NADPH and NAC synergistically inhibits chronic ocular hypertension-induced neurodegeneration and neuroinflammation through regulating p38/MAPK pathway and peroxidation.

Glaucoma, the leading cause of irreversible blindness worldwide, is characterized by neurodegeneration and neuroinflammation with retinal NAD/NADP and GSH decline. Nicotinamide adenine dinucleotide (NAD)/NAD phosphate (NADP) and glutathione (GSH) are two redox reducers in neuronal and glial metabolism. However, therapeutic strategies targeting NAD/NADP or GSH do not exert ideal effects, and the underlying mechanisms are still poorly understood. We assessed morphological changes in retinal ganglion cells (RGCs), the affected neurons in glaucoma, and Müller cells, the major glial cells in the retina, as well as the levels of phosphorylated p38 (p-p38) and Caspase-3 in glaucoma patients. We constructed a modified chronic ocular hypertensive rat model and an oxygen-glucose deprivation (OGD) cell model. After applying NADPH and N-acetylcysteine (NAC), a precursor to cysteine, the rate-limiting substrate in GSH biosynthesis, to cells, apoptosis, axonal damage and peroxidation were reduced in the RGCs of the NAC group and p-p38 levels were decreased in the RGCs of the NADPH group, while in stimulated Müller cells cultured individually or cocultured with RGCs, gliosis and p38/MAPK, rather than JNK/MAPK, activation were inhibited. The results were more synergistic in the rat model, where either NADPH or NAC showed crossover effects on inhibiting peroxidation and p38/MAPK pathway activation. Moreover, the combination of NADPH and NAC ameliorated RGC electrophysiological function and prevented Müller cell gliosis to the greatest extent. These data illustrated conjoined mechanisms in glaucomatous RGC injury and Müller cell gliosis and suggested that NADPH and NAC collaborate as a neuroprotective and anti-inflammatory combination treatment for glaucoma and other underlying human neurodegenerative diseases.

Development and material characteristics of glaucoma surgical implants.

Background: Glaucoma is the leading cause of irreversible blindness worldwide. The reduction of intraocular pressure has proved to be the only factor which can be modified in the treatment, and surgical management is one of the important methods for the treatment of glaucoma patients. Main text: In order to increase aqueous humor outflow and further reduce intraocular pressure, various drainage implants have been designed and applied in clinical practice. From initial Molteno, Baerveldt and Ahmed glaucoma implants to the Ahmed ClearPath device, Paul glaucoma implant, EX-PRESS and the eyeWatch implant, to iStent, Hydrus, XEN, PreserFlo, Cypass, SOLX Gold Shunt, etc., glaucoma surgical implants are currently undergoing a massive transformation on their structures and performances. Multitudinous materials have been used to produce these implants, from original silicone and porous polyethylene, to gelatin, stainless steel, SIBS, titanium, nitinol and even 24-carat gold. Moreover, the material geometry, size, rigidity, biocompatibility and mechanism (valved versus nonvalved) among these implants are markedly different. In this review, we discussed the development and material characteristics of both conventional glaucoma drainage devices and more recent implants, such as the eyeWatch and the new minimally invasive glaucoma surgery (MIGS) devices. Conclusions: Although different in design and materials, these delicate glaucoma surgical implants have widely expanded the glaucoma surgical methods, and improved the success rate and safety of glaucoma surgery significantly. However, all of these glaucoma surgical implants have various limitations and should be used for different glaucoma patients at different conditions.

Keratin8 Deficiency Aggravates Retinal Ganglion Cell Damage Under Acute Ocular Hypertension.

Purpose: Keratin 8/18 (KRT8/18), paired members of the intermediate filament family, have shown vital functions in regulating physiological activities more than supporting the mechanic strength for cells and organelles. However, the KRT8/18 presence in retinal ganglion cells (RGCs) and functions on neuroprotection in a mouse model of acute ocular hypertension (AOH) are unknown and worthy of exploration. Methods: We identified the existence of KRT8/18 in normal human and mouse retinas and primary RGCs. KRT8/18 levels were detected after AOH modeling. The adeno-associated virus (AAV) system was intravitreally used for selective KRT8 knockdown in RGCs. The histological changes, the loss and dysfunction of RGCs, and the gliosis in retinas were detected. The markers of cell apoptosis and MAPK pathways were investigated. Results: KRT8/18 existed in all retinal layers and was highly expressed in RGCs, and they increased after AOH induction. The KRT8 knockdown in RGCs caused no histopathological changes and RGC loss in retinas without AOH modeling. However, after the KRT8 deficiency, AOH significantly promoted the loss of whole retina and inner retina thickness, the reduction, apoptosis, and dysfunction of RGCs, and the glial activation. Besides, downregulated Bcl-2 and upregulated cleaved-Caspase 3 were found in the AOH retinas with KRT8 knockdown, which may be caused by the increased phosphorylation level of MAPK pathways (JNK, p38, and ERK). Conclusions: The KRT8 deficiency promoted RGC apoptosis and neurodegeneration by abnormal activation of MAPK pathways in AOH retinas. Targeting KRT8 may serve as a novel treatment for saving RCGs from glaucomatous injuries.

Inhibition of cGAS-STING pathway alleviates neuroinflammation-induced retinal ganglion cell death after ischemia/reperfusion injury.

Acute glaucoma is a vision-threatening disease characterized by a sudden elevation in intraocular pressure (IOP), followed by retinal ganglion cell (RGC) death. Cytosolic double-stranded DNA (dsDNA)-a damage-associated molecular pattern (DAMP) that triggers inflammation and immune responses-has been implicated in the pathogenesis of IOP-induced RGC death, but the underlying mechanism is not entirely clear. In this study, we investigated the effect of the inflammatory cascade on dsDNA recognition and examined the neuroprotective effect of the cyclic GMP-AMP (cGAMP) synthase (cGAS) antagonist A151 on a retinal ischemia/reperfusion (RIR) mouse model. Our findings reveal a novel mechanism of microglia-induced neuroinflammation-mediated RGC death associated with glaucomatous vision loss. We found that RIR injury facilitated the release of dsDNA, which initiated inflammatory responses by activating cGAS-stimulator of interferon genes (STING) pathway. Correspondingly, elevated expressions of cGAS and STING were found in retinal samples from human glaucoma donors. Furthermore, we found that deletion or inhibition of cGAS or STING in microglia transfected with poly(dA:dT) specifically decreased microglia activation and inflammation response. We also observed that A151 treatment promoted poly(dA:dT)--stimulated changes in polarization from the M1 to the M2 phenotype in microglia. Subsequently, A151 administered to mice effectively inhibited the cGAS-STING pathway, absent in melanoma 2 (AIM2) inflammasome and pyroptosis-related molecules. Furthermore, A151 administration significantly reduced neuroinflammation, ameliorated RGC death and RGC-related reductions in visual function. These findings provide a unique perspective on glaucomatous neuropathogenesis and suggest cGAS as an underlying target of retinal inflammation to provide a potential therapeutic for acute glaucoma.

Thioredoxin-1 regulates the autophagy induced by oxidative stress through LC3-II in human lens epithelial cells.

Oxidative stress plays a major role in age-related cataract development. The cellular antioxidant protein thioredoxin-1 (Trx-1) and its negative regulator, thioredoxin binding protein-2 (TBP-2), are pivotal in the cellular redox balance during oxidative stress. The aim of this study is to investigate the effect of Trx-1 and TBP-2 on LC3 I/LC3 II in oxidative stress-induced autophagy in human lens epithelial cells (LECs). In our study, LECs were treated with 50 µM H2 O2 for different durations, and the expression of Trx-1 and TBP-2 were measured by RT-PCR and Western blot. Trx-1 activity was evaluated by the thioredoxin activity fluorescent assay. The subcellular localization of Trx-1 and TBP-2 was evaluated by cellular immunofluorescence. The interaction between Trx-1 and TBP-2 was examined by co-immunoprecipitation. The cell viability was detected using CCK-8, and the expression of LC3-II/LC3-I was detected to evaluate the autophagy. The results showed that the mRNA levels of the Trx-1 and TBP-2 were kinetically changed after treatment with H2 O2 for different durations. Exposure to H2 O2 increased the expression of TBP-2 but not Trx-1, while the exposure inhibited Trx-1 activity. TBP-2 was co-localized with Trx-1, and exposure to H2 O2 increased the interaction between TBP-2 and Trx-1. Trx-1 overexpression enhanced the autophagic response under normal circumstances and it might regulate autophagy in the initial phase. This study demonstrates the differential role of Trx-1 in cellular oxidative stress response, oxidative stress increased Trx-1 interaction with TBP-2, and Trx-1/TBP-2 regulated the autophagic response in the initial phase through LC3-II.

Noncoding RNAs in cataract formation: Star molecules emerge in an endless stream.

For decades, research on the pathological mechanism of cataracts has usually focused on the abnormal protein changes caused by a series of risk factors. However, an entire class of molecules, termed non-coding RNA (ncRNA), was discovered in recent years and proven to be heavily involved in cataract formation. Recent studies have recognized the key regulatory roles of ncRNAs in cataracts by shaping cellular activities such as proliferation, apoptosis, migration and epithelial-mesenchymal transition (EMT). This review summarizes our current insight into the biogenesis, properties and functions of ncRNAs and then discusses the development of research on ncRNAs in cataracts. Considering the significant role of ncRNA in cataract formation, research on novel associated regulatory mechanisms is urgently needed, and the development of therapeutic alternatives for the treatment of cataracts seems promising.

Research Progress Concerning a Novel Intraocular Lens for the Prevention of Posterior Capsular Opacification.

Posterior capsular opacification (PCO) is the most common complication resulting from cataract surgery and limits the long-term postoperative visual outcome. Using Nd:YAG laser-assisted posterior capsulotomy for the clinical treatment of symptomatic PCO increases the risks of complications, such as glaucoma, retinal diseases, uveitis, and intraocular lens (IOL) pitting. Therefore, finding how to prevent PCO development is the subject of active investigations. As a replacement organ, the IOL is implanted into the lens capsule after cataract surgery, but it is also associated with the occurrence of PCO. Using IOL as a medium for PCO prophylaxis is a more facile and efficient method that has demonstrated various clinical application prospects. Thus, scientists have conducted a lot of research on new intraocular lens fabrication methods, such as optimizing IOL materials and design, and IOL surface modification (including plasma/ultraviolet/ozone treatment, chemical grafting, drug loading, coating modification, and layer-by-layer self-assembly methods). This paper summarizes the research progress for different types of intraocular lenses prepared by different surface modifications, including anti-biofouling IOLs, enhanced-adhesion IOLs, micro-patterned IOLs, photothermal IOLs, photodynamic IOLs, and drug-loading IOLs. These modified intraocular lenses inhibit PCO development by reducing the residual intraoperative lens epithelial cells or by regulating the cellular behavior of lens epithelial cells. In the future, more works are needed to improve the biosecurity and therapeutic efficacy of these modified IOLs.

Thin film nanoarchitectonics of layer-by-layer assembly with reduced graphene oxide on intraocular lens for photothermal therapy of posterior capsular opacification.

Due to development of surgical techniques and intraocular lens (IOL) implants, vision can often be restored in cataracts patients. However, posterior capsular opacification (PCO) has become the most common and challenging complication in cataracts surgery. While various approaches such as surface modification and drug prophylaxis have been investigated to prevent PCO development, there is no standard treatment that is sufficiently safe and effective to meet clinical demands. Near-infrared (NIR) light-triggered photothermal therapy is an attractive noninvasive treatment for PCO prophylaxis. We fabricated a new type of IOL with excellent biocompatibility, stability, and photothermal conversion property. Polyethyleneimine (PEI) and graphene oxide (GO) were layer-by-layer assembled on model polymethylmethacrylate and IOL substrates, and the thickness, surface roughness, and wettability of the substrates with different numbers of bilayers were evaluated. After the reduction of GO to reduced GO (rGO), a rGO/PEI multilayer thin film with good stability and photothermal conversion capability was obtained. The rGO/PEI multilayer coating was able to induce apoptosis in lens epithelium cells under 808-nm NIR laser irradiation in vitro. Finally, rGO@IOL was implanted into rabbit eyes, and the biocompatibility and ability to prevent PCO were evaluated for 5 weeks. The rGO@IOL implant exhibited excellent PCO prevention ability with the assistance of NIR irradiation and did not induce obvious pathological effects in surrounding healthy tissues. The rGO@IOL implant with good biocompatibility, good physicochemical stability, and excellent photothermal conversion property shows promise for clinical application in PCO prophylaxis.

CircRNA Is a Rising Star in Researches of Ocular Diseases.

A newly rediscovered subclass of noncoding RNAs, circular RNAs (circRNAs), is produced by a back-splicing mechanism with a covalently closed loop structure. They not only serve as the sponge for microRNAs (miRNAs) and proteins but also regulate gene expression and epigenetic modification, translate into peptides, and generate pseudogenes. Dysregulation of circRNA expression has opened a new chapter in the etiology of various human disorders, including cancer and cardiovascular, neurodegenerative, and ocular diseases. Recent studies recognized the vital roles that circRNAs played in the pathogenesis of various eye diseases, highlighting circRNAs as promising biomarkers for diagnosis and assessment of progression and prognosis. Interventions targeting circRNAs provide insights for developing novel treatments for these ocular diseases. This review summarizes our current perception of the properties, biogenesis, and functions of circRNAs and the development of circRNA researches related to ophthalmologic diseases, including diabetic retinopathy, age-related macular degeneration, retinopathy of prematurity, glaucoma, corneal neovascularization, cataract, pterygium, proliferative vitreoretinopathy, retinoblastoma, and ocular melanoma.

Femtosecond laser assisted cataract surgery in a cataract patient with a "0 vaulted" ICL: a case report.

BACKGROUND: Femtosecond laser assisted cataract surgery (FLACS) combined with implantable collamer lenses (ICLs) extraction has been shown to be a feasible method for patients developing cataracts after the ICL implantation. All reported cases had shallow vaults, ranging from 47 µm (µm) to 100 µm. We report for the first time, a case in which the FLACS was performed on the "0" vault eye. CASE PRESENTATION: A 38-year-old man with anterior subcapsular cataracts underwent the FLACS combined with ICLs extraction 6 years after ICLs implantation in both eyes. In his left eye, the ICL touched the anterior capsule, existing "0" vault. During the capsulotomy, cavitation bubbles were trapped in the shallow space beneath the ICL, developing from small bubbles into big ones, which resulted in the incomplete capsulotomy. Comparatively, in the right eye, the ICL vault was measured 72 µm, and the capsulotomy was complete and no big cavitation bubbles formed. In both eyes, capsulotomy zones were manually assigned to the anterior capsule surface in the process of laser identification. However, the nuclear pre-fragmentations were unsuccessful in both eyes. Other steps of surgeries were performed uneventfully. Depending on the design of monovision, the uncorrected distance visual acuity (UDVA) was 20/32, and the near uncorrected visual acuity (UCVA) was 20/25 in both eyes postoperatively. CONCLUSIONS: This case suggested that the surgeon should pay attention to the incomplete laser capsulotomy when using a femtosecond laser in cataractous cases with "0" vaulted ICLs, and manual adjustment was required in the process of laser identification.

Combination of gemcitabine-containing magnetoliposome and oxaliplatin-containing magnetoliposome in breast cancer treatment: A possible mechanism with potential for clinical application.

Breast cancer is a major global health problem with high incidence and case fatality rates. The use of magnetoliposomes has been suggested as an effective therapeutic approach because of their good specificity for cancers. In this study, we developed two novel magnetoliposomes, namely, Gemcitabine-containing magnetoliposome (GML) and Oxaliplatin-containing magnetoliposome (OML). These magnetoliposomes were combined (CGOML) was used to treat breast cancer under an external magnetic field. Biosafety test results showed that GML and OML were biologically safe to blood cells and did not adversely affect the behavior of mice. Pharmacokinetic and tissue distribution studies indicated that both magnetoliposomes exhibited stable structures and persisted at the target area under an external magnetic field. Cell and animal experiments revealed that CGOML can markedly suppress the growth of MCF-7 cells, and only the CGOML group can minimize the tumor size among all the groups. Finally, CGOML can significantly inhibit MCF-7cell growth both in vitro and vivo by activating the apoptotic signaling pathway of MCF-7 cells.