Ferroptosis Contributes to Microvascular Dysfunction in Diabetic Retinopathy.

Ferroptosis is a new form of cell death characterized by iron-dependent lipid peroxidation. Whether ferroptosis is involved in retinal microvascular dysfunction under diabetic condition is not known. Herein, the expression of ferroptosis-related genes in patients with proliferative diabetic retinopathy and in diabetic mice was determined with quantitative RT-PCR. Reactive oxygen species, iron content, lipid peroxidation products, and ferroptosis-associated proteins in the cultured human retinal microvascular endothelial cells (HRMECs) and in the retina of diabetic mice were examined. The association of ferroptosis with the functions of endothelial cells in vitro was evaluated. After administration of ferroptosis-specific inhibitor, Fer-1, the retinal microvasculature in diabetic mice was assessed. Characteristic changes of ferroptosis-associated markers, including glutathione peroxidase 4, ferritin heavy chain 1, long-chain acyl-CoA synthetase 4, transferrin receptor protein 1, and cyclooxygenase-2, were detected in the retinal fibrovascular membrane of patients with proliferative diabetic retinopathy, cultured HRMECs, and the retina of diabetic mice. Elevated levels of reactive oxygen species, lipid peroxidation, and iron content were found in the retina of diabetic mice and in cultured HRMECs. Ferroptosis was found to be associated with HRMEC dysfunction under high-glucose condition. Inhibition of ferroptosis with specific inhibitor Fer-1 in diabetic mice significantly reduced the severity of retinal microvasculopathy. Ferroptosis contributes to microvascular dysfunction in diabetic retinopathy, and inhibition of ferroptosis might be a promising strategy for the therapy of early-stage diabetic retinopathy.

Down-regulation of HuR inhibits pathological angiogenesis in oxygen-induced retinopathy.

HuR (also known as ELAV1), a ubiquitous RNA-binding protein, is implicated in the pathogenesis of diverse diseases via the mechanism of post-transcriptional regulation. Whether it is involved in pathological angiogenesis in oxygen-induced retinopathy is not clear. In this study, we detected HuR expression was increased in the retina of mouse model of oxygen-induced retinopathy (OIR) as well as in vascular endothelial cells exposed to hypoxia. With gain-of-function and loss-of-function studies using adenovirus infection, we found HuR over-expression promoted while HuR knockdown inhibited the migration, proliferation and tube formation of vascular endothelial cells. Moreover, HuR regulated the expression of VEGFA in vascular endothelial cells. We also found the retinal pathological angiogenesis in mouse OIR model was greatly reduced with HuR knockdown using recombinant AAV expressing HuR specific shRNA which was administered by intravitreal injection. The results of this study suggest HuR is involved in pathological angiogenesis via regulating angiogenic behaviors of endothelial cells, providing a potential target for the treatment of retinopathy of prematurity.

Ferrostatin-1 attenuates pathological angiogenesis in oxygen-induced retinopathy via inhibition of ferroptosis.

Retinopathy of prematurity (ROP) is a vision-threatening ocular disease that occurs in premature infants, but the underlying mechanism is still unclear. Since oxidative stress has been well documented in the ROP development, we aimed to investigate whether ferroptosis, a new type of cell death characterized by lipid peroxidation and iron overload, is also involved in ROP. We detected the lipid peroxidation, oxidative stress and the expression of ferroptosis markers in the retina of mouse model of oxygen-induced retinopathy. After ferroptosis inhibitor, ferrostatin-1, was administered by intravitreal injection, ferroptosis marker, lipid peroxidation, retinal vasculature and glial cell activation were examined. We found decreased expression of SLC7A11 and GPX4, increased expression of FTH1 and TFRC, as well as increase of lipid peroxidation in the retina of OIR mice. Ferrostatin-1 administration significantly reduced lipid peroxidation, and also reversed the change of ferroptosis marker. Neovascular area and avascular area were suppressed and the pathological vasculature changes including acellular vessels and ghost pericytes were decreased. Microglial cell and Müller cell activation was not evidently influenced by ferrostatin-1 treatment. Our findings suggest that ferroptosis is involved in the pathological angiogenesis and might be a promising target for ROP therapy.

Cost-effectiveness of artificial intelligence screening for diabetic retinopathy in rural China.

BACKGROUND: Diabetic retinopathy (DR) has become a leading cause of global blindness as a microvascular complication of diabetes. Regular screening of diabetic retinopathy is strongly recommended for people with diabetes so that timely treatment can be provided to reduce the incidence of visual impairment. However, DR screening is not well carried out due to lack of eye care facilities, especially in the rural areas of China. Artificial intelligence (AI) based DR screening has emerged as a novel strategy and show promising diagnostic performance in sensitivity and specificity, relieving the pressure of the shortage of facilities and ophthalmologists because of its quick and accurate diagnosis. In this study, we estimated the cost-effectiveness of AI screening for DR in rural China based on Markov model, providing evidence for extending use of AI screening for DR. METHODS: We estimated the cost-effectiveness of AI screening and compared it with ophthalmologist screening in which fundus images are evaluated by ophthalmologists. We developed a Markov model-based hybrid decision tree to analyze the costs, effectiveness and incremental cost-effectiveness ratio (ICER) of AI screening strategies relative to no screening strategies and ophthalmologist screening strategies (dominated) over 35 years (mean life expectancy of diabetes patients in rural China). The analysis was conducted from the health system perspective (included direct medical costs) and societal perspective (included medical and nonmedical costs). Effectiveness was analyzed with quality-adjusted life years (QALYs). The robustness of results was estimated by performing one-way sensitivity analysis and probabilistic analysis. RESULTS: From the health system perspective, AI screening and ophthalmologist screening had incremental costs of $180.19 and $215.05 but more quality-adjusted life years (QALYs) compared with no screening. AI screening had an ICER of $1,107.63. From the societal perspective which considers all direct and indirect costs, AI screening had an ICER of $10,347.12 compared with no screening, below the cost-effective threshold (1-3 times per capita GDP of Chinese in 2019). CONCLUSIONS: Our analysis demonstrates that AI-based screening is more cost-effective compared with conventional ophthalmologist screening and holds great promise to be an alternative approach for DR screening in the rural area of China.

Changes in Conjunctival Microbiota Associated With HIV Infection and Antiretroviral Therapy.

Purpose: HIV infection is associated with a variety of ocular surface diseases. Understanding the difference of the ocular microbiota between HIV-infected and healthy individuals as well as the influence of antiretroviral therapy will help to investigate the pathogenesis of these conditions. Methods: A cross-sectional study was conducted on subjects including HIV-negative individuals, untreated HIV-infected individuals, and HIV-infected individuals with antiretroviral therapy. Conjunctival microbiota was assessed by bacterial 16S rRNA sequencing of the samples obtained from the conjunctival swab. Results: The microbial richness in ocular surface was similar in HIV-negative, untreated HIV-positive, and highly active antiretroviral therapy (HAART) subjects. The bacterial compositions were similar in the two HIV infection groups but were significantly different from the HIV-negative group. HAART changed the beta diversity of bacterial community as determined by Shannon index. CD4+ T cell count had no significant influence on the diversity of ocular microbiota in HIV-infected individuals. Conclusions: The data revealed the compositional and structural difference in conjunctival microbial community in subjects with and without HIV infection, indicating that HIV infection or its treatment, may contribute to ocular surface dysbiosis.