Biliverdin/Bilirubin Redox Pair Protects Lens Epithelial Cells against Oxidative Stress in Age-Related Cataract by Regulating NF-κB/iNOS and Nrf2/HO-1 Pathways

Slit2 Promotes H2O2-Induced Lens Epithelial Cells Oxidative Damage and Age-Related Cataract

PURPOSE

To analyze the role of Slit2 in lens epithelial cell oxidative damage and its underlying mechanism.

METHODS

Human lens epithelial cells (SRA01/04 cells) and rat transparent lens were cultured with H2O2 to establish cell oxidative stress models and rat cataract models. Immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot assays were employed to detect Slit2 levels within age-related cataracts(ARC) lens anterior capsule samples, rat cataract models, and cell oxidative stress models. In this study, qRT-PCR and Western blot assays were performed to derermine E-cadherin, N-cadherin, occludens1(ZO-1), α-SMA(α‑smooth muscle actin), Bcl-2, Bax, p-AKT, and AKT levels. In addition, Flow cytometry were performed to examine reactive oxygen species (ROS) and cell apoptosis. Cell viability, invasion, and migration were detected by CCK8, Transwell, and Wound healing.

RESULTS

Increased expression of Slit2 was found in ARC lens anterior capsule samples, H2O2-induced rat cataract models, and Human lens epithelial cells (HLECs) oxidative stress models. H2O2 significantly increased cell apoptosis and ROS generation, also accelerating cell migration, invasion, and epithelial-mesenchymal transition (EMT). In addition, H2O2 treatment repressed AKT phosphorylation and cell viability. Knock-down of Slit2 promoted cell viability and AKT phosphorylation levels, as well as repressed cell invasion, migration, apoptosis, ROS production and EMT.

CONCLUSION

Slit2 promoted lens epithelial cells oxidative stress damage via the AKT signalling pathways, providing a novel insight in ARC treatment.

Reactive oxygen species (ROS) scavenging biomaterials for anti-inflammatory diseases: from mechanism to therapy

Inflammation is a fundamental defensive response to harmful stimuli, but the overactivation of inflammatory responses is associated with most human diseases. Reactive oxygen species (ROS) are a class of chemicals that are generated after the incomplete reduction of molecular oxygen. At moderate levels, ROS function as critical signaling molecules in the modulation of various physiological functions, including inflammatory responses. However, at excessive levels, ROS exert toxic effects and directly oxidize biological macromolecules, such as proteins, nucleic acids and lipids, further exacerbating the development of inflammatory responses and causing various inflammatory diseases. Therefore, designing and manufacturing biomaterials that scavenge ROS has emerged an important approach for restoring ROS homeostasis, limiting inflammatory responses and protecting the host against damage. This review systematically outlines the dynamic balance of ROS production and clearance under physiological conditions. We focus on the mechanisms by which ROS regulate cell signaling proteins and how these cell signaling proteins further affect inflammation. Furthermore, we discuss the use of potential and currently available-biomaterials that scavenge ROS, including agents that were engineered to reduce ROS levels by blocking ROS generation, directly chemically reacting with ROS, or catalytically accelerating ROS clearance, in the treatment of inflammatory diseases. Finally, we evaluate the challenges and prospects for the controlled production and material design of ROS scavenging biomaterials.

Carbon Monoxide Releasing Molecule-3 Alleviates Oxidative Stress and Apoptosis in Selenite-Induced Cataract in Rats via Activating Nrf2/HO-1 Pathway

PURPOSE

This study investigated the protective effect of carbon monoxide releasing molecule-3 (CORM-3), the classical donor of carbon monoxide, on selenite-induced cataract in rats and explore its possible mechanism.

METHODS

Sprague-Dawley rat pups treated with sodium selenite (Na2SeO3) were chosen as the cataract model. Fifty rat pups were randomly divided into 5 groups: Control group, Na2SeO3 (3.46 mg/kg) group, low-dose CORM-3 (8 mg/kg/d) + Na2SeO3 group, high-dose CORM-3 (16 mg/kg/d) + Na2SeO3 group, and inactivated CORM-3 (iCORM-3) (8 mg/kg/d) + Na2SeO3 group. The protective effect of CORM-3 was tested by lens opacity scores, hematoxylin and eosin staining, TdT-mediated dUTP nick-end labeling assay, and enzyme-linked immunosorbent assay. Besides, quantitative real-time PCR and western blotting were used for mechanism validation.

RESULTS

Na2SeO3 induced nuclear cataract rapidly and stably, and the achievement ratio of Na2SeO3 group was 100%. CORM-3 alleviated lens opacity of selenite-induced cataract and attenuated the morphological changes of the rat lens. The levels of antioxidant enzymes GSH and SOD in rat lens were also increased by CORM-3 treatment. CORM-3 significantly reduced the ratio of apoptotic lens epithelial cells, besides, CORM-3 decreased the expression of Cleaved Caspase-3 and Bax induced by selenite and increased the expression of Bcl-2 in rat lens inhibited by selenite. Moreover, Nrf-2 and HO-1 were upregulated and Keap1 was downregulated after CORM-3 treatment. While iCORM-3 did not exert the same effect as CORM-3.

CONCLUSIONS

Exogenous CO released from CORM-3 alleviates oxidative stress and apoptosis in selenite-induced rat cataract via activating Nrf2/HO-1 pathway. CORM-3 may serve as a promising preventive and therapeutic strategy for cataract.

Toward nanotechnology-enabled application of bilirubin in the treatment and diagnosis of various civilization diseases

Bilirubin, an open chain tetrapyrrole, has powerful antioxidant, anti-inflammatory, immuno-suppressive, metabolic-modulating and anti-proliferative activities. Bilirubin is a natural molecule that is produced and metabolized within the human body, making it highly biocompatible and well suited for clinical use. However, the use of bilirubin has been hampered by its poor water solubility and instability. With advanced construction strategies, bilirubin-derived nanoparticles (BRNPs) have not only overcome the disadvantages of bilirubin but also enhanced its therapeutic effects by targeting damaged tissues, passing through physiological barriers, and ensuring controlled sustained release. We review the mechanisms underlying the biological activities of bilirubin, BRNP preparation strategies and BRNP applications in various disease models. Based on their superior performance, BRNPs require further exploration of their efficacy, biodistribution and long-term biosafety in nonhuman primate models that recapitulate human disease to promote their clinical translation.

Biliverdin Reductase A Protects Lens Epithelial Cells against Oxidative Damage and Cellular Senescence in Age-Related Cataract

Age-related cataract (ARC) is the common cause of blindness globally. Reactive oxygen species (ROS), one of the greatest contributors to aging process, leads to oxidative damage and senescence of lens epithelial cells (LECs), which are involved in the pathogenesis of ARC. Biliverdin reductase A (BVRA) has ROS-scavenging ability by converting biliverdin (BV) into bilirubin (BR). However, little is known about the protective effect of BVRA against ARC. In the present study, we measured the expression level of BVRA and BR generation in human samples. Then, the antioxidative property of BVRA was compared between the young and senescent LECs upon stress condition. In addition, we evaluated the effect of BVRA on attenuating H₂O₂-induced premature senescence in LECs. The results showed that the mRNA expression level of BVRA and BR concentration were decreased in both LECs and lens cortex of age-related nuclear cataract. Using the RNA interference technique, we found that BVRA defends LECs against oxidative stress via (i) restoring mitochondrial dysfunction in a BR-dependent manner, (ii) inducing heme oxygenase-1 (HO-1) expression directly, and (iii) promoting phosphorylation of ERK1/2 and nuclear delivery of nuclear factor erythroid 2-related factor 2 (Nrf2). Intriguingly, the antioxidative effect of BVRA was diminished along with the reduced BR concentration and repressed nuclear translocation of BVRA and Nrf2 in senescent LECs, which would be resulted from the decreased BVRA activity and impaired nucleocytoplasmic trafficking. Eventually, we confirmed that BVRA accelerates the G1 phase transition and prevents against H₂O₂-induced premature senescence in LECs. In summary, BVRA protects LECs against oxidative stress and cellular senescence in ARC by converting BV into BR, inducing HO-1 expression, and activating the ERK/Nrf2 pathway. This trial is registered with ChiCTR2000036059.