune responses for the ocular surface. In this review, we examine the evidence for classification of CLF as part of the common mucosal immune system, and explore the possible therapeutic implications.

The role of histamine H(1) receptors in late-phase reaction of allergic conjunctivitis

The role of histamine H(1) receptors in the late-phase reaction of allergic conjunctivitis was studied using histamine H(1) receptor-deficient mice. To clarify the eosinophil infiltration, which is a reliable indicator of late-phase reaction, eosinophil peroxidase activity in the conjunctiva was measured. Mice were actively immunized with ovalbumin, and conjunctivitis was induced by topical instillation of ovalbumin. A significantly high eosinophil peroxidase level in the conjunctiva was observed in sensitized wild-type mice, whereas sensitized histamine H(1) receptor-deficient mice showed no significant increase in the conjunctival eosinophil peroxidase level. In addition, the elevation of eosinophil peroxidase level observed in sensitized wild-type mice was significantly antagonized by pretreatment with anti-P-selectin antibody. From these findings, it was concluded that eosinophil infiltration into the conjunctival tissue in late-phase reaction of allergic conjunctivitis is mediated by P-selectin stored in endothelial cells via histamine H(1) receptors.