Pharmacological treatment strategies of pterygium: Drugs, biologics, and novel natural products.

Pterygium is a fibrovascular tissue growth invading the cornea. Adjunctive treatment post-surgery includes conventional immunosuppressants as well as antiviral drugs. The use of large- and small-molecule antivascular endothelial growth factor (VEGF) agents remains an integral part of pterygium treatment as well as other neovascular conditions of the eye. Naturally occurring polyphenolic compounds have favorable characteristics for treating neovascular and inflammatory eye conditions, including good efficacy, stability, cost-effectiveness, and the versatility of their chemical synthesis. In this review, we discuss pharmacological treatments of pterygium. Natural products, such curcumin, ellagic acid, and chalcones, are reviewed, with emphasis on their potential as future pterygium treatments.

Inhibition of Aberrant α(1,2)-Fucosylation at Ocular Surface Ameliorates Dry Eye Disease.

Fucosylation is involved in a wide range of biological processes from cellular adhesion to immune regulation. Although the upregulation of fucosylated glycans was reported in diseased corneas, its implication in ocular surface disorders remains largely unknown. In this study, we analyzed the expression of a fucosylated glycan on the ocular surface in two mouse models of dry eye disease (DED), the NOD.B10.H2b mouse model and the environmental desiccating stress model. We furthermore investigated the effects of aberrant fucosylation inhibition on the ocular surface and DED. Results demonstrated that the level of type 2 H antigen, an α(1,2)-fucosylated glycan, was highly increased in the cornea and conjunctiva both in NOD.B10.H2b mice and in BALB/c mice subjected to desiccating stress. Inhibition of α(1,2)-fucosylation by 2-deoxy-D-galactose (2-D-gal) reduced corneal epithelial defects and increased tear production in both DED models. Moreover, 2-D-gal treatment suppressed the levels of inflammatory cytokines in the ocular surface and the percentages of IFN-γ+CD4+ cells in draining lymph nodes, whereas it did not affect the number of conjunctival goblet cells, the MUC5AC level or the meibomian gland area. Together, the findings indicate that aberrant fucosylation underlies the pathogenesis of DED and may be a novel target for DED therapy.

How goblet cells respond to dry eye: adaptive and pathological roles of voltage-gated calcium channels and P2X7 purinoceptors.

Dry eye is a common sight-impairing, painful disorder characterized by disruption of the preocular tear film, whose integrity is required for ~70% of the eye's refractive power. A universal feature of clinical dry eye is hyperosmolarity of the tears resulting from their accelerated evaporation due to dysfunction of tear- and oil-producing ocular glands. A key adaptive response to dryness/hyperosmolarity is release of tear-stabilizing mucin by conjunctival goblet cells. Yet the mechanisms mediating this response to hyperosmolarity remain poorly understood. In this study of freshly excised rat conjunctiva, perforated-patch recordings revealed that during sustained hyperosmolarity, the development of a nonspecific cation (NSC) conductance depolarizes the goblet cells to a near-optimal voltage for the tonic activation of their voltage-gated calcium channels (VGCCs). In turn, as demonstrated by high-resolution membrane capacitance measurements, VGCC activation boosts the exocytotic response of conjunctival goblet cells to neural input. However, over time, VGCC activation also increases the vulnerability of these cells to the lethality of hyperosmolarity. Viability assays further revealed that hyperosmotic-induced goblet cell death is critically dependent on P2X7 receptor channels. Similar to the yin-yang impact of VGCCs on goblet cell physiology and pathobiology, P2X7 activation not only compromises goblet cell viability but also enhances exocytotic activity. Thus, the NSC/VGCC and P2X7 purinoceptor pathways are components of a previously unappreciated high-gain/high-risk adaptive strategy to combat ocular dryness. These pathways boost release of tear-stabilizing mucin at the risk of jeopardizing the viability of the conjunctival goblet cells, whose loss is a histopathological hallmark of irreversible mucin-deficient dry eye.

The Potential Inhibitory Effects of miR-19b on Ocular Inflammation are Mediated Upstream of the JAK/STAT Pathway in a Murine Model of Allergic Conjunctivitis.

Purpose: Thymic stromal lymphopoietin (TSLP) is a pro-allergic cytokine that initiates allergic inflammatory reaction between epithelial and dendritic cells (DCs). miR-19b was reported to suppress TSLP expression. The present study aimed to examine miR-19b expression, regulation, and function in allergic conjunctivitis (AC). Methods: A murine model of experimental AC was induced in BALB/c mice by short ragweed pollen. The serum, eye balls, conjunctiva, and cervical lymph nodes (CLN) were used for the study. Gene expression was determined by RT-PCR, whereas protein production and activation were evaluated by immunostaining, ELISA, and Western blotting. Results: In the murine AC model, miR-19b was aberrantly downregulated, whereas the levels of TSLP and p-STAT3, as well as the number of CD11c+ pSTAT3+ DCs were increased. Moreover, Th2 inflammatory cytokine expression was significantly increased. These severe phenotypes could be counteracted by either applying exogenous miR-19b mimic microRNAs or the JAK/STAT inhibitor CYT387. Moreover, overexpression of miR-19b repressed p-STAT3 expression and the number of CD11c+ cells in AC eye and CLN tissues. Conclusions: These findings suggested that miR-19b reduced ocular surface inflammation by inhibiting Stat3 signaling via TSLP downregulation in a murine AC model. Moreover, the present study further demonstrated the clinical potential of applying miR-19b and anti-JAK/STAT therapies in the treatment of AC.

A Mechanism Study of Electroacupuncture for Dry Eye Syndrome by Targeting Conjunctival Cytokine Expressions.

Aim: To discuss the immunological mechanism in electroacupuncture (EA) treatment of dry eye syndrome (DES) by targeting the changes in conjunctival cytokine expression profile.Method: Eligible DES patients were randomized into an EA group (EAG) or an acupuncture group (AG). The ocular surface disease index (OSDI), amount of tear production, and tear film break-up time (BUT) were observed to evaluate the efficacy. Conjunctival cells were collected from both effective and invalid cases to observe the expressions of cytokines by protein microarray. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used for functional cluster and signaling pathway analysis of the differentially expressed proteins. Enzyme-linked immunosorbent assay (ELISA) was used to verify the specific differential proteins.Result: After treatment, OSDI dropped and BUT extended in both groups, and the tear production increased only in the EAG (all P < .01). Compared with the AG, the improvement in tear production was more significant in the EAG (P < .01). There were 17 differentially expressed conjunctival cytokines between the effective and invalid cases in the EAG, and those expressed higher than the limit of detection (LOD) included monocyte chemoattractant protein 1 (MCP-1), macrophage colony-stimulating factor (M-CSF), regulated on activation in normal T-cell expressed and secreted (RANTES) and tissue inhibitor of metalloproteinases 1 (TIMP-1). GO analysis showed that the differential cytokines were mainly involved in cellular interaction, signaling pathways and reactions to stimuli. KEGG analysis revealed that the signaling pathways of these cytokines were mainly responsible for interactions between cytokines or between cytokines and their receptors, such as Jak-STAT signaling pathway, chemokine signaling pathway, and tumor necrosis factor signaling pathway.Conclusion: EA can effectively treat DES by improving the symptoms, increasing tear secretion and extending BUT, which is possibly related to its regulation on the conjunctival cytokine expressions.

Therapeutic efficacy of intense pulsed light in patients with refractory meibomian gland dysfunction.

PURPOSE: To evaluate the efficacy and safety of intense pulsed light (IPL) combined with meibomian gland expression (MGX) for treatment of refractory meibomian gland dysfunction (MGD). METHODS: Ninety eyes of 45 patients were randomly assigned to receive either the combination of IPL and MGX or MGX alone (control). Each eye underwent eight treatment sessions at 3-week intervals. Parameters were evaluated before and during treatment as well as at 3-11 weeks after the last treatment session. Measured parameters included the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire score, noninvasive breakup time (NIBUT), fluorescein breakup time (BUT), lipid layer grade, lipid layer thickness (LLT), lid margin abnormalities, corneal and conjunctival fluorescein staining (CFS) score, meibum grade, and meiboscore. RESULTS: A significant improvement in lipid layer grade was apparent in the IPL-MGX group from 6 to 32 weeks after treatment onset (adjusted P < 0.001) but was not observed in the control group. The IPL-MGX group also showed significant improvements in LLT, NIBUT, BUT, lid margin abnormalities, and meibum grade compared with the control group at 24 and 32 weeks (adjusted P < 0.001) as well as significant improvements in the SPEED score at 32 weeks (adjusted P = 0.044) and in CFS score at 24 (adjusted P = 0.015) and 32 (adjusted P = 0.006) weeks. CONCLUSIONS: The combination of IPL and MGX improved homeostasis of the tear film and ameliorated ocular symptoms in patients with refractory MGD and is thus a promising modality for treatment of this condition.

Multicenter Study of Intense Pulsed Light Therapy for Patients With Refractory Meibomian Gland Dysfunction.

PURPOSE: To evaluate the efficacy of intense pulsed light (IPL) therapy combined with meibomian gland expression (MGX) for refractory meibomian gland dysfunction (MGD) in a prospective study conducted at 3 sites in Japan. METHODS: Patients with refractory obstructive MGD were enrolled and underwent 4 to 8 IPL-MGX treatment sessions at 3-week intervals. Clinical assessment included the Standard Patient Evaluation of Eye Dryness questionnaire; noninvasive breakup time of the tear film and interferometric fringe pattern as determined by tear interferometry; lid margin abnormalities, fluorescein breakup time of the tear film, corneal and conjunctival fluorescein staining (CFS), and meibum grade as evaluated with a slit-lamp microscope; meibomian gland morphology (meiboscore); and tear production as measured by the Schirmer test without anesthesia. RESULTS: Sixty-two eyes of 31 patients (17 women, 14 men; mean age ± SD, 47.6 ± 16.8 years) were enrolled. The Standard Patient Evaluation of Eye Dryness score (P < 0.001), noninvasive breakup time (P < 0.001), and interferometric fringe pattern (P < 0.001) were significantly improved after therapy, with 74% of eyes showing a change in the interferometric fringe pattern from 1 characteristic of lipid deficiency to the normal condition. Meibum grade, lid margin abnormality scores, fluorescein breakup time, and CFS were also significantly improved (P < 0.001, P < 0.001, P < 0.001, and P = 0.002, respectively) after treatment, whereas the meiboscore and Schirmer test value remained unchanged. CONCLUSIONS: IPL-MGX ameliorated symptoms and improved the condition of the tear film in patients with refractory MGD and is therefore a promising treatment option for this disorder.

Evaluation of galectin-1 and galectin-3 as prospective biomarkers in keratoconus.

AIMS: To evaluate the expression of ß-galactoside-binding proteins galectin (Gal)-1 and Gal-3 in patients with keratoconus (KC) and postcorneal collagen cross-linking (CXL) treatment in vitro. METHODS: Tear fluid, cornea samples and conjunctival impression cytology specimens from control and KC patients were used to evaluate Gal-1 and Gal-3 expressions. Primary keratocytes were isolated by collagenase digestion from surgically removed corneas of five normal or KC human corneal buttons and cultured in Dulbecco's modified eagle medium/Ham's F12 medium supplemented with 2% fetal bovine serum. These cells were evaluated under two experimental conditions: control and submitted to the application of ultraviolet A light and riboflavin 0.1% (CXL) for 30 min. RESULTS: Patients with KC displayed increased levels of Gal-1 and Gal-3 in conjunctival epithelial cells compared with control. Furthermore, KC corneas were associated with intense expression of Gal-1 in the stroma, released by keratocytes. Ultrastructural analysis of keratocytes showed a marked increase of endogenous Gal-3 levels, but not Gal-1, in KC. In vitro, CXL induced significant release of Gal-1 in keratocyte supernatants (116±18 ng/mL, P<0.05) and decreased inflammatory biomarkers as interleukin (IL)-6, IL-8, matrix metalloproteinase (MMP)-2 and MMP-9. Gal-3 levels were not detected in the keratocyte supernatants. CONCLUSION: Gal-1 and Gal-3 represent new interesting KC biomarkers as revealed by their different expression patterns in KC and control corneal samples. CXL has an immunosuppressive effect on keratocytes by reducing the release of cytokines and MMPs and increased expression of anti-inflammatory protein Gal-1.

Anti-angiogenic effect of hexahydrocurcumin in rat corneal neovascularization.

AIM: This study was to investigate the anti-angiogenic effect of hexahydrocurcumin (HHC) to evaluate gene (p-basic fibroblast growth factor (bFGF)-SAINT-18 & p-vascular endothelial growth factor (VEGF)-SAINT-18 complex)-induced corneal neovascularization (CorNV) in rats. METHODS: CorNV was induced in 24 eyes of 24 rats. Four groups (Group A: 0 µg, B: 0.01 µg, C: 0.1 µg, and D: 1 µg) of HHC were prepared and implanted into the rat subconjunctival substantia propria 1.5 mm from the limbus at temporal side. The 1 µg of p-bFGF-SAINT-18 & p-VEGF-SAINT-18 complex were prepared and implanted into the rat corneal stroma 1.5 mm from the limbus at the same side. Inhibition of CorNV was observed and quantified from day 1 to day 60. bFGF and VEGF protein expression were analyzed by biomicroscopic examination, western blot analysis, and immunohistochemistry. RESULTS: Subconjunctival injection by 1 µg HHC successfully inhibited gene-induced CorNV in rats. bFGF and VEGF protein expression were reduced after 6 days. Meanwhile, the reduction of HLA-DR expression was detected. CONCLUSIONS: Our study showed that the HHC might provide an important anti-angiogenesis factor to inhibit CorNV development at the corneal experimental angiogenesis model.

Ocular Effects of Sulfur Mustard and Therapeutic Approaches.

Sulfur mustard (SM) is a strong blistering, highly reactive, lipophilic chemical war agent that causes injury in different organs including the skin, eyes, and respiratory tract. The Eyes are especially susceptible to the consequences of SM poisoning because of the aqueous and mucosal nature of conjunctiva and cornea. DNA alkylation and depletion of glutathione, are the most important mechanisms of SM action in the eye injuries. Acute clinical symptoms are including decrease in visual acuity, dryness, photophobia, blepharospasm, conjunctivitis, and complaints of foreign body sensation and soreness that gradually progress to severe ocular pain. Corneal abrasions, ulcerations, vesication, and perforations are common corneal consequences in SM injured victims. Appearance of chronic symptoms has been reported as chronic inflammation of the corneal and conjunctival vasculature, ischemia, lipid and cholesterol deposition, scarring in cornea, corneal thinning, opacification and perforation of the cornea, limbal stem cell deficiency (LSCD), and neovascularization. Different medical and surgical protocols have been documented in the management of SM-induced ocular injuries, including preservative-free artificial tears, topical steroids and antibiotic, mydriatic, antiglaucoma drops, therapeutic contact lenses, dark glasses and punctal plugs/cauterization, N-acetylcysteine, tarsorrhaphy, amniotic membrane transplantation, stem cell transplantation, and corneal transplantation. New drugs such as resolvin E1, topical form of essential fatty acids, thymosin ß4, 43 amino-acid polypeptides, topical form of curcumin, newly formulated artificial tears, diquafosol, rebamipide, tretinoin, and oral uridineseems to be beneficial in the management of ocular lesion associated with sulfur mustard poisoning. Further studies are needed to approve these drugs in SM victims. J. Cell. Biochem. 118: 3549-3560, 2017. © 2017 Wiley Periodicals, Inc.

Pollen/TLR4 Innate Immunity Signaling Initiates IL-33/ST2/Th2 Pathways in Allergic Inflammation.

Innate immunity has been extended to respond environmental pathogen other than microbial components. Here we explore a novel pollen/TLR4 innate immunity in allergic inflammation. In experimental allergic conjunctivitis induced by short ragweed (SRW) pollen, typical allergic signs, stimulated IL-33/ST2 signaling and overproduced Th2 cytokine were observed in ocular surface, cervical lymph nodes and isolated CD4+ T cells of BALB/c mice. These clinical, cellular and molecular changes were significantly reduced/eliminated in TLR4 deficient (Tlr4-d) or MyD88 knockout (MyD88-/-) mice. Aqueous SRW extract (SRWe) directly stimulated IL-33 mRNA and protein expression by corneal epithelium and conjunctiva in wild type, but not in Tlr4-d or MyD88-/- mice with topical challenge. Furthermore, SRWe-stimulated IL-33 production was blocked by TLR4 antibody and NF-kB inhibitor in mouse and human corneal epithelial cells. These findings for the first time uncovered a novel mechanism by which SRW pollen initiates TLR4-dependent IL-33/ST2 signaling that triggers Th2-dominant allergic inflammation.

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

CONTEXT: The roots of Phytolacca americana L. (Phytolaccaceae) may be toxic. Despite heated controversy over the toxic compounds of P. americana, especially esculentosides, relevant studies remain scarce. OBJECTIVE: The objective of this study is to screen the toxic fractions and compounds of P. americana, to determine the controlling indices, and to provide evidence for unraveling the mechanism. MATERIALS AND METHODS: Petroleum ether (PE), CH2Cl2, n-BuOH, and water fractions were isolated from 70% ethanol extract of P. americana. The n-BuOH fraction was dissolved in 50% ethanol and precipitated by adding ethyl ether. The resultant supernatants and precipitates were referred to as SUPs and SEDs fractions, respectively. SUPs fraction was separated by column chromatography into four main stimulating esculentosides that were identified by HR-ESI/MS and NMR as EsA, EsB, EsC, and EsF. The irritating effects of esculentosides on rabbit conjunctivae (500 µg/eye) was observed by pathological examination and those on macrophages (5, 25, 50 and 100 µg/mL) were evaluated by detecting changes of NO, TNF-α, and IL-1ß levels. RESULTS AND DISCUSSION: n-BuOH, SUP fractions, and EsC induced severe conjunctival edema. The four esculentosides induced dose-dependent releases of proinflammatory mediators NO, TNF-α, and IL-1ß from macrophages, and releasing amounts peaked after 2 h of treatment. EsC and EsF induced macrophages to release mediators most significantly. EsC (50 µg/mL) functioned more effectively than EsF did, and similarly n-BuOH and SUPs fractions functioned more effectively than the esculentoside mixture. Thus, the four esculentosides exerted proinflammatory effects synergistically. CONCLUSION: All extracted esculentosides, especially EsC, induced inflammatory stimulation. Phytolacca americana-induced irritation of the gastrointestinal tract may be associated with esculentosides such as EsC.

IL-13 Stimulates Proliferation and Expression of Mucin and Immunomodulatory Genes in Cultured Conjunctival Goblet Cells.

PURPOSE: To investigate the effects of IL-13 on goblet cell proliferation, differentiation, and expression of mucin and immunomodulatory genes. METHODS: Explants were excised from the conjunctiva of young C57BL/6 mice. Cultures received 200 µL per week of either Keratinocyte media (KSFM) or KSFM supplemented with 10 ng/mL IL-13 and were incubated for 3 (D3), 7 (D7), or 14 (D14) days. Subsequently, cell proliferation was assessed or cultures were immunostained, collected for dot blot, or for reverse transcription (RT) and quantitative real-time PCR (qPCR) or for RT-PCR gene array. RESULTS: The cultured conjunctival epithelium expressed goblet cell associated keratin 7 and mucins MUC5AC and MUC2 and when stimulated with IL-13 showed increased proliferation at D3 and D7 (P < 0.05) compared with control. MUC5AC expression was increased in the IL-13-treated group at D3 and D14 (P < 0.05). IL-13-treated cultures showed increased chemokine ligand 26 (CCL26), chloride channel calcium activated channel 3 (CLCA3), fas ligand (FasL), and Relm-ß at D7. All conjunctival cultures expressed MUC2, and its expression was decreased at D3 (P < 0.05) and increased at D14 (P < 0.05) with IL-13 treatment. CONCLUSIONS: This study demonstrated that conjunctival goblet cells are IL-13 responsive cells that produce factors known to maintain epithelial barrier, stimulate mucin production, and modulate immune response in nonocular mucosa when treated with IL-13. The functional significance of IL-13-stimulated factors remains to be determined.

Evaluation of oxidative stress levels in the conjunctival epithelium of patients with or without dry eye, and dry eye patients treated with preservative-free hyaluronic acid 0.15 % and vitamin B12 eye drops.

PURPOSE: Increased levels of oxidative stress have been seen in animal models of dry eye and in the conjunctival epithelial cells of patients with Sjögren's syndrome. The aims of this study were to compare the levels of oxidative stress in patients with dry eye and patients without dry eye and to evaluate the effects of treatment with preservative-free eye drops containing hyaluronic acid 0.15 % and vitamin B12 on oxidative stress and dry eye symptoms. METHODS: Three cohorts of patients who were to undergo planned cataract surgery were enrolled: patients with dry eye randomized to either no treatment (n = 29) or treatment (n = 32) with hyaluronic acid/vitamin B12 eye drops, and patients without dry eye (n = 42). Patients were assessed by Schirmer's type I test, fluorescein clearance test (FCT), Break Up Time (BUT), and Ocular Surface Disease Index (OSDI). Lipid peroxidation, a marker of oxidative stress, was assessed by LP-CHOLOX test. RESULTS: Compared with patients without dry eye, patients with dry eye had significantly increased levels of oxidative stress, higher OSDI and FCT scores, and significantly lower Schirmer's test and BUT scores. Treatment with eye drops containing hyaluronic acid 0.15 % and vitamin B12 was associated with significantly reduced levels of oxidative stress and OSDI and FCT scores and significantly increased Schirmer's test and BUT scores. CONCLUSIONS: These findings indicate that oxidative stress is associated with dry eye and that hyaluronic acid/vitamin B12 eye drops may attenuate oxidative stress and inflammation, improving dry eye symptoms. Further study in controlled clinical trials is warranted.

Inflammation and keratoconus.

Keratoconus (KC) has been traditionally classified as a noninflammatory disease. Barring loss of function, the other classic signs of inflammation (heat, redness, swelling, pain) are not usually obvious or even apparent in KC. This clinical perspective examines the evidence and implications of numerous inflammatory processes that have been recognized in the tears of KC patients as well as some inflammation relevant differences found in the KC cornea. The roles of inflammation in corneal trauma attributed to eye rubbing and/or contact lens wear are examined as is the significance of atopy, allergic disease, dry eye disease, degradative enzyme activity, wound healing, reduced anti-inflammatory capacity, and ultraviolet irradiation. It is possible that any comorbidity that is inflammatory in nature may add synergistically to other forms of KC-related inflammation and exacerbate its pathogenetic processes. For example, some features of inflammation in ocular rosacea and associated corneal thinning and distortion could have some possible relevance to KC. An analogy is drawn with osteoarthritis, which also involves significant inflammatory processes but, like KC, does not meet all the classic criteria for an inflammatory disease. Classifying KC as quasi-inflammatory (inflammatory-related) rather than a noninflammatory disease appears to be more appropriate and may help focus attention on the possibility of developing effective anti-inflammatory therapies for its management.

Effects of eye drops containing a mixture of omega-3 essential fatty acids and hyaluronic acid on the ocular surface in desiccating stress-induced murine dry eye.

PURPOSE: To investigate the efficacy of the topical application of omega-3 essential fatty acids (EFAs) and hyaluronic acid (HA) mixtures in a mouse model of experimental dry eye (EDE). METHODS: Eye drops consisting of 0.1% HA, 0.02%, or 0.2% omega-3 EFAs alone and mixture of 0.02%, or 0.2% omega-3 EFAs and 0.1% HA were applied in desiccating stress-induced murine dry eye. Corneal irregularity scores and fluorescein staining scores were measured 5 and 10 days after treatment. Levels of interleukin (IL)-1ß, -17, and interferon gamma-induced protein (IP)-10 were measured in the conjunctiva at 10 days using a multiplex immunobead assay. The concentrations of hexanoyl-lys (HEL) and 4-hydroxynonenal (4-HNE) in conjunctiva tissue were measured with enzyme-linked immunosorbent assays. RESULTS: Mice treated with the mixture containing 0.2% omega-3 EFAs showed a significant improvement in corneal irregularity scores and corneal fluorescein staining scores compared with EDE, HA, 0.02% or 0.2% omega-3 EFAs alone, and 0.02% omega-3 EFAs mixture-treated mice. A significant decrease in the levels of IL-1ß, -17, and IP-10 were observed in the 0.2% EFAs mixture-treated group, compared with the other groups. In the mice treated with the mixture containing 0.2% omega-3 EFAs, the concentration of 4-HNE was also lower than the other groups. Although 0.2% omega-3 EFAs alone group also had a significant improvement in corneal irregularity scores and IL-17, IL-10, and 4 HNE levels compared with the other groups, the efficacy was lower than 0.2% omega-3 mixture group. CONCLUSIONS: Topically applied eye drops containing a mixture of omega-3 EFAs and HA could improve corneal irregularity and corneal epithelial barrier disruption, and decrease inflammatory cytokines and oxidative stress markers on the ocular surface. Topical omega-3 EFAs and HA mixture may have a greater therapeutic effect on clinical signs and inflammation of dry eye compared with HA artificial tears.

Alpha-lipoic acid restores tear production in an animal model of dry eye.

The tear film comprises a major mechanism for protection of the ocular surface against harmful external agents. Disruption of tear production can lead to dry eye syndrome, causing damage ranging from mild discomfort to scarring of the ocular surface with irreversible vision impairment. The production of tears by the lacrimal gland is influenced by neuroendocrine, hormonal, and immunological factors. Reactive oxygen and nitrogen species play an important role in its regulation. We assessed the effects of oxidative stress on antioxidant defenses in the lacrimal gland and ocular surface in ovariectomized rats supplemented with n-3 polyunsaturated fatty acids (n-3 PUFA) and alpha-lipoic acid (ALP). We found that n-3 PUFA did not measurably influence oxidative stress, but ALP had site-specific pro-oxidant and antioxidant effects, and was an important influence on ocular surface dry eye improvement. As an index of oxidative damage to proteins and lipids, we measured levels of carbonyl and malondialdehyde (MDA), respectively. Enzymatic antioxidant defenses were measured as total superoxide dismutase (tSOD) and glutathione peroxidase (GPx), and non-enzymatic defenses were estimated by vitamin C, total glutathione, and indirect oxide nitric levels. PUFA and ALP treatment restored lacrimal production with resulting improvement in the dry eye Schirmer test in all supplemented groups. The results indicated that reactive oxygen species resulting from oxidative stress in the lacrimal gland did not play an important role in dry eye through reactive oxygen species; however, alpha-lipoic acid altered the metabolism of reactive nitrogen species, causing increased activity of lacrimal peroxidase and improved lacrimal production.

Dietary α-lipoic acid prevents UVB-induced corneal and conjunctival degeneration through multiple effects.

PURPOSE: This study investigated the effects of dietary α-lipoic acid (α-LA) against ultraviolet B (UVB)-induced corneal and conjunctival degeneration in a mouse model. METHODS: Female CBA mice were randomly divided into five study groups, including blank control, UVB without α-LA, and UVB with dietary α-LA at 1, 10, and 100 mg/kg body weight. Following UVB exposure, corneal surfaces were assessed along with immunohistochemistry for nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2), malondialdehyde (MDA) accumulation, and P63⁺ basal cell distribution. Matrix metalloproteinase (MMP)-2 and MMP-9 activities were determined by gelatin zymography. ELISA assay was performed to confirm the findings of immunohistochemistry for NF-κB, COX-2, and MDA, along with the levels of TNF-α and IL-6. Tear production and goblet cell density were determined after tear strip assay and periodic acid Schiff staining, respectively. RESULTS: The results showed that UVB irradiation caused corneal surface damage, polymorphonuclear leukocyte infiltration, and loss of P63⁺ basal cells. Dietary α-LA ameliorated the UVB-induced corneal damage while simultaneously reducing MDA accumulation and maintaining P63⁺ basal cell survival. NF-κB-p65, COX-2, TNF-α, IL-6, and MMP-9 activity were all reduced by dietary α-LA. In addition, α-LA helped to reverse aqueous tear reduction, conjunctival squamous epithelium metaplasia, and goblet cell loss after UVB exposure. CONCLUSIONS: Dietary α-LA can prevent UVB-induced corneal damage and can be used as a prophylactic agent prior to excessive UVB exposure.

Osmoprotective effects of supplemental epidermal growth factor in an ex vivo multilayered human conjunctival model under hyperosmotic stress.

BACKGROUND: To analyze the effects of supplemental epidermal growth factor (EGF) and the roles of inflammatory cytokines (interleukin [IL]-6) in an ex vivo dry-eye model under hyperosmotic stress using a multilayered culture of human conjunctival epithelial cells (HCECs). METHODS: Multilayered cultures of HCECs were exposed to hyperosmotic stress (400 mOsm/L) for 24 h in addition to 0.5 ng/mL EGF (low-EGF group) or 25 ng/mL EGF (high-EGF group). Apoptosis was analyzed using the TUNEL assay. Cell proliferation was measured using the [3H]-thymidine incorporation assay. The expression of IL-6, EGF, EGF receptor (EGFR), and phosphorylated extracellular signal-regulated kinase (p-ERK) was measured by western blot analysis. The secretion of IL-6 was measured using ELISA. Western blot analysis was also performed using antibodies against cleaved caspase-3. RESULTS: The percentage of apoptotic cells was lower in the high-EGF group (6.7%) than in the low-EGF group (10.3%). The high-EGF group demonstrated increased proliferation (323.7 counts/min in the low-EGF group vs 649.1 counts/min in the high-EGF group). EGF induced higher phosphor-EGFR expression and upregulated p-ERK in HCECs. In addition, EGF significantly decreased the secretion of IL-6 and cleaved caspase-3 in HCECs. CONCLUSIONS: The level of IL-6 was increased in the ex vivo HCEC dry-eye model that was under hyperosmotic stress. Supplemental EGF reduces the level of IL-6, decreases apoptosis, and increases proliferation. These findings indicate that EGF has potential as a therapeutic agent for the treatment of dry eyes.