Association between lncRNAs in plasma exosomes and diabetic retinopathy

miRNAs, piRNAs, and lncRNAs: A triad of non-coding RNAs regulating the neurovascular unit in diabetic retinopathy and their therapeutic potentials

Diabetic Retinopathy (DR), a leading complication of diabetes mellitus, has long been considered as a microvascular disease of the retina. However, recent evidence suggests that DR is a neurovascular disease, characterized by the degeneration of retinal neural tissue and microvascular abnormalities encompassing ischemia, neovascularization, and blood-retinal barrier breakdown, ultimately leading to blindness. The intricate relationship between the retina and vascular cells constitutes a neurovascular unit, a multi-cellular framework of retinal neurons, glial cells, immune cells, and vascular cells, which facilitates neurovascular coupling, linking neuronal activity to blood flow. These interconnections between the neurovascular components get compromised due to hyperglycemia and are further associated with the progression of DR early on in the disease. As a result, therapeutic approaches are needed to avert the advancement of DR by acting at its initial stage to delay or prevent the pathogenesis. Non-coding RNAs (ncRNAs) such as microRNAs, piwi-interacting RNAs, and long non-coding RNAs regulate various cellular components in the neurovascular unit. These ncRNAs are key regulators of neurodegeneration, apoptosis, inflammation, and oxidative stress in DR. In this review, research related to alterations in the expression of ncRNAs and, correspondingly, their effect on the disintegration of the neurovascular coupling will be discussed briefly to understand the potential of ncRNAs as therapeutic targets for treating this debilitating disease.

Deciphering the role of exosomal derived regulatory noncoding RNAs as potential biomarkers for diabetic retinopathy: a systematic review

About one-third of individuals with diabetes develop diabetic retinopathy (DR), with one-tenth experiencing vision-threatening conditions such as diabetic macular edema (DME) or proliferative diabetic retinopathy (PDR). Current treatments only show recovery in 50% of cases, and the disease often remains asymptomatic. Therefore, novel early detection methods and new biomarkers are crucial. Our study aims to summarise evidence on the role of altered exosomal regulatory noncoding RNAs in DR, based on human studies. Observational studies delineating the different exosomal noncoding RNAs in DR were searched systematically from inception to June 2024 in PubMed-MEDLINE and SCOPUS databases. Preferred Reporting Items of Systematic Reviews and Meta-analysis (PRISMA) 2020 guidelines was used to conduct this systematic review (Prospero ID: CRD42023406724). We synthesised data from 13 human studies that assessed the expression of exosomal regulatory ncRNAs from individuals with DR. Among the 13 studies, nine focused on miRNA, while three examined lncRNA and one on circRNA. Although no common genes were identified across the studies, the review underscores the critical roles of exosomal noncoding RNAs in the pathogenesis of diabetic retinopathy, highlighting their potential as therapeutic targets. Future studies should aim for a unified approach in terms of sample selection, RNA analysis, and appropriate controls for a comprehension of exosomal expression patterns for early diagnosis of DR.

Approaches and Challenges in Characterizing the Molecular Content of Extracellular Vesicles for Biomarker Discovery

Extracellular vesicles (EVs) are lipid bilayer nanoparticles released from all known cells and are involved in cell-to-cell communication via their molecular content. EVs have been found in all tissues and body fluids, carrying a variety of biomolecules, including DNA, RNA, proteins, metabolites, and lipids, offering insights into cellular and pathophysiological conditions. Despite the emergence of EVs and their molecular contents as important biological indicators, it remains difficult to explore EV-mediated biological processes due to their small size and heterogeneity and the technical challenges in characterizing their molecular content. EV-associated small RNAs, especially microRNAs, have been extensively studied. However, other less characterized RNAs, including protein-coding mRNAs, long noncoding RNAs, circular RNAs, and tRNAs, have also been found in EVs. Furthermore, the EV-associated proteins can be used to distinguish different types of EVs. The spectrum of EV-associated RNAs, as well as proteins, may be associated with different pathophysiological conditions. Therefore, the ability to comprehensively characterize EVs' molecular content is critical for understanding their biological function and potential applications in disease diagnosis. Here, we set out to provide an overview of EV-associated RNAs and proteins as well as approaches currently being used to characterize them.

Biofluid-Derived Exosomal LncRNAs: Their Potential in Obesity and Related Comorbidities

Obesity has escalated into a critical global health crisis, tripling in prevalence since the mid-1970s. This increase mirrors the rise in metabolic-associated diseases such as type 2 diabetes (T2D) and its complications, certain cancers, and cardiovascular conditions. While substantial research efforts have enriched our understanding and led to the development of innovative management strategies for these diseases, the suboptimal response rates of existing therapies remain a major obstacle to effectively managing obesity and its associated conditions. Over the years, inter-organ communication (IOC) has emerged as a crucial factor in the development and progression of metabolic disorders. Exosomes, which are nano-sized vesicular couriers released by cells, play a significant role in this communication by transporting proteins, lipids, and nucleic acids across cellular landscapes. The available evidence indicates that exosomal RNAs present in biofluids such as blood, urine, milk, vitreous humor (VH), and cerebrospinal fluid (CSF) are altered in numerous diseases, suggesting their diagnostic and therapeutic potential. Long non-coding RNAs contained in exosomes (exo-lncRNAs) have attracted considerable interest, owing to their ability to interact with critical components involved in a multitude of metabolic pathways. Recent studies have found that alterations in exo-lncRNAs in biofluids correlate with several metabolic parameters in patients with metabolic-associated conditions; however, their exact roles remain largely unclear. This review highlights the diagnostic and therapeutic potential of exosomal lncRNAs in obesity and its associated conditions, emphasizing their role in IOC and disease progression, aiming to pave the way for further research in this promising domain.

Potential Diagnostic Markers of Diabetic Retinopathy: Serum LncRNA MIAT, HOTTIP, SNHG16

Purpose

To study the expression and diagnostic ability of the long noncoding RNAs (lncRNAs) MIAT, HOTTIP, and SNHG16 in serum of patients with diabetic retinopathy.

Methods

A total of 70 healthy controls and 195 patients with Type 2 Diabetes (T2D) were collected. T2D patients include 65 patients with Nondiabetic retinopathy (NDR), 65 patients with Nonproliferative diabetic retinopathy (NPDR) and 65 patients with Proliferative diabetic retinopathy (PDR). The relative expression of MIAT, HOTTIP and SNHG16 in participant serum was measured through Real-time fluorescence quantitative polymerase chain reaction to compare the differential expression between the groups. t test, Mann‒Whitney U-test, Pearson's chi-square test and the receiver operating characteristic (ROC) curve were used to analyze the expression of these LncRNAs and their diagnostic ability for DR.

Results

We compare the healthy control group with T2D group, healthy control group with NDR group, NDR group with DR (NPDR+PDR) group, and NPDR group with PDR group. When NDR group was compared with the healthy control group, there was no difference between MIAT (p>0.05)and HOTTIP (p>0.05), only the relative expression of SNHG16(p<0.05) was different and it's ROC curve had identification significance. In the remaining inter-group comparisons, the differences in the expression of MIAT (p<0.05), HOTTIP (p<0.05) and SNHG16 (p<0.05) were statistically significant, and their ROC curves were all had identification significance.

Conclusion

These findings prove that serum LncRNA MIAT, HOTTIP and SNHG16 may be used as potential markers to monitor the progress of DR.

Advances in Extracellular-Vesicles-Based Diagnostic and Therapeutic Approaches for Ocular Diseases

Extracellular vesicles (EVs) are nanoscale membrane vesicles of various sizes that can be secreted by most cells. EVs contain a diverse array of cargo, including RNAs, lipids, proteins, and other molecules with functions of intercellular communication, immune modulation, and regulation of physiological and pathological processes. The biofluids in the eye, including tears, aqueous humor, and vitreous humor, are important sources for EV-based diagnosis of ocular disease. Because the molecular cargos may reflect the biology of their parental cells, EVs in these biofluids, as well as in the blood, have been recognized as promising candidates as biomarkers for early diagnosis of ocular disease. Moreover, EVs have also been used as therapeutics and targeted drug delivery nanocarriers in many ocular disorders because of their low immunogenicity and superior biocompatibility in nature. In this review, we provide an overview of the recent advances in the field of EV-based studies on the diagnosis and therapeutics of ocular disease. We summarized the origins of EVs applied in ocular disease, assessed different methods for EV isolation from ocular biofluid samples, highlighted bioengineering strategies of EVs as drug delivery systems, introduced the latest applications in the diagnosis and treatment of ocular disease, and presented their potential in the current clinical trials. Finally, we briefly discussed the challenges of EV-based studies in ocular disease and some issues of concern for better focusing on clinical translational studies of EVs in the future.

Exosomes as Emerging Regulators of Immune Responses in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by high blood glucose levels resulting from insulin resistance and impaired insulin secretion. Immune dysregulation-mediated chronic low-grade inflammation is a critical factor that poses a significant risk to the metabolic disorders of T2DM and its related complications. Exosomes, as small extracellular vesicles secreted by various cells, have emerged as essential regulators of intercellular communication and immune regulation. In this review, we summarize the current understanding of the role of exosomes derived from immune and nonimmune cells in modulating immune responses in T2DM by regulating immune cell functions and cytokine production. More importantly, we suggest potential strategies for the clinical applications of exosomes in T2DM management, including biomarkers for disease diagnosis and monitoring, exosome-based therapies for drug delivery vehicles, and targeted therapy for exosomes.

Emerging role of extracellular vesicles in diabetic retinopathy

Diabetic retinopathy (DR), a complex complication of diabetes mellitus (DM), is a leading cause of adult blindness. Hyperglycemia triggers DR, resulting in microvascular damage, glial apoptosis, and neuronal degeneration. Inflammation and oxidative stress play crucial roles during this process. Current clinical treatments for DR primarily target the advanced retinal disorder but offer limited benefits with inevitable side effects. Extracellular vesicles (EVs) exhibit unique morphological features, contents, and biological properties and can be found in cell culture supernatants, various body fluids, and tissues. In DR, EVs with specific cargo composition would induce the reaction of receptor cell once internalized, mediating cellular communication and disease progression. Increasing evidence indicates that monitoring changes in EV quantity and content in DR can aid in disease diagnosis and prognosis. Furthermore, extensive research is investigating the potential of these nanoparticles as effective therapeutic agents in preclinical models of DR. This review explores the current understanding of the pathological effects of EVs in DR development, discusses their potential as biomarkers and therapeutic strategies, and paves the way for further research and therapeutic advancements.

Extracellular vesicles in degenerative retinal diseases: A new therapeutic paradigm

Nanoscale extracellular vesicles (EVs), consisting of exomers, exosomes and microvesicles/ectosomes, have been extensively investigated in the last 20 years, although their biological role is still something of a mystery. EVs are involved in the transfer of lipids, nucleic acids and proteins from donor to recipient cells or distant organs as well as regulating cell-cell communication and signaling. Thus, EVs are important in intercellular communication and this is not limited to sister cells, but may also mediate the crosstalk between different cell types even over long distances. EVs play crucial functions in both cellular homeostasis and the pathogenesis of diseases, and since their contents reflect the status of the donor cell, they represent an additional valuable source of information for characterizing complex biological processes. Recent advances in isolation and analytical methods have led to substantial improvements in both characterizing and engineering EVs, leading to their use either as novel biomarkers for disease diagnosis/prognosis or even as novel therapies. Due to their capacity to carry biomolecules, various EV-based therapeutic applications have been devised for several pathological conditions, including eye diseases. In the eye, EVs have been detected in the retina, aqueous humor, vitreous body and also in tears. Experiences with other forms of intraocular drug applications have opened new ways to use EVs in the treatment of retinal diseases. We here provide a comprehensive summary of the main in vitro, in vivo, and ex vivo literature-based studies on EVs' role in ocular physiological and pathological conditions. We have focused on age-related macular degeneration, diabetic retinopathy, glaucoma, which are common eye diseases leading to permanent blindness, if not treated properly. In addition, the putative use of EVs in retinitis pigmentosa and other retinopathies is discussed. Finally, we have reviewed the potential of EVs as therapeutic tools and/or biomarkers in the above-mentioned retinal disorders. Evidence emerging from experimental disease models and human material strongly suggests future diagnostic and/or therapeutic exploitation of these biological agents in various ocular disorders with a good possibility to improve the patient's quality of life.

Exosomes as biomarkers and therapy in type 2 diabetes mellitus and associated complications

Type 2 diabetes mellitus (T2DM) is one of the most prevalent metabolic disorders worldwide. However, T2DM still remains underdiagnosed and undertreated resulting in poor quality of life and increased morbidity and mortality. Given this ongoing burden, researchers have attempted to locate new therapeutic targets as well as methodologies to identify the disease and its associated complications at an earlier stage. Several studies over the last few decades have identified exosomes, small extracellular vesicles that are released by cells, as pivotal contributors to the pathogenesis of T2DM and its complications. These discoveries suggest the possibility of novel detection and treatment methods. This review provides a comprehensive presentation of exosomes that hold potential as novel biomarkers and therapeutic targets. Additional focus is given to characterizing the role of exosomes in T2DM complications, including diabetic angiopathy, diabetic cardiomyopathy, diabetic nephropathy, diabetic peripheral neuropathy, diabetic retinopathy, and diabetic wound healing. This study reveals that the utilization of exosomes as diagnostic markers and therapies is a realistic possibility for both T2DM and its complications. However, the majority of the current research is limited to animal models, warranting further investigation of exosomes in clinical trials. This review represents the most extensive and up-to-date exploration of exosomes in relation to T2DM and its complications.

Advances in Therapeutic Applications of Extracellular Vesicles

Extracellular vesicles (EVs) are nanoscale bilayer phospholipid membrane vesicles released by cells. Contained large molecules such as nucleic acid, protein, and lipid, EVs are an integral part of cell communication. The contents of EVs vary based on the cell source and play an important role in both pathological and physiological conditions. EVs can be used as drugs or targets in disease treatment, and changes in the contents of EVs can indicate the progression of diseases. In recent years, with the continuous exploration of the structure, characteristics, and functions of EVs, the potential of engineered EVs for drug delivery and therapy being constantly explored. This review provides a brief overview of the structure, characteristics and functions of EVs, summarizes the advanced application of EVs and outlook on the prospect of it. It is our hope that this review will increase understanding of the current development of medical applications of EVs and help us overcome future challenges.