Corticosteroid and doxycycline suppress MMP-9 and inflammatory cytokine expression, MAPK activation in the corneal epithelium in experimental dry eye

EMMPRIN modulates epithelial barrier function through a MMP-mediated occludin cleavage: implications in dry eye disease

Dry eye is a common disease that develops as a result of alteration of tear fluid, leading to osmotic stress and a perturbed epithelial barrier. Matrix metalloproteinase-9 (MMP-9) may be important in dry eye disease, as its genetic knockout conferred resistance to the epithelial disruption. We show that extracellular matrix metalloproteinase inducer (EMMPRIN; also termed CD147), an inducer of MMP expression, participates in the pathogenesis of dry eye through MMP-mediated cleavage of occludin, an important component of tight junctions. EMMPRIN expression was increased on the ocular surface of dry eye patients and correlated with those of MMP-9. High osmolarity in cell culture, mimicking dry eye conditions, increased both EMMPRIN and MMP-9 and resulted in the disruption of epithelial junctions through the cleavage of occludin. Exogenously added recombinant EMMPRIN had similar effects that were abrogated in the presence of the MMP inhibitor marimastat. Membrane occludin immunostaining was markedly increased in the apical corneal epithelium of both EMMPRIN and MMP-9 knock-out mice. Furthermore, an inverse correlation between EMMPRIN and occludin membrane staining was consistently observed both in vitro and in vivo as a function of corneal epithelial cells differentiation. These data suggest a possible role of EMMPRIN in regulating the amount of occludin at the cell surface in homeostasis beyond pathological situations such as dry eye disease, and EMMPRIN may be essential for the formation and maintenance of organized epithelial structure.

Homeostatic control of conjunctival mucosal goblet cells by NKT-derived IL-13

Although the effects of the interleukin 13 (IL-13) on goblet cell (GC) hyperplasia have been studied in the gut and respiratory tracts, its effect on regulating conjunctival GC has not been explored. The purpose of this study was to determine the major IL-13-producing cell type and the role of IL-13 in GC homeostasis in normal murine conjunctiva. Using isolating techniques, we identified natural killer (NK)/natural killer T (NKT) cells as the main producers of IL-13. We also observed that IL-13 knockout (KO) and signal transducer and activator of transcription 6 knockout (STAT6KO) mice had a lower number of periodic acid Schiff (PAS)+GCs. We observed that desiccating stress (DS) decreases NK population, GCs, and IL-13, whereas it increases interferon-γ (IFN-γ) mRNA in conjunctiva. Cyclosporine A treatment during DS maintained the number of NK/NKT cells in the conjunctiva, increased IL-13 mRNA in NK+ cells, and decreased IFN-γ and IL-17A mRNA transcripts in NK+ and NK- populations. C57BL/6 mice chronically depleted of NK/NKT cells, as well as NKT cell-deficient RAG1KO and CD1dKO mice, had fewer filled GCs than their wild-type counterparts. NK depletion in CD1dKO mice had no further effect on the number of PAS+ cells. Taken together, these findings indicate that NKT cells are major sources of IL-13 in the conjunctival mucosa that regulates GC homeostasis.

TLR-mediated induction of pro-allergic cytokine IL-33 in ocular mucosal epithelium

Interleukin (IL) 33 has been recently identified as a ligand to the ST2 receptor that mediates Th2-dominant allergic inflammation. The purpose of this study was to explore the role of toll-like receptor (TLR)-mediated innate immunity in IL-33 induction by mucosal epithelium. Human corneal tissues and cultured primary human corneal epithelial cells (HCECs) were treated with a variety of viral or bacterial components without or with different inhibitors to evaluate the IL-33 regulation and signaling pathways. The level of mRNA expression was determined by reverse transcription and real time PCR, and protein was measured by ELISA, immunostaining and Western blotting. IL-33 mRNA and protein were largely induced by various microbial components, mainly by polyI:C and flagellin, the ligands to TLR3 and TLR5, respectively in human corneal epithelium ex vivo and in vitro cultures. Pro-IL-33 protein was normally restricted inside cells, and could be secreted outside when activated by ATP. The PolyI:C induced IL-33 production was blocked by TLR3 antibody or TRIF Inhibitory peptide, while flagellin stimulated IL-33 was blocked by TLR5 antibody or MyD88 Inhibitory peptide. Interestingly, IκB-α inhibitor (BAY11-7082) or NF-κB inhibitor (quinazoline) blocked NF-κB p65 protein nuclear translocation, and suppressed IL-33 production induced by PolyI:C and flagellin. These findings demonstrate that IL-33, an epithelium-derived pro-allergic cytokine, is induced by microbial ligands through TLR-mediated innate signaling pathways, suggesting a possible role of mucosal epithelium in Th2-dominant allergic inflammation.

Tear osmolarity in the diagnosis and management of dry eye disease

PURPOSE

To evaluate the use of tear osmolarity in the diagnosis of dry eye disease.

DESIGN

A prospective, observational case series to determine the clinical usefulness of tear osmolarity and commonly used objective tests to diagnose dry eye disease.

METHODS

A multicenter, 10-site study consisting of 314 consecutive subjects between 18 and 82 years of age. Bilateral tear osmolarity, tear film break-up time (TBUT), corneal staining, conjunctival staining, Schirmer test, and meibomian gland grading were performed. Diagnostic performance was measured against a composite index of objective measurements that classified subjects as having normal, mild or moderate, or severe dry eye. The main outcome measures were sensitivity, specificity, area under the receiver operating characteristic curve, and intereye variability.

RESULTS

Of the 6 tests, tear osmolarity was found to have superior diagnostic performance. The most sensitive threshold between normal and mild or moderate subjects was found to be 308 mOsms/L, whereas the most specific was found at 315 mOsms/L. At a cutoff of 312 mOsms/L, tear hyperosmolarity exhibited 73% sensitivity and 92% specificity. By contrast, the other common tests exhibited either poor sensitivity (corneal staining, 54%; conjunctival staining, 60%; meibomian gland grading, 61%) or poor specificity (tear film break-up time, 45%; Schirmer test, 51%). Tear osmolarity also had the highest area under the receiver operating characteristic curve (0.89). Intereye differences in osmolarity were found to correlate with increasing disease severity (r(2) = 0.32).

CONCLUSIONS

Tear osmolarity is the best single metric both to diagnose and classify dry eye disease. Intereye variability is a characteristic of dry eye not seen in normal subjects.

An immunoprotective privilege of corneal epithelial stem cells against Th17 inflammatory stress by producing glial cell-derived neurotrophic factor

Adult stem cells are well known for their self-renewal and regenerative capacity. The mechanisms protecting these cells from inflammatory damage have not been well elucidated. This study investigated the immunoprotective properties of corneal epithelial stem cells from inflammation by producing glial cell-derived neurotrophic factor (GDNF). Primary human limbal epithelial cells (HLECs) cultured from limbal explants were treated with interleukin (IL)-17A, tumor necrosis factor (TNF)-α, or hyperosmotic media, with or without GDNF or nuclear factor kappa B (NF-κB) inhibitor (NF-κB-I) for 4-48 hours. Inflammatory mediators and Th17-inducing cytokines were determined by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and immunobead assays. NF-κB activation was detected by p65 phosphorylation, immunostaining and Western blotting. GDNF and its receptor, GDNF family receptor α-1, were exclusively immunolocalized in the basal layer of limbal epithelium, whereas IL-17 receptor was negative in these cells. Exogenous IL-17A stimulated the expression and production of inflammatory cytokines (TNF-α, IL-6, and IL-1β) and chemokine IL-8 by HLECs. Th17-inducing cytokines, transforming growth factor (TGF)-β1, IL-6, IL-23, and IL-1β, were significantly increased at mRNA and protein levels by HLECs exposed to TNF-α or hyperosmotic media. IL-17 activated NF-κB by p65 phosphorylation at serine 536 and nuclear translocation. GDNF or NF-κB-I blocked IL-17-induced NF-κB p65 activation and production of inflammatory mediators. Furthermore, GDNF suppressed the production of Th17-inducing cytokines through inhibiting NF-κB activation. These findings demonstrate that limbal progenitor cell-produced neurotrophic factor GDNF suppresses IL-17-mediated inflammation via NF-κB signaling pathway. This may represent a unique immunoprotective property of limbal stem cells against inflammatory challenges on the ocular surface.

Effective long-term control of refractory hidradenitis suppurativa with adalimumab after failure of conventional therapy

BACKGROUND

Hidradenitis suppurativa is a chronic suppurative condition featuring inflammatory nodules, fistulas and scars. It occurs predominantly in the axillae and groin. The disease is poorly responsive to any treatment and is connected with significant morbidity. Systemic therapy, including oral antibiotics, retinoids and antiandrogens, usually has only limited effect. Surgical treatment of affected areas is necessary in advanced stages.

OBJECTIVES

Several reports support the beneficial effect of tumor necrosis factor-α (TNF-α) antagonists for the treatment of severe hidradenitis suppurativa. By contrast with data on infliximab and etanercept, data describing the potential positive influence of adalimumab on disease outcome are limited and refer to only small cohorts of patients.

METHODS

Eight patients with severe, recalcitrant hidradenitis were treated for 1 year with adalimumab in a standard regimen and were subsequently followed for 1 year.

RESULTS

All patients improved within 4-6 weeks and laboratory parameters of C-reactive protein (CRP) and leukocyte count reduced significantly during treatment. Three patients demonstrated long-lasting improvement and five showed recurrences several months after discontinuation of the therapy. The average recurrence-free interval was 9.5 months.

CONCLUSIONS

Adalimumab is suitable for the long-term treatment of hidradenitis suppurativa and presents a further conservative treatment approach.

Aberrant DNA methylation of matrix remodeling and cell adhesion related genes in pterygium

Background

Pterygium is a common ocular surface disease characterized by abnormal epithelial and fibrovascular proliferation, invasion, and matrix remodeling. This lesion, which migrates from the periphery to the center of the cornea, impairs vision and causes considerable irritation. The mechanism of pterygium formation remains ambiguous, and current treatment is solely surgical excision, with a significant risk of recurrence after surgery. Here, we investigate the role of methylation in DNA sequences that regulate matrix remodeling and cell adhesion in pterygium formation.

Methodology/Principal Findings

Pterygium and uninvolved conjunctiva samples were obtained from the same eye of patients undergoing surgery. The EpiTYPER Sequenom technology, based on differential base cleavage and bisulfite sequencing was used to evaluate the extent of methylation of 29 matrix and adhesion related genes. In pterygium, three CpG sites at −268, −32 and −29 bp upstream of transglutaminase 2 (TGM-2) transcription initiation were significantly hypermethylated (p<0.05), whereas hypomethylation was detected at CpGs +484 and +602 bp downstream of matrix metalloproteinase 2 (MMP-2) transcription start site, and −809, −762, −631 and −629 bp upstream of the CD24 transcription start site. RT-qPCR, western blot and immunofluorescent staining showed that transcript and protein expression were reduced for TGM-2 and increased for MMP-2 and CD24. Inhibition of methylation in cultured conjunctival epithelial cells increased these transcripts.

Conclusions/Significance

We found regions of aberrant DNA methylation which were consistent with alteration of TGM-2, MMP-2, and CD24 transcript and protein expression, and that inhibition of methylation in cultured cells can increase the expression of these genes. Since these genes were related to cell adhesion and matrix remodeling, dysregulation may lead to fibroblastic and neovascular changes and pterygium formation. These results have implications for the prognostication of pterygium in clinical practice, for example, detection of epigenetic changes may have a role in predicting post surgical recurrence of aggressive lesions.

Dry eye disease as an inflammatory disorder

PURPOSE

Dry eye disease (DED) is a prevalent inflammatory disorder of the lacrimal functional unit of multifactorial origin leading to chronic ocular surface disease, impaired quality of vision, and a wide range of complications, eventually causing a reduction in quality of life. It still is a frustrating disease because of the present scarcity of therapies that can reverse, or at least stop, its progression.

METHODS

A comprehensive literature survey of English-written scientific publications on the role of inflammation in DED.

RESULTS

New investigations have demonstrated that a chronic inflammatory response plays a key role in the pathogenesis of human DED. Additionally, correlations between inflammatory molecules and clinical data suggest that inflammation can be responsible for some of the clinical symptoms and signs.

CONCLUSIONS

Research efforts to clarify its pathophysiology are leading to a better understanding of DED, demonstrating that inflammation, in addition to many other factors, plays a relevant role.

The β-catenin/Tcf4/survivin signaling maintains a less differentiated phenotype and high proliferative capacity of human corneal epithelial progenitor cells

It is clear that the microenvironment or niche plays an important role in determining the fate of stem cells: being stem cells or differentiated. However, the intrinsic pathways controlling the fate of adult stem cells in different niches are largely unknown. This study was to explore the role of β-catenin/Tcf4/survivin signaling in determining the fate of human corneal epithelial stem cells in different media. We observed that the low calcium serum-free media, especially CnT-20, promoted proliferative capacity, colony forming efficiency and stem cell-like phenotype of human corneal epithelial cells (HCECs) when compared with the cells cultured in a high calcium serum-containing medium SHEM. Three key factors in Wnt signaling, β-catenin, Tcf4 and survivin, were found to be expressed higher by HCECs grown in CnT-20 than those cultured in SHEM, as evaluated by real-time PCR, Western blotting and immunostaining. Transfection of siRNA-Tcf4 at 10-50nM knocked down Tcf4, and also significantly suppressed its down stream molecule survivin at both mRNA and protein levels in HCECs. Furthermore, Tcf4 silencing significantly suppressed the proliferative capacity of HCECs, measured by WST-1 assay, compared with the control groups, untreated or transfected with non-coding sequence siRNA-fluorescein. These findings demonstrate that low calcium serum free media promote ex vivo expansion of corneal epithelial progenitor cells that retain a less differentiated phenotype and high proliferative capacity via β-catenin/Tcf4/survivin signaling, a novel intrinsic pathway. This study may have high impact and clinic implication on the expansion of corneal epithelial stem cells in regenerative medicine, especially for ocular surface reconstruction.

The effect of doxycycline temperature-sensitive hydrogel on inhibiting the corneal neovascularization induced by BFGF in rats

BACKGROUND

To study the effect of doxycycline temperature-sensitive hydrogel (DTSH) on inhibiting the corneal neovascularization (NV) induced by the basic fibroblast growth factor (bFGF).

METHODS

Corneal NV was induced by slow-release polymer pellets containing bFGF, using a rat corneal pocket model. After being implanted with bFGF pellets, the female Sprague-Dawley rats were randomly divided into seven groups (12 rats/group). The grouped rats were given topically normal saline solution and neutralized DTSH at a concentration of 0%, 0.01%, 0.05%, 0.1%, 0.5%, and 1% respectively, and treated for 6 consecutive days. After 6 days of treatment, the cornea was perfused with India ink. The length and area of the corneal vessel were measured and analyzed by Image Pro-Plus 5.1.

RESULTS

Compared to the control group given saline solution, the study groups given DTSH at a concentration of 0.05%, 0.1%, 0.5%, and 1% showed significant reduction in the vessel length (respectively, 58%, 60%, 52%, and 37%) and the vessel area (respectively, 61%, 62%, 49%, and 39%) (p < 0.001). However, no such significant reduction was observed in the study group given 0.01% DTSH (p = 0.133 and 0.166 for vessel length and area respectively). Study groups given 0.05% and 0.1% DTSH showed better effects than groups given 0.01% and 1% DTSH with regard to reducing the vessel length and the vessel area (p < 0.05).

CONCLUSION

The study results showed that topical DTSH effectively inhibited corneal NV at the ideal concentration of 0.05% and 0.1%. Therefore, topical DTSH could be considered as an alternative treatment for the clinical management of corneal NV.

Advancements in anti-inflammatory therapy for dry eye syndrome

PURPOSE

The goal of this literature review is to discuss recent discoveries in the pathophysiology of dry eye and the subsequent evolution of diagnostic and management techniques. The mechanisms of various anti-inflammatory treatments are reviewed, and the efficacy of common pharmacologic agents is assessed. Anti-inflammatory therapy is evaluated in terms of its primary indications, target population, and utility within a clinical setting.

METHODS

The Medline PubMed database and the World Wide Web were searched for current information regarding dry eye prevalence, pathogenesis, diagnosis, and management. After an analysis of the literature, major concepts were integrated to generate an updated portrayal of the status of dry eye syndrome.

RESULTS

Inflammation appears to play a key role in perpetuating and sustaining dry eye. Discoveries of inflammatory markers found within the corneal and conjunctival epithelium of dry eye patients have triggered recent advancements in therapy. Pharmacologic anti-inflammatory therapy for dry eye includes 2 major categories: corticosteroids and immunomodulatory agents. Fatty acid and androgen supplementation and oral antibiotics have also shown promise in dry eye therapy because of their anti-inflammatory effects.

CONCLUSIONS

Anti-inflammatory pharmacologic agents have shown great success in patients with moderate to severe dry eye when compared with alternative treatment modalities. A deeper understanding of the link between inflammation and dry eye validates the utilization of anti-inflammatory therapy in everyday optometric practice.

Suppressive effects of azithromycin on zymosan-induced production of proinflammatory mediators by human corneal epithelial cells

PURPOSE

In addition to its antibiotic effects, azithromycin has been noted to have anti-inflammatory activity, particularly in the context of microbial infections. This study was conducted to explore the suppressive effects of azithromycin on the production of proinflammatory mediators by human corneal epithelial cells (HCECs) stimulated by a fungal component, zymosan.

METHODS

Primary HCECs were cultured from donor corneal limbal explants and grown to subconfluence. The cells were treated with toll-like receptor (TLR) 2 agonist zymosan (1-50 μg/mL) for 4 to 48 hours, with or without preincubation with azithromycin (1-50 μg/mL), TLR2 antibody, or NF-κB activation inhibitor quinazoline (NF-κB-I). The cells were subjected to total RNA extraction, reverse transcription (RT), and real-time PCR using gene expression assays. Cells treated for 48 hours were used for immunofluorescence staining and Western blot analysis, and their medium supernatants were collected for protein quantitation by immunobead assays.

RESULTS

The mRNA expression and protein production of proinflammatory cytokines (TNF-α and IL-1β), chemokines (IL-8 and RANTES), and matrix metalloproteinases (MMP-1, -3, and -9) by HCECs were stimulated by zymosan in a concentration-dependent manner, with peak levels noted at 4 hours. These stimulated levels of proinflammatory mediators by zymosan were significantly inhibited by TLR2 antibody, NF-κB-I, or azithromycin, which blocked zymosan-induced NF-κB activation as determined by p65 protein nuclear translocation.

CONCLUSIONS

These findings demonstrated that the fungal component zymosan induces proinflammatory responses through TLR2 and NF-κB signaling pathways, whereas azithromycin suppresses its stimulation by blocking NF-κB activation in HCECs, suggesting the potential efficacy of this antibiotic for treating ocular surface inflammatory disorders.

The therapeutic effect of DA-6034 on ocular inflammation via suppression of MMP-9 and inflammatory cytokines and activation of the MAPK signaling pathway in an experimental dry eye model

PURPOSE

To investigate the effect of DA-6034, 7-carboxymethyloxy-3',4',5-trimethoxy flavone, in experimentally-induced inflammatory dry eye in rabbit. In addition, to elucidate the mechanism of DA-6034, we evaluated the mitogen-activated protein kinase (MAPK) signaling pathway and transcriptional factor-kappa B (NF-kB) in corneal epithelial cells.

METHODS

Rabbit lacrimal glands were injected with the T-cell mitogen concanavalin A (Con A). DA-6034 was then administered topically four times a day for six days starting 24 hr after Con A injection. Tear volume, tear function, MMP-9 and inflammatory cytokine levels in the lacrimal glands, and histological evaluation were subsequently assessed. In in vitro study, phosphorylated MAPKs (c-Jun NH2-terminal kinase (JNK) and p38 MAPK) and NF-kB were detected by enzyme-linked immunosorbent assay (ELISA) using human corneal epithelial cells.

RESULTS

A single injection of Con A into the lacrimal glands induced a pronounced inflammatory response, caused elevated levels of MMP-9 and cytokines IL-8 and TGF-beta(1), and induced a decrease in tear volume and shortening of tear breakup time (TBUT). In this inflammation model of dry eye, DA-6034 clearly showed therapeutic efficacy by restoring tear function and inhibiting inflammatory responses after topical ocular application. Furthermore, DA-6034 attenuated the phosphorylation of JNK and p38 MAPK and inhibited NF-kB activation in a concentration-dependent manner in corneal epithelial cells.

CONCLUSIONS

These results suggest that DA-6034 has the therapeutic effect in rabbit lacrimal gland inflammation model of dry eye and might be a potential treatment option for acute dry eye syndrome.

Molecular signatures and biological pathway profiles of human corneal epithelial progenitor cells

Identification and isolation of adult stem cells are still challenging for stem cell biologists. For example, no consensus exists yet regarding definitive markers for corneal epithelial stem cells, which have been identified to reside in the limbus for two decades. This study characterized the molecular signatures and biological pathways of limbal epithelial progenitors, the rapid adherent cells (RAC) isolated by adhesion on collagen IV, using human genome microarrays, real-time PCR and immunofluorescent staining. The microarrays produced highly reproducible data not only for all gene transcripts, but also for significantly changed genes, although the total 12 samples of 3 cell populations in 2 arrays were isolated from 4 separate experiments at different time period. The hierarchical clustering heatmap visually revealed that RAC progenitor population displayed distinguishably characteristic gene expression profile. With verification of 27 important genes by quantitative real-time PCR, the microarray data not only confirm the expression patterns of 15 known genes as stem cell associated markers representing limbal stem cell phenotype, but also identified many significantly regulated genes expressed by limbal progenitor cells. Transcription factor TCF4 and cell surface protein SPRRs were identified as potentially positive or negative markers, respectively, for corneal epithelial progenitor cells. Using GenMAPP and MAPPFinder, we have identified three patterns of biological pathway profiles, overexpressed, underexpressed and balanced, by RAC progenitors based on gene ontology categories. These genes and related pathways are interesting targets for further identification and isolation of limbal stem cells as well as other tissue-specific adult stem cells.

Desiccating stress promotion of Th17 differentiation by ocular surface tissues through a dendritic cell-mediated pathway

PURPOSE

To explore the phenomenon that corneal and conjunctival tissues subjected to desiccating stress (DS) promote Th17 differentiation by stimulating the production of Th17-inducing cytokines through a dendritic cell (DC)-mediated pathway.

METHODS

Experimental dry eye was created by subjecting C57BL/6 mice to desiccating environmental stress. Corneal and conjunctival explants from dry eye or control mice were cocultured with DCs for 24 hours before CD4(+) T cells were added for an additional 4 to 7 days. Expression of Th17-associated genes in the cornea, conjunctiva, DCs, and CD4(+) T cells was evaluated by real-time PCR. Cytokine concentrations in coculture supernatants were measured by immunobead assay. IL-17-producing T cells were identified by ELISPOT bioassay.

RESULTS

Higher levels of IL-17A, TGF-beta1, TGF-beta2, IL-6, IL-23, and IL-1beta mRNA transcripts and TGF-beta1, IL-6, and IL-1beta protein were observed in corneal epithelium and conjunctiva from dry eye mice. DCs cocultured with epithelial explants from dry eye mice for 2 days produced higher levels of TGF-beta1, IL-6, IL-23, and IL-1beta mRNA transcripts and of TGF-beta1, IL-6, and IL-1beta protein. CD4(+) T cells cocultured with DCs and epithelial explants from dry eye mice expressed increased levels of IL-17A, IL-17F, IL-22, CCL-20, and retinoic acid receptor-related orphan receptor-gammat mRNA transcripts and increased IL-17A protein and number of IL-17-producing T cells (Th17 cells).

CONCLUSIONS

These findings demonstrate that DS creates an environment on the ocular surface that stimulates the production of Th17-inducing cytokines by corneal and conjunctival epithelia that promote Th17 differentiation through a dendritic cell-mediated pathway.

TSLP and downstream molecules in experimental mouse allergic conjunctivitis

PURPOSE

To explore the potential role of thymic stromal lymphopoietin (TSLP) and its downstream molecules in the development of ocular allergic inflammation using a short ragweed (SRW)-induced mouse model of allergic conjunctivitis (AC).

METHODS

BALB/c mice were topically challenged with SRW pollen after they were sensitized with SRW in the footpad. After the last SRW challenge, the corneal epithelium, conjunctiva, and cervical lymph nodes were harvested for total RNA extraction and gene expression by RT and real-time PCR, and whole eye globes were collected to make cryosections for immunohistochemical staining.

RESULTS

Repeated topical challenges with SRW allergen generated typical signs of AC in mice. Compared with the untreated controls, TSLP mRNA expression and immunoreactivity were significantly increased in the corneal and conjunctival epithelia of SRW-induced AC mice. CD11c(+) and OX40L(+) immunoreactive cells largely infiltrated the conjunctiva with increased mRNA levels of CD11c, TSLPR, and OX40L detected in the corneal epithelium, conjunctiva, and cervical lymph nodes. CD4(+) Th2 cell infiltration was evidenced by increased levels of mRNA and immunoreactivity of CD4, IL-4, IL-5, and IL-13 in the ocular surface, mainly in the conjunctiva, accompanied by increased expression of OX40, STAT6, and GATA3, in AC mice. The maturation of immature DCs was observed with the use of TSLP containing conditioned media from corneal epithelial cultures exposed to polyI:C, which stimulates TSLP production.

CONCLUSIONS

This study provides new findings regarding the role of local mucosal epithelial cells in the initiation of ocular allergic inflammation by producing a novel proallergic cytokine, TSLP, which activates dendritic cells to prime Th2 differentiation and allergic inflammation through the TSLP-TSLPR and OX40L-OX40 signaling pathway.

Essential role for c-Jun N-terminal kinase 2 in corneal epithelial response to desiccating stress

OBJECTIVE

To investigate the protective effects of c-Jun N-terminal kinase (JNK)-1 and -2 gene knockout (KO) on the corneal epithelial response to desiccating stress.

METHODS

The C57BL/6, JNK1KO, and JNK2KO mice were subjected to desiccating stress (DS) for 5 days. The effects of DS on the corneal epithelium were evaluated by measuring corneal smoothness and permeability. Expression of matrix metalloproteinases (MMP)-1, MMP-9, and cornified envelope protein precursors (small proline-rich protein [SPRR]-1a, SPRR-2a, and involucrin) in the corneal epithelia was evaluated by immunostaining and real-time polymerase chain reaction. Collagenase and gelatinase activity in corneal sections as measured with in situ fluorescent assays.

RESULTS

The JNK2KO mice had smoother corneal surfaces and less corneal barrier disruption in response to DS than JNK1KO mice and C57BL/6 wild-type control mice. The DS increased levels of MMP-1, MMP-9, SPRR-1a, SPRR-2a, involucrin immunoreactivity, and mRNA transcripts in the corneal epithelium of JNK1KO and C57BL/6 mice, but not in JNK2KO mice. Knockout of JNK2 prevented DS-induced increase in gelatinase and collagenase activity in the cornea.

CONCLUSION

The JNK2 protein appears to have an essential role in desiccation-induced corneal epithelial disease by stimulating production of MMP-1, MMP-9, and cornified envelope precursors. Clinical Relevance The JNK2 protein could be a novel therapeutic target in dry eye disease.

Induction of Th17 differentiation by corneal epithelial-derived cytokines

This study was to explore a potential role of epithelium-derived cytokines in Th17 differentiation. Th17 induction was evaluated by murine CD4(+) T cells treated with different combinations of five inducing cytokines, or conditioned media of human corneal epithelial cells (HCECs) exposed to a variety of stimuli. Th17 differentiation was determined by measuring Th17 associated molecules, IL-17A, IL-17F, IL-22, CCL-20, and STAT3 at mRNA and protein levels, and numbers of IL-17-producing T cells by real-time PCR, and cytokine immunobead and ELISPOT assays, respectively. IL-23 was the strongest inducer for expanding Th17 cells in the presence of TGF-beta1 + IL-6; and IL-1beta was the strongest Th17 amplifier in the presence of TGF-beta1 + IL-6 + IL-23. These inducing cytokines were found to be significantly stimulated in HCECs challenged by hyperosmotic media (450 mOsM), microbial components (polyI:C, flagellin, R837, and other TLR ligands) and TNF-alpha. Interestingly, when incubated with conditioned media of HCECs irritated by polyI:C or TNF-alpha, CD4(+) T cells displayed increased mRNA levels of IL-17A, IL-17F, IL-22, CCL-20, and STAT3, increased IL-17 protein in the supernatant, and increased numbers of IL-17-producing T cells (Th17 cells). These findings demonstrate for the first time that Th17 differentiation can be promoted by cytokines produced by corneal epithelium that are exposed to hyperosmotic, microbial, and inflammatory stimuli.

In vivo characterization of doxycycline effects on tear metalloproteinases in patients with chronic blepharitis

PURPOSE

Matrix metalloproteinases (MMPs) have a role in the pathogenesis of rosacea-associated chronic blepharitis. Doxycycline is largely used as a treatment for recalcitrant chronic blepharitis. It has been shown in vitro that doxycycline inhibits MMPs activation. The aim of this study was to investigate in vivo the effect of doxycycline in modulating MMPs in patients with chronic idiopathic blepharitis.

METHODS

Eight patients (6 male, 2 female; mean age 45.7+/-17.5 years) were included in the study. Doxycycline (100 mg) was administered orally, twice a day, for 2 weeks and once a day for an additional 2 weeks. Clinical signs and symptoms were evaluated and scored (0-3) at baseline and after 4 weeks. Total sign (TSS) and total symptom (TSyS) scores were calculated. Tear samples and conjunctival impression cytologies were collected at baseline and after 4 weeks of treatment to evaluate MMP-9 and TIMP-1 expression and activity.

RESULTS

An improvement in TSS (4.5+/-1.1 vs 2.7+/-1.5) and TSyS (6.6+/-1.3 vs. 3.1+/-1.9) was observed after 4 weeks, with significant amelioration of hyperemia, marginal blepharitis, and superficial punctuate keratopathy. Zymography revealed a decrease of MMP-9 activity after 4 weeks. MMP-9 mRNA and protein levels did not change, while an upregulation of TIMP-1 expression was observed.

CONCLUSIONS

This study suggests that 4-week treatment with doxycycline significantly improved symptoms and signs in patients with chronic blepharitis in association with a decrease in MMP-9 activity. Upregulation of TIMP-1 is proposed as a possible mechanism of MMP-9 inactivation.

Cleavage of functional IL-2 receptor alpha chain (CD25) from murine corneal and conjunctival epithelia by MMP-9

BACKGROUND

IL-2 has classically been considered a cytokine that regulates T cell proliferation and differentiation, signaling through its heterotrimeric receptor (IL-2R) consisting of alpha (CD25), beta (CD122), gamma chains (CD132). Expression of IL-2R has also been detected in mucosal epithelial cells. Soluble IL-2Ralpha (CD25) has been reported as an inflammatory marker. We evaluated the expression of CD25 and CD122 in the ocular surface epithelium and investigated the mechanism of proteolytic cleavage of CD25 from these cells.

METHODS

Desiccating stress (DS) was used as an inducer of matrix metalloproteinase 9 (MMP-9). DS was created by subjecting C57BL/6 and MMP-9 knockout (BKO) mice and their wild-type littermates (WT) mice to a low humidity and drafty environment for 5 days (DS5). A separate group of C57BL/6 mice was subjected to DS5 and treatment with topical 0.025% doxycycline, a MMP inhibitor, administered QID. The expression of CD25 and CD122 was evaluated in cryosections by dual-label laser scanning confocal microscopy. Western blot was used to measure relative levels of CD25 in epithelial lysates. Gelatinase activity was evaluated by in situ zymography. Soluble CD25 in tear fluid was measured by an immunobead assay.

RESULTS

CD25 and CD122 were abundantly expressed in cornea (all layers) and conjunctiva epithelia (apical and subapical layers) in nonstressed control mice. After desiccating stress, we found that immunoreactivity to CD25, but not CD122, decreased by the ocular surface epithelia and concentration of soluble CD25 in tears increased as MMP-9 staining increased. CD25 was preserved in C57BL/6 mice topically treated with an MMP-9 inhibitor and in MMP-9 knock-out mice. MMP-9 treatment of human cultured corneal epithelial cells decreased levels of CD25 protein in a concentration dependent fashion.

CONCLUSION

Our results indicate that functional IL-2R is produced by the ocular surface epithelia and that CD25 is proteolytic cleaved to its soluble form by MMP-9, which increases in desiccating stress. These findings provide new insight into IL-2 signaling in mucosal epithelia.

Doxycycline loaded poly(ethylene glycol) hydrogels for healing vesicant-induced ocular wounds

Half mustard (CEES) and nitrogen mustard (NM) are commonly used surrogates and vesicant analogs of the chemical warfare agent sulfur mustard. In the current study, in situ forming poly(ethylene glycol) (PEG)-based doxycycline hydrogels are developed and evaluated for their wound healing efficacy in CEES and NM-exposed rabbit corneas in organ culture. The hydrogels, characterized by UV-Vis spectrophotometry, rheometry, and swelling kinetics, showed that the hydrogels are optically transparent, have good mechanical strength and a relatively low degree of swelling (<7%). In vitro doxycycline release from the hydrogel disks (0.25% w/v) was found to be biphasic with release half times of approximately 12 and 72h, respectively, with 80-100% released over a 7-day period. Permeation of doxycycline through vesicant wounded corneas was found to be 2.5 to 3.4 fold higher than non-wounded corneas. Histology and immunofluorescence studies showed a significant reduction of matrix metalloproteinase-9 (MMP-9) and improved healing of vesicant-exposed corneas by doxycycline hydrogels compared to a similar dose of doxycycline delivered in phosphate buffered saline (PBS, pH 7.4). In conclusion, the current studies demonstrate that the doxycycline-PEG hydrogels accelerate corneal wound healing after vesicant injury offering a therapeutic option for ocular mustard injuries.

Toll-like receptors mediate induction of peptidoglycan recognition proteins in human corneal epithelial cells

Human peptidoglycan recognition proteins (PGLYRPs) are a novel family of pattern recognition receptors, and also act as anti-bacterial proteins. This study was to explore the toll-like receptor (TLR)-mediated regulation of PGLYRPs in human corneal epithelial cells (HCECs). Fresh human donor corneoscleral tissues were used to prepare cryosections. Primary HCECs, established from limbal explants, were treated with microbial ligands to TLRs 1-9 for 4-48 h, with or without pretreatment of TLR antibodies, NFkB inhibitor, or siRNA transfection. The mRNA of PGLYRPs was evaluated by RT and real-time PCR, and their proteins and NFkB activation were determined by immunostaining and Western blot. The nuclear IRF3 activity was quantified using an ELISA-based TransAM kit. PGLYRP-2, -3 and -4 were found to be expressed by human corneal epithelium while PGLYRP-1 was not detected. In primary HCEC cultures, PGLYRP-3 and -4 were constitutively expressed while PGLYRP-2 was largely inducible. PGLYRP-2 was induced by bacterial components, Pam3CSK4, PGN, flagellin and FSL-1, ligands for TLR2/1, 2, 5 and 2/6, respectively. Interestingly, PGLYRP-2 was strongest stimulated by polyI:C representing viral dsRNA. TLR3 antibody or NFkB inhibitor blocked IRF3 and NFkB p65 activation as well as polyI:C-stimulated PGLYRP-2. RNA interference indicates that the polyI:C-induced PGLYRP-2 was dramatically blocked in the cells transfected with siRNA-TRIF but neither siRNA-MyD88 nor the negative control siRNA-F. These findings suggest that human corneal epithelium may response to viral or bacterial infection by producing PGLYRPs through TLRs, and the induction of PGLYRP-2 by dsRNA was through TLR3-TRIF-IRF3-NFkB signaling pathways.

Acidic mammalian chitinase in dry eye conditions

PURPOSE

An acidic mammalian chitinase (AMCase) seems to be implicated in allergic asthma and allergic ocular pathologies. The aim of this work was to investigate the role of AMCase during Sjögren's Syndrome (SS) and Meibomian Gland Dysfunction (MGD) dry eye diseases.

METHODS

Six patients with MGD dry eye (20-58 years, median 40) and six patients with dry eye associated to SS (32-60 years, median 47) were enrolled in this study. AMCase activity was measured in tears and AMCase mRNA expression was evaluated by real-time polymerase chain reaction from RNA extracted from epithelial cells of the conjunctiva. Six healthy adult subjects of the same age (34-44 years, median 39) were also studied as the control group.

RESULTS

AMCase activity was significantly increased in patients affected by MGD dry eye (18.54 +/- 1.5 nmol/ml/h) and SS dry eye (8.94 +/- 1.0 nmol/ml/h) respectively, compared to healthy controls (1.6 +/- 0.2 nmol/ml/h). AMCase activity was higher in the tears of subjects with MGD dry eye (P < 0.001). AMCase mRNA was detected in conjunctival epithelial cells and the expression was significantly higher in MGD dry eye than SS dry eye. A significant correlation between AMCase activity in the tears and mRNA in conjunctival epithelial cells was found.

CONCLUSION

AMCase may be an important marker in the pathogenesis of dry eye, suggesting the potential role of AMCase as a therapeutic target in these frequent pathologies.

Effects of DA-6034 on aqueous tear fluid secretion and conjunctival goblet cell proliferation

PURPOSE

This study was conducted to evaluate the effect of DA-6034, a potent secretagogue, on aqueous tear fluid secretion and its quality in normal rabbit. We also evaluated, in animal models of experimentally induced dry eye disease, its effectiveness over time to stimulate aqueous tear production by ocular ferning test and goblet cell proliferation.

METHODS

Aqueous tear production, total protein levels, and glycoprotein levels in normal rabbits were evaluated after topical application of DA-6034 (0.3, 1, and 3%). Moreover, time course aqueous tear volume measurement and ocular ferning test in tear fluid were performed in dry eyes of rabbits that had been given 1% atropine sulfate, topically. Altogether, tear fluid production and conjunctival goblet cell numbers were measured in dry eyes of mice that had been given topical scopolamine.

RESULTS

Topical application of DA-6034 (0.3, 1, and 3%) significantly increased (P < 0.05) aqueous tear production in a concentration-dependent manner in normal rabbits. There was no change in total protein levels while glycoprotein levels were significantly increased (P < 0.05) at 3% DA-6034. The increase in aqueous tear fluid was significant (P < 0.05) and lasted for 2 h post-instillation in dry eyes of rabbits that had been given 1% atropine sulfate; 10-day repeated instillation of the drug in this model resulted in large and homogeneous fern-like tear patterns. In a mouse model, DA-6034 given as a 3% eyedrop solution significantly increased (P < 0.05) tear fluid production and conjunctival goblet cell number.

CONCLUSIONS

These results suggest that DA-6034 accelerates not only tear secretion but also mucin production and may be a potential therapeutic agent for the treatment of dry eye disease.

[The "wet" dry eye]

Dry eye is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability, with potential damage to the ocular surface. The two main causes are reduced production of aqueous tears and increased evaporation of tears. The evaporative form of dry eye results in ocular surface irritation with a secondary increase in tear production; this presents to the examiner and patient as a wet eye or epiphora. Knowledge and understanding of the basic pathologies and differential diagnoses of dry eye disease are essential to differentiate this very common form of dry eye from disorders of the lacrimal drainage system and to initiate adequate management.

Doxycycline-mediated inhibition of choroidal neovascularization

PURPOSE

Doxycycline, a broad-spectrum antibiotic, has certain antiangiogenic properties and can inhibit matrix metalloproteinases (MMPs/gelatinases). The authors investigated the effects of doxycycline on choroidal neovascularization (CNV) and regulation of MMP-2 and -9 and pigment epithelium-derived factor (PEDF).

METHODS

Doxycycline was orally administered to rats at 500, 50, 5, and 0.5 mg/kg/d; nontreated animals were used as controls. Experimental CNV was induced with laser 7 days after doxycycline treatment started. At 7 days after induction, animals were euthanatized, and eyes were collected. RPE/choroid flatmounts were labeled with isolectin IB4 to determine CNV lesion volumes using confocal microscopy and high-performance 3D imaging software. MMP-2, MMP-9, and PEDF protein levels were determined by ELISA. MMP catalytic activity was determined in solution using fluorogenic gelatin and peptide substrates, by gelatin zymography in SDS-PAGE, and by in situ fluorogenic substrate zymography in RPE/choroid sections.

RESULTS

CNV complex lesion volumes decreased with doxycycline in a dose-response relationship. A dosage of 500 mg/kg/d caused a 70% inhibition of CNV complex volume compared with control animals. Doxycycline elevated PEDF levels in plasma and did not affect the active and pro-enzymes MMP-2 and MMP-9 levels. However, the in vitro enzymatic activities of purified MMP-2 and MMP-9 declined significantly with doxycycline. MMP-2, MMP-9, and gelatinolytic activities in situ increased early in CNV lesion development. Doxycycline treatments and exogenous additions inhibited gelatinolytic activities in CNV lesions.

CONCLUSIONS

Doxycycline effectively hampered the progression of experimental CNV. The results suggest that orally administrated doxycycline can reach the choroid to attenuate proteolytic enzymes that remodel Bruch's membrane and promote the antiangiogenic PEDF to inhibit neovascularization.

IL-17 disrupts corneal barrier following desiccating stress

T helper (Th)-17 is a recently identified subtype of Th response that has been implicated in host defense and autoimmunity. We investigated whether there is evidence for a Th-17 response in human and experimental murine dry eye (DE). Gene expression in the human DE conjunctiva showed increased levels of the Th-17 inducers, interleukin (IL)-23, IL-17A, and interferon-gamma (IFN-gamma). In the murine model, we found that desiccating stress increased matrix metalloproteinase-9, Th-17-associated genes (IL-6, IL-23, transforming growth factor-beta1 and -2, IL-23R, IL-17R, IL-17A, retinoid-related orphan receptor-gammat, and CC chemokine attractant ligand-20) and IFN-gamma in cornea and conjunctiva. Furthermore, we found a significantly increased concentration of IL-17 in tears and number of IL-17-producing cells on the ocular surface. Antibody neutralization of IL-17 ameliorated experimental DE-induced corneal epithelial barrier dysfunction and decreased the expression of matrix metalloproteinases 3 and 9. Taken together, these findings suggest that IL-17 has a role in corneal epithelial barrier disruption in DE.

Human corneal epithelium-derived thymic stromal lymphopoietin links the innate and adaptive immune responses via TLRs and Th2 cytokines

PURPOSE

To explore the crucial role of the human corneal epithelium-derived proallergic cytokine thymic stromal lymphopoietin (TSLP) in initiation and regulation of immune responses.

METHODS

Primary corneal epithelial cells, established from donor limbal explants, were treated with 11 microbial ligands and proinflammatory and Th2 cytokines, alone or in combination. TSLP mRNA and protein were determined by real-time PCR and ELISA, respectively. NF-kappaB activation was detected by immunostaining and Western blot.

RESULTS

TSLP was found to be expressed by human corneal epithelium and its cultures. TSLP in corneal epithelial cells were largely induced in a concentration-dependent fashion by polyI:C, flagellin, and FSL-1, the ligands for toll-like receptor (TLR)-3, -5, and -6, respectively. Compared with the control, TSLP mRNA was increased by 60-, 12- and 8-fold and TSLP protein increased by 67-, 19- and 7-fold by these three ligands, respectively. The proinflammatory (TNF-alpha and IL-1beta) and Th2 (IL-4 and IL-13) cytokines moderately induced TSLP expression and production. IL-4 and -13 strongly synergized with PolyI:C, flagellin, and TNF-alpha to promote TSLP production in ex vivo tissues and in vitro cultures of corneal epithelium. PolyI:C, flagellin, or TNF-alpha also induced NF-kappaB p65 protein nuclear translocation. The NF-kappaB inhibitor quinazoline blocked p65 nuclear translocation and further suppressed TSLP expression and production induced by these stimuli.

CONCLUSIONS

These findings provide the first evidence of TSLP induction in the human eye and suggest the novel phenomenon that human corneal epithelium-derived TSLP may serve as a link between the innate and adaptive immune responses. TSLP may become a novel therapeutic target for allergic and inflammatory ocular surface diseases.

Topical apolipoprotein A-1 may have a beneficial effect on the corneal epithelium in a mouse model of dry eye: a pilot study

PURPOSE

Dry-eye syndrome affects millions of individuals and it is essential to develop effective therapeutic agents for the treatment of this complex condition. The goal of this study was to evaluate the effect of apolipoprotein A (ApoA)-1 and its synergistic action with d-pantethine (DP) on corneal epithelial disorders in dry-eye mouse model.

METHODS

Aqueous tear production of C57BL/6J Jms Slc male mice aged 10 to 12 weeks were inhibited by subcutaneous scopolamine injection and mice were placed in a continuous airflow blower to create desiccating environmental stress. During desiccation, 1 eye of each mouse was treated with ApoA-1 (0.01%, 0.04%, or 0.1%) or ApoA-1 (0.04%) + DP (0.05%, 0.1%, or 0.2%) and the other control eye was instilled with phosphate-buffered saline 4 times daily for 5 days. Phenol red thread test, corneal fluorescein staining (score, 0-4), and measurement of corneal epithelial thickness measurements were performed.

RESULTS

Significant reductions of staining scores and higher corneal epithelial thickness values were observed in both ApoA-1- and ApoA-1 + DP-treated groups compared with untreated dry-eye mouse and phosphate-buffered saline-treated group.

CONCLUSIONS

These results suggest that ApoA-1 and DP may be potential therapeutic agents for ocular surface epithelial disorders in patients with dry eye.

Desiccating stress decreases apical corneal epithelial cell size--modulation by the metalloproteinase inhibitor doxycycline

PURPOSE

We investigated the effects of desiccating stress on murine corneal apical epithelial cell area and desquamation by using 4 defined parameters and evaluated the effects of the metalloproteinase inhibitor doxycycline on this process.

METHODS

C57BL/6 mice were subjected to experimental dry eye (EDE) for 5 days without or with topical therapy with doxycycline 0.025% or 0.0025% or vehicle 4 times a day. C57BL/6 mice that were not exposed to desiccating stress served as controls. Whole mount corneas from each group were immunostained for occludin and visualized by laser scanning confocal microscopy. The images were analyzed in a masked fashion, and mean individual cell area, apical cell density, average cell number loss, and average percent loss were recorded.

RESULTS

EDE caused a significant decrease in apical corneal cell area (1073 +/- 135.9 microm2), an increase in apical cell density (895.8 +/- 115.4 cells per mm2) and a greater percent of epithelial loss (21.29% +/- 13.40%) than controls (1341 +/- 95.28 microm2, 714.4 +/- 55.60 cells per mm2, 2.897% +/- 3.452%, P < 0.001 for all, respectively). Treatment with 0.025% doxycycline preserved cell area (1337 +/- 144.6 microm2) and the apical cell density (721.0 +/- 91.62 cells per mm2) and decreased percentage loss (5.117% +/- 6.757%) compared with the vehicle control group (1154 +/- 88.10 microm2, 830.2 +/- 49.76 cells per mm2, 22.14 +/- 9.616%, P < 0.001 for all, respectively).

CONCLUSIONS

Desiccating stress decreases apical corneal epithelial cell area, increases apical cell density, and promotes epithelial cell loss. Treatment with the metalloproteinase inhibitor doxycycline during desiccating stress preserves cell area and apical cell density and prevents EDE-induced corneal epithelial cell loss. These findings suggest that metalloproteinases mediate apical corneal epithelial loss during desiccating stress.

Advances in understanding and managing dry eye disease

PURPOSE

To present evidence from the literature and scientific meetings to support fundamental changes in concepts regarding the prevalence, pathogenesis, definition, diagnosis, management of dry eye disease (DED) and the prospects for the development of new therapies.

DESIGN

Analysis and clinical perspective of the literature and recent presentations.

METHODS

Review and interpretation of literature.

RESULTS

The tear film and ocular surface form an integrated physiologic unit linking the surface epithelia and secretory glands via a neural network. This sensory-driven network regulates secretory activity in quantity and composition, supporting the homeostasis of the system. The tear film forms a metastable covering between blinks, subserving clear vision, and maintains the health and turnover of the ocular surface cells. Disturbance of intrinsic factors such as increasing age; hormonal balance; systemic or local autoimmune disease, or both; systemic drugs or extrinsic factors including topical medications; environmental stress; contact lens wear; or refractive surgery result in a final common pathway of events at the tear film and ocular surface, resulting in DED. Diagnosis of DED and the design of clinical trials for new drugs have been hampered by a lack of correlation between signs and symptoms and flawed endpoints; successful new drug applications likely will require new approaches, such as the use of objective biomarkers for disease severity.

CONCLUSIONS

Recent advances in our knowledge of the causation of DED open opportunities for improving diagnosis and disease management and for developing new, more effective therapies to manage this widely prevalent and debilitating disease state.

Effects of osmoprotectants on hyperosmolar stress in cultured human corneal epithelial cells

PURPOSE

Increased tear osmolarity in dry eye disease has been found to stimulate production of inflammatory cytokines and matrix metalloproteinases by ocular surface epithelial cells. Prokaryotic and mammalian organ system cells maintain normal function under hypertonic conditions by the synthesis or accumulation of osmoprotectant compounds. This study assessed the effect of osmoprotectant compounds on the activation state of mitogen-activated protein (MAP) kinases in human corneal epithelial cells incubated in hyperosmolar conditions.

METHODS

Human corneal epithelial cells were incubated in media of isotonic, physiological osmolarity (300 mOsm) and in hyperosmolar media (400 mOsm), in the presence and absence of osmoprotectants, including several amino acids (L-carnitine and betaine), glycerol, and the polyol erythritol. The phosphorylation (activation) states of c-Jun N-terminal kinases (JNK) and p38 MAP kinases were monitored by Western blot and bead-based immunoassays.

RESULTS

Hyperosmolar conditions achieved by addition of sodium chloride or sucrose increased ratios of phosphorylated JNK and p38 to total JNK and p38. Compared with controls, 10 mM L-carnitine or 40 mM erythritol significantly lowered levels of activated MAP kinases in response to hyperosmolar stress. They also lowered ratios of phosphorylated to total kinases to barely detectable levels in cells cultured in isotonic media.

CONCLUSIONS

The osmoprotectants L-carnitine and erythritol, alone or in combination, were found to protect against stress activation of corneal epithelial cells cultured in hyperosmolar media.

Desiccating environmental stress exacerbates autoimmune lacrimal keratoconjunctivitis in non-obese diabetic mice

The non-obese diabetic (NOD) mouse is prone to develop autoimmune disease, including Sjögren's syndrome. The purpose of this study was to determine if desiccating environmental stress exacerbates the development of Sjögren's syndrome-like lacrimal keratoconjunctivitis in the NOD.B10.H2(b) mouse. Four-week-old male mice were used as young controls. Sixteen-week-old male mice were untreated or subjected to desiccating stress with a fan alone or with a fan plus subcutaneous injections of the anticholinergic agent scopolamine for 5 or 10 days to inhibit tear production. Mice spontaneously developed Sjögren's syndrome-like lacrimal keratoconjunctivitis as they aged. Desiccating stress increased CD4+ and CCR5+ cells and decreased CD8+ cells in the conjunctival epithelium and lacrimal gland. Intraepithelial gammadelta T cells significantly decreased after 5 days and returned to baseline levels after 10 days in both groups exposed to desiccating stress. These immunopathological changes were accompanied by a decrease in conjunctival goblet cell density. Greater matrix metalloproteinase-9 production, gelatinase activity and loss of epithelial cell membrane CD25 immunoreactivity was noted in the ocular surface epithelia of stressed mice. These findings indicate that desiccating environmental stress aggravates Sjögren's syndrome-like lacrimal keratoconjunctivitis in the NOD mouse which has defective immunoregulation.

p38 MAPK signaling in oral-related diseases

Multiple dental diseases are characterized by chronic inflammation, due to the production of cytokines, chemokines, and prostanoids by immune and non-immune cells. Membrane-bound receptors provide a link between the extracellular environment and the initiation of intracellular signaling events that activate common signaling components, including p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and nuclear factor (NF)-kappaB. Although ERK pathways regulate cell survival and are responsive to extracellular mitogens, p38 MAPK, JNK, and NF-kappaB are involved in environmental stress responses, including inflammatory stimuli. Over the past decade, significant advances have been made relative to our understanding of the fundamental intracellular signaling mechanisms that govern inflammatory cytokine expression. The p38 MAPK pathway has been shown to play a pivotal role in inflammatory cytokine and chemokine gene regulation at both the transcriptional and the post-transcriptional levels. In this review, we present evidence for the significance of p38 MAPK signaling in diverse dental diseases, including chronic pain, desquamative disorders, and periodontal diseases. Additional information is presented on the molecular mechanisms whereby p38 signaling controls post-transcriptional gene expression in inflammatory states.

Future directions in therapeutic interventions for conjunctival inflammatory disorders

PURPOSE OF REVIEW

To review recent advances in pathogenesis and treatment of conjunctival inflammatory disorders.

RECENT FINDINGS

The conjunctiva becomes inflamed in a number of conditions, including allergy, atopy, dry eye, mucus membrane pemphigoid, Stevens-Johnson syndrome and surgical manipulation. Basic and clinical studies have identified a number of inflammatory mediators as potential therapeutic targets in these conditions. Additionally, new therapeutic agents and enhanced delivery systems have been evaluated.

SUMMARY

Increased understanding of the key mediators of conjunctival inflammation coupled with improved drug delivery methods are leading to more effective therapy for conjunctival inflammatory disorders.

The Definition and Classification of Dry Eye Disease: Report of the Definition and Classification Subcommittee of the International Dry Eye Workshop (2007)

The aim of the DEWS Definition and Classification Subcommittee was to provide a contemporary definition of dry eye disease, supported within a comprehensive classification framework. A new definition of dry eye was developed to reflect current understanding of the disease, and the committee recommended a three-part classification system. The first part is etiopathogenic and illustrates the multiple causes of dry eye. The second is mechanistic and shows how each cause of dry eye may act through a common pathway. It is stressed that any form of dry eye can interact with and exacerbate other forms of dry eye, as part of a vicious circle. Finally, a scheme is presented, based on the severity of the dry eye disease, which is expected to provide a rational basis for therapy. These guidelines are not intended to override the clinical assessment and judgment of an expert clinician in individual cases, but they should prove helpful in the conduct of clinical practice and research.

Management and Therapy of Dry Eye Disease: Report of the Management and Therapy Subcommittee of the International Dry Eye WorkShop (2007)

The members of the Management and Therapy Subcommittee assessed current dry eye therapies. Each member wrote a succinct evidence-based review on an assigned aspect of the topic, and the final report was written after review by and with consensus of all subcommittee members and the entire Dry Eye WorkShop membership. In addition to its own review of the literature, the Subcommittee reviewed the Dry Eye Preferred Practice Patterns of the American Academy of Ophthalmology and the International Task Force (ITF) Delphi Panel on Dry Eye. The Subcommittee favored the approach taken by the ITF, whose recommended treatments were based on level of disease severity. the recommendations of the Subcommittee are based on a modification of the ITF severity grading scheme, and suggested treatments were chosen from a menu of therapies for which evidence of therapeutic effect had been presented.