Gambogic acid ameliorates diabetes-induced proliferative retinopathy through inhibition of the HIF-1α/VEGF expression via targeting PI3K/AKT pathway

Biomimetic Nanomodulators With Synergism of Photothermal Therapy and Vessel Normalization for Boosting Potent Anticancer Immunity

Combination therapy using photothermal therapy (PTT) and immunotherapy is one of the most promising approaches for eliciting host immune responses to ablate tumors. However, its therapeutic efficacy is limited due to inefficient immune cell infiltration and cellular immune responses. In this study, a biomimetic immunostimulatory nanomodulator, Tm@PDA-GA (4T1 membrane@polydopamine-gambogic acid), with homologous targeting is developed. The 4T1 membrane (Tm) coating reduced immunogenicity and facilitated uptake of Tm@PDA-GA by tumor cells. Polydopamine (PDA) as a drug carrier can induce PTT under near-infrared ray (NIR) irradiation and immunogenic cell death (ICD) to activate dendritic cells (DCs). Moreover, Tm@PDA-GA on-demand released gambogic acid (GA) in an acidic tumor microenvironment, inhibiting the expression of heat shock proteins (HSPs) for synergetic chemo-photothermal anti-tumor activity and increasing the ICD of 4T1 cells. More importantly, GA can normalize the vessels via HIF-1α and VEGF inhibition to enhance immune infiltration and alleviate hypoxia stress. Thus, Tm@PDA-GA induced ICD, activated DCs, stimulated cytotoxic T cells, and suppressed Tregs. Moreover, Tm@PDA-GA is combined with anti-PD-L1 to further augment the tumor immune response and effectively suppress tumor growth and lung metastasis. In conclusion, biomaterial-mediated PTT combined with vessel normalization is a promising strategy for effective immunotherapy of triple-negative breast cancer (TNBC).

Pinpointing Novel Plasma and Brain Proteins for Common Ocular Diseases: A Comprehensive Cross-Omics Integration Analysis

The pathogenesis of ocular diseases (ODs) remains unclear, although genome-wide association studies (GWAS) have identified numerous associated genetic risk loci. We integrated protein quantitative trait loci (pQTL) datasets and five large-scale GWAS summary statistics of ODs under a cutting-edge systematic analytic framework. Proteome-wide association studies (PWAS) identified plasma and brain proteins associated with ODs, and 11 plasma proteins were identified by Mendelian randomization (MR) and colocalization (COLOC) analyses as being potentially causally associated with ODs. Five of these proteins (protein-coding genes ECI1, LCT, and NPTXR for glaucoma, WARS1 for age-related macular degeneration (AMD), and SIGLEC14 for diabetic retinopathy (DR)) are newly reported. Twenty brain-protein-OD pairs were identified by COLOC analysis. Eight pairs (protein-coding genes TOM1L2, MXRA7, RHPN2, and HINT1 for senile cataract, WARS1 and TDRD7 for AMD, STAT6 for myopia, and TPPP3 for DR) are newly reported in this study. Phenotype-disease mapping analysis revealed 10 genes related to the eye/vision phenotype or ODs. Combined with a drug exploration analysis, we found that the drugs related to C3 and TXN have been used for the treatment of ODs, and another eight genes (GSTM3 for senile cataract, IGFBP7 and CFHR1 for AMD, PTPMT1 for glaucoma, EFEMP1 and ACP1 for myopia, SIRPG and CTSH for DR) are promising targets for pharmacological interventions. Our study highlights the role played by proteins in ODs, in which brain proteins were taken into account due to the deepening of eye-brain connection studies. The potential pathogenic proteins finally identified provide a more reliable reference range for subsequent medical studies.

The Role of Natural Products in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most severe complications of diabetes mellitus and potentially leads to significant visual impairment and blindness. The complex mechanisms involved in the pathological changes in DR make it challenging to achieve satisfactory outcomes with existing treatments. Diets conducive to glycemic control have been shown to improve outcomes in diabetic patients, thus positioning dietary interventions as promising avenues for DR treatment. Investigations have demonstrated that natural products (NPs) may effectively manage DR. Many types of natural compounds, including saponins, phenols, terpenoids, flavonoids, saccharides, alkaloids, and vitamins, have been shown to exert anti-inflammatory, antioxidant, anti-neovascular, and antiapoptotic effects in vivo and in vitro. Nevertheless, the clinical application of NPs still faces challenges, such as suboptimal specificity, poor bioavailability, and a risk of toxicity. Prospective clinical studies are imperative to validate the therapeutic potential of NPs in delaying or preventing DR.

Exploring the mechanism of Bushen Huoxue prescription in the treatment of early diabetic retinal edema from the perspective of inner blood-retinal barrier injury

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic retinopathy (DR) is one of the most severe complications of diabetes mellitus, diabetes belongs to the category of "emaciation-thirst disease" in traditional Chinese medicine (TCM). Bushen Huoxue Prescription (BHP) is composed of traditional Chinese materia medica, which has therapeutic effects on DR and early diabetic retinal edema (EDRE). However, the therapeutic mechanism is unclear.

AIM OF THE STUDY

Exploring the mechanism of BHP against EDRE.

METHODS

Feeding Sprague Dawley (SD) rats a high-fat, high-sugar diet as well as providing intraperitoneal injections of streptozotocin (STZ) to promote inner blood-retinal barrier (iBRB) damage that can trigger EDRE, evaluating the therapeutic effect of BHP by the level of expressiveness of TJ proteins (ZO-1,Occludin) of the iBRB and the leakage of rhodamine B isothiocyanate (RITC) in the retina. The combination of network pharmacology and metabolomics was employed to study the mechanism of BHP in preventing of EDRE, then four proteins which were closely to the damage of iBRB were chosen for the validation by employing Western Blot (WB).

RESULTS

Research of network pharmacology had shown that BHP had efficacy against EDRE by regulating targets such as AKT1, ALB, TNF, PPARG, etc, its potential pathways mainly involving signaling pathways such as HIF-1. In untargeted metabolomics analysis of serum, 15 differential metabolites were identified, with the metabolic pathways focusing on ketone body metabolism and synthesis, sphingolipid metabolism and phenylalanine metabolism. The conclusions of metabolomics and network pharmacology revealed that BHP can treat EDRE by alleviating hypoxia and oxidative stress and exerting protection of the iBRB. Finally, BHP's protection behavior of the iBRB was validated by WB experiments.

CONCLUSION

Through integrating pharmacodynamics, network pharmacology and metabolomics, BHP was discovered to have a crucial function in EDRE therapy by preserving the integrity of iBRB. This comprehensive strategy also provided a reasonable way to reveal the multi-components, multi-targets, multi-pathways mechanism of TCM.

HIF-1α serves as a co-linker between AD and T2DM

Alzheimer's disease (AD)-related brain deterioration is linked to the type 2 diabetes mellitus (T2DM) features hyperglycemia, hyperinsulinemia, and insulin resistance. Hypoxia as a common risk factor for both AD and T2DM. Hypoxia-inducible factor-1 alpha (HIF-1α) acts as the main regulator of the hypoxia response and may be a key target in the comorbidity of AD and T2DM. HIF-1α expression is closely related to hyperglycemia, insulin resistance, and inflammation. Tissue oxygen consumption disrupts HIF-1α homeostasis, leading to increased reactive oxygen species levels and the inhibition of insulin receptor pathway activity, causing neuroinflammation, insulin resistance, abnormal Aβ deposition, and tau hyperphosphorylation. HIF-1α activation also leads to the deposition of Aβ by promoting the abnormal shearing of amyloid precursor protein and inhibiting the degradation of Aβ, and it promotes tau hyperphosphorylation by activating oxidative stress and the activation of astrocytes, which further exasperates AD. Therefore, we believe that HIF-α has great potential as a target for the treatment of AD. Importantly, the intracellular homeostasis of HIF-1α is a more crucial factor than its expression level.

Transthyretin-Regulated Diabetic Retinopathy Through the VEGFA/PI3K/AKT Pathway

Purpose

Transthyretin (TTR) plays a regulatory role in a variety of diabetes-related diseases. The objective of this work was to probe whether TTR affects diabetic retinopathy (DR) through the VEGFA/PI3K/AKT pathway.

Methods

High glucose (HG, 25 mM) was used to treat human retinal microvascular endothelial cells (hRMECs) and C57BL/6J mice were intraperitoneally injected with STZ (50 mg/kg) to construct a DR model. In vitro, the effect of TTR on DR was evaluated by measuring hRMEC proliferation, migration, and angiogenesis. The changes in retinal tissue were observed by hematoxylin and eosin staining in vivo. ELISA, immunohistochemistry, and immunofluorescence staining were used to measure VEGFA or CD31 levels. The levels of all proteins were evaluated through Western blot.

Results

The increase of proliferation, migration, and angiogenesis and decrease of apoptosis in hRMECs caused by HG were notably reversed by TTR. TTR greatly impeded HG-raised VEGFA, PI3K p-p85, and p-AKT in hRMECs. Inhibition of TTR further exacerbated the effect of HG-induced hRMECs. Inhibition of VEGFA reversed the effect of HG-induced hRMECs. VEGFA neutralized the function of TTR on cell proliferation, apoptosis, migration, and angiogenesis in HG-triggered hRMECs. It was further confirmed in vivo that TTR can alleviate the occurrence of DR in diabetic mice models.

Conclusions

TTR significantly restrained the progression of DR via molecular modulation of the VEGFA/PI3K/AKT axis.

Can Polyherbal Medicine be used for the Treatment of Diabetes? - A Review of Historical Classics, Research Evidence and Current Prevention Programs

Diabetes mellitus (DM), a chronic medical condition, has attained a global pandemic status over the last few decades affecting millions of people. Despite a variety of synthetic drugs available in the market, the use of herbal medicines for managing diabetes is gaining importance because of being comparatively safer. This article reviews the result of a substantial literature search on polyherbal formulations (PHFs) developed and evaluated with potential for DM. The accumulated data in the literature allowed us to enlist 76PHFs consisting of different parts of 147 plant species belonging to 58 botanical families. The documented plant species are laden with bioactive components with anti-diabetic properties and thus draw attention. The most favoured ingredient for PHFs was leaves of Gymnema sylvestre and seeds of Trigonella foenum-graecum used in 27 and 22 formulations, respectively. Apart from herbs, shilajit (exudates from high mountain rocks) formed an important component of 9 PHFs, whereas calcined Mytilus margaritiferus and goat pancreas were used in Dolabi, the most commonly used tablet form of PHF in Indian markets. The healing properties of PHFs against diabetes have been examined in both pre-clinical studies and clinical trials. However, the mechanism(s) of action of PHFs are still unclear and considered the pitfalls inherent in understanding the benefits of PHFs. From the information available based on experimental systems, it could be concluded that plant-derived medicines will have a considerable role to play in the control of diabetes provided the challenges related to their bioavailability, bioefficacy, optimal dose, lack of characterization, ambiguous mechanism of action, and clinical efficiency are addressed.

RAGE plays key role in diabetic retinopathy: a review

RAGE is a multiligand receptor for the immunoglobulin superfamily of cell surface molecules and is expressed in Müller cells, vascular endothelial cells, nerve cells and RPE cells of the retina. Diabetic retinopathy (DR) is a multifactorial disease associated with retinal inflammation and vascular abnormalities and is the leading cause of vision loss or impairment in older or working-age adults worldwide. Therapies aimed at reducing the inflammatory response and unnecessary angiogenesis can help slow the progression of DR, which in turn can save patients' vision. To maximize the efficacy and minimize the side effects, treatments that target key players in the pathophysiological process of DR need to be developed. The interaction between RAGE and its ligands is involved in a variety of cytopathological alterations in the retina, including secretion of inflammatory factors, regulation of angiogenesis, oxidative stress, structural and functional changes, and neurodegeneration. In this review, we will summarize the pathologic pathways mediated by RAGE and its ligand interactions and discuss its role in the progression of diabetic retinopathy to explore potential therapeutic targets that are effective and safe for DR.

Diabetic vascular diseases: molecular mechanisms and therapeutic strategies

Vascular complications of diabetes pose a severe threat to human health. Prevention and treatment protocols based on a single vascular complication are no longer suitable for the long-term management of patients with diabetes. Diabetic panvascular disease (DPD) is a clinical syndrome in which vessels of various sizes, including macrovessels and microvessels in the cardiac, cerebral, renal, ophthalmic, and peripheral systems of patients with diabetes, develop atherosclerosis as a common pathology. Pathological manifestations of DPDs usually manifest macrovascular atherosclerosis, as well as microvascular endothelial function impairment, basement membrane thickening, and microthrombosis. Cardiac, cerebral, and peripheral microangiopathy coexist with microangiopathy, while renal and retinal are predominantly microangiopathic. The following associations exist between DPDs: numerous similar molecular mechanisms, and risk-predictive relationships between diseases. Aggressive glycemic control combined with early comprehensive vascular intervention is the key to prevention and treatment. In addition to the widely recommended metformin, glucagon-like peptide-1 agonist, and sodium-glucose cotransporter-2 inhibitors, for the latest molecular mechanisms, aldose reductase inhibitors, peroxisome proliferator-activated receptor-γ agonizts, glucokinases agonizts, mitochondrial energy modulators, etc. are under active development. DPDs are proposed for patients to obtain more systematic clinical care requires a comprehensive diabetes care center focusing on panvascular diseases. This would leverage the advantages of a cross-disciplinary approach to achieve better integration of the pathogenesis and therapeutic evidence. Such a strategy would confer more clinical benefits to patients and promote the comprehensive development of DPD as a discipline.

Protective effects of Gypenoside XVII against cerebral ischemia/reperfusion injury via SIRT1-FOXO3A- and Hif1a-BNIP3-mediated mitochondrial autophagy

BACKGROUND

Mitochondrial autophagy maintains mitochondrial function and cellular homeostasis and plays a critical role in the pathological process of cerebral ischemia/reperfusion injury (CIRI). Whether Gypenoside XVII (GP17) has regulatory effects on mitochondrial autophagy against CIRI remains unclear. The purpose of this study was to investigate the pharmacodynamic effects and mechanisms of GP17 on mitochondrial autophagy after CIRI.

METHODS

A rat middle cerebral artery occlusion/reperfusion (MCAO/R) model was used to assess the effects of GP17 against CIRI and to explore the underlying mechanisms. An oxygen-glucose deprivation/reoxygenation (OGD/R) cell model was used to verify the ameliorative effects on mitochondrial damage and to probe the autophagy pathways involved in combating neural injuries.

RESULTS

The in vivo results showed that GP17 significantly improved mitochondrial metabolic functions and suppressed cerebral ischemic injury, possibly via the autophagy pathway. Further research revealed that GP17 maintains moderate activation of autophagy under ischemic and OGD conditions, producing neuroprotective effects against CIRI, and that the regulation of mitochondrial autophagy is associated with crosstalk between the SIRT1-FOXO3A and Hif1a-BNIP3 signalling pathway that is partially eliminated by the specific inhibitors AGK-7 and 2-ME.

CONCLUSION

Overall, this work offers new insights into the mechanisms by which GP17 protects against CIRI and highlights the potential of therapy with Notoginseng leaf triterpene compounds as a novel clinical strategy in humans.

Identification of Potential Molecular Targets and Active Ingredients of Mingmu Dihuang Pill for the Treatment of Diabetic Retinopathy Based on Network Pharmacology

Objective. Mingmu Dihuang Pill (MMDHP) is a traditional Chinese formula that has shown remarkable improvements of dry eyes, tearing, and blurry vision; however, the mechanisms underlying MMDHP treatment for diabetic retinopathy have not been fully understood. This study is aimed at identifying the molecular targets and active ingredients of MMDHP for the treatment of diabetic retinopathy based on network pharmacology. Methods. All active ingredients of MMDHP were retrieved from TCMSP and BATMAN-TCM databases, and the targets of active ingredients of MMDHP were predicted on the SwissTargetPrediction website. Diabetic retinopathy-related target sets were retrieved from GeneCards and OMIM databases, and the intersecting targets between targets of active ingredients of MMDHP and potential therapeutic targets of diabetic retinopathy were collected to generate the traditional Chinese medicine-ingredient-target-diabetic retinopathy network and to create the protein-protein interaction network. In addition, GO terms and KEGG pathway enrichment analyses were performed to identify the potential pathways, and molecular docking was employed to verify the binding of active ingredients of MMDHP to key targets of diabetic retinopathy. Results. Network pharmacology predicted 183 active ingredients and 904 targets from MMDHP, and 203 targets were intersected with the therapeutic targets of diabetic retinopathy. The top 10 hub targets included PIK3RA, TP53, SRC, JUN, HRAS, AKT1, VEGFA, EGFR, ESR1, and PI3KCA. GO terms and KEGG pathway enrichment analyses identified AGE-RAGE, PI3K-AKT, and Rap1 signaling pathways as major pathways involved in MMDHP treatment for diabetic retinopathy. Molecular docking confirmed a good binding affinity of active ingredients of MMDHP, including luteolin, acacetin, naringenin, and alisol B, with AKT1, SRC, and VEGFA as the three key targets of diabetic retinopathy. Conclusion. MMDHP may be effective for the treatment of diabetic retinopathy through active ingredients luteolin, acacetin, naringenin, and alisol B via AKT1, SRC, and VEGFA in AGE-RAGE, PI3K-AKT, and Rap1 signaling pathways.

A Mechanistic Exploratory Study on the Therapeutic Efficacy of Astragaloside IV Against Diabetic Retinopathy Revealed by Network Pharmacology

Purpose: Diabetic retinopathy (DR) is a serious complication of diabetes mellitus, which nearly happens to all the diabetic sufferers. This study aims to identify the preliminary molecular regulation involved in the therapeutic efficacy of astragaloside IV (AS- IV) for DR.

Methods: Diabetic rat models were established and treated with AS-IV. Optical coherence tomography (OCT) and Hematoxylin-eosin (HE) staining was employed to demonstrate the histopathological changes. The main targets of AS-IV were identified by searching from public databases of traditional Chinese medicine (GeneCards, PharmMapper and Swiss Target Prediction). Besides, disease targets of DR were also obtained by integrated data from GEO datasets and predicted from public databases. Protein-protein interaction (PPI) network was constructed by Cytoscape with overlapping genes and 10 core targets were selected, on which Gene Ontology (GO) along with Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted. The interaction between AS-IV and these crucial genes were analyzed using molecular docking. RT-qPCR and western blot were used to verify the expression variation of core targets.

Results: OCT imaging and HE staining demonstrated that AS-IV administration significantly increased retinal thickness in diabetic rats, obviously alleviating DR induced histopathological changes as well as elevated blood glucose levels. 107 common targets of AS-IV and DR were determined after intersection. PPI network analysis filtered 10 hub genes potentially targeted by AS-IV, including VEGFA, CASP3, HIF1α, STAT3, CTNNB1, SRC, AKT1, EGFR, IL1β and IL6. Enrichment analysis indicated that these genes were mainly enriched in biological processes like T cell activation, epithelial cell proliferation and protein kinase B signaling, and involved in oxidative stress, apoptosis and inflammation-related pathways. The molecular docking prediction suggested that AS-IV exhibited stable binding to these core targets. In addition, mRNA levels of core targets in diabetic rats were differentially expressed before and after AS-IV treatment. Western blot further revealed that AS-IV treatment elevated DR-depressed protein levels of PI3K and AKT.

Conclusion: Our study elucidated the effect of AS-IV in attenuating retinopathy induced by diabetes in rats and preliminarily unveiled the therapeutic efficacy of AS-IV in the treatment of DR might be attributed to activation of PI3K-AKT signaling pathway.

Lycium barbarum polysaccharides attenuates high glucose-induced diabetic retinal angiogenesis by rescuing the expression of miR-15a-5p in RF/6A cells

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium barbarum L., a classical traditional Chinese Medicine, has long been used to treat ocular diseases. Lycium barbarum polysaccharides (LBP) is an effective component of Lycium barbarum L. with a wide range of pharmacological activities. This research aims to investigate the inhibition of high glucose-induced angiogenesis by LBP in RF/6A cells.

MATERIALS AND METHODS

A high-glucose-induced angiogenesis model was established using monkey retinal vascular endothelial (RF/6A) cells. Different dosages administration times of LBP and glucose concentrations were tested. Under the optimized conditions, RF/6A cells were treated with LBP for 48 h, followed by another 48-h culture in high glucose (25 mmol/L) medium. The effect and mechanism of LBP were investigated following the treatment.

RESULTS

The expression of miR-15a-5p and miR-15a-3p in RF/6A cells decreased significantly after 48 h of 25 or 50 mmol/L high glucose treatment. The expression of miR-15a-5p was higher than that of miR-15a-3p. Mimic-miR-15a-5p or 600 mg/L LBP could increase the apoptosis of cells and the total length of vascular branches. The expression of VEGFA, VEGFR2, and ANG2 proteins was reduced, while the expression of ANG1 protein was elevated. Expression of ASM mRNA and protein was also inhibited.

CONCLUSIONS

LBP attenuates diabetic retinal angiogenesis by rescuing the expression of miR-15a-5p in RF/6A cells.

Investigating the Mechanisms of Pollen Typhae in the Treatment of Diabetic Retinopathy Based on Network Pharmacology and Molecular Docking

OBJECTIVE

To explore the main bioactive compounds and investigate the underlying mechanism of Pollen Typhae (PT) against diabetic retinopathy (DR) by network pharmacology and molecular docking analysis.

METHODS

Bioactive ingredients and the target proteins of PT were obtained from TCMSP, and the related target genes were acquired from the SwissTargetPrediction database. The target genes of DR were obtained from GeneCards, TTD database, DisGeNET database, and DrugBank. The compound-target interaction network was established based on Cytoscape 3.7.2. The protein-protein interaction (PPI) network was constructed via STRING database and Cytoscape 3.7.2. Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were visualized through DAVID database and Bioinformatics. Ingredient-gene-pathway network analysis was conducted to further screen the ingredients, target proteins, and pathways closely related to the biological mechanism on PT for DR, and molecular docking analysis was performed by SYBYL-X 2.1.1 software. Finally, the mechanism and underlying targets of PT in the treatment of DR were predicted.

RESULTS

A total of 8 compounds and 171 intersection targets were obtained based on the online network database. 7 main compounds were screened from compound-target network, and 53 targets including the top six key targets (PTGS2, AKT1, VEGFA, MAPK3, TNF, and EGFR) were further acquired from PPI analysis. The 53 key targets covered 80 signaling pathways, among which PI3K-Akt signaling pathway, focal adhesion, Rap1 signaling pathway, VEGF signaling pathway, and HIF-1 signaling pathway were closely connected with the biological mechanism involved in the alleviation of DR by PT. Ingredient-gene-pathway network shows that AKTI, EGFR, and VEGFA were core genes, kaempferol and isorhamnetin were pivotal ingredients, and VEGF signaling pathway and Rap1 signaling pathway were closely involved in anti-DR. The docking results indicated that five main compounds (arachidonic acid, isorhamnetin, quercetin, kaempferol, and (2R)-5,7-dihydroxy-2-(4-hydroxyphenyl)chroman-4-one) had good binding activity with EGFR and AKT1 targets.

CONCLUSION

The active ingredients in PT may regulate the levels of inflammatory factors, suppress the oxidative stress, and inhibit the proliferation, migration, and invasion of retinal pericytes by acting on PTGS2, AKT1, VEGFA, MAPK3, TNF, and EGFR targets through VEGF signaling pathway, PI3K-Akt signaling pathway, Rap1 signaling pathway, and HIF-1 signaling pathway to play a therapeutic role in diabetic retinopathy.

Role of pyroptosis in diabetic retinopathy and its therapeutic implications

Pyroptosis has recently been established as a term of programmed-inflammatory cell death. Pyroptosis is mainly divided into two molecular signaling pathways, including caspase-1-dependent canonical and caspase-4/5/11-dependent non-canonical inflammasome pathways. Extensive investigations have reported inflammasome activation facilitates the maturation and secretion of the inflammatory factors interleukin-1β/18 (IL-1β/18), cleavage of gasdermin D (GSDMD), and leading to the stimulation of pyroptosis-mediated cell death. Furthermore, accumulating studies report NLRP3 inflammasome activation plays a significant role in triggering the pyroptosis-mediated cell death and promotes the pathogenesis of diabetic retinopathy (DR). Our current review elaborates on the molecular mechanisms of pyroptosis-signaling pathways and their potential roles in the pathogenesis and impact of DR development. We also emphasize several investigational molecules regulating key steps in pyroptotic-cell death to create new comprehensions and findings to explore the pathogenesis of DR advancement. Our narrative review concisely suggests these potential pharmacological agents could be promising therapies to treat and manage DR in the future.

Mangiferin inhibits cell migration and angiogenesis via PI3K/AKT/mTOR signaling in high glucose‑ and hypoxia‑induced RRCECs

Mangiferin is a prominent active component that can be derived from several traditional herbs, including Mangifera indica L., Anemarrhena asphodeloides Bge., and Belamcanda chinensis (L.) DC., which displays antidiabetic properties. Diabetic retinopathy (DR), a serious complication caused by diabetes, is the leading cause of blindness. The present study aimed to evaluate the beneficial effects of mangiferin on high glucose (HG)/hypoxia‑induced rat retinal capillary endothelial cell (RRCEC) angiogenesis, as well as the underlying mechanisms. To establish an in vitro model of DR, RRCECs were exposed to 30 mM glucose and hypoxia. Following treatment with different doses of mangiferin (0.05, 0.1 or 0.2 µM), RRCEC viability, migration and angiogenesis were assessed by performing Cell Counting Kit 8, immunofluorescence, wound healing, Transwell and tube formation assays. Western blotting was conducted to evaluate protein expression levels. Furthermore, LY294002 and IGF‑1, an inhibitor and activator of the PI3K/AKT/mTOR signaling pathway, respectively, were used to verify the potential mechanisms underlying mangiferin. The results demonstrated that mangiferin notably inhibited HG/hypoxia‑induced RRCEC migration and angiogenesis. HG/hypoxia‑induced upregulation of hypoxia‑inducible factor‑1α, vascular endothelial growth factor, matrix metallopeptidase (MMP)2 and MMP9 expression levels and the phosphorylation of PI3K, AKT and mTOR in RRCECs was significantly reversed following treatment with mangiferin. Additionally, further activation of the PI3K/AKT signaling pathway by IGF‑1 inhibited the beneficial effects of mangiferin on RRCECs, whereas deactivation of the PI3K/AKT signaling pathway by LY294002 displayed the opposite results. Collectively, the results of the present study suggested that mangiferin suppressed RRCEC angiogenesis via modulating the PI3K/AKT/mTOR signaling pathway, which could serve as an effective treatment strategy for DR.

Gambogic acid ameliorates high glucose- and palmitic acid-induced inflammatory response in ARPE-19 cells via activating Nrf2 signaling pathway: ex vivo

Diabetic retinopathy (DR) is a serious microvascular complication of diabetes. Gambogic acid has been reported to have anti-inflammatory effect. However, the effect of GA on inflammatory response of ARPE-19 cells remains unclear. In our study, ARPE-19 cells were stimulated by palmitic acid (PA) induction in the presence of 30 mM glucose and then treated with 0.5, 1, 2, 5, 10, or 20 μM GA. CCK-8 assay showed that cell viability was increased by GA treatment at doses of 0.5, 1, and 2 μM instead of higher doses. ELISA analysis found that GA dose-dependently reduced the production of pro-inflammatory mediators TNF-α and IL-1β. Western blot indicated that GA downregulated the expression of NLRP3 inflammasome components including TXNIP, NLRP3, ASC, cleaved-caspase-1, and cleaved-IL-1β in a dose-dependent manner. In addition, Western blot and immunofluorescence analysis suggested that GA effectively increased the protein level of nuclear factor E2-related factor-2 (Nrf2). RT-qPCR showed that GA significantly increased the mRNA levels of Heme oxygenase-1 (HO-1) and NADPH:quinone oxidoreductase1 (NQO1). Furthermore, Nrf2 siRNA transfection confirmed the above effects of GA. In total, subtoxic doses of GA significantly flattened the inflammatory response induced by HG and PA in ARPE-19 cells via modulating the Nrf2 signaling pathway.

Upregulation of long non-coding RNA SNHG16 promotes diabetes-related RMEC dysfunction via activating NF-κB and PI3K/AKT pathways

Diabetic retinopathy (DR) is a severe diabetes-induced eye disease, in which its pathological phenomena basically include abnormal proliferation, migration, and angiogenesis of microvascular endothelial cells in the retina. Long non-coding RNAs (lncRNAs) have been proven to be important regulators in various biological processes, but their participation in DR remains largely undiscovered. In the present study, we aimed to unveil the role of lncRNA small nucleolar RNA host gene 16 (SNHG16) in regulating the functions of human retinal microvascular endothelial cells (hRMECs) under a high-glucose (HG) condition. We found that SNHG16 expression was significantly upregulated in hRMECs treated with HG. Functionally, SNHG16 could facilitate hRMEC proliferation, migration, and angiogenesis. Moreover, SNHG16 was associated with nuclear factor κB (NF-κB) and phosphatidylinositol 3-kinase (PI3K)/AKT pathways. Mechanistically, SNHG16 could promote hRMEC dysfunction by sequestering microRNA (miR)-146a-5p and miR-7-5p to act as a competing endogenous RNA (ceRNA) with interleukin-1 receptor-associated kinase 1 (IRAK1) and insulin receptor substrate 1 (IRS1). In conclusion, our results illustrated the potential role of SNHG16 in facilitating hRMEC dysfunction under HG treatment, providing a novel approach for DR therapy.

A Deep Learning-Based Approach for Identifying the Medicinal Uses of Plant-Derived Natural Compounds

Medicinal plants and their extracts have been used as important sources for drug discovery. In particular, plant-derived natural compounds, including phytochemicals, antioxidants, vitamins, and minerals, are gaining attention as they promote health and prevent disease. Although several in vitro methods have been developed to confirm the biological activities of natural compounds, there is still considerable room to reduce time and cost. To overcome these limitations, several in silico methods have been proposed for conducting large-scale analysis, but they are still limited in terms of dealing with incomplete and heterogeneous natural compound data. Here, we propose a deep learning-based approach to identify the medicinal uses of natural compounds by exploiting massive and heterogeneous drug and natural compound data. The rationale behind this approach is that deep learning can effectively utilize heterogeneous features to alleviate incomplete information. Based on latent knowledge, molecular interactions, and chemical property features, we generated 686 dimensional features for 4,507 natural compounds and 2,882 approved and investigational drugs. The deep learning model was trained using the generated features and verified drug indication information. When the features of natural compounds were applied as input to the trained model, potential efficacies were successfully predicted with high accuracy, sensitivity, and specificity.

Normal vitreous promotes angiogenesi via the epidermal growth factor receptor

Vitreous, a transparent tissue in our body, contains anti-angiogenesis factors. Our previous work reported that vitreous activates the signaling pathway of epidermal growth factor receptor (EGFR), which plays a critical role in angiogenesis. The aim of this study was to determine the role of EGFR in vitreous-induced angiogenesis-related cellular responses in vitro. Using a pharmacologic and molecular approach, we found that vitreous increased proliferation and migration via EGFR in human umbilical vein endothelial cells (HUVECs). Furthermore, we demonstrated that vitreous promoted tube formation via EGFR in HUVECs. Subsequently, depletion of EGFR using CRISPR/Cas9 and blockage with EGFR inhibitor AG1478 suppressed vitreous-induced Akt activation and cell proliferation, migration, and tube formation in HUVECs. The significance of the angiogenic effect derived from vitreous demonstrates the importance of vitreous in the ocular physiology and the pathobiology of angiogenesis-related ophthalmic diseases, such as proliferative diabetic retinopathy.

Hypoxia-inducible factor-1α: A promising therapeutic target for vasculopathy in diabetic retinopathy

Diabetic retinopathy (DR) is a serious condition that can cause blindness in diabetic patients. It is a neurovascular disease, but the pathogenesis leading to the onset of this disease is still not completely understood. However, hypoxia with subsequent neovascularization is a characteristic phenomenon observed with DR. Cellular response to hypoxia is mediated by the transcriptional regulator hypoxia-inducible factor (HIF). Long-term research has shown that one isotype of HIF, HIF-1α, may play a pivotal role under hypoxic conditions, and an increasing number of studies have shown that HIF-1α and its target genes contribute to retinal neovascularization. Therefore, targeting HIF-1α may lead to more effective DR treatments. This review describes the possible mechanisms of HIF-1α in neovascularization of DR. Furthermore, various inhibitors of HIF-1α that may have viable potential in the treatment of DR are also discussed.

Ginsenoside Re Attenuates High Glucose-Induced RF/6A Injury via Regulating PI3K/AKT Inhibited HIF-1α/VEGF Signaling Pathway

Hyperglycaemia-induced retinal microvascular endothelial cell apoptosis is a critical and principle event in diabetic retinopathy (DR), which involves a series of complex processes such as mitochondrial dysfunction and oxidative stress. Ginsenoside Re (Re), a key ingredients of ginseng, is considered to have various pharmacologic functions, such as antioxidative, inhibition of inflammation and anti-apoptotic properties. However, the effects of Re in DR and the related mechanisms of endothelial cell injury induced by high glucose (HG) exposure remain unclear. The present study was designed to investigate and evaluate the ability of Re to ameliorate HG-induced retinal endothelial RF/6A cell injury and the potential mechanisms involved in the hypoxia-inducible factor-1-alpha (HIF-1α)/vascular endothelial growth factor (VEGF) signaling regulated by phosphoinositide 3-kinase (PI3K)/AKT pathway. Our results showed that preincubation with Re exerted cytoprotective effects by reversing the HG-induced decrease in RF/6A cell viability, downregulation of apoptosis rate and inhibition of oxidative-related enzymes, thereby reducing the excess intracellular reactive oxygen species (ROS) and HG-triggered RF/6A cell injury. In addition, Western blot analysis results showed ginsenoside Re significantly increased HIF-1α expression in the cytoplasm but decreased its expression in the nucleus, suggesting that it reduced the translocation of HIF-1α from the cytoplasm to the nucleus, and downregulated VEGF level. Moreover, this effect is involved in the activation of the PI3K/Akt pathway. LY294002, a PI3K inhibitor, was used to block the Akt pathway. Afterwards, the effects of Re on the regulation of apoptotic related proteins, VEGF and HIF-1α nuclear transcription was partially reversed. These findings suggested the exerting protective effects of ginsenoside Re were associated with regulating of PI3K/AKT and HIF-1α/VEGF signaling pathway, which indicates that ginsenoside Re may ameliorates HG-induced retinal angiogenesis and suggests the potential for the development of Re as a therapeutic for DR.

Spalt-Like Protein 4 (SALL4) Promotes Angiogenesis by Activating Vascular Endothelial Growth Factor A (VEGFA) Signaling

Background

Spalt-like protein 4 (SALL4) is a nuclear transcription factor central to early embryonic development, especially for regulating pluripotency of embryonic stem cells (ESCs) and sustaining ESCs self-renewal. Aberrant re-expression of SALL4 in adult tissues is involved in tumorigenesis and cancer progression. However, the role of SALL4 in angiogenesis remains elusive. Here, we determined the potential action of SALL4 on proliferation, migration, and tube formation of endothelial cells.

Material/Methods

HUVECs were infected with lentiviral particles expressing shRNA against SALL4. QRT-PCR and immunoblotting analysis were carried out to evaluate knockdown efficiency at mRNA and protein levels. Cell proliferation was measured by CCK-8 assay and flow cytometry was conducted to analyze cell cycle distribution. Wound-healing and Transwell migration assays were performed to evaluate cell motility. In addition, we determined the role of SALL4 on angiogenesis by tube formation assay, and Western blot analysis was used to assess the effect of SALL4 downregulation on VEGFA expression.

Results

We found that SALL4 downregulation resulted in decreased proliferation. Cell cycle analysis revealed that SALL4 knockdown impeded cell cycle progression and induced cell cycle arrest at G1 phase. We also found that silencing of SALL4 decreased the capacity of wound healing and cell migration in HUVECs. Furthermore, tube formation assay showed that loss of SALL4 inhibited HUVECs angiogenesis. We also observed that SALL4 knockdown reduced the level of VEGFA in HUVECs.

Conclusions

In conclusion, these results support that by promoting proliferation, cell cycle progression, migration, and tube formation, SALL4 is involved in the process of angiogenesis through modulating VEGFA expression.

Gambogic acid exhibits anti-metastatic activity on malignant melanoma mainly through inhibition of PI3K/Akt and ERK signaling pathways

Gambogic acid (GA) is a potential anti-cancer compound that is extracted from the resin of Garciania hanburyi. The present study was designed to evaluate the anti-metastatic effect of GA on melanoma cell lines in vitro and to explore the underlying mechanism. The anti-proliferative activity of GA on melanoma cells was assessed by CCK-8 assay. The Wound-healing, transwell, adhesion, and tube formation assays were performed to examine the inhibition of GA on the cell's migration, invasion, adhesion, and angiogenesis capacities, respectively. Enzymatic activity of MMP-2 and MMP-9 were detected by gelatin zymography assay. Protein expressions regulated by GA treatment were tested by Western blot assay. The present results showed that GA significantly inhibited the proliferation of highly metastatic melanoma A375, B16-F10 cells and human umbilical vein endothelial cells (HUVECs) in time- and doses-dependent manners. Furthermore, GA significantly inhibited the migratory, invasive and adhesive properties of A375 and B16-F10 cells, and tube-forming potential of HUVECs at sub-IC50 concentrations, where no significant cytotoxicity was observed. Mechanistically, GA treatment suppressed the EMT and angiogenesis processes and reduced the enzymatic activity of MMP-2 and MMP-9. Moreover, abnormal PI3K/Akt and ERK signaling pathways in A375 and B16-F10 cells and HUVECs were notably suppressed by GA treatment. Collectively, our results suggest that GA exerts anti-metastasis activity in melanoma cells by suppressing the EMT and angiogenesis through the PI3K/Akt and ERK signaling pathways, and might be used as a phytomedicine against metastatic melanoma.

Anil Kumar N, Sharopov F, Ramírez-Alarcón K, Ruiz-Ortega A, Abdulmajid Ayatollahi S, Valere Tsouh Fokou P, Kobarfard F, Amiruddin Zakaria Z, Iriti M, Taheri Y, Martorell M, Sureda A, N. Setzer W, Durazzo A, Lucarini M, Santini A, Capasso R, Adrian Ostrander E, -ur-Rahman A, Iqbal Choudhary M, C. Cho W, Sharifi-Rad J. Antidiabetic Potential of Medicinal Plants and Their Active Components

Diabetes mellitus is one of the major health problems in the world, the incidence and associated mortality are increasing. Inadequate regulation of the blood sugar imposes serious consequences for health. Conventional antidiabetic drugs are effective, however, also with unavoidable side effects. On the other hand, medicinal plants may act as an alternative source of antidiabetic agents. Examples of medicinal plants with antidiabetic potential are described, with focuses on preclinical and clinical studies. The beneficial potential of each plant matrix is given by the combined and concerted action of their profile of biologically active compounds.

Müller cells in pathological retinal angiogenesis

Müller cells are the major glial cells spanning the entire layer of the retina and maintaining retinal structure. Under pathological conditions, Müller cells are involved in retinal angiogenesis, a process of growing new blood vessels from pre-existing capillaries. In response to hypoxia, high glucose, and inflammation conditions, multiple signaling pathways are activated in Müller cells, followed by the increased production of proangiogenic factors including vascular endothelial growth factor, basic fibroblast growth factor, matrix metalloproteinases, Netrin-4, and angiopoietin-like 4. Expression of antiangiogenic factors is also downregulated in Müller cells. Besides, proliferation and dedifferentiation of Müller cells facilitates retinal angiogenesis. In this review, we summarized molecular mechanisms of Müller cells-related retinal angiogenesis. The potential of Müller cells as a therapeutic target for retinal angiogenesis was also discussed.

Cinobufagin suppresses colorectal cancer angiogenesis by disrupting the endothelial mammalian target of rapamycin/hypoxia-inducible factor 1α axis

Inducing angiogenesis is a hallmark of cancers that sustains tumor growth and metastasis. Neovascularization is a surprisingly early event during the multistage progression of cancer. Cinobufagin, an important bufadienolide originating from Chan Su, has been clinically used to treat cancer in China since the Tang dynasty. Here, we show that cinobufagin suppresses colorectal cancer (CRC) growth in vivo by downregulating angiogenesis. The hierarchized neovasculature is significantly decreased and the vascular network formation is disrupted in HUVEC by cinobufagin in a dose‐dependent way. Endothelial apoptosis is observed by inducing reactive oxygen species (ROS) accumulation and mitochondrial dysfunction which can be neutralized by N‐acetyl‐l‐cysteine (NAC). Expression of hypoxia‐inducible factor 1α (HIF‐1α) is reduced and phosphorylation of mTOR at Ser2481 and Akt at Ser473 is downregulated in HUVEC. Endothelial apoptosis is triggered by cinobufagin by stimulation of Bax and cascade activation of caspase 9 and caspase 3. Increased endothelial apoptosis rate and alterations in the HIF‐1α/mTOR pathway are recapitulated in tumor‐bearing mice in vivo. Further, the anti‐angiogenesis function of cinobufagin is consolidated based on its pro‐apoptotic effects on an EOMA‐derived hemangioendothelioma model. In conclusion, cinobufagin suppresses tumor neovascularization by disrupting the endothelial mTOR/HIF‐1α pathway to trigger ROS‐mediated vascular endothelial cell apoptosis. Cinobufagin is a promising natural anti‐angiogenetic drug that has clinical translation potential and practical application value.

To Explore the Pathogenesis of Vascular Lesion of Type 2 Diabetes Mellitus Based on the PI3K/Akt Signaling Pathway

BACKGROUND

Type 2 diabetes mellitus (T2DM) has become a chronic disease, serious harm to human health. Complications of the blood pipe are the main cause of disability and death in diabetic patients, including vascular lesions that directly affects the prognosis of patients with diabetes and survival. This study was to determine the influence of high glucose and related mechanism of vascular lesion of type 2 diabetes mellitus pathogenesis.

METHODS

In vivo aorta abdominalis of GK rats was observed with blood pressure, heart rate, hematoxylin and eosin (H&E), Masson, and Verhoeff staining. In vitro cells were cultured with 30 mM glucose for 24 h. RT-QPCR was used to detect the mRNA expression of endothelial markers PTEN, PI3K, Akt, and VEGF. Immunofluorescence staining was used to detect the expression of PTEN, PI3K, Akt, and VEGF. PI3K and Akt phosphorylation levels were detected by Western blot analysis.

RESULTS

Heart rate, systolic blood pressure, diastolic blood pressure, and mean blood pressure in the GK control group were higher compared with the Wistar control group and no difference compared with the GK experimental model group. Fluorescence intensity of VEGF, Akt, and PI3K in the high-sugar stimulus group was stronger than the control group; PTEN in the high-sugar stimulus group was weakening than the control group. VEGF, Akt, and PI3K mRNA in the high-sugar stimulus group were higher than the control group; protein expressions of VEGF, Akt, and PI3K in the high-sugar stimulus group were higher than the control group. PTEN mRNA in the high-sugar stimulus group was lower than the control group. Protein expression of PTEN in the high-sugar stimulus group was lower than the control group.

CONCLUSIONS

Angiogenesis is an important pathogenesis of T2DM vascular disease, and PTEN plays a negative regulatory role in the development of new blood vessels and can inhibit the PI3K/Akt signaling pathway.

Activation of the sweet taste receptor T1R3 by sucralose attenuates VEGF-induced vasculogenesis in a cell model of the retinal microvascular endothelium

BACKGROUND

One of the most prevalent microvascular complications for patients with diabetes is diabetic retinopathy (DR) associated with increased retinal endothelial blood vessel formation. Treatments to reduce vascularisation in the retinal endothelium are linked to improved sight in patients with DR. Recently, we have demonstrated the novel protective role of the artificial sweetener, sucralose, and the sweet taste receptor, T1R3, in the pulmonary endothelium to reduce vascular leak. In the present study, we examined the role of sucralose and sweet taste receptors on vasculogenic processes (proliferation, migration, adhesion and tube formation) in a cell model of the retinal endothelium.

METHODS

We exposed human retinal microvascular endothelial cells (RMVEC) to VEGF as an in vitro model of DR in the presence and absence of T1R3 agonist sucralose.

RESULTS

In RMVEC, we observed increased VEGF-induced cell proliferation, migration, adhesion and tube formation, which was significantly attenuated by exposure to the artificial sweetener sucralose. Following siRNA knockdown of the sweet taste receptor, T1R3, but not T1R2, the protective effect of sucralose on VEGF-induced RMVEC vasculogenic processes was blocked. We further demonstrate that sucralose attenuates VEGF-induced Akt phosphorylation to protect the retinal microvasculature.

CONCLUSION

These studies are the first to demonstrate a protective effect of an artificial sweetener, through the sweet taste receptor T1R3, on VEGF-induced vasculogenesis in a retinal microvascular endothelial cell line.

Alterations in the polysialylated neural cell adhesion molecule and retinal ganglion cell density in mice with diabetic retinopathy

AIM

To investigate the impact of polysialylated neural cell adhesion molecule (PSA-NCAM) on the survival of retinal ganglion cells (RGCs) in the experimentally induced diabetes in mice.

METHODS

Diabetes was induced in 2.5 months old Swiss Webster mice by intraperitoneal injection of streptozotocin (STZ, 90 mg/kg) once daily for two consecutive days. Examination of the proteins of interest in the retinas from diabetic mice at 2mo after diabetes induction was performed using immunohistochemistry and Western blot analysis. RGCs were counted in the wholemounted retinas, and Brn3a marker was used.

RESULTS

Examination of retinas from diabetic mice at 2mo after diabetes induction revealed a considerable reduction in RGC density. Our experiments also demonstrated a redistribution of PSA-NCAM in the retina of diabetic animals. PSA-NCAM immunoreactivity was diminished in the inner part of the retina where RGCs were located. In contrast, an enhanced PSA-NCAM immunoreactivity was detected in the outer layers of the retina. PSA-NCAM signal was co-localized with glial fibrillary acidic protein immunoreactivity in the Müller cell branches. Previous studies have shown that matrix metalloproteinase-9 (MMP-9) is responsible for the reduction in PSA-NCAM levels in neuronal cells. The reduced levels of PSA-NCAM in inner layers (nerve fiber layer, ganglion cell layer) were accompanied by the increased expression of MMP-9. In contrast, in the outer retinal layers, the expression of MMP-9 was much less pronounced.

CONCLUSION

MMP-9 induces PSA-NCAM shedding in the inner part of the retina and the decreased level of PSA-NCAM in the inner part of the retina might be, at least in part, responsible for the loss of RGCs in diabetic mice.