Curcumol targets the FTO/MAFG-AS1 axis to alleviate diabetic retinopathy via epigenetic remodeling and nanodelivery-based microenvironment modulation

Abstract

Diabetic retinopathy (DR) is a major microvascular complication of diabetes, with its pathogenesis involving metabolic memory, epigenetic dysregulation, and multi-cellular microenvironmental disorders. This study systematically investigates the mechanism by which curcumol ameliorates DR through regulation of the FTO/MAFG-AS1 epigenetic axis and reveals its therapeutic potential in targeting the retinal microenvironment via a nano-delivery system. Experimental results demonstrate that curcumol activates the demethylase activity of FTO, stabilizing the expression of the long non-coding RNA MAFG-AS1, thereby inhibiting high glucose-induced retinal endothelial cell inflammation, migration, and vascular leakage. Single-cell transcriptomic analysis further uncovered the dual role of FTO in DR: On the one hand, it promotes pathological angiogenesis in endothelial cells, while on the other hand, it exerts protective effects through MAFG-AS1-mediated antioxidative and anti-inflammatory functions. Moreover, this study proposes a multidimensional epigenetic regulatory network based on histone lactylation, N6-methyladenosine modification, and DNA methylation, and verifies that curcumol delays DR progression by coordinately modulating these modifications. To overcome the limitations of conventional therapies, this study innovatively designed a macrophage membrane-coated nano-delivery system, significantly enhancing the retinal targeting and bioavailability of curcumol. Finally, the study advocates a paradigm shift from passive treatment to early prevention, proposing a three-tiered intervention strategy that integrates epigenetic biomarkers with artificial intelligence-based risk assessment. These findings not only elucidate the multi-target regulatory mechanisms of curcumol but also provide a theoretical foundation for the development of precision therapies for DR based on epigenetic remodeling and microenvironmental synergistic intervention.

Key Words: Curcumol; Diabetic retinopathy; Epigenetic regulation; FTO/MAFG-AS1 pathway; N6-methyladenosine modification; Metabolic memory; Nano-delivery system; Single-cell transcriptomics

Core Tip: This study reveals curcumol's dual-action mechanism in diabetic retinopathy through FTO/MAFG-AS1 axis modulation and macrophage membrane-coated nanodelivery. Curcumol activates FTO demethylase to stabilize MAFG-AS1, suppressing hyperglycemia-induced vascular leakage and inflammation. Single-cell transcriptomics resolve FTO's paradoxical roles: Promoting pathological angiogenesis in endothelial cells while exerting antioxidant/anti-inflammatory effects via MAFG-AS1. A multidimensional epigenetic network integrates N6-methyladenosine, histone lactylation, and DNA methylation. Biomimetic nanoparticles enhance retinal targeting and bioavailability. The paradigm shifts from reactive treatment to artificial intelligence-guided prevention, emphasizing early intervention via metabolic memory disruption and multi-tiered clinical strategies. These findings advance precision therapy by synergizing epigenetics, nanotechnology, and systems biology.

TO THE EDITOR

I read with great interest the recently published article "Curcumol ameliorates diabetic retinopathy (DR) via modulating fat mass and obesity-associated protein-demethylated MAF transcription factor G antisense RNA 1" by Rong et al[1] in your esteemed journal. This study reveals a novel signaling pathway, namely, the demethylation of MAFG-AS1 by FTO, elucidating the potential mechanism of curcumol in the treatment of DR.

DR, as one of the most common microvascular complications of diabetes, is a leading cause of vision impairment and blindness among adults with diabetes worldwide. Epidemiological data indicate that approximately 24.7%-37.5% of diabetic patients suffer from DR, and with the continued rise in diabetes prevalence (projected to reach 783 million globally by 2045), the disease burden of DR is expected to further escalate[2,3]. Although current therapies, such as anti-vascular endothelial growth factor (VEGF) drugs and laser treatment, can slow disease progression, their efficacy remains limited, and there is a risk of recurrence. Moreover, some patients experience adverse effects such as retinal fibrosis due to drug resistance or invasive procedures. Therefore, exploring non-invasive therapeutic strategies targeting novel molecular pathways has become an urgent research priority[3].

In recent years, natural products have attracted significant attention in the treatment of metabolic diseases due to their multi-target regulatory effects and low toxicity. Curcumol, an active component derived from Zingiberaceae plants, has been demonstrated to exert anti-inflammatory, antioxidant, and anti-fibrotic effects, showing potential in complications such as diabetic nephropathy and non-alcoholic fatty liver disease. However, its precise mechanism in DR remains unclear, particularly its regulatory effects on the epigenetic network, which have yet to be elucidated[1].

Notably, non-coding RNAs [e.g., long non-coding RNAs (lncRNAs)] and RNA epigenetic modifications [e.g., N6-methyladenosine (m6A)] have emerged as frontier topics in metabolic disease research[4]. Studies have shown that m6A modification participates in diabetes-related vascular lesions by regulating RNA stability, localization, and translation, while lncRNAs can modulate inflammation and angiogenesis through chromatin remodeling or competitive binding with microRNAs (miRNAs). For instance, MAFG-AS1, a newly identified oncogenic lncRNA, regulates gene expression via m6A modification in hepatocellular carcinoma and colorectal cancer; however, its role in DR remains unexplored[1,5].

Against this background, the study by Rong et al[1] is the first to reveal the molecular mechanism by which curcumol ameliorates DR through the FTO/MAFG-AS1 axis, filling a knowledge gap at the intersection of natural products and epigenetic regulation. Through in vivo and in vitro experiments, the study demonstrated that curcumol not only significantly alleviates retinal damage in diabetic mice but also inhibits high glucose-induced endothelial inflammation and migration via FTO-mediated MAFG-AS1 demethylation[1].

This discovery not only expands the pharmacological profile of curcumol but also provides an innovative RNA epigenetic modification-based target for DR treatment. However, translating such fundamental research findings into clinical practice requires further validation of its applicability in different diabetes models (e.g., type 2 diabetes) and exploration of its synergistic effects with other therapies.

Epigenetic regulation: Beyond the traditional pharmacological paradigm

The most striking innovation of this study is the integration of traditional Chinese medicinal active components with modern epigenetic mechanisms. However, focusing solely on m6A modifications might oversimplify the complexity involved. DR, as a multifaceted pathological process, also involves multilayered epigenetic regulatory networks, including histone modifications and DNA methylation (Table 1).

Table 1 Main molecular targets and mechanisms of action of curcumol.

Molecular target	Normal function	Changes in DR	Regulatory effect of curcumol	Downstream pathological impact	Ref.
FTO protein	m6A demethylase; regulates RNA stability and expression	Abnormal expression under high-glucose conditions; significantly elevated in fibrovascular vitreous membranes of proliferative DR patients	Increases FTO expression, activating its demethylase activity	Stabilizes MAFG-AS1 expression, inhibits endothelial inflammation and vascular leakage	Rong et al[1]
MAFG-AS1	Long non-coding RNA involved in metabolism and inflammation regulation	Increased m6A modification and decreased stability under high-glucose conditions	Stabilizes MAFG-AS1 through FTO-mediated demethylation	Suppresses high glucose-induced endothelial proliferation, migration, and inflammation	Rong et al[1]
Histone lactylation	Epigenetic modification regulating gene expression	Lactate-mediated histone lactylation upregulates FTO expression	Possibly indirectly regulates FTO expression via modulation of histone lactylation	Forms a more complex epigenetic regulatory network, influencing retinal vascular integrity	Chen et al[6]
Inflammatory cytokines	Mediate immune responses and tissue repair	Elevated pro-inflammatory cytokines (TNF-α, IL-6), triggering chronic inflammation	Downregulates IκBα, cyclooxygenase-2, prostaglandin E2, and multiple interleukins	Reduces retinal inflammation, protecting retinal neurons and vascular function	Franzone et al[50]
Blood-retinal barrier components	Maintain homeostasis in the retinal microenvironment	Reduced cadherin and tight junction protein ZO-1 expression, impairing barrier function	Restores endothelial-specific cadherin and ZO-1 expression	Reduces vascular leakage, protecting retinal neurons from damage	Chen et al[6]

DR: Diabetic retinopathy; IL-6: Interleukin-6; m6A: N6-methyladenosine; TNF-α: Tumor necrosis factor-alpha; ZO-1: Zonula occludens-1.

Recent studies have uncovered a novel epigenetic regulatory pathway: Lactylation-driven regulation of FTO plays a critical role in DR. Chen et al[6] demonstrated significantly elevated FTO expression in the fibrovascular vitreous membranes of patients with proliferative DR. FTO not only promotes endothelial cell cycle progression and tip cell formation, thereby enhancing pathological angiogenesis, but also regulates endothelial-pericyte interactions, triggering diabetic microvascular leakage. Additionally, FTO mediates endothelial-microglial interactions, contributing to retinal inflammation and neurodegenerative changes[6]. Importantly, lactate-mediated histone lactylation was identified as a key driver of FTO upregulation under diabetic conditions, suggesting that curcumol may indirectly regulate FTO expression through histone lactylation, forming an even more intricate epigenetic regulatory network[6].

Tang et al[7] further revealed the interactions among multiple epigenetic modifications in DR. Their findings indicate that beyond m6A, other RNA methylation forms, such as m5C and m1A, also contribute to DR pathogenesis. Under hyperglycemic conditions, METTL3 expression decreases, and its catalyzed m6A modification stabilizes lncRNA SNHG7, inhibiting endothelial-to-mesenchymal transition. This highlights the complex interplay between various RNA epigenetic modifications and non-coding RNAs. Concurrently, DNA methylation, another crucial epigenetic modification, also significantly contributes to DR pathogenesis. Bhamidipati et al[8] identified 46 genes with CpG island methylation markers in proliferative retinopathy, finding that hypomethylation in the promoter region of the MAP3K1 pathway correlates with its upregulation, thereby promoting disease progression.

These discoveries imply that curcumin might exert therapeutic effects through synergistically regulating multiple epigenetic modifications, not limited merely to the single FTO/MAFG-AS1 pathway. Liu et al[9] noted that epigenetics describes changes in gene expression and function without alterations in DNA sequences, resulting in heritable phenotypes. This mechanism plays an essential role in DR initiation, progression, and sustained complications. Similarly, curcumin, another active component from Zingiberaceae plants, has been demonstrated to significantly inhibit diabetes-induced retinal oxidative stress and inflammation by modulating the expression of various epigenetic-modifying enzymes and inflammatory factors (such as tumor necrosis factor-alpha)[10].

Future research should consider constructing multidimensional epigenomic atlases that integrate genomic, transcriptomic, proteomic, and metabolomic data to comprehensively elucidate the regulatory mechanisms of active ingredients in traditional Chinese medicine. Kwak et al[11] proposed that therapies based on epigenetic mechanisms might represent a novel direction for targeted DR treatment. In particular, it is critical to explore how curcumin simultaneously influences DNA methylation, histone lactylation, and RNA methylation, and their complex interaction networks with non-coding RNAs. Additionally, spatial transcriptomics and proteomics analyses at single-cell resolution could reveal the heterogeneity of epigenetic modifications across different retinal cell types, providing a new theoretical and technological foundation for precision interventions in DR.

The contradictory role of FTO in DR

This study found that FTO exerts a protective effect by demethylating MAFG-AS1, which contrasts notably with recent findings. Studies have shown[6] that, "FTO promotes endothelial cell cycle progression and tip cell formation, thus enhancing angiogenesis in DR", suggesting that FTO may exacerbate microvascular dysfunction. This contradictory phenomenon indicates that FTO may play distinctly different roles in various cell types and at different disease stages. I propose that this "double-edged sword" effect needs to be analyzed through spatial transcriptomics at single-cell resolution to define tissue- and cell-specific regulatory networks, thereby providing a foundation for precision therapy (Table 2).

Table 2 Cell type-specific effects within the retinal microenvironment.

Cell type	Normal function	Pathological changes in DR	Interaction with other cells	Response to curcumol	Therapeutic significance
Retinal vascular endothelial cells	Maintain blood-retinal barrier, regulate vascular permeability	Abnormal proliferation, increased migration, decreased tight junction proteins	Reduced interaction with pericytes, enhanced interaction with microglia	Inhibits proliferation and migration, restores tight junction protein expression	Primary therapeutic target; improves vascular function, reduces leakage
Pericytes	Maintain capillary stability, regulate blood flow	Reduced number, impaired function, decreased contact with endothelial cells	Disrupted communication with endothelial cells, causing vascular instability	Improves pericyte-endothelial interaction, stabilizes microvascular structure	Protective therapeutic target; preventing pericyte loss is critical
Microglia	Immune surveillance, neuroprotection, synaptic pruning	Increased activation, morphological changes, elevated Iba-1 expression	Release inflammatory cytokines affecting endothelial cells and neurons	Suppresses activation, reduces neuroinflammation, protects neuronal function	Emerging therapeutic target; modulates neuroinflammation
Müller glial cells	Structural support, ion homeostasis, metabolic support	Activation, increased GFAP expression, release of VEGF and inflammatory cytokines	Metabolic support for all retinal cell types	Attenuates glial activation, reduces VEGF expression	Important regulatory target; maintains overall retinal homeostasis
Retinal ganglion cells	Visual signal transmission, visual information integration	Dysfunction, axonal degeneration, increased apoptosis	Affected by microglial inflammation and Müller cell dysfunction	Reduces oxidative stress damage, protects neuronal survival	Neuroprotective target; prevents irreversible vision loss
Retinal pigment epithelium	Outer blood-retinal barrier, supports photoreceptors	Barrier impairment, pigmentary changes, lipid deposition	Interacts with photoreceptors and choroidal vessels	Enhances antioxidant capacity, maintains epithelial integrity	Adjunct therapeutic target; preserves overall retinal function

DR: Diabetic retinopathy; GFAP: Glial fibrillary acidic protein; Iba-1: Ionized calcium-binding adapter molecule 1; VEGF: Vascular endothelial growth factor.

The multifaceted roles and therapeutic potential of FTO in DR

FTO plays multiple cell type-specific roles in DR. In endothelial cells, FTO regulates the stability of CDK2 mRNA via an m6A-YTHDF2–dependent mechanism, thereby promoting cell cycle progression and tip cell formation, ultimately enhancing pathological angiogenesis. This process is driven by lactate-mediated histone lactylation, revealing a direct link between metabolic alterations and epigenetic regulation[6]. Chen et al[6] found that FTO expression is significantly elevated in the epiretinal fibrovascular membranes of patients with proliferative DR, and that the FTO inhibitor FB23-2 effectively suppresses angiogenic phenotypes, indicating its potential therapeutic value.

In contrast, FTO exhibits a protective role in retinal pigment epithelial (RPE) cells by upregulating MAFG-AS1 expression[12]. Studies show that under hyperglycemic conditions, treatment with carvacrol induces FTO expression, which in turn stabilizes MAFG-AS1 via demethylation, thereby inhibiting high glucose-induced inflammation, cell migration, and vascular leakage. SRAMP prediction indicates that MAFG-AS1 transcripts contain multiple m6A modification sites, and FTO expression is closely associated with its stability[1,6].

Moreover, FTO participates in inflammatory regulation in macrophages/microglia through multiple signaling pathways. Inhibition of FTO can suppress NLRP3 inflammasome activation via the FoxO1/NF-κB pathway, alleviating tissue damage. Simultaneously, through a Prrc2a-dependent mechanism, it reduces the m6A modification of NPAS2 and modulates the HIF-1α signaling pathway, thereby inhibiting the inflammatory response and glycolysis of M1 macrophages[1,13]. Collectively, these studies highlight the crucial regulatory role of FTO in DR pathogenesis and underscore its potential as a therapeutic target.

Dual functional mechanisms and regulatory characteristics of FTO in early and late stages of DR

FTO exhibits dynamic and dual regulatory roles at different stages of DR. In the early stages (mild and moderate non-proliferative DR), retinal neurodegeneration precedes vascular abnormalities. During this phase, FTO may exert neuroprotective effects by modulating glial-neuronal interactions and neuroinflammation. Previous studies have shown that FTO, through regulation of MAFG-AS1, contributes to antioxidant and anti-inflammatory mechanisms, thus offering some degree of retinal protection.

As DR progresses into the late stages (severe non-proliferative and proliferative DR), FTO's function shifts significantly toward promoting pathological angiogenesis[1]. Chen et al[6] confirmed that in the fibrovascular membranes of proliferative DR patients, FTO expression is markedly increased. It accelerates endothelial cell cycle progression, promotes tip cell formation, and disrupts endothelial–pericyte interactions, thereby inducing microvascular leakage and exacerbating retinal damage.

This stage-dependent shift may be attributed to the target specificity and subcellular localization differences of FTO in distinct cellular contexts. Under pathological conditions, FTO mainly demethylates CDK2 mRNA to promote abnormal vascular growth, while under protective conditions, it targets MAFG-AS1 to exert anti-inflammatory effects. Additionally, FTO primarily targets m6Am in the cytoplasm, whereas in the nucleus, it acts on m6A modifications in mRNA and snRNA-highlighting its functional diversity based on localization. FTO also acts through various signaling pathways, such as promoting angiogenesis via the m6A-YTHDF2 pathway in endothelial cells, while activating protective regulatory pathways in other contexts[14].

These findings reveal the complex mechanisms of FTO’s role throughout DR progression and provide a theoretical basis for stage-specific therapeutic interventions.

Achieving precise understanding through advanced technologies

Single-cell RNA sequencing (scRNA-seq) has revolutionized our cell-level understanding of retinal gene expression. Combined with spatial transcriptomic approaches such as MERFISH, these techniques enable us to map specific retinal cell types and their functional associations[15].

Integrative analyses using scRNA-seq and transcriptomics have uncovered novel aspects of DR pathogenesis, including alternative transcriptional events, changes in cellular composition, and key signaling pathways[15,16]. When combined with genetic association studies and multi-omics analyses, these approaches have identified biomarkers, susceptibility genes, and therapeutic targets for DR, highlighting the roles of specific retinal cell types in disease progression[16,17].

Spatial transcriptomics allows simultaneous investigation of gene expression and cell location. A recent MERFISH study created a single-cell spatial atlas of the mouse retina, analyzing over 390000 cells and identifying all major cell types and subtypes. This atlas revealed eight previously unknown displaced amacrine cell subtypes and linked molecular classification to spatial arrangement. The technology also identified location-dependent differential gene expression among subtypes, suggesting location-based functional regulation[18].

Applying these technologies to study FTO in DR will enable precise mapping of FTO expression across different retinal cell types and disease stages. This approach may resolve contradictions by distinguishing cell-specific roles and determining the conditions under which FTO functions as protective or pathological.

The dual role of FTO in DR therapy and future therapeutic strategies

The dual nature of FTO in DR has significant implications for therapeutic strategies. Current treatments targeting FTO have shown promise, highlighting its complex roles in the pathogenesis of DR.

FB23-2, an inhibitor of FTO's m6A demethylase activity, suppresses angiogenic phenotypes in vitro. Researchers developed a macrophage membrane-coated poly (lactic-co-glycolic acid) (PLGA) nanoparticle platform encapsulating FB23-2 for systemic delivery, enhancing endothelial cell uptake and targeting retinal neovascularization. This method effectively increased m6A levels and inhibited retinal neovascularization in mice, indicating its potential clinical value[6].

Conversely, under specific circumstances, enhancing FTO activity may confer therapeutic benefits. Curcumin increases FTO expression under high-glucose conditions and exerts protective effects in DR by regulating the FTO/MAFG-AS1 axis, thereby reducing retinal damage, inflammation, and vascular dysfunction in diabetic mice[1].

These contradictory therapeutic approaches underscore the necessity of precision medicine in treating DR. Future treatments may require targeting specific cell types or molecular pathways influenced by FTO through cell-specific delivery systems, timed drug release, or combination therapies.

COMPLEXITY OF THE LNCRNA REGULATORY NETWORK

This study identifies MAFG-AS1 as a critical downstream effector but overlooks its role within a broader lncRNA regulatory network. Recent studies indicate the existence of a complex non-coding RNA regulatory network in DR, rather than the actions of a single lncRNA alone. Transcriptomic analyses by Sharma et al[19] of retinal tissues and serum samples from DR patients revealed abnormal expression of multiple lncRNAs (e.g., MALAT1, HOTAIR, ANRIL, and AQP4-AS1) in DR. In particular, HOTAIR expression is significantly increased in diabetic retinas and retinal endothelial cells stimulated by high glucose. Knockdown of HOTAIR inhibits proliferation, invasion, migration, and permeability of high glucose-stimulated retinal endothelial cells, and reduces acellular capillaries and vascular leakage in diabetic retinas[20].

Adding to the complexity, some studies demonstrated that these lncRNAs collectively form a sophisticated competing endogenous RNA (ceRNA) network, influencing the expression of miRNAs and their target genes through competitive binding with miRNAs[21,22]. For example, MIAT, which is upregulated in DR, can regulate VEGF expression by competitively binding miR-150-5p, thereby promoting angiogenesis[23]. Similarly, ANRIL promotes retinal endothelial cell proliferation and tube formation by sponging miR-200b, resulting in the upregulation of VEGF[24,25]. Recent studies suggest that MAFG-AS1 may affect CTNNB1 expression through interaction with miR-424-5p, subsequently influencing the Wnt/β-catenin signaling pathway, a crucial pathway in DR pathogenesis.

Previous research has also shown that lncRNAs regulate gene expression through multiple mechanisms, including epigenetic modifications (such as histone methylation and phosphorylation), transcriptional regulation, RNA splicing, and translational control[6,26,27]. For instance, ANRIL regulates histone modifications of target genes by recruiting the PRC2 complex, while MALAT1 primarily affects RNA splicing through modulating the phosphorylation of SR proteins. These multi-level regulatory mechanisms further enhance the complexity of the lncRNA network[28].

Given this complexity, simply targeting individual lncRNAs may be insufficient for optimal therapeutic outcomes. Researchers have proposed constructing comprehensive lncRNA-miRNA-mRNA regulatory networks to deeply explore how MAFG-AS1 collaborates with other non-coding RNAs[29,30]. This approach integrates technologies such as RNA-seq, MeRIP-seq, RNA pull-down, and CLIP-seq to comprehensively analyze the expression profiles, modification states, interacting proteins, and binding targets of lncRNAs[29,31,32]. Network models built upon these foundations could provide a theoretical basis for developing RNA-network-targeted therapeutic strategies for DR.

PARADIGM SHIFT FROM PASSIVE TREATMENT TO ACTIVE PREVENTION

This study positions curcumin as a therapeutic agent for established DR, rather than as a preventive intervention. Given the irreversible nature of DR, research directions should shift from passive treatment toward a "preventive medicine" paradigm. DR is the leading cause of irreversible blindness among the working-age population, making prevention essential for preserving patients' visual function. Epidemiological data indicate that the global prevalence of DR ranges from 24.7% to 37.5%, and it is projected that the number of DR patients worldwide will significantly increase from 110 million in 2020 to 161 million by 2045[33] (Table 3).

Table 3 Epigenetic regulation-based prevention strategies for diabetic retinopathy.

Prevention level	Target population	Intervention strategies	Epigenetic targets	Expected outcomes	Implementation challenges
Primary prevention (prevent onset)	All diabetic patients	Glycemic control, lifestyle optimization (diet, exercise), early screening	Blocking formation of metabolic memory, preventing epigenetic dysregulation	Significant reduction (30%-40%) in DR incidence	Patient compliance, difficulty in long-term adherence
Secondary prevention (high-risk groups)	Patients with diabetes > 5 years or with epigenetic risk markers	Early curcumol intervention, targeted nutritional supplementation, intensive glycemic control	FTO/MAFG-AS1 axis regulation to inhibit epigenetic abnormalities	Delayed DR onset, alleviation of initial symptoms	Accurate identification of high-risk groups, long-term safety of preventive drugs
Tertiary prevention (early-stage DR)	Patients with mild-to-moderate non-proliferative DR	Curcumol combined with anti-VEGF therapy, microenvironmental regulation	Coordinated intervention in multidimensional epigenetic networks	Halting DR progression, prevention of vision loss	Drug interactions in multi-target combination therapies
Early biomarker detection	Regular screening of diabetic patients	Early diagnostic models based on lncRNA-miRNA-mRNA networks	Epigenetic markers such as FTO/MAFG-AS1, miR-125b-5p/SphK1	Early DR risk detection (2-3 years in advance)	Technical complexity of assays, standardization issues
AI-assisted risk assessment	Newly diagnosed diabetic patients	AI prediction systems integrating clinical data and epigenetic biomarkers	Multi-layered epigenetic modification pattern analysis	Personalized risk evaluation, prediction accuracy > 85%	Data privacy, algorithm interpretability, physician-patient acceptance
Metabolic memory intervention	Patients with significant glycemic fluctuations	Specific epigenetic-modifying drugs to reset metabolic memory	DNA methylation, histone lactylation, m6A modification	Disruption of metabolic memory, prevention of ongoing complications	Defining optimal intervention window, individualized treatment planning

AI: Artificial intelligence; DR: Diabetic retinopathy; lncRNA: Long non-coding RNA; m6A: N6-methyladenosine; mRNA: Messenger RNA; VEGF: Vascular endothelial growth factor.

Epigenetic modification-based early biomarkers offer novel approaches for DR early warning. By combining high-throughput sequencing and bioinformatics analysis, researchers have constructed lncRNA-miRNA-mRNA regulatory networks in DR, identifying several critical regulatory modules, including the FTO/MAFG-AS1 axis and miR-125b-5p/SphK1 axis, thus providing new biomarkers for early diagnosis[1,29,34,35]. Studies have shown that expression changes of these non-coding RNAs occur early in diabetes, preceding clinical symptoms, and therefore possess predictive value.

The metabolic memory theory provides new insight into the persistent progression of DR. Studies by Chen et al[36] and Perrone et al[37] confirmed that epigenetic modifications induced by early hyperglycemic exposure can persist even after blood glucose levels are controlled, leading to ongoing complications. This "metabolic memory" phenomenon is closely associated with epigenetic modifications, notably m6A modification, histone acetylation, and DNA methylation, all playing crucial roles in metabolic memory formation. Yang et al[38] demonstrated a clear link between FTO-mediated m6A modifications and metabolic memory. Wilson-Verdugo et al[39] reported that transient high-glucose exposure induces persistent transcriptional and chromatin changes in endothelial cells, which remain difficult to reverse even after normalizing blood glucose. This explains why DR continues to progress in some patients despite good glycemic control.

Preventive strategies for DR should adopt a multi-level intervention model. Therefore, developing early biomarkers based on the FTO/MAFG-AS1 pathway combined with routine fundus examinations could facilitate early DR detection. In addition, a personalized, artificial intelligence (AI)-assisted risk prediction system for DR can be developed by integrating clinical data with epigenetic biomarkers. This integrative approach enables individualized risk assessment and has the potential to substantially improve predictive accuracy compared to conventional methods.

To establish an effective AI-guided early intervention strategy, we propose a systematic development framework grounded in clinical relevance and methodological rigor. The process begins with problem definition and needs assessment, aimed at identifying key clinical challenges-such as the timely prediction and prevention of DR-and elucidating the limitations of existing diagnostic tools. Subsequently, multimodal data are collected from diverse sources, including electronic health records, retinal imaging, and epigenetic profiling. These datasets undergo preprocessing procedures involving data cleaning, normalization, and feature extraction to enhance data quality and ensure analytical robustness. Machine learning models, such as random forests or deep neural networks, are then employed to construct predictive algorithms. Model training is conducted using labeled datasets, and performance is optimized through hyperparameter tuning and cross-validation to improve both accuracy and generalizability. Model evaluation is carried out on independent test sets to assess predictive robustness and mitigate overfitting. For successful clinical translation, it is essential to develop an interpretable user interface that facilitates communication between the AI system and end-users, including both clinicians and patients. Moreover, seamless integration into existing clinical workflows is critical to ensure practical utility in real-world settings. The inclusion of epigenetic biomarkers further enhances the model’s capacity for individualized risk stratification, thereby advancing the clinical applicability of AI in the early detection and personalized management of DR.

Research confirms that dietary interventions, lifestyle optimization, and early pharmacological interventions can substantially reduce DR risk in high-risk populations[40,41]. Specifically, epigenetic interventions targeting the FTO/MAFG-AS1 pathway could be initiated immediately after diabetes diagnosis, blocking the formation of metabolic memory and preventing DR[1,6,36,37]. Thus, curcumin should be repositioned as a preventive intervention rather than as a treatment for established DR, greatly enhancing its clinical value and application prospects.

Anti-VEGF therapy is currently one of the primary treatment strategies for DR, working by inhibiting VEGF to slow disease progression. Research has demonstrated that anti-VEGF agents such as bevacizumab, ranibizumab, and aflibercept can effectively reduce retinal edema and neovascularization, leading to improved visual outcomes[42]. However, these medications may be associated with side effects, including intraocular inflammation and increased intraocular pressure, and typically require repeated intravitreal injections.

Establishing a large-scale preventive system should involve community screening, risk stratification, and targeted prevention. It is therefore recommended to establish a three-tier DR preventive intervention system: Primary prevention for all diabetic patients emphasizing glycemic control and lifestyle interventions; secondary prevention targeting high-risk patients incorporating epigenetically targeted medications such as curcumin; and tertiary prevention aimed at patients with early-stage DR combining anti-VEGF treatment and epigenetic regulation to prevent disease progression[1,43-45]. This comprehensive system could significantly reduce DR incidence and blindness rates, saving considerable costs for patients and healthcare systems.

HOLISTIC PERSPECTIVE OF MICROENVIRONMENTAL SYNERGISTIC THERAPY

The study primarily focuses on the effects of curcumin on retinal vascular endothelial cells, yet the retina functions as a neurovascular unit involving the coordinated actions of multiple cell types. Traditional therapeutic strategies for retinal diseases have typically concentrated on single-cell types or isolated molecular pathways; however, recent research highlights the retina's intrinsic nature as a neurovascular unit, where neurons, glial cells, vascular components, and supportive structures dynamically interact, forming an intricate functional network essential for tissue homeostasis. This conceptual advancement profoundly impacts the diagnostic and therapeutic paradigms for diseases such as DR and age-related macular degeneration (AMD). In DR, the regulatory mechanisms of FTO vividly illustrate this point. FTO affects retinal microvascular pathology by influencing multiple cell interactions within the retinal microenvironment. Specifically, FTO regulates vascular integrity through transcellular signaling between endothelial cells and pericytes, affecting vascular stability, and coordinates endothelial-microglial cell interactions, inducing microglial activation and neurodegeneration. This leads to an intertwined pathology of vascular abnormalities and neuronal degeneration[6]. The regulatory mechanisms involving FTO highlight a fundamental shift from a single-cell pathological perspective toward a model of cellular network dysregulation. Consequently, future therapeutic strategies should transcend traditional limitations of targeting single pathways and instead adopt systemic regulatory approaches aimed at correcting multi-cellular synergistic imbalances[6].

The spatial organization and metabolic heterogeneity of the retina collectively constitute its complex functional system. As a highly differentiated neurosensory tissue, the retina exhibits significant variability in metabolic activity, gene expression, and cellular interactions. Spatial metabolomics studies revealed remarkable metabolic diversity across different retinal regions, reflecting functional specialization and explaining their differential susceptibility to disease. Sharma et al[19] confirmed that lncRNAs collectively form a complex ceRNA network, influencing the expression of miRNAs and their target genes through competitive miRNA binding. For instance, MIAT, upregulated in DR, regulates VEGF expression by binding miR-150-5p, promoting angiogenesis[23]. Similarly, ANRIL increases VEGF expression by sponging miR-200b, promoting proliferation and tube formation in retinal vascular endothelial cells[24,25]. Recent research suggests that MAFG-AS1 might influence CTNNB1 expression through interaction with miR-424-5p, thereby affecting the Wnt/β-catenin signaling pathway-a key pathway in DR pathogenesis.

Previous studies revealed that lncRNAs regulate gene expression via diverse mechanisms, including epigenetic modifications (e.g., histone methylation and phosphorylation), transcriptional regulation, RNA splicing, and translational control[6,26,27,46]. For example, ANRIL regulates histone modifications on target genes by recruiting the PRC2 complex, while MALAT1 mainly influences gene expression through modulation of SR protein phosphorylation, affecting RNA splicing[28].

Given this complexity, simply targeting individual lncRNAs may be inadequate for optimal therapeutic effects. Thus, researchers propose constructing systematic lncRNA-miRNA-mRNA regulatory networks to deeply investigate how MAFG-AS1 synergizes with other non-coding RNAs[29,30]. This approach integrates RNA-seq, MeRIP-seq, RNA pull-down, and CLIP-seq technologies, comprehensively analyzing lncRNA interactions, providing a theoretical foundation for RNA-network-based DR therapy.

The spatial organization and metabolic heterogeneity of the retina form its complex functional architecture. As a highly differentiated neurosensory tissue, the retina shows significant variability in metabolic activities, gene expression, and cellular interactions[47]. Spatial metabolomics studies have revealed substantial metabolic differences across retinal regions, especially between central and peripheral regions, reflecting functional specialization and regional susceptibility in diseases. Advances in spatial transcriptomics (e.g., MERFISH and Slide-seq V2) further enable the mapping of molecularly distinct cell types within spatial contexts. A recent MERFISH study generated a single-cell spatial atlas of the mouse retina, analyzing over 390000 cells, revealing previously unknown amacrine cell subtypes and spatially dependent gene expression patterns, suggesting location-based functional regulation[18].

The retina’s tight coupling between vascular and neuronal components, especially the interactions between endothelial cells, pericytes, RPE cells, and microglia, constitutes a critical interface for visual function maintenance. Innovative in vitro retinal-chip technologies, mimicking these spatial relationships, confirmed interactions among endothelial cells, pericytes, and RPE cells, underscoring the necessity of preserving cellular networks for visual function[48].

Curcumol, an analog of curcumin, provides new therapeutic insights by regulating the FTO/MAFG-AS1 axis in DR, reducing proliferation, migration, and inflammatory responses in retinal endothelial cells under hyperglycemic conditions, and influencing interactions among pericytes and microglial cells[49]. Curcumol, like curcumin, demonstrates cross-cell antioxidant and anti-inflammatory effects, dose-dependently suppressing endothelial reactive oxygen species production, downregulating inflammatory mediators such as IκBα and COX-2, and protecting multiple cell types, thus overcoming limitations of traditional single-target therapies[50].

Current research emphasizes integrating spatial multi-omics with advanced in vitro models to decode therapeutic effects on the retinal microenvironment[47]. Spatial metabolomics dynamically monitors the impact of compounds like curcumol on cellular metabolism, while sophisticated spatial transcriptomics accurately localizes therapeutic effects. Using biomimetic retinal-chip models, researchers can evaluate drug-induced interactions within multicellular networks, advancing a comprehensive, multidimensional research strategy. This approach elucidates how curcumol modulates vascular permeability, inflammatory cascades, and oxidative stress networks.

Future preventive strategies for DR should adopt multi-tiered interventions. Developing early biomarkers based on the FTO/MAFG-AS1 pathway combined with routine fundus examinations could provide early DR warnings. Additionally, epigenetic interventions targeting this pathway, administered immediately upon diabetes diagnosis, could interrupt metabolic memory formation, thus preventing DR onset[1,6,36,37]. Curcumol and curcumin should therefore be repositioned as preventive agents rather than treatments for established DR, significantly enhancing their clinical potential.

Ultimately, establishing a large-scale preventive system encompassing community-based screening, risk stratification, and targeted prevention is recommended. A three-tiered preventive system should be developed: Primary prevention targeting all diabetic patients through glycemic control and lifestyle interventions; secondary prevention targeting high-risk populations with epigenetic drugs such as curcumin and curcumol; and tertiary prevention for early-stage DR patients combining anti-VEGF treatments and epigenetic regulation to halt disease progression[1,43-45]. This integrated framework could significantly reduce DR incidence and blindness rates, providing substantial economic benefits to patients and healthcare systems.

TRANSLATIONAL APPLICATION PROSPECTS OF NANO-DELIVERY SYSTEMS

Nanotechnology-driven drug delivery systems are reshaping modern therapeutic paradigms through targeted administration, controlled-release mechanisms, and enhanced bioavailability. Traditional drug administration methods face significant limitations due to nonspecific drug distribution, rapid metabolic clearance, and poor bioavailability of hydrophobic compounds. The emergence of nano-carriers provides innovative solutions to overcome biological barriers and achieve precision delivery[51,52]. By designing nanoscale structures, these systems not only protect drug molecules from degradation but also control release kinetics, demonstrating significant advantages in improving therapeutic efficacy and reducing side effects through enhanced stability and transmembrane transport capabilities. PLGA nanoparticles, notable for their biodegradability and Food and Drug Administration-approved safety, have become prominent carriers, validated by encapsulation efficiencies of over 90% for drugs such as curcumin[53]. Liposomes, leveraging their phospholipid bilayer structure, can simultaneously load hydrophilic and hydrophobic drugs, while dendrimers, with their precise branched architecture, achieve accurate control over drug loading and release. These diverse platforms provide adaptable choices for various therapeutic applications[54] (Table 4).

Table 4 Comparison of nano-delivery systems applied in curcumol treatment.

Delivery system	Composition	Mechanism of action	Retinal targeting efficiency	Advantages	Limitations
Conventional oral administration	Raw curcumol or tablets	Absorbed via gastrointestinal tract, systemic distribution	Very low; difficulty penetrating blood-retinal barrier	Convenient administration, high patient compliance	Low bioavailability, hepatic first-pass effect, insufficient retinal concentrations
Intravitreal injection	Curcumol solution	Direct ocular administration, high local concentration	High; direct targeting of retina	Rapid onset, high local drug concentration	Invasive procedure, risk of complications, repeated injections needed
PLGA nanoparticles	PLGA, curcumol	Controlled-release system, extends drug half-life	Moderate; passive targeting	FDA-approved, biodegradable, encapsulation efficiency > 90%	Complex preparation, batch-to-batch variability
Liposomes	Phospholipid bilayer, curcumol	Enhanced cell membrane fusion and uptake	Moderate; surface modifications possible for improved targeting	Can carry both hydrophilic and hydrophobic drugs	Limited stability, strict storage conditions
Macrophage membrane-coated nanoparticles	Macrophage membrane, polymer core, curcumol	Inherits homing capability and immune evasion of source cells	High; specific recognition via membrane surface proteins	Active targeting to inflammatory sites, prolonged retention	Complex preparation technology, challenging scale-up production
Dendrimers	Branched polymers, curcumol	High drug-loading capacity, controlled release	Moderate to high; modifiable with various targeting ligands	Precise branched structure, multifunctionality	Potential toxicity, poor biodegradability

FDA: Food and drug administration; PLGA: Poly (lactic-co-glycolic acid).

In recent years, the integration of biomimetic technologies has advanced nano-delivery systems to higher-order forms, particularly cell membrane-coated nanoparticles, which have introduced new dimensions in targeted therapies[55]. These composite carriers ingeniously combine synthetic nanoparticle cores with natural cellular membrane components, such as macrophage membrane-coated nanoparticles, significantly enhancing active targeting efficiency toward inflammatory lesions and tumor tissues by inheriting the homing capabilities and immune-evasion characteristics of the source cells[56,57]. In ophthalmology, such biomimetic strategies hold unique therapeutic potential, especially for retinal neovascular diseases like AMD, which require delivery systems capable of penetrating complex intraocular barriers to precisely target pathological regions. Cell membrane-coating technology not only extends nanoparticle retention in ocular tissues but also enables precise drug delivery to retinal lesions through membrane-surface protein-mediated specific recognition, offering therapeutic efficacy unattainable by conventional delivery methods[56]. The successful development of these bio-artificial hybrid systems represents a leap from simple drug-loading tools to intelligent, biomimetic therapeutic platforms in nanomedicine, providing refined therapeutic approaches for various complex diseases, including cancers and chronic inflammatory conditions[58].

CONCLUSION

This study establishes curcumol as a multi-functional therapeutic agent for DR, with a mechanism involving epigenetic regulation via the FTO/MAFG-AS1 axis and innovative nano-delivery strategies. Mechanistically, curcumol activates the demethylase activity of FTO, stabilizing MAFG-AS1 and thus inhibiting high glucose-induced vascular leakage, inflammatory responses, and pathological angiogenesis. Single-cell transcriptomics revealed the dual role of FTO: On the one hand, driving endothelial dysfunction through m6A-dependent regulation of CDK2, while on the other hand, exerting antioxidant and anti-inflammatory effects by stabilizing MAFG-AS1. This study delineates a multidimensional epigenetic network integrating m6A methylation, histone lactylation, and DNA methylation, highlighting the potential of curcumol to disrupt metabolic memory and reshape the retinal microenvironment. Moreover, the macrophage membrane-coated biomimetic nanoparticle delivery system enhances the retinal targeting and bioavailability of curcumol, overcoming limitations of conventional therapies.

These findings promote a paradigm shift from passive treatment toward AI-guided preventive strategies, emphasizing early prevention by intervening in metabolic memory and adopting stratified clinical approaches. However, further validation of curcumol's efficacy across diverse diabetes models and its synergy with existing treatments is required. Future studies should integrate spatial multi-omics and advanced retinal-chip models to resolve cell type-specific epigenetic dynamics and optimize precision intervention strategies. By integrating epigenetics, nanotechnology, and systems biology, this study lays a foundation for transformative DR therapy, emphasizing microenvironment homeostasis and preventive medicine.