Anti-inflammatory effect of IL-6 receptor blockade in corneal alkali burn

Nanoceria-Mediated Cyclosporin A Delivery for Dry Eye Disease Management through Modulating Immune-Epithelial Crosstalk

Dry eye disease (DED) affects a substantial worldwide population with increasing frequency. Current single-targeting DED management is severely hindered by the existence of an oxidative stress-inflammation vicious cycle and complicated intercellular crosstalk within the ocular microenvironment. Here, a nanozyme-based eye drop, namely nanoceria loading cyclosporin A (Cs@P/CeO2), is developed, which possesses long-term antioxidative and anti-inflammatory capacities due to its regenerative antioxidative activity and sustained release of cyclosporin A (CsA). In vitro studies showed that the dual-functional Cs@P/CeO2 not only inhibits cellular reactive oxygen species production, sequentially maintaining mitochondrial integrity, but also downregulates inflammatory processes and repolarizes macrophages. Moreover, using flow cytometric and single-cell sequencing data, the in vivo therapeutic effect of Cs@P/CeO2 was systemically demonstrated, which rebalances the immune-epithelial communication in the corneal microenvironment with less inflammatory macrophage polarization, restrained oxidative stress, and enhanced epithelium regeneration. Collectively, our data proved that the antioxidative and anti-inflammatory Cs@P/CeO2 may provide therapeutic insights into DED management.

Comparative Analysis of the Osmoprotective Effects of Daily Disposable Contact Lens Packaging Solutions on Human Corneal Epithelial Cells

Purpose

Contact lens (CL) wear challenges the balance of the ocular surface environment by increasing water evaporation and tear osmolarity. Maintaining ocular surface homeostasis during CL wear remains a goal of lens manufacturers and an important consideration for eye care professionals. The purpose of this study was to measure the metabolic activity and inflammatory responses of a transformed human corneal epithelial cell (THCEpiC) line under hyperosmotic conditions in the presence of CL packaging solutions.

Methods

CL packaging solutions sampled from seven daily disposable silicone hydrogel CL blister packages were prepared at 25% and made hyperosmolar (400 mOsm/kg) with NaCl. THCEpiCs were incubated with each solution for 24 hr, after which cell culture supernatants were collected. THCEpiC metabolic activity was determined by an alamarBlue assay. Concentrations in cell culture supernatants of inflammatory cytokine (interleukin [IL]-6) and chemokine (IL-8), as well as monocyte chemoattractant protein-1 (MCP-1), were quantitated by specific enzyme-linked immunosorbent assays.

Results

THCEpiC metabolic activity under hyperosmolar conditions decreased in the presence of somofilcon A and senofilcon A solutions (p=0.04 and 0.004, respectively), but no other solution (all p≥0.09). Concentrations of IL-6 increased in the presence of delefilcon A, somofilcon A, narafilcon A, and senofilcon A solutions (all p≤0.001), but no other solution (all p≥0.08), while those of IL-8 increased in the presence of all solutions (all p≤0.03) but kalifilcon A (p>0.99), and those of MCP-1 increased in the presence of delefilcon A, verofilcon A, somofilcon A, and stenfilcon A solutions (all p<0.0001), but no other solution (all p>0.99).

Conclusion

CL packaging solutions differ in their capacity to inhibit epithelial inflammation. THCEpiC inflammatory response was less in the presence of a CL packaging solution containing osmoprotectants than in solutions lacking osmoprotectants under moderately hyperosmolar conditions in vitro. Clinical studies are warranted to further substantiate the benefit of osmoprotectants.

The role of the JAK/STAT3 signaling pathway in acquired corneal diseases

Acquired corneal diseases such as dry eye disease (DED), keratitis and corneal alkali burns are significant contributors to vision impairment worldwide, and more effective and innovative therapies are urgently needed. The Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling pathway plays an indispensable role in cell metabolism, inflammation and the immune response. Studies have shown that regulators of this pathway are extensively expressed in the cornea, inducing significant activation of JAK/STAT3 signaling in specific acquired corneal diseases. The activation of JAK/STAT3 signaling contributes to various pathophysiological processes in the cornea, including inflammation, neovascularization, fibrosis, and wound healing. In the context of DED, the hypertonic environment activates JAK/STAT3 signaling to stimulate corneal inflammation. Inflammation and injury progression in infectious keratitis can also be modulated by JAK/STAT3 signaling. Furthermore, JAK/STAT3 signaling is involved in every stage of corneal repair after alkali burns, including acute inflammation, angiogenesis and fibrosis. Treatments modulating JAK/STAT3 signaling have shown promising results in attenuating corneal damage, indicating its potential as a novel therapeutic target. Thus, this review emphasizes the multiple roles of the JAK/STAT3 signaling pathway in common acquired corneal disorders and summarizes the current achievements of JAK/STAT3-targeting therapy to provide new insights into future applications.

Lipoxin A4 (LXA4) Reduces Alkali-Induced Corneal Inflammation and Neovascularization and Upregulates a Repair Transcriptome

PURPOSE

To investigate the anti-inflammatory and anti-angiogenic effects of the bioactive lipid mediator LXA4 on a rat model of severe corneal alkali injury.

METHODS

To induce a corneal alkali injury in the right eyes of anesthetized Sprague Dawley rats. They were injured with a Φ 4 mm filter paper disc soaked in 1 N NaOH placed on the center of the cornea. After injury, the rats were treated topically with LXA4 (65 ng/20 μL) or vehicle three times a day for 14 days. Corneal opacity, neovascularization (NV), and hyphema were recorded and evaluated in a blind manner. Pro-inflammatory cytokine expression and genes involved in cornel repair were assayed by RNA sequencing and capillary Western blot. Cornea cell infiltration and monocytes isolated from the blood were analyzed by immunofluorescence and by flow cytometry.

RESULTS

Topical treatment with LXA4 for two weeks significantly reduced corneal opacity, NV, and hyphema compared to the vehicle treatment. RNA-seq and Western blot results showed that LXA4 decreased the gene and protein expression of pro-inflammatory cytokines interleukin (IL)-1β and IL-6 and pro-angiogenic mediators matrix metalloproteinase (MMP)-9 and vascular endothelial growth factor (VEGFA). It also induces genes involved in keratinization and ErbB signaling and downregulates immune pathways to stimulate wound healing. Flow cytometry and immunohistochemistry showed significantly less infiltration of neutrophils in the corneas treated with LXA4 compared to vehicle treatment. It also revealed that LXA4 treatment increases the proportion of type 2 macrophages (M2) compared to M1 in blood-isolated monocytes.

CONCLUSIONS

LXA4 decreases corneal inflammation and NV induced by a strong alkali burn. Its mechanism of action includes inhibition of inflammatory leukocyte infiltration, reduction in cytokine release, suppression of angiogenic factors, and promotion of corneal repair gene expression and macrophage polarization in blood from alkali burn corneas. LXA4 has potential as a therapeutic candidate for severe corneal chemical injuries.

Research models of sulfur mustard- and nitrogen mustard-induced ocular injuries and potential therapeutics

Sulfur mustard (SM) is a notorious, bifunctional alkylating vesicant that was first used in warfare during World War I in 1917 and since then has been deployed in numerous skirmishes with its most recent documented use being during the Middle Eastern conflicts. Apart from its use in combat and terrorist activities, continual threat of accidental exposure from old stockpiles and improperly discarded munitions is ever present, especially to the innocent and unassuming civilian populations. SM can cause devastating injuries, depending on the dosage of SM exposure, route of exposure, as well as the physiological conditions of the individuals exposed. The most common routes of exposure are ocular, dermal, and exposure to the lungs and respiratory tissues through inhalation. Eyes are the most susceptible organ to SM-induced toxicities owing to their high moisture content and rapidly dividing cells. Additionally, ocular injury causes the most expeditious disablement of individuals even upon whole-body exposures. Therefore, it is imperative to understand the mechanisms underlying SM-induced ocular toxicity and design therapeutic interventions to prevent/mitigate ocular injuries. Ocular SM exposure may cause a wide range of symptoms such as inflammation, lacrimation, itching, dryness, photophobia, edema of the cornea/sclera/retina/iris, conjunctivitis, degradation of the corneal layer, fusion of two or more ocular layers, neovascularization, fibrosis, and temporary or permanent structural damage to one or more ocular layers. These symptoms may lead to vision impairments, resulting in partial or complete blindness that may be permanent. The highly toxic and exceedingly notorious nature of SM makes it a highly regulated chemical, requiring very expensive licensing, security, and safety requirements; thus, the more easily accessible analogue, nitrogen mustard (NM) that mimics SM-induced toxicity and injuries is employed in plethora of studies conducted in different animal models and culture systems. This review provides a comprehensive account of the injuries and symptoms that occur upon ocular SM exposures in human patients as well as studies in animal (in vivo, ex vivo) and cell (in vitro) models of SM and NM ocular exposures. Special emphasis has been laid on highlighting the strengths and lacunae in the research as well as the possible unexplored avenues of mechanisms underlying mustard-induced ocular injury that can be explored in future research endeavors. Furthermore, development of therapeutic interventions and targets of interest in the ocular system exposed to SM and NM, based on studies in human patients as well as in vivo, ex vivo, and in vitro models has been discussed in great depth, providing a valuable knowledge database to delineate pathways associated with vesicant-induced toxicity, and strategies/diagnostic tools against SM-induced toxicity.

Hypoxia-induced mesenchymal stem cells inhibit corneal fibroblast proliferation by regulating the WWP2/Notch1 axis

Aim: This study aimed to explore the role of hypoxic mesenchymal stem cells (MSCs) in corneal alkali burns and the underlying mechanism. Materials & methods: Rat corneal fibroblasts were incubated with IL-6, followed by treatment with hypoxic MSC supernatant. A rat corneal alkali burn model was implemented and processed with hypoxic MSCs. The associated factors were detected by corresponding methods. Results: Hypoxic MSCs reduced the Notch1 level and the proliferation of rat corneal fibroblasts. Hypoxic MSCs or WWP2 overexpression in MSCs enhanced ubiquitination of Notch1. WWP2 interacted with Notch1, and WWP2 silencing reversed the effects of the hypoxic MSCs. Hypoxic MSC treatment in vivo decreased the corneal neovascularization scores and opacity scores. Conclusion: Hypoxic MSCs inhibited inflammation and alleviated corneal injury in alkali burns via the WWP2/Notch1 axis.

Immunity and pain in the eye: focus on the ocular surface

Most ocular diseases are associated with pain. While pain has been generally considered a mere (deleterious) additional symptom, it is now emerging that it is a key modulator of innate/adaptive immunity. Because the cornea receives the highest nerve density of the entire body, it is an ideal site to demonstrate interactions between pain and the immune response. Indeed, most neuropeptides involved in pain generation are also potent regulators of innate and adaptive leukocyte physiology. On the other hand, most inflammatory cells can modulate the generation of ocular pain through release of specific mediators (cytokines, chemokines, growth factors, and lipid mediators). This review will discuss the reciprocal role(s) of ocular surface (and specifically: corneal) pain on the immune response of the eye. Finally, we will discuss the clinical implications of such reciprocal interactions in the context of highly prevalent corneal diseases.

Ocular Wnt/β-Catenin Pathway Inhibitor XAV939-Loaded Liposomes for Treating Alkali-Burned Corneal Wound and Neovascularization

Corneal wound involves a series of complex and coordinated physiological processes, leading to persistent epithelial defects and opacification. An obstacle in the treatment of ocular diseases is poor drug delivery and maintenance. In this study, we constructed a Wnt/β-catenin pathway inhibitor, XAV939-loaded liposome (XAV939 NPs), and revealed its anti-inflammatory and antiangiogenic effects. The XAV939 NPs possessed excellent biocompatibility in corneal epithelial cells and mouse corneas. In vitro corneal wound healing assays demonstrated their antiangiogenic effect, and LPS-induced expressions of pro-inflammatory genes of IL-1β, IL-6, and IL-17α were significantly suppressed by XAV939 NPs. In addition, the XAV939 NPs significantly ameliorated alkali-burned corneas with slight corneal opacity, reduced neovascularization, and faster recovery, which were attributed to the decreased gene expressions of angiogenic and inflammatory cytokines. The findings supported the potential of XAV939 NPs in ameliorating corneal wound and suppressing neovascularization, providing evidence for their clinical application in ocular vascular diseases.

Therapeutic contact lenses fabricated by hyaluronic acid and silver incorporated bovine serum albumin porous films for the treatment of alkali-burned corneal wound

Hyaluronic acid (HA) was covalently linked to the surface of bovine serum albumin/silver (BSA/Ag) porous films to fabricate a possible contact lens. The BSA/Ag/HA films showed favorable properties as contact lenses, including acceptable transparency, high water content, good hemocompatibility, non-cytotoxicity and antibacterial properties. The therapeutic potential of the BSA/Ag/HA films was evaluated on an alkali burn-induced corneal injury model on mice. The corneal healing rate was enhanced, the corneal opacification and neovascularization were lessened, and the inflammation response was reduced. The chemical cross-linking of HA on the films prolonged the retention time of HA on the corneal surface, thus enhanced the drug efficacy and improved the patient compliance, proving the high potential of BSA/Ag/HA films as contact lenses.

Protective roles of the TIR/BB-loop mimetic AS-1 in alkali-induced corneal neovascularization by inhibiting ERK phosphorylation

Hydrocinnamoyl-L-valylpyrrolidine (AS-1), a synthetic low-molecule mimetic of myeloid differentiation primary response gene 88 (MyD88), inhibits inflammation by disrupting the interaction between the interleukin-1 receptor (IL-1R) and MyD88. Here, we describe the effects of AS-1 on injury-induced increases in inflammation and neovascularization in mouse corneas. Mice were administered a subconjunctival injection of 8 μL AS-1 diluent before or after corneal alkali burn, followed by evaluation of corneal resurfacing and corneal neovascularization (CNV) by slit-lamp biomicroscopy and clinical assessment. Corneal inflammation was assessed by whole-mount CD45⁺ immunofluorescence staining, and corneal hemangiogenesis and lymphangiogenesis following injury were evaluated by immunostaining for the vascular markers isolectin B4 (IB4) and the lymphatic vascularized marker lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1), respectively. Additionally, corneal tissues were collected to determine the expression of 35 cytokines, and we detected activation of IL-1RI, MyD88, and mitogen-activated protein kinase (MAPK). The results showed that alkali conditions increased the number of CD45⁺ cells and expression of vascular endothelial growth factor (VEGF)-A, VEGF-C, and LYVE1 in corneas, with these levels decreased in the AS-1-treated group. Moreover, AS-1 effectively prevented alkali-induced cytokine production, blocked interactions between IL-1RI and MyD88, and inhibited MAPK activation post-alkali burn. These results indicated that AS-1 prevented alkali-induced corneal hemangiogenesis and lymphangiogenesis by blocking IL-1RI-MyD88 interaction, as well as extracellular signal-regulated kinase phosphorylation, and could be efficacious for the prevention and treatment of corneal alkali burn.

The Role of Inflammatory Cytokines in Neovascularization of Chemical Ocular Injury

Aim: Chemical injuries can potentially lead to the necrosis anterior segment of the eye, and cornea in particular. Inflammatory cytokines are the first factors produced after chemical ocular injuries. Inflammation via promoting the angiogenesis factor tries to implement the wound healing mechanism in the epithelial and stromal layer of the cornea. Methods: Narrative review.Results: In our review, we described the patterns of chemical injuries in the cornea and their molecular mechanisms associated with the expression of inflammatory cytokines. Moreover, the effects of inflammation signals on angiogenesis factors and CNV were explained. Conclusion: The contribution of inflammation and angiogenesis causes de novo formation of blood vessels that is known as the corneal neovascularization (CNV). The new vascularity interrupts cornea clarity and visual acuity. Inflammation also depleted the Limbal stem cells (LSCs) in the limbus causing the failure of normal corneal epithelial healing and conjunctivalization of the cornea.

Increased IL-6 and Potential IL-6 trans-signalling in the airways after an allergen challenge

BACKGROUND

In asthma, IL-6 is a potential cause of enhanced inflammation, tissue damage and airway dysfunction. IL-6 signalling is regulated by its receptor, which is composed of two proteins, IL-6R and GP130. In addition to their membrane form, these two proteins may be found as extracellular soluble forms. The interaction of IL-6 with soluble IL-6R (sIL-6R) can trigger IL-6 trans-signalling in cells lacking IL-6R. Conversely, the soluble form of GP130 (sGP130) competes with its membrane form to inhibit IL-6 trans-signalling.

OBJECTIVES

We aimed to analyse IL-6 trans-signalling proteins in the airways of subjects after an allergen challenge.

METHODS

We used a model of segmental bronchoprovocation with an allergen (SBP-Ag) in human subjects with allergy. Before and 48 h after SBP-Ag, bronchoalveolar lavages (BALs) allowed for the analysis of proteins in BAL fluids (BALFs) by ELISA, and membrane proteins on the surface of BAL cells by flow cytometry. In addition, we performed RNA sequencing (RNA-seq) and used proteomic data to further inform on the expression of the IL-6R subunits by eosinophils, bronchial epithelial cells and lung fibroblasts. Finally, we measured the effect of IL-6 trans-signalling on bronchial fibroblasts, in vitro.

RESULTS

IL-6, sIL-6R, sGP130 and the molar ratio of sIL-6R/sGP130 increased in the airways after SBP-Ag, suggesting the potential for enhanced IL-6 trans-signalling activity. BAL lymphocytes, monocytes and eosinophils displayed IL-6R on their surface and were all possible providers of sIL-6R, whereas GP130 was highly expressed in bronchial epithelial cells and lung fibroblasts. Finally, bronchial fibroblasts activated by IL-6 trans-signalling produced enhanced amounts of the chemokine, MCP-1 (CCL2).

CONCLUSION AND CLINICAL RELEVANCE

After a bronchial allergen challenge, we found augmentation of the elements of IL-6 trans-signalling. Allergen-induced IL-6 trans-signalling activity can activate fibroblasts to produce chemokines that can further enhance inflammation and lung dysfunction.

Acetylsalicylic Acid Promotes Corneal Epithelium Migration by Regulating Neutrophil Extracellular Traps in Alkali Burn

Neutrophils are the first cells to migrate into the cornea in response to alkali burns, and excessive neutrophil infiltration is associated with inflammatory injury and a poorer prognosis. In an effort to understand the mechanisms underlying the inflammation mediated by neutrophils after alkali burns, we examined the role of alkali-activated neutrophils on human corneal epithelial cells (HCEs) proliferation and migration, as well as the effects of acetylsalicylic acid (ASA) and dexamethasone (DXM) on NETosis. We stimulated human neutrophils with sodium hydroxide (NaOH) and observed dose- and time-dependent neutrophil extracellular traps (NETs) formation. We also observed that ASA, but not DXM, significantly inhibited NaOH-induced NETosis. Furthermore, the activation of nuclear factor (NF)-κB, but not the production of reactive oxygen species, was involved in ASA-regulated NETosis. Moreover, NETs were found to be involved in alkali-activated neutrophils (ANs) induced neutrophil-HCE adhesion. ANs enhanced HCEs proliferation via phagocytosis. Meanwhile, ANs inhibited HCEs migration through the release of NETs, which was partially rescued by 5 mM ASA. In conclusion, ANs may interfere with HCEs proliferation and migration by phagocytosis and NETs formation, respectively. ASA may enhance HCEs migration by decreasing NETs formation through inhibition of NF-κB activation and could be a promising strategy for improving the prognosis of corneal alkali burns.

Modulating Contact Lens Discomfort With Anti-Inflammatory Approaches: A Randomized Controlled Trial

Purpose

To assess the efficacy of anti-inflammatory approaches, comprising a topical corticosteroid and omega-3 supplements, for modulating the inflammatory overlay associated with contact lens discomfort (CLD).

Methods

This randomized controlled trial involved 72 adults with CLD, randomized (1:1:1:1) to one of the following: placebo (oral olive oil), oral fish oil (900 mg/d eicosapentaenoic acid [EPA] + 600 mg/d docosohexaenoic acid [DHA]), oral combined fish+flaxseed oils (900 mg/d EPA + 600 mg/d DHA + 900 mg/d alpha-linolenic acid), or omega-3 eye-drops (0.025% EPA + 0.0025% DHA four times per day [qid]) for 12 weeks, with visits at baseline, weeks 4 and 12. At week 12, participants who received placebo were assigned a low-potency corticosteroid (fluorometholone [FML] 0.1%, drops, three times per day [tid]) for 2 weeks (week 14).

Results

Sixty-five participants completed the primary endpoint. At week 12, contact lens dry-eye questionnaire (CLDEQ-8) score was reduced from baseline with oral fish oil (-7.3 ± 0.8 units, n = 17, P < 0.05), compared with placebo (-3.5 ± 0.9 units, n = 16). FML produced significant reductions in tear IL-17A (-71.1 ± 14.3%, n = 12) and IL-6 (-47.6 ± 17.5%, n = 12, P < 0.05) relative to its baseline (week 12). At week 12, tear IL-17A levels were reduced from baseline in the oral fish oil (-63.2 ± 12.8%, n = 12, P < 0.05) and topical omega-3 (-76.2 ± 10.8%, n = 10, P < 0.05) groups, compared with placebo (-3.8 ± 12.7%, n = 12). Tear IL-6 was reduced with all omega-3 interventions, relative to placebo (P < 0.05) at week 12.

Conclusions

CLD was attenuated by oral long-chain omega-3 supplementation for 12 weeks. Acute (2 week) topical corticosteroids and longer-term (12 week) omega-3 supplementation reduced tear levels of the proinflammatory cytokines IL-17A and IL-6, demonstrating parallels in modulating ocular inflammation with these approaches.

Acute tobacco smoke exposure exacerbates the inflammatory response to corneal wounds in mice via the sympathetic nervous system

Exposure to tobacco smoke is a major public health concern that can also affect ophthalmic health. Based on previous work demonstrating the important role of the sympathetic nervous system (SNS) in corneal wound repair, we postulated that acute tobacco smoke exposure (ATSE) may act through the SNS in the impairment of corneal wound repair. Here we find that ATSE rapidly increases the markers of inflammatory response in normal corneal limbi. After an abrasion injury, ATSE exaggerates inflammation, impairs wound repair, and enhances the expression of nuclear factor-κB (NF-κB) and inflammatory molecules such as interleukin-6 (IL-6) and IL-17. We find that chemical SNS sympathectomy, local adrenergic receptor antagonism, NF-κB1 inactivation, and IL-6/IL-17A neutralization can all independently attenuate ATSE-induced excessive inflammatory responses and alleviate their impairment of the healing process. These findings highlight that the SNS may represent a major molecular sensor and mediator of ATSE-induced inflammation.

Interleukin-6 participation in pathology of ocular diseases

Interleukin-6 (IL-6) is a multifunctional cytokine that affects a variety of cells in the body such as osteoclasts, hepatocytes, endothelial cells, epithelial cells, white and red blood cells and etc. Elevated levels of IL-6 have been detected in many ocular diseases. Studies show that IL-6 has a major role in the pathology of glaucoma, CRVO, macular edema, ocular neovascularization, posterior capsule opacity formation, keratitis, dry eye disease, allergic eye disease, ocular autoimmune disease, corneal chemical burn, ocular inflammation and so on. IL-6 does its effects through the classic or trans-signal pathways in cells. Blocking of IL-6 signal pathways via Tocilizumab or other chemicals and therapeutics will help to overcome complications related to ocular diseases.

The Blockade of IL6 Counterparts the Osmolar Stress-Induced Apoptosis in Human Conjunctival Epithelial Cells

To determine the effect of hyperosmolarity on cell survival/apoptosis of conjunctival epithelial cells and evaluate the possible role of IL6, Wong-Kilbourne derivative of Chang conjunctival cell line (WKD) was used in this study. Confluent cells were incubated under different osmolarity (290 mOsm and 500 mOsm) with or without neutralizing IL6 antibody (50 ng/mL). The expression of IL6 level was measured in the supernatant of each conditioned medium. Cell viability/apoptosis assay was performed using Annexin V/Propidium Iodide (PI) and Cell Counting Kit-8 (CCK-8). Western blot was conducted to measure the abundance of apoptotic markers and IL6 related downstream signaling pathway. The concentration of IL6 showed time-dependent increase in cells treated with 500 mOsm. Although apoptosis of WKD cell is increased in treated 500 mOsm for 24 h, apoptosis reduced in WKD cell treated 500 mOsm with anti-IL6 for 24 h. Anti-IL6 inhibited the activation of JAK-STAT signaling pathway, which was induced by hyperosmolarity. Hyperosmolar condition induced apoptosis in conjunctival epithelial cells, along with increase of IL6 production. IL6 neutralizing antibody inhibited apoptosis and JAK-STAT signaling in hyperosmolar condition. These findings suggested that IL6 may be involved in apoptotic change and in hyperosmolarity.

MK2 inhibitor reduces alkali burn-induced inflammation in rat cornea

MK2 activation by p38 MAPK selectively induces inflammation in various diseases. We determined if a MK2 inhibitor (MK2i), improves cornea wound healing by inhibiting inflammation caused by burning rat corneas with alkali. Our study, for the first time, demonstrated that MK2i inhibited alkali burn-induced MK2 activation as well as rises in inflammation based on: a) blunting rises in inflammatory index, inflammatory cell infiltration, ED1⁺ macrophage and PMN⁺ neutrophil infiltration; b) suppressing IL-6 and IL-1β gene expression along with those of macrophage inflammatory protein-1α (MIP-1α), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1); c) reducing angiogenic gene expression levels and neovascularization (NV) whereas anti-angiogenic PEDF levels increased. In addition, this study found that MK2i did not affect human corneal epithelial cell (HCEC) proliferation and migration and had no detectable side effects on ocular surface integrity. Taken together, MK2i selectively inhibited alkali burn-induced corneal inflammation by blocking MK2 activation, these effects have clinical relevance in the treatment of inflammation related ocular surface diseases.

Research on mouse model of grade II corneal alkali burn

AIM

To choose appropriate concentration of sodium hydroxide (NaOH) solution to establish a stable and consistent corneal alkali burn mouse model in grade II.

METHODS

The mice (n=60) were randomly divided into four groups and 15 mice each group. Corneal alkali burns were induced by placing circle filter paper soaked with NaOH solutions on the right central cornea for 30s. The concentrations of NaOH solutions of groups A, B, C, and D were 0.1 mol/L, 0.15 mol/L, 0.2 mol/L, and 1.0 mol/L respectively. Then these corneas were irrigated with 20 mL physiological saline (0.9% NaCl). On day 7 postburn, slit lamp microscope was used to observe corneal opacity, corneal epithelial sodium fluorescein staining positive rate, incidence of corneal ulcer and corneal neovascularization, meanwhile pictures of the anterior eyes were taken. Cirrus spectral domain optical coherence tomography was used to scan cornea to observe corneal epithelial defect and corneal ulcer.

RESULTS

Corneal opacity scores (x±s) were not significantly different between the group A and group B (P=0.097). Incidence of corneal ulcer in group B was significantly higher than that in group A (P=0.035). Incidence of corneal ulcer and perforation rate in group B was lower than that in group C. Group C and D had corneal neovascularization, and incidence of corneal neovascularization in group D was significantly higher than that in group C (P=0.000).

CONCLUSION

Using 0.15 mol/L NaOH can establish grade II mouse model of corneal alkali burns.

Assessment of therapeutic options for reducing alkali burn-induced corneal neovascularization and inflammation

This article aims to review and provide the current knowledge of the possibilities of topical treatment of corneal neovascularization due to alkali burns, evidenced by laboratory experiments, in vitro studies, and clinical trials published in the specialized literature. Authors present clinically relevant treatment of corneal neovascularization used in clinical practice, potential antiangiogenic topical therapeutics against corneal neovascularization, which are under investigation, and anti-angiogenic gene-therapy.

Anti-inflammatory effect of topical administration of tofacitinib on corneal inflammation

We evaluated an anti-inflammatory effect of topical administration of tofacitinib, janus kinase (JAK) blocker, on corneal inflammation. Topical instillation of either tofacitinib or PBS was applied after wounding BALB/c mice corneas with alkali burn. Topical instillation was performed until day 14 after injury and injured eye was analyzed. The vascularized area in the alkali burned cornea was significantly reduced in the tofacitinib group compared with that in the PBS group. The immunoreactivity of Gr-1, F4/80, IFN-γ, and phosphorylated STAT(signal transducer and activator of transcription)1 in corneal stroma was diminished significantly in the tofacitinib group. Using laser capture microdissection system and quantitative PCR array analysis, the expression levels of CXCL9, CXCL5, CCL7, CCL2, MMP(matrix metalloproteinase)-9, and STAT1 in corneal stroma were down-regulated in the tofacitinib group. In in vitro study, human fibroblast pretreated by IFN-γ showed phosphorylation of STAT1, and this phosphorylation was down-regulated by adding tofacitinib to the culture medium. These results indicate the topical application of JAK inhibitor causes down-regulation of JAK- or IFN-γ-related molecules. Therefore, we deduce that application of JAK inhibitor for topical instillation may contribute to the treatment of corneal inflammation.

Expression of IL-8, IL-6 and IL-1β in tears as a main characteristic of the immune response in human microbial keratitis

Corneal infections are frequent and potentially vision-threatening diseases, and despite the significance of the immunological response in animal models of microbial keratitis (MK), it remains unclear in humans. The aim of this study was to describe the cytokine profile of tears in patients with MK. Characteristics of ocular lesions such as size of the epithelial defect, stromal infiltration, and hypopyon were analyzed. Immunological evaluation included determination of interleukine (IL)-1β, IL-6, IL-8, IL-10, IL-12 and tumor necrosis factor (TNF)-α in tear samples obtained from infected eyes of 28 patients with MK and compared with their contralateral non-infected eyes. Additionally, frequency of CD4⁺, CD8⁺, CD19⁺ and CD3⁻CD56⁺ cells was also determined in peripheral blood mononuclear cells in patients with MK, and compared with 48 healthy controls. Non-significant differences were observed in the size of the epithelial defect, stromal infiltration, and hypopyon. Nevertheless, we found an immunological profile apparently related to MK etiology. IL-8 > IL-6 in patients with bacterial keratitis; IL-8 > IL-6 > IL-1β and increased frequency of circulating CD3⁻CD56⁺ NK cells in patients with gram-negative keratitis; and IL-8 = IL-6 > IL-1β in patients with fungal keratitis. Characterization of tear cytokines from patients with MK could aid our understanding of the immune pathophysiological mechanisms underlying corneal damage in humans.

Correlation between human tear cytokine levels and cellular corneal changes in patients with bacterial keratitis by in vivo confocal microscopy

PURPOSE

We investigated bilateral tear cytokine levels in patients with unilateral bacterial keratitis (BK) as associated with in vivo confocal microscopic (IVCM) alterations in corneal nerves and dendritiform immune cells (DCs).

METHODS

A total of 54 (13 BK, 13 contralateral, 28 healthy controls) tear samples was collected prospectively and analyzed by multiplex microbeads assay. The IVCM of the central cornea was performed on the same day, and assessed for corneal nerve and DC alterations.

RESULTS

Interleukin-1β, IL-6, and IL-8 were significantly elevated only in affected eyes (66.6 ± 26.8, 7174 ± 2430, and 810 ± 315 ρg/mL, respectively; P = 0.04, P < 0.001, and P < 0.001, respectively), compared to healthy controls (13.0 ± 4.0, 171.8 ± 32.1, and 56.5 ± 33.8 ρg/mL). Levels of chemokine ligand 2 (CCL-2), IL-10, and IL-17a were elevated only in contralateral eyes (813 ± 478, 86.7 ± 38.3, and 3350 ± 881 ρg/mL, respectively; P = 0.02, P = 0.01, and P = 0.04, respectively), compared to controls (73.7 ± 25.3, 17.5 ± 4.9, and 1350 ± 337 ρg/mL). Triggering receptor expressed on myeloid cells (TREM)-1 was significantly elevated in affected (551 ± 231 ρg/mL, P = 0.02) and contralateral unaffected (545 ± 298 ρg/mL, P = 0.03) eyes compared to controls (31.3 ± 12.4 ρg/mL). The density of DCs was significantly increased in affected (226.9 ± 37.3 cells/mm(2), P < 0.001) and unaffected (122.3 ± 23.7 cells/mm(2), P < 0.001) eyes compared to controls (22.7 ± 5.9 cells/mm(2)). Sub-basal nerve density significantly decreased in affected (3337 ± 1615 μm/mm(2), P < 0.001) and contralateral (13,230 ± 1635 μm/mm(2), P < 0.001) eyes compared to controls (21,200 ± 545 μm/mm(2)). Levels of IL-1β, IL-6, and IL-8 were significantly correlated with DC density (R = 0.40, R = 0.55, and R = 0.31, all P < 0.02) and nerve density (R = -0.30, R = -0.53, and R = -0.39, all P < 0.01).

CONCLUSIONS

Proinflammatory tear cytokines are elevated bilaterally in patients with unilateral BK, and are correlated strongly with alterations in DCs and nerve density as detected by IVCM.

Inhibitory effect of sub-conjunctival tocilizumab on alkali burn induced corneal neovascularization in rats

BACKGROUND

To evaluate the effects of sub-conjunctivally applied interleukin-6 receptor (IL-6R) antibody (tocilizumab) on alkali burn induced corneal neovascularization (CNV) in rats.

METHODS

Alkali burn induced corneal neovascularization was created in 24 right eyes of 24 rats. The rats were then randomized into 2 groups. Group 1 received sub-conjunctival injection of 4 mg/0.2 ml tocilizumab and Group 2 received sub-conjunctival injection of 0.2 ml normal saline at the 5th day of alkali burn. The corneal surface area invaded with neovascular vessels were calculated on photographs. The rats were sacrificed and the corneas were excised at the15th day. The corneal specimens were stained with hemotoxylin-eosin to evaluate tissue morphology and with Willebrand factor (vWF) to evaluate microvascular structures immunohistochemically. Vascular endothelial growth factor (VEGF) expression was analyzed by ELISA.

RESULTS

The percent area of CNV was 26.9% in Group 1 and 56.5% in Group 2 (p < 0.001). The histological evaluation showed that the corneal structures were not visibly altered by sub-conjuntival tocilizumab injection. Group 1 showed significantly lower corneal inflammation score than Group 2 (p < 0.001). The number of vessels stained with vWF were significantly higher in Group 2 than Group 1 (15.23 and 5.46, respectively; p < 0.001). ELISA analyses showed that corneal VEGF levels were significantly lower in Group 1 compared to Group 2 (p = 0.013) CONCLUSION: The present data demonstrated first time the beneficial effects of sub-conjunctival tocilizumab on decreasing CNV in alkali burn model of the rat cornea. Further studies are warranted to confirm these findings for the clinical application.

Junctional adhesion molecule-A regulates vascular endothelial growth factor receptor-2 signaling-dependent mouse corneal wound healing

Inflammation and angiogenesis are integral parts of wound healing. However, excessive and persistent wound-induced inflammation and angiogenesis in an avascular tissue such as the cornea may be associated with scarring and visual impairment. Junctional adhesion molecule A (Jam-A) is a tight junction protein that regulates leukocyte transmigration as well as fibroblast growth factor-2 (FGF-2)-induced angiogenesis. However its function in wound-induced inflammation and angiogenesis is still unknown. In this study, we report spontaneous corneal opacity in Jam-A deficient mice associated with inflammation, angiogenesis and the presence of myofibroblasts. Since wounds and/or corneal infections cause corneal opacities, we tested the role of Jam-A in wound-induced inflammation, angiogenesis and scarring by subjecting Jam-A deficient mice to full thickness corneal wounding. Analysis of these wounds demonstrated increased inflammation, angiogenesis, and increased number of myofibroblasts thereby indicating that Jam-A regulates the wound-healing response by controlling wound-induced inflammation, angiogenesis and scarring in the cornea. These effects were not due to inflammation alone since the inflammation-induced wound-healing response in Jam-A deficient mice was similar to wild type mice. In order to determine the molecular mechanism associated with the observed aberrant corneal wound healing in Jam-A deficient mice, we assessed the expression of the components of vascular endothelial growth factor A (VEGF-A)/vascular endothelial growth factor receptor- 2(VEGFR-2) signaling pathway. Interestingly, we observed increased levels of VEGF-A mRNA in Jam-A deficient eyes. We also observed nuclear localization of phosphorylated SMAD3 (pSMAD3) indicative of TGFβ pathway activation in the Jam-A deficient eyes. Furthermore the increased wound-induced corneal inflammation, angiogenesis, and scarring in Jam-A deficient mice was attenuated by treatment with DC101, an anti-vascular endothelial growth factor receptor-2 (VEGFR-2) antibody. Our results suggest that in the absence of Jam-A, the VEGF-A/VEGFR-2 pathway is upregulated, thereby augmenting wound induced corneal inflammation, angiogenesis, and myofibroblast accumulation leading to scarring.