基于肠-眼轴代谢调控与视网膜细胞铁死亡的糖尿病性黄斑水肿抗VEGF治疗耐药机制、增效干预策略及精准用药预测模型研究

Purpose The purpose of this study was to evaluate clinical reports of response-loss in patients with neovascular eye diseases, such as neovascular age-related macular degeneration (AMD) and diabetic macular edema (DME), after repeated anti-vascular endothelial growth factor (VEGF) therapy. To assess experimental evidence of associations of other angiogenic growth factors and endothelial glycolytic pathways with the diseases and to propose the underlying mechanisms. Methods Review of published clinical studies and experimental investigations. Results Intravitreal injection of anti-VEGF biologic drugs (e.g. bevacizumab, ranibizumab, and aflibercept) is the front-line treatment for neovascular AMD and DME, and acts by halting the progression of excess blood vessel growth and leakage. Despite favorable clinical results, exudation returns in a number of patients after repeated administrations over time. Patients suffering from disease recurrence may have developed an acquired resistance to anti-VEGF therapy. We have analyzed clinical and preclinical findings on changes to angiogenic signaling pathways following VEGF-targeted treatment and hypothesize that switching to alternative pathways could potentially bypass VEGF blockade, accounting for development of resistance to anti-VEGF therapy. We have also discussed potential reprogramming of ocular endothelial glycolysis in response to VEGF antagonism and proposed that metabolic adaptations could impair blood-retinal barrier function, counteracting the clinical efficacy of VEGF-targeted therapies and contributing to a decline of response to them. Conclusions Future studies of the mechanisms proposed in this review may shed some light on how these adaptations result in the development of acquired resistance to anti-VEGF therapy, which should help discover new therapeutic strategies for overcoming anti-VEGF resistance and improving clinical efficacy.

Diabetic retinopathy (DR), a leading cause of global blindness, represents a significant microvascular complication of diabetes mellitus. This comprehensive review examines the evolving landscape of monoclonal antibody (mAb) therapy in DR management. The pathogenesis of DR involves complex molecular mechanisms including VEGF overexpression, angiopoietin dysregulation, inflammatory processes, and oxidative stress. The angiopoietin–Tie (Ang/Tie) axis is a master regulator of endothelial stability; Ang-2–driven suppression of Tie2 promotes vascular leak, pericyte dropout, and leukocyte adhesion, providing a mechanistic rationale for Ang-2 inhibition and dual VEGF/Ang-2 blockade. Anti-VEGF mAbs (bevacizumab, aflibercept, ranibizumab) have revolutionized DR treatment by effectively targeting neovascularization and vascular permeability. Recent clinical innovations include ophthalmic formulations of bevacizumab, high-dose aflibercept, the ranibizumab port delivery system, and bispecific antibodies like faricimab that simultaneously target VEGF and angiopoietin-2 pathways, alongside emerging preclinical investigations into novel targets and bio-engineered delivery platforms. While anti-inflammatory mAbs targeting IL-6, IL-17A, and IL-1β show theoretical promise, clinical evidence supporting their efficacy remains limited, positioning them as agents under therapeutic development rather than established care. Despite therapeutic advances, significant challenges persist, including cost-effectiveness concerns, treatment burden, and adherence issues. This review highlights the transformative impact of mAb therapy in DR management while acknowledging the need for continued innovation to address existing limitations and optimize patient outcomes through personalized treatment approaches.

Diabetic retinopathy is the leading cause of blindness in working age adults, and is projected to be a significant future health concern due to the rising incidence of diabetes. The recent advent of anti-vascular endothelial growth factor (VEGF) antibodies has revolutionized the treatment of diabetic retinopathy but a significant subset of patients fail to respond to treatment. Accumulating evidence indicates that inflammatory cytokines and chemokines other than VEGF may contribute to the disease process. The current review examines the presence of non-VEGF cytokines in the eyes of patients with diabetic retinopathy and highlights mechanistic pathways in relevant animal models. Finally, novel drug targets including components of the kinin–kallikrein system and emerging treatments such as anti-HPTP (human protein tyrosine phosphatase) β antibodies are discussed. Recognition of non-VEGF contributions to disease pathogenesis may lead to novel therapeutics to enhance existing treatments for patients who do not respond to anti-VEGF therapies.

Purpose Identify optimal metabolic features and pathways across diabetic retinopathy (DR) stages, develop risk models to differentiate diabetic macular edema (DME), and predict anti-vascular endothelial growth factor (anti-VEGF) therapy response. Methods We analyzed 108 aqueous humor samples from 78 type 2 diabetes mellitus patients and 30 healthy controls. Ultra-high-performance liquid chromatography–high-resolution-mass-spectrometry detected lipidomics and metabolomics profiles. DME patients received ≥3 anti-VEGF treatments, categorized into strong and weak response groups. Machine learning (ML) screened prospective metabolic features, developing prediction models. Results Key metabolic features identified in the metabolomics and lipidomics datasets included n-acetyl isoleucine (odds ratio [OR] = 1.635), cis-aconitic acid (OR = 3.296), and ophthalmic acid (OR = 0.836) for DR. For early-DR, n-acetyl isoleucine (OR = 1.791) and decaethylene glycol (PEG-10) (OR = 0.170) were identified as key markers. L-kynurenine (OR = 0.875), niacinamide (OR = 0.843), and linoleoyl ethanolamine (OR = 0.941) were identified as significant indicators for DME. Trigonelline (OR = 1.441) and 4-methylcatechol-2-sulfate (OR = 1.121) emerged as predictors for strong response to anti-VEGF. Predictive models achieved R² values of 99.9%, 97.7%, 93.9%, and 98.4% for DR, early-DR, DME, and strong response groups in the calibration set, respectively, and validated well with R² values of 96.3%, 96.8%, 79.9%, and 96.3%. Conclusions This research used ML to identify differential metabolic features from metabolomics and lipidomics datasets in DR patients. It implies that metabolic indicators can effectively predict early disease progression and potential weak responders to anti-VEGF therapy in DME eyes. Translational Relevance The identified metabolic indicators may aid in predicting the early progression of DR and optimizing therapeutic strategies for DME.

Abstract The microbiome has become a hot issue in recent years. The composition, modification, alteration, and disturbance of gut microbiota were found to influence important physiological processes, including energy metabolism and microenvironmental homeostasis, and lead to various diseases, including obesity, type 2 diabetes mellitus and chronic kidney disease. Diabetic retinopathy (DR) is a major microvascular complication of diabetes mellitus and one of the leading causes of blindness and vision impairment. The underlying mechanisms in DR pathogenesis remain limited. Recently, important insights have been made regarding possible connections between gut microbiome dysbiosis and ocular disease including DR, uveitis, glaucoma, and age-related macular degeneration, and the concept of a “microbiota–gut–retina axis” has been put forward. Hence, we reviewed current understanding of the relationship between DR and gut microbiota. We summarized potential pathophysiological mechanisms that contribute to the role of the gut microbiota on DR, including hyperglycemia, anti-diabetes drugs, microbial metabolites, and inflammatory properties. We aimed to find novel effective therapeutic options to prevent the onset and development of DR.

Diabetic retinopathy (DR), a prominent microvascular impairment arising from diabetes, causes substantial visual dysfunction. Emerging evidence indicates that intestinal dysbiosis promotes DR progression via the gut-retina axis. Short-chain fatty acids serve a critical function in regulating gut microbiota, and propionate, a vital member of them, has potential translational value in DR prevention and management through the gut-retina axis. This review summarizes the impact of propionate on the retinal microenvironment by regulating gut microbiota and metabolites, focusing on its mechanisms influencing DR development, including modulating inflammation, protecting blood vessels, regulating immunity, exerting neuroprotection, and combating oxidative stress. It provides insights for devising propionate-based therapeutic strategies against DR.

BACKGROUND: Current approaches for the therapy of diabetic retinopathy (DR), which was one of leading causes of visual impairment, have their limitations. Animal experiments revealed that restructuring of intestinal microbiota can prevent retinopathy. AIM: To explore the relationship between intestinal microbiota and DR among patients in the southeast coast of China, and provide clues for novel ways to prevention and treatment methods of DR. METHODS: = 7). Spearman correlation analyses were performed to explore the associations between intestinal microbiota and clinical indicators. RESULTS: < 0.01). CONCLUSION: Our findings indicated that the alteration of gut microbiota was associated with DR and its severity among patients in the southeast coast of China, probably by multiple mechanisms such as producing short-chain fatty acids, influencing permeability of blood vessels, affecting levels of vascular cell adhesion molecule-1, hypoxia-inducible factor-1, B cell and insulin. Modulating gut microbiota composition might be a novel strategy for prevention of DR, particularly PDR in population above.

Diabetic retinopathy (DR) is a progressive, multifactorial complication of diabetes and one of the major global causes of visual impairment. Its pathogenesis involves chronic hyperglycaemia-induced oxidative stress, inflammation, mitochondrial dysfunction, neurodegeneration, and pathological angiogenesis, as well as emerging systemic contributors such as gut microbiota dysregulation. While current treatments, including anti-vascular endothelial growth factor (anti-VEGF) agents, corticosteroids, and laser photocoagulation, have shown clinical efficacy, they are largely limited to advanced stages of DR, require repeated invasive procedures, and do not adequately address early neurovascular and metabolic abnormalities. Resveratrol (RSV), a naturally occurring polyphenol, has emerged as a promising candidate due to its potent antioxidant, anti-inflammatory, neuroprotective, and anti-angiogenic properties. This review provides a comprehensive analysis of the molecular mechanisms by which RSV exerts protective effects in DR, including modulation of oxidative stress pathways, suppression of inflammatory cytokines, enhancement of mitochondrial function, promotion of autophagy, and inhibition of pathological neovascularisation. Despite its promising pharmacological profile, the clinical application of RSV is limited by poor aqueous solubility, rapid systemic metabolism, and low ocular bioavailability. Various routes of administration, including intravitreal injection, topical instillation, and oral and sublingual delivery, have been investigated to enhance its therapeutic potential. Recent advances in drug delivery systems, including nanoformulations, liposomal carriers, and sustained-release intravitreal implants, offer potential strategies to address these challenges. This review also explores RSV’s role in combination therapies, its potential as a disease-modifying agent in early-stage DR, and the relevance of personalised medicine approaches guided by metabolic and genetic factors. Overall, the review highlights the therapeutic potential and the key translational challenges in positioning RSV as a multi-targeted treatment strategy for DR.

Anti-angiogenic therapy with anti-vascular endothelial growth factor (anti-VEGF) is currently the first-line treatment for macular edema (ME), but the specific metabolic changes in the aqueous humor (AH) after intravitreal anti-VEGF injections remain poorly understood. A total of 120 AH samples from 60 ME patients before and after anti-VEGF treatment were collected from the ophthalmology clinic and ward of the Eye Hospital of Wenzhou Medical University. Non-targeted metabolomics analysis of the AH samples was performed using liquid chromatography-tandem mass spectrometry (LC–MS/MS). Orthogonal partial least squares discriminant analysis (OPLS-DA) was used to identify metabolite differences before and after anti-VEGF treatment in patients with different ME etiologies. Distinct metabolomic profiles were observed between pre- and post-treatment samples. A total of 145 significantly altered metabolites were identified after anti-VEGF treatment, with 84 upregulated metabolites related to carbohydrate and amino acid metabolism, and 61 downregulated metabolites involved in amino acid metabolism. Both common and etiology-specific metabolic alterations were observed. In age-related macular degeneration (AMD)-ME, treatment-induced metabolic changes mainly involved amino acid metabolism, whereas in branch retinal vein occlusion (BRVO)-ME, lipid metabolism was primarily affected. Diabetic macular edema (DME) patients showed more complex metabolic alterations, involving amino acid, lipid and carbohydrate metabolism. Intravitreal anti-VEGF injections significantly alter AH metabolites in ME patients. These findings provide insight into underlying metabolic processes in ME pathogenesis and treatment efficacy.

Diabetic macular edema (DME), a sight-threatening retinopathy, is a leading cause of vision loss in persons with diabetes mellitus. Despite strict control of systemic risk factors, a fraction of patients with diabetes developed DME, suggesting the existence of other potential pathogenic factors underlying DME. This study aimed to investigate the plasma metabotype of patients with DME and to identify novel metabolite markers for DME. Biomarkers identified from this study will provide scientific insight and new strategies for the early diagnosis and intervention of DME. To match clinical parameters between case and control subjects, patients with DME (DME, n = 30) or those with diabetes but without DME (Control, n = 30) were assigned to the present case-control study. Distinct metabolite profiles of serum were examined using liquid chromatography-mass spectrometry (LC-MS). A total of 190 distinct metabolites between DME and Control groups were identified (VIP > 1, Fold Change > 1.5 or < 0.667, and P < 0.05). The distinct metabolites between DME and Control groups were enriched in 4 KEGG pathways, namely, Glutamate Metabolism, Carnitine Synthesis, Oxidation of Branched Chain Fatty Acids, and Phytanic Acid Peroxisomal Oxidation. Finally, 4 metabolites were selected as candidate biomarkers for DME, namely, 5-Phospho-beta-D-ribosylamine, Succinic acid, Ascorbyl glucoside, and Glutathione disulfide. The area under the curve for these biomarkers were 0.693, 0.772, 0.762, and 0.771, respectively. This study suggested that impairment in the metabolism and 4 potential metabolites were identified as metabolic dysregulation associated with DME, which might provide insights into potential new pathogenic pathways for DME. 5-Phospho-beta-D-ribosylamine was first identified as a novel metabolite marker, with no previous reports linking it to diabetes or DME. This discovery may offer valuable insights into potential new pathogenic pathways associated with DME.

Background Macular edema (ME) is a major complication of retinal disease with multiple mechanisms involved in its development. This study aimed to investigate the metabolite profile of aqueous humor (AH) in patients with ME of different etiologies and identify potential metabolite biomarkers for early diagnosis of ME. Methods Samples of AH were collected from 60 patients with ME and 20 age- and sex-matched controls and analyzed by liquid chromatography-mass spectrometry (LC/MS)-based metabolomics. A series of univariate and multivariate statistical analyses were performed to identify differential metabolites and enriched metabolite pathways. Results The metabolic profile of AH differed significantly between ME patients and healthy controls, and differentially expressed metabolites were identified. Pathway analysis revealed that these differentially expressed metabolites are mainly involved in lipid metabolism and amino acid metabolism. Moreover, significant differences were identified in the metabolic composition of AH from patients with ME due to different retinal diseases including age-related macular degeneration (AMD-ME), diabetic retinopathy (DME) and branch retinal vein occlusion (BRVO-ME). In total, 39 and 79 etiology-specific altered metabolites were identified for AMD-ME and DME, respectively. Finally, an AH-derived machine learning-based diagnostic model was developed and successfully validated in the test cohort with an area under the receiver operating characteristic (ROC) curve of 0.79 for AMD-ME, 0.94 for DME and 0.77 for BRVO-ME. Conclusions Our study illustrates the potential underlying metabolic basis of AH of different etiologies across ME populations. We also identify AH-derived metabolite biomarkers that may improve the differential diagnosis and treatment stratification of ME patients with different etiologies.

Diabetic retinopathy (DR), with increasing incidence, is the major cause of vision loss and blindness worldwide in working-age adults. Diabetic macular edema (DME) remains the main cause of vision impairment in diabetic patients, with its pathogenesis still not completely elucidated. Vascular endothelial growth factor (VEGF) plays a pivotal role in the pathogenesis of DR and DME. Currently, intravitreal injection of anti-VEGF agents remains as the first-line therapy in DME treatment due to the superior anatomic and functional outcomes. However, some patients do not respond satisfactorily to anti-VEGF injections. More than 30% patients still exist with persistent DME even after regular intravitreal injection for at least 4 injections within 24 weeks, suggesting other pathogenic factors, beyond VEGF, might contribute to the pathogenesis of DME. Recent advances showed nearly all the retinal cells are involved in DR and DME, including breakdown of blood-retinal barrier (BRB), drainage dysfunction of Müller glia and retinal pigment epithelium (RPE), involvement of inflammation, oxidative stress, and neurodegeneration, all complicating the pathogenesis of DME. The profound understanding of the changes in proteomics and metabolomics helps improve the elucidation of the pathogenesis of DR and DME and leads to the identification of novel targets, biomarkers and potential therapeutic strategies for DME treatment. The present review aimed to summarize the current understanding of DME, the involved molecular mechanisms, and the changes in proteomics and metabolomics, thus to propose the potential therapeutic recommendations for personalized treatment of DME.

Background: Diabetic macular edema (DME) is a leading cause of vision impairment and blindness among diabetic patients, requiring effective diagnostic and monitoring strategies. This systematic review aims to synthesize current knowledge on molecular biomarkers associated with DME, focusing on their potential to improve diagnostic accuracy and disease management. Methods: A comprehensive search was conducted in PubMed, Embase, Medline, and the Cochrane Central Register of Controlled Trials, covering literature from 2004 to 2023. Out of 1074 articles initially identified, 48 relevant articles were included in this systematic review. Results: We found that molecules involved in several cellular processes, such as neuroinflammation, oxidative stress, vascular dysfunction, apoptosis, and cell-to-cell communication, exhibit differential expression profiles in various biological fluids when comparing diabetic individuals with or without macular edema. Conclusions: The study of these molecules could lead to the proper identification of specific biomarkers that may improve the diagnosis, prognosis, and therapeutic management of DME patients.

Diabetic macular edema (DME) has become a global public health focus due to its increasing prevalence and significant impact on central vision. The aim of this study is to analyze the lipid profile characteristics of aqueous humor in DME patients and to identify differential lipid compounds that may serve as potential biomarkers for the pathogenesis and therapeutic intervention. A non-targeted lipidomics approach based on liquid chromatography–tandem mass spectrometry (LC–MS/MS) was used to analyze the lipid profiles of aqueous humor from patients with diabetic macular edema (DME group, 11 cases), diabetic cataracts (DC group, 14 cases), and age-related cataract (ARC group, 15 cases). The validation of identified lipid compounds through Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) was conducted to examine possible varied lipid markers, setting the parameters of VIP > 1 and p < 0.05. Additionally, correlation network analysis, community classification, and functional enrichment analysis were performed on the differential lipids. 90 lipid compounds were identified, encompassing a range of 13 lipid categories. There were significant differences in the lipid profiles of the aqueous humor in DME. The lipid profile characteristics of aqueous humor in patients with DME are described for the first time. Compared to the control group. Various lipid metabolic disorders, such as sphingolipids particularly ceramide, phospholipids, and triglycerides, are involved in the pathogenesis of DME, and can be further studied as potential diagnostic and therapeutic lipid biomarkers.

Diabetic retinopathy (DR) is a microvascular complication of diabetes with its exact underlying mechanisms have not been fully elucidated. This study aimed to investigate the effects of key proteins and metabolites on the development of DR. Undiluted vitreous fluid samples were collected from eight patients with proliferative diabetic retinopathy (PDR) and six non-diabetic idiopathic macular hole (iMH) controls. Integration of TMT-tagged quantitative proteomics and untargeted metabolomics analyses was combined with bioinformatics approaches (PCA, differential expression, PPI network, OPLS-DA, pathway enrichment). Key results were validated by ELISA, immunohistochemistry, and cell proliferation and migration assays. Seven key proteins with six key metabolites were identified to be significantly dysregulated in the PDR. In the vitreous body and retinal nerve fiber layer of the DR group, CD5L expression was upregulated, while CLU was downregulated with SERPINF1 (PEDF). CD5L markedly promotes the proliferation and migration of endothelial cells.These molecules were co-enriched in pathways such as the “complement and coagulation cascade” and “prion disease,” suggesting a common mechanism of abnormal vascular permeability, inflammatory response, and microthrombosis. Disturbances in creatine metabolism suggested AMPK-related energy dysregulation, and the interaction between CD5L and microglia emphasized its neuroinflammatory regulatory function. This study revealing biomarkers and therapeutic targets, which provide new ideas for diagnosis and precise intervention. Supplementary Information The online version contains supplementary material available at 10.1038/s41598-026-40551-1.

Vascular endothelial growth factor (VEGF) is regarded as the essential promoter of vitreoretinal vascular diseases that threaten eyesight, such as proliferative diabetic retinopathy (PDR). Therefore, VEGF is the primary therapeutic target in these diseases, but not all patients respond adequately to VEGF inhibition. This raises the question if other factors contribute to disease modulation. PDR evolves in an interplay of pathological processes including inflammation, barrier integrity loss, aberrant angiogenesis, and metabolic dysregulation. Interleukin-6 (IL-6), recognized for its pro-inflammatory properties, was the focus of this study. Investigate IL-6 mediated angiogenic potential and disease-relevant mechanisms in the context of VEGF driven vitreoretinal disorder. Levels of IL-6 and soluble IL-6 receptor (sIL-6R) were quantified in patient samples using ELISA. In vitro, the functional effect and downstream signaling patterns of IL-6, sIL-6R and VEGF on vascular endothelial cells were analyzed with western blot, spheroid sprouting-, migration-, seahorse assays and LC–MS/MS. Vitreous samples from PDR patients showed elevated levels of IL-6 and its corresponding soluble IL-6 receptor (sIL-6R) compared to clinical control groups. In vitro, IL-6 trans-signaling (IL-6 + sIL-6R) leads to a pro angiogenic phenotype in human vascular endothelial cells demonstrated in migration and spheroid sprouting assays, mirroring the effects of VEGF. Interestingly, IL-6 trans- and VEGF-signaling differ in their effects on barrier integrity and metabolic profile. IL-6 trans-signaling disrupts endothelial barrier function and shows an increased mitochondrial oxygen consumption rate in the Seahorse assay, as well as lower produced lactate levels compared to VEGF. Tocilizumab, an IL-6R antibody, showed additive treatment effects to anti-VEGF therapeutics regarding angiogenesis and VEGF induced metabolic drive in vitro. IL-6 trans-signaling functions as an independent promoter of vitreoretinal vascular disease and therapeutic targeting of its pathway could beneficially complement current anti-VEGF treatment protocols.

Microvascular complications of diabetes include retinopathy (DR), diabetic kidney disease (DKD), and neuropathy (DN), which play a crucial role in diabetes management, as they significantly impair the functionality of the patient and remain major causes of morbidity despite advances in glycaemic control. The aim of this review was to summarize multi-omics findings in DR, DKD, and DN. Multi-omics studies consist of genomic, epigenomic, transcriptomic, proteomic, and metabolomic research. These studies provided comprehensive insights into the complex mechanisms underlying microvascular complications of diabetes, such as inflammation, angiogenesis, and apoptosis in the retina, kidneys, and nervous system. They also enabled the search for emerging diagnostic, prognostic, and therapeutic biomarkers. Moreover, changes in microRNA levels were found to differentiate patients with non-proliferative and proliferative DR. In addition, different proteins and metabolites concentrations were noticed in diabetes macular oedema and tractional retinal detachment—serious complications of DR. Specific molecular signatures, such as miR-146a and miR-27 dysregulation, changes in levels of HLA-DRA, AGER, and HSPA1A proteins, and alterations in tyrosine, alanine, 2,4-dihydroxybutanoic acid, ribonic acid, myoinositol, ribitol, 3,4-dihydroxybutanoic acid, valine, glycine, and 2-hydroxyisovaleric acid, were found to be characteristic for all microvascular complications of diabetes. In the future, more studies in multi-omics are expected to help improve precision medicine approaches to treating diabetes, allowing for personalized prediction, prevention, and treatment of microvascular complications.

Diabetic retinopathy (DR) is a leading cause of blindness, and ferroptosis may be an essential component of the pathological process of DR. In this study, we aimed to screen five hub genes (TLR4, CAV1, HMOX1, TP53, and IL-1B) using bioinformatics analysis and experimentally verify their expression and effects on ferroptosis and cell function. The online Gene Expression Omnibus microarray expression profiling datasets GSE60436 and GSE1025485 were selected for investigation. Ferroptosis-related genes that might be differentially expressed in DR were identified. Then, Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and protein-protein interaction (PPI) network analyses were conducted to characterize the differentially-expressed ferroptosis-related genes. After tissue-specific analyses and external dataset validation of hub genes, the mRNA and protein levels of hub genes in retinal microvascular endothelial cells (HRMECs) symbiotic with high glucose were verified using real-time quantitative PCR (qRT-PCR) and immunocytochemistry (ICC). Finally, hub genes were knocked down using siRNA, and changes in ferroptosis and cell function were observed. Based on the differential expression analysis, 19 ferroptosis-related genes were identified. GO and KEGG enrichment analyses showed that ferroptosis-related genes were significantly enriched in reactive oxygen species metabolic processes, necrotic cell death, hypoxia responses, iron ion responses, positive regulation of cell migration involved in sprouting angiogenesis, NF-kappa B signaling pathway, ferroptosis, fluid shear stress, and atherosclerosis. Subsequently, PPI network analysis and critical module construction were used to identify five hub genes. Based on bioinformatics analysis of mRNA microarrays, qRT-PCR confirmed higher mRNA expression of five genes in the DR model, and immunocytochemistry confirmed their higher protein expression. Finally, siRNA interference was used to verify the effects of five genes on ferroptosis and cell function. Based on bioinformatics analysis, five potential genes related to ferroptosis were identified, and their upregulation may affect the onset or progression of DR. This study sheds new light on the pathogenesis of DR.

Abstract Background Diabetic retinopathy (DR) is a significant complication of diabetes and the primary cause of blindness among working age adults globally. The development of DR is accompanied by oxidative stress, characterised by an overproduction of reactive oxygen species (ROS) and a compromised antioxidant system. Clinical interventions aimed at mitigating oxidative stress through ROS scavenging or elimination are currently available. Nevertheless, these treatments merely provide limited management over the advanced stage of the illness. Ferroptosis is a distinctive form of cell death induced by oxidative stress, which is characterised by irondependent phospholipid peroxidation. Purpose This review aims to synthesise recent experimental evidence to examine the involvement of ferroptosis in the pathological processes of DR, as well as to explicate the regulatory pathways governing oxidative stress and ferroptosis in retina. Methods We systematically reviewed literature available up to 2023. Results This review included 12 studies investigating the involvement of ferroptosis in DR. Graphical Abstract Schematic diagram of potential pathways leading to DR caused by ferroptosis. Characteristic manifestations of DR in the retina include haemorrhage, hard exudation, angiogenesis, and neurodegeneration. Iron accumulation, lipid peroxidation, and impaired antioxidant defence systems induced ferroptosis in diabetic retinopathy, resulting in compromised retinal cell viability, disrupted cell-to-cell junctions, and elicited inflammatory responses.

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. The expression of ferroptosis related genes in patients with proliferative diabetic retinopathy (PDR) and in diabetic mice was determined with RT-qPCR. Reactive oxygen species (ROS), 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 change of ferroptosis associated marker including GPX4, FTH1, ACSL4, TFRC and COX2 were detected in the retinal fibrovascular membrane of PDR patients, cultured HRMECs and the retina of diabetic mice. Elevated levels of ROS, lipid peroxidation and iron content were found in the retina of diabetic mice and also in cultured HRMECs. Ferroptosis was found to be associated with HRMECs 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.

Diabetic retinopathy (DR) is a common microvascular complication that causes visual impairment or loss. Aquaporin 4 (AQP4) is a regulatory protein involved in water transport and metabolism. In previous studies, we found that AQP4 is related to hypoxia injury in Muller cells. Transient receptor potential cation channel subfamily V member 4 (TRPV4) is a non-selective cation channel protein involved in the regulation of a variety of ophthalmic diseases. However, the effects of AQP4 and TRPV4 on ferroptosis and oxidative stress in high glucose (HG)-treated Muller cells are unclear. In this study, we investigated the functions of AQP4 and TRPV4 in DR. HG was used to treat mouse Muller cells. Reverse transcription quantitative polymerase chain reaction was used to measure AQP4 mRNA expression. Western blotting was used to detect the protein levels of AQP4, PTGS2, GPX4, and TRPV4. Cell count kit-8, flow cytometry, 5,5',6,6'-tetrachloro-1,1,3,3'-tetraethylbenzimidazolyl carbocyanine iodide staining, and glutathione (GSH), superoxide dismutase (SOD), and malondialdehyde (MDA) kits were used to evaluate the function of the Muller cells. Streptozotocin was used to induce DR in rats. Haematoxylin and eosin staining was performed to stain the retina of rats. GSH, SOD, and MDA detection kits, immunofluorescence, and flow cytometry assays were performed to study the function of AQP4 and TRPV4 in DR rats. Results found that AQP4 and TRPV4 were overexpressed in HG-induced Muller cells and streptozotocin-induced DR rats. AQP4 inhibition promoted proliferation and cell cycle progression, repressed cell apoptosis, ferroptosis, and oxidative stress, and alleviated retinal injury in DR rats. Mechanistically, AQP4 positively regulated TRPV4 expression. Overexpression of TRPV4 enhanced ferroptosis and oxidative stress in HG-treated Muller cells, and inhibition of TRPV4 had a protective effect on DR-induced retinal injury in rats. In conclusion, inhibition of AQP4 inhibits the ferroptosis and oxidative stress in Muller cells by downregulating TRPV4, which may be a potential target for DR therapy.

… Afterwards, hRMECs were treated with the ferroptosis-inducing agent … in ferroptosis. Erastin treatment reversed the impacts of PIM1 on hRMECs, suggesting the mediation of ferroptosis …

Introduction Diabetic retinopathy (DR) represents a prevalent and severe eye complication in diabetic patients. With DR progresses, destruction of tight junctions (TJs) in RPE cells leads to irreversible visual impairment. Gypenoside XLIX (Gyp XLIX) is a dammarane-type glycoside, which can suppress inflammation and oxidative stress. This study sought to investigate and verify the mechanism underlying the regulatory effects of Gyp XLIX in the early protection of junctional integrity of DR. Methods We combined bioinformatics and network pharmacology to pinpoint the core therapeutic targets of Gyp XLIX for DR. Mice with diabetes mellitus (DM) and high glucose (HG)-stimulated ARPE-19 cells were treated with Gyp XLIX. Its impact on TJ integrity in RPE cells and ferroptosis was evaluated via Western blotting, immunofluorescence staining, and assays for iron content, lipid peroxidation, and glutathione (GSH) levels. Prostaglandin-endoperoxide synthase 2 (PTGS2) was overexpressed to elucidate the mechanism of action of Gyp XLIX in the early protection of junctional integrity of DR. Results Among the shared targets between Gyp XLIX and DR, ALB, VEGFA, JUN, ESR1, PTGS2, STAT3, MMP9, HSP90AA1, BCL2L1 and AR were identified. Western blotting and immunofluorescence staining revealed that Gyp XLIX preserved TJ integrity in RPE cells. In addition, iron, lipid peroxidation and GSH assays revealed that Gyp XLIX inhibited ferroptosis in both mice with DM and HG-stimulated ARPE-19 cells. Overexpression of PTGS2 partially reversed the protective impacts induced by Gyp XLIX. Discussion This study demonstrated that Gyp XLIX suppressed ferroptosis and preserved TJ integrity in RPE cells, with these effects being closely associated with the downregulation of PTGS2, thereby exerting early protective effects on junctional integrity of DR.

Purpose This study aimed to measure the concentrations of ferroptosis-related biomarkers, namely, iron (Fe), lipid peroxide (LPO), reactive oxygen species (ROS), glutathione peroxidase-4 (GPX4), and glutathione (GSH) in DR in the attempt to evaluate the diagnostic performance of these biomarkers. Methods This study included 30 NPDR patients, 30 PDR patients, and 30 healthy subjects matched in age and sex. The concentrations of Fe, LPO, ROS, GPX4, and GSH in serum of the subjects were measured. Results Compared with the normal group, GPX4 and GSH concentrations were significantly lower, and LPO, Fe, and ROS concentrations were significantly higher in DR patients. Compared with the PDR group, the NPDR group had higher concentrations of LPO, Fe, and ROS and lower concentrations of GPX4 and GSH, but there was no statistical difference in Fe, GPX4, and GSH. ROC curve shows that ferroptosis-related biomarkers have accumulated accuracy in NPDR and PDR. Conclusion This study shows that ferroptosis-related biomarkers may be involved in the pathological process of DR and can be used as one of the biomarkers of DR.

Diabetic retinopathy (DR), characterized by vascular damage and chronic inflammation, poses a significant threat to vision. Programmed cell death (PCD) plays a crucial role in DR pathogenesis, with apoptosis, pyroptosis, and necroptosis being extensively implicated in retinal cell loss. Current research lacks a systematic analysis of the temporal dynamics of these PCD modalities. This review focuses on apoptosis, pyroptosis, and necroptosis to elucidate their stage-specific contributions to DR progression. Apoptosis primarily occurs in the nonproliferative DR (NPDR) phase and drives early microvascular lesions (e.g., microaneurysms and exudates) and neurodegeneration. Pyroptosis amplifies inflammation and is predominantly activated in the proliferative DR (PDR) phase, promoting pathological angiogenesis. Necroptosis may contribute to late-stage fibrosis, although its temporal role requires further validation. Other PCD pathways (e.g., ferroptosis, cuproptosis, and disulfidptosis) are briefly discussed as potential therapeutic targets. We propose a dynamic model in which caspase-mediated crosstalk between PCD pathways orchestrates DR progression. Targeting stage-specific PCD mechanisms offers promising strategies for intervention, yet challenges in clinical translation remain owing to cellular heterogeneity and pathway interdependencies.

ABSTRACT This study aims to explore the role of fatty acid binding protein 4 (FABP4) in diabetic retinopathy (DR), and to elucidate the potential regulatory mechanism. We firstly developed a mouse model of DR by injection with streptozocin (STZ) into C57BL/6 male mice and a cell model of DR by induction of high glucose (HG) to ARPE-19 cells. BMS309403, an inhibitor of FABP4, was employed for treatment. The blood glucose in vivo was monitored and the histological changes of retinal tissues were observed by hematoxylin and eosin staining and Evans blue assay. The expression level of FABP4 was detected by western blot and Immunohistochemical staining. The critical factors related to lipid peroxidation and oxidative stress were detected using their commercial kits, respectively. Prussian blue staining, iron content assay and thiobarbituric acid-reactive substances (TBARS) assay were conducted to evaluate ferroptosis. As a result, FABP4 was elevated in retina and serum of STZ-induced mice and in HG-induced ARPE-19 cells. BMS309403 treatment notably alleviated reduced blood glucose, reduced histological damage, and vascular permeability. In addition, BMS309403 treatment inhibited lipid peroxidation, oxidative stress, and ferroptosis both in vivo and in vitro. Furthermore, BMS309403 promoted the activation of peroxisome proliferator-activated receptor γ (PPARγ). GW9662 (an inhibitor of PPARγ) or Erastin (an inducer of ferroptosis) partially weakened the suppressive effects of BMS309403 on HG-induced lipid peroxidation, oxidative stress and ferroptosis. Taken together, FABP4 inhibition alleviates lipid peroxidation and oxidative stress in DR by regulating PPARγ-mediated ferroptosis. Graphical abstract

Diabetic retinopathy (DR), as one of the most common and significant microvascular complications of diabetes mellitus (DM), continues to elude effective targeted treatment for vision loss despite ongoing enrichment of the understanding of its pathogenic mechanisms from perspectives such as inflammation and oxidative stress. Recent studies have indicated that characteristic neuroglial degeneration induced by DM occurs before the onset of apparent microvascular lesions. In order to comprehensively grasp the early-stage pathological changes of DR, the retinal neurovascular unit (NVU) will become a crucial focal point for future research into the occurrence and progression of DR. Based on existing evidence, ferroptosis, a form of cell death regulated by processes like ferritinophagy and chaperone-mediated autophagy, mediates apoptosis in retinal NVU components, including pericytes and ganglion cells. Autophagy-dependent ferroptosis-related factors, including BECN1 and FABP4, may serve as both biomarkers for DR occurrence and development and potentially crucial targets for future effective DR treatments. The aforementioned findings present novel perspectives for comprehending the mechanisms underlying the early-stage pathological alterations in DR and open up innovative avenues for investigating supplementary therapeutic strategies.

Diabetic retinopathy (DR) is a microvascular lesion that occurs as a complication of diabetes mellitus. Many studies reveal that retinal neurodegeneration occurs early in its pathogenesis, and abnormal retinal function can occur in patients without any signs of microvascular abnormalities. The gut microbiota is a large, diverse colony of microorganisms that colonize the human intestine. Studies indicated that the gut microbiota is involved in the pathophysiological processes of DR and plays an important role in its development. On the one hand, numerous studies demonstrated the involvement of gut microbiota in retinal neurodegeneration. On the other hand, alterations in gut bacteria in RD patients can cause or exacerbate DR. The present review aims to underline the critical relationship between gut microbiota and DR. After a brief overview of the composition, function, and essential role of the gut microbiota in ocular health, and the review explores the concept of the gut-retina axis and the conditions of the gut-retina axis crosstalk. Because gut dysbiosis has been associated with DR, the review intends to determine changes in the gut microbiome in DR, the hypothesized mechanisms linking to the gut-retina axis, and its predictive potential.

To systematically evaluate the relationship between gut microbiota dysbiosis and diabetic retinopathy (DR), exploring microbial diversity, composition, metabolic function, and causal associations via the gut–eye axis. A systematic review and meta-analysis were conducted following PRISMA guidelines. Searches across PubMed, Scopus, Embase, and Web of Science identified studies examining gut microbiota in diabetic patients with and without DR. Eighteen eligible studies—including observational, cohort, and Mendelian randomization (MR) designs—were critically appraised. Meta-analyses pooled standardized mean differences (SMDs) for alpha diversity indices (Chao1, ACE, OTUs, Shannon, Simpson) between DR, diabetes without retinopathy (DM), and healthy controls (HC), using random-effects models with heterogeneity assessments. Gut microbiota in DR patients showed inconsistent alpha diversity changes but consistent beta diversity shifts, indicating distinct microbial community structures. Meta-analysis across eight studies (268 DR, 269 DM, 99 HC) revealed no significant differences in alpha diversity between DR and DM (e.g., Shannon SMD 0.01, 95% CI -0.44 to 0.45; I²=74%) or DR and HC (e.g., Shannon SMD 0.02, 95% CI -1.30 to 1.33; I²=71%), with moderate to high heterogeneity. DR cohorts exhibited altered Firmicutes/Bacteroidetes ratios, reduced short-chain fatty acid (SCFA)-producing genera (e.g., Faecalibacterium, Roseburia), and increased pro-inflammatory taxa (e.g., Escherichia-Shigella, Pseudomonas). Functional analyses revealed dysregulated amino acid and lipid metabolism, with specific taxa-metabolite correlations. This review substantiates gut microbiota dysbiosis as a potential contributor to DR pathogenesis via the gut–eye axis. While no robust changes in alpha diversity were found, compositional and functional alterations highlight specific microbial taxa and pathways as potential therapeutic targets. Microbiota modulation through diet, probiotics, or fecal transplantation may offer novel strategies to complement conventional DR management. However, high heterogeneity, demographic limitations, and methodological variations warrant further longitudinal and ethnically diverse studies to validate these findings and guide clinical translation.

Purpose Gut dysbiosis has been identified and tested in human trials for its role in diabetes mellitus (DM). The gut–retina axis could be a potential target for retardation of diabetic retinopathy (DR), a known complication of DM. This study reviews the evidence suggesting gut dysbiosis in DR. Methods The published literature in the past 5 years was reviewed using predetermined keywords and articles. The review intended to determine changes in gut microbiome in DR, the hypothesized mechanisms linking to the gut–retina axis, its predictive potential for progression of DR, and the possible therapeutic targets. Results The gut microbiota of people with DM differ from those without it, and the gut microbiota of people with DR differ from those without it. The difference is more significant in the former (DM versus no DM) and less significant in the latter (DM without DR versus DM with DR). Early research has suggested mechanisms of the gut–retina axis, but these are not different from known changes in the gut microbiome of people with DM. The current evidence on the predictive value of the gut microbiome in the occurrence and progression of DR is low. Therapeutic avenues targeting the gut–retina axis include lifestyle changes, pharmacologic inhibitors, probiotics, and fecal microbiota transplantation. Conclusions Investigating the therapeutic utility of the gut ecosystem for DM and its complications like DR is an emerging area of research. The gut–retina axis could be a target for retardation of DR but needs longitudinal regional studies adjusting for dietary habits.

… diabetic retinopathy (DR). Fecal microbiota transplantation confirmed microbial causality but revealed donor-dependent effects, and engineered Lactobacillus expressing angiotensin-…

Objective:To systematically investigate the shared and disease-specific mechanisms by which gut microbial metabolites may regulate age-related macular degeneration, diabetic retinopathy, and retinal vein occlusion through a network pharmacology framework.

The term microbiome means not only a complex ecosystem of microbial species that colonize our body but also their genome and the surrounding environment in which they live. Recent studies support the existence of a gut-retina axis involved in the pathogenesis of several chronic progressive ocular diseases, including age-related macular disorders. This review aims to underline the importance of the gut microbiome in relation to ocular health. After briefly introducing the characteristics of the gut microbiome in terms of composition and functions, the role of gut microbiome dysbiosis, in the development or progression of retinal diseases, is highlighted, focusing on the relationship between gut microbiome composition and retinal health based on the recently investigated gut-retina axis.

Introduction The objective of this study was to compare the microbiome in the aqueous humour and gut of people with diabetes mellitus (DM) with and without diabetic retinopathy (DR). Methods This was a prospective controlled study. The study included 17 people undergoing intraocular surgery in their naïve eyes. Stool samples were obtained in the perioperative period; aqueous humour samples of sufficient quantity were obtained in 12 people during intraocular surgery. Dietary information was obtained using a previously validated questionnaire. The gut and aqueous humour samples were assessed for microbiome using 16S rRNA gene sequencing coupled with QIIME and R software. Results Aqueous humour was analysed in 12 people: 4 each healthy controls, people with DM, and people with DR. There were minor differences at the phyla levels, but the aqueous humour microbiomes of healthy controls, DM, and DR formed three distinct clusters on heat map analysis with discriminatory genera. This genera-level clustering was more apparent for the intraocular than the gut microbiome. In people with DM and DR, we identified genera unique to the eye or the gut. There was a consistent reduction in the abundance of anti-inflammatory bacteria in people with DR than DM. Conclusions There is a difference in intraocular and gut microbiome regardless of disease or health. Our preliminary findings indicate distinctive features of the intraocular microbiome in people with DR compared with those without it. While this distinctiveness appears more evident in aqueous humour than in the gut, it needs further confirmation with larger studies.

The interplay between human microbiota and various physiological systems has garnered significant attention in recent years. The gut microbiota plays a critical role in maintaining physiological homeostasis and influences various aspects of human health, particularly via the gut brain axis. Since 2017, the challenging concept of the gut-retina axis has emerged thanks to a network analysis emphasizing the potential role of the gut microbiota disruption in the development of the age-related macular degeneration and further retinal damages. Many other ocular disorders have been linked to the dysbiosis of the gut microbiota, including uveitis and glaucoma. It has been shown that age related macular degeneration can be prevented or reversed using a diet that induces changes in the gut microbiota. The potential link between the gut microbiota as well as others types of microbiota such as the ocular surface microbiota and the development/progression of age related as well as inherited retinal degenerations and other degenerative eye diseases, has recently been broadened. Therefore, the pathogenesis of several eye diseases has recently been associated with a larger perception called the gut eye axis. This mini-review examines the potential mechanisms underlying the gut eye axis and suggests implications for the management of eye diseases. By understanding the modulation of the gut microbiota and its impact on eye disease, this mini-review provides insight into potential therapeutic interventions and avenues for future research.

The blood-retinal barrier (BRB) stringently restricts the delivery of dietary nutrients to retinal tissues, presenting a major bottleneck for targeted nutritional intervention. This review systematically delineates three core pathways through which food-derived bioactive compounds overcome the limited delivery efficiency of the BRB: transporter-mediated active transport across the barrier, biotransformation by gut microbiota and the liver into bioactive metabolites with superior bioavailability, and gut-retina axis-mediated remote regulation of retinal homeostasis. An innovative focus is placed on "nutrient synergy" strategies, detailing their mechanisms for enhancing retinal targeting: absorption enhancement using biomimetic or lipid-based carriers, steering biotransformation via prebiotic combinations, and modulating transporter expression to facilitate ocular uptake. This synthesis provides a forward-looking framework for the rational design of BRB-targeted nutritional schemes, paving the way for their integration with precision nutrition and advanced delivery systems to achieve effective and personalized visual health support.

Diabetic retinopathy (DR) is the most common and detrimental microvascular complication of diabetes mellitus. It has become one of the top causes of blindness and visual impairment in the working-age population. However, prevention and treatment options for DR are limited, invasive, and expensive, and most are focused on advanced-stage disease. The gut microbiota is an intricate system that alters the body's microenvironment, and its dysbiosis is strongly associated with DR. Recently, more and more investigations into the relationship between microbiota and DR have enhanced our understanding of how the gut microbiota influences the occurrence, development, prevention, and treatment of DR. In this review, we summarize the changes in the gut microbiota of animals and patients with DR and the function of metabolites and anti-diabetes drugs. Furthermore, we discuss the potential use of gut microbiota as an early diagnostic marker and targeting for DR in the healthy people and diabetic patients. Finally, the microbiota-gut-retina axis is presented to help us understand the mechanisms underlying the effect of gut microbiota on triggering or promoting DR, with a focus on the key pathways (e.g., bacterial dysbiosis and gut barrier dysfunction) that promote inflammation, insulin resistance, retinal cell and acellular capillary damage, leading to DR. Based on these data, we can hope to achieve a non-invasive, inexpensive treatment for DR by modulating the gut microbiota, either by supplementation with probiotics or by fecal transplantation. We outline the gut microbiota-targeting treatments in detail that could prevent DR progression.

To determine the association of gut microbiome diversity and sight-threatening diabetic retinopathy (STDR) amongst patients with pre-existing diabetes. A cross-sectional study was performed, wherein 54 participants selected in total were placed into cases cohort if diagnosed with STDR and those without STDR but had a diagnosis of diabetes mellitus of at least 10-year duration were taken as controls. Statistical analysis comparing the gut microbial alpha diversity between cases and control groups as well as patients differentiated based on previously hypothesized Bacteroidetes/Firmicutes(B/F) ratio with an optimal cut-off 1.05 to identify patients with STDR were performed. Comparing gut microbial alpha diversity did not show any difference between cases and control groups. However, statistically significant difference was noted amongst patients with B/F ratio ≥1.05 when compared to B/F ratio < 1.05; ACE index [Cut-off < 1.05:773.83 ± 362.73; Cut-off > 1.05:728.03 ± 227.37; p-0.016]; Chao1index [Cut-off < 1.05:773.63 ± 361.88; Cut-off > 1.05:728.13 ± 227.58; p-0.016]; Simpson index [Cut-off < 1.05:0.998 ± 0.001; Cut-off > 1.05:0.997 ± 0.001; p-0.006]; Shannon index [Cut-off < 1.05:6.37 ± 0.49; Cut-off > 1.05:6.10 ± 0.43; p-0.003]. Sub-group analysis showed that cases with B/F ratio ≥ 1.05, divided into proliferative diabetic retinopathy (PDR) and clinically significant macular edema (CSME), showed decreased diversity compared to controls (B/F ratio < 1.05). For PDR, all four diversity indices significantly decreased (p < 0.05). However, for CSME, only Shannon and Simpson indices showed significant decrease in diversity (p < 0.05). Based on clinical diagnosis, decreasing gut microbial diversity was observed among patients with STDR, although not statistically significant. When utilizing B/F ratio, the decreasing gut microbial diversity in STDR patients seems to be associated due to species richness and evenness in PDR when compared to decreasing species richness in CSME.

AIM To provide the direct evidence for the crucial role of trimethylamine N-oxide (TMAO) in vascular permeability and endothelial cell dysfunction under diabetic condition. METHODS The role of TMAO on the in vitro biological effect of human retinal microvascular endothelial cells (HRMEC) under high glucose conditions was tested by a cell counting kit, wound healing, a transwell and a tube formation assay. The inflammation-related gene expression affected by TMAO was tested by real-time polymerase chain reaction (RT-PCR). The expression of the cell junction was measured by Western blotting (WB) and immunofluorescence staining. In addition, two groups of rat models, diabetic and non-diabetic, were fed with normal or 0.1% TMAO for 16wk, and their plasma levels of TMAO, vascular endothelial growth factor (VEGF), interleukin (IL)-6 and tumor necrosis factor (TNF)-α were tested. The vascular permeability of rat retinas was measured using FITC-Dextran, and the expression of zonula occludens (ZO)-1 and claudin-5 in rat retinas was detected by WB or immunofluorescence staining. RESULTS TMAO administration significantly increased the cell proliferation, migration, and tube formation of primary HRMEC either in normal or high-glucose conditions. RT-PCR showed elevated inflammation-related gene expression of HRMEC under TMAO stimulation, while WB or immunofluorescence staining indicated decreased cell junction ZO-1 and occludin expression after high-glucose and TMAO treatment. Diabetic rats showed higher plasma levels of TMAO as well as retinal vascular leakage, which were even higher in TMAO-feeding diabetic rats. Furthermore, TMAO administration increased the rat plasma levels of VEGF, IL-6 and TNF-α while decreasing the retinal expression levels of ZO-1 and claudin-5. CONCLUSION TMAO enhances the proliferation, migration, and tube formation of HRMEC, as well as destroys their vascular integrity and tight connection. It also regulates the expression of VEGF, IL-6, and TNF-α.

Introduction Along with blood glucose levels, diabetic retinopathy (DR) development also involves endogenous risk factors, such as trimethylamine-N-oxide (TMAO), a product of intestinal flora metabolic disorder, which exacerbates diabetic microvascular complications. However, the effect of TMAO on retinal cells under high-glucose conditions remains unclear. Therefore, this study examined the effects of TMAO on high-glucose-induced retinal dysfunction in the context of NLRP3 inflammasome activation, which is involved in DR. Materials and Methods TMAO was assessed in the serum and aqueous humor of patients using ELISA. Human retinal microvascular endothelial cells (HRMECs) were treated for 72 h as follows: NG (normal glucose, D-glucose 5.5 mM), NG + TMAO (5 μM), HG (high glucose, D-glucose 30 mM), and HG + TMAO (5 μM). The CCK8 assay was then used to assess cell proliferation; wound healing, cell migration, and tube formation assays were used to verify changes in cell phenotype. ZO-1 expression was determined using immunofluorescence and western blotting. Reactive oxygen species (ROS) formation was assessed using DCFH-DA. NLRP3 inflammasome complex activation was determined using a western blot. Results The serum and aqueous humor from patients with PDR contained higher levels of TMAO compared to patients with nontype 2 diabetes (Control), non-DR (NDR), and non-PDR (NPDR). TMAO showed significant acceleration of high-glucose-induced cell proliferation, wound healing, cell migration, and tube formation. ZO-1 expression decreased remarkably with the combined action of TMAO and a high glucose compared to either treatment alone. TMAO also promoted high-glucose-activated NLRP3 inflammasome complex. Conclusion The combination of TMAO and high-glucose results in increased levels of ROS and NLRP3 inflammasome complex activation in HRMECs, leading to exacerbated retinal dysfunction and barrier failure. Thus, TMAO can accelerate PDR occurrence and development, thus indicating the need for early fundus monitoring in diabetic patients with intestinal flora disorders.

… pattern (PAMP), LPS activates innate immune responses by … of TMAO led to a decline in retinal ZO-1 and claudin-5 protein levels, along with elevated plasma concentrations of vascular …

Diabetic retinopathy, a prevalent microvascular complication of diabetes mellitus, is characterized by its increasing global prevalence and stands as the leading cause of visual impairment and blindness in adults. The pathogenesis of diabetic retinopathy involves multifactorial interactions, among which inflammatory responses play a pivotal role in disease progression. With the emergence of the "gut-retinal axis" concept, growing evidence has elucidated the intricate association between gut microbiota dysbiosis and the development of diabetic retinopathy. Studies have revealed significant differences in gut microbiota composition and diversity between patients with diabetic retinopathy and those without diabetic retinopathy. Dysbiosis of the gut microbiota compromises intestinal barrier integrity, thereby facilitating the translocation of intestinal metabolites into systemic circulation. This process may trigger the activation of systemic inflammatory responses, thus contributing to the pathogenesis and progression of diabetic retinopathy. This review examines the metabolic disturbances and systemic inflammatory responses induced by gut microbiota dysbiosis in diabetes, providing an in-depth analysis of how gut microbiota dysbiosis influences the inflammatory mechanisms underlying diabetic retinopathy. Furthermore, it summarizes the protective effects of anti-diabetic drugs on diabetic retinopathy by modulating the intestinal microenvironment, offering novel perspectives for the treatment of diabetic retinopathy.

The gut microbiome consists of more than thousand different microbes and their associated genes and microbial metabolites. It influences various host metabolic pathways and is therefore important for homeostasis. In recent years, its influence on health and disease was extensively researched. In case of a microbiome disequilibrium called dysbiosis, the gut microbiome is associated with several diseases. Consequent chronic inflammation may lead to or promote inflammatory bowel disease, obesity, diabetes mellitus, atherosclerosis, alcoholic and non-alcoholic liver disease, cirrhosis, hepatocellular carcinoma and other diseases. The pathogenesis of the three most common retinal vascular diseases, diabetic retinopathy, retinal vein and artery occlusion, may also be influenced by an altered microbiome and associated risk factors such as diabetes mellitus, atherosclerosis, hypertension and obesity. Direct cause-effect relationships remain less well understood. A potential prevention or treatment modality for these diseases could be targeting and modulating the individual's gut microbiome.

… NPDR, the early stage of DR, is featured by increased retinal blood vessel permeability … activator TMAO, further exploring alterations in the migratory capacity and vascular formation …

Diabetic microvascular complications are the most common and serious late-stage problems with diabetes patient, while existing antidiabetic treatments still have limited effects in preventing or reversing microvascular damage. Traditional Chinese Medicine (TCM) has been applied in clinical practice for centuries, showing excellent therapeutic effects in alleviating diabetic microvascular complications. Recently, the regulatory effects of gut microbiota, especially concepts such as the “gut-retina axis” and “gut-kidney axis” have been proposed and supported by accumulating experiment, which shows the importance of gut microbiota in microvascular injury. This review focuses on how TCM-gut microbiota interactions contribute to the prevention and treatment of diabetic microvascular complications, reviewing and organizing the latest evidence from experimental and clinical research. We further summarize current limitations in the field and discuss future direction to better uncover the mechanisms of TCM-microbiota interactions.

Background: Early neurovascular unit (NVU) impairment plays a critical role in the pathogenesis of diabetic retinopathy (DR), often preceding clinically detectable changes. Butyrate, a short-chain fatty acid (SCFA) derived from gut microbiota, has shown promising metabolic and anti-inflammatory effects. Methods: This study investigated the protective potential of oral butyrate supplementation in a mouse model of early type 2 diabetes mellitus (T2DM) induced by a high-fat diet and streptozotocin. Mice (C57BL/6J) received sodium butyrate (5 g/L in drinking water) for 12 weeks. Retinal NVU integrity was assessed using widefield swept-source optical coherence tomography angiography (WF SS-OCTA), alongside evaluations of systemic glucose and lipid metabolism, hepatic steatosis, visual function, and gut microbiota composition via 16S rRNA sequencing. Results: Butyrate supplementation significantly reduced body weight, fasting glucose, serum cholesterol, and hepatic lipid accumulation. Microbiome analysis demonstrated a partial reversal of gut dysbiosis, characterized by increased SCFA-producing taxa (Ruminococcaceae, Oscillibacter, Lachnospiraceae) and decreased pro-inflammatory, lipid-metabolism-related genera (Rikenella, Ileibacterium). KEGG pathway analysis further revealed enrichment in microbial lipid metabolism functions (fabG, ABC.CD.A, and transketolase). Retinal vascular and neurodegenerative alterations—including reduced vessel density and retinal thinning—were markedly attenuated by butyrate, as revealed by WF SS-OCTA. OKN testing indicated partial improvement in visual function, despite unchanged ERG amplitudes. Conclusions: Butyrate supplementation mitigates early NVU damage in the diabetic retina by improving glucose and lipid metabolism and partially restoring gut microbial balance. This study also underscores the utility of WF SS-OCTA as a powerful noninvasive tool for detecting early neurovascular changes in DR.

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and a leading cause of vision impairment and blindness, which lacks effective diagnostic measures and therapeutic options. Sophora flavescens Aiton or "Kushen" is a traditional Chinese medicine used since ancient times, either alone or in combination, to clear heat, dampness, and tearing, and to treat ocular diseases and improve eyesight. Additionally, the flavonoids of Sophora flavescens Aiton extracted using ethyl acetate (EtOAc) (SFE) is effective in managing diabetes and diabetic vascular complications. In this study, we explored the pharmacodynamic effects and material basis of action of SFE on DR for the first time and elucidated the mechanism based on untargeted retinal metabolomics. Results from the pharmacodynamic studies showed that SFE could reduce blood glucose levels in rats, regulate serum lipopolysaccharide, tauroursodeoxycholic acid, and trimethylamine oxide levels, and significantly improve the structure of retina in rats with DR. Moreover, SFE could protect the blood-retinal barrier, reduce angiogenesis and capillary formation, and inhibit retinal nerve cell apoptosis. A total of 13 compounds were identified in the aqueous humor and retina, which were dihydroflavonoid, isoflavonoid, pterostane flavonoid, chalcone, and dihydroflavonol derivatives. In addition, 39 differential metabolites were screened based on retinal metabolomics data and 23 were found to be affected by SFE, indicating its anti-DR effect by regulating the synthetic metabolic pathways, including lactose, bile acid, glycerophospholipid, arginine, purine, and pyrimidine metabolism pathways. Collectively, our findings elucidated the effects, material basis, and treatment mechanism of SFE on DR systematically and could lay the foundation for promoting the clinical application of Sophora flavescens Aiton.

Type 2 diabetes mellitus (T2DM) and T2DM-related complications [such as retinopathy, nephropathy, and cardiovascular diseases (CVDs)] are the most prevalent metabolic diseases. Intriguingly, overwhelming findings have shown a strong association of the gut microbiome with the etiology of these diseases, including the role of aberrant gut bacterial metabolites, increased intestinal permeability, and pathogenic immune function affecting host metabolism. Thus, deciphering the specific microbiota, metabolites, and the related mechanisms to T2DM-related complications by combined analyses of metagenomics and metabolomics data can lead to an innovative strategy for the treatment of these diseases. Accordingly, this review highlights the advanced knowledge about the characteristics of the gut microbiota in T2DM-related complications and how it can be associated with the pathogenesis of these diseases. Also, recent studies providing a new perspective on microbiota-targeted therapies are included.

In this review, we aim to provide an overview of the recent findings about the treatment of neovascular retinal diseases. The use of conventional drugs and nutraceuticals endowed with antioxidant and anti-inflammatory properties that may support conventional therapies will be considered, with the final aim of achieving risk reduction (prevention) and outcome improvement (cooperation between treatments) of such sight-threatening proliferative retinopathies. For this purpose, we consider a medicinal product one that contains well-defined compound(s) with proven pharmacological and therapeutic effects, usually given for the treatment of full-blown diseases. Rarely are prescription drugs given for preventive purposes. A dietary supplement refers to a compound (often an extract or a mixture) used in the prevention or co-adjuvant treatment of a given pathology. However, it must be kept in mind that drug–supplement interactions may exist and might affect the efficacy of certain drug treatments. Moreover, the distinction between medicinal products and dietary supplements is not always straightforward. For instance, melatonin is formulated as a medicinal product for the treatment of sleep and behavioral problems; at low doses (usually below 1 mg), it is considered a nutraceutical, while at higher doses, it is sold as a psychotropic drug. Despite their lower status with respect to drugs, increasing evidence supports the notion of the beneficial effects of dietary supplements on proliferative retinopathies, a major cause of vision loss in the elderly. Therefore, we believe that, on a patient-by-patient basis, the administration of nutraceuticals, either alone or in association, could benefit many patients, delaying the progression of their disease and likely improving the efficacy of pharmaceutical drugs.

Interindividual variability in drug efficacy and toxicity remains a major challenge in clinical pharmacotherapy. Although pharmacogenomics has substantially advanced personalized medicine, host genetic variation alone cannot fully explain differences in drug disposition, response, and adverse effects. Increasing evidence identifies the human gut microbiota as an additional, functionally relevant metabolic layer that complements host drug-metabolizing enzymes, giving rise to the field of pharmacomicrobiomics. This discipline examines bidirectional interactions between drugs and microbial communities that influence absorption, metabolism, enterohepatic circulation, and pharmacodynamic outcomes. The gut microbiota can directly biotransform or sequester drugs through diverse enzymatic reactions, including deconjugation, reduction, and decarboxylation, thereby modifying systemic drug exposure and toxicity. In parallel, microbially derived metabolites and bile acid-mediated signaling pathways regulate host drug-metabolizing enzymes and transporters, including cytochrome P450 enzymes and ATP-binding cassette transporters. Conversely, many common medications-including antibiotics, chemotherapeutics, psychotropics, and proton pump inhibitors-can reshape microbial composition and function, causing dysbiosis that affects drug metabolism and therapeutic outcomes. This review summarizes the mechanistic basis and clinical relevance of microbiota-drug interactions across key therapeutic areas, including oncology, neuropsychiatric disorders, and metabolic diseases. Well-established examples, including microbial β-glucuronidase-mediated reactivation of irinotecan, microbiota-dependent modulation of levodopa and antidepressant pharmacokinetics, and microbiota-driven variability in immune checkpoint inhibitor efficacy, are discussed to illustrate causality. Emerging microbiome-informed strategies-including selective inhibition of microbial enzymes, microbiota modulation, and biomarker-based stratification-are highlighted. Finally, we examine integration of pharmacomicrobiomics with pharmacogenomics within multi-omic and systems pharmacology frameworks, emphasizing implications for predictive modeling and precision drug metabolism.

Type 2 diabetes mellitus is a systemic metabolic disorder with an extensive spectrum of complications, which still persist despite improvements in glycemic control. Emerging evidence suggests that gut dysbiosis may be an underpinning factor in the pathogenesis of both microvascular and macrovascular complications associated with diabetes. This narrative review explores the relationship between gut microbiota and the development of diabetes complications, including nephropathy, retinopathy, neuropathy, cardiovascular, cerebrovascular, peripheral vascular, and reproductive system disorders. First, existing evidence regarding the nature of shared and organ-specific microbial patterns is summarized. Next, key mechanistic pathways of inflammation and metabolism underlying tissue damage induced by dysbiosis are illustrated. Lastly, the role of gut microbiota and inflammaging as modifiers of these processes is described. Emerging clinical and translational implications are finally discussed, underscoring the promises of microbiota-based diagnostics as well as therapeutics that could serve as add-on approaches to the management of diabetic complications, alongside the application of artificial intelligence-based approaches to microbiome data analysis which may enhance biomarker discovery and risk stratification. Overall, although most evidence remains associative, increasing data support that gut microbiota dysbiosis may represent a potential disease modifier in the development of various diabetic complications. Further longitudinal and mechanistic studies are needed to clarify causality and to evaluate the clinical utility of microbiome-targeted interventions, including AI-assisted predictive models, in preventing or mitigating diabetic complications.