Immunologic basis for development of keratoconjunctivitis sicca in systemic autoimmune diseases: Role of innate immune sensors

The literature is filled with citations reporting an increased incidence of chronic dry eye disease, also known as keratoconjunctivitis sicca, in patients with systemic autoimmune diseases such as rheumatoid arthritis, Sjögren's Syndrome, systemic sclerosis and lupus. As the most environmentally exposed mucosal surface of the body, the conjunctiva constantly responds to environmental challenges which are typically self limited, but when persistent and unresolved may provoke pathogenic innate and adaptive immune reactions. Our understanding of the pathophysiological mechanisms by which systemic autoimmune diseases cause dry eye inducing ocular surface inflammation continues to evolve. Conjunctival immune tone responds to self or foreign danger signals (including desiccating stress) on the ocular surface with an initial non-specific innate inflammatory response. If unchecked, this can lead to activation of dendritic cells that present antigen and prime T and B cells resulting in an adaptive immune reaction. These reactions generally resolve, but dysfunctional, hyper-responsive immune cells found in systemic autoimmune diseases that are recruited to the ocular surface can amplify inflammatory stress responses in the ocular surface and glandular tissues and result in autoimmune reactions that disrupt tear stability and lead to chronic dry eye disease. We here propose that unique features of the ocular surface immune system and the impact of systemic immune dysregulation in autoimmune diseases, can predispose to development of dry eye disease, and exacerbate severity of existing dry eye.

Differentially Expressed Gene Pathways in the Conjunctiva of Sjögren Syndrome Keratoconjunctivitis Sicca

Sjögren syndrome (SS) is an autoimmune condition that targets the salivary and lacrimal glands, with cardinal clinical signs of dry eye (keratoconjunctivitis sicca, KCS) and dry mouth. The conjunctiva of SS patients is often infiltrated by immune cells that participate in the induction and maintenance of local inflammation. The purpose of this study was to investigate immune-related molecular pathways activated in the conjunctiva of SS patients. Female SS patients (n=7) and controls (n=19) completed a series of oral, ocular surface exams. Symptom severity scores were evaluated using validated questionnaires (OSDI and SANDE). All patients fulfilled the ACR/EULAR criteria for SS and the criteria for KCS. Fluorescein and lissamine green dye staining evaluated tear-break-up time (TBUT), corneal and conjunctival disease, respectively. Impression cytology of the temporal bulbar conjunctiva was performed to collect cells lysed and subjected to gene expression analysis using the NanoString Immunology Panel. 53/594 differentially expressed genes (DEGs) were observed between SS and healthy controls; 49 DEGs were upregulated, and 4 were downregulated (TRAF5, TGFBI, KLRAP1, and CMKLRI). The top 10 DEGs in descending order were BST2, IFITM1, LAMP3, CXCL1, IL19, CFB, LY96, MX1, IL4R, CDKN1A. Twenty pathways had a global significance score greater or equal to 2. Spearman correlations showed that 29/49 upregulated DEGs correlated with either TBUT (inverse) or OSDI or conjunctival staining score (positive correlations). Venn diagrams identified that 26/29 DEGs correlated with TBUT, 5/26 DEGs correlated with OSDI, and 16/26 correlated with conjunctival staining scores. Five upregulated DEGs (CFB, CFI, IL1R1, IL2RG, IL4R) were uniquely negatively correlated with TBUT. These data indicate that the conjunctiva of SS patients exhibits a phenotype of immune activation, although some genes could be inhibitory. Some of the DEGs and pathways overlap with previous DEGs in salivary gland biopsies, but new DEGs were identified, and some of these correlated with symptoms and signs of dry eye. Our results indicate that gene analysis of conjunctiva imprints is a powerful tool to understand the pathogenesis of SS and develop new therapeutic targets.

Experimental Mouse Models of Ragweed- and Papain-Induced Allergic Conjunctivitis

Mouse models of allergic conjunctivitis mimic various aspects of human allergic conjunctivitis. They are useful as acute models of allergic conjunctivitis to study immunological aspects of this condition. In this chapter, we will describe ragweed-pollen-induced experimental allergic conjunctivitis (mostly driven by adaptive immunity), and papain-soaked contact lens-induced experimental allergic conjunctivitis (mostly driven by innate immunity). Giemsa staining of histological sections is used for quantification of the number of infiltrating eosinophils, which is useful to evaluate the severity of the allergic inflammation. Immunohistochemical staining and quantitative PCR are used to clarify spatiotemporal expression of proinflammatory molecules in the conjunctival tissue. Flow cytometric analysis of conjunctival tissue is used for the detection of innate lymphoid cell type 2 (ILC2) in the ocular surface tissues.

Inflammatory basis for dry eye disease flares

Most patients with chronic dry eye disease (DED) have episodic flares, which can be triggered by a variety of activities and environmental stresses. These flares are typically associated with rapid exacerbation of discomfort symptoms, followed by prolonged elevation of inflammation. In an acute flare, ocular surface inflammation begins with a nonspecific innate immune response, in some cases followed by a slower but more specific adaptive immune response. At the ocular surface, epithelial cells are central to the innate immune response, and we discuss their role in DED flares alongside the other core components. Epithelial cells and other cells of the innate response (neutrophils, monocytes, macrophages and dendritic cells) trigger flares in response to increased osmolarity, detected via pattern receptors on their cell surface. Ultimately, downstream signaling pathways activate innate and adaptive immune responses, with consequent inflammation and symptoms. In chronic DED, pathogenic T cells have infiltrated the ocular surface tissues. The established adaptive immune response is likely to lead to flare-ups at lower thresholds of stress, with inflammation maintained over a longer period. Increased understanding of the inflammatory cascades activated during a flare may guide management and improve outcomes.

Effect of IRT5 probiotics on dry eye in the experimental dry eye mouse model

Objective

To investigate the clinical effects of IRT5 probiotics in the environmental dry eye model.

Methods

Eight week old male C57BL/6 mice were randomly divided into two groups; control group (n = 16) received oral gavage of 300 μL phosphate-buffered saline (PBS) alone once daily, IRT5 group (n = 9) received oral gavage of 1 x 10⁹ CFU IRT5 probiotics powder in 300 μL PBS once daily, both groups for 11 to 12 days. Simultaneously, all mice underwent dry eye induction. Tear secretion, corneal staining and conjunctival goblet cell density were evaluated. Quantative real-time polymerase chain reaction (RT-PCR) for inflammation-related markers was performed. 16S ribosomal RNA of fecal microbiome was analyzed and compositional difference, alpha and beta diversities were assessed.

Results

There was no difference in NEI score but significant increase in tear secretion was observed in IRT5 group (p < 0.001). There was no significant difference in goblet cell density between groups. Quantative RT-PCR of cornea and conjunctiva revealed increased TNF-α expression in IRT5 group (p < 0.001) whereas other markers did not significantly differ from control. IRT5 group had significantly increased species diversity by Shannon index (p = 0.041). Beta diversity of genus by UniFrac principle coordinates analysis showed significant distance between groups (p = 0.001). Compositional differences between groups were observed and some were significantly associated with tear secretion. Multivariate linear regression analysis revealed Christensenellaceae (p = 0.009), Lactobacillus Helveticus group (p = 0.002) and PAC001797_s (p = 0.011) to strongly influence tear secretion.

Conclusion

In experimental dry eye model, IRT5 probiotics treatment partially improves experimental dry eye by increasing tear secretion which was associated with and influenced by the change in intestinal microbiome. Also, intestinal microbiome may affect the lacrimal gland through a different mechanism other than regulating inflammation.

Tropism, replication competence, and innate immune responses of the coronavirus SARS-CoV-2 in human respiratory tract and conjunctiva: an analysis in ex-vivo and in-vitro cultures

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019, causing a respiratory disease (coronavirus disease 2019, COVID-19) of varying severity in Wuhan, China, and subsequently leading to a pandemic. The transmissibility and pathogenesis of SARS-CoV-2 remain poorly understood. We evaluate its tissue and cellular tropism in human respiratory tract, conjunctiva, and innate immune responses in comparison with other coronavirus and influenza virus to provide insights into COVID-19 pathogenesis.

METHODS

We isolated SARS-CoV-2 from a patient with confirmed COVID-19, and compared virus tropism and replication competence with SARS-CoV, Middle East respiratory syndrome-associated coronavirus (MERS-CoV), and 2009 pandemic influenza H1N1 (H1N1pdm) in ex-vivo cultures of human bronchus (n=5) and lung (n=4). We assessed extrapulmonary infection using ex-vivo cultures of human conjunctiva (n=3) and in-vitro cultures of human colorectal adenocarcinoma cell lines. Innate immune responses and angiotensin-converting enzyme 2 expression were investigated in human alveolar epithelial cells and macrophages. In-vitro studies included the highly pathogenic avian influenza H5N1 virus (H5N1) and mock-infected cells as controls.

FINDINGS

SARS-CoV-2 infected ciliated, mucus-secreting, and club cells of bronchial epithelium, type 1 pneumocytes in the lung, and the conjunctival mucosa. In the bronchus, SARS-CoV-2 replication competence was similar to MERS-CoV, and higher than SARS-CoV, but lower than H1N1pdm. In the lung, SARS-CoV-2 replication was similar to SARS-CoV and H1N1pdm, but was lower than MERS-CoV. In conjunctiva, SARS-CoV-2 replication was greater than SARS-CoV. SARS-CoV-2 was a less potent inducer of proinflammatory cytokines than H5N1, H1N1pdm, or MERS-CoV.

INTERPRETATION

The conjunctival epithelium and conducting airways appear to be potential portals of infection for SARS-CoV-2. Both SARS-CoV and SARS-CoV-2 replicated similarly in the alveolar epithelium; SARS-CoV-2 replicated more extensively in the bronchus than SARS-CoV. These findings provide important insights into the transmissibility and pathogenesis of SARS-CoV-2 infection and differences with other respiratory pathogens.

FUNDING

US National Institute of Allergy and Infectious Diseases, University Grants Committee of Hong Kong Special Administrative Region, China; Health and Medical Research Fund, Food and Health Bureau, Government of Hong Kong Special Administrative Region, China.

Genomic foundations of evolution and ocular pathogenesis in human adenovirus species D

Human adenovirus commonly causes infections of respiratory, gastrointestinal, genitourinary, and ocular surface mucosae. Although most adenovirus eye infections are mild and self-limited, specific viruses within human adenovirus species D are associated with epidemic keratoconjunctivitis (EKC), a severe and highly contagious ocular surface infection, which can lead to chronic and/or recurrent, visually disabling keratitis. In this review, we discuss the links between adenovirus ontogeny, genomics, immune responses, and corneal pathogenesis, for those viruses that cause EKC.

Cluster of differentiation 30 expression in lacrimal gland and conjunctival tissues in patients with Sjögren's syndrome: Case series

INTRODUCTION

Sjögren's syndrome (SS) often causes lymphoproliferative disorders such as malignant lymphoma and macroglobrinemia. Approximately 5% of long-term follow-up SS patients develop malignant lymphoma. Recently, the tumor necrosis factor receptor superfamily cluster of differentiation 30 (CD30) has been thought to be implicated in malignant cells in organs affected by Hodgikin lymphoma or in a prognostic marker of diffuse large B cell lymphoma. In this study, we investigated CD30 expression in lacrimal gland and conjunctiva in patients with SS.

METHODS

We examined lacrimal gland and conjunctival tissues for the diagnosis from 3 female SS patients with a median age of 51 and 3 female chronic graft-versus-host disease (cGVHD) patients with a median age of 41. Histological analysis of these tissues of the remaining samples was conducted by methods including immunohistochemistry and electron microscopy (#20090277). We analyzed the expression and localization of cluster of differentiation 4 (CD4), cluster of differentiation 8 (CD8), cluster of differentiation 20 (CD20), CD30, and Interferon-γ in tissue sections prepared from lacrimal glands and conjunctiva in 3 each of SS and cGVHD patients.

RESULTS

There were more B cells and plasma cells in lobules of SS-affected lacrimal glands than in those of their cGVHD-affected counterparts. Interferon-γ was expressed on endothelia of capillaries in SS-affected lacrimal gland and conjunctival tissues whereas it was expressed on fibroblasts in their GVHD-affected equivalents. Furthermore, lacrimal glands and conjunctiva disordered by SS had a greater number of CD30 cells than those disordered by cGVHD.

CONCLUSION

Our results suggest that CD30 cells are increased in lacrimal glands and conjunctiva affected by SS and that a subset of SS patients are thereby at risk of development malignant lymphoma.

Distribution of Interleukin-22-secreting Immune Cells in Conjunctival Associated Lymphoid Tissue

PURPOSE

Interleukin (IL)-22 is a cytokine involved in epithelial cell regeneration. Currently, no research studies have analyzed the distribution of the three distinct IL-22-secreting cell populations in human or mouse conjunctiva. This study investigated the distribution of the three main populations of IL-22-secreting immune cells, αβ Th cells, γδ T cells, or innate cells (innate lymphoid cells [ILCs] or natural killer cells), in conjunctival associated lymphoid tissues (CALTs) in human and mouse models.

METHODS

We collected discarded cadaveric bulbar conjunctival tissue specimens after preservation of the corneo-limbal tissue for keratoplasty from four enucleated eyes of the domestic donor. The bulbar conjunctiva tissue, including the cornea from normal (n = 27) or abraded (n = 4) B6 mice, were excised and pooled in RPMI 1640 media. After the lymphoid cells were gated in forward and side scattering, the αβ Th cells, γδ T cells, or innate lymphoid cells were positively or negatively gated using anti-CD3, anti-γδ TCR, and anti-IL-22 antibodies, with a FACSCanto flow cytometer.

RESULTS

In normal human conjunctiva, the percentage and number of cells were highest in αβ Th cells, followed by γδ T cells and CD3- γδ TCR- IL-22+ innate cells (presumed ILCs, pILCs) (Kruskal-Wallis test, p = 0.012). In normal mice keratoconjunctiva, the percentage and total number were highest in γδ T cells, followed by αβ Th cells and pILCs (Kruskal-Wallis test, p = 0.0004); in corneal abraded mice, the population of αβ Th cells and pILCs tended to increase.

CONCLUSIONS

This study suggests that three distinctive populations of IL-22-secreting immune cells are present in CALTs of both humans and mice, and the proportions of IL-22+αβ Th cells, γδ T cells, and pILCs in CALTs in humans might be differently distributed from those in normal mice.

Conjunctival transcriptome profiling of Solomon Islanders with active trachoma in the absence of Chlamydia trachomatis infection

BACKGROUND

Clinical signs of active (inflammatory) trachoma are found in many children in the Solomon Islands, but the majority of these individuals have no serological evidence of previous infection with Chlamydia trachomatis. In Temotu and Rennell and Bellona provinces, ocular infections with C. trachomatis were seldom detected among children with active trachoma; a similar lack of association was seen between active trachoma and other common bacterial and viral causes of follicular conjunctivitis. Here, we set out to characterise patterns of gene expression at the conjunctivae of children in these provinces with and without clinical signs of trachomatous inflammation-follicular (TF) and C. trachomatis infection.

METHODS

Purified RNA from children with and without active trachoma was run on Affymetrix GeneChip Human Transcriptome Array 2.0 microarrays. Profiles were compared between individuals with ocular C. trachomatis infection and TF (group DI; n = 6), individuals with TF but no C. trachomatis infection (group D; n = 7), and individuals without TF or C. trachomatis infection (group N; n = 7). Differential gene expression and gene set enrichment for pathway membership were assessed.

RESULTS

Conjunctival gene expression profiles were more similar within-group than between-group. Principal components analysis indicated that the first and second principal components combined explained almost 50% of the variance in the dataset. When comparing the DI group to the N group, genes involved in T-cell proliferation, B-cell signalling and CD8+ T cell signalling pathways were differentially regulated. When comparing the DI group to the D group, CD8+ T-cell regulation, interferon-gamma and IL17 production pathways were enriched. Genes involved in RNA transcription and translation pathways were upregulated when comparing the D group to the N group.

CONCLUSIONS

Gene expression profiles in children in the Solomon Islands indicate immune responses consistent with bacterial infection when TF and C. trachomatis infection are concurrent. The transcriptomes of children with TF but without identified infection were not consistent with allergic or viral conjunctivitis.

Goblet cell loss abrogates ocular surface immune tolerance

Intestinal epithelial cells condition tolerogenic properties in DCs. Aqueous-deficient dry eye is associated with goblet cell (GC) loss and increased IFN-γ expression in the conjunctiva. We hypothesized that loss of GCs reduces tolerance-inducing properties of antigen presenting cells (APCs) in the conjunctiva and draining nodes. Mice lacking the SAM pointed domain containing ETS transcription factor (Spdef) that is required for GC differentiation had an increased frequency of macrophages in the conjunctiva and CD11b+CD11c+ DCs in the conjunctiva and draining nodes, and these cells had greater IL-12 expression than WT mice. Conditioned media from cultured WT conjunctival GCs suppressed LPS-induced IL-12 production by conjunctival APCs. OVA antigen-specific OTII CD4+ T cells primed by Spdef-KO draining lymph node APCs showed greater proliferation, lower frequency of Foxp3+, increased frequency of IFN-γ+ and IL-17+ cells, and greater IFN-γ production than those primed by WT APCs. The immune tolerance to OVA antigen topically applied to the conjunctiva measured by cutaneous delayed type hypersensitivity (DTH) reaction, OVA-specific T cell proliferation, Foxp3 induction, and IFN-γ production observed in WT mice was lost in the Spdef-KO mice. We concluded that conjunctival GCs condition tolerogenic properties in APCs that suppress IL-12 production and Th1 polarization.

Loss of Neurokinin-1 Receptor Alters Ocular Surface Homeostasis and Promotes an Early Development of Herpes Stromal Keratitis

Substance P neuropeptide and its receptor, neurokinin-1 receptor (NK1R), are reported to present on the ocular surface. In this study, mice lacking functional NK1R exhibited an excessive desquamation of apical corneal epithelial cells in association with an increased epithelial cell proliferation and increased epithelial cell density, but decreased epithelial cell size. The lack of NK1R also resulted in decreased density of corneal nerves, corneal epithelial dendritic cells (DCs), and a reduced volume of basal tears. Interestingly, massive accumulation of CD11c+CD11b+ conventional DCs was noted in the bulbar conjunctiva and near the limbal area of corneas from NK1R-/- mice. After ocular HSV-1 infection, the number of conventional DCs and neutrophils infiltrating the infected corneas was significantly higher in NK1R-/- than C57BL/6J mice. This was associated with an increased viral load in infected corneas of NK1R-/- mice. As a result, the number of IFN-γ-secreting virus-specific CD4 T cells in the draining lymph nodes of NK1R-/- mice was much higher than in infected C57BL/6J mice. An increased number of CD4 T cells and mature neutrophils (CD11b+Ly6ghigh) in the inflamed corneas of NK1R-/- mice was associated with an early development of severe herpes stromal keratitis. Collectively, our results show that the altered corneal biology of uninfected NK1R-/- mice along with an enhanced immunological response after ocular HSV-1 infection causes an early development of herpes stromal keratitis in NK1R-/- mice.

Immunohistochemical Analysis of Scarring Trachoma Indicates Infiltration by Natural Killer and Undefined CD45 Negative Cells

INTRODUCTION

The phenotype and function of immune cells infiltrating the conjunctiva in scarring trachoma have yet to be fully characterized. We assessed tissue morphology and immunophenotype of cellular infiltrates found in trachomatous scarring compared to control participants.

METHODOLOGY

Clinical assessments and conjunctival biopsy samples were obtained from 34 individuals with trachomatous scarring undergoing trichiasis surgery and 33 control subjects undergoing cataract or retinal detachment surgery. Biopsy samples were fixed in buffered formalin and embedded in paraffin wax. Hematoxylin and eosin (H&E) staining was performed for assessment of the inflammatory cell infiltrate. Immunohistochemical staining of single markers on individual sections was performed to identify cells expressing CD3 (T-cells), CD4 (helper T-cells), CD8 (suppressor/cytotoxic T-cells and Natural Killer, NK, cells), NCR1 (NK cells), CD20 (B-cells), CD45 (nucleated hematopoietic cells), CD56 (NK and T-cells), CD68 (macrophages/monocytes) and CD83 (mature dendritic cells). The degree of scarring was assessed histologically using cross-polarized light to visualize collagen fibres.

PRINCIPLE FINDINGS

Scarring, regardless of clinical inflammation, was associated with increased inflammatory cell infiltrates on H&E and CD45 staining. Scarring was also associated with increased CD8+ and CD56+ cells, but not CD3+ cells, suggestive of a NK cell infiltrate. This was supported by the presence of NCR1+ cells. There was some increase in CD20+ cells, but no evidence for increased CD4+, CD68+ or CD83+ cells. Numerous CD45 negative cells were also seen in the population of infiltrating inflammatory cells in scarred conjunctiva. Disorganization of the normal collagen architecture was strongly associated with clinical scarring.

CONCLUSIONS/SIGNIFICANCE

These data point to the infiltration of immune cells with a phenotype suggestive of NK cells in conjunctival trachomatous scarring. A large proportion of CD45 negative inflammatory cells were also present. Future work should seek to understand the stimuli leading to the recruitment of these cells and their role in progressive scarring.

Inverse relationship between microRNA-155 and -184 expression with increasing conjunctival inflammation during ocular Chlamydia trachomatis infection

BACKGROUND

Trachoma, a preventable blinding eye disease, is initiated by ocular infection with Chlamydia trachomatis (Ct). We previously showed that microRNAs (miR) -147b and miR-1285 were up-regulated in inflammatory trachomatous scarring. During the initial stage of disease, follicular trachoma with current Ct infection, the differential expression of miR has not yet been investigated.

METHODS

Conjunctival samples were collected from 163 children aged 1-9 years old living in a trachoma-endemic region of Guinea Bissau, West Africa. Small RNA sequencing (RNAseq) was carried out on samples from five children with follicular trachoma and current Ct infection and five children with healthy conjunctivae and no Ct infection. Small RNAseq was also carried out on human epithelial cell lines infected with ocular Ct strains A2497 and isogenic plasmid-free A2497 in vitro. Results were validated by quantitative PCR (qPCR) in 163 clinical samples.

RESULTS

Differential expression of RNAseq data identified 12 miR with changes in relative expression during follicular trachoma, of which 9 were confirmed as differentially expressed by qPCR (miR-155, miR-150, miR-142, miR-181b, miR-181a, miR-342, miR-132, miR-4728 and miR-184). MiR-155 and miR-184 expression had a direct relationship with the degree of clinical inflammation. MiR-155 was up-regulated (OR = 2.533 ((95 % CI = 1.291-4.971); P = 0.0069) and miR-184 was down-regulated (OR = 0.416 ((95 % CI = 0.300-0.578); P = 1.61*10(-7)) as the severity of clinical inflammation increased. Differential miR expression was not detected in HEp-2 or HCjE epithelial cells 48 h post infection with Ct in vitro. HCjE cells, a conjunctival epithelial cell line, had a markedly different miR background expression compared to HEp-2 cells.

CONCLUSIONS

In follicular trachoma, expression of miR-155 and miR-184 is correlated with the severity of inflammation. This likely reflects host regulation of the immune response and a prolonged period of wound healing following the clearance of Ct. Prolonged healing may be associated with subsequent development of scarring trachoma.

Dynamic change in natural killer cell type in the human ocular mucosa in situ as means of immune evasion by adenovirus infection

The most severe form of virus-induced inflammation at the ocular surface is epidemic keratoconjunctivitis (EKC), often caused by group D human adenoviruses (HAdVs). We investigated the dynamics and mechanisms of changes in natural killer (NK) cell types in the human ocular mucosal surface in situ over the course of infection. In the acute phase of infection, the mature CD56(dim)NK cells that comprise a major subpopulation in the normal human conjunctiva are replaced by CD56(bright)NK cells recruited to the ocular surface by chemokines produced by the infected epithelium, and NKG2A-expressing CD56(dim) and CD56(bright) NK cells become the major subpopulations in severe inflammation. These NK cells attracted to the mucosal surface are however incapable of mounting a strong antiviral response because of upregulation of the inhibitory ligand human leukocyte antigen-E (HLA-E) on infected epithelium. Furthermore, group D HAdVs downregulate ligands for activating NK cell receptors, thus rendering even the mature NKG2A(-)NK cells unresponsive, an immune-escape mechanism distinct from other adenoviruses. Our findings imply that the EKC-causing group D HAdVs utilize these multiple pathways to inhibit antiviral NK cell responses in the initial stages of the infection.

Delivery of a Chlamydial Adhesin N-PmpC Subunit Vaccine to the Ocular Mucosa Using Particulate Carriers

Trachoma, caused by the intracellular bacterium Chlamydia trachomatis (Ct), remains the world's leading preventable infectious cause of blindness. Recent attempts to develop effective vaccines rely on modified chlamydial antigen delivery platforms. As the mechanisms engaged in the pathology of the disease are not fully understood, designing a subunit vaccine specific to chlamydial antigens could improve safety for human use. We propose the delivery of chlamydia-specific antigens to the ocular mucosa using particulate carriers, bacterial ghosts (BGs). We therefore characterized humoral and cellular immune responses after conjunctival and subcutaneous immunization with a N-terminal portion (amino acid 1-893) of the chlamydial polymorphic membrane protein C (PmpC) of Ct serovar B, expressed in probiotic Escherichia coli Nissle 1917 bacterial ghosts (EcN BGs) in BALB/c mice. Three immunizations were performed at two-week intervals, and the immune responses were evaluated two weeks after the final immunization in mice. In a guinea pig model of ocular infection animals were immunized in the same manner as the mice, and protection against challenge was assessed two weeks after the last immunization. N-PmpC was successfully expressed within BGs and delivery to the ocular mucosa was well tolerated without signs of inflammation. N-PmpC-specific mucosal IgA levels in tears yielded significantly increased levels in the group immunized via the conjunctiva compared with the subcutaneously immunized mice. Immunization with N-PmpC EcN BGs via both immunization routes prompted the establishment of an N-PmpC-specific IFNγ immune response. Immunization via the conjunctiva resulted in a decrease in intensity of the transitional inflammatory reaction in conjunctiva of challenged guinea pigs compared with subcutaneously and non-immunized animals. The delivery of the chlamydial subunit vaccine to the ocular mucosa using a particulate carrier, such as BGs, induced both humoral and cellular immune responses. Further investigations are needed to improve the immunization scheme and dosage.

Rabbit conjunctivae edema and release of NO, TNF-α, and IL-1β from macrophages induced by fractions and esculentosides isolated from Phytolacca americana

CONTEXT

The roots of Phytolacca americana L. (Phytolaccaceae) may be toxic. Despite heated controversy over the toxic compounds of P. americana, especially esculentosides, relevant studies remain scarce.

OBJECTIVE

The objective of this study is to screen the toxic fractions and compounds of P. americana, to determine the controlling indices, and to provide evidence for unraveling the mechanism.

MATERIALS AND METHODS

Petroleum ether (PE), CH2Cl2, n-BuOH, and water fractions were isolated from 70% ethanol extract of P. americana. The n-BuOH fraction was dissolved in 50% ethanol and precipitated by adding ethyl ether. The resultant supernatants and precipitates were referred to as SUPs and SEDs fractions, respectively. SUPs fraction was separated by column chromatography into four main stimulating esculentosides that were identified by HR-ESI/MS and NMR as EsA, EsB, EsC, and EsF. The irritating effects of esculentosides on rabbit conjunctivae (500 μg/eye) was observed by pathological examination and those on macrophages (5, 25, 50 and 100 μg/mL) were evaluated by detecting changes of NO, TNF-α, and IL-1β levels.

RESULTS AND DISCUSSION

n-BuOH, SUP fractions, and EsC induced severe conjunctival edema. The four esculentosides induced dose-dependent releases of proinflammatory mediators NO, TNF-α, and IL-1β from macrophages, and releasing amounts peaked after 2 h of treatment. EsC and EsF induced macrophages to release mediators most significantly. EsC (50 μg/mL) functioned more effectively than EsF did, and similarly n-BuOH and SUPs fractions functioned more effectively than the esculentoside mixture. Thus, the four esculentosides exerted proinflammatory effects synergistically.

CONCLUSION

All extracted esculentosides, especially EsC, induced inflammatory stimulation. Phytolacca americana-induced irritation of the gastrointestinal tract may be associated with esculentosides such as EsC.

Efficacy of epinastine hydrochloride ophthalmic solution in allergic conjunctivitis by conjunctival cedar pollen allergen challenge

BACKGROUND

Epinastine hydrochloride is a selective histamine H1 receptor antagonist that also inhibits IgE receptor-mediated histamine release from mast cells.

OBJECTIVE

To show the superiority of epinastine 0.05% ophthalmic solution (epinastine) to placebo ophthalmic solution (placebo) and noninferiority to olopatadine 0.1% ophthalmic solution (olopatadine) for cedar pollen antigen-induced ocular itching and conjunctival hyperemia.

METHODS

The study was conducted in ophthalmologically asymptomatic adult volunteers with seasonal allergic conjunctivitis using a conjunctival allergen challenge test. Subjects were randomized into 3 groups (n = 87) to evaluate superiority to placebo (visits 4 to 6) and 2 groups (n = 86) to evaluate noninferiority to olopatadine (visit 7). At each visit, a single administration of the study medication was instilled at 15 minutes (visit 4), 4 hours (visit 5), 8 hours (visit 6), and 4 hours (visit 7) before the conjunctival allergen challenge test. Ocular itching and conjunctival hyperemia of allergic conjunctivitis were assessed after the conjunctival allergen challenge test.

RESULTS

For the primary end point, epinastine showed superiority to placebo for the inhibition of ocular itching and conjunctival hyperemia induced at 4 hours after the dose (equivalent to 4-times-daily dosing). For the secondary end points, epinastine significantly inhibited itching and conjunctival hyperemia induced at 15 minutes and 8 hours after the dose (equivalent to 2-times-daily dosing) compared with placebo. In addition, epinastine demonstrated noninferiority to olopatadine for ocular itching and conjunctival hyperemia. No adverse drug reactions or serious adverse events were reported throughout the study, indicating that epinastine has a good safety profile.

CONCLUSION

Epinastine is effective and safe for the treatment of allergic conjunctivitis.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT01363700.

Tetranychus urticae allergy in a population without occupational exposure

BACKGROUND

Tetranychus urticae is a phytophagus mite found in the leaves of numerous plants. High sensitization rates have been demonstrated, however, provocation tests have only been performed in an occupational setting.

OBJECTIVE

To assess accuracy of skin prick tests and clinical relevance of T. urticae sensitization by means of conjunctival provocation tests (CPT) in a population without occupational exposure and to evaluate possible environmental risk factors for T. urticae allergy.

METHODS

Patients ≥ 18 years old sensitized to T. urticae (n = 12) and a non-sensitized control group (n = 12) were invited to perform CPT with T. urticae and fulfill a questionnaire including demographic data, questions on environmental exposure to T. urticae and allergy symptoms/diagnosis. A single-blinded placebo-controlled CPT with T. urticae (Leti®) was performed with increasing concentrations (0.002, 0.02, 0.2 and 2 mg/mL) and considered positive if conjunctival hyperemia, palpebral edema or lacrimation were observed in the tested eye.

RESULTS

Of T. urticae sensitized patients (mean wheal 4.4 ± 1.5 mm), 9 had a positive CPT, including 3 monosensitized. A good diagnostic accuracy was found for skin prick tests: AUC = 0.952, sensitivity = 100%, specificity = 80%, positive likelihood ratio = 5 and negative likelihood ratio = 0 for a 3 mm wheal. No differences were found between allergic and non-allergic subjects regarding atopy, allergic disease or farming activities.

CONCLUSIONS

A high prevalence of allergy to Tetranychus urticae was found in the north of Portugal. Future studies with a larger number of patients are needed to evaluate its relation to clinical symptoms and the impact of environmental factors.

Oleanolic acid controls allergic and inflammatory responses in experimental allergic conjunctivitis

Pollen is the most common aeroallergen to cause seasonal conjunctivitis. The result of allergen exposure is a strong Th2-mediated response along with conjunctival mast cell degranulation and eosinophilic infiltration. Oleanolic acid (OA) is natural a triterpene that displays strong anti-inflammatory and immunomodulatory properties being an active anti-allergic molecule on hypersensitivity reaction models. However, its effect on inflammatory ocular disorders including conjunctivitis, has not yet been addressed. Hence, using a Ragweed pollen (RWP)-specific allergic conjunctivitis (EAC) mouse model we study here whether OA could modify responses associated to allergic processes. We found that OA treatment restricted mast cell degranulation and infiltration of eosinophils in conjunctival tissue and decreased allergen-specific Igs levels in EAC mice. Th2-type cytokines, secreted phospholipase A2 type-IIA (sPLA2-IIA), and chemokines levels were also significantly diminished in the conjunctiva and serum of OA-treated EAC mice. Moreover, OA treatment also suppressed RWP-specific T-cell proliferation. In vitro studies, on relevant cells of the allergic process, revealed that OA reduced the proliferative and migratory response, as well as the synthesis of proinflammatory mediators on EoL-1 eosinophils and RBL-2H3 mast cells exposed to allergic and/or crucial inflammatory stimuli such as RWP, sPLA2-IIA or eotaxin. Taken together, these findings demonstrate the beneficial activity of OA in ocular allergic processes and may provide a new intervention strategy and potential therapy for allergic diseases.

Conjunctival scarring in trachoma is associated with the HLA-C ligand of KIR and is exacerbated by heterozygosity at KIR2DL2/KIR2DL3

BACKGROUND

Chlamydia trachomatis is globally the predominant infectious cause of blindness and one of the most common bacterial causes of sexually transmitted infection. Infections of the conjunctiva cause the blinding disease trachoma, an immuno-pathological disease that is characterised by chronic conjunctival inflammation and fibrosis. The polymorphic Killer-cell Immunoglobulin-like Receptors (KIR) are found on Natural Killer cells and have co-evolved with the Human Leucocyte Antigen (HLA) class I system. Certain genetic constellations of KIR and HLA class I polymorphisms are associated with a number of diseases in which modulation of the innate responses to viral and intracellular bacterial pathogens is central.

METHODOLOGY

A sample of 134 Gambian pedigrees selected to contain at least one individual with conjunctival scarring in the F1 generation was used. Individuals (n = 830) were genotyped for HLA class I and KIR gene families. Family Based Association Tests and Case Pseudo-control tests were used to extend tests for transmission disequilibrium to take full advantage of the family design, genetic model and phenotype.

PRINCIPLE FINDINGS

We found that the odds of trachomatous scarring increased with the number of genome copies of HLA-C2 (C1/C2 OR = 2.29 BHP-value = 0.006; C2/C2 OR = 3.97 BHP-value = 0.0004) and further increased when both KIR2DL2 and KIR2DL3 (C2/C2 OR = 5.95 BHP-value = 0.006) were present.

CONCLUSIONS

To explain the observations in the context of chlamydial infection and trachoma we propose a two-stage model of response and disease that balances the cytolytic response of KIR expressing NK cells with the ability to secrete interferon gamma, a combination that may cause pathology. The data presented indicate that HLA-C genotypes are important determinants of conjunctival scarring in trachoma and that KIR2DL2/KIR2DL3 heterozygosity further increases risk of conjunctival scarring in individuals carrying HLA-C2.

Clinical measurement of eosinophil numbers in eosinophilic conjunctivitis

Cytological examination of conjunctival scrapings is a valuable technique in differentiating various types of conjunctivitis. Brush conjunctival cytology is easy to use, and it may show a rich cell sample also from the deeper conjunctival layers. It is atraumatic and suitable for tarsal conjunctival cytology. The Papanicolaou staining can be used for examination of epithelial cells and inflammatory cells. The semiquantitative counting method is rapid to use and gives some information about the severity and nature of the inflammation. Our modified method identifies the presence of eosinophils which are the hallmark both in allergic conjunctivitis and in non-allergic eosinophilic conjunctivitis (NAEC). NAEC is quite common affecting in most cases middle-aged or older people with the majority being women. NAEC is often connected with dry eye which in many cases can be seen in conjunctival cytology.

Dendritic cell-derived thrombospondin-1 is critical for the generation of the ocular surface Th17 response to desiccating stress

TSP-1 is a physiologic activator of TGF-β, a critical induction factor for Th17-mediated immunity. The purpose of this study was to investigate the role of TSP-1 in the induction of the Th17 ocular surface response to DS. TSP-1KO and WT mice were subjected to DS5 and DS10), and parameters of ocular surface disease, including corneal barrier function, conjunctival CD4(+) T cell infiltration, and GC density, were evaluated. TSP-1KO mice subjected to DS had less corneal barrier disruption, reduced loss of PAS+ GC, and decreased CD4(+) T cell infiltration in the conjunctiva. In contrast to WT, TSP-1KO mice failed to up-regulate MMP-3 and MMP-9 mRNA transcripts in the cornea and IL-17A mRNA transcripts in the conjunctiva. RAG-1KO recipients of adoptively transferred CD4(+) T cells isolated from TSP-1KO mice subjected to DS5 showed milder dry-eye phenotype and less conjunctival inflammation than recipients of CD4(+) T cells from DS5 WT control. Reconstitution of TSP-1KO mice with WT DCs prior to DS reversed the resistance of the TSP-1KO to DS-induced immunopathology. In conclusion, DC-derived TSP-1 is critical for generating the Th17 ocular surface response to DS.

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.

The ocular surface: from physiology to the ocular allergic diseases

Allergic conjunctivitis (AC) is an inflammation of the conjunctiva secondary to an immune response to exogenous antigens, usually called allergens. In fact, AC is a syndrome that involves the entire ocular surface, including conjunctiva, lids, cornea, and tear film. The signs and symptoms of AC have a meaningful effect on comfort and patient health, and could be influenced by environment, genetics and immune regulation mechanisms, all of which work together in a complex immunological homeostasis. Dysregulation in such immune responses could turn into a variety of ocular allergic diseases (OAD). This review describes some of the current understanding of cellular and molecular pathways involved in different OAD.

Staphylococcus aureus activates the NLRP3 inflammasome in human and rat conjunctival goblet cells

The conjunctiva is a moist mucosal membrane that is constantly exposed to an array of potential pathogens and triggers of inflammation. The NACHT, leucine rich repeat (LRR), and pyrin domain-containing protein 3 (NLRP3) is a Nod-like receptor that can sense pathogens or other triggers, and is highly expressed in wet mucosal membranes. NLRP3 is a member of the multi-protein complex termed the NLRP3 inflammasome that activates the caspase 1 pathway, inducing the secretion of biologically active IL-1β, a major initiator and promoter of inflammation. The purpose of this study was to: (1) determine whether NLRP3 is expressed in the conjunctiva and (2) determine whether goblet cells specifically contribute to innate mediated inflammation via secretion of IL-1β. We report that the receptors known to be involved in the priming and activation of the NLRP3 inflammasome, the purinergic receptors P2X4 and P2X7 and the bacterial Toll-like receptor 2 are present and functional in conjunctival goblet cells. Toxin-containing Staphylococcus aureus (S. aureus), which activates the NLRP3 inflammasome, increased the expression of the inflammasome proteins NLRP3, ASC and pro- and mature caspase 1 in conjunctival goblet cells. The biologically active form of IL-1β was detected in goblet cell culture supernatants in response to S. aureus, which was reduced when the cells were treated with the caspase 1 inhibitor Z-YVAD. We conclude that the NLRP3 inflammasome components are present in conjunctival goblet cells. The NRLP3 inflammasome appears to be activated in conjunctival goblet cells by toxin-containing S. aureus via the caspase 1 pathway to secrete mature IL1-β. Thus goblet cells contribute to the innate immune response in the conjunctiva by activation of the NLRP3 inflammasome.

The role of inflammation in the progression of ocular surface damage in children following allogeneic haematopoietic cell transplantation

The aim of the study was to evaluate HLA-DR expression and cellular morphology of the conjunctival epithelium cells in children who underwent haematopoietic cell transplantation, and to assess the relation between HLA-DR expression and cellular morphology. Impression cytology with staining was used to visualize epithelium cells, whereas immunohistochemistry was applied to assess HLA-DR expression. Elevated HLA-DR expression and increased cytological abnormalities were observed in the study group when compared to the controls. An increase in HLA-DR expression was accompanied by a decrease in the number of eyes with normal epithelium morphology together with the increase in squamous metaplasia features. We can conclude that inflammation of conjunctiva can follow stem cell allotransplantation. Ocular surface inflammation may lead to squamous metaplasia of the conjunctiva.

The dominant human conjunctival epithelial CD8αβ+ T cell population is maintained with age but the number of CD4+ T cells increases

The conjunctiva is a highly specialized ocular mucosal surface that, like other mucosa, houses a number of leukocyte populations. These leukocytes have been implicated in age-related inflammatory diseases such as dry-eye, but their phenotypic characteristics remain largely undetermined. Existing literature provides rudimentary data from predominantly immunohistochemical analyses of tissue sections, prohibiting detailed and longitudinal examination of these cells in health and disease. Using recovered cells from ocular surface impression cytology and flow cytometry, we examined the frequency of leukocyte subsets in human conjunctival epithelium and how this alters with age. Of the total CD45+ leukocyte population within the conjunctival epithelium, 87% [32-99] (median) [range] comprised lymphocytes, with 69% [47-90] identified as CD3 + CD56- T cells. In contrast to peripheral blood, the dominant conjunctival epithelial population was TCRαβ + CD8αβ + (80% [37-100]) with only 10% [0-56%] CD4+ cells. Whilst a significant increase in the CD4+ population was seen with age (r = 0.5; p < 0.01) the CD8+ population remained unchanged, resulting in an increase in the CD4:CD8 ratio (r = 0.5;p < 0.01). IFNγ expression was detectable in 18% [14-48] of conjunctival CD4+ T cells and this was significantly higher among older individuals (<35 years, 7[4-39] vs. >65 years, 43[20-145]; p < 0.05). The elevation of CD4+ cells highlights a potentially important age-related alteration in the conjunctival intra-epithelial leukocyte population, which may account for the vulnerability of the aging ocular surface to disease.

Evaluation of eosinophilic inflammation in a novel murine atopic keratoconjunctivitis model induced by crude Dermatophagoides farinae antigen

BACKGROUND

The purpose of this study is to conduct a histopathological research of the conjunctival findings and eosinophilic inflammation of novel atopic keratoconjunctivitis in a NC/Nga mouse model using crude Dermatophagoides farina.

METHODS

NC/Nga mice were sensitized by repeated topical applications of an ointment containing Dermatophagoides farinae body (Dfb). They were then divided into 4 groups depending on the following topical ophthalmic treatment: DFb group undergoing topical ophthalmic ointment containing Dfb; DFco group undergoing topical instillation of allergen extracts of Dermatophagoides farinae; Ba group undergoing topical ointment with substrate alone and NT group without after-topical ophthalmic treatment. At 24 hours after the last ophthalmic treatment, histopathological examination was performed. The density of the subepithelial infiltration of the eosinophils was determined. Serum total IgE and house-dust-mite (HDM)-specific IgE antibody concentrations were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

In the DFb group, the conjunctiva showed similar findings to those of atopic keratoconjunctivitis, i.e. intraepithelial pseudotubular formation, Torus-form infiltration due to massive lymphocytes in the palpebral conjunctiva and gelatinous hyperplasia in the limbus with subepithelial granuloma composed of lymphocytes and eosinophils. Subepithelial infiltration of eosinophil density in the DFb group [878.4 ± 399.7cells/mm2 (mean ± SD)] was significantly higher than in the other 2 groups (DFco 85.6 ± 40.1 Ba 49.2 ± 32.3) (P < 0.001). Total serum IgE concentration and HDM-specific serum IgE antibody concentration in the DFb group and the DFco group were significantly higher compared with those in the NT group.

CONCLUSIONS

Topical application of an ointment containing DFb to both the skin and eyes of NC/Nga mice can induce an atopic keratoconjunctivitis (AKC) model in these mice.

Conjunctiva-associated lymphoid tissue in avian mucosal immunity

Conjunctiva-associated lymphoid tissue's (CALT) role in generating avian mucosal adaptive immunity was measured by analyzing cellular composition, expression of the polymeric immunoglobulin receptor (pIgR), and production of cytokines and antibodies in chickens ocular exposed to a replication-deficient adenovirus of serotype 5 (Ad5). These studies demonstrate that CALT contains B cells, γδ T cells, T helper, and cytotoxic T cells, and a T lymphocyte composition, which more resembles Harderian glands than spleen. CALT-derived lymphocytes contain antigen-specific, IgA-secreting plasma cells and cytokine-producing lymphocytes after ocular Ad5 vaccination. The expression of the pIgR in the CALT's lymphoepithelium emphasizes the importance of mucosal immune protection by paraocular lymphoid tissues. The CALT immune response after ocular Ad5 boosting was influenced by prior high dose in ovo Ad5 priming. Thus, both mucosal and systemic immunization influenced Ad5-induced IFN-γ responses in CALT.

Capacities of migrating CD1b+ lymph dendritic cells to present Salmonella antigens to naive T cells

Dendritic cells (DCs) are well known as professional antigen-presenting cells (APC) able to initiate specific T-cell responses to pathogens in lymph nodes (LN) draining the site of infection. However, the respective contribution of migratory and LN-resident DCs in this process remains unclear. As DC subsets represent important targets for vaccination strategies, more precise knowledge of DC subsets able to present vaccine antigens to T cells efficiently is required. To investigate the capacities of DCs migrating in the lymph (L-DCs) to initiate a specific T-cell response, we used physiologically generated DCs collected from a pseudoafferent lymphatic cannulation model in sheep. The CD1b⁺ L-DCs were assessed for presenting antigens from the vaccine attenuated strain of Salmonella enterica serovar Abortusovis. CD1b⁺ L-DCs were able to phagocytose, process and to present efficiently Salmonella antigens to effector/memory T cells in vitro. They were shown to be efficient APC for the priming of allogeneic naive T cells associated with inducing both IFN-γ and IL-4 responses. They were also efficient in presenting Salmonella antigens to autologous naive T cells associated with inducing both IFN-γ and IL-10 responses. The capacities of L-DCs to process and present Salmonella antigens to T cells were investigated in vivo after conjunctival inoculation of Salmonella. The CD1b⁺ L-DCs collected after inoculation were able to induce the proliferative response of CD4⁺ T cells suggesting the in vivo capture of Salmonella antigens by the CD1b⁺ L-DCs, and their potential to present them directly to CD4⁺ T cells. In this study, CD1b⁺ L-DCs present potential characteristics of APC to initiate by themselves T cell priming in the LN. They could be used as target cells for driving immune activation in vaccinal strategies.

Transconjunctival immunotherapy using cholera toxin B to treat experimental allergic conjunctivitis in a mouse model

PURPOSE

We evaluated the use of immunological biomarkers in transconjunctival immunotherapy by using cholera toxin B for treating experimental allergic conjunctivitis in a mouse model.

METHODS

Balb/c mice were sensitized using intraperitoneal injections of ovalbumin (OVA) and were then divided into two groups. The first group was treated by topical instillation of OVA after the instillation of combined OVA and cholera toxin B (CTB) solution B group). The second group was treated by topical instillation of OVA alone (allergy group). The control group consisted of nonsensitized mice undergoing topical OVA instillation only. The numbers of eosinophils and CD4-positive lymphocytes in the conjunctiva were determined histologically, and the observation of immunoglobulin A (IgA)-positive cells in the conjunctiva was performed by immunohistochemistry. Cytokine concentration in the conjunctiva was determined by the protein-array methods. Messenger RNA expression of T-cell-specific markers, such as T-bet, GATA-3, and Foxp3, in the conjunctiva was detected by reversed transcriptase polymerase chain reaction.

RESULTS

The number of eosinophils and CD4-positive lymphocytes increased significantly in the allergy group compared with the control group (P < 0.001) but showed no difference between the CTB group and control group. Concentrations of interleukin 4 (IL-4) (P < 0.05), B-lymphocyte chemoattractant (P < 0.01), and thymus-expressed chemokine (P < 0.05) in the conjunctiva were significantly higher in the CTB group than in the other two groups. GATA-3 messenger RNA (mRNA) in the conjunctiva was expressed in the three groups, but T-bet and Foxp3 were not detected.

CONCLUSION

Transconjunctival immunotherapy using CTB can be evaluated by histological examination of eosinophils and CD4-positive T cells, and a mucosal immunity-associated chemokine and a helper T-cell-17-associated chemokine as biomarkers.

Randomized, double-blind, placebo-controlled clinical trial of sublingual immunotherapy in natural rubber latex allergic patients

BACKGROUND

Natural rubber latex allergy is a common and unsolved health problem. Since the avoidance of exposure is very difficult, immunotherapy is strongly recommended, but before its use in patients, it is essential to prove the efficacy and safety of extracts.The aim of the present randomised, double-blind, placebo-controlled clinical trial was to assess the efficacy and tolerability of latex sublingual immunotherapy in adult patients undergoing permanent latex avoidance.

METHODS

Twenty-eight adult latex-allergic patients (5 males and 23 females), with mean age of 39 years (range 24-57) were randomized to receive a commercial latex-sublingual immunotherapy or placebo during one year, followed by another year of open, active therapy. The following outcomes were measured at baseline and at the end of first and second year of follow-up: skin prick test, gloves-use score, conjunctival challenge test, total and specific IgE, basophil activation test, and adverse reactions monitoring.

RESULTS

No significant difference in any of the efficacy in vivo variables was observed between active and placebo groups at the end of the placebo-controlled phase, nor when each group was compared with their baseline values at the end of the two year-study. An improvement in the average percentage of basophils activated was observed. During the induction phase, 4 reactions in the active group and 5 in the placebo group were recorded. During the maintenance phase, two patients dropped out due to pruritus and to acute dermatitis respectively.

CONCLUSION

Further studies are needed to evaluate latex-sublingual immunotherapy, since efficacy could not be demonstrated in adult patients with avoidance of the allergen.

TRIAL REGISTRATION NUMBER

ACTRN12611000543987.

The role of histamine in ocular allergy

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

Contribution of IPS-1 to polyI:C-induced cytokine production in conjunctival epithelial cells

We previously demonstrated that ocular surface epithelium expressed TLR3 and that its ligand, polyI:C, stimulation induced the secretion of inflammatory cytokines and type I IFN. It was recently reported that RIG-I and MDA5 also recognize viral dsRNA mimicking polyI:C. In this study, we investigated whether RIG-I and/or MDA5 contribute to polyI:C-inducible responses in conjunctival epithelium. The expression of RIG-I, MDA5, and TLR3 in human conjunctival epithelium was examined by RT-PCR and their up-regulation after polyI:C stimulation by quantitative RT-PCR and immunoblot analysis. Human conjunctival epithelial cells also expressed RIG-I, MDA5 and TLR3 mRNA and protein. The expression of RIG-I and MDA5, but not of TLR3, was markedly up-regulated upon polyI:C stimulation. We also examined the function of IPS-1 (an adaptor molecule common to RIG-I and/or MDA5) and TLR3 in conjunctival epithelium using IPS-1 KO and TLR3 KO mice. To analyze in vivo murine conjunctival epithelial cells, 10 μl of a 100 μg/ml polyI:C solution were delivered subconjunctivally and as eye drops, then conjunctival epithelial cells were subjected to gene expression analysis. We focused on 10 transcripts up-regulated in murine conjunctival epithelium upon polyI:C stimulation. Cxcl10, Mx1, Ifi44, Ifi203, Iigp2 and Rtp4 were dominantly regulated by IPS-1, Ccl5 by TLR3, and Rsad2, Mx2 and Cmpk2 were regulated by TLR3 and IPS-1. Our results showed that conjunctival epithelial cells express RIG-I and MDA5, and IPS-1, an adaptor molecule common to RIG-I and MDA5, contributes to polyI:C-inducible cytokine production in conjunctival epithelial cells.

[TLR9 and HBD-2 gene expression by conjunctival and corneal cells in children with dendriform herpetic keratitis]

The current views of the role of innate immunity in protecting the organ of vision from viral infection offer scope for a search for new approaches to diagnosing and treating viral keratitis. TLR9 and HBD-2 gene expression in the conjunctiva and cornea was studied in children with dendriform herpetic keratitis. The latter showed a significant (more than 20-fold) increase in TLR9 gene expression as compared in healthy children. Conventional antiviral therapy for herpetic keratitis resulted in a significant decrease in the level of TLR9 gene expression (by more than two orders of magnitude). The use of the immunomodulator Superlymph in complex treatment normalized the level of TLR9 gene expression in the conjunctiva and cornea; moreover, there was a rapid relief of inflammation signs, an increase in visual acuity, and a reduction in the duration of treatment in patients with herpetic keratitis.

Antimicrobial peptides as a major part of the innate immune defense at the ocular surface

The ocular surface is in constant contact with the environment (e.g. when using one's fingers to insert a contact lens) and thus also with diverse bacteria, bacterial components and their pathogen associated molecules. Dysfunctions of the tear film structure or decreased moistening of the ocular surface, as in dry eye (keratoconjunctivitis sicca) for example, often lead to inflammatory and infectious complications resulting in severe functional disorders, particularly concerning the cornea. Besides different protective antimicrobial substances in the tear fluid (mucins, lysozyme, lactoferrin), the epithelia of cornea and conjunctiva can also protect themselves from microbial invasion by producing an arsenal of antimicrobial peptides (AMPs). A number of different studies have revealed that small cationic AMPs, which display antimicrobial activity against a broad spectrum of microorganisms, are a major component of the innate immune system at the human ocular surface. Furthermore, several AMPs modulate cellular activation processes like migration, proliferation, chemotaxis and cytokine production, and in this way also affect the adaptive immune system. In this article, we have summarized current knowledge of the mechanisms of activity and functional roles of AMPs, with a focus on potential multifunctional roles of human beta-defensins and S100 peptide psoriasin (S100A7) at the ocular surface.

Regulation of the inflammatory component in chronic dry eye disease by the eye-associated lymphoid tissue (EALT)

PURPOSE

The physiologically protective mucosal immune system of the ocular surface consists of lymphocytes, accessory leukocytes and soluble immune modulators. Their involvement has also been observed in inflammatory ocular surface diseases, including dry eye syndrome, and we have attempted here to describe their interaction.

METHODS

Our own results regarding the mucosal immune system of the human ocular surface are discussed together with the available literature on mucosal immunity and inflammatory ocular surface disease.

RESULTS

The mucosa of the ocular surface proper (conjunctiva and cornea) is anatomically continuous with its mucosal adnexa (the lacrimal gland and lacrimal drainage system) and contains a mucosal immune system termed 'eye-associated lymphoid tissue' (EALT). This extends from the periacinar lacrimal-gland-associated lymphoid tissue along the excretory ducts into the conjunctiva-associated lymphoid tissue (CALT) and further into the lacrimal drainage-associated lymphoid tissue (LDALT). EALT consists of continuous diffuse lymphoid effector tissue and of interspersed follicles for effector cell generation in CALT and LDALT. Typical events in ocular surface disease include alteration and activation of epithelial cells with loss of epithelial integrity, production of inflammatory cytokines, and potential presentation of non-pathogenic and self-antigens - leading to a loss of immune tolerance. Events in the deregulation of physiologically protective EALT, resulting vicious circles, and eventual self-propagating immunomodulated inflammatory disease processes are explained, discussed and visualized by schematic drawings.

CONCLUSION

Deregulation of EALT can orchestrate a self-propagating inflammatory mucosal disease process if the capacity of natural compensatory factors is overridden and if the disease is not limited by timely diagnosis and therapy.

A novel HLA (HLA-A*0201) transgenic rabbit model for preclinical evaluation of human CD8+ T cell epitope-based vaccines against ocular herpes

We introduced a novel humanized HLA-A*0201 transgenic (HLA Tg) rabbit model to assess the protective efficacy of a human CD8(+) T cell epitope-based vaccine against primary ocular herpes infection and disease. Each of the three immunodominant human CD8(+) T cell peptide epitopes from HSV-1 glycoprotein D (gD(53-61), gD(70-78), and gD(278-286)) were joined with a promiscuous human CD4(+) T cell peptide epitope (gD(49-82)) to construct three separate pairs of CD4-CD8 peptides. Each CD4-CD8 peptide pair was then covalently linked to an N(epsilon)-palmitoyl-lysine residue via a functional base lysine amino group to construct CD4-CD8 lipopeptides. HLA Tg rabbits were immunized s.c. with a mixture of the three CD4-CD8 HSV-1 gD lipopeptides. The HSV-gD-specific T cell responses induced by the mixture of CD4-CD8 lipopeptide vaccine and the protective efficacy against acute virus replication and ocular disease were determined. Immunization induced HSV-gD(49-82)-specific CD4(+) T cells in draining lymph node (DLN); induced HLA-restricted HSV-gD(53-61), gD(70-78), and gD(278-286)-specific CD8(+) T cells in DLN, conjunctiva, and trigeminal ganglia and reduced HSV-1 replication in tears and corneal eye disease after ocular HSV-1 challenge. In addition, the HSV-1 epitope-specific CD8(+) T cells induced in DLNs, conjunctiva, and the trigeminal ganglia were inversely proportional with corneal disease. The humanized HLA Tg rabbits appeared to be a useful preclinical animal model for investigating the immunogenicity and protective efficacy of human CD8(+) T cell epitope-based prophylactic vaccines against ocular herpes. The relevance of HLA Tg rabbits for future investigation of human CD4-CD8 epitope-based therapeutic vaccines against recurrent HSV-1 is discussed.

Analysis of Ag-presenting cells in the conjunctiva during the development of experimental immune-mediated blepharoconjunctivitis

PURPOSE

The aim of this study was to investigate the phenotypes of antigen (Ag) presenting cells (APCs) in the conjunctiva during the development of experimental immune-mediated blepharoconjunctivitis (EC), which serves as a model for investigation of severe types of human allergic conjunctivitis.

METHODS

Brown Norway rats treated by ovalbumin (OVA) were used in this study. To confirm the restriction of MHC class II by OVA-specific T cells, monoclonal Abs against MHC class II were added to the conventional proliferation assay. To evaluate the MHC class II expression in the conjunctiva during the development of EC, an immunohistochemical analysis, either as the single or double staining, was performed. Conjunctival fibroblast cell lines were established from naive rats and the MHC class II expression was evaluated by flow cytometric analysis. To examine the roles of costimulatory molecules, OVA-specific T cells were stimulated with anti-TcR Ab and anti-CD28 Ab and then subjected for Western blotting to evaluate the ERK phosphorylation. Finally, in vivo expression of B7 molecules was examined immunohistochemically.

RESULTS

OVA-specific T cells recognized OVA in the context of MHC class II. MHC class II was expressed in conjunctival macrophages but not in fibroblasts. EC induction was accompanied by abundant infiltration of macrophages positive for MHC class II. MHC class II was also expressed in conjunctival epithelial cells by EC induction. Stimulation from CD28 was necessary for ERK phosphorylation. B7-2, but not B7-1, was expressed in the conjunctiva.

CONCLUSION

Conjunctival macrophages may represent a major source of APCs for the induction of EC in the conjunctiva.

Dissection of Antigen-Specific Humoral and Cellular Immune Responses for the Development of Experimental Immune-Mediated Blepharoconjunctivitis in C57BL/6 Mice

PURPOSE

Allergic conjunctivitis is characterized by allergen-specific IgE in the serum and infiltration of eosinophils into the conjunctiva. However, it remains unclear whether early-phase reaction (EPR) mediated by Ag-specific IgE links to late-phase reaction (LPR) in the conjunctiva. We aimed to investigate whether LPR is mediated by either cellular or humoral immune responses.

METHODS

Experimental immune-mediated blepharoconjunctivitis (EC) was induced in C57BL/6 mice by either active immunization or passive immunization by transfer of ragweed (RW)-primed lymphocytes and RW-specific IgE, followed by RW challenge onto the conjunctiva. Transferring RW-primed lymphocytes were prepared from RW-primed splenocytes which were stimulated in vitro with RW for 3 days. Fifteen minutes after RW challenge, clinical findings were evaluated and 24 hr after challenge, the conjunctivas and sera were harvested for histologic analysis and measurement of IgE, respectively.

RESULTS

EPR was most prominent when EC was induced by transfer of RW-specific IgE. EPR was hardly detectable if EC was induced by transfer of RW-primed lymphocytes. Mild EPR was noted when EC was induced by active immunization. LPR, evaluated by infiltration of eosinophils into the conjunctiva, was most severe when EC was induced by transfer of RW-primed lymphocytes. Minimal, but definite LPR was induced when EC was induced by transfer of RW-specific IgE. Intermediate severity of LPR was induced when EC was induced by active immunization.

CONCLUSIONS

LPR in the conjunctiva is dominantly mediated by cellular immune responses, whereas EPR in the conjunctiva is putatively mediated by humoral immune responses. Importantly, LPR in the conjunctiva is inducible by Ag-specific IgE alone, although minute.

Predominance of infiltrating IL-4-producing T cells in conjunctiva of patients with allergic conjunctival disease

PURPOSE

Previous reports have suggested that type 2 cytokine responses at the site of inflammation are important in the pathogenesis of allergic disease. In this study, we investigated the frequency of IFN-gamma- or IL-4-producing T cells from conjunctiva or peripheral blood mononuclear cells (PBMC) from patients with allergic conjunctival diseases.

METHODS

We obtained conjunctival samples using Cytobrush and peripheral blood samples from the patients with allergic conjunctival disease. Conjunctival samples and PBMC were stimulated with phorbol myristate acetate and calcium ionophore. Frequencies of cytokine-producing T cells were analyzed by flow cytometry based on the intracellular cytokine staining.

RESULTS

The frequency of IL-4-producing conjunctival T cells in patients with vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC) were significantly higher than that in patients with allergic conjunctivitis (AC). The frequencies of IL-4-producing conjunctival CD4+ T cells of the patients with AC, AKC, or VKC were significantly higher than those of peripheral blood CD4+ T cells of the same disease. Further, increased frequency of P-selectin ligand expressing IL-4-producing T cells was observed in conjunctiva compared to that in PBMC of the patients with allergic conjunctival diseases. The frequencies of IL-4-producing peripheral blood T cells in the patients with ACD were significantly higher than that in normal controls.

CONCLUSION

These results suggest that IL-4-producing T cells that have infiltrated into the conjunctiva play an important role in the immunopathogenesis of allergic conjunctival diseases, and P-selectin ligand is involved in the entry of T cells into allergic inflammatory site.

Ocular anaphylaxis induced in the rat by topical application of compound 48/80. Dose response and time course study

In the present study we sought to develop a model of ocular anaphylaxis based on the topical application of compound 48/80 to the surface of the rat eye. Doses ranging from 50 to 1000 micrograms were found to produce graded edema of the conjunctiva and swelling of the lid. On histologic examination, 50 microns compound 48/80 produced no changes distinguishable from those in PBS-treated controls, 150 microns produced mild alterations, and 250, 500, and 1000 micrograms compound 48/80 produced a marked increase in degranulated mast cells and a mild influx of neutrophils. The time course of the response to 250 micrograms and 1000 micrograms of compound 48/80 was evaluated over a 72-h period. Both doses elicited epithelial damage. A mild reduction in the number of mast cell was seen at 6 h in rats receiving 250 or 1000 micrograms. The reduction persisted to 72 h in rats receiving 1000 micrograms. The number of neutrophils was increased at 1 and 6 h in eyes treated with 250 micrograms and at 1, 6, and 24 h in eyes treated with 1000 micrograms compound 48/80. The clinical and histologic changes induced by application of 250 micrograms compound 48/80 resemble those seen in patients with allergic conjunctivitis suggesting that a model of ocular anaphylaxis based on the topical application compound 48/80 will be clinically relevant and experimentally practical.