The Potential Role of Regulated Cell Death in Dry Eye Diseases and Ocular Surface Dysfunction

RIPK3 and RIPK1 gene expression in pterygium: unveiling molecular insights into pathogenesis

BACKGROUND

Pterygium, characterized by the abnormal proliferation of epithelial cells, matrix remodeling, vascularization, and lesion migration, is a prevalent ocular surface disease involving the growth of fibrovascular tissue on the cornea. Despite the unclear underlying causes of pterygium, numerous investigations have indicated the involvement of cell death pathways in the regulation of cell cycle dynamics. Consequently, the objective of this study was to assess the expression levels of necroptosis markers in individuals diagnosed with pterygium, aiming to shed light on the potential role of necroptosis in the pathogenesis of this condition.

METHODS

This study aimed to investigate the expression patterns of receptor-interacting serine/threonine kinase 3 (RIPK3) and receptor-interacting serine/threonine kinase 1 (RIPK1) genes in pterygium tissues. 41 patients undergoing pterygium excision surgery were recruited. Resected pterygium samples and normal conjunctival tissues were collected, and RIPK3 and RIPK1 mRNA levels were measured using quantitative real-time PCR.

RESULTS

Our findings reveal that the expression of RIPK3 is significantly increased in samples obtained from individuals with pterygium. However, no significant alterations were observed in the expression of RIPK1 in these samples. Results showed significantly higher RIPK3 expression in pterygium tissues compared to controls. Moreover, increased RIPK3 levels correlated negatively with pterygium recurrence rates.

CONCLUSIONS

These findings suggest RIPK3 may play a protective role against pterygium recurrence through necroptosis.

Potential New Target for Dry Eye Disease-Oxidative Stress

Dry eye disease (DED) is a multifactorial condition affecting the ocular surface. It is characterized by loss of tear film homeostasis and accompanied by ocular symptoms that may potentially result in damage to the ocular surface and even vision loss. Unmodifiable risk factors for DED mainly include aging, hormonal changes, and lifestyle issues such as reduced sleep duration, increased screen exposure, smoking, and ethanol consumption. As its prevalence continues to rise, DED has garnered considerable attention, prompting the exploration of potential new therapeutic targets. Recent studies have found that when the production of ROS exceeds the capacity of the antioxidant defense system on the ocular surface, oxidative stress ensues, leading to cellular apoptosis and further oxidative damage. These events can exacerbate inflammation and cellular stress responses, further increasing ROS levels and promoting a vicious cycle of oxidative stress in DED. Therefore, given the central role of reactive oxygen species in the vicious cycle of inflammation in DED, strategies involving antioxidants have emerged as a novel approach for its treatment. This review aims to enhance our understanding of the intricate relationship between oxidative stress and DED, thereby providing directions to explore innovative therapeutic approaches for this complex ocular disorder.

Purple Corn Extract Improves Dry Eye Symptoms in Models Induced by Desiccating Stress and Extraorbital Lacrimal Gland Excision

Dry eye disease (DED) occurs when there are not enough tears, and the associated symptoms-burns, itching, and a gritty feeling in the eye-can cause great discomfort. The purpose of this study was to evaluate the therapeutic effect of purple corn extract (PCE) on DED. Pretreatment with PCE prevented desiccation-stress-induced cell damage in human retinal pigment epithelial cells and primary human corneal epithelial cells. Furthermore, PCE reduced the mRNA expression of inflammatory mediators in the induction of desiccation stress. The therapeutic effects of PCE on DED were evaluated in an animal model with induced unilateral excision of the exorbital lacrimal gland. The administration of PCE was effective at recovering tear production, corneal surface irregularity, and conjunctival goblet cell density, as well as at reducing apoptotic cell death in the outer layer of the corneal epithelium. Collectively, PCE improved dry eye symptoms, and, therefore, it could be a potential agent to ameliorate and/or treat DED.

Development and validation of a multiplex electrochemiluminescence immunoassay to evaluate dry eye disease in rat tear fluids

Dry eye disease (DED) is a challenge in ophthalmology. Rat models represent valuable tools to study the pathophysiology and to develop novel treatments. A major challenge in DED research is detecting multiple biomarkers in a low tear volume sample. Multiplex immunoassays for DED rat research are missing. We have developed a multiplex electrochemiluminescence immunoassay (ECLIA) to detect three biomarkers for DED: MMP-9, IL-17 and ICAM-1. Tears, used as matrix, were collected from six healthy Wistar rats. Assays were run based on the U-Plex Meso Scale Diagnostics (MSD) platform, by two independent operators according to the EMA guideline on bioanalytical method validation. Linear mixed, regression models were fit to perform the statistical analysis on the range of concentrations for the chosen analytes. During optimization, it has observed that incubation time, temperature and agitation affected the robustness of the protocol. ECLIA optimum conditions include the use of antibodies at 0.5 µg/ml concentration and 1 h incubation at room temperature with shaking. Precision met the acceptance criteria in the chosen range: 1062-133 pg/ml for ICAM-1, 275-34.4 pg/ml for IL-17, 1750-219 pg/ml for MMP-9. Accuracy and linearity were acceptable for a broader range. This is the first report of a validated ECLIA that allows measurements of three relevant DED biomarkers in rat tear fluids.

GSK-3β-dependent Nrf2 antioxidant response modulates ferroptosis of lens epithelial cells in age-related cataract

Oxidative stress-induced lens epithelial cells (LECs) death plays a pivotal role in age-related cataract (ARC) with severe visual impairment, in which ferroptosis is gradually receiving numerous attention resulting from lipid peroxide accumulation and reactive oxygen species (ROS) overproduction. However, the essential pathogenic factors and the targeted medical strategies still remain skeptical and indistinct. In this work, by transmission electron microscopy (TEM) analysis, the major pathological courses in the LECs of ARC patients have been identified as ferroptosis, which was manifested with remarkable mitochondrial alterations, and similar results were found in aged mice (24-month-old). Furthermore, the primary pathological processes in the NaIO3-induced mice and HLE-B3 cell model have also been verified to be ferroptosis with an irreplaceable function of Nrf2, proved by the increased sensitivity to ferroptosis when Nrf2 was blocked in Nrf2-KO mice and si-Nrf2-treated HLE-B3 cells. Importantly, it has been found that an increased expression of GSK-3β was indicated in low-Nrf2-expressed tissues and cells. Subsequently, the contributions of abnormal GSK-3β expression to NaIO3-induced mice and HLE-B3 cell model were further evaluated, inhibition of GSK-3β utilizing SB216763 significantly alleviated LECs ferroptosis with less iron accumulation and ROS generation, as well as reversed expression alterations of ferroptosis markers, including GPX4, SLC7A11, SLC40A1, FTH1 and TfR1, in vitro and in vivo. Collectively, our findings conclude that targeting GSK-3β/Nrf2 balance might be a promising therapeutic strategy to mitigate LECs ferroptosis and thus probably delay the pathogenesis and development of ARC.