Engineered Knockout of TRPA1 Inhibits Laser-Induced Choroidal Neovascularization Along With Associated TGFß1 Expression and Neutrophil Infiltration.

We examined the effects of gene ablation and chemical inhibition of transient receptor potential ankyrin 1 (TRPA1) on the growth of experimental argon laser-induced choroidal neovascularization (CNV) in mice. CNV was induced in the eyes of 6- to 8-week-old TRPA1-null (knockout [KO]) and wild-type (WT) mice by argon laser irradiation. Gene expression analysis was performed in laser-injured tissues at days 1 and 3. CNV growth was evaluated at day 14. Reciprocal bone marrow transplantation was performed between each genotype to identify the components responsible for either recipient tissue or bone marrow-derived inflammatory cells. Our results show that laser irradiation successfully induced CNV growth at the site of laser injury. The size of induced CNV was significantly smaller in KO mice than in WT mice at day 14, as determined by angiography with fluorescein isothiocyanate-dextran. Invasion of neutrophils, but not macrophages, was suppressed in association with suppression of the expression of transforming growth factor ß1 and interleukin 6 in laser-irradiated KO tissue. Bone marrow transplantation indicated that the genotype of the recipient mouse, but not of inflammatory cells, is attributable to the KO phenotype. Systemic administration of a TRPA1 antagonist also reduced the CNV in a WT mouse. In conclusion, TRPA1 signaling in local cells is involved in growth of laser-induced CNV. The phenotype was not attributable to vascular endothelial cells and inflammatory cells. Blocking TRPA1 signal may therefore be a potential treatment strategy for CNV-related ocular diseases.

Tenascins and osteopontin in biological response in cornea.

The structural composition, integrity and regular curvature of the cornea contribute to the maintenance of its transparency and vision. Disruption of its integrity caused by injury results in scarring, inflammation and neovascularization followed by losses in transparency. These sight compromising effects is caused by dysfunctional corneal resident cell responses induced by the wound healing process. Upregulation of growth factors/cytokines and neuropeptides affect development of aberrant behavior. These factors trigger keratocytes to first transform into activated fibroblasts and then to myofibroblasts. Myofibroblasts express extracellular matrix components for tissue repair and contract the tissue to facilitate wound closure. Proper remodeling following primary repair is critical for restoration of transparency and visual function. Extracellular matrix components contributing to the healing process are divided into two groups; a group of classical tissue structural components and matrix macromolecules that modulate cell behaviors/activities besides being integrated into the matrix structure. The latter components are designated as matricellular proteins. Their functionality is elicited through mechanisms which modulate the scaffold integrity, cell behaviors, activation/inactivation of either growth factors or cytoplasmic signaling regulation. We discuss here the functional roles of matricellular proteins in mediating injury-induced corneal tissue repair. The roles are described of major matricellular proteins, which include tenascin C, tenascin X and osteopontin. Focus is directed towards dealing with their roles in modulating individual activities of wound healing-related growth factors, e. g., transforming growth factor ß (TGF ß). Modulation of matricellular protein functions could encompass a potential novel strategy to improve the outcome of injury-induced corneal wound healing.

Calcipotriol Attenuates Form Deprivation Myopia Through a Signaling Pathway Parallel to TGF-ß2-Induced Increases in Collagen Expression.

Purpose: To determine the role of calcipotriol, a vitamin D3 analogue, in myopia development and altering the expression of scleral α1 chain of type I collagen (Col1α1) in mice. We also aimed to identify if the signaling pathway mediating the above changes is different from the one involved in transforming growth factor ß2 (TGF-ß2)-mediated increases of COL1A1 in cultured human scleral fibroblasts (HSFs). Methods: C57BL/6J mice were either intraperitoneally injected with calcipotriol and subjected to form deprivation (FD) or exposed to normal refractive development for 4 weeks. Scleral vitamin D receptor (Vdr) expression was knocked down using a Sub-Tenon's capsule injection of an adeno-associated virus-packaged short hairpin RNA (AAV8-shRNA). Refraction and biometric measurements evaluated myopia development. A combination of knockdown and induction strategies determined the relative contributions of the vitamin D3 and the TGF-ß2 signaling pathways in modulating COL1A1 expression in HSFs. Results: Calcipotriol injections suppressed FD-induced myopia (FDM), but it had no significant effect on normal refractive development. AAV8-shRNA injection reduced Vdr mRNA expression by 42% and shifted the refraction toward myopia (-3.15 ± 0.99D, means ± SEM) in normal eyes. In HSFs, VDR knockdown reduced calcipotriol-induced rises in COL1A1 expression, but it did not alter TGF-ß2-induced increases in COL1A1 expression. Additionally, TGF-ß2 augmented calcipotriol-induced rises in COL1A1 expression. TGF-ß receptor (TGFBRI/II) knockdown blunted TGF-ß2-induced increases in COL1A1 expression, whereas calcipotriol-induced increases in VDR and COL1A1 expression levels were unaltered. Conclusions: Scleral vitamin D3 inhibits myopia development in mice, potentially by activating a VDR-dependent signaling pathway and increasing scleral COL1A1 expression levels.

Inhibition of CD146 lessens uveal melanoma progression through reducing angiogenesis and vasculogenic mimicry.

PURPOSE: Anti-angiogenesis drug therapy is ineffective in treating uveal melanoma since it only targets angiogenesis leaving vasculogenic mimicry aside. There is no effective clinical strategy targeting vasculogenic mimicry, yet. We show here that CD146 is a novel target to inhibit uveal melanoma progression since it regulates both uveal melanoma angiogenesis and vasculogenic mimicry activity. METHODS: CD146 inhibition was achieved with its specific siRNAs or antibody AA98. Tube formation and migration of primary human retinal microvascular endothelial cells and tube-like structure formation, migration, invasion of uveal melanoma cells were evaluated after CD146 inhibition. The underlying mechanisms were investigated by Western blot and immunofluorescence. Finally, uveal melanoma cells were injected subretinally into the eyes of nude mice and AA98 was administrated. Tumor size was revealed by H&E staining, and angiogenesis and vasculogenic mimicry were evaluated with CD31-PAS staining. RESULTS: CD146 inhibition induced declines in tube formation and migration of primary human retinal microvascular endothelial cells and tube-like structure formation of uveal melanoma cells. CD146 mediated VEGFR/AKT/p38/NF-κB and FAK/VE-cadherin signal cascades were partially responsible for these biological effects. CD146 blockade by siRNA or AA98 also resulted in inhibition of migration and invasion as well as EMT process of uveal melanoma cells. The physiological relevance of such declines was confirmed by showing that AA98 treatment markedly suppressed the tumor growth, angiogenesis and vasculogenic mimicry induced by implantation of uveal melanoma cells into the eyes of nude mice. CONCLUSIONS: CD146 is a novel mediator of both angiogenesis and vasculogenic mimicry in uveal melanoma. Its antibody AA98 has the potency to be developed as a new antibody drug for treating uveal melanoma. Our results warrant further assessment of CD146 as a potential target to improve therapeutic management of uveal melanoma in a clinical setting.

Dysfunction of VIPR2 leads to myopia in humans and mice.

BACKGROUND: Myopia is the leading cause of refractive errors. As its pathogenesis is poorly understood, we determined if the retinal VIP-VIPR2 signalling pathway axis has a role in controlling signalling output that affects myopia development in mice. METHODS: Association analysis meta-study, single-cell transcriptome, bulk RNA sequencing, pharmacological manipulation and VIPR2 gene knockout studies were used to clarify if changes in the VIP-VIPR2 signalling pathway affect refractive development in mice. RESULTS: The SNP rs6979985 of the VIPR2 gene was associated with high myopia in a Chinese Han cohort (randomceffect model: p=0.013). After either 1 or 2 days' form deprivation (FD) retinal VIP mRNA expression was downregulated. Retinal single-cell transcriptome sequencing showed that VIPR2 was expressed mainly by bipolar cells. Furthermore, the cAMP signalling pathway axis was inhibited in some VIPR2+ clusters after 2 days of FD. The selective VIPR2 antagonist PG99-465 induced relative myopia, whereas the selective VIPR2 agonist Ro25-1553 inhibited this response. In Vipr2 knockout (Vipr2-KO) mice, refraction was significantly shifted towards myopia (p<0.05). The amplitudes of the bipolar cell derived b-waves in 7-week-old Vipr2-KO mice were significantly larger than those in their WT littermates (p<0.05). CONCLUSIONS: Loss of VIPR2 function likely compromises bipolar cell function based on presumed changes in signal transduction due to altered signature electrical wave activity output in these mice. As these effects correspond with increases in form deprivation myopia (FDM), the VIP-VIPR2 signalling pathway axis is a viable novel target to control the development of this condition.

High-Fat Diet Induces Inflammation of Meibomian Gland.

Purpose: To determine if a high-fat diet (HFD) induces meibomian gland (MG) inflammation in mice. Methods: Male C57BL/6J mice were fed a standard diet (SD), HFD, or HFD supplemented with the peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist rosiglitazone for various durations. Body weight, blood lipid levels, and eyelid changes were monitored at regular intervals. MG sections were subjected to hematoxylin and eosin staining, LipidTox staining, TUNEL assay, and immunostaining. Quantitative RT-PCR and western blot analyses were performed to detect relative gene expression and signaling pathway activation in MGs. Results: MG acinus accumulated more lipids in the mice fed the HFD. Periglandular CD45-positive and F4/80-positive cell infiltration were more evident in the HFD mice, and they were accompanied by upregulation of inflammation-related cytokines. PPAR-γ downregulation accompanied activation of the mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways in the HFD mice. There was increased acini cell apoptosis and mitochondria damage in mice fed the HFD. MG inflammation was ameliorated following a shift to the standard diet and rosiglitazone treatment in the mice fed the HFD. Conclusions: HFD-induced declines in PPAR-γ expression and MAPK and NF-κB signaling pathway activation resulted in MG inflammation and dysfunction in mice.

Ascorbate-induced oxidative stress mediates TRP channel activation and cytotoxicity in human etoposide-sensitive and -resistant retinoblastoma cells.

There are indications that pharmacological doses of ascorbate (Asc) used as an adjuvant improve the chemotherapeutic management of cancer. This favorable outcome stems from its cytotoxic effects due to prooxidative mechanisms. Since regulation of intracellular Ca2+ levels contributes to the maintenance of cell viability, we hypothesized that one of the effects of Asc includes disrupting regulation of intracellular Ca2+ homeostasis. Accordingly, we determined if Asc induced intracellular Ca2+ influx through activation of pertussis sensitive Gi/o-coupled GPCR which in turn activated transient receptor potential (TRP) channels in both etoposide-resistant and -sensitive retinoblastoma (WERI-Rb1) tumor cells. Ca2+ imaging, whole-cell patch-clamping, and quantitative real-time PCR (qRT-PCR) were performed in parallel with measurements of RB cell survival using Trypan Blue cell dye exclusion. TRPM7 gene expression levels were similar in both cell lines whereas TRPV1, TRPM2, TRPA1, TRPC5, TRPV4, and TRPM8 gene expression levels were downregulated in the etoposide-resistant WERI-Rb1 cells. In the presence of extracellular Ca2+, 1 mM Asc induced larger intracellular Ca2+ transients in the etoposide-resistant WERI-Rb1 than in their etoposide-sensitive counterpart. With either 100 µM CPZ, 500 µM La3+, 10 mM NAC, or 100 µM 2-APB, these Ca2+ transients were markedly diminished. These inhibitors also had corresponding inhibitory effects on Asc-induced rises in whole-cell currents. Pertussis toxin (PTX) preincubation blocked rises in Ca2+ influx. Microscopic analyses showed that after 4 days of exposure to 1 mM Asc cell viability fell by nearly 100% in both RB cell lines. Taken together, one of the effects underlying oxidative mediated Asc-induced WERI-Rb1 cytotoxicity stems from its promotion of Gi/o coupled GPCR mediated increases in intracellular Ca2+ influx through TRP channels. Therefore, designing drugs targeting TRP channel modulation may be a viable approach to increase the efficacy of chemotherapeutic treatment of RB. Furthermore, Asc may be indicated as a possible supportive agent in anti-cancer therapies.

Alteration of expression pattern of transient receptor potential vanilloid 2 and transient receptor potential vanilloid 3 in ocular surface neoplasm.

PURPOSE: We determined if the immunohistochemical expression pattern of transient receptor potential vanilloid (TRPV) family members and TRP ankyrin 1 (TRPA1) differs among a healthy conjunctival epithelium and diseased epithelia. MATERIALS AND METHODS: Subjects include a normal conjunctival epithelium, pterygium epithelium, epithelial dysplasia or carcinoma in situ. RESULTS: TRPV1, TRPV4 or TRPA1 was detected in both the cytoplasm and nuclei, or in either the nuclei or cytoplasm, of these different epithelial layers, respectively. There was no difference in the expression pattern of these three TRP isoforms. On the other hand, the expression patterns of TRPV2 and TRPV3 differed dramatically among these different subjects. TRPV2 was observed in the basal layer epithelium of a normal conjunctiva and pterygium. Its pattern was scattered in this region, although TRPV2 was absent throughout most of the dysplastic epithelium. TRPV2 was detected only in some of the suprabasal epithelial cells of a carcinoma in situ. TRPV3 was faintly detected in the cytoplasm of all the cell layers and also in the nuclei of some of the basal cells in a normal conjunctiva and in the pterygia epithelium, while in situ it was uniformly expressed in all of the dysplasia and carcinoma nuclei in all epithelial cell layers. CONCLUSION: These results suggest that TRPV2 and TRPV3 expression pattern analysis might be potential diagnostic markers of ocular surface epithelial disorders.

High-Fat Diet-Induced Functional and Pathologic Changes in Lacrimal Gland.

The lacrimal gland is critical for maintaining the homeostasis of the ocular surface microenvironment through secreting aqueous tears in mammals. Many systemic diseases such as Sjögren syndrome, rheumatoid arthritis, and diabetes can alter the lacrimal gland function, eventually resulting in aqueous tear-deficient dry eye. Here, a high-fat diet (HFD) experimental mouse model was used to clarify how hyperlipidemia affects lacrimal gland function. Aqueous tear secretion fell about 50% after 1 month on a HFD. Lipid droplets accumulated in the matrix and acinar cells of the lacrimal gland after this period, along with changes in the lipid metabolism, changes in gene expression levels, and disruption of fatty acid oxidative activity. Immune cell infiltration and rises in the gene expression levels of the inflammation-related cytokines Il1ß, Tnfα, Tsg6, Il10, Mmp2, and Mmp9 were found. HFD also induced mitochondrial hypermegasoma, increased apoptosis, and decreased lacrimal gland acinar cell proliferation. Replacement of the HFD with the standard diet partially reversed pathologic changes in the lacrimal gland. Similarly, supplementing the HFD with fenofibrate also partially reversed the inhibited tear secretion and reduced lipid accumulation, inflammation, and oxidative stress levels. The authors conclude that a HFD induces pathophysiological changes and functional decompensation of the lacrimal gland. Therefore, ingestion of a HFD may be a causative factor of dry eye disease.

Anti-fibrotic effects of rosmarinic acid on Tenon's capsule fibroblasts stimulated with TGF-ß: therapeutic potential in ocular surgery.

PURPOSE: Collagen deposition and myofibroblast differentiation are critical factors related to excessive scarring in ocular surgeries. This study evaluated the anti-fibrotic activity of rosmarinic acid on rabbit Tenon's capsule fibroblasts stimulated with transforming growth factor- ß2. METHODS: Primary cultures of rabbit Tenon's capsule fibroblasts were treated with various concentrations of rosmarinic acid for 12 h, in the presence and absence of transforming growth factor-ß2. After 48 h, the proliferation index of rabbit Tenon's capsule fibroblasts and the differentiation of myofibroblasts were investigated through immunofluorescence staining for proliferating cell nuclear antigen and alpha smooth muscle actin. An automated cell counter and colorimetric metabolic activity assay were used to evaluate cell number and viability. Collagen expression and production were determined by quantitative real-time polymerase chain reaction and hydroxyproline assay, respectively. RESULTS: Unstimulated rabbit Tenon's capsule fibroblasts treated with any concentration of rosmarinic acid exhibited diminished collagen expression (p<0.01) but showed no differences in proliferation index. Transforming growth factor-ß2 exposure induced myofibroblast differentiation and increased collagen production. Exposure to rosmarinic acid at 1.0 and 3.0 µM concentrations reduced the proliferation index (p<0.02), as well as the collagen expression and hydroxyproline content (p<0.05). Exposure to 3.0 µM rosmarinic acid reduced viability (p=0.035) in unstimulated rabbit Tenon's capsule fibroblasts and cell numbers (p=0.001) in both stimulated and unstimulated rabbit Tenon's capsule fibroblast cultures. CONCLUSIONS: Exposure to 1.0 µM rosmarinic acid was noncytotoxic and led to reduced collagen expression and proliferation of stimulated rabbit Tenon's capsule fibroblasts. These findings suggest that rosmarinic acid is a relatively non-injurious anti-fibrotic compound to rabbit Tenon's capsule fibroblasts, with potential application as an adjunctive agent in ocular procedures, particularly in glaucoma surgeries.

Anti-fibrotic effects of rosmarinic acid on Tenon's capsule fibroblasts stimulated with TGF-ß: therapeutic potential in ocular surgery / Efeito antifibrótico do Ácido Rosmarínico sobre os fibroblastos da Cápsula de Tenon estimulados com TGF-beta2: potencial terapêutico na cirurgia ocular

ABSTRACT Purpose: Collagen deposition and myofibroblast differentiation are critical factors related to excessive scarring in ocular surgeries. This study evaluated the anti-fibrotic activity of rosmarinic acid on rabbit Tenon's capsule fibroblasts stimulated with transforming growth factor- β2. Methods: Primary cultures of rabbit Tenon's capsule fibroblasts were treated with various concentrations of rosmarinic acid for 12 h, in the presence and absence of transforming growth factor-β2. After 48 h, the proliferation index of rabbit Tenon's capsule fibroblasts and the differentiation of myofibroblasts were investigated through immunofluorescence staining for proliferating cell nuclear antigen and alpha smooth muscle actin. An automated cell counter and colorimetric metabolic activity assay were used to evaluate cell number and viability. Collagen expression and production were determined by quantitative real-time polymerase chain reaction and hydroxyproline assay, respectively. Results: Unstimulated rabbit Tenon's capsule fibroblasts treated with any concentration of rosmarinic acid exhibited diminished collagen expression (p<0.01) but showed no differences in proliferation index. Transforming growth factor-β2 exposure induced myofibroblast differentiation and increased collagen production. Exposure to rosmarinic acid at 1.0 and 3.0 µM concentrations reduced the proliferation index (p<0.02), as well as the collagen expression and hydroxyproline content (p<0.05). Exposure to 3.0 µM rosmarinic acid reduced viability (p=0.035) in unstimulated rabbit Tenon's capsule fibroblasts and cell numbers (p=0.001) in both stimulated and unstimulated rabbit Tenon's capsule fibroblast cultures. Conclusions: Exposure to 1.0 µM rosmarinic acid was noncytotoxic and led to reduced collagen expression and proliferation of stimulated rabbit Tenon's capsule fibroblasts. These findings suggest that rosmarinic acid is a relatively non-injurious anti-fibrotic compound to rabbit Tenon's capsule fibroblasts, with potential application as an adjunctive agent in ocular procedures, particularly in glaucoma surgeries.

RESUMO Objetivo: A deposição de colágeno e a diferenciação de miofibroblastos são fatores chaves relacionados à cicatrização excessiva em cirurgias oculares. Este estudo avaliou a atividade anti-fibrótica do ácido rosmarínico nos fibroblastos da cápsula de Tenon de coelhos estimulados com o fator de crescimento transformador-β2. Métodos: Culturas primárias de fibroblastos da cápsula de Tenon de coelhos foram tratadas com várias concentrações de ácido rosmarínico por 12h, na presença e na ausência do fator de crescimento transformador-β2. Após 48h, o índice de proliferação dos fibroblastos da cápsula de Tenon de coelhos e a diferenciação dos miofibroblastos foram investigados por coloração por imunofluorescência para proliferação de antígeno nuclear celular e α-actina de músculo liso, respectivamente. Um contador automático de células e um ensaio de atividade metabólica colorimétrica foram utilizados para avaliar o número e a viabilidade das células. A expressão e produção do colágeno foram determinadas por reação quantitativa em cadeia da polimerase em tempo real e ensaio de hidroxiprolina, respectivamente. Resultados: Fibroblastos da cápsula de Tenon de coelhos não estimulados tratados com qualquer concentração de ácido rosmarínico exibiram diminuição de colágeno (p<0,01), mas não mostraram diferenças no índice de proliferação. A exposição ao fator de crescimento transformador-β2 induziu a diferenciação de miofibroblastos e aumentou a produção de colágeno. A exposição ao ácido rosmarínico nas concentrações de 1,0 e 3,0 µM reduziu o índice de proliferação (p<0,02), bem como a expressão de colágeno e a quantificação de hidroxiprolina (p<0.05). A exposição a 3,0 µM de ácido rosmarínico reduziu a viabilidade (p=0,035) de fibroblastos da cápsula de Tenon de coelhos não estimulados e o número de células (p=0,001) em culturas de fibroblastos da cápsula de Tenon de coelhos estimuladas e não estimuladas. Conclusões: A exposição ao ácido rosmarínico 1,0 µM foi não citotóxica e levou à expressão reduzida de colágeno e menor proliferação de fibroblastos da cápsula de Tenon estimulados pelo fator de crescimento transformador-β2. Esses achados sugerem que o ácido rosmarínico é um composto antifibrótico relativamente não lesivo aos fibroblastos da cápsula de Tenon de coelhos, com potencial aplicação como agente adjuvante em procedimentos oculares, particularmente em cirurgias de glaucoma.

Crosstalk between EP2 and PPARα Modulates Hypoxic Signaling and Myopia Development in Guinea Pigs.

Purpose: Cyclic adenosine monophosphate (cAMP) and peroxisome proliferator-activated receptor alpha (PPARα) levels mediate extracellular matrix (ECM) changes by altering the levels of hypoxia-inducible factor 1-alpha (HIF-1α) in various tissues. We aimed to determine, in the sclera of guinea pigs, whether a prostanoid receptor (EP2)-linked cAMP modulation affects PPARα and HIF-1α signaling during myopia. Methods: Three-week-old guinea pigs (n = 20 in each group), were monocularly injected with either an EP2 agonist (butaprost 1 µmol/L/10 µmol/L), an antagonist (AH6809 10 µmol/L/30 µmol/L) or a vehicle solution for two weeks during normal ocular growth. Separate sets of animals received these injections and underwent form deprivation (FD) simultaneously. Refraction and axial length (AL) were measured at two weeks, followed by scleral tissue isolation for quantitative PCR (qPCR) analysis (n = 10) and cAMP detection (n = 10) using a radioimmunoassay. Results: Butaprost induced myopia development during normal ocular growth, with proportional increases in AL and cAMP levels. FD did not augment the magnitude of myopia or cAMP elevations in these agonist-injected eyes. AH6809 suppressed cAMP increases and myopia progression during FD, but had no effect in a normal visual environment. Of the diverse set of 27 genes related to cAMP, PPARα and HIF-1α signaling and ECM remodeling, butaprost differentially regulated 15 of them during myopia development. AH6809 injections during FD negated such differential gene expressions. Conclusion: EP2 agonism increased cAMP and HIF-1α signaling subsequent to declines in PPARα and RXR mRNA levels, which in turn decreased scleral fibrosis and promoted myopia. EP2 antagonism instead inhibited each of these responses. Our data suggest that EP2 suppression may sustain scleral ECM structure and inhibit myopia development.

Tissue engineered corneal epithelium derived from clinical-grade human embryonic stem cells.

PURPOSE: To construct tissue engineered corneal epithelium from a clinical-grade human embryonic stem cells (hESCs) and investigate the dynamic gene profile and phenotypic transition in the process of differentiation. METHODS: A stepwise protocol was applied to induce differentiation of clinical-grade hESCs Q-CTS-hESC-1 and construct tissue engineered corneal epithelium. Single cell RNA sequencing (scRNA-seq) analysis was performed to monitor gene expression and phenotypic changes at different differentiation stages. Immunostaining, real-time quantitative PCR and Western blot analysis were conducted to detect gene and protein expressions. After subcutaneous transplantation into nude mice to test the biosafety, the epithelial construct was transplanted in a rabbit corneal limbal stem cell deficiency (LSCD) model and followed up for eight weeks. RESULTS: The hESCs were successfully induced into epithelial cells. scRNA-seq analysis revealed upregulation of ocular surface epithelial cell lineage related genes such as TP63, Pax6, KRT14, and activation of Wnt, Notch, Hippo, and Hedgehog signaling pathways during the differentiation process. Tissue engineered epithelial cell sheet derived from hESCs showed stratified structure and normal corneal epithelial phenotype with presence of clonogenic progenitor cells. Eight weeks after grafting the cell sheet onto the ocular surface of LSCD rabbit model, a full-thickness continuous corneal epithelium developed to fully cover the damaged areas with normal limbal and corneal epithelial phenotype. CONCLUSION: The tissue engineered corneal epithelium generated from a clinical-grade hESCs may be feasible in the treatment of limbal stem cell deficiency.

Sensory nerve supports epithelial stem cell function in healing of corneal epithelium in mice: the role of trigeminal nerve transient receptor potential vanilloid 4.

In order to understand the pathobiology of neurotrophic keratopathy, we established a mouse model by coagulating the first branch of the trigeminal nerve (V1 nerve). In our model, the sensory nerve in the central cornea disappeared and remaining fibers were sparse in the peripheral limbal region. Impaired corneal epithelial healing in the mouse model was associated with suppression of both cell proliferation and expression of stem cell markers in peripheral/limbal epithelium as well as a reduction of transient receptor potential vanilloid 4 (TRPV4) expression in tissue. TRPV4 gene knockout also suppressed epithelial repair in mouse cornea, although it did not seem to directly modulate migration of epithelium. In a co-culture experiment, TRPV4-introduced KO trigeminal ganglion upregulated nerve growth factor (NGF) in cultured corneal epithelial cells, but ganglion with a control vector did not. TRPV4 gene introduction into a damaged V1 nerve rescues the impairment of epithelial healing in association with partial recovery of the stem/progenitor cell markers and upregulation of cell proliferation and of NGF expression in the peripheral/limbal epithelium. Gene transfer of TRPV4 did not accelerate the regeneration of nerve fibers. Sensory nerve TRPV4 is critical to maintain stemness of peripheral/limbal basal cells, and is one of the major mechanisms of homeostasis maintenance of corneal epithelium.

Role of Cyclic Adenosine Monophosphate in Myopic Scleral Remodeling in Guinea Pigs: A Microarray Analysis.

Purpose: Myopia induction accompanies increased scleral cyclic adenosine phosphate (cAMP) levels and collagen degradation in mammalian models. We compared the scleral gene expression changes following monocular form deprivation (FD) with those induced by adenylate cyclase activation with forskolin (FSK) in guinea pigs. Methods: Guinea pigs were assigned to FD, FSK-treated, and age-matched (AM) control groups. FSK was injected monocularly into the inferior palpebral subconjunctiva daily for 4 days. After scleral RNA extraction, a gene microarray scanner and software were used to evaluate the gene expression patterns, followed by pathway analysis using Gene Ontology tools. Quantitative PCR (qPCR) was used to analyze the expression of 10 candidate genes in separate sets of form-deprived, vehicle-injected, and AM animals. Results: FSK injections differentially regulated 13 collagen subtypes compared to AM and FD groups. FSK also downregulated Acta2 and Tgf-ß2 compared to the AM eyes. Collagen subtypes and Acta2 underwent larger downregulation in the FSK group than during FD. FSK differentially regulated Rarb, Rxrg, Fzd5, Ctnnd2, Dkk2, and Dkk3, which have been linked to ocular growth. Only a few genes were differentially expressed between the FD and AM groups. There was 80% agreement in the direction of gene regulation between microarray and qPCR results. No significant differences were identified between vehicle-injected and AM eyes. Conclusions: Collagen, a major scleral extracellular matrix component, is degraded during myopia. Given that FSK and FD both promote myopia through increased collagen degradation, targeting cAMP signaling pathway genes could suppress myopia development.

Sleep Deprivation Induces Dry Eye Through Inhibition of PPARα Expression in Corneal Epithelium.

Purpose: To determine if sleep deprivation induces dry eye through altering peroxisome proliferator-activated receptor alpha (PPARα) expression in mice. Methods: The "stick over water" sleep deprivation-induced dry eye (SDE) model evaluated PPARα involvement in inducing this condition. Scanning electron microscopy (SEM) examined microvilli morphology in superficial corneal epithelial cells (SCECs) in SDE and PPARα-/- mice. Quantitative RT-PCR (qRT-PCR) and Western blot (WB) or immunostaining evaluated PPARα, carnitine palmitoyl transferase 1α (CPT1α), and transient receptor potential vanilloid 6 (TRPV6) expression levels and Ezrin phosphorylation status. Hematoxylin-eosin and Oil Red O staining characterized meibomian gland morphology and corneal lipid accumulation, respectively. Phenol red cotton threads measured tear production. In cultured corneal epithelial sheets, qRT-PCR, WB, and SEM determined the individual effects of fenofibrate and MK886 (PPARα agonist and antagonist, respectively) on PPARα, TRPV6 expression, and SCEC microvilli morphology. Results: Corneal epithelial lipid accumulation, microvilli morphologic changes, and decreased tear production were associated with marked declines in PPARα, CPT1α, and TRPV6 expression levels as well as Ezrin phosphorylation status, whereas meibomian glands were unaltered in SDE mice. These effects of SDE mice mimicked those in their nonstressed PPARα-/-counterpart. Topical application of fenofibrate reversed these effects in SDE corneas. In cultured corneal epithelial sheets, fenofibrate increased PPARα and TRPV6 gene and protein expression levels and restored microvilli morphology, whereas MK886 attenuated these changes. Conclusions: Sleep deprivation induces dry eye through abnormal SCEC microvilli morphology, which is caused by sequential downregulation of PPARα, TRPV6 expression, and Ezrin phosphorylation status in mice.

Function of meibomian gland: Contribution of proteins.

The meibomian gland is the major contributor to the tear film lipid layer. It is generally accepted that meibomian gland secretions, i.e, meibum, play a critical role in the homeostasis of the tear film. Lipid components of meibum and their structure, as well as functions were intensively studied. However, the proteins from meibum have not attracted enough attention. This review summarizes current knowledge about protein components of the meibum, particularly their function on tear film and ocular surface, and changes in the proteins during meibomian gland dysfunction (MGD).

Ectodysplasin A protein promotes corneal epithelial cell proliferation.

The EDA gene encodes ectodysplasin A (Eda), which if mutated causes X-linked hypohidrotic ectodermal dysplasia (XLHED) disease in humans. Ocular surface changes occur in XLHED patients whereas its underlying mechanism remains elusive. In this study, we found Eda was highly expressed in meibomian glands, and it was detected in human tears but not serum. Corneal epithelial integrity was defective and the thickness was reduced in the early postnatal stage of Eda mutant Tabby mice. Corneal epithelial cell proliferation decreased and the epithelial wound healing was delayed in Tabby mice, whereas it was restored by exogenous Eda. Eda exposure promoted mouse corneal epithelial wound healing during organ culture, whereas scratch wound assay showed that it did not affect human corneal epithelial cell line migration. Epidermal growth factor receptor (EGFR), phosphorylated EGFR (p-EGFR), and phosphorylated ERK1/2 (p-ERK) were down-regulated in Tabby mice corneal epithelium. Eda treatment up-regulated the expression of Ki67, EGFR, p-EGFR, and p-ERK in human corneal epithelial cells in a dose-dependent manner. In conclusion, Eda protein can be secreted from meibomian glands and promotes corneal epithelial cell proliferation through regulation of the EGFR signaling pathway. Eda release into the tears plays an essential role in the maintenance of corneal epithelial homeostasis.