Ocular surface inflammation mediated by innate immunity

Differences in gene regulation by TLR3 and IPS-1 signaling in murine corneal epithelial cells

Toll-like receptor 3 (TLR3) and interferon-beta promoter stimulator-1 (IPS-1) are associated with antiviral responses to double-stranded RNA viruses and contribute to innate immunity. We previously reported that conjunctival epithelial cell (CEC) TLR3 and IPS-1 pathways respond to the common ligand polyinosinic:polycytidylic acid (polyI:C) to regulate different gene expression patterns as well as CD11c + cell migration in murine-model corneas. However, the differences in the functions and the roles of TLR3 and IPS-1 remain unclear. In this study, we investigated the differences of TLR3 or IPS-1-induced gene expression in corneal epithelial cells (CECs) in response to polyI:C stimulation using cultured murine primary CECs (mPCECs) derived from TLR3 and IPS-1 knockout mice via comprehensive analysis. The genes associated with viral responses were upregulated in the wild-type mice mPCECs after polyI:C stimulation. Among these genes, Neurl3, Irg1, and LIPG were dominantly regulated by TLR3, while interleukin (IL)-6 and IL-15 were dominantly regulated by IPS-1. CCL5, CXCL10, OAS2, Slfn4, TRIM30α, and Gbp9 were complementarily regulated by both TLR3 and IPS-1. Our findings suggest that CECs may contribute to immune responses and that TLR3 and IPS-1 possibly have different functions in the corneal innate immune response.

Vulvovaginal and ocular involvement and treatment in female patients with Stevens-Johnson syndrome and toxic epidermal necrolysis: A review

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are serious adverse cutaneous drug reactions, characterized by epidermal detachment and mucous membrane involvement. SJS/TEN is more common in female patients, with unique findings in the ocular and vulvar regions. Early recognition and intervention, as well as long-term follow-up, are crucial to prevent devastating scarring and sequelae. This review examines the vulvar and ocular manifestations of SJS/TEN and describes the current treatment recommendations for female patients, requiring close consultation and collaboration among dermatology, ophthalmology, and gynecology.

Understanding Vernal Keratoconjunctivitis: Beyond Allergic Mechanisms

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

Human leucocyte antigen association of patients with Stevens-Johnson syndrome/toxic epidermal necrolysis with severe ocular complications in Han Chinese

BACKGROUND/AIMS

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) induced by cold medicine (CM) may result in severe ocular complications (SOCs). The purpose of this study was to investigate the human leucocyte antigen (HLA) polymorphism pattern in CM-induced patients with SJS/TEN developing SOCs.

METHODS

All participants, including patients with SJS/TEN (n=33) and control patients (n=98), were enrolled through visits to the clinic from 2016 to 2017. SOCs were diagnosed (n=26) via a chart review or eye examination. Patient saliva was collected with commercialised kits and genotyped with PCR assays followed by hybridisation with sequence-specific oligonucleotide (SSO) probes (PCR-SSO) using commercial bead-based typing kits.

RESULTS

In all patients with SJS/TEN with SOCs, the HLA-A*02:07 carrier frequency was significantly higher than that in controls (OR=3.24, 95% CI=1.09 to 9.60, p=0.049), as was the genotype frequency (OR=3.89, 95% CI=1.49 to 10.16, p=0.007). In patients with CM-SJS/TEN with SOCs, the HLA-A*02:07 carrier frequency was higher than that in controls (OR=5.56, 95% CI=1.52 to 20.00, p=0.016), as was the allele frequency (OR=6.67, 95% CI=2.33 to 20.00, p=0.001). In patients with CM-SJS/TEN with SOCs, the HLA-B*46:01 allele frequency was significantly higher than that in controls (OR=3.85, 95% CI=1.52 to 10.00, p=0.008).

CONCLUSIONS

The HLA-A*02:07 and HLA-B*46:01 alleles were significantly associated with SOCs among Han Chinese patients with CM-SJS/TEN. These findings demonstrate the genetic diversity in SJS pathogenesis among different ethnic groups.

Ocular surface disease associated with dupilumab treatment for atopic diseases

Dupilumab is the first US FDA approved biologic for treatment of atopic dermatitis. It is a human monoclonal antibody which blocks the shared receptor component, the interleukin (IL)-4α subunit, of IL-4 and IL-13 signaling pathways. Occurrence of "conjunctivitis", mostly in atopic dermatitis trials, has been the main side effect reported thus far. The etiology of "conjunctivitis" associated with dupilumab treatment is unclear and might be similar to atopic keratoconjunctivitis. There is evidence in the published literature that unlike the Th2-like profile in vernal keratoconjunctivitis, Th1-mediated inflammation is predominant in atopic keratoconjunctivitis. Blocking the Th2 pathway with dupilumab therapy might result in a shift towards Th1, causing the ocular findings associated with dupilumab. In addition, blockage of IL-13 might have implications with regards to mucin production and ocular surface health. This review highlights the clinical manifestations, reviews treatment options and offers explanations for pathogenesis of this ocular surface diseases associated with dupilumab treatment.

Short ragweed pollen promotes M2 macrophage polarization via TSLP/TSLPR/OX40L signaling in allergic inflammation

This study was to explore the role and mechanism of macrophages in pollen-triggered allergic inflammation. A murine model of short ragweed (SRW) pollen-induced experimental allergic conjunctivitis (EAC), and bone marrow (BM)-macrophages cultures were used. Typical allergic manifestations and TSLP-stimulated Th2 hyperresponse were observed in ocular surface of EAC model in wild-type (WT) mice induced by SRW. The M2 phenotype markers, Arg1, Ym1 and FIZZ1, were highly expressed by conjunctiva and draining cervical lymph nodes (CLNs) of WT-EAC mice when compared with controls, as evaluated by RT-qPCR and Immunofluorescent double staining with macrophage marker F4/80. The stimulated expression of TSLPR and OX40L by macrophage was detected in conjunctiva and CLNs by RT-qPCR, double staining, and flow cytometry. M2 macrophages were found to produce TARC and MDC. In contrast, EAC model with TSLPR^-/- mice did not show allergic signs and any increase of Th2 cytokines (IL-4, IL-5 and IL-13) and M2 markers. In vitro cultures confirmed that SRW extract stimulates expression of TSLPR, OX40L, TARC, MDC, and three M2 markers by BM-macrophages from WT mice, but not from TSLPR^-/- mice. These findings demonstrate that SRW pollen primes macrophage polarization toward to M2 phenotype via TSLP/TSLPR/OX40L signaling to amplify allergic inflammation.

Potential Role of Ocular Microbiome, Host Genotype, Tear Cytokines, and Environmental Factors in Corneal Infiltrative Events in Contact Lens Wearers

Purpose

The purpose of this study was to explore differences in genotype, ocular surface microbiome, tear inflammatory markers, and environmental and behavioral exposures in soft contact lens (SCL) wearers with and without a history of corneal infiltrative events (CIEs).

Methods

Nine SCL wearers with a recent CIE and nine age-, sex-, and SCL material- and modality-matched controls were enrolled. The Contact Lens Risk Survey, slit-lamp examination data, basal tears, conjunctival microbial cultures, and peripheral blood samples were collected. Tear inflammatory mediator concentrations, genomic DNA from swabs, and whole exome sequencing of blood samples were quantified.

Results

There were no marked differences in SCL wear behaviors or exposures between case and control subjects. Predominant organisms detected among case and control subjects were Staphylococcus, Propionibacterium, Streptococcus, and Corynebacterium. Marginally higher levels of Neisseria were found in three of nine cases but zero of nine control samples (P = 0.056). A potentially deleterious missense single nucleotide polymorphism (SNP) variant in IL-6 Signal Transducer (IL6ST) was found in seven of eight cases and zero of nine controls (rs2228046; P = 0.03). The concentration of tear IL-6 was significantly higher in cases (4.5 [range, 2.1 to 6.2] pg/mL) versus controls (3.5 [range, 2.5 to 6.6] Pg/mL; = 0.02).

Conclusions

Tear IL-6 concentration was higher, and SNP variants were detected in subjects with a history of CIEs compared with healthy controls. The synthesis, signaling, and ocular surface cytokine concentration of IL-6 may be related to susceptibility to CIE. A larger study population is required to further explore relationships between genetic variations, the ocular surface microbiome, inflammatory mediators, and environmental exposures.

Expression of prostaglandin E2 receptor 3 in the eyelid epidermis of patients with Stevens-Johnson syndrome/toxic epidermal necrolysis

Background/aims

In a previous genome-wide association study of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) patients we reported the association between SJS/TEN and the prostaglandin E receptor 3 (PTGER3) gene, and that its protein PGE2 receptor 3 (EP3) was markedly downregulated in the conjunctival epithelium of SJS/TEN patients. Here we examined EP3 expression of the eyelid epidermis in SJS/TEN patients with severe ocular complications and investigated the function of EP3.

Methods

For the immunohistochemical study, we obtained eyelid samples from five SJS/TEN patients and five patients without SJS/TEN (control subjects) who were undergoing surgery to treat trichiasis, and investigated the expression of EP3 protein in the epidermis of those samples. To investigate the EP3 function in the human epidermal keratinocytes, we performed ELISA and quantitative reverse transcription polymerase chain reaction, since it is reported that PGE2 suppresses cytokine production via EP3 in human conjunctival epithelium.

Results

The results of the immunohistochemical study revealed that EP3 expression in the eyelid epidermis of the SJS/TEN patients was the same as that in the controls. PGE2 and a selective EP3 agonist suppressed cytokine production and expression induced by polyinosine-polycytidylic acid stimulation, such as chemokine ligand 5 and chemokine motif ligand 10.

Conclusion

Our findings revealed that in chronic-phase SJS/TEN, EP3 protein was expressed in the eyelid epidermis and was not downregulated, unlike in conjunctival epithelium, and that PGE2 could suppress cytokine production via EP3 in human epidermal keratinocytes. Thus, EP3 expression in the epidermis might contribute to a silencing of skin inflammation in chronic-phase SJS/TEN.

Ocular surface pathogenesis associated with precocious eyelid opening and necrotic autologous tissue in mouse with disruption of Prickle 1 gene

Ocular surface disease is one major type of eye diseases. Different etiologies trigger distinct pathological responses of the ocular surface. We previously reported that genetically engineered mice with ablation of Prickle 1 manifested precocious eyelid opening with ensuing cornea dysplasia. The current study aimed to characterize the molecular traits and the direct cause of ocular pathology associated with precocious eyelid opening in the Prickle 1 mutant mouse. Prickle 1 mutant mice exhibited a slew of ocular surface pathology including cell proliferation, cell fate transformation and inflammatory infiltration coinciding with the timing of the precocious eyelid opening. Forced eyelid opening in wild type mice did not induce cornea pathology comparable to that of the Prickle 1 mutants. Necrotic tissue debris was found associated with the lesioned cornea. RNAseq analysis of the mutant cornea revealed an expression profile shared by a range of dermatological diseases involving immune responses and cancer. Taken together, the data suggest that the necrotic eyelid debris plays an important role in ocular pathogenesis of the Prickle 1 mutant mouse, which may represent a type of non-infectious keratoconjunctivitis caused by damaged autologous tissues. Additionally, Prickle 1 mutant cornea pathogenesis may offer molecular insights into other types of epithelial pathogenesis.

Inhibitory effect of a novel peptide, H-RN, on keratitis induced by LPS or poly(I:C) in vitro and in vivo via suppressing NF-κB and MAPK activation

Background

Keratitis is a common cause of blindness. Current anti-inflammatory drugs used in keratitis have profound side effects. Small peptides derived from endogenous proteins potentially display both desired efficiency and safety. We identified an 11-amino-acid peptide, H-RN, from hepatocyte growth factor (HGF), an endogenous protein with anti-inflammatory properties. We evaluated the effects of H-RN in keratitis in vitro and in vivo.

Methods

In vitro, corneal fibroblasts were stimulated with LPS or poly(I:C), surrogates for bacteria and viruses. Inflammatory cytokines, intercellular cell adhesion molecule-1 (ICAM-1), translocation of NF-κB p65, activation of IκBα, NF-κB, and MAPKs were detected. In vivo, keratitis in rats was induced by LPS. Clinical, histological observation, and quantification of cytokines in the cornea were conducted. H-RN safety was measured by cell viability, clinical, histological, and microstructural observations.

Results

H-RN inhibited IL-6, monocyte chemotactic protein-1(MCP-1), Interferon- γ(IFN-γ), and ICAM-1 expression triggered by LPS or poly(I:C), alleviated the clinical manifestation and reduced the clinical score in keratitis in vivo. The histological disorder and proinflammatory cytokines of the cornea were also reduced. The translocation of NF-κB and phosphorylation of IκBα, NF-κB, p38, JNK, and ERK were significantly inhibited by H-RN. No sign of toxicity was observed.

Conclusions

H-RN effectively attenuated keratitis in vivo and in vitro induced by LPS or poly(I:C) through blocking NF-κB and MAPK signaling pathways. It may be a promising and safe agent in treating keratitis.

Chronic Ocular Complications of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis: The Role of Systemic Immunomodulatory Therapy

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare, but potentially blinding diseases that affect the skin and mucous membranes. Although the cutaneous manifestations tend to be self-limited and resolve without sequelae, the chronic ocular complications associated with SJS/TEN can persist despite local therapy. Poor understanding of the underlying pathophysiology and lack of a standardized clinical approach have resulted in a paucity of data in regards to suitable treatment options. Inflammatory cellular infiltration and elevated levels of ocular surface cytokines in the conjunctival specimens of affected patients give credence to an underlying immunogenic etiology. Furthermore, the presence of ongoing ocular surface inflammation and progressive conjunctival fibrosis in the absence of exogenous aggravating factors suggest a possible role for systemic immunomodulatory therapy (IMT). We review in detail the proposed immunogenesis underlying chronic ocular SJS/TEN and the possible utility of systemic IMT.

Conjunctival Goblet Cell Function: Effect of Contact Lens Wear and Cytokines

This review focuses on conjunctival goblet cells and their essential function in the maintenance of eye health. The main function of goblet cells is to produce and secrete mucins that lubricate the ocular surface. An excess or a defect in those mucins leads to several alterations that makes goblet cells central players in maintaining the proper mucin balance and ensuring the correct function of ocular surface tissues. A typical pathology that occurs with mucous deficiency is dry eye disease, whereas the classical example of mucous hyperproduction is allergic conjunctivitis. In this review, we analyze how goblet cell number and function can be altered in these diseases and in contact lens (CL) wearers. We found that most published studies focused exclusively on the goblet cell number. However, recent advances have demonstrated that, along with mucin secretion, goblet cells are also able to secrete cytokines and respond to them. We describe the effect of different cytokines on goblet cell proliferation and secretion. We conclude that it is important to further explore the effect of CL wear and cytokines on conjunctival goblet cell function.

Induction of matrix metalloproteinase-1 by tumor necrosis factor-α is mediated by interleukin-6 in cultured fibroblasts of keratoconus

Inflammatory molecules and matrix metalloproteinase (MMPs) have been found over-expressed in the tear film of patients with keratoconus. However, the mechanistic link between inflammatory molecules and MMPs in the pathogenesis of keratoconus remains still elusive. Therefore, we investigated the effect of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) on MMP-1 expression and used IL-6 antibody (IL-6 Ab) to examine the role of IL-6 on TNF-α mediated regulation of MMP-1 in fibroblasts of normal cornea and keratoconus. Real-time polymerase chain reaction, Enzyme-linked immunosorbent assay, and Western blot data demonstrated that MMP-1 and IL-6 were expressed in fibroblasts of normal cornea and keratoconus. Levels of MMP-1 and IL-6 were significantly higher in keratoconus than normal cornea. TNF-α treatment led to a significant increase in IL-6 levels. IL-6 treatment induced MMP-1 synthesis in normal cornea and keratoconus. TNF-α increased MMP-1 expression in a dose- and time-dependent manner and this response was completely inhibited by the IL-6 Ab. In conclusion, these results indicate that fibroblasts of keratoconus shows increased levels of IL-6 and MMP-1 gene and protein expression and IL-6 mediates the TNF-α-induced MMP-1 expression.

A Novel Innate Response of Human Corneal Epithelium to Heat-killed Candida albicans by Producing Peptidoglycan Recognition Proteins

Fungal infections of the cornea can be sight-threatening and have a worse prognosis than other types of microbial corneal infections. Peptidoglycan recognition proteins (PGLYRP), which are expressed on the ocular surface, play an important role in the immune response against bacterial corneal infections by activating toll-like receptors (TLRs) or increasing phagocytosis. However, the role of PGLYRPs in innate immune response to fungal pathogens has not been investigated. In this study, we observed a significant induction of three PGLYRPs 2–4 in primary human corneal epithelial cells (HCECs) exposed to live or heat-killed Candida albicans (HKCA). The C-type lectin receptor dectin-1 plays a critical role in controlling Candida albicans infections by promoting phagocytic activity and cytokine production in macrophages and dendritic cells. Here, we demonstrate that dectin-1 is expressed by normal human corneal tissue and primary HCECs. HKCA exposure increased expression of dectin-1 on HCECs at mRNA and protein levels. Interestingly, dectin-1 neutralizing antibody, IκB-α inhibitor BAY11-7082, and NF-κB activation inhibitor quinazoline blocked NF-κB p65 nuclear translocation, as well as the induction of the PGLYRPs by HKCA in HCECs. Furthermore, rhPGLYRP-2 was found to suppress colony-forming units of Candida albicans in vitro. In conclusion, these findings demonstrate that dectin-1 is expressed by human corneal epithelial cells, and dectin-1/NF-κB signaling pathway plays an important role in regulating Candida albicans/HKCA-induced PGLYRP secretion by HCECs.

Epinephrine enhances the response of macrophages under LPS stimulation

Trauma associated with infection may directly trigger a neuroendocrine reaction in vivo while the hormone epinephrine is known to mediate immune responses to inflammation after injury. However, the role of epinephrine during the earliest stage of trauma still remains unclear. We therefore explored the role of epinephrine on activated macrophages under LPS stimulation in vitro as well as the mechanisms underlying its effect. Dose- and time-dependent effects of epinephrine on macrophage immune function were assessed after LPS activation. We also employed CD14 siRNA interference to investigate whether CD14 played a role in the mechanism underlying the effect of epinephrine on LPS-induced macrophage responses. Our results showed that epinephrine pretreatment (10 ng/mL) significantly promoted immune responses from LPS stimulated macrophages, including phagocytic rate, phagocytic index, TNFα/IL-1β/IL-10 secretion, and CD14 expression (P < 0.05). Moreover, TNFα/IL-1β/IL-10 levels attained their peak value 1 hour after incubation with 10 ng/mL epinephrine (P < 0.05), and CD14 siRNA transfection dramatically decreased phagocytosis and cytokine secretion by LPS-activated macrophages (P < 0.05). We therefore conclude that 10 ng/mL epinephrine enhances immune responses from macrophages under LPS stimulation and that the underlying mechanism may relate to CD14 upregulation on the surface of macrophages.

Erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis: a comparative review

BACKGROUND

Human erythema multiforme (EM) and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) are separate conditions. There is no consensus on classification criteria for the eponymous diseases in animals.

RESULTS

Animal EM is very different from 90% of human EM, which is herpes virus associated (HAEM). Animals lack acrally distributed, typical raised targets. Unlike canine parvovirus 'EM', HAEM is not an active infection. Animal EM is often attributed to drugs, but this is rarely proved. Conversely, human and animal SJS/TEN are almost identical, life-threatening disorders of epidermal necrosis and detachment, typically triggered by drugs (occasionally by infectious agents). Both EM and SJS/TEN are mediated by cytotoxic lymphocyte responses against altered keratinocytes (infectious agents or drugs). Apoptosis results from direct cytotoxicity or through soluble mediators, namely Fas ligand, granzymes, perforin and granulysin. Diagnosis in humans is clinicopathological, with emphasis on clinical lesions; histopathology confirms the pathological process as interface (cytotoxic) dermatitis. Human EM is self-limiting; only recurrent and rare persistent cases require antiviral/immunosuppressive therapies. Drug-induced EM responds to drug withdrawal. Idiopathic canine EM (>40%) is usually chronic, refractory to treatment and may represent heterogeneous conditions. Early identification and removal of the causative drug and high-quality supportive care are critical in SJS/TEN. Mortality rate is nevertheless high.

CONCLUSIONS AND CLINICAL IMPORTANCE

(1) Histopathological lesions do not reliably differentiate EM, SJS and TEN. (2) A multicentre study to develop a consensus set of clinical criteria for EM and SJS/TEN in animals is overdue. (3) No adjunctive therapies, including intravenous immunoglobulin and ciclosporin, have met evidence-based standards.

Human corneal epithelial cells produce antimicrobial peptides LL-37 and β-defensins in response to heat-killed Candida albicans

AIMS

To explore the innate response of human corneal epithelial cells (HCECs) exposed to fungus by producing antimicrobial peptides LL-37 and β-defensins.

METHODS

Primary HCECs were treated with heat-killed Candida albicans (HKCA) at different doses (10(3)-10(6) cells/ml) for 2-48 h. The cells were subjected to total RNA extraction, reverse transcription and quantitative real-time PCR for mRNA expression. Cells treated for 48 h were used for immunofluorescent staining and ELISA.

RESULTS

Human LL-37 and β-defensins (hBDs) 1-4 were detected in normal HCECs. The mRNA expression of LL-37, hBD2, and hBD3 was dose-dependently induced by HKCA with their peak levels at 4 h. HKCA (10(6) cells/ml) stimulated the mRNA of LL-37, hBD2, and hBD3 4.33 ± 1.81, 3.75 ± 1.31, and 4.91 ± 1.09 fold, respectively, in HCECs. The stimulated production of LL-37, hBD2, and hBD3 by HKCA was confirmed at protein levels by immunofluorescent staining and ELISA. The protein production of LL-37, hBD2, and hBD3 significantly increased to 109.1 ± 18.2 pg/ml, 4.33 ± 1.67 ng/ml, and 296.9 ± 81.8 pg/ml, respectively, in culture medium of HCECs exposed to HKCA (10(6) cells/ml) compared to untreated HCECs.

CONCLUSIONS

HCECs produce antimicrobial peptides, LL-37, hBD2 and hBD3, in response to stimulation of HKCA, which suggests a novel innate immune mechanism of the ocular surface in defense against fungal invasion.

Elevation of conjunctival epithelial CD45INTCD11b⁺CD16⁺CD14⁻ neutrophils in ocular Stevens-Johnson syndrome and toxic epidermal necrolysis

PURPOSE

Ocular complications related to Stevens-Johnson Syndrome (SJS)-Toxic Epidermal Necrolysis (TEN) may persist and progress after resolution of systemic disease. This is thought to be related in part to persistent ocular innate-immune signaling. In this study, our aim was to characterize infiltrative conjunctival cellular profiles during acute (<12 months) and chronic (>12 months) disease.

METHODS

Consecutive patients presenting with SJS-TEN over a 12-month period were followed for 1 year. Detailed clinical examination and conjunctival impression cell recovery was analyzed by flow cytometry for the presence of intraepithelial leukocytes and compared with healthy controls (n = 21).

RESULTS

Ten patients were recruited of whom six had acute disease and five were classified as TEN (SCORTEN = 1, n = 4). Conjunctival inflammation was graded as absent/mild in a total of nine patients; but despite this, evidence of fornix shrinkage was observed in nine subjects. This inversely correlated with disease duration (P < 0.05). A reduction in percentage of CD8αβ(+) T cells compared with controls (80% vs. 57%; P < 0.01) was associated with a corresponding increase in the number/percentage of CD45(INT)CD11b(+)CD16(+)CD14(-) neutrophils (186 vs. 3.4, P < 0.01, 31% vs. 0.8%, P < 0.001). Neutrophils inversely correlated with disease duration (r = -0.71, P = 0.03), yet there was no absolute change in the CD8αβ(+) or neutrophil populations during the study period (P = 1.0).

CONCLUSIONS

These data highlight that a neutrophilic infiltrate is present in mildly inflamed or clinically quiescent conjunctival mucosa in patients with ocular SJS-TEN, where neutrophil numbers inversely correlate with disease duration. Neutrophil persistence endorses the hypothesis of an unresolved innate-inflammatory process that might account for disease progression.

Prostaglandin E2 suppresses poly I: C-stimulated cytokine production via EP2 and EP3 in immortalized human corneal epithelial cells

PURPOSE

We previously reported that prostaglandin (PG) E2 acts as a ligand for prostaglandin E receptor 3 (EP3) in conjunctival epithelial cells, that it downregulates the progression of experimental murine allergic conjunctivitis, and that in human conjunctival epithelial cells it modulates the expression of polyI:C-induced proinflammatory genes via prostaglandin E receptor 2 (EP2) and EP3, suggesting that PGE2 might have important roles in ocular surface inflammation such as allergic conjunctivitis. Here, we investigated whether PGE2 also downregulates polyI:C-induced cytokine production in human corneal epithelial cells.

METHODS

We used enzyme-linked immunosorbent assay and quantitative reverse transcription-polymerase chain reaction to examine the effects of PGE2 on polyI:C-induced cytokine expression by immortalized human corneal-limbal epithelial cells (HCLE). Using reverse transcription-polymerase chain reaction, we examined the messenger RNA (mRNA) expression of the PGE2 receptor, EP1-4.

RESULTS

PGE2 significantly attenuated the expression of CC chemokine ligand (CCL)5 (P < 0.0005), CCL20 (P < 0.0005), C-X-C chemokine (CXCL)10 (P < 0.0005), CXCL11 (P < 0.05), and interleukin (IL)-6 (P < 0.005) in human corneal-limbal epithelial cells. Human corneal epithelial cells manifested the mRNA expression of EP2, EP3, and EP4, but not EP1. The EP2 agonist significantly suppressed the polyI:C-induced expression of CCL5 (P < 0.005), CXCL10 (P < 0.0005), and CXCL11 (P < 0.05) but not of CCL20 and IL-6. The EP3 agonist significantly suppressed the expression of CCL5 (P < 0.05), CCL20 (P < 0.005), CXCL10 (P < 0.0005), CXCL11 (P < 0.0005), and IL-6 (P < 0.005). The EP4 agonist failed to suppress cytokine production induced by polyI:C stimulation.

CONCLUSIONS

Our results show that in human corneal epithelial cells, PGE2 attenuated the mRNA expression and production of CCL5, CXCL10, and CXCL11 via both EP2 and EP3, and that the mRNA expression and production of CCL20 and IL-6 was attenuated only by EP3.

In vitro effect of a corrosive hostile ocular surface on candidate biomaterials for keratoprosthesis skirt

Aim

Keratoprosthesis (KPro) devices are prone to long-term corrosion and microbiological assault. The authors aimed to compare the inflammatory response and material dissolution properties of two candidate KPro skirt materials, hydroxyapatite (HA) and titania (TiO₂) in a simulated in vitro cornea inflammation environment.

Methods

Lipopolysaccharide-stimulated cytokine secretions were evaluated with human corneal fibroblasts on both HA and TiO₂. Material specimens were subjected to electrochemical and long-term incubation test with artificial tear fluid (ATF) of various acidities. Topography and surface roughness of material discs were analysed by scanning electron microscopy and atomic force microscopy.

Results

There were less cytokines secreted from human corneal fibroblasts seeded on TiO₂ substrates as compared with HA. TiO₂ was more resistant to the corrosion effect caused by acidic ATF in contrast to HA. Moreover, the elemental composition of TiO₂ was more stable than HA after long-term incubation with ATF.

Conclusions

TiO₂ is more resistant to inflammatory degradation and has a higher corrosion resistance as compared with HA, and in this regard may be a suitable material to replace HA as an osteo-odonto-keratoprosthesis skirt. This would reduce resorption rates for KPro surgery.

Nuclear Factor-κB: central regulator in ocular surface inflammation and diseases

The nuclear factor-κB (NF-κB) is a key transcription factor pathway that is responsible for many key biological processes, such as inflammation, apoptosis, stress response, corneal wound healing, angiogenesis, and lymphangiogenesis. Numerous recent studies have investigated NF-κB in the context of ocular surface disorders, including chemical injury, ultraviolet radiation-induced injury, microbial infections, allergic eye diseases, dry eye, pterygium, and corneal graft rejection. The purpose this article is to summarize key findings with regard to the pathways regulating NF-κB and processes governed by the NF-κB pathway. In the innate defense system, NF-κB is involved in signaling from the toll-like receptors 2, 3, 4, 5 and 7, which are expressed in conjunctival, limbal, and corneal epithelial cells. These determine the ocular responses to infections, such as those caused by Pseudomonas aeruginosa, Staphylococcus aureus, adenovirus, and herpes simplex-1 virus. Natural angiogenic inhibitors enhance NF-κB, and this may occur through the mitogen-activated protein kinases and peroxisome proliferator-activated receptor γ. In alkali injury, inhibition of NF-κB can reduce corneal angiogenesis, suggesting a possible therapeutic strategy. The evaluation of NF-κB inhibitors in diseases is also discussed, including emodin, besifloxacin, BOL-303242-X (mapracorat), thymosin-β4, epigallocatechin gallate, Perilla frutescens leaf extract and IKKβ-targeting short interfering RNA.

Expression of interleukin-4 receptor α in human corneal epithelial cells

PURPOSE

We previously reported that human conjunctival epithelial cells expressed functioning interleukin-4 receptor α (IL-4Rα). In this study, we investigated whether human corneal epithelial cells also express functioning IL-4Rα.

METHODS

The presence of IL-4Rα mRNA and protein in human corneal epithelium was examined by reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistology, respectively. The cell surface expression of IL-4Rα and the transcripts upregulated upon IL-4Rα ligand (IL-4 or IL-13) stimulation were examined by flow cytometry and quantitative RT-PCR, respectively, using immortalized human corneal-limbal epithelial (HCLE) cells.

RESULTS

The mRNA and protein of IL-4Rα were detected in human corneal epithelium. Flow cytometry analysis showed the cell surface expression of IL-4Rα protein. Quantitative RT-PCR assay of HCLE cells showed the upregulation of the transcripts tumor necrosis factor alpha-induced protein 6 (TNFAIP6), RAS guanyl-releasing protein 1 (RASGRP1), carbonic anhydrase II (CA2), cytokine-inducible SH2-containing protein (CISH), hyaluronan synthase 3 (HAS3), calpain 14 (CAPN14), endothelin receptor type A (EDNRA), cathepsin C (CTSC), and lecithin retinol acyltransferase (LRAT) as well as human conjunctival epithelial cells.

CONCLUSION

Human corneal epithelial cells expressed functioning IL-4Rα, and stimulation of its ligands, IL-4 and IL-13, could induce the expression of various genes, e.g., antiinflammatory molecule genes such as TNFAIP6 and CISH and cellular differentiation and proliferation-related molecule genes such as RASGRP1, HAS3, EDNRA, and LRAT.

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.