PHD2 attenuates high-glucose-induced blood retinal barrier breakdown in human retinal microvascular endothelial cells by regulating the Hif-1α/VEGF pathway

Hyperglycemia-induced blood-brain barrier dysfunction: Mechanisms and therapeutic interventions

The blood-brain barrier (BBB) serves as a highly selective interface that regulates the transport of molecules between the blood and the brain. Its integrity is essential for maintaining neuronal homeostasis and preventing neuroinflammation. Hyperglycemia, a hallmark of diabetes, is linked to cognitive deficits and central nervous system (CNS) pathologies, including vascular dementia, stroke, and Alzheimer's disease, with BBB damage as a potential contributing factor. As the global prevalence of diabetes rises, understanding the connection between hyperglycemia and BBB dysfunction may facilitate the development of novel treatments that protect or restore BBB integrity, thereby alleviating the neurological complications of diabetes. Furthermore, it may aid in the development of targeted therapies for diabetes-related neurological complications. This literature review examines the emerging insights into the relationship between hyperglycemia and BBB dysfunction. It focuses on the mechanisms underlying BBB dysfunction, the clinical manifestations of this dysfunction in diabetes and cerebrovascular diseases, and potential therapeutic interventions.

Peptides based on the interface of hnRNPA2B1-transthyretin complex repress retinal angiogenesis in diabetic retinopathy

BACKGROUND

Heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) plays a vital role in angiogenesis, when its nucleic acid-binding domain is occupied by transthyretin (TTR), the neovascularization of human retinal microvascular endothelial cells (hRECs) is repressed under hyperglycemic conditions.

METHODS

HnRNPA2B1-targeting peptides (THIPs) were designed based on the core fragments at the TTR-hnRNPA2B1 interface. Biacore, Langmuir equilibrium adsorption, and co-immunoprecipitation (co-IP) assays were performed to determine the association between the THIPs and hnRNPA2B1. Proliferation and DNA synthesis in hRECs were detected using CCK-8 and EdU assays. Transwell, wound healing, and tube formation assays were used to evaluate migratory and the angiogenic capacity of hRECs. Related RNA and protein expression levels were tested by quantitative PCR and western blot assays, respectively. Streptozotocin (STZ)-induced diabetic retinopathy (DR) model rats were intravitreally injected with 5 μL of AAV9 virus (1 × 1012 vg/mL) every 8 weeks, with sterile saline used as control. After 16 weeks, the retinas were extracted and subjected to Evans blue leakage and retinal trypsin digestion assays. Retinal paraffin sections were prepared and stained with hematoxylin and eosin (H&E) or subjected to immunohistochemical or immunofluorescence assays.

RESULTS

Biacore, Langmuir equilibrium adsorption, and co-IP analyses demonstrated that the four designed THIPs specifically recognized hnRNPA2B1. CCK-8 and EdU labeling assays showed that the THIPs inhibited proliferation and DNA synthesis in hRECs under hyperglycemia. Transwell, wound healing and tube formation assays demonstrated that the THIPs inhibited the migratory and angiogenic capacity of hRECs. Quantitative PCR and western blot assays suggested that the THIPs exerted their effects via the STAT4/miR-223-3p/FBXW7 and the downstream Notch1/Akt/mTOR axes. In vivo studies using DR model rat revealed that the intravitreal administration of THIP-4 significantly mitigated retinal leakage, capillary decellularization, pericyte loss, fibrosis, and gliosis during DR progression.

CONCLUSION

Our findings demonstrated that under hyperglycemia, THIP-4 suppressed DR progression via the STAT4/miR-223-3p/FBXW7 and Notch1/Akt/mTOR axes both in vitro and in vivo. These results indicated that THIP-4 has strong potential for clinical application in DR and other angiogenesis associated diseases.

The Role of Non-coding RNAs in Diabetic Retinopathy: Mechanistic Insights and Therapeutic Potential

Diabetic retinopathy (DR) is the most common ocular complication in diabetic patients, accounting for a significant proportion of diabetes-related eye diseases. Approximately one-third of diabetic patients worldwide are affected by DR. Microvascular diseases, which can lead to severe visual impairment or even blindness, pose a significant threat to the quality of life and visual function of patients. However, the underlying cellular mechanisms of DR remain unclear. Recent studies have discovered that, apart from traditional pathological mechanisms, epigenetic mechanisms may alter key biological processes through gene expression dysregulation, thereby promoting the onset and progression of DR. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), play crucial roles in gene regulation and disease pathways. Taking this into account, exploring innovative therapies and developing effective management strategies is crucial. This review focuses on the latest research on ncRNAs in DR, emphasizing their regulatory functions in cell proliferation, apoptosis, and inflammatory responses, and discusses the potential mechanisms by which ncRNAs accelerate disease progression. Additionally, the article highlights the potential role of exosome-associated ncRNAs in DR, proposing their use as early diagnostic markers and targeted therapeutic tools. By integrating current research, this review aims to provide guidance for future studies and promote the advancement of precision diagnostics and therapeutic efficacy in DR.

Sodium butyrate inhibits activation of ROS/NF-κB/NLRP3 signaling pathway and angiogenesis in human retinal microvascular endothelial cells

BACKGROUND

To determine the impact of sodium butyrate on the activation of the reactive oxygen species (ROS)/nuclear factor kappa B (NF-κB)/NLR family pyrin domain containing 3 (NLRP3) signaling pathway and angiogenesis in human retinal microvascular endothelial cells (HRMECs) caused by high glucose (HG).

METHODS

HRMECs were grown for 24 h or 72 h in HG solution (30 mmol/L D-glucose) with 5 mM NaB. Using Cell Counting Kit-8, the effects of HG and NaB levels on the viability of HRMECs were examined. Using various kits, intracellular ROS levels, lactate dehydrogenase (LDH), and Malondialdehyde (MDA) in cell supernatants were measured. Western blot, Immunofluorescence, and Real-time quantitative polymerase chain reaction were employed to quantify protein and messenger RNA expression. Using wound-healing and tube formation tests, the migratory proficiency and angiogenesis of HRMECs were evaluated.

RESULTS

NaB demonstrated a reduction in ROS production, as well as the release of LDH and MDA in HG-induced HRMECs. Additionally, NaB led to a decrease in protein expression of phosphorylation of NF-κB, NLRP3, Caspase 1, interleukin, vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. The impact of HG on zonula occluden-1, a tight junction protein, was attenuated by NaB. Furthermore, NaB inhibited the migration and tube formation of HRMECs partly by ROS/NF-κB/NLRP3 pathway.

CONCLUSION

NaB suppresses the activation of ROS/NF-κB/NLRP3 signaling pathway and angiogenesis in HRMECs induced by HG.

The Impact of the Blood-Brain Barrier and Its Dysfunction in Parkinson's Disease: Contributions to Pathogenesis and Progression

Parkinson's disease (PD) is a brain disorder in which neuronal cells responsible for the release of dopamine, a neurotransmitter that controls movement, are degenerated or impaired in the substantia nigra and basal ganglia. The disease typically affects people over the age of 5 and presents with a variety of motor and nonmotor dysfunctions, which are unique to each person. The impairment of the blood-brain barrier (BBB) and blood retinal barrier (BRB) due to age-related causes such as weakness of tight junctions or rare genetic factors allows several metabolic intermediates to reach and accumulate inside neurons such as Lewy bodies and α-synuclein, disrupting neuronal homeostasis and leading to genetic and epigenetic changes, e.g., damage to the DNA repair system. This perspective highlights the importance of blood barriers, such as the BBB and BRB, in the progression of PD, as the aggregation of Lewy bodies and α-synuclein disrupts neuronal homeostasis. Genetic and epigenetic factors, neuroinflammation, oxidative stress, and mitochondrial dysfunction play crucial roles in the progression of the disease. The implications of these findings are significant; identifying synaptic dysfunction could lead to earlier diagnosis and treatment, while developing targeted therapies focused on preserving synaptic function may slow or halt disease progression. Understanding the various genetic forms of PD could enable more personalized medicine approaches, and using patient-derived midbrain neurons for research may improve the accuracy of PD models due to the implications of an impaired BBB.

Pharmacology of Hydrogen Sulfide and Its Donors in Cardiometabolic Diseases

Cardiometabolic diseases (CMDs) are major contributors to global mortality, emphasizing the critical need for novel therapeutic interventions. Hydrogen sulfide (H2S) has garnered enormous attention as a significant gasotransmitter with various physiological, pathophysiological, and pharmacological impacts within mammalian cardiometabolic systems. In addition to its roles in attenuating oxidative stress and inflammatory response, burgeoning research emphasizes the significance of H2S in regulating proteins via persulfidation, a well known modification intricately associated with the pathogenesis of CMDs. This review seeks to investigate recent updates on the physiological actions of endogenous H2S and the pharmacological roles of various H2S donors in addressing diverse aspects of CMDs across cellular, animal, and clinical studies. Of note, advanced methodologies, including multiomics, intestinal microflora analysis, organoid, and single-cell sequencing techniques, are gaining traction due to their ability to offer comprehensive insights into biomedical research. These emerging approaches hold promise in characterizing the pharmacological roles of H2S in health and diseases. We will critically assess the current literature to clarify the roles of H2S in diseases while also delineating the opportunities and challenges they present in H2S-based pharmacotherapy for CMDs. SIGNIFICANCE STATEMENT: This comprehensive review covers recent developments in H2S biology and pharmacology in cardiometabolic diseases CMDs. Endogenous H2S and its donors show great promise for the management of CMDs by regulating numerous proteins and signaling pathways. The emergence of new technologies will considerably advance the pharmacological research and clinical translation of H2S.

Qi-Ju-Di-Huang-Pill delays the progression of diabetic retinopathy

ETHNOPHARMACOLOGICAL RELEVANCE

Qi-Ju-Di-Huang-Pill (QJDH pill) is a Chinese decoction. Although it is commonly used to treat eye conditions, such as diabetic retinopathy (DR), its exact mechanism of action is unknown.

AIM OF THE STUDY

To investigate the specific mechanism by which QJDH pill slows the progression of diabetic retinopathy (DR) based on animal and cellular experiments.

MATERIAL AND METHODS

The major components of QJDH pill were characterized by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLCMS/MS). C57BL/6J mice were randomly divided into five groups as follows: normal group (control group), model group (STZ group), low-dosage QJDH pill group (QJDH-L group), medium-dosage QJDH pill group (QJDH-M group) and high-dosage QJDH pill group (QJDH-H group). Changes in water intake, urination, food intake, and body mass were monitored weekly, while changes in blood glucose were monitored monthly. Fluorescein fundus angiography (FFA), optical coherence tomography angiography (OCTA), and optical coherence tomography (OCT) were utilized to analyze the changes in fundus imaging indications. Hematoxylin & eosin (H&E) and transmission electron microscopy (TEM) were employed to examine histopathologic and ultrastructural changes in retina. The levels of interleukin-6 (IL-6), interleukin-17 (IL-17), tumor necrosis factor-α (TNF-α), and vascular endothelial growth factor (VEGF) in peripheral blood were detected using Enzyme-linked immunosorbent assay (ELISA). The mouse retina apoptotic cells were labeled with green fluorescence via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (Tunel). The protein levels of Bcl-2-Associated X (Bax), B cell lymphoma 2 (Bcl-2), Caspase-3, PI3K, phosphorylated PI3K (p-PI3K), protein kinase B (AKT) and phosphorylated AKT (p-AKT) were quantified by Western blot (WB). The retinal pigment epithelium (RPE) cells were cultured and classified into five groups as follows: normal glucose group (NG group), high glucose group (HG group), high glucose + QJDH pill group (HG + QJDH group), high glucose + inhibitor group (HG + LY294002 group), and high glucose + inhibitor + QJDH pill group (HG + LY294002 + QJDH group). Cell viability and apoptosis were detected via Cell Counting Kit-8 (CCK8) and then analyzed by flow cytometry.

RESULTS

In vivo experiments revealed that the QJDH pill effectively reduced blood glucose, symptoms of increased water intake, elevated urination, increased food intake and decreased body mass in DR mice. QJDH pill also slowed the development of a series of fundus imaging signs, such as retinal microangiomas, tortuous dilatation of blood vessels, decreased vascular density, and thinning of retinal thickness, downregulated IL-6, IL-17, TNF-α, and VEGF levels in peripheral blood, and inhibited retinal cell apoptosis by activating the PI3K/AKT signaling pathway. Moreover, in vitro experiments showed that high glucose environment inhibited RPE cell viability and activated RPE cell apoptosis pathway. In contrast, lyophilized powder of QJDH pill increased RPE cell viability, protected RPE cells from high glucose-induced damage, and decreased apoptosis of RPE cells by activating the pi3k pathway.

CONCLUSION

QJDH pill induces hypoglycemic, anti-inflammatory effects, anti-VEGF and anti-retinal cell apoptosis by activating PI3K/AKT signaling pathway, and thus can protect the retina and slow the DR progression.

Pathogenesis of diabetic complications: Exploring hypoxic niche formation and HIF-1α activation

Hypoxia is a common feature of diabetic tissues, which highly correlates to the progression of diabetes. The formation of hypoxic context is induced by disrupted oxygen homeostasis that is predominantly driven by vascular remodeling in diabetes. While different types of vascular impairments have been reported, the specific features and underlying mechanisms are yet to be fully understood. Under hypoxic condition, cells upregulate hypoxia-inducible factor-1α (HIF-1α), an oxygen sensor that coordinates oxygen concentration and cell metabolism under hypoxic conditions. However, diabetic context exploits this machinery for pathogenic functions. Although HIF-1α protects cells from diabetic insult in multiple tissues, it also jeopardizes cell function in the retina. To gain a deeper understanding of hypoxia in diabetic complications, we focus on the formation of tissue hypoxia and the outcomes of HIF-1α dysregulation under diabetic context. Hopefully, this review can provide a better understanding on hypoxia biology in diabetes.

Suppression of cAMP/PKA/CREB signaling ameliorates retinal injury in diabetic retinopathy

The blood-retinal barrier (BRB), homeostasis, neuronal integrity, and metabolic processes are all directly influenced by Müller cells, the most important retinal glial cells. We isolated primary Müller cells from Sprague-Dawley (SD) neonatal rats and treated them with glucose at varying doses. CCK-8 was used to quantify cellular viability, and a TUNEL assay was performed to detect cell apoptosis. ELISA, immunofluorescence, and western blotting were used to assess cAMP/PKA/CREB signaling, Kir4.1, AQP4, GFAP, and VEGF levels, respectively. H&E staining was used to examine histopathological alterations in diabetic retinopathy (DR)-affected retinal tissue in rats. As glucose concentration increases, gliosis of Müller cells became apparent, as evidenced by a decline in cell activity, an increase in apoptosis, downregulation of Kir4.1 level, and overexpression of GFAP, AQP4, and VEGF. Treatments with low, intermediate, and high glucose levels led to aberrant activation of cAMP/PKA/CREB signaling. Interestingly, blocking cAMP and PKA reduced high glucose-induced Müller cell damage and gliosis by a significant amount. Further in vivo results suggested that cAMP or PKA inhibition significantly improved edema, bleeding, and retinal disorders. Our findings showed that high glucose exacerbated Müller cell damage and gliosis via a mechanism involving cAMP/PKA/CREB signaling.

Effects of Lycium barbarum L. Polysaccharides on Vascular Retinopathy: An Insight Review

Vascular retinopathy is a pathological change in the retina caused by ocular or systemic vascular diseases that can lead to blurred vision and the risk of blindness. Lycium barbarum polysaccharides (LBPs) are extracted from the fruit of traditional Chinese medicine, L. barbarum. They have strong biological activities, including immune regulation, antioxidation, and neuroprotection, and have been shown to improve vision in numerous studies. At present, there is no systematic literature review of LBPs on vascular retinal prevention and treatment. We review the structural characterization and extraction methods of LBPs, focus on the mechanism and pharmacokinetics of LBPs in improving vascular retinopathy, and discuss the future clinical application and lack of work. LBPs are involved in the regulation of VEGF, Rho/ROCK, PI3K/Akt/mTOR, Nrf2/HO-1, AGEs/RAGE signaling pathways, which can alleviate the occurrence and development of vascular retinal diseases in an inflammatory response, oxidative stress, apoptosis, autophagy, and neuroprotection. LBPs are mainly absorbed by the small intestine and stomach and excreted through urine and feces. Their low bioavailability in vivo has led to the development of novel dosage forms, including multicompartment delivery systems and scaffolds. Data from the literature confirm the medicinal potential of LBPs as a new direction for the prevention and complementary treatment of vascular retinopathy.