Tangeretin Inhibition of High-Glucose-Induced IL-1β, IL-6, TGF-β1, and VEGF Expression in Human RPE Cells

Machine Learning-Driven Identification of Hematological and Immunological Biomarkers for Predicting Proliferative Diabetic Retinopathy Progression

PURPOSE

Proliferative Diabetic Retinopathy (PDR) is a severe complication of diabetes characterized by neovascularization and retinal detachment, leading to significant vision loss. This study investigates the predictive power of hematological and immunological markers in PDR progression.

METHODS

Data from 126 patients were analyzed using advanced machine learning techniques, including LASSO regression, elastic net modeling, and backward stepwise regression.

RESULTS

The findings identified age, gender, IL-1, and lymphocyte count (LYM) as significant predictors of PDR, with a high AUC value of 0.839 from the ROC curve analysis. These markers, particularly cytokines in the aqueous humor and peripheral blood, offer a convenient and rapid method for early detection and risk assessment of PDR.

CONCLUSIONS

Despite the limitations of being a cross-sectional study with a relatively small sample size, the results highlight the clinical significance of these biomarkers and underscore the need for further validation in larger, more diverse populations. This study contributes to the development of targeted interventions and improved management strategies for diabetic retinopathy, emphasizing the importance of immunological health in disease progression.

Knockdown of HOTAIR Alleviates High Glucose-Induced Apoptosis and Inflammation in Retinal Pigment Epithelial Cells

Diabetic retinopathy (DR) is one of the most common microvascular complications in diabetes. Accumulating evidence demonstrated that long non-coding RNAs (lncRNAs) played critical regulatory roles in DR. However, the role of lncRNA HOX Transcript Antisense Intergenic RNA (HOTAIR) in the high glucose (HG)-induced human retinal pigment epithelial (RPE) cell injury remains unclear. Herein, we found the expression of HOTAIR was increased in the retina of DR rats and HG-induced ARPE-19 cells. Knockdown of HOTAIR improved viability, inhibited apoptosis, increased Bcl-2 protein levels, and decreased Bax and cleaved caspase 3 protein levels in HG-treated ARPE-19 cells. Moreover, enzyme-linked immunosorbent assay showed that HOTAIR silencing reduced interleukin 6 and tumor necrosis factor-α release of ARPE-19 cells under HG conditions. Mechanistically, luciferase reporter assay and RNA immunoprecipitation assay validated that HOTAIR could directly sponge miR-326 to upregulate transcription factor 4 (TCF4) expression. Furthermore, rescue experiments confirmed that HOTAIR promoted apoptosis and inflammation of HG-treated ARPE-19 cells by the miR-326/TCF4 axis. In summary, HOTAIR enhanced HG-induced retinal pigment epithelial cell injury by promoting apoptosis and inflammation, shedding light on the importance of HOTAIR as a novel potential target for DR treatment.

Sea buckthorn flavonoids protect RPE cells from UVB-induced oxidative damage

Natural flavonoids are believed to provide protection to retinal pigment epithelial (RPE) cells due to their well-established antioxidant properties. This study aims to evaluate the impact of sea buckthorn flavonoids on a UVB-induced oxidative damage model of RPE cells. The n-butanol extract fraction (Fr. NB) was identified as the most effective component from five different polar extracts using the ABTS method and an RPE cell oxidative stress model. Interestingly, HPLC analysis revealed that the main flavonoids in Fr. NB were rutin, Isorhamnetin-3-O-glucoside-7-O-rhamnoside (IR3G7R), and Isorhamnetin-3-O-glucoside (IR3G), all of which significantly increased cell viability. Both Fr. NB and the major flavonoids reduced oxidative damage by enhancing the activity of antioxidant enzymes and reducing levels of oxidative products and apoptosis. These findings suggest that sea buckthorn flavonoids may protect RPE cells from UVB-induced oxidative damage through an antioxidant mechanism, potentially offering health benefits for the human eye.

Ethyl Acetate Fractions of Salvia miltiorrhiza Bunge (Danshen) Crude Extract Modulate Fibrotic Signals to Ameliorate Diabetic Kidney Injury

Diabetic nephropathy, a leading cause of end-stage renal disease, accounts for significant morbidity and mortality. It is characterized by microinflammation in the glomeruli and myofibroblast activation in the tubulointerstitium. Salvia miltiorrhiza Bunge, a traditional Chinese medicine, is shown to possess anti-inflammatory and anti-fibrotic properties, implying its renal-protective potential. This study investigates which type of component can reduce the damage caused by diabetic nephropathy in a single setting. The ethyl acetate (EtOAc) layer was demonstrated to provoke peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ activities in renal mesangial cells by dual luciferase reporter assay. In a high glucose (HG)-cultured mesangial cell model, the EtOAc layer substantially inhibited HG-induced elevations of interleukin-1β, transforming growth factor-β1 (TGF-β1), and fibronectin, whereas down-regulated PPAR-γ was restored. In addition, among the extracts of S. miltiorrhiza, the EtOAc layer effectively mitigated TGF-β1-stimulated myofibroblast activation. The EtOAc layer also showed a potent ability to attenuate renal hypertrophy, proteinuria, and fibrotic severity by repressing diabetes-induced proinflammatory factor, extracellular matrix accumulation, and PPAR-γ reduction in the STZ-induced diabetes mouse model. Our findings, both in vitro and in vivo, indicate the potential of the EtOAc layer from S. miltiorrhiza for future drug development targeting diabetic nephropathy.

Liraglutide prevents cellular senescence in human retinal endothelial cells (HRECs) mediated by SIRT1: an implication in diabetes retinopathy

Diabetes mellitus (DM) is a chronic metabolic disorder affecting millions of people worldwide, characterized by dysregulated glucose homeostasis and hyperglycemia. Diabetic retinopathy (DR) is one of the serious multisystemic complications. Aging is an important risk factor for DR. Endothelial sirtuin 1 (SIRT1) plays an important role in regulating the pathophysiology of glucose metabolism, cellular senescence, and aging. Liraglutide, an analog of Glucagon-like peptide 1 (GLP-1), has been widely used in the treatment of DM. However, the effects of Liraglutide on DR are less reported. Here, we investigated whether treatment with Liraglutide has beneficial effects on high glucose (HG)-induced injury in human retinal microvascular endothelial cells (HRECs). First, we found that exposure to HG reduced the expression of glucagon-like peptide 1 receptor 1 (GLP-1R). Additionally, Liraglutide ameliorated HG-induced increase in the expression of vascular endothelial growth factor-A (VEGF-A) and interleukin 6 (IL-6). Importantly, Liraglutide ameliorated cellular senescence and increased telomerase activity in HG-challenged HRECs. Liraglutide also reduced the levels of p53 and p21. Mechanistically, Liraglutide restored the expression of SIRT1 against HG. In contrast, the knockdown of SIRT1 abolished the protective effects of Liraglutide in cellular senescence of HRECs. Our findings suggest that Liraglutide might possess a benefit on DR mediated by SIRT1.

Mechanistic insights into the alterations and regulation of the AKT signaling pathway in diabetic retinopathy

In the early stages of diabetic retinopathy (DR), diabetes-related hyperglycemia directly inhibits the AKT signaling pathway by increasing oxidative stress or inhibiting growth factor expression, which leads to retinal cell apoptosis, nerve proliferation and fundus microvascular disease. However, due to compensatory vascular hyperplasia in the late stage of DR, the vascular endothelial growth factor (VEGF)/phosphatidylinositol 3 kinase (PI3K)/AKT cascade is activated, resulting in opposite levels of AKT regulation compared with the early stage. Studies have shown that many factors, including insulin, insulin-like growth factor-1 (IGF-1), VEGF and others, can regulate the AKT pathway. Disruption of the insulin pathway decreases AKT activation. IGF-1 downregulation decreases the activation of AKT in DR, which abrogates the neuroprotective effect, upregulates VEGF expression and thus induces neovascularization. Although inhibiting VEGF is the main treatment for neovascularization in DR, excessive inhibition may lead to apoptosis in inner retinal neurons. AKT pathway substrates, including mammalian target of rapamycin (mTOR), forkhead box O (FOXO), glycogen synthase kinase-3 (GSK-3)/nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear factor kappa-B (NF-κB), are a research focus. mTOR inhibitors can delay or prevent retinal microangiopathy, whereas low mTOR activity can decrease retinal protein synthesis. Inactivated AKT fails to inhibit FOXO and thus causes apoptosis. The GSK-3/Nrf2 cascade regulates oxidation and inflammation in DR. NF-κB is activated in diabetic retinas and is involved in inflammation and apoptosis. Many pathways or vital activities, such as the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) and mitogen-activated protein kinase (MAPK) signaling pathways, interact with the AKT pathway to influence DR development. Numerous regulatory methods can simultaneously impact the AKT pathway and other pathways, and it is essential to consider both the connections and interactions between these pathways. In this review, we summarize changes in the AKT signaling pathway in DR and targeted drugs based on these potential sites.

Wnt inhibitory factor 1 ameliorated diabetic retinopathy through the AMPK/mTOR pathway-mediated mitochondrial function

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus and will lead to visual impairment. We aim to explore the effects and mechanisms of wnt inhibitory factor 1 (WIF1) in the progression of DR. To establish DR in vitro and in vivo, human retinal pigment epithelium (RPE) cell line ARPE-19 was treated with high-glucose (HG) and diabetic mice models were induced by streptozotocin (STZ), respectively. Different dose of recombinant WIF1 protein was used to treat DR. qRT-PCR and western blotting results demonstrated that WIF1 was downregulated, while VEGFA was upregulated in HG-induced ARPE-19 cells. WIF1 overexpression promoted cell migration. The ARPE-19 cells culture medium treated with WIF1 inhibited retinal endothelial cell tube formation and downregulated VEGFA expression. Moreover, WIF1 decreased the levels of ROS and MDA, while increasing the activity of SOD and GPX. WIF1 increased the ΔΨm in the mitochondria and downregulated the expression of mitochondrial autophagy-related proteins including Parkin, Pink1, LC3-II/LC3-I ratio, cleaved caspase 3, and cyt-c, which ameliorated mitochondrial dysfunction. The in vivo studies further demonstrated the consistent effects of WIF1 in STZ-induced mice. Taken together, WIF1 ameliorated mitochondrial dysfunction in DR by downregulating the AMPK/mTOR pathway.

Identifying Active Compounds and Mechanisms of Citrus changshan-Huyou Y. B. Chang against URTIs-Associated Inflammation by Network Pharmacology in Combination with Molecular Docking

Purpose. The ripe fruits of Citrus changshan-huyou, known as Quzhou Fructus Aurantii (QFA), have been commonly used for respiratory diseases. The purpose of this study was to investigate their active compounds and demonstrate their mechanism in the treatment of upper respiratory tract infections (URTIs) through network pharmacology and molecular docking. Methods. The prominent compounds of QFA were acquired from TCMSP database. Their targets were retrieved from SwissTargetPrediction database, and target genes associated with URTIs were collected from DisGeNET and GeneCards databases. The target protein-protein interaction (PPI) network was constructed by using STRING database and Cytoscape. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were enriched. Visual compound-target-pathway network was established with Cytoscape. The effects of compounds were verified on the inhibitory activities against phosphoinositide 3-kinases (PI3Ks). Finally, the molecular docking was carried out to confirm the binding affinity of the bioactive compounds and target proteins. Results. Five important active compounds, naringenin (NAR), tangeretin (TAN), luteolin (LUT), hesperetin (HES), and auraptene (AUR), were obtained. The enrichment analysis demonstrated that the pathways associated with inflammation mainly contained PI3K/Akt signalling pathway, TNF signalling pathway, and so on. The most important targets covering inflammation-related proteins might be PI3Ks. In vitro assays and molecular docking exhibited that TAN, LUT, and AUR acted as PI3Kγ inhibitors. Conclusion. The results revealed that QFA could treat URTIs through a multi-compound, multi-target, multi-pathway network, in which TAN, LUT, and AUR acted as PI3Kγ inhibitors, probably contributing to a crucial role in treatment of URTIs.

Long non‑coding RNA MALAT1 is involved in retinal pigment epithelial cell damage caused by high glucose treatment

The present study aimed to explore the role of long non‑coding RNA metastasis associated lung adenocarcinoma transcript 1 (lncRNA MALAT1) in high glucose (HG)‑induced ARPE‑19 cell damage. ARPE‑19 cells were cultured and treated with HG (25 mmol/l glucose). MALAT1 expression was silenced following transfection of small interfering RNA. Cell apoptosis was measured using flow cytometry. The cellular levels of reactive oxygen species (ROS), malondialdehyde and superoxide dismutase activity were all measured to examine oxidative stress. Gene expression levels of MALAT1 were determined by reverse transcription‑quantitative (RT‑q)PCR, while expression of tumor necrosis factor (TNF)‑α, monocyte chemotactic protein 1 (MCP‑1), intercellular cell adhesion molecule 1 (ICAM‑1) and vascular endothelial growth factor (VEGF) was detected using RT‑qPCR and western blotting. MALAT1 expression was markedly increased in ARPE‑19 cells treated with HG. HG treatment caused increased apoptosis and elevated ROS‑induced stress in ARPE‑19 cells and these effects could be partly attenuated by MALAT1 knockdown. Increased gene expression levels of TNF‑α, MCP‑1, ICAM‑1 and VEGF induced by HG were also alleviated by MALAT1 inhibition. Therefore, lncRNA MALAT1 is the key factor in ARPE‑19 cell damage caused by HG and may be a promising therapeutic target for clinical DR therapy. However, further studies are still required to reveal the detailed mechanisms underlying lncRNA MALAT1 function.

Upregulation of TGF-β type II receptor in high glucose-induced vascular smooth muscle cells

BACKGROUND

Mortality in patients with diabetes mellitus is estimated above 65% due to cardiovascular diseases. The aim of study was to investigate the effects of high-glucose conditions on TGF-β type II receptor (TGFBR2) expression levels, cell viability, and migration rate in vascular smooth muscle cells (VSMCs).

METHODS

VSMCs were incubated in 30 mM and 50 mM of glucose for 24 h, 48 h, and 72 h periods. The gene and protein expression levels were investigated by Real-time qRT-PCR and western blotting techniques, respectively. The cell viability was evaluated by MTT assay. VSMC migration rate was also studied by wound healing assay.

RESULTS

The TGFBR2 gene and protein expression levels were significantly upregulated in all the groups treated with glucose in 24 h, 48 h, and 72 h periods. The cell viability was not significantly affected in values of 30 mM and 50 mM of glucose. The increase of migration rate of VSMCs was not significant.

CONCLUSION

The results suggested the increased expression levels of TGFBR2 in the response to high glucose conditions may modulate the cellular events through the signaling pathway network in VSMCs.