Lens cell targetting for gene therapy of prevention of posterior capsule opacification

Oxidative Stress and Cataract Formation: Evaluating the Efficacy of Antioxidant Therapies

This comprehensive review investigates the pivotal role of reactive oxygen species (ROS) in cataract formation and evaluates the potential of antioxidant therapies in mitigating this ocular condition. By elucidating the mechanisms of oxidative stress, the article examines how ROS contribute to the deterioration of lens proteins and lipids, leading to the characteristic aggregation, cross-linking, and light scattering observed in cataracts. The review provides a thorough assessment of various antioxidant strategies aimed at preventing and managing cataracts, such as dietary antioxidants (i.e., vitamins C and E, lutein, and zeaxanthin), as well as pharmacological agents with antioxidative properties. Furthermore, the article explores innovative therapeutic approaches, including gene therapy and nanotechnology-based delivery systems, designed to bolster antioxidant defenses in ocular tissues. Concluding with a critical analysis of current research, the review offers evidence-based recommendations for optimizing antioxidant therapies. The current literature on the use of antioxidant therapies to prevent cataract formation is sparse. There is a lack of evidence-based conclusions; further clinical studies are needed to endorse the use of antioxidant strategies in patients to prevent cataractogenesis. However, personalized treatment plans considering individual patient factors and disease stages can be applied. This article serves as a valuable resource, providing insights into the potential of antioxidants to alleviate the burden of cataracts.

FILIP1L-mediated cell apoptosis, epithelial-mesenchymal transition and extracellular matrix synthesis aggravate posterior capsular opacification

AIMS

The epithelial-mesenchymal transition (EMT), extracellular matrix (ECM) synthesis and cell migration of residual lens cells constitute the canonical mechanisms of posterior capsular opacification (PCO). Recently, myofibroblast cell apoptosis is also observed in the rabbit PCO model. However, whether cell apoptosis is a key factor affecting PCO and regulates EMT/ECM synthesis/cell migration remains obscure.

MAIN METHODS

Flow cytometry was utilized to assess cell cycle and apoptosis. EMT marker α-smooth muscle actin (α-SMA), ECM markers fibronectin (Fn), type 1 collagen (COL-1) and apoptosis-associated proteins in the presence or absence of EMT/ECM inhibitor (LY2109761), apoptosis inhibitor (ZVAD) or apoptosis activator (BTSA1) were detected by Western blotting. Downstream effector genes in apoptosis-induced lens epithelial cell lines (LECs) were analyzed by RNA-seq. Gene silencing and overexpression in LECs were performed to validate the role of effector genes. We measured cell migration capability using Wound healing and Transwell assays.

KEY FINDINGS

We found that TGF-β2 induced cell apoptosis. ZVAD inhibited α-SMA expression in the ex vivo capsule model and decreased the expression of both EMT and ECM markers in TGF-β2-treated LECs. RNA-seq revealed that FILIP1L was significantly decreased in apoptosis-activated cells. We further validated that the knockdown of FILIP1L could enhance EMT and ECM synthesis and promote cell migration and that FILIP1L overexpression could reverse these effects. Apoptosis might contribute to TGF-β2-induced EMT and ECM synthesis during PCO, and these contributions are mediated by FILIP1L.

SIGNIFICANCE

Our findings uncover the role of apoptosis in PCO development and provide new drug targets.

Role of the HSP70 Co-Chaperone SIL1 in Health and Disease

Cell surface and secreted proteins provide essential functions for multicellular life. They enter the endoplasmic reticulum (ER) lumen co-translationally, where they mature and fold into their complex three-dimensional structures. The ER is populated with a host of molecular chaperones, associated co-factors, and enzymes that assist and stabilize folded states. Together, they ensure that nascent proteins mature properly or, if this process fails, target them for degradation. BiP, the ER HSP70 chaperone, interacts with unfolded client proteins in a nucleotide-dependent manner, which is tightly regulated by eight DnaJ-type proteins and two nucleotide exchange factors (NEFs), SIL1 and GRP170. Loss of SIL1′s function is the leading cause of Marinesco-Sjögren syndrome (MSS), an autosomal recessive, multisystem disorder. The development of animal models has provided insights into SIL1′s functions and MSS-associated pathologies. This review provides an in-depth update on the current understanding of the molecular mechanisms underlying SIL1′s NEF activity and its role in maintaining ER homeostasis and normal physiology. A precise understanding of the underlying molecular mechanisms associated with the loss of SIL1 may allow for the development of new pharmacological approaches to treat MSS.

Research Progress of Drug Prophylaxis for Lens Capsule Opacification after Cataract Surgery

Phacoemulsification combined with intraocular lens (IOL) implantation is the international standard operation procedure for cataract and has been generalized worldwide. However, lens capsule opacification, one of the common complications after cataract surgery, impacts the recovery of patients' visual function to a large extent. Lens capsule opacification has two types, anterior capsule opacification (ACO) and posterior capsule opacification (PCO), according to the location. There is not an accepted approach to treat ACO. Nd : YAG laser capsulotomy, the common treatment of PCO, can effectively improve the vision, but may cause a series of complications and is inappropriate for children who are too young to cooperate with this treatment. It is generally known that the responses of lens epithelial cells (LECs) after cataract surgery, including cell proliferation, migration, and epithelial-mesenchymal transition (EMT), play a key role in the pathogenesis of lens capsule opacification. Scholars found that substantial drugs can reduce the occurrence of lens capsule opacification by inhibiting, clearing, or killing LECs, and made great efforts as well as innovations on the exploration of drug species or modes of administration. This article is a systematic interpretation and elaboration about how to prevent lens capsule opacification after cataract surgery via different drugs.

Lens epithelial cells-induced pluripotent stem cells as a model to study epithelial-mesenchymal transition during posterior capsular opacification

The overall goal was to generate an epithelial-mesenchymal transition (EMT) model using lens epithelial cells-induced pluripotent stem cells to elucidate EMT-regulatory factors during posterior capsular opacification (PCO). For this purpose, the mouse lens epithelial cells-derived mesenchymal cells were reprogrammed to induced pluripotent stem cells (iPSC) and differentiated to lens epithelial cells to be used to determine regulatory factors during EMT. Lens epithelial cells from one-month-old C57BL/6 mice were transitioned to mesenchymal cells in culture, and were reprogrammed to iPSC by delivering reprogramming factors in a single polycistronic lentiviral vector (co-expressing four transcription factors, Oct 4, Sox2, Klf4, and Myc). iPSC were differentiated to epithelial cells by a three-step process using noggin, basic fibroblast growth factor (bFGF), bone morphogenetic protein 4 (BMP4) and Wnt-3. At various time points, the cells/clones were immunocytochemically analyzed for epithelial cell markers (Connexin-43 and E-cadherin), mesenchymal cell markers (Alpha-smooth muscle actin), stem cell markers (Sox1, Oct4, SSEA4 and Tra60) and lens-specific epithelial cell markers (αA- and βA3/A1-crystallins).

By increasing the number of genetic transductions, the time needed for generating iPSC from lens mesenchymal cells was reduced, successfully reprogrammed epithelial/mesenchymal cells into iPSC, and retransformed iPSC into lens epithelial cells by the growth factors’ treatment. The epithelial cells could serve as a model system to elucidate regulatory factors involved during EMT to therapeutically stop it.

•

By increasing the number of genetic transductions, reduced the time needed for generating iPSC from lens mesenchymal cells.

•

We successfully reprogrammed iPSC, and also differentiated iPSC into lens epithelial cells by the growth factors.

•

Our model could elucidate regulatory factors involved in epithelial mesenchymal transition to therapeutically stop it.

Effect of an MG132-Sustained Drug Delivery Capsular Ring on the Inhibition of Posterior Capsule Opacification in a Rabbit Model

PURPOSE

To design an MG132-sustained drug delivery capsular ring (SDDCR) and investigate its effect on the inhibition of posterior capsule opacification (PCO) in a rabbit model.

METHODS

The SDDCRs were prepared by forming a slice of film made by the mixture of poly lactic-co-glycolic acid (PLGA) and MG132 on the surface of capsular tension rings (CTRs). The drug-loading capacity, entrapment efficiency, and in vitro release of the drug-containing film were detected. Eighteen New Zealand white rabbits were operated with phacoemulsification and MG132-SDDCRs/PLGA-CTRs/CTRs implantation in the single eye. The images of the anterior segments were acquired at certain days, and the epithelial-mesenchymal transition (EMT) markers were detected by western blot and immunofluorescence.

RESULTS

The drug-loading capacity and entrapment efficiency of MG132-SDDCRs were 1.15% ± 0.04% and 66.16% ± 0.027%, respectively, and the drug released well within a month. The PCO degree of the MG132-SDDCR group was significantly lower than the other groups. The expression of alpha-smooth muscle actin, fibronectin, vimentin, and collagen-I was lower, and the expression of E-cadherin (E-cad) was higher in the MG132-SDDCR group than the other groups.

CONCLUSIONS

MG132-SDDCRs could be established successfully. The PCO process was prevented, and the expression of EMT markers was inhibited by the implantation of MG132-SDDCRs, indicating that this could be a potential treatment against PCO.

Development of viral vectors with optimal transgene expression for ocular gene therapies

Striving for ideal viral constructs by modifying its structure, including promoters, would make the viral gene therapy more promising. Further assessment of the promoters and their expression profiles such as those shown in Table 1 and new designs of hybrid promoters may achieve optimal expression features for ocular gene therapies.