UVB-mediated down-regulation of proteasome in cultured human primary pterygium fibroblasts

Conjunctival Autograft versus Combined Amniotic Membrane and Mini-Simple Limbal Epithelial Transplant for Primary Pterygium Excision

Purpose

To compare outcomes of conjunctival autograft (CAG) and combined amniotic membrane with mini-simple limbal epithelial transplant (mini-SLET) after primary pterygium excision.

Methods

All consenting adults with primary pterygium were included in this study. After pterygium excision, patients were randomized to receive either CAG or mini-SLET and both grafts were held in place with fibrin glue. The patients were followed-up at days 1, 3, 7, 14, and 30 and subsequently at the third, sixth, and ninth months. The recurrence rate was considered as the primary outcome measure whereas the operating time, postoperative symptoms, and surgical complications were considered the secondary outcome measures.

Results

The study comprised of 264 eyes of 264 patients, of which 233 (88%) completed the nine months of follow-up. Of these, 118 (51%) received CAG and 115 (49%) received mini-SLET. The groups were comparable at baseline. Recurrence of pterygium was seen in two (1.6%) eyes in the CAG group and three (2.6%) eyes in the mini-SLET group (P = 0.68). Operative time for mini-SLET (20.33 ± 1.28 min) was significantly higher than that for CAG (12.01 ± 1.26 min) (P < 0.001). Graft displacement was observed in one case in group II (P = 0.999). The Lim Bon Siong (foreign body sensation, lacrimation, pain, and irritation) score in the CAG group was statistically significant for all four symptoms at days 1 and 3; however, at day 7, foreign body sensation, pain, and irritation scores were significantly higher for the CAG group.

Conclusion

In this study, the overall recurrence rate was very low and comparable between mini-SLET and the established technique of CAG after performing the primary pterygium excision. Despite a longer surgical time, mini-SLET appears to be a viable option for the management of primary pterygium.

Aβ monomers protect lens epithelial cells against oxidative stress by upregulating CDC25B

Our previous studies showed high β-amyloid (Aβ) expression levels in the nuclei of the lens epithelial cells (LECs) of healthy subjects and revealed that Aβ monomers could protect LECs from oxidative damage. Here, we further explored the mechanism by which Aβ monomers act as transcription factors to regulate the oxidative stress of LECs through high-throughput studies. First, we compared the Aβ-binding sites in the lens epithelia (LE) of age-related cataract patients with those in the LE of healthy donors via chromatin immunoprecipitation-sequencing (ChIP-seq), and we identified comparable numbers (1648 and 1445, respectively) of Aβ peaks. Then, the KEGG tool was used for gene function enrichment analysis of these genes, which were more highly enriched in healthy LE. Combining the literature review with these KEGG analysis results, in the current study, we chose four target genes related to oxidative stress, namely, CDC25B, SOS2, CTNNA1 and Cox6a1. Then, ChIP-PCR assays, dual-luciferase reporter assays, real-time PCR and Western blotting were performed to validate the regulatory effects of Aβ on these targets. Our data suggested that Aβ monomers could upregulate the mRNA and protein expression levels of CDC25B in LECs. We also confirmed that Aβ monomers could activate the Akt/Nrf2 pathway in a CDC25B-dependent manner by knockdown experiments in cultured LECs. Furthermore, we performed functional verification of the CDC25B-mediated protective effects of Aβ monomers against oxidative stress. We observed that Aβ monomers significantly improved the antioxidant capacity (the GSH level, SOD activity and total antioxidant capacity) and decreased the oxidative stress (the ROS and MDA levels) of LECs, while CDC25B knockdown decreased the antioxidant effects of Aβ, disrupting redox homeostasis. Therefore, we propose that Aβ monomers activate the Akt/Nrf2 pathway by upregulating CDC25B expression, increase various downstream antioxidant enzyme levels, maintain peroxidation-antioxidant homeostasis in LECs, and prevent the cell damage caused by oxidative stress.

Potential Protective and Therapeutic Roles of the Nrf2 Pathway in Ocular Diseases: An Update

Nuclear factor- (erythroid-derived 2-) like 2 (Nrf2) is a regulator of many processes of life, and it plays an important role in antioxidant, anti-inflammatory, and antifibrotic responses and in cancer. This review is focused on the potential mechanism of Nrf2 in the occurrence and development of ocular diseases. Also, several Nrf2 inducers, including noncoding RNAs and exogenous compounds, which control the expression of Nrf2 through different pathways, are discussed in ocular disease models and ocular cells, protecting them from dysfunctional changes. Therefore, Nrf2 might be a potential target of protecting ocular cells from various stresses and preventing ocular diseases.

A novel role for Livin in the response to ultraviolet B radiation and pterygium development

A pterygium is an inflammatory, invasive and proliferative lesion on the ocular surface, which can decrease visual acuity, damage the ocular surface and affect the appearance of the eye. However, the underlying molecular mechanisms of the pathogenesis remain unclear. In the present study, the role of apoptosis-associated protein Livin in the occurrence and development of pterygium was investigated. Primary samples from quiescent or advanced clinical stages of pterygium and normal human conjunctival tissues were used to assess mRNA and protein expression levels of Livin using reverse transcription-quantitative PCR and immunohistochemistry, respectively. Livin was knocked down in pterygium epithelial cells (PECs) using small interfering RNA (siRNA), to investigate the role of Livin in PEC viability, migration, invasion ability and apoptosis. The cell viability, invasion ability and apoptosis of PECs following ultraviolet B (UVB) radiation alone or in combination with Livin silencing were also analyzed. Expression levels of Livin increased in the pterygium tissues compared with those in the normal conjunctiva at both the mRNA and protein levels. Livin expression levels in advanced pterygium were significantly higher compared with those in quiescent pterygium samples. Knockdown of Livin expression levels significantly reduced cell migration, invasion ability and cell viability, and induced apoptosis of PECs. Inhibition of Livin expression in PECs increased the expression levels of caspase-7, caspase-3 and E-cadherin, whereas expression levels of Snail were downregulated. Cell viability and invasion ability in PECs was enhanced following UVB radiation and Livin expression upregulated. UVB irradiation induced cell invasion ability of PECs and this was attenuated by Livin-silencing. Transfection with Livin siRNA also partially recovered the apoptosis rate of PECs, which was reduced by UVB irradiation. In conclusion, Livin was upregulated in pterygium, and UVB radiation functions in the development of pterygium by inducing Livin expression.

Modification of Collagen Derivatives with Water-Soluble Polymers for the Development of Cross-Linked Hydrogels for Controlled Release

Novel cross-linked hydrogels were synthesized as potential materials for the development of smart biofertilizers. For this purpose, hydrogels were prepared using collagen hydrolysate recovered from tannery waste. The water-soluble polymer poly(sodium 4-styrenesulfonate-co-glycidyl methacrylate) (P(SSNa-co-GMAx)) was among others used for the cross-linking reaction that combined hydrophilic nature with epoxide groups. The synthetic procedure was thoroughly investigated in order to ensure high percentage of epoxide groups in combination with water-soluble behavior. The copolymer did not show cytotoxicity against normal lung, skin fibroblasts, or nasal polyps fibroblasts. Through the present work, we also present the ability to control the properties of cross-linked hydrogels by altering copolymer's composition and cross-linking parameters (curing temperature and time). Hydrogels were then studied in terms of water-uptake capacity for a period up to six days. The techniques Proton Nuclear Magnetic Resonance (1H NMR), Thermogravimetric Analysis (TGA), Size Exclusion Chromatography (SEC), and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) were applied for the characterization of the synthesized copolymers and the cross-linked hydrogels. Three samples of biofertilizers based on collagen hydrolysate functionalized with P(SSNa-co-GMAx) and starch and having nutrients encapsulated (N, P, K) were prepared and characterized by physical-chemical analysis and Energy Dispersive X-ray analysis-Scanning Electron Microscope (EDAX-SEM) in terms of microstructure. Preliminary tests for application as fertilizers were performed including the release degree of oxidable organic compounds.

Clinical Aspects of Pterygium in the Presence of Cataract

Two of the most common UV-induced eye affections are pterygium and cataract. They are both defined as progressive diseases that impair patients’ vision and share some common elements in their evolution process. The purpose of this study was to determine whether the presence of cataract influences the clinical signs and symptoms of patients with pterygium. Therefore, we have analyzed 84 patients with pterygium, among which 23 also presented cataract, as an overall study lot, as well as divided by age decades. We have determined that almost all patients with both pterygium and cataract declared extensive UV exposure in antecedents and have also reported a blurred vision. We found no correlation between the presence of cataract and the size of pterygium lesions, or symptoms like foreign body sensation, tearing or symblepharon.