Publications by authors named "Wai Kit Chu"

52 Publications

Enhancers are activated by p300/CBP activity-dependent PIC assembly, RNAPII recruitment, and pause release.

Mol Cell 2021 Mar 17. Epub 2021 Mar 17.

Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen 2200, Denmark. Electronic address:

The metazoan-specific acetyltransferase p300/CBP is involved in activating signal-induced, enhancer-mediated transcription of cell-type-specific genes. However, the global kinetics and mechanisms of p300/CBP activity-dependent transcription activation remain poorly understood. We performed genome-wide, time-resolved analyses to show that enhancers and super-enhancers are dynamically activated through p300/CBP-catalyzed acetylation, deactivated by the opposing deacetylase activity, and kinetic acetylation directly contributes to maintaining cell identity at very rapid (minutes) timescales. The acetyltransferase activity is dispensable for the recruitment of p300/CBP and transcription factors but essential for promoting the recruitment of TFIID and RNAPII at virtually all enhancers and enhancer-regulated genes. This identifies pre-initiation complex assembly as a dynamically controlled step in the transcription cycle and reveals p300/CBP-catalyzed acetylation as the signal that specifically promotes transcription initiation at enhancer-regulated genes. We propose that p300/CBP activity uses a "recruit-and-release" mechanism to simultaneously promote RNAPII recruitment and pause release and thereby enables kinetic activation of enhancer-mediated transcription.
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http://dx.doi.org/10.1016/j.molcel.2021.03.008DOI Listing
March 2021

Epigallocatechin-3-gallate increases autophagic activity attenuating TGF-β1-induced transformation of human Tenon's fibroblasts.

Exp Eye Res 2021 Mar 16;204:108447. Epub 2021 Jan 16.

Department of Ophthalmology, Guangdong Eye Institute, Guangdong Provincial People's Hospital and Guangdong Academy of Medical Sciences. Guangzhou, China; The Second School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong, China. Electronic address:

We previously found that epigallocatechin-3-gallate (EGCG) could inhibit the myofibroblast transformation of human Tenon's fibroblasts, however, the underlying mechanism remained unclear. We therefore investigated whether the autophagic regulation involved in the anti-fibrotic function of EGCG. The fibroblasts were subjected to transforming growth factor beta-1 (TGF-β1) induction followed by EGCG treatments. The autophagic flux was examined by transmission electron microscopy and autophagic flux analysis. The levels of autophagy-related proteins (LC3β and p62) and alpha-smooth muscle actin (α-SMA) were measured by Western blot and immunofluorescence. Results showed that TGF-β1 partially inhibited the autophagic function of Tenon's fibroblasts. But this inhibition effect was rescued by LY2157299, a TGF-βR1 selective inhibitor. Compared with the cells treated with TGF-β1 alone, EGCG treatments increased the amount of autophagosomes and autolysosomes, evaluated the ratio of LC3-II to LC3-I and decreased p62 level. Our results indicated that EGCG could recover the activity of autophagy in the TGF-β1-treated cells. Moreover, treatments with EGCG significantly decreased the α-SMA expression. Taken together, these findings revealed that autophagic regulation involved in the action of EGCG against TGF-β1-induced transformation of Tenon's fibroblasts. Through increasing intracellular autophagy, EGCG could be a potential anti-fibrotic reagent for preventing subconjunctival fibrosis after glaucoma filtration surgery.
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http://dx.doi.org/10.1016/j.exer.2021.108447DOI Listing
March 2021

RB Regulates DNA Double Strand Break Repair Pathway Choice by Mediating CtIP Dependent End Resection.

Int J Mol Sci 2020 Dec 1;21(23). Epub 2020 Dec 1.

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.

Inactivation of the retinoblastoma tumor suppressor gene () leads to genome instability, and can be detected in retinoblastoma and other cancers. One damaging effect is causing DNA double strand breaks (DSB), which, however, can be repaired by homologous recombination (HR), classical non-homologous end joining (C-NHEJ), and micro-homology mediated end joining (MMEJ). We aimed to study the mechanistic roles of RB in regulating multiple DSB repair pathways. Here we show that HR and C-NHEJ are decreased, but MMEJ is elevated in RB-depleted cells. After inducing DSB by camptothecin, RB co-localizes with CtIP, which regulates DSB end resection. RB depletion leads to less RPA and native BrdU foci, which implies less end resection. In RB-depleted cells, less CtIP foci, and a lack of phosphorylation on CtIP Thr847, are observed. According to the synthetic lethality principle, based on the altered DSB repair pathway choice, after inducing DSBs by camptothecin, RB depleted cells are more sensitive to co-treatment with camptothecin and MMEJ blocker poly-ADP ribose polymerase 1 (PARP1) inhibitor. We propose a model whereby RB can regulate DSB repair pathway choice by mediating the CtIP dependent DNA end resection. The use of PARP1 inhibitor could potentially improve treatment outcomes for RB-deficient cancers.
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http://dx.doi.org/10.3390/ijms21239176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7730402PMC
December 2020

Exposure to Secondhand Smoke in Children is Associated with a Thinner Retinal Nerve Fiber Layer: The Hong Kong Children Eye Study.

Am J Ophthalmol 2021 03 29;223:91-99. Epub 2020 Oct 29.

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China; Department of Ophthalmology and Visual Sciences, Prince of Wales Hospital, Hong Kong; Hong Kong Eye Hospital, Hong Kong SAR, China; Department of Ophthalmology, Hong Kong Children's Hospital SAR, China. Electronic address:

Purpose: We sought to assess the effects of exposure to secondhand smoke (SHS) on peripapillary retinal nerve fiber layer (p-RNFL) thickness in children.

Design: Cross-sectional study.

Methods: Children 6-8 years of age were consecutively recruited from the population-based Hong Kong Children Eye Study. All participants received comprehensive ophthalmic examinations and p-RNFL thickness was measured by spectral-domain optical coherence tomography. SHS data were derived from a validated questionnaire. Associations between p-RNFL thickness and SHS exposure status, number of smokers in the family, and quantity of smoking in the family were determined by multivariate linear regression after adjusting for potential confounders.

Results: Among the Hong Kong Children Eye Study cohort (n = 3,103), approximately one-third of children were exposed to SHS (35.4%, n = 1,097). Compared to those without exposure to SHS, children exposed to SHS had similar age (P = .83), gender (P = .17), body mass index (P = .44), birth weight (P = .23), and axial length (P = .34), but had lower family income (P < .001) and lower parental education level (P < .001). After adjusting for all the above factors, exposure to SHS was associated with a thinner global p-RNFL by 4.4 μm (P < .001). Reduced p-RNFL was also associated with increased numbers of smokers in the family (β = -3.40, P < .001) and increased quantity of SHS (β = -0.22, P < .001).

Conclusions: Exposure to SHS in children was associated with a thinner p-RNFL. A thinner p-RNFL may increase the risk of irreversible visual impairment in the future. Our results provide evidence to recommend that children avoid exposure to SHS.
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http://dx.doi.org/10.1016/j.ajo.2020.10.016DOI Listing
March 2021

Is Involved in Corneal Stroma Development by Regulating Neural Crest Migration.

Int J Mol Sci 2020 Oct 21;21(20). Epub 2020 Oct 21.

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.

Previously, we identified RAD21 from a peripheral sclerocornea pedigree. Injection of this variant mRNA into embryos disrupted the organization of corneal stroma fibrils. To understand the mechanisms of RAD21-mediated corneal stroma defects, gene expression and chromosome conformation analysis were performed using cells from family members affected by peripheral sclerocornea. Both gene expression and chromosome conformation of cell adhesion genes were affected in cells carrying the heterozygous variant. Since cell migration is essential in early embryonic development and sclerocornea is a congenital disease, we studied neural crest migration during cornea development in embryos. In embryos injected with mutant mRNA, neural crest migration was disrupted, and the number of neural crest-derived periocular mesenchymes decreased significantly in the corneal stroma region. Our data indicate that the RAD21 variant contributes to peripheral sclerocornea by modifying chromosome conformation and gene expression, therefore disturbing neural crest cell migration, which suggests RAD21 plays a key role in corneal stroma development.
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http://dx.doi.org/10.3390/ijms21207807DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7594026PMC
October 2020

Elevated level of uric acid in aqueous humour is associated with posterior subcapsular cataract in human lens.

Clin Exp Ophthalmol 2020 12 19;48(9):1183-1191. Epub 2020 Aug 19.

Department of Ophthalmology, Guangdong Eye Institute, Guangdong Academy of Medical Sciences, Guangdong Provincial People's Hospital, Guangzhou, China.

Importance: Age-related cataract is the leading cause of blindness worldwide. The pathological mechanisms causing this disease remain elusive.

Background: To examine the involvement of uric acid (UA) in the pathogenesis of posterior subcapsular cataract (PSC).

Design: Retrospective study and experimental investigation.

Participants: A total of 180 patients with PSC or non-PSC were included.

Methods: Samples obtained from the patients were used to analyse content of UA and for histochemical examinations. The effects of UA on human lens epithelial cells were also investigated.

Main Outcome Measures: Aqueous humour UA and urate deposits.

Results: The results showed a significant increase of aqueous humour UA in patients with PSC. After adjustment for potential confounders, elevated aqueous humour UA (odds ratio [OR] = 1.45) showed a stronger association with PSC than serum UA (OR = 1.10). Gomori methenamine silver staining revealed in PSC an intense deposit of urates in the lens fibres in equatorial regions, and in subcapsular fibres in posterior regions of the lens. Such staining was not detected in the lens with non-PSC. Treatment with UA-induced senescence and apoptosis in human lens epithelial cells in a dose dependent manner. Our results suggest that the elevated level of UA in aqueous humour causes a deposition of urates in human lens epithelium, which could possibly lead to dysfunction of these cells that generates opacification in PSC.

Conclusions And Relevance: These findings indicate the local action of excessive UA in the pathogenesis of PSC. Control of serum UA level could delay the progression of PSC.
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http://dx.doi.org/10.1111/ceo.13835DOI Listing
December 2020

Epigallocatechin-3-gallate (EGCG) inhibits myofibroblast transformation of human Tenon's fibroblasts.

Exp Eye Res 2020 08 27;197:108119. Epub 2020 Jun 27.

Department of Ophthalmology, Guangdong Eye Institute, Guangdong Provincial People's Hospital and Guangdong Academy of Medical Sciences. Guangzhou, China; The Second School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong, China. Electronic address:

Myofibroblast transformation of human Tenon's fibroblasts severely challenges the outcome of glaucoma filtration surgery. epigallocatechin-3-gallate (EGCG) is considered as a potential reagent to overcome this issue for its anti-fibrosis effect on various human diseases, but it is unclear on the fibrosis of Tenon's fibroblasts. This study was conducted to investigate the effect of EGCG on TGF-β1-induced myofibroblast transformation of human Tenon's fibroblasts. The human Tenon's fibroblasts were incubated in the medium containing 10 ng/mL TGF-β1, and subsequently treated with EGCG or mitomycin C (MMC). The cell proliferation and migration were analyzed. The expression of alpha-smooth muscle actin (α-SMA), type I collagen (Col-I), and p-Smad2/3 were also evaluated. It showed that EGCG and MMC strongly inhibited the elevation in cell number in tissue explants compared to the tissues treated with TGF-β1 alone. Scratch-Wound assay showed that 48 h after TGF-β1 induction, only 10% of the wound width remained. But cells treated with EGCG still showed over 93% wound width. Further, EGCG effectively inhibited TGF-β1-induced expression of α-SMA and Col-I as well as phosphorylation of Smad2/3 in Tenon's fibroblasts. Altogether, we concluded that EGCG suppressed the myofibroblast transformation in Tenon's fibroblasts through inactivating TGF-β1/Smad signaling. These findings demonstrate that EGCG can be considered as one of the possible antifibrotic reagents for preventing postoperative scarring in glaucoma filtration surgery.
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http://dx.doi.org/10.1016/j.exer.2020.108119DOI Listing
August 2020

MicroRNA-19a-PTEN Axis Is Involved in the Developmental Decline of Axon Regenerative Capacity in Retinal Ganglion Cells.

Mol Ther Nucleic Acids 2020 Sep 1;21:251-263. Epub 2020 Jun 1.

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, PRC. Electronic address:

Irreversible blindness from glaucoma and optic neuropathies is attributed to retinal ganglion cells (RGCs) losing the ability to regenerate axons. While several transcription factors and proteins have demonstrated enhancement of axon regeneration after optic nerve injury, mechanisms contributing to the age-related decline in axon regenerative capacity remain elusive. In this study, we show that microRNAs are differentially expressed during RGC development and identify microRNA-19a (miR-19a) as a heterochronic marker; developmental decline of miR-19a relieves suppression of phosphatase and tensin homolog (PTEN), a key regulator of axon regeneration, and serves as a temporal indicator of decreasing axon regenerative capacity. Intravitreal injection of miR-19a promotes axon regeneration after optic nerve crush in adult mice, and it increases axon extension in RGCs isolated from aged human donors. This study uncovers a previously unrecognized involvement of the miR-19a-PTEN axis in RGC axon regeneration, and it demonstrates therapeutic potential of microRNA-mediated restoration of axon regenerative capacity in optic neuropathies.
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http://dx.doi.org/10.1016/j.omtn.2020.05.031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7327411PMC
September 2020

Signaling mechanisms of growth hormone-releasing hormone receptor in LPS-induced acute ocular inflammation.

Proc Natl Acad Sci U S A 2020 03 2;117(11):6067-6074. Epub 2020 Mar 2.

School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China;

Ocular inflammation is a major cause of visual impairment attributed to dysregulation of the immune system. Previously, we have shown that the receptor for growth-hormone-releasing hormone (GHRH-R) affects multiple inflammatory processes. To clarify the pathological roles of GHRH-R in acute ocular inflammation, we investigated the inflammatory cascades mediated by this receptor. In human ciliary epithelial cells, the NF-κB subunit p65 was phosphorylated in response to stimulation with lipopolysaccharide (LPS), resulting in transcriptional up-regulation of GHRH-R. Bioinformatics analysis and coimmunoprecipitation showed that GHRH-R had a direct interaction with JAK2. JAK2, but not JAK1, JAK3, and TYK2, was elevated in ciliary body and iris after treatment with LPS in a rat model of endotoxin-induced uveitis. This elevation augmented the phosphorylation of STAT3 and production of proinflammatory factors, including IL-6, IL-17A, COX2, and iNOS. In explants of iris and ciliary body, the GHRH-R antagonist, MIA-602, suppressed phosphorylation of STAT3 and attenuated expression of downstream proinflammatory factors after LPS treatment. A similar suppression of STAT3 phosphorylation was observed in human ciliary epithelial cells. In vivo studies showed that blocking of the GHRH-R/JAK2/STAT3 axis with the JAK inhibitor Ruxolitinib alleviated partially the LPS-induced acute ocular inflammation by reducing inflammatory cells and protein leakage in the aqueous humor and by repressing expression of STAT3 target genes in rat ciliary body and iris and in human ciliary epithelial cells. Our findings indicate a functional role of the GHRH-R/JAK2/STAT3-signaling axis in acute anterior uveitis and suggest a therapeutic strategy based on treatment with antagonists targeting this signaling pathway.
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http://dx.doi.org/10.1073/pnas.1904532117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7084074PMC
March 2020

Increased Expression of Growth Hormone-Releasing Hormone in Fibrinous Inflammation of Proliferative Diabetic Retinopathy.

Am J Ophthalmol 2020 07 14;215:81-90. Epub 2020 Feb 14.

Department of Ophthalmology, Guangdong Eye Institute, Guangdong Academy of Medical Sciences, Guangdong Provincial People's Hospital, Guangzhou, China. Electronic address:

Purpose: To investigate the involvement of growth hormone-releasing hormone (GHRH) - growth hormone (GH) signaling in pathogenesis of proliferative diabetic retinopathy (PDR).

Design: Experimental laboratory study.

Methods: Vitreous humor, aqueous humor, and serum were obtained from 36 eyes of 36 patients with or without type 2 diabetes from 2017 to 2019. For histologic examination, 6 fibrovascular membranes were excised from eyes with active PDR. Three fibrovascular membranes were excised from nondiabetic patients with proliferative vitreoretinopathy (PVR) as controls.

Results: In PDR, the fibrovascular tissues consisted of a mature region containing fibrocytes, and an immature region populated by abundant polymorphonuclear leukocytes in a fibrinogen meshwork. Clusters of leukocytes were found adhering to the vascular walls. In PVR, no fibrinogen and polymorphonuclear leukocyte was observed in the fibrovascular membranes. The levels of GHRH and GH in PDR were significantly increased (P < .001), with 1.8-fold and 72.8-fold in vitreous humor, and 2-fold and 4.9-fold in aqueous humor, respectively, when compared with corresponding levels in controls. No significant difference was detected for insulin-like growth factor-1. Immunohistochemistry showed intense expression of GHRH and its receptor GHRH-R in polymorphonuclear leukocytes, vascular endothelial cells, and fibrocytes in fibrovascular membranes of PDR. GHRH staining was not detectable in infiltrating cells within the fibrovascular membrane of PVR.

Conclusions: These findings reveal a possible involvement of GHRH/GHRH-R in fibrinous inflammation that might contribute to the formation of fibrovascular membrane in PDR through mediating activities of leukocytes, vascular endothelial cells, and fibrocytes. Targeting GHRH/GHRH-R may be considered as a potential therapeutic approach for the treatment of PDR.
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http://dx.doi.org/10.1016/j.ajo.2020.02.006DOI Listing
July 2020

Pterygium: new insights.

Eye (Lond) 2020 06 6;34(6):1047-1050. Epub 2020 Feb 6.

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong.

Pterygia are common conjunctival degenerations with well-documented risk factors but an unclear pathogenesis. Better understanding of the pathogenesis of pterygium could lead to improved surgical outcomes and decreased postoperative recurrence. Currently, pterygium excision with conjunctival autograft remains the preferred surgical technique to decrease pterygium recurrence. Many adjuvant therapies have been used in pterygium surgery to varying degrees of success. Topical cyclosporine, an immunosuppressive medication, in conjunction with conjunctival autograft was found to be most successful in decreasing pterygium recurrence according to a recent meta-analysis. Other adjuvant therapies such as mitomycin-C (MMC), 5-fluorouracil (5-FU), and beta-irradiation have also been used, though usage of these may cause multiple adverse effects. Recent research indicates that interactions between mouse double minute 2 (MDM2) and p53 could play a role in the occurrence of pterygium. Nutlin, an MDM2 antagonist, was found to have significantly less toxicity in conjunctival cells when compared with MMC on laboratory analysis of pterygium samples.
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http://dx.doi.org/10.1038/s41433-020-0786-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7413326PMC
June 2020

A Cohesin Subunit Variant Identified from a Peripheral Sclerocornea Pedigree.

Dis Markers 2019 12;2019:8781524. Epub 2019 Nov 12.

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong.

Background: Sclerocornea is a rare congenital disorder characterized with the opacification of the cornea. Here, we report a nonconsanguineous Chinese family with multiple peripheral sclerocornea patients spanning across three generations inherited in an autosomal dominant manner.

Methods: This is a retrospective case series of a peripheral sclerocornea pedigree. Comprehensive ophthalmic examinations were conducted and assessed on 14 pedigree members. Whole-exome sequencing was used to identify the genetic alterations in the affected pedigree members. Lymphoblastoid cell lines (LCLs) were established using blood samples from the family members. Functional tests were performed with these cell lines.

Results: Six affected and eight unaffected members of a family with peripheral sclerocornea were examined. All affected individuals showed features of scleralization over the peripheral cornea of both eyes. Mean horizontal and vertical corneal diameter were found significantly decreased in the affected members. Significant differences were also observed on the mean apex pachymetry between affected and unaffected subjects. These ophthalmic parameters did not resemble that of cornea plana. A variant was identified by whole-exome sequencing. Although this variant causes RAD21 R450C substitution at the separase cleavage site, cells from peripheral sclerocornea family members had no mitosis and ploidy defects.

Conclusion: We report a family of peripheral sclerocornea with no association with cornea plana. A variant was found cosegregating with peripheral sclerocornea. Our results suggest that RAD21 functions, other than its cell cycle and chromosome segregation regulations, could underline the pathogenesis of peripheral sclerocornea.
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http://dx.doi.org/10.1155/2019/8781524DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6875196PMC
April 2020

Coding Region Mutation Screening in Optineurin in Chinese Normal-Tension Glaucoma Patients.

Dis Markers 2019 6;2019:5820537. Epub 2019 May 6.

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong.

Purpose: To study the roles of sequence alterations in the optineurin () gene-coding region in normal-tension glaucoma (NTG) among Chinese patients.

Methods: Genomic DNA was extracted from 190 NTG patients and 201 control subjects. The thirteen exons of were amplified by polymerase chain reaction and analyzed by direct sequencing. Detected sequence changes were compared between NTG patients and control subjects.

Results: Seven sequence changes in were identified in both NTG patients and control subjects. Among them, c.464G>A (T34 T), c.509C>T (T49T), c.806G>A (V148V), and c.959T>C (P199P) were synonymous codon changes, whilst c.655T>A (M98K), c.1996G>A (R545Q), and c.1582T>C (I407T) were missense changes. Two previously reported heterozygous mutations, c.458G>A (E50K) in exon 4 and c.691_692insAG in exon 6, were not found in this study. Out of these seven sequence variants, c.464G>A (T34T) was significantly associated with NTG in both the allelic and genotypic association analyses (allelic association: = 0.0001, OR = 2.20, 95% CI: 1.46-3.31; genotypic association: = 0.0001), whereas the association of other variants with NTG did not reach statistical significance ( > 0.05). Variants c.1582 T>C (I407T) and c.806G>A (V148V) were identified in one and two NTG patients, respectively, but not in the control subjects.

Conclusions: This study confirmed the association of the OPTN T34T variant with NTG, suggesting that is a susceptibility gene for NTG in Chinese. Moreover, a variant with amino acid change (I407T) was identified in NTG but not in controls. Further studies are warranted to assess whether this variant is a causative mutation for NTG.
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http://dx.doi.org/10.1155/2019/5820537DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6526575PMC
November 2019

A sclerocornea-associated RAD21 variant induces corneal stroma disorganization.

Exp Eye Res 2019 08 5;185:107687. Epub 2019 Jun 5.

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong; Shantou University/Chinese University of Hong Kong Joint Shantou International Eye Center, Shantou, China.

Sclerocornea is a cornea opacification disorder. Disorganized corneal stroma fibrils are observed in patients' cornea. Previously we identified a RAD21 variant that is associated with a peripheral sclerocornea pedigree. To explore whether this RAD21 variant can induce sclerocornea-related phenotype, and to investigate the possible mechanisms of such phenotype, the orthologous rad21 wild-type and variant mRNAs were injected into Xenopus laevis embryos and the developed eyes were subjected for histological examination. Transmission electron microscopy was applied for corneal stroma organization check. rad21 is highly expressed in the eye region during X. laevis development. Disrupted eye development was observed in the rad21 variant injected embryos. Disorganized corneal stroma and decreased diameters of collagen fibrils were observed in the rad21 variant injected X. laevis eyes. These eye defects can be rescued by overexpression of the wild-type rad21. Histological examination found stroma attracting center, a key structure in X. laevis corneal development, was impaired in rad21 variant injected embryos. Our results suggest a key role of RAD21 during corneal development. Our data indicates the RAD21 variant contributes to peripheral sclerocornea by disturbing collagen fibril organization in the corneal stroma.
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http://dx.doi.org/10.1016/j.exer.2019.06.001DOI Listing
August 2019

Rapamycin Removes Damaged Mitochondria and Protects Human Trabecular Meshwork (TM-1) Cells from Chronic Oxidative Stress.

Mol Neurobiol 2019 Sep 22;56(9):6586-6593. Epub 2019 Mar 22.

Department of Ophthalmology and Visual Sciences, Hong Kong Eye Hospital, The Chinese University of Hong Kong, 147K Argyle Street, Kowloon, Hong Kong.

Glaucoma is a chronic optic neuropathy that could lead to permanent vision loss. Primary open-angle glaucoma (POAG) is the most common type of glaucoma, with elevated intraocular pressure (IOP) as a major risk factor. IOP is mainly regulated by trabecular meshwork (TM), an important component of the conventional aqueous humor (AH) outflow pathway. TM cells are constantly subjected to oxidative stress. Long-term exposure to oxidative stress has been shown to cause elevation of AH outflow resistance, leading to higher IOP. In this study, we induced chronic oxidative stress in human trabecular meshwork (TM-1) cells with 1 μM rotenone and investigated the levels of reactive oxygen species (ROS), autophagy, and mitochondrial functions. Protective effects of rapamycin, an inducer of autophagy, were also investigated. Our data indicated that rotenone significantly increased oxidative stress, but not autophagy, in TM-1 cells. Rapamycin at 10 nM effectively suppressed the rotenone-induced cell apoptosis, as well as the ROS elevation. The protective effects of rapamycin could be associated to the induction of autophagy and removal of damaged mitochondria in TM-1 cells. Our results suggest autophagy has important roles in protecting TM-1 cells from oxidative stress, which could be further developed into a novel treatment to POAG.
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http://dx.doi.org/10.1007/s12035-019-1559-5DOI Listing
September 2019

Growth hormone-releasing hormone receptor mediates cytokine production in ciliary and iris epithelial cells during LPS-induced ocular inflammation.

Exp Eye Res 2019 04 1;181:277-284. Epub 2019 Mar 1.

School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong. Electronic address:

The receptor for growth hormone-releasing hormone (GHRH-R) has been shown to upregulate specifically in the ciliary and iris epithelial cells and infiltrating cells in the aqueous humor in a rat model of acute anterior uveitis. Treatment with GHRHR-R antagonist alleviates significantly these inflammatory responses. Herein we investigated whether the ciliary and iris epithelial cells can respond directly to lipopolysaccharide (LPS) without the influences of circulating leukocytes to produce inflammatory mediators through a GHRH-R mediated mechanism. In explant cultures of rat ciliary body and iris, LPS caused a substantial increase of GHRH-R in 24 h. Immunohistochemistry showed a localization of TLR4, the receptor for LPS, and an elevated expression of IL-6 and IL-1β in ciliary and iris epithelial cells after LPS treatment. LPS also elevated the level of IL-1β, IL-6, and iNOS and increased secretion of IL-1β and IL-6 from the explants. The GHRH-R antagonist, MIA-602, suppressed the elevated expression of IL-1β and IL-6, and reduced the release of IL-6. Such effects were not seen for the GHRHR agonist, MR-409. When co-cultured with leukocytes, expression of GHRH-R in the ocular explants was further enhanced during LPS treatment. Our results demonstrate a direct action of LPS on ciliary and iris epithelial cells to produce pro-inflammatory factors through a GHRH-R mediated mechanism, and suggest a role of these epithelial cells, in addition to the resident antigen presenting cells, in immune surveillance of the eye. Infiltrating leukocytes may enhance these inflammatory responses by regulating GHRH-R in ciliary and iris epithelial cells, in addition to their functions of synthesizing proinflammatory cytokines.
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http://dx.doi.org/10.1016/j.exer.2019.02.021DOI Listing
April 2019

Green tea catechins alleviate autoimmune symptoms and visual impairment in a murine model for human chronic intraocular inflammation by inhibiting Th17-associated pro-inflammatory gene expression.

Sci Rep 2019 02 19;9(1):2301. Epub 2019 Feb 19.

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong.

Autoimmune uveitis is a sight-threatening disease mainly caused by dysregulation of immunity. We investigated the therapeutic effects of green tea extract (GTE) and its major component, epigallocatechin-3-gallate (EGCG), on a murine model of experimental autoimmune uveoretinitis (EAU). Oral administration of GTE, EGCG, dexamethasone, or water, which started 5 days before the induction, was fed every two days to each group. On day 21 post induction, the eyes were examined by confocal scanning laser ophthalmoscopy, optical coherence tomography (OCT), fundus fluorescein angiography (FFA) and electroretinography (ERG) prior to sacrificing the animals for histological assessments and gene expression studies. Retinal-choroidal thicknesses (RCT) and major retinal vessel diameter were measured on OCT sections and FFA images, respectively. Comparing to water-treated EAU animals, GTE attenuated uveitis clinical manifestations, RCT increase (1.100 ± 0.013 times vs 1.005 ± 0.012 times, P < 0.001), retinal vessel dilation (308.9 ± 6.189 units vs 240.8 units, P < 0.001), ERG amplitudes attenuation, histopathological ocular damages, and splenomegaly in EAU mice. The therapeutic effects of GTE were dose dependent and were comparable to dexamethasone. EGCG, a major active constituent of GTE, partially alleviated uveitic phenotypes including recovering visual function. Th-17 associated pro-inflammatory gene [interleukin 1 beta (IL-1β), IL-6, IL-17A, and tumor necrosis factor alpha (TNF-α)] expressions were down regulated by GTE and EGCG treatments, which showed no detectable morphological defects in liver and kidney in non-induced and EAU mice. Our findings suggest that GTE consumption can serve as a potent therapeutic agent as well as a food supplement for developing alternative treatments against autoimmune uveitis.
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http://dx.doi.org/10.1038/s41598-019-38868-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6381204PMC
February 2019

Elevated bone morphogenic protein 4 expression implicated in site-specific adipogenesis in thyroid associated orbitopathy.

Exp Eye Res 2019 04 2;181:185-189. Epub 2019 Feb 2.

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, 4/F, Hong Kong Eye Hospital, 147K Argyle Street, Kowloon, Hong Kong, China; Department of Ophthalmology and Visual Sciences, 1/F, Eye Centre, Prince of Wales Hospital, 30-32 Ngan Shing St, Sha Tin, Hong Kong, China. Electronic address:

Periorbital adipose tissue expansion is a key pathological change in thyroid associated orbitopathy (TAO). Bone morphogenic protein 4 (BMP4) is instrumental in adipogenesis. We compared site-specific BMP4 expression and its effect on adipogenesis using donor-matched adipose tissue-derived stromal cells (ADSC) from TAO patients. In this study, ADSC were generated from periorbital (eyelid, orbital) and subcutaneous (abdominal) adipose tissue. BMP4 expression was characterized by RT-PCR and immunofluorescent staining and compared among ADSC from the three anatomic depots. Effects on adipogenesis after knocking down endogenous BMP4 were quantified by adipogenic markers PPARγ and perilipin. Exogenous BMP4 protein was added after BMP4 knockdown to study the role of BMP4 in adipogenesis. Our results showed that BMP4 staining in periorbital adipose tissue was stronger than those in subcutaneous. BMP4 mRNA expression was higher in eyelid (4.4-2489.4-fold) and orbital (6.9-1811-fold) than that of subcutaneous ADSC, whereas expression fell during induced adipogenesis. After BMP4 knockdown, both adipogenic markers PPARγ (eyelid: 1.7-fold, p = 0.038; orbital: 1.4-fold, p = 0.126) and perilipin (eyelid:1.7-fold, p = 0.001; orbital:2.6-fold, p = 0.066) increased in periorbital ADSC upon induction. These increased expression fell after adding exogenous BMP4 protein. Our findings demonstrated higher BMP4 expression was found in periorbital ADSC and adipose tissue compared to donor-matched subcutaneous counterparts, which fell during adipogenic induction. Knocking down BMP4 expression further enhanced adipogenesis in periorbital ADSC. This effect was reversed by adding exogenous BMP4 protein. We suggested a novel role of BMP4 in modulating site-specific adipogenesis in TAO patients.
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http://dx.doi.org/10.1016/j.exer.2019.01.020DOI Listing
April 2019

Induction of Apoptosis in Pterygium Cells by Antagonists of Growth Hormone-Releasing Hormone Receptors.

Invest Ophthalmol Vis Sci 2018 10;59(12):5060-5066

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.

Purpose: The aim of the study was to investigate the signaling of growth hormone-releasing hormone receptor (GHRH-R) in the pathogenesis of pterygium and determine the apoptotic effect of GHRH-R antagonist on pterygium epithelial cells (PECs).

Methods: Fourteen samples of primary pterygium of grade T3 with size of corneal invasion ≥ 4 mm were obtained for investigation by histology, immunofluorescence, electron microscopy, explant culture, and flow cytometry.

Results: We found that PECs were localized in the basal layer of the epithelium in advancing regions of the head of pterygium. These cells harbored clusters of rough endoplasmic reticulum, ribosomes, and mitochondria, which were consistent with their aggressive proliferation. Immunofluorescence studies and Western blots showed that GHRH-R and the downstream growth hormone receptor (GH-R) were intensively expressed in PECs. Their respective ligands, GHRH and GH, were also elevated in the pterygium tissues as compared to conjunctival cells. Explanted PECs were strongly immunoreactive to GHRH-R and exhibited differentiation and proliferation that led to lump formation. Treatment with GHRH-R antagonist MIA-602 induced apoptosis of PECs in a dose-dependent manner, which was accompanied by a downregulation of ERK1 and upregulation of Caspase 3 expression.

Conclusions: Our results revealed that GHRH-R signaling is involved in survival and proliferation of PECs and suggest a potential therapeutic approach for GHRH-R antagonist in the treatment of pterygium.
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http://dx.doi.org/10.1167/iovs.18-24751DOI Listing
October 2018

Continuous exposure of nicotine and cotinine retards human primary pterygium cell proliferation and migration.

J Cell Biochem 2019 03 27;120(3):4203-4213. Epub 2018 Sep 27.

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong.

Pterygium is a triangular-shaped hyperplastic growth, characterized by conjunctivalization, inflammation, and connective tissue remodeling. Our previous meta-analysis found that cigarette smoking is associated with a reduced risk of pterygium. Yet, the biological effect of cigarette smoke components on pterygium has not been studied. Here we reported the proliferation and migration properties of human primary pterygium cells with continuous exposure to nicotine and cotinine. Human primary pterygium cells predominantly expressed the α5, β1, and γ subunits of the nicotinic acetylcholine receptor. Continuous exposure to the mixture of 0.15 μM nicotine and 2 μM cotinine retarded pterygium cell proliferation by 16.04% (P = 0.009) and hindered their migration by 11.93% ( P = 0.039), without affecting cell apoptosis. SNAIL and α-smooth muscle actin protein expression was significantly downregulated in pterygium cells treated with 0.15 μM nicotine-2 μM cotinine mixture by 1.33- ( P = 0.036) and 1.31-fold ( P = 0.001), respectively. Besides, the 0.15 μM nicotine-2 μM cotinine mixture also reduced matrix metalloproteinase (MMP)-1 and MMP-9 expressions in pterygium cells by 1.56- ( P = 0.043) and 1.27-fold ( P = 0.012), respectively. In summary, this study revealed that continuous exposure of nicotine and cotinine inhibited human primary pterygium cell proliferation and migration in vitro by reducing epithelial-to-mesenchymal transition and MMP protein expression, partially explaining the lower incidence of pterygium in cigarette smokers.
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http://dx.doi.org/10.1002/jcb.27707DOI Listing
March 2019

The Evolving Story of Pterygium.

Cornea 2018 Nov;37 Suppl 1:S55-S57

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.

Pterygium is a fibrovascular subepithelial growth of degenerative tissue over the limbus. It is a common condition worldwide that is especially prevalent in tropical countries within the "pterygium belt." Its exact etiology remains to be elucidated; however, it is strongly associated with exposure to ultraviolet light. The high expression levels of tumor protein p53 (TP53) observed in laboratory studies of pterygium seem to contradict the fast-growing nature of its clinical behavior, and TP53 mutations have been suggested. We demonstrated that mouse double minute 2 (MDM2), a TP53-binding protein, contributes to the inhibition of TP53 activity in human pterygium. Thus, disruption of the MDM2-TP53 interaction should attenuate human pterygium cell growth. For primary pterygium, treatment is relatively straightforward and involves surgical excision. To minimize the risk of recurrence, many adjunctive therapies are adopted, including antimetabolites, such as mitomycin C and 5-fluorouracil, amniotic membrane, different variations on conjunctival and/or limbal conjunctival grafts, and other medications such as anti-vascular endothelial growth factor. In the future, MDM2 antagonists may help further lower the recurrence rates after the treatment of pterygium.
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http://dx.doi.org/10.1097/ICO.0000000000001744DOI Listing
November 2018

Potential Roles of the Retinoblastoma Protein in Regulating Genome Editing.

Front Cell Dev Biol 2018 31;6:81. Epub 2018 Jul 31.

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong.

Genome editing is an important tool for modifying genomic DNA through introducing DNA insertion or deletion at specific locations of a genome. Recently CRISPR/Cas9 has been widely employed to improve the efficiency of genome editing. The Cas9 nuclease creates site-specific double strand breaks (DSBs) at targeted loci in the genome. Subsequently, the DSBs are repaired by two pathways: Homologous Recombination (HR) and Non-Homologous End-Joining (NHEJ). HR has been considered as "error-free" because it repairs DSBs by copying DNA sequences from a homologous DNA template, while NHEJ is "error-prone" as there are base deletions or insertions at the breakage site. Recently, , a gene that is commonly mutated in retinoblastoma, has been reported to affect the repair efficiencies of HR and NHEJ. This review focuses on the roles of in repairing DNA DSBs, which have impacts on the precision and consequences of the genome editing, both at the targeted loci and the overall genome.
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http://dx.doi.org/10.3389/fcell.2018.00081DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6079259PMC
July 2018

p53 inhibition by MDM2 in human pterygium.

Exp Eye Res 2018 10 19;175:142-147. Epub 2018 Jun 19.

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Kowloon, Hong Kong; Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address:

Aims: To confirm that mouse double minute 2 (MDM2) could inhibit p53 activity in human pterygium. And to show the disruption of MDM2-p53 interaction could reactive the functions of p53 in pterygium.

Method: Pterygium and corresponding conjunctiva tissues were collected for establishment of primary cell lines. Expression patterns of MDM2 and p53 were detected by immunofluorescence. Protein localization of p53 and MDM2, and transcriptional activity of p53 in both untreated and MDM2 antagonist (Nutlin) treated pterygium cells were quantified.

Results: In pterygium, p53 was highly expressed in cytoplasm and slightly expressed in the nuclei. MDM2 was localized in the nuclei. A p53 transcriptional regulated target gene, p21, was not expressed in pterygium tissues, suggesting the p53 transcriptional activity was not active in pterygium. After treatment with Nutlin, increased nuclear localization of p53 (4.05%-80.56%) was observed in pterygium cells along with increasing Nutlin dosages (from 0 to 50 μM, p < 0.001). The expression of p21 was increased after Nutlin treatments in pterygium cells (2.49 folds in 20 μM Nutlin treated cells compared to control treated cells, p = 0.012).

Conclusion: We discovered a novel mechanism in pterygium whereby MDM2 suppresses p53 transcriptional activity despite abundant p53 in pterygium. Disruption of MDM2-p53 interaction by Nutlin could be a potential treatment for pterygium.
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http://dx.doi.org/10.1016/j.exer.2018.06.021DOI Listing
October 2018

DNA replication stress and its impact on chromosome segregation and tumorigenesis.

Semin Cancer Biol 2019 04 23;55:61-69. Epub 2018 Apr 23.

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong. Electronic address:

Genome instability and cell cycle dysregulation are commonly associated with cancer. DNA replication stress driven by oncogene activation during tumorigenesis is now well established as a source of genome instability. Replication stress generates DNA damage not only during S phase, but also in the subsequent mitosis, where it impacts adversely on chromosome segregation. Some regions of the genome seem particularly sensitive to replication stress-induced instability; most notably, chromosome fragile sites. In this article, we review some of the important issues that have emerged in recent years concerning DNA replication stress and fragile site expression, as well as how chromosome instability is minimized by a family of ring-shaped protein complexes known as SMC proteins. Understanding how replication stress impacts on S phase and mitosis in cancer should provide opportunities for the development of novel and tumour-specific treatments.
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http://dx.doi.org/10.1016/j.semcancer.2018.04.005DOI Listing
April 2019

Epigenetic Biomarkers in Cancer.

Dis Markers 2018;2018:4987103. Epub 2018 Feb 20.

Institute of Cancer Research, Medical University of Vienna, Vienna, Austria.

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http://dx.doi.org/10.1155/2018/4987103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5838454PMC
October 2018

Depot-specific characteristics of adipose tissue-derived stromal cells in thyroid-associated orbitopathy.

Br J Ophthalmol 2018 08 17;102(8):1173-1178. Epub 2018 Apr 17.

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China

Background: Thyroid-associated orbitopathy (TAO) causes inflammatory fibroproliferation of periocular connective tissues. We compared adipose tissue-derived stem/stromal cells (ADSCs) from three adipose depots of each patient with TAO on mesenchymal, myofibrogenic, adipogenic properties and associated hyaluronan (HA) synthesis.

Methods: ADSCs were generated from periocular (eyelid, orbital) and subcutaneous (abdominal) adipose tissues of three patients with TAO. Mesenchymal markers were characterised by reverse transcription-PCR and immunofluorescent staining. A 3-week adipogenic induction was evaluated by Nile red staining and quantitative PCR (qPCR) of peroxisome proliferator-activated receptor (PPARγ), adiponectin and hyaluronan synthase (HAS)-2. A 7-day myofibrogenic induction was assayed by immunofluorescent staining and qPCR of α-smooth muscle actin (α-SMA).

Results: ADSCs from all depots expressed similar levels of mesenchymal markers CD44, CD90 and CD105 (p=0.288, p=0.43 and p=0.837, respectively). After adipogenic induction, intracellular lipid increased for more than 32% and PPARγ mRNA showed more than twofold increase from all three depots. However, adiponectin and HAS-2 mRNA levels were significantly higher in the eyelid and orbital ADSCs than those from the subcutaneous ADSCs after induction (2.4×10, 3.9×10 folds vs below detection limit; 63.3-fold, 26.1-fold, vs 33% reduction, respectively; all p=0.002). Significantly more myofibroblasts and higher mRNA level of α-SMA were obtained from the orbital and eyelid compared with the subcutaneous ADSCs during myofibrogenic induction (80.2%, 70.6% vs 29.3%; 30.2-fold, 24.2-fold vs 1.7-fold, respectively; all p=0.002).

Conclusion: ADSCs from different adipose depots of the same donors exhibited similar mesenchymal phenotypes but differed significantly in adipogenic, myofibrogenic potentials and associated HA synthesis. These depot-specific characteristics of ADSCs may contribute to site-specific adipose tissue involvement in TAO.
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http://dx.doi.org/10.1136/bjophthalmol-2017-311339DOI Listing
August 2018

Cellular Proliferation and Migration of Human Pterygium Cells: Mitomycin Versus Small-Molecule Inhibitors.

Cornea 2018 Jun;37(6):760-766

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Kowloon, Hong Kong.

Purpose: Nutlin is a drug that has been reported to activate p53 in various cell lines. We aim to study the effects of Nutlin in pterygium and compare the effects of Nutlin and mitomycin C (MMC) in pterygium cell lines.

Methods: Pterygium samples (n = 3) were collected during surgical excision. Normal conjunctival tissues (n = 3) were collected from another quadrant of the same eye. Cell lines were established, and cells from passages 2 to 5 were used. Pterygium and conjunctival cells were treated with different doses of Nutlin and MMC. Cell proliferation and cell migration were measured.

Results: Cell proliferation was reduced by 39-fold after treatment with 50 μM Nutlin. Cell migration was inhibited with increasing dosages of Nutlin (95% and 28% after treating with 2 and 50 μM Nutlin, respectively). Compared with MMC, Nutlin induced more pterygium cell death and less conjunctival cell death at low doses. At 50% lethal dose for pterygium cells, 95% of conjunctival cells survived after Nutlin treatment, whereas only 63% of conjunctival cells survived after MMC treatment. p21 expression was not detectable in MMC-treated pterygium cells but was detectable after Nutlin treatment.

Conclusions: In our study, MMC induced cell death in pterygium and conjunctival cell lines, whereas Nutlin had a targeted impact on pterygium cells. Our results implied that MMC inhibited both pterygium cell proliferation and migration through an apoptosis-independent pathway.
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http://dx.doi.org/10.1097/ICO.0000000000001569DOI Listing
June 2018

Histological and microRNA Signatures of Corneal Epithelium in Keratoconus.

J Refract Surg 2018 Mar;34(3):201-211

Purpose: To illustrate the histopathology of keratoconic corneal epithelia and its micro-ribonucleic acid (miRNA) regulation.

Methods: Corneal epithelia were collected from 27 patients with keratoconus and 26 normal patients after surgery or by impression cytology. The miRNA profile was determined using miRNA microarray. The biological roles of miRNA target genes were delineated by gene ontology and pathway analyses. The expressions of significant miRNAs were validated using TaqMan polymerase chain reaction (PCR), whereas protein localization and expression of the miRNA target genes were examined by immunofluorescence and immunoblotting analyses.

Results: Histological assessment showed that corneal epithelia in patients with keratoconus were thinner with loosely packed cells compared to normal patients. Microarray analysis revealed that 12 miRNAs were significantly downregulated in keratoconic corneal epithelia. Gene ontology analysis demonstrated that the predicted miRNA target genes participated in cell junction, cell division, and motor activity, whereas pathway analysis highlighted the involvement of syndecan-mediated signaling pathway. TaqMan PCR validated the altered expression of six miRNAs in corneal epithelia from surgery (hsa-miR-151a-3p, hsa-miR-138-5p, hsa-miR-146b-5p, hsa-miR-194-5p, hsa-miR-28-5p, and hsa-miR-181a-2-3p) and four miRNAs in squamous corneal epithelial samples collected from impression cytology (hsa-miR-151a-3p, hsa-miR-195-5p, hsa-miR-185-5p, and hsa-miR-194-5p). In addition, higher S100A2 expression was found in the epithelial basal cell layer of keratoconic corneal epithelia.

Conclusions: The miRNA and histological analyses in this study demonstrated structural and biological changes in keratoconic corneal epithelia, broadening the understanding of keratoconus pathology. In addition, impression cytology is useful to collect corneal epithelial tissues for gene expression analysis. [J Refract Surg. 2018;34(3):201-211.].
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http://dx.doi.org/10.3928/1081597X-20171215-02DOI Listing
March 2018

Green tea extract attenuates LPS-induced retinal inflammation in rats.

Sci Rep 2018 01 11;8(1):429. Epub 2018 Jan 11.

School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China.

Inflammation is in a wide spectrum of retinal diseases, causing irreversible blindness and visual impairment. We have previously demonstrated that Green Tea Extract (GTE) is a potent anti-inflammatory agent for anterior uveitis. Here we investigated the anti-inflammatory effect of GTE on lipopolysaccharides (LPS)-induced retinal inflammation in rats and explored the underlying mechanism. Adult rats were injected with LPS and GTE was administered intra-gastrically at 2, 8, 26 and 32 hours post-injection. Staining of whole-mount retina showed that the number of activated microglia cells was significantly increased at 48 hours post-injection, which was suppressed after GTE treatment in a dose-dependent manner. Activation of astrocytes and Müller glia in the retina was also suppressed after GTE treatment. Meanwhile, GTE reduced the expression of pro-inflammatory cytokines including IL-1β, TNF-α and IL-6 in retina and vitreous humor. These anti-inflammatory effects were associated with a reduced phosphorylation of STAT3 and NF-κB in the retina. Furthermore, the surface receptor of EGCG, 67LR, was localized on the neurons and glia in the retina. These findings demonstrate that GTE is an effective agent in suppressing LPS-induced retinal inflammation, probably through its potent anti-oxidative property and a receptor-mediated action on transcription factors that regulate production of pro-inflammatory cytokines.
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http://dx.doi.org/10.1038/s41598-017-18888-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5765135PMC
January 2018

DNA Methylation as a Noninvasive Epigenetic Biomarker for the Detection of Cancer.

Dis Markers 2017 5;2017:3726595. Epub 2017 Sep 5.

Asbestos Disease Research Institute, Sydney Medical School, University of Sydney, Rhodes, NSW, Australia.

In light of the high incidence and mortality rates of cancer, early and accurate diagnosis is an important priority for assigning optimal treatment for each individual with suspected illness. Biomarkers are crucial in the screening of patients with a high risk of developing cancer, diagnosing patients with suspicious tumours at the earliest possible stage, establishing an accurate prognosis, and predicting and monitoring the response to specific therapies. Epigenetic alterations are innovative biomarkers for cancer, due to their stability, frequency, and noninvasive accessibility in bodily fluids. Epigenetic modifications are also reversible and potentially useful as therapeutic targets. Despite this, there is still a lack of accurate biomarkers for the conclusive diagnosis of most cancer types; thus, there is a strong need for continued investigation to expand this area of research. In this review, we summarise current knowledge on methylated DNA and its implications in cancer to explore its potential as an epigenetic biomarker to be translated for clinical application. We propose that the identification of biomarkers with higher accuracy and more effective detection methods will enable improved clinical management of patients and the intervention at early-stage disease.
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http://dx.doi.org/10.1155/2017/3726595DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5605861PMC
June 2018