New cataract markers: Mechanisms of disease

Sestrin2 Protects Human Lens Epithelial Cells (HLECs) Against Apoptosis in Cataracts Formation: Interaction Between Endoplasmic Reticulum (ER) Stress and Oxidative Stress (OS) is Involved

PURPOSE

To explore the correlation of endoplasmic reticulum stress (ERS) and oxidative stress (OS), and the protective effect of Sestrin2 (SESN2) on human lens epithelial cells (HLECs).

METHODS

Tunicamycin (TM) was used to induce ERS in HLECs. 4-Phenylbutyric acid (4-PBA) was used to inhibit ERS. Eupatilin applied to HLECs as SESN2 agonist. SESN2 expression was knocked down via si-RNA in HLECs. The morphological changes of HLECs were observed by microscope. ER-tracker to evaluate ERS, ROS production assay to measure ROS, flow cytometry to calculate cell apoptosis rate. Immunofluorescence to observe Nrf2 translocation, and effects of TM or EUP on SESN2. Western blot and qPCR were used to evaluate the expression of GRP78, PERK, ATF4, CHOP, Nrf2, and SESN2 expression in HLECs with different treatment groups.

RESULTS

ERS can elevate the expression of ROS and Nrf2 to induce OS. Upregulation of SESN2 was observed in ERS-mediate OS. Overexpression of SESN2 can reduce the overexpression of ERS-related protein GRP78, PERK, ATF4, proapoptotic protein CHOP, OS-related protein Nrf2, as well as ROS, and alleviate ERS injury at the same time. Whereas knockdown of SESN2 can upregulate the expression of GRP78, PERK, ATF4, CHOP, Nrf2, ROS, and deteriorate ERS damage.

CONCLUSIONS

ERS can induce OS, they form a vicious cycle to induce apoptosis in HLECs, which may contribute to cataract formation. SESN2 could protect HLECs against the apoptosis by regulating the vicious cycle between ERS and OS.

A bibliometric and visualized analysis of the pathogenesis of cataracts from 1999 to 2023

Research on the pathogenesis of cataracts is ongoing and the number of publications on this topic is increasing annually. This study offers an overview of the research status, popular topics, and scholarly tendencies in the field of cataract pathogenesis over recent decades，which helps to guide future research directions, and optimize resource allocation. In the present study, we performed a bibliometric analysis of cataract pathogenesis. Publications from January 1, 1999, to December 20, 2023, were collected from the Web of Science Core Collection (WoSCC), and the extracted data were quantified and analyzed. We analyzed and presented the data using Microsoft Excel, VOSviewer, CiteSpace, and Python. In all, 4006 articles were evaluated based on various characteristics, including publication year, authors, countries, institutions, journals, citations, and keywords. This study utilized VOSviewer to conduct visualized analysis, including co-authorship, co-citation, co-occurrence, and network visualization. The CiteSpace software was used to identify keywords with significant bursts of activity. The number of annual global publications climbed from 76 to 277 between 1999 and 2023, a 264.47% rise. Experimental Eye Research published the most manuscripts (178 publications), whereas Investigative Ophthalmology & Visual Science received the most citations (6675 citations). The most influential and productive country, institution, and author were the United States (1244 publications, 54,456 citations), University of California system (136 publications, 5401 citations), and Yao Ke (49 publications, 838 citations), respectively. The top 100 ranked keywords are divided into four clusters through co-occurrence analysis: (1) secondary cataracts, (2) oxidative stress, (3) gene mutations and protein abnormalities, and (4) alteration of biological processes in lens epithelial cells. Further discussions on the four subtopics outline the research topics and trends. In conclusion, the specific mechanism of cataract formation remains a popular topic for future research and should be explored in greater depth.

Conformational stability of the deamidated and mutated human βB2-crystallin

Previous studies propose that genetic mutations and post-translational modifications in protein crystallins promote protein aggregation and are considered significant risk factors for cataract formation. The βB2-crystallin (HβB2C) forms a high proportion of proteins in the human eye lens. Different congenital mutations and post-translational deamidations in βB2-crystallin have been reported and linked to cataract formation. In this work, we employed extensive all-atom molecular dynamics simulations to evaluate the conformational stability of deamidated and mutated HβB2C. Our results show critical changes in the protein surface and its native contacts due to a modification in the conformational equilibrium of these proteins. The double deamidated (Q70E/Q162E) and single deamidated (Q70E) impact the well compact conformation of the HβB2C. These post-translational modifications allow the exposure of the protein hydrophobic interface, which lead to the exposure of electronegative residues. On the other hand, our mutational studies showed that the S143F mutation modifies the hydrogen-bond network of an antiparallel β-sheet, unfolding the C-terminal domain. Interestingly, the chain termination mutation (Q155X) does not unfold the N-terminal domain. However, the resultant conformation is more compact and avoids the exposure of the hydrophobic interface. Our results provide valuable information about the first steps of HβB2C unfolding in the presence of deamidated amino acids that have been reported to appear during aging. The findings reported in this work are essential for the general knowledge of the initial steps in the cataract formation mechanism, which may be helpful for the further development of molecules with pharmacological potential against cataract disease.

Precise Detection of Cataracts with Specific High-Risk Factors by Layered Binary Co-Ionizers Assisted Aqueous Humor Metabolic Analysis

Diabetes and high myopia as well-known high-risk factors can aggravate cataracts, yet clinical coping strategy remains a bottleneck. Metabolic analysis tends to be powerful for precisely detection and mechanism exploration since most of diseases including cataracts are accompanied by metabolic disorder. Herein, a layered binary co-ionizers assisted aqueous humor metabolic analysis tool is proposed for potentially etiological typing and detection of cataracts, including age-related cataracts (ARC), cataracts with diabetes mellitus (CDM), and cataracts with high myopia (CHM). Startlingly, taking advantage of the optimal machine learning algorithm and all metabolic fingerprints, 100% of accuracy, precision, and recall rates are achieved for arbitrary comparison between groups. Moreover, 11, 9, and 7 key metabolites with explicit identities are confirmed as markers of discriminating CDM from ARC, CHM from ARC, and CDM from CHM, and the corresponding area under the curve values of validation cohorts are 0.985, 1.000, and 1.000. Finally, the critical impact of diabetes/high myopia on cataracts is revealed by excavating the change levels and metabolic pathways of key metabolites. This work updates the insights of prevention and treatment about cataracts at metabolic level and throws out huge surprises and progresses metabolic diagnosis toward a reality.

Apoptosis of Lens Epithelial Cells and Expression of NLRP3-related Proteins in Patients with Diabetes and Cataract

AIM

To compare the expression of apoptosis-related factors and Nlrp3-related proteins in the lens epithelial cells (LECs) of patients with diabetes and cataract and patients with age-related cataract (ARC) alone.

METHODS

All patients were divided into four groups according to the presence or absence of diabetes mellitus (DM) and the degree of diabetic retinopathy (DR). LECs were obtained during cataract surgery. The expression levels of cleaved caspase-3, caspase-7, ASC, caspase-1and Nlrp3 in LECs were determined. And analyzed by age, course of DM, and HbA1c levels.

RESULTS

The incidence of LEC apoptosis and positive rates of cleaved caspase-3 and caspase-7 expression were significantly higher in the groups with DM (P<0.05).The positive expression rates of ASC, caspase-1, and Nlrp3 increased with longer duration of DM, increased HbA1c level, or advanced DR (P<0.05).

CONCLUSION

In cataract patients with DM, the expression of apoptosis-related factors in LECs increased. Nlrp3-related protein expression levels, diabetes duration, HbA1c levels, and extent of DR may be potential risk factors for diabetic cataract formation.

Natural aldose reductase inhibitors for treatment and prevention of diabetic cataract: A review

Introduction: Aldose reductase (AR) is an enzyme that catalyzes the reduction of glucose to sorbitol responsible for the development of diabetic complications like cataracts. Medicinal plants contain several phytocompounds that can inhibit this enzyme.

Objective: The purpose of this review is to cite medicinal plants that have been tested for their ability to inhibit aldose reductase and consequently prevent cataracts and classify the major isolated compounds that have this activity.

Methods: We reviewed 154 articles published between 1954 and 2020 in English via three databases: ScienceDirect, Web of Science, and PubMed. We have classified the plants that showed a significant anti-cataract effect, in the form of a list including the scientific and family names of each plant. Also, we have cited the IC50 values and the active constituents of each plant that showed inhibitory activity towards AR.

Results: We have described 38 herbs belonging to 29 families. Besides, 47 isolated compounds obtained from the cited herbs have shown an AR inhibitory effect: luteolin, luteolin-7-O-β-D-glucopyranoside, apigenin, 3,5-di-O-caffeoyl-epi-quinic acid, delphinidin 3-O-β-galactopyranoside-3’-O-β-glucopyranoside, 3,5-di-O-caffeoylquinic acid methyl ester, andrographolide, 1,2,3,6-tetra-O-galloyl-β-D-glucose, 1,2,4,6-tetra-O-galloyl-β-D-glucose, 7-(3-hydroxypropyl)-3-methyl-8-β-O-D-glucoside-2H-chromen-2-one, E-4-(60-hydroxyhex-30-en-1-yl)phenyl propionate, delphinidin 3-O-β-galactopyranoside-3’,5’-di-O-β-glucopyranoside, 1,2,3-tri-O-galloyl-β-D-glucose, 1,2,3,4,6-penta-O-galloyl-β-D-glucose, 1,2,6-tri-O-galloyl-β-D-glucose, 2-(4-hydroxy-3-methoxyphenyl)ethanol, (4-hydroxy-3-methoxyphenyl)methanol, trans-anethole, gallic acid 4-O-β-D-(6’-O-galloyl)-glucoside, β-glucogallin, puerariafuran, quercetin, gallic acid 4-O-β-D-glucoside, 2,5-dihydroxybenzoic acid, 4-(4-hydroxy-3-methoxyphenyl)-2-butanone, protocatechuic acid, trans-cinnamic acid, gallic acid, p-coumaric acid and syringic acid.

Conclusion: natural therapy becomes an interesting alternative in the treatment and prevention of cataract by using medicinal plants rich in active compounds considered as AR inhibitors.

The potential health benefits of dietary natural plant products in age related eye diseases

In the past decade, there has been a tremendous increase in the number of cases of age-related eye diseases such as age-related macular degeneration (AMD), cataract, diabetic retinopathy and glaucoma. These diseases are the leading causes of visual impairment and blindness all over the world and are associated with many pathological risk factors such as aging, pollution, high levels of glucose (hyperglycaemia), high metabolic rates, and light exposure. These risk factors lead to the generation of uncontrollable reactive oxygen species (ROS), which causes oxidative stress. Oxidative stress plays a crucial role in the pathogenesis of age-related eye diseases through the activation of nuclear factor kappa B (NF-κB), vascular endothelial growth factor (VEGF), and lipid peroxidation, which leads to the production of inflammatory cytokines, angiogenesis, protein and DNA damages, apoptosis that causes macular degeneration (AMD), cataract, diabetic retinopathy and glaucoma. This review provides updated information on the beneficial effects of dietary natural plant products (DPNPs) against age-related eye diseases. In this review, supplementation of DPNPs demonstrated preventive and therapeutic effects on people at risk of or with age-related eye diseases due to their capacity to scavenge free radicals, ameliorate inflammatory molecules, neutralize the oxidation reaction that occurs in photoreceptor cells, decrease vascular endothelial growth factor and the blood-retinal barrier and increase the antioxidant defence system. However, further experiments and clinical trials are required to establish the daily doses of DPNPs that will safely and effectively prevent age-related eye diseases.

A Novel Mutation p.S93R in CRYBB1 Associated with Dominant Congenital Cataract and Microphthalmia

Purpose: To identify the pathogenetic mutations in a four-generation Chinese family with dominant congenital cataracts and microphthalmia.Methods: A four-generation Chinese family with dominant congenital cataracts were recruited. Genomic DNAs were collected from their peripheral blood leukocytes and subjected to whole exome sequencing. The genetic mutations were identified by bioinformatic analyses and verified by Sanger sequencing.Results: Whole exome sequencing revealed a c.279C>G point mutation in the CRYBB1 gene which was further verified by Sanger sequencing. The nucleotide replacement results in a novel mutation p.S93R in a conserved residue of βB1 crystallin which is predicted to disrupt normal βB1 structure and function.Conclusions: We identified a novel missense mutation p.S93R in CRYBB1 in a Chinese family with autosomal dominant congenital cataracts and microphthalmia. This serine residue is extremely conserved evolutionarily in more than 50 βγ-crystallins of many species. These data will be very helpful to further understand the structural and functional features of crystallins.