Dry Eye Mouse Research Articles

Macrophage Phenotype in the Ocular Surface of Experimental Murine Dry Eye Disease.

To evaluate the phenotype of macrophages in the cornea and conjunctiva of C57BL/6 mice with induced experimental dry eye. C57BL/6 mice exposed to desiccating stress (DS) were evaluated at 1, 5, and 10 days and C57BL/6 mice maintained in non-stressed environment were used as controls. Whole eyes and adnexa were excised for histology or used for gene expression analysis. Location and phenotype of macrophages infiltrating the cornea and conjunctiva was evaluated by immunofluorescence analysis. Quantitative polymerase chain reaction evaluated macrophage markers and T cell-related and inflammatory cytokine expression in cornea and conjunctiva. Immunofluorescence staining demonstrated that macrophages reside in the conjunctiva of control and dry eye mice and their number did not change with DS. Real-time RT-PCR demonstrated that the level of M1 macrophage marker, iNOS, increased prominently in the conjunctiva at DS 10 days. In contrast, there was a non-significant decrease of the M2 marker Arg1 with DS. The levels of inflammatory cytokine, IL-12a mRNA transcript in the conjunctiva increased significantly at DS1 and decreased at DS5, while levels of IL-18 were significantly increased at DS 10. Macrophages reside in the ocular surface tissues of C57BL/6 mice. Although the number of macrophages in the conjunctiva does not change, evidence of inflammatory M1 activation after desiccating stress was observed. Better understanding of phagocyte diversity and activation in dry eye disease provide a basis for the development of phagocyte-targeted therapeutic strategies.

Effect of 0.025% FK-506 eyedrops on botulinum toxin B-induced mouse dry eye.

To investigate the effect of FK-506 eye drops on Botulinum toxin B (BTX-B)-induced mouse dry eye. Forty-five CBA/J mice were followed up for 4 weeks after treatment with 0.025% FK-506, vehicle or 0.9% saline eye drops 3 days after intralacrimal glands injection with 20 milliunits BTX-B. Tear production, corneal fluorescein staining, the mRNA, and protein expression of cytokines were measured. The activation of nuclear factor-κB (NF-κB) was detected by Western blotting. The infiltration of inflammatory cells was examined by immunohistochemistry. After treated with FK-506 eye drops, aqueous tear production in the mice began to recover at week 1, and then increased to the levels of pre-BTX-B injection at week 4 (2.21 ± 0.43 vs. 2.52 ± 0.71 mm, t = 0.84, P > 0.05). The severity of corneal epithelial defects was alleviated at week 2 and further improved at week 4 when compared with those in the vehicle- and saline-treated groups. The gene expression of IL-1β and TNF-α in the FK-506 and vehicle-treated groups were 47.01% and 45.56%, 85.91% and 115.83% of that in the saline-treated group in the ocular surface, while in the lacrimal glands 49.16% and 67.60%, 94.91% and 95.77% of that in the saline-treated group, respectively. The ratio of phosphorylated IκB-α to total IκB-α in the keratoconjunctival tissues was lower in the FK-506-treated group than in the vehicle- and saline-treated groups (both P < 0.05). No inflammatory cells were detected in all groups. Topical application of FK-506 can inhibit NF-κB activation and related inflammatory response and alleviate the signs of dry eye.

Serine protease inhibitor A3K suppressed the formation of ocular surface squamous metaplasia in a mouse model of experimental dry eye.

To investigate the effects and possible mechanisms of serine protease inhibitor A3K (SERPINA3K) on the formation of ocular surface squamous metaplasia in a mouse dry eye model induced by topical benzalkonium chloride (BAC). The eye drops containing SERPINA3K were topically administered during the induction of BAC-induced dry eye. The clinical indications of dry eye were evaluated on day (D)16, including tear break-up time (BUT), tear volume, corneal fluorescein staining, and inflammatory index. Global specimens were collected on D16 and the following examinations were performed: histologic investigation, immunostaining of cytokeratin 10 (K10), p63 and Ki67 in the cornea, and Western blot analysis of tumor necrosis factor-α (TNF-α). Serine protease inhibitor A3K suppressed the formation of BAC-induced dry eye, presenting with longer BUTs, lower corneal fluorescein staining scores, and inflammatory index, while no significant changes in tear volume. It also reduced the severity of abnormal differentiation and proliferation on ocular surface with lower expressions of K10, p63, and Ki67, and retained the number of goblet cells in the conjunctival fornix. Serine protease inhibitor A3K significantly decreased the levels of TNF-α in the cornea. Topical application of SERPINA3K ameliorated the severity of ocular surface squamous metaplasia and suppressed the formation of BAC-induced dry eye.

Does estrogen deficiency cause lacrimal gland inflammation and aqueous-deficient dry eye in mice?

Researchers have proposed that estrogen deficiency will lead to a Sjögren's syndrome (SjS)-like lacrimal gland inflammation, aqueous tear deficiency and dry eye. The purpose of this study was to determine whether this proposal is correct. Lacrimal glands were obtained from adult, age-matched wild type (WT) and aromatase knockout (ArKO) mice, in which estrogen synthesis is completely eliminated. Tissues were also obtained from autoimmune MRL/Mp-lpr/lpr (MRL/lpr) mice as inflammation controls. Tear volumes in WT and ArKO mice were measured and glands were processed for molecular biological and histological evaluation. Our results demonstrate that estrogen absence does not lead to a SjS-like inflammation in lacrimal tissue or to an aqueous-deficient dry eye. There was no upregulation of genes associated with inflammatory pathways in lacrimal glands of male or female ArKO mice. Such inflammatory activity was prominent in autoimmune MRL/lpr tissues. We also found no evidence of inflammation in lacrimal gland tissue sections of estrogen-deficient mice, and tear volumes of ArKO males were actually increased as compared to those WT controls. Interestingly, our study did show that estrogen absence influences the expression of thousands of lacrimal gland genes, and that this impact is sex- and genotype-specific. Our findings demonstrate that estrogen absence is not a risk factor for the development of SjS-like lacrimal gland inflammation or for aqueous-deficient dry eye in mice.

Mice lacking inositol 1,4,5-trisphosphate receptors exhibit dry eye.

Tear secretion is important as it supplies water to the ocular surface and keeps eyes moist. Both the parasympathetic and sympathetic pathways contribute to tear secretion. Although intracellular Ca2+ elevation in the acinar cells of lacrimal glands is a crucial event for tear secretion in both the pathways, the Ca2+ channel, which is responsible for the Ca2+ elevation in the sympathetic pathway, has not been sufficiently analyzed. In this study, we examined tear secretion in mice lacking the inositol 1,4,5-trisphosphate receptor (IP3R) types 2 and 3 (Itpr2−/−;Itpr3−/−double-knockout mice). We found that tear secretion in both the parasympathetic and sympathetic pathways was abolished in Itpr2−/−;Itpr3−/− mice. Intracellular Ca2+ elevation in lacrimal acinar cells after acetylcholine and epinephrine stimulation was abolished in Itpr2−/−;Itpr3−/− mice. Consequently, Itpr2−/−;Itpr3−/− mice exhibited keratoconjunctival alteration and corneal epithelial barrier disruption. Inflammatory cell infiltration into the lacrimal glands and elevation of serum autoantibodies, a representative marker for Sjögren’s syndrome (SS) in humans, were also detected in older Itpr2−/−;Itpr3−/− mice. These results suggested that IP3Rs are essential for tear secretion in both parasympathetic and sympathetic pathways and that Itpr2−/−;Itpr3−/− mice could be a new dry eye mouse model with symptoms that mimic those of SS.

Therapeutic effects of topical doxycycline in a benzalkonium chloride-induced mouse dry eye model.

We investigated the therapeutic effects and underlying mechanisms of topical doxycycline in a benzalkonium chloride (BAC)-induced mouse dry eye model. Eye drops containing 0.025%, 0.1% doxycycline or solvent were administered to a BAC-induced dry eye model four times daily. The clinical evaluations, including tear break-up time (BUT), fluorescein staining, inflammatory index, and tear volume, were performed on days 0, 1, 4, 7, and 10. Global specimens were collected on day 10 and processed for immunofluorescent staining, TUNEL, and periodic acid-Schiff assay. The levels of inflammatory mediators in the corneas were determined by real-time PCR. The total and phosphorylated nuclear factor-κB (NF-κB) were detected by Western blot. Both 0.025% and 0.1% doxycycline treatments resulted in increased BUT, lower fluorescein staining scores, and inflammatory index on days 4, 7, and 10, while no significant change in tear volume was observed. The 0.1% doxycycline-treated group showed more improvements in decreasing fluorescein staining scores, increasing Ki-67-positive cells, and decreasing TUNEL- and keratin-10-positive cells than other groups. The mucin-filled goblet cells in conjunctivas were increased, and the expression of CD11b and levels of matrix metalloproteinase-9, IL-1β, IL-6, TNF-α, macrophage inflammatory protein-2, and cytokine-induced neutrophil chemoattractant in corneas were decreased in both doxycycline-treated groups. In addition, doxycycline significantly reduced the phosphorylation of NF-κB activated in the BAC-treated corneas. Topical doxycycline showed clinical improvements and alleviated ocular surface inflammation on BAC-induced mouse dry eye, suggesting a potential as an anti-inflammatory agent in the clinical treatment of dry eye.

Decreased PPAR-γ expression in the conjunctiva and increased expression of TNF-α and IL-1β in the conjunctiva and tear fluid of dry eye mice

The aim of this study was to investigate the expression of peroxisome proliferator-activated receptorγ (PPAR-γ), tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the conjunctiva and the association between inflammatory cytokines and PPAR-γ in dry eye mice. Dry eye was induced in 6-week-old female C57 mice. mRNA expression of PPAR-γ, TNF-α and IL-1β were measured. PPAR-γ protein expression in the conjunctiva, and the contents of TNF-α and IL-1β in the conjunctiva and tear-wash fluid were determined. A PPAR-γ agonist, pioglitazone (PIO), was used to treat dry eye mice. Dry eye mice presented with similar manifestations as in humans. The PPAR-γ expression in the conjunctiva of dry eye mice was downregulated, accompanied by increased contents of TNF-α and IL-1β. PIO treatment markedly reduced the contents of TNF-α and IL-1β in tear fluid of dry eye mice. Following PIO treatment, the PPAR-γ expression increased markedly. PIO may activate PPAR-γ to inhibit the expression of the inflammatory cytokines TNF-α and IL-1β in dry eye mice. This suppresses the inflammatory progression, increases the tear fluid production, elevates the tear film stability and reduces the damage to the ocular surface, exerting a therapeutic effect on dry eye.

Potential for daily supplementation of n-3 fatty acids to reverse symptoms of dry eye in mice

The purpose of this study was to determine the change in tear volume, as a predominant symptom of dry eye syndrome, in dietary n-3 fatty acid deficient mice compared with n-3 fatty acid adequate mice. The tear volume in n-3 fatty acid deficient mice was significantly lower than that in n-3 fatty acid adequate mice. In addition, the concentration of n-3 fatty acid in the lacrimal and meibomian glands, which affects the production of tears, was markedly decreased compared with n-3 fatty acid adequate mice. However, the tear volume recovered almost completely after one week of continuous administration of fish oil containing EPA and DHA in n-3 fatty acid deficient mice. Also, the concentration of DHA in the meibomian gland of n-3 fatty acid deficient group recovered to approximately 80% more than that of n-3 fatty acid adequate group. These results suggested that dietary n-3 fatty acids deficiency showed reversible dry eye syndrome, and that n-3 fatty acids have an important role in the production of tears.

Efficacy of Osmoprotectants on Prevention and Treatment of Murine Dry Eye

To evaluate the efficacy of osmoprotectants on prevention and treatment of dry eye in a murine model. Dry eye was induced in mice by using an intelligently controlled environmental system (ICES). Osmoprotectants betaine, L-carnitine, erythritol, or vehicle (PBS) were topically administered to eyes four times daily following two schedules: schedule 1 (modeling prevention): dosing started at the beginning of housing in ICES and lasted for 21 or 35 days; schedule 2 (modeling treatment): dosing started after ICES-housed mice developed dry eye (day 21), continuing until day 35. Treatment efficacy was evaluated for corneal fluorescein staining; corneal epithelial apoptosis by TUNEL and caspase-3 assays; goblet cell numbers by PAS staining; and expression of inflammatory mediators, TNF-α, IL-17, IL-6, or IL-1β by using RT-PCR on days 0, 14, 21, and/or 35. Compared with vehicle, prophylactic administration of betaine, L-carnitine, or erythritol significantly decreased corneal staining and expression of TNF-α and IL-17 on day 21 (schedule 1). Treatment of mouse dry eye with osmoprotectants significantly reduced corneal staining on day 35 compared with day 21 (schedule 2). Relative to vehicle, L-carnitine treatment of mouse dry eye for 14 days (days 21 to 35) resulted in a significant reduction in corneal staining, number of TUNEL-positive cells, and expression of TNF-α, IL-17, IL-6, or IL-1β, as well as significantly increased the number of goblet cells. Topical application of betaine, L-carnitine, or erythritol systematically limited progression of environmentally induced dry eye. L-carnitine can also reduce the severity of such dry-eye conditions.

Amniotic membrane extract ameliorates benzalkonium chloride-induced dry eye in a murine model

Human amniotic membrane (AM) is avascular but contains various beneficial bioactive factors, its extract (AE) is also effective in treating many ocular surface disorders. In this study, we for the first time evaluated the therapeutic effects of AE on dry eye induced by benzalkonium chloride in a BALB/c mouse model. Topical application of AE (1.5 and 3 μg/eye/day) resulted in significantly longer tear break-up time on Day 3 and 6, lower fluorescein staining scores on Day 3, and lower inflammatory index on Day 6. AE reduced corneal epithelial K10 expression, inflammatory infiltration, and levels of TNF-α, IL-1β and IL-6 in BAC treated mice than that in the control mice. Moreover, decreased TUNEL positive cells in cornea and increased goblet cells in conjunctiva were also observed in AE treated corneas. Finally, AE induced more Ki-67 positive cells in corneal epithelium of dry eye mouse. Taken together, our data provide further support for BAC induced dry eye model as a valuable for dry eye study and suggest a great potential for AE as a therapeutic agent in the clinical treatment of dry eye.

Transduced PEP-1-FK506BP ameliorates corneal injury in Botulinum toxin A-induced dry eye mouse model

FK506 binding protein 12 (FK506BP) belongs to a family of immunophilins, and is involved in multiple biological processes. However, the function of FK506BP in corneal disease remains unclear. In this study, we examined the protective effects on dry eye disease in a Botulinum toxin A (BTX-A) induced mouse model, using a cell-permeable PEP-1-FK506BP protein. PEP-1-FK506BP efficiently transduced into human corneal epithelial cells in a time- and dose-dependent manner, and remained stable in the cells for 48 h. In addition, we demonstrated that topical application of PEP-1-FK506BP was transduced into mouse cornea and conjunctiva by immunohistochemistry. Furthermore, topical application of PEP-1-FK506BP to BTX-A-induced mouse model markedly inhibited expression levels of pro-inflammatory cytokines such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and macrophage inhibitory factor (MIF) in corneal and conjunctival epithelium. These results suggest PEP-1-FK506BP as a potential therapeutic agent for dry eye diseases. [BMB Reports 2013; 46(2): 124-129]

Intraglandular Injection of Botulinum Toxin A Reduces Tear Production in Rabbits

To develop an animal model and investigate the dose-dependent effect of an intraglandular injection of botulinum toxin A (BTX-A) on tear production. In a volume of 0.1-ml, 0.625-, 1.25-, or 2.5-U BTX-A was injected transconjunctivally in the superolateral lobe of the lacrimal gland of adult New Zealand white female rabbits. In the contralateral lacrimal gland, 0.1 ml of 0.9% sodium chloride was injected. Prior to injection and at 1-week postinjection, photographs were taken to evaluate pre- and postoperative eyelid position. Fluorescein and Rose Bengal stain were used to evaluate the corneal surface, and Schirmer test was used to assess tear production. Glands injected with the intermediate (1.25 U) and the highest (2.5 U) doses of BTX-A displayed a statistically significant decrease in tear production (p = 0.002 and 0.007, respectively) compared with the contralateral saline-injected glands at 1 week. No corneal pathologic factors from excessive dryness were observed following the injection. While postinjection ptosis was observed (p = 0.025), no difference was seen between BTX-A and saline-injected eyes. In rabbits, intraglandular injection of BTX-A resulted in decreased tear production at 1 week. No additional reduction in tear production was seen with a BTX-A dose greater than 1.25 U, suggesting glandular receptor saturation at this dose. Despite suppression of tear production, no corneal pathologic factors were observed. Further studies are needed to refine this animal model with the ultimate goal of determining optimum delivery route and concentration to reduction in tear production while minimizing side effects in patients.

A nanomedicine to treat ocular surface inflammation: performance on an experimental dry eye murine model

MUC5AC is a glycoprotein with gel-forming properties, whose altered expression has been implicated in the pathogenesis of dry eye disease. The aim of our study was to achieve an efficient in vivo transfection of MUC5AC, restore its normal levels in an inflamed ocular surface and determine whether restored MUC5AC levels improve ocular surface inflammation. Cationized gelatin-based nanoparticles (NPs) loaded with a plasmid coding a modified MUC5AC protein (pMUC5AC) were instilled in healthy and experimental dry eye (EDE) mice. MUC5AC expression, clinical signs, corneal fluorescein staining and tear production were evaluated. Ocular specimens were processed for histopathologic evaluation, including goblet cell count and CD4 immunostaining. Neither ocular discomfort nor irritation was observed in vivo after NP treatment. Expression of modified MUC5AC was significantly higher in ocular surface tissue of pMUC5AC-NP-treated animals than that of controls. In healthy mice, pMUC5AC-NPs had no effect on fluorescein staining or tear production. In EDE mice, both parameters significantly improved after pMUC5AC-NP treatment. Anterior eye segment of treated mice showed normal architecture and morphology with lack of remarkable inflammatory changes, and a decrease in CD4+ T-cell infiltration. Thus, pMUC5AC-NPs were well tolerated and able to induce the expression of modified MUC5A in ocular surface tissue, leading to reduction of the inflammation and, consequently improving the associated clinical parameters, such as tear production and fluorescein staining. These results identify a potential application of pMUC5AC-NPs as a new therapeutic modality for the treatment of dry eye disease.

Autoantibodies Contribute to the Immunopathogenesis of Experimental Dry Eye Disease

The purpose of this study was to determine if autoantibodies play a role in the immunopathogenesis of experimental dry eye disease. Dry eye was induced by exposing female C57BL/6 wild-type mice or hen egg lysozyme B-cell receptor transgenic mice to desiccating stress (subcutaneous scopolamine [0.5 mg/0.2 mL] 3 times a day, humidity < 40%, and sustained airflow) for 3 weeks, allowing sufficient time for a humoral immune response. Serum or purified IgG isolated from dry-eye mice or untreated controls was passively transferred to nude recipient mice, which were evaluated for ocular surface inflammation 3 days after transfer. To determine if complement activation contributed to serum-induced dry eye disease, cobra venom factor was used to deplete complement activity. Autoantibodies against kallikrein 13 were identified in serum from dry-eye mice, but were undetectable in untreated controls. Autoantibody-containing serum or purified IgG from dry-eye mice was sufficient to mediate complement-dependent ocular surface inflammation. Serum or purified IgG caused marked inflammatory burden and tissue damage within the ocular surface tissues, including elevated Gr1+ neutrophil infiltration and proinflammatory cytokines/chemokines associated with goblet cell loss. Moreover, complement C3b deposition was found within the ocular surface tissues of mice receiving dry-eye serum, but not in recipients of control serum. Functionally, complement depletion attenuated the ability to transfer dry-eye-specific serum or IgG-mediated disease. These data demonstrate for the first time a complement-dependent pathogenic role of dry-eye-specific autoantibodies, and suggest autoantibody deposition within the ocular surface tissues contributes to the predominantly T-cell-mediated immunopathogenesis of dry eye disease.

A primary study of L-carnitine protective effect on corneal and conjunctival epithelium of mouse dry eye model induced by hyperosmolar saline

To evaluate protective effects of L-carnitine on corneal and conjunctival epithelium of mouse dry eye model induced by hyperosmolar saline. Sixty female BALB/c mice at the age of 6 - 8 weeks were randomly divided into three groups (20 in each): Hyperosmolar saline group (HO), Hyperosmolar and Isosmotic saline group (HO + IO), as well as Hyperosmolar saline and 1% L-carnitine group (HO + 1%LCA). The HO group was treated with 500 mOsmol/L sodium chloride solution; the HO + IO group with 308 mOsmol/L sodium chloride solution first and 500 mOsmol/L sodium chloride solution 30 minutes later; and the HO + 1%LCA group with 1%L-carnitine eye drop first and 500 mOsmol/L sodium chloride solution 30 minutes later. Alternately, 5 times a day for 28 days. Corneal fluorescein staining, corneal epithelial hematoxylin-eosin staining and thickness measurement, conjunctival epithelial periodic acid-schiff reagent staining and goblet cell counting were conducted on 0, 7th, 14th and 28th days, respectively. On 28th day, corneal surface was inspected by scaning electron microscopy and tear osmolarity was measured. In HO or HO + IO group, compared with HO + 1%LCA group, the number of goblet cells was reduced, the score of corneal fluorescein staining and corneal epithelial thickness was elevated: on 7th day, there was difference noticed in the corneal epithelial thickness [(27.7 ± 1.1), (26.5 ± 1.4), (25.1 ± 1.0) µm, P < 0.01] and the number of goblet cell [(11.9 ± 1.1), (12.1 ± 0.9), (13.3 ± 0.9), P < 0.01] in 3 groups; on 14th day, there was evident change in the corneal fluorescein staining area [(3.2 ± 0.9), (2.9 ± 0.7), (1.7 ± 0.8), χ(2) = 11.465, P < 0.01] in 3 groups. On 28th day, Increased tear osmolarity and lowered microvilli on cornea were examined in HO [(327.37 ± 4.20) mOsmol/L] or HO + IO [(324.36 ± 5.72) mOsmol/L] group compared with HO + 1%LCA [(308.29 ± 5.72) mOsmol/L] group (P < 0.01). L-carnitine had protective effect on corneal and conjunctival epithelium of mouse dry eye model induced by hyperosmolar saline, and should be studied further.

Effect of Topically Applied Epithelial Sodium Channel Inhibitors on Tear Production in Normal Mice and in Mice with Induced Aqueous Tear Deficiency

Dry eye syndromes affect a significant proportion of the population worldwide with reported prevalence ranging from 6% to more than 34%. Patients with dry eye can experience intense pain due to eye irritation, gritty/scratchy feeling in the eyes, blurry vision, and light sensitivity. Available treatments for dry eye syndromes remain mainly palliative. The purpose of the present study was to test the hypothesis that inhibiting sodium absorption via the epithelial sodium channel (ENaC) will increase ocular hydration in both normal as well as in animals with experimentally induced dry eye. ENaC inhibitors were dissolved in an aqueous buffer that mimics the composition of tears and were applied topically to the ocular surface of isoflurane-anesthetized mice. The effect of ENaC inhibitors was compared with that of the secretagogue uridine triphosphate (UTP; 1%), a purinergic receptor agonist which was shown to increase tear volume in animals. Tear production was measured for 10 s using phenol red-impregnated cotton threads. Fluorescein staining that assesses ocular surface damage was performed at baseline and then at days 1, 2, and 3 after the induction of dry eye in mice. Our data show that the inhibition of ENaC led to a time- and concentration-dependent increase in tear volume in normal mice. The effect of ENaC inhibition after a single application outperformed UTP, as it was long-lasting with tear volume still above baseline values 8 h postdosing. ENaC inhibition, which led to increased tear production, improved fluorescein scores in our dry eye model, when compared with nontreated or animals treated with buffer or UTP. We conclude that the inhibition of ENaC provides long-lasting increases in ocular surface hydration and that ENaC blockers could provide an effective new therapy for chronic dry eye.

Therapeutic Effects of Epidermal Growth Factor on Benzalkonium Chloride–Induced Dry Eye in a Mouse Model

To investigate the therapeutic effects and possible mechanisms of epidermal growth factor (EGF) on the mouse dry eye model induced by benzalkonium chloride (BAC). The eye drop containing EGF was topically administered (3 ng per day) on a BAC-induced dry eye model. The following clinical indications of dry eye were evaluated on Days 2, 4, and 6: tear break-up time (BUT), corneal fluorescein staining, inflammatory index, and tear volume. Global specimens were collected on Day 6 and then the following examinations were performed: histologic investigation, TUNEL assay to measure the dead cells, periodic acid-schiff (PAS) assay to detect goblet cells, and immunostaining of antibodies of Ki-67, EGF receptor (EGFR), and MUC1 in the corneas. The levels of EGFR and p-ERK of the corneas were also measured by Western blot analysis. EGF resulted in longer BUTs on Days 2 and 6, lower fluorescein staining scores on Days 4 and 6, while no significant changes in inflammatory index or tear volume. EGF induced higher EGFR expression in corneal tissues by immunofluorescent staining and Western blot analysis. EGF also upregulated p-ERK, increased Ki-67 positive cells, and decreased TUNEL positive cells. In addition, EGF significantly increased the goblet cells number and MUC1 expression in the epithelium. Topical application of EGF presented clinical improvements on dry eye by stabilizing the tear film and maintaining the integrity of epithelium. The results indicate that EGF has potential as a therapeutic agent in clinical treatment of dry eye.

Therapeutic effects of Pyranoprofen on the mouse dry eye induced by topical medication of Benzalkonium Chloride

Randomized controlled experimental study to investigate the therapeutic effect and the possible mechanism of Pranoprofen on the recovery of dry eye induced by topical medication of Benzalkonium Chloride (BAC) in mouse. It was an experimental study. Seventy BALB/c mice were treated with topical administration of 0.25% BAC to establish the dry eye condition. Based on the consistency of break-up time of tear-film (BUT), corneal fluorescein staining scores and inflammation index, the eyes were re-selected and randomly divided into four groups on day (D) 21 after the BAC treatment. Group A was set up as blank control, while group B, C and D were treated respectively with 0.1% sodium hyaluronate eye drops, 0.1% fluorometholone eye drops plus 0.1% sodium hyaluronate eye drops, 0.1% pyranoprofen eye drops plus 0.1% sodium hyaluronate eye drops. BUTs, tear volumes, corneal fluorescein staining scores and inflammation index were evaluated in each group on D0, 1, 3 and 5 after the therapeutic treatment. Global specimens were collected on D6. Sections were stained with hematoxylin and eosin (HE) or by periodic acid-schiff (PAS) assay, and labeled with cytokeratin 10 (K10) antibody. The expression of tumor necrosis factor-α (TNF-α) in the cornea and conjunctiva was quantified by western blot. 72 eyes were included in the sequential experiment, 18 eyes for each group. On D0, 1 and 3, no clinical differences were observed among the groups. On D5, the BUT was (2.933 ± 0.320), (2.900 ± 0.280), (3.464 ± 0.498) and (3.643 ± 0.413) s in group A, B, C and D respectively; the BUTs in group C and D were significant longer than those of group A and B (F = 13.774, P = 0.000). The corneal fluorescein staining score was (11.640 ± 1.008), (11.790 ± 1.188), (10.330 ± 1.371) and (10.270 ± 1.104)s in group A, B, C and D respectively; the scores in group C and D were significant lower than those of group A and B (F = 6.145, P = 0.001). The corneal inflammatory index was (0.232 ± 0.059), (0.229 ± 0.078), (0.151 ± 0.055) and (0.154 ± 0.056) in group A, B, C and D respectively; the index in group C and D were significant lower than those of group A and B (F = 6.703, P = 0.001). No significant difference was found in tear volume among groups. No significant difference was found between Pyranoprofen and Fluorometholone treatment in BUT, corneal fluorescein score or inflammatory index. Corneal morphology showed the feature of thicker corneal epithelial layer in group A and uniformity in group C and D. PAS assay revealed similar goblet cell numbers in group C and D, but less goblet cells in group A and B. Cytokeratin 10 was almost negatively expressed in Pranoprofen or Fluorometholone treated groups, and remained positive in the corneal epithelium with other treatments. The level of TNF-α in the cornea was down-regulated in Pranoprofen or Fluorometholone treated groups. Pranoprofen or Fluorometholone combined with sodium hyaluronate treatment presented similar therapeutic effects on BAC-induced mouse dry eye, with the more stable tear film, the better regularity of epithelium recovery, the down-regulation of inflammatory TNF-α, the increased number of goblet cells, and the elimination of squamous metaplasia, when compared with the treatment of sodium hyaluronate eye drops only. Our results showed the great potentialities of Pranoprofen in the clinical treatment of ocular surface inflammation in the mild and severity dry eye.

SPLA2-IIa Amplifies Ocular Surface Inflammation in the Experimental Dry Eye (DE) BALB/c Mouse Model

sPLA2-IIa is a biomarker for many inflammatory diseases in humans and is found at high levels in human tears. However, its role in ocular surface inflammation remains unclear. An experimentally induced BALB/c mouse dry eye (DE) model was used to elucidate the role of sPLA2-IIa in ocular surface inflammation. BALB/c mice were subcutaneously injected with scopolamine and placed in a daytime air-drying device for 5 to 10 days. Control mice received no treatment. DE status was evaluated with tear production with a phenol-red thread method. Tear inflammatory cytokines were quantified by multiplex immunoassays. Ocular surface inflammation and sPLA2-IIa expression were examined by immune-staining and quantitative (q)RT(2)-PCR. Conjunctiva (CNJ) of the mice was cultured for prostaglandin E2 production induced by sPLA2-IIa with various amount of sPLA2-IIa inhibitor, S-3319. Treated mice produced fewer tears and heavier corneal (CN) fluorescein staining than the untreated controls (P < 0.001). They also revealed lower goblet cell density (P < 0.001) with greater inflammatory cell infiltration within the conjunctiva, and higher concentration of tear inflammatory cytokines than the controls. Moreover, treated mice showed heavier sPLA2-IIa immune staining than the controls in the CNJ epithelium, but not in the CN epithelium or the lacrimal gland. Treated mice exhibited upregulated sPLA2-IIa and cytokine gene transcription. Furthermore, CNJ cultures treated with sPLA2-IIa inhibitor showed significantly reduced sPLA2-IIa-induced inflammation. This is the first report regarding sPLA2-IIa in the regulation of ocular surface inflammation. The findings may therefore lead to new therapeutic strategies for ocular surface inflammation, such as DE disease.

Docosahexaenoic acid, protectins and dry eye

To report recent data on the potential role of omega-3 fatty acids, in particular docosahexaenoic acid and its derivatives, in the treatment of dry eye syndrome. Dietary supplementation with polyunsaturated fatty acids yields positive results in the improvement of dry eye signs and symptoms. Although several studies have shown this, evidence is still lacking as to which fatty acid or what combination constitutes the most effective treatment. Studies show that treatment with alpha-linoleic acid reduces dry eye-induced inflammation. Eicosapentaenoic acid and docosahexaenoic acid derivatives, particularly resolvin E1 (RvE1) and neuroprotectin D1, appear to be responsible for docosahexaenoic acid's anti-inflammatory effect. This is supported in a study in which topical RvE1 resulted in decreased inflammation in a mouse dry eye model. Topical administration of pigment epithelium-derived factor in combination with docosahexaenoic acid accelerates the regeneration of corneal nerves after their damage during corneal surgery, promoting the return of sensitivity and reducing the signs of dry eye. This combined treatment also reduces objective signs of dry eye, such as rose bengal staining. No firm recommendations can be made regarding optimal dietary supplementation of essential fatty acids that benefit dry eye patients. On the basis of animal data and preliminary human studies, docosahexaenoic acid and its derivatives appear to be a safe, effective topical treatment for dry eye patients. This may result from their role in the resolution of inflammation and the regeneration of damaged corneal nerves.