Structural Characteristics of the Lens in Presenile Cataract

Gold nanoparticles and induction of structural alteration and enhanced oxidative stress in rat lens

There is an emerging wide use of nanotechnology in the medical fields. The information regarding distribution and clearance of gold nanoparticles (AuNPs) in the ocular tissue is insufficient. We investigated the cumulative effect of AuNPs on rat lens structure and their effect on the redox state and aquaporin-0 (AQP0) expression. Thirty-six male rats were distributed as follow: control, AuNPs-200 (200 μg/kg/rat for 4-weeks) and AuNPs-500 (500 μg/kg/rat for 4-weeks) groups. Rats were euthanized after 4-weeks, and the eye lenses were investigated for histological studies, transmission and scanning electron microscopic studies, immunohistochemistry for AQP0 and morphometric measures. Lens homogenates were investigated for tumour necrosis factor-alpha (TNF-α) and total reactive oxygen species levels by ELISA and for p-c-SRC by western-blot. AuNPs administration induced morphological and ultrastructural changes in rat lens. Degenerative changes in the lens epithelium, cytoplasmic vacuoles, distorted separated cortical lens fibers and loss of ball-and-socket junctions were observed. A significant reduction of AQP0-immune-staining with a significant elevation of TNF-α, total ROS and p-c-SRC content in rat lens homogenates were detected as compared to the control group. Repetitive spherical 20 nm-sized AuNPs administration, especially at 500 μg/kg/rat, induced structural changes in lens fibers of rats and increased oxidative stress level in the lens tissue.

Targeted Activation of OGG1 Inhibits Paraptosis in Lens Epithelial Cells of Early Age-Related Cortical Cataract

Purpose

To investigate potential modes of programmed cell death in the lens epithelial cells (LECs) of patients with early age-related cortical cataract (ARCC) and to explore early-stage intervention strategies.

Methods

Anterior lens capsules were collected from early ARCC patients for comprehensive analysis. Ultrastructural examination of LECs was performed using transmission electron microscopy. Cell death-associated protein markers were quantified via Western blot analysis, including those for paraptosis (ALIX, GRP78), apoptosis (cleaved caspase 3 and caspase 9), pyroptosis (N-GSDMD), and ferroptosis (GPX4). Intracellular vesicle-organelle colocalization was assessed through immunofluorescence. OGG1 protein expression and activity were evaluated through multiple methods, including Western blot, laser micro-irradiation, and immunofluorescence. The therapeutic potential of the OGG1 activator TH10785 on paraptosis was investigated using an ex vivo rat lens model.

Results

Morphologic changes revealed significant endoplasmic reticulum (ER) swelling in ARCC patient LECs, with no characteristic apoptotic features. Paraptosis-related proteins exhibited significant alterations, while other cell death pathway markers (apoptosis, pyroptosis, and ferroptosis) remained unchanged. In the reactive oxygen species-induced paraptosis model, vesicular structures showed exclusive colocalization with ER-specific fluorescence. Elevated levels of the DNA damage marker 7,8-dihydro-8-oxoguanine were observed concurrent with decreased OGG1 activity. The OGG1 activator TH10785 showed efficacy in suppressing LECs paraptosis in ex vivo rat lens cultures.

Conclusions

Paraptosis was identified in the LECs of patients with early ARCC. TH10785 activates OGG1 to suppress paraptosis in LECs, suggesting a novel therapeutic approach for early ARCC intervention.

Histopathological findings of anterior lens capsule in pediatric cataract

PURPOSE

To investigate the histopathological findings of the anterior lens capsule in pediatric patients who had surgery for cataracts.

METHODS

This study is a prospective interventional study. Anterior capsule tissue samples that were obtained by the anterior capsulotomy method during phacoemulsification surgery were fixed and examined under a transmission electron microscope.

RESULTS

Twenty-two eyes of 19 patients who were diagnosed with congenital and juvenile cataracts were included in this study. Five patients had associated systemic diseases, including hydrocephalus, cerebral palsy, prematurity, juvenile myelomonocytic leukemia, and Down's syndrome. Electron microscopic evaluation demonstrated single-layered epithelium under the capsule, degenerated organelles with round-oval and prismatic-oval nuclei, and degenerated mitochondria and heterochromatin-rich nuclei. In the case with cerebral palsy, collagen fibrils of the connective tissue and fibroblast-like cells were observed replacing the epithelium that should be underneath the capsule in both eyes, and there was a disorganized distribution of collagen fibrils and vacuole structures in the cytoplasm of fibroblast-like cells.

CONCLUSION

Similar histopathological findings were found in pediatric cataracts with or without systemic disease except in one cerebral palsy case. The absence of lens epithelium may have been a result of degeneration in this patient, and this can be attributed to the presence of systemic inflammation and gliosis in cerebral palsy. The absence of lens epithelium can play a role in the development of dense subcapsular fibrosis and cataract formation.

Human Primary Lens Epithelial Cultures on Basal Laminas Studied by Synchrotron-Based FTIR Microspectroscopy for Understanding Posterior Capsular Opacification

Human primary lens epithelial cultures serve as an in vitro model for posterior capsular opacification (PCO) formation. PCO occurs when residual lens epithelial cells (LECs) migrate and proliferate after cataract surgery, differentiating into fibroblastic and lens fiber-like cells. This study aims to show and compare the bio-macromolecular profiles of primary LEC cultures and postoperative lens epithelia LECs on basal laminas (bls), while also analyzing bls and cultured LECs separately. Using synchrotron radiation-based Fourier transform infrared (SR-FTIR) (Bruker, Karlsruhe, Germany) microspectroscopy at the Spanish synchrotron light source ALBA, we observed that the SR-FTIR measurements were predominantly influenced by the strong collagen absorbance of the bls. Cultured LECs on bls showed a higher collagen contribution, indicated by higher vas CH3, CH2 and CH3 wagging and deformation, and the C-N stretching of collagen. In contrast, postoperative LECs on bls showed a higher cell contribution, indicated by the vsym CH2 peak and the ratio between vas CH2 and vas CH3 peaks. The primary difference revealed using SR-FTIR is the greater LEC contribution in spectra recorded from postoperative lens epithelia compared to cultured LECs on bls. IR spectra for bl, cultured LECs and postoperative lens epithelia could be valuable for future research.

Detecting Apoptotic Human Lens Epithelial Cells With Transmission Electron Microscopy

Introduction Cataract formation is a prevalent issue worldwide, and understanding the cellular processes involved is crucial to advancing treatment options. The scope of the study was to explore the presence of apoptotic cells in the lens epithelium of Greek patients with senile cataracts using transmission electron microscopy (TEM). Methods Twenty-one patients with senile cataracts were included in this cross-sectional study, and their anterior lens capsules were thoroughly examined. The presence of apoptosis was ultrastructurally investigated, and its association with age, gender, biomicroscopic type of cataract, the coexistence of exfoliation syndrome (XFS), diabetes mellitus, and glaucoma was statistically correlated. Results We detected apoptotic cells in nine of the 21 patients. Morphological features indicative of apoptosis in the nuclei included degradation, nuclear membrane irregularity, reduction of nuclear volume, condensation, and margination of chromatin. The cytoplasm either appeared denser or contained vacuoles. Budding with membrane blebbing and pinopode-like projections were frequently observed. Apoptotic cells appeared smaller, exhibiting loose connections with neighboring cells and the basement membrane (BM). Interestingly, apoptotic bodies were also detected. Conclusions None of the examined risk factors showed a connection to apoptosis, whereas neighboring lens epithelial cells (LECs) phagocytose apoptotic bodies, seemingly assumed the role of macrophages. Comparing apoptosis rates between populations with different sun exposure levels could help reveal the relationship between ultraviolet B radiation exposure, apoptosis, and cataract formation.

The lens epithelium as a major determinant in the development, maintenance, and regeneration of the crystalline lens

The crystalline lens is a transparent and refractive biconvex structure formed by lens epithelial cells (LECs) and lens fibers. Lens opacity, also known as cataracts, is the leading cause of blindness in the world. LECs are the principal cells of lens throughout human life, exhibiting different physiological properties and functions. During the embryonic stage, LECs proliferate and differentiate into lens fibers, which form the crystalline lens. Genetics and environment are vital factors that influence normal lens development. During maturation, LECs help maintain lens homeostasis through material transport, synthesis and metabolism as well as mitosis and proliferation. If disturbed, this will result in loss of lens transparency. After cataract surgery, the repair potential of LECs is activated and the structure and transparency of the regenerative tissue depends on postoperative microenvironment. This review summarizes recent research advances on the role of LECs in lens development, homeostasis, and regeneration, with a particular focus on the role of cholesterol synthesis (eg., lanosterol synthase) in lens development and homeostasis maintenance, and how the regenerative potential of LECs can be harnessed to develop surgical strategies and improve the outcomes of cataract surgery (Fig. 1). These new insights suggest that LECs are a major determinant of the physiological and pathological state of the lens. Further studies on their molecular biology will offer possibility to explore new approaches for cataract prevention and treatment.