Crude Saponins of Panax notoginseng Have Neuroprotective Effects To Inhibit Palmitate-Triggered Endoplasmic Reticulum Stress-Associated Apoptosis and Loss of Postsynaptic Proteins in Staurosporine Differentiated RGC-5 Retinal Ganglion Cells

The Therapeutic Effect and Mechanism of Traditional Chinese Medicine in Type 2 Diabetes Mellitus and Its Complications

Traditional Chinese Medicine (TCM) has recently emerged as a beacon for the treatment of diabetes and its complications. Many TCMs that are commonly used, have the potentially demonstrated significant anti-diabetic effects. The mechanisms of these effects have been extensively discussed using modern techniques, such as genomics, mass spectrometry, and network pharmacology. Studies have demonstrated that TCM can influence glucose metabolism and pancreatic function via a diverse array of mechanisms including PI3K/AKT and AMPK pathways. TCM not only exhibits potential in the treatment of diabetes but also reduces the risk of diabetic complications. It is effective in the treatment of diabetic nephropathy (DN), diabetic retinopathy (DR), diabetic neuropathy (DPN), diabetic cardiomyopathy, and peripheral angiopathy. Research has demonstrated that prescriptions, Chinese herbal medicines, and their extracts play a role in a variety of molecular mechanisms such as antioxidation, apoptosis regulation, hypoxia improvement, autophagy, and promotion of glucose and lipid metabolism. The antioxidant properties of TCM have received considerable attention. Recent studies have demonstrated that they are capable of effectively eliminating free radicals from the body and reducing damage to cells caused by oxidative stress. Consequently, they are crucial in the treatment of diabetes and its associated complications. This review summarizes the ever-expanding scope of TCM applicability in the field of diabetes, providing crucial support and innovative ideas for modern healthcare. TCMs could help seek more effective pharmacological targets in basic study and as well serve as the complement to the strategy of diabetic prevention and treatment benefiting the patients. More and more large series of RCT and clinical investigations will eventually examine the efficacy of specific TCM formulas on the therapeutic effect of DM and its complication where currently treatments could not be satisfied.

Natural remedies proposed for the management of diabetic retinopathy (DR): diabetic complications

Diabetic retinopathy (DR) represents a significant and serious complication associated with diabetes mellitus (DM), often resulting in considerable visual impairment or even blindness. The intricate pathological processes underlying DR complicate the effectiveness of current treatment modalities. Studies have highlighted the potential of natural products in the treatment of DR via several beneficial effects including anti-inflammatory, antioxidant, anti-neovascular, and anti-apoptotic properties. Flavonoids, saponins, saccharides, and alkaloids exhibited various beneficial effects in DR in in vivo and in vitro studies. However, the clinical utilization of these natural compounds is hindered by issues such as inadequate specificity, low bioavailability, and potential toxicity. Therefore, there is a pressing need for rigorous clinical studies to confirm the efficacy of natural products in preventing or mitigating the progression of DR.

Underlying mechanisms of traditional Chinese medicine in the prevention and treatment of diabetic retinopathy: Evidences from molecular and clinical studies

As one of the most serious microvascular complications of diabetes mellitus (DM), diabetic retinopathy (DR) can cause visual impairment and even blindness. With the rapid increase in the prevalence of DM, the incidence of DR is also rising year by year. Preventing and effectively treating DR has become a major focus in the medical field. Traditional Chinese medicine (TCM) has a wealth of experience in treating DR and has achieved significant results with various herbs and TCM prescriptions. Traditional Chinese Medicine (TCM) provides a comprehensive therapeutic strategy for diabetic retinopathy (DR), encompassing anti-inflammatory and antioxidant actions, anti-neovascularization, neuroprotection, regulation of glucose metabolism, and inhibition of apoptosis. This review provides an overview of the current status of TCM treatment for DR in recent years, including experimental studies and clinical researches, to explore the clinical efficacy and the underlying modern mechanisms of herbs and TCM prescriptions. Besides, we also discussed the challenges TCM faces in treating DR, such as drug-drug interactions among TCM components and the lack of high-quality evidence-based medicine practice, which pose significant obstacles to TCM's application in DR.

Natural plant medications for the treatment of retinal diseases: The blood-retinal barrier as a clue

BACKGROUND

Retinal diseases significantly contribute to the global burden of visual impairment and blindness. The occurrence of retinal diseases is often accompanied by destruction of the blood‒retinal barrier, a vital physiological structure responsible for maintaining the stability of the retinal microenvironment. However, detailed summaries of the factors damage the blood‒retinal barrier and treatment methods involving natural plant medications are lacking.

PURPOSE

To comprehensively summarize and analyze the protective effects of active substances in natural plant medications on damage to the blood-retina barrier that occurs when retinal illnesses, particularly diabetic retinopathy, and examine their medicinal value and future development prospects.

METHODS

In this study, we searched for studies published in the ScienceDirect, PubMed, and Web of Science databases. The keywords used included natural plant medications, plants, natural herbs, blood retinal barrier, retinal diseases, diabetic retinopathy, age-related macular degeneration, and uveitis. Chinese herbal compound articles, non-English articles, warning journals, and duplicates were excluded from the analysis.

RESULTS

The blood‒retinal barrier is susceptible to high glucose, aging, immune responses, and other factors that destroy retinal homeostasis, resulting in pathological changes such as apoptosis and increased vascular permeability. Existing studies have shown that the active compounds or extracts of many natural plants have the effect of repairing blood-retinal barrier dysfunction. Notably, berberine, puerarin, and Lycium barbarum polysaccharides exhibited remarkable therapeutic effects. Additionally, curcumin, astragaloside IV, hesperidin, resveratrol, ginsenoside Rb1, luteolin, and Panax notoginseng saponins can effectively protect the blood‒retinal barrier by interfering with distinct pathways. The active ingredients found in natural plant medications primarily repair the blood‒retinal barrier by modulating pathological factors such as oxidative stress, inflammation, pyroptosis, and autophagy, thereby alleviating retinal diseases.

CONCLUSION

This review summarizes a series of plant extracts and plant active compounds that can treat retinal diseases by preventing and treating blood‒retinal barrier damage and provides reference for the research of new drugs for treating retinal diseases.

Pharmacokinetics and Oral Bioavailability of Panax Notoginseng Saponins Administered to Rats Using a Validated UPLC-MS/MS Method

Panax notoginseng saponins (PNS) are the most important bioactive components of P. Notoginseng. In this paper, an evaluation of the pharmacokinetics and oral absolute bioavailability of PNS was carried out following intravenous and oral administration of PNS to Sprague-Dawley rats. The plasma concentration of 28 PNS was determined using a validated UPLC-MS/MS system. The results demonstrated that Rb1(32.8%), Rg1(41.4%), R1(9.4%), Re(4.5%), and Rd(3.5%) are the five main ingredients of PNS for administration. After oral administration, it was found that the area under the curve (AUC_0-72 h) for these five major saponins was significantly different. AUC_0-72 h of Rb1 and Rd accounted for about 60% of all PNS exposure, while AUC_0-72 h of Rg1 and R1 only accounted for 0.7%, and Re was undetectable in plasma. Also, PPD, PPT, and CK were detected as the major PNS metabolites in vivo. Furthermore, it was shown that the total oral bioavailability of PNS was only 1.2%.

Potential therapeutic compounds from traditional Chinese medicine targeting endoplasmic reticulum stress to alleviate rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease which affects about 0.5-1% of people with symptoms that significantly impact a sufferer's lifestyle. The cells involved in propagating RA tend to display pro-inflammatory and cancer-like characteristics. Medical drug treatment is currently the main avenue of RA therapy. However, drug options are limited due to severe side effects, high costs, insufficient disease retardation in a majority of patients, and therapeutic effects possibly subsiding over time. Thus there is a need for new drug therapies. Endoplasmic reticulum (ER) stress, a condition due to accumulation of misfolded proteins in the ER, and subsequent cellular responses have been found to be involved in cancer and inflammatory pathologies, including RA. ER stress protein markers and their modulation have therefore been suggested as therapeutic targets, such as GRP78 and CHOP, among others. Some current RA therapeutic drugs have been found to have ER stress-modulating properties. Traditional Chinese Medicines (TCMs) frequently use natural products that affect multiple body and cellular targets, and several medicines and/or their isolated compounds have been found to also have ER stress-modulating capabilities, including TCMs used in RA treatment by Chinese Medicine practitioners. This review encourages, in light of the available information, the study of these RA-treating, ER stress-modulating TCMs as potential new pharmaceutical drugs for use in clinical RA therapy, along with providing a list of other ER stress-modulating TCMs utilized in treatment of cancers, inflammatory diseases and other diseases, that have potential use in RA treatment given similar ER stress-modulating capacity.

Inhibition of Autophagy Prevents Panax Notoginseng Saponins (PNS) Protection on Cardiac Myocytes Against Endoplasmic Reticulum (ER) Stress-Induced Mitochondrial Injury, Ca2+ Homeostasis and Associated Apoptosis

Endoplasmic reticulum (ER) stress is often closely linked to autophagy, hypoxia signaling, mitochondrial biogenesis and reactive oxygen species (ROS) responses. Understanding the interaction between ER stress, mitochondrial function and autophagy is of great importance to provide new mechanisms for the pathology, prevention and treatment of cardiovascular diseases. Our previous study has reported that Panax notoginseng saponins (PNS) protection against thapsigargin (TG)-induced ER stress response and associated cell apoptosis in cardiac myocytes is calcium dependent and mediated by ER Ca²⁺ release through RyR₂. However, whether its protection upon ER stress and associated apoptosis is related to mitochondrial function and autophagy remains largely unknown. Here, we investigated the roles of PNS played in TG-induced mitochondrial function, ROS accumulation and autophagy. We also assessed its effects on Ca²⁺ homeostasis, ER stress response and associated cell death in the presence of autophagy inhibition. PNS-pretreated primary cultured neonatal rat cardiomyocytes were stimulated with TG to induce ER stress response. Mitochondrial potential (Δψm) was measured by JC-1. The general and mitochondrial ROS were measured by DCFH-DA and MitoSOX Red, respectively. Autophagy was evaluated by immunofluorescence of LC3, and immunoblots of LC3, p62, ATG7 and PINK1. In addition, mRFP-GFP-LC3 labeling was used to assess the autophagic influx. SiATG7 transfected H9c2 cells were generated to inhibit autophagy. Cytosolic and ER Ca²⁺ dynamics were investigated by calcium imaging. RyR₂ oxidation was tested by oxyblot. Cell viability was examined by TUNEL assay. ER stress response and cell apoptosis were detected by immunoblots of BiP, CHOP, Cleaved Caspase-3 and Caspase-12. The results demonstrated that firstly, PNS protects against TG-induced mitochondrial injury and ROS accumulation. Secondly, PNS enhances autophagy in TG-induced cardiac myocytes. Thirdly, inhibition of autophagy diminishes PNS prevention of TG-induced mitochondrial injury, ROS accumulation and disruption of Ca²⁺ homeostasis. Last but not least, inhibition of autophagy abolishes PNS protection against TG-induced ER stress response and associated apoptosis. In summary, PNS protection against ER stress response and associated apoptosis is related to the regulation of mitochondrial injury and ROS overproduction via modulation of autophagy. These data provide new insights for molecular mechanisms of PNS as a potential preventive approach to the management of cardiovascular diseases.

Pien Tze Huang (PZH) as a Multifunction Medicinal Agent in Traditional Chinese Medicine (TCM): a review on cellular, molecular and physiological mechanisms

RELEVANCE

Pien Tze Huang (PZH) is a well-known Traditional Chinese Medicine (TCM), characterized by a multitude of pharmacological effects, such as hepatoprotection and inhibition of inflammation and cell proliferative conditions. Many of these effects have been validated at the cellular, molecular and physiological levels but, to date, most of these findings have not been comprehensively disclosed.

OBJECTIVES

This review aims to provide a critical summary of recent studies focusing on PZH and its multiple pharmacological effects. As a result, we further discuss some novel perspectives related to PZH's mechanisms of action and a holistic view of its therapeutic activities.

METHODS

A systematic review was performed focusing on PZH studies originated from original scientific resources. The scientific literature retrieved for this work was obtained from International repositories including NCBI/PubMed, Web of Science, Science Direct and China National Knowledge Infrastructure (CNKI) databases.

RESULTS

The major active componentes and their potential functions, including hepatoprotective and neuroprotective effects, as well as anti-cancer and anti-inflammatory activities, were summarized and categorized accordingly. As indicated, most of the pharmacological effects were validated in vitro and in vivo. The identification of complex bioactive components in PZH may provide the basis for further therapeutic initiatives.

CONCLUSION

Here we have collectively discussed the recent evidences covering most, if not all, pharmacological effects driven by PZH. This review provides novel perspectives on understanding the modes of action and the holistic view of TCM. The rational development of future clinical trials will certainly provide evidence-based medical evidences that will also confirm the therapeutic advantages of PZH, based on the current information available.

Targeted pharmacotherapy against neurodegeneration and neuroinflammation in early diabetic retinopathy

Diabetic retinopathy (DR), the most frequent complication of diabetes, is one of the leading causes of irreversible blindness in working-age adults and has traditionally been regarded as a microvascular disease. However, increasing evidence has revealed that synaptic neurodegeneration of retinal ganglion cells (RGCs) and activation of glial cells may represent some of the earliest events in the pathogenesis of DR. Upon diabetes-induced metabolic stress, abnormal glycogen synthase kinase-3β (GSK-3β) activation drives tau hyperphosphorylation and β-catenin downregulation, leading to mitochondrial impairment and synaptic neurodegeneration prior to RGC apoptosis. Moreover, glial cell activation triggers enhanced inflammation and oxidative stress, which may accelerate the deterioration of diabetic RGCs neurodegeneration. These findings have opened up opportunities for therapies, such as inhibition of GSK-3β, glial cell activation, glutamate excitotoxicity and the use of neuroprotective drugs targeting early neurodegenerative processes in the retina and halting the progression of DR before the manifestation of microvascular abnormalities. Such interventions could potentially remedy early neurodegeneration and help prevent vision loss in people suffering from DR.

Mechanisms behind Retinal Ganglion Cell Loss in Diabetes and Therapeutic Approach

Diabetes produces several changes in the body triggered by high glycemia. Some of these changes include altered metabolism, structural changes in blood vessels and chronic inflammation. The eye and particularly the retinal ganglion cells (RGCs) are not spared, and the changes eventually lead to cell loss and visual function impairment. Understanding the mechanisms resulting in RGC damage and loss from diabetic retinopathy is essential to find an effective treatment. This review focuses mainly on the signaling pathways and molecules involved in RGC loss and the potential therapeutic approaches for the prevention of this cell death. Throughout the manuscript it became evident that multiple factors of different kind are responsible for RGC damage. This shows that new therapeutic agents targeting several factors at the same time are needed. Alpha-1 antitrypsin as an anti-inflammatory agent may become a suitable option for the treatment of RGC loss because of its beneficial interaction with several signaling pathways involved in RGC injury and inflammation. In conclusion, alpha-1 antitrypsin may become a potential therapeutic agent for the treatment of RGC loss and processes behind diabetic retinopathy.

Network Pharmacology-based Investigation of the Underlying Mechanism of Panax notoginseng Treatment of Diabetic Retinopathy

Background: Panax notoginseng, a Chinese herbal medicine, has been widely used to treat vascular diseases. Diabetic retinopathy (DR) is one of the complications of diabetic microangiopathy. According to recent studies, the application of Panax notoginseng extract and related Chinese patent medicine preparations can significantly improve DR. However, the pharmacological mechanisms remain unclear. Therefore, the purpose of this study was to decipher the potential mechanism of Panax notoginseng treatment of DR using network pharmacology.

Method: We evaluated and screened the active compounds of Panax notoginseng using the Traditional Chinese Medicine Systems Pharmacology database and collected potential targets of the compounds by target fishing. A multi-source database was also used to organize targets of DR. The potential targets as the treatment of DR with Panax notoginseng were then obtained by matching the compound targets with the DR targets. Using protein-protein interaction networks and topological analysis, interactions between potential targets were identified. In addition, we also performed gene ontology-biological process and pathway enrichment analysis for the potential targets by using the Biological Information Annotation Database.

Results: Eight active ingredients of Panax notoginseng and 31 potential targets for the treatment of DR were identified. The screening and enrichment analysis revealed that the treatment of DR using Panax notoginseng primarily involved 28 biological processes and 10 related pathways. Further analyses indicated that angiogenesis, inflammatory reactions, and apoptosis may be the main processes involved in the treatment of DR with Panax notoginseng. In addition, we determined that the mechanism of intervention of Panax notoginseng in treating DR may involve five core targets, VEGFA, MMP-9, MMP-2, FGF2, and COX-2.

Conclusion: Panax notoginseng may treat diabetic retinopathy through the mechanism of network pharmacological analysis. The underlying molecular mechanisms were closely related to the intervention of angiogenesis, inflammation, and apoptosis with VEGFA, MMP-9, MMP-2, FGF2, and COX-2 being possible targets.

Ginseng for an eye: effects of ginseng on ocular diseases

The sense of vision is the primary means by which we gather information from our surroundings, and vision loss, therefore, severely compromises the life of the affected individuals, their families, and society. Loss of vision becomes more frequent with age, and diabetic retinopathy, age-related macular degeneration, cataracts, and glaucoma are the major causes of vision impairment. To find active pharmacological compounds that might prevent or ameliorate the vision-threatening eye diseases, numerous studies have been performed, and some botanical compounds, including those extracted from ginseng, have been shown to possess beneficial effects in the treatment or prevention of common ocular diseases. In this review, we summarize the recent reports investigating the therapeutic effects of ginseng and ginsenosides on diverse ocular diseases and discuss their therapeutic potential.

Tetrahydroxystilbene Glucoside Ameliorates Infrasound-Induced Central Nervous System (CNS) Injury by Improving Antioxidant and Anti-Inflammatory Capacity

Background

Infrasound is a major threat to global health by causing injuries of the central nervous system (CNS). However, there remains no effective therapeutic agent for preventing infrasound-caused CNS injury. 2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-glycoside (THSG) exerts protective function against CNS injuries and may have beneficial effects on infrasound-induced CNS impairment.

Methods

A mouse model with CNS (oxidative stress-induced inflammation and neuronal apoptosis) injuries was established when the mouse was exposed to the infrasound of 16 Hz at 130 dB for 2 h each day and the duration of treatment was 8 d. The mice were divided into the control (CG, healthy mice), the model (MG, model mice), and the THSG (EG, experimental group, model mice treated with THSG) groups. The learning and memory impairments caused by infrasound were examined using a Morris water maze test. Lipid profiles, antioxidant biomarkers, and inflammatory cytokines in hippocampus tissue were measured by using corresponding ELISA kits. Meanwhile, BCL-2/BAX/caspase-3 signaling pathway was measured in the hippocampi and prefrontal cortex of the mouse brain using real-time qPCR and Western blot. Nissl's stain was used to measure neuronal necrosis in the hippocampi and prefrontal cortex of the mouse brain.

Results

THSG significantly ameliorated the learning and memory impairments caused by infrasound. On the other hand, THSG improved lipid profiles, increased antioxidant properties by affecting the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA), and displayed anti-inflammatory action via the downregulation of IL- (interleukin-) 6, IL-8, IL-10, TNF- (tumor necrosis factor-) α, and hs-CRP (high-sensitivity C-reactive protein) in the hippocampal tissues of the mouse model (P < 0.05). Additionally, Nissl's stain showed that THSG inhibited infrasound-induced neuronal necrosis in the hippocampi and prefrontal cortex. Besides, THSG exerted antiapoptosis function by upregulating the level of Bcl-2 and downregulating the levels of BAX and caspase-3 in the hippocampi.

Conclusion

THSG may be an effective anti-infrasound drug against CNS injury by improving antioxidant, anti-inflammatory, antiapoptosis, and antinecrosis capacities. Further research is still needed to confirm the exact molecular mechanism.

Neuroprotective Effects of Ginsenoside Rg1 against Hyperphosphorylated Tau-Induced Diabetic Retinal Neurodegeneration via Activation of IRS-1/Akt/GSK3β Signaling

We have recently demonstrated that tau hyperphosphorylation causes diabetic synaptic neurodegeneration of retinal ganglion cells (RGCs), which might be the earliest affair during the pathogenesis of diabetic retinopathy (DR). Thus, there is a pressing need to seek therapeutic agents possessing neuroprotective effects against tau hyperphosphorylation in RGCs for arresting the progression of DR. Here, using a well-characterized diabetes model of db/db mouse, we discovered that topical ocular application of 10 mg/kg/day of ginsenoside Rg1 (GRg1), one of the major active ingredients extracted from Panax ginseng and Panax notoginseng, ameliorated hyperphosphorylated tau-triggered RGCs synaptic neurodegeneration in diabetic mice. The neuroprotective effects of GRg1 on diabetic retinae were abrogated when retinal IRS-1 or Akt was suppressed by intravitreal injection with si-IRS-1 or topically coadministered with a specific inhibitor of Akt, respectively. However, selective repression of retinal GSK3β by intravitreal administration of si-GSK3β rescued the neuroprotective properties of GRg1 when Akt was inactivated. Therefore, the present study showed for the first time that GRg1 can prevent hyperphosphorylated tau-induced synaptic neurodegeneration of RGCs via activation of IRS-1/Akt/GSK3β signaling in the early phase of DR. Moreover, our data clarify the potential therapeutic significance of GRg1 for neuroprotective intervention strategies of DR.

Reactive Oxygen Species-Mediated Damage of Retinal Neurons: Drug Development Targets for Therapies of Chronic Neurodegeneration of the Retina

The significance of oxidative stress in the development of chronic neurodegenerative diseases of the retina has become increasingly apparent in recent years. Reactive oxygen species (ROS) are free radicals produced at low levels as a result of normal cellular metabolism that are ultimately metabolized and detoxified by endogenous and exogenous mechanisms. In the presence of oxidative cellular stress, ROS are produced in excess, resulting in cellular injury and death and ultimately leading to tissue and organ dysfunction. Recent studies have investigated the role of excess ROS in the pathogenesis and development of chronic neurodegenerative diseases of the retina including glaucoma, diabetic retinopathy, and age-related macular degeneration. Findings from these studies are promising insofar as they provide clear rationales for innovative treatment and prevention strategies of these prevalent and disabling diseases where currently therapeutic options are limited. Here, we briefly outline recent developments that have contributed to our understanding of the role of ROS in the pathogenesis of chronic neurodegenerative diseases of the retina. We then examine and analyze the peer-reviewed evidence in support of ROS as targets for therapy development in the area of chronic neurodegeneration of the retina.

Evaluating the protective mechanism of panax notoginseng saponins against oxidative stress damage by quantifying the biomechanical properties of single cell

Panax notoginseng saponins (PNS) have shown to be the biologically active constituents responsible for the therapeutic action of panax notoginseng. PNS could help to restrain the oxidative stress, however, whether biomechanical properties of the single cell involve in the protective effect exerted by PNS against oxidative stress injury remains unclear. In this work, we investigated the protective mechanism of PNS against oxidative stress based on the PeakForce Tapping technology firstly, focusing on the biomechanical properties of single human umbilical vascular endothelium cell (HUVEC). PNS display distinct inhibition on the reduction of the young's modulus of cells caused by oxidative stress damage. Combining with immunofluorescence assay, it indicates that improving the stability of cytoskeleton is a significant way for PNS to play a protective role in HUVEC cells during oxidative damage. This work provides a new idea for exploring the functional mechanism of traditional Chinese medicine at the single cell level, and reveals great potential of the atomic force microscope in studying the drug mechanism.

Progress in Experimental and Clinical Research of the Diabetic Retinopathy Treatment Using Traditional Chinese Medicine

Diabetic retinopathy (DR), one of the most common microvascular complications of diabetic mellitus, is currently the main cause of adult-acquired blindness. The pathogenesis of DR is complex and the current clinical application of various treatment methods cannot completely prevent the development of this disease. Many reports have been published regarding the treatment of DR with Traditional Chinese Medicine (TCM), which has received increasing attention from medical practitioners worldwide. Studies published between 1994 and April 2017 were collected from the CNKI, VIP, Medline and Web of Science databases, as well as from Chinese traditional books and Chinese Pharmacopoeia, subsequently obtaining more than 550 studies. Thereafter, the status quo of DR treatment using TCM had been summarized according to four aspects - compound formula therapy, Chinese herbal medicine extracts and monomer therapy, integrated traditional Chinese and Western medicine therapy, and Chinese medicine external treatment. According to the literature reviewed herein, TCM has had definite effects on the prevention and treatment of DR, especially when used in combination with modern medical methods. However, the lack of a unified standard on the syndrome differentiation of DR and the lack of support of evidence-based medicine theory in clinical practice have been consistent concerns in previous research studies and needs to be addressed in subsequent studies.

Neuroprotective effect of He-Ying-Qing-Re formula on retinal ganglion cell in diabetic retinopathy

ETHNOPHARMACOLOGY RELEVANCE

He-Ying-Qing-Re Formula (HF) was empirically modified from Si-Miao-Yong-An Decoction (SD), which was recorded in the literature of Divine Doctor's Secret Transmission, and has been utilized for centuries to treat vasculopathy through clearing heat and accelerating bloodstream. HF has been used as an effective holistic treatment of diabetic retinopathy (DR) for decades and experimentally reported to ameliorate retinal condition in diabetic mice.

AIM OF THE STUDY

Our study aims to investigate the effect of HF in preventing sustained hyperglycemia and hyperlipidemia-associated retinal ganglion cell (RGC) cell death and its possible mechanism.

MATERIALS AND METHODS

Chromatographic fingerprint of HF was obtained upon the UPLC-based analytic system; Diabetic retinopathy was established in streptozotocin (STZ) injection-induced hyperglycemic mice; Alterations of retinal structure was assayed by H&E staining. Expression of PSD-95 and CHOP in retinae was assessed by immunofluorescence; RGC cell line (mRGC) was used for in vitro study. Cell death was analyzed by flow cytometry; Intracellular reactive oxygen species (ROS) was measured by 2',7'-dichlorofluorescin diacetate (DCFDA); Apoptosis-related proteins and signaling were monitored with immunoblotting and colorimetric assay.

RESULTS

Chlorogenic acid, ferulic acid, and rutin were identified in HF. HF attenuates the loss of RGCs, thinning of inner retinal layers in diabetic mice. Furthermore, expressions of Brn3a and PSD-95 were restored while CHOP level was downregulated upon HF treatment. In vitro study, HF alleviates H2O2-induced apoptosis of mRGCs and loss of postsynaptic protein via scavenging ROS and suppressing ATF4/CHOP-mediated endoplasmic reticulum stress and mitochondria-related pro-apoptotic factors, probably as cleaved-caspase-3, and phospho-p38 mitogen-activated protein kinase (MARK). Meanwhile, both pro-survival protein levels like Bcl-2/Bcl-xL and postsynaptic protein of PSD-95 were upregulated upon HF treatment.

CONCLUSION

HF administration was a valid therapeutic approach for DR treatment, oriented at the blockade of endoplasmic reticulum- and mitochondria-dependent oxidative stress-induced retinal neurodegeneration including RGC apoptosis.

Notoginsenoside R7 suppresses cervical cancer via PI3K/PTEN/Akt/mTOR signaling

Notoginsenoside R7 was isolated from Panax notoginseng, a plant used commonly in traditional Chinese medicine. We investigated the anti-cancer effects of R7 in HeLa cells in vitro and in vivo, and explored the underlying mechanisms of action. R7 dose-dependently inhibited HeLa cell proliferation and induced apoptosis in vitro, In silico docking-based screening assays showed that R7 can directly bind Akt. Pretreatment with the Akt inhibitor LY294002 synergistically enhanced the R7 anti-proliferation and anti-apoptosis effects in HeLa cells, confirming that R7 acts through the PI3K/Akt pathway. Consistent with the in vitro findings, R7 exerted anti-tumor effects in a mouse xenograft model by targeting PI3K (PTEN) and Akt, activating the pro-apoptotic Bcl-2 family and, subsequently, caspase family members. R7 treatment activated PTEN and downregulated mTOR phosphorylation without affecting mTOR expression, though regulatory-associated protein of mTOR (raptor) expression declined. Our study suggests that R7 is a promising chemotherapeutic agent for the treatment of cervical cancer and other PI3K/PTEN/Akt/mTOR signaling-associated tumors.

Inhibition of Starvation-Triggered Endoplasmic Reticulum Stress, Autophagy, and Apoptosis in ARPE-19 Cells by Taurine through Modulating the Expression of Calpain-1 and Calpain-2

Age-related macular degeneration (AMD) is a complex disease with multiple initiators and pathways that converge on death for retinal pigment epithelial (RPE) cells. In this study, effects of taurine on calpains, autophagy, endoplasmic reticulum (ER) stress, and apoptosis in ARPE-19 cells (a human RPE cell line) were investigated. We first confirmed that autophagy, ER stress and apoptosis in ARPE-19 cells were induced by Earle’s balanced salt solution (EBSS) through starvation to induce RPE metabolic stress. Secondly, inhibition of ER stress by 4-phenyl butyric acid (4-PBA) alleviated autophagy and apoptosis, and suppression of autophagy by 3-methyl adenine (3-MA) reduced the cell apoptosis, but the ER stress was minimally affected. Thirdly, the apoptosis, ER stress and autophagy were inhibited by gene silencing of calpain-2 and overexpression of calpain-1, respectively. Finally, taurine suppressed both the changes of the important upstream regulators (calpain-1 and calpain-2) and the activation of ER stress, autophagy and apoptosis, and taurine had protective effects on the survival of ARPE-19 cells. Collectively, this data indicate that taurine inhibits starvation-triggered endoplasmic reticulum stress, autophagy, and apoptosis in ARPE-19 cells by modulating the expression of calpain-1 and calpain-2.

Nogo receptor knockdown and ciliary neurotrophic factor attenuate diabetic retinopathy in streptozotocin-induced diabetic rats

Diabetic retinopathy (DR) is a common complication of diabetes mellitus (DM). We investigated whether Nogo receptor (NgR) knockdown and ciliary neurotrophic factor (CNTF) treatment, either alone or in combination, ameliorated diabetic retinopathy (DR) in diabetic rat model. STZ‑induced diabetic rats were administrated for a total of 12 weeks with 3 µM siRNA (5 µl) once every 6 weeks and/or 1 µg CNTF weekly. The retinal tissues were excised. We measured cell number in ganglion cell layer (GCL) using H&E staining and cell apoptosis using TUNEL assay. Bax, Bcl‑2, Caspase‑3, F‑actin, GAP‑43, NgR, RhoA and Rock1 levels were then analyzed by Western blotting, Immunohistochemistry or Real‑time PCR. We found that NgR siRNA or CNTF injection alone significantly increased cell count in GCL in diabetic rats, inhibited ganglion cell apoptosis, elevated Bcl‑2, F‑actin and GAP‑43, and decreased Bax, Caspase‑3, NgR, RhoA and Rock1 levels. Combination treatment further prevented retinal ganglion cell loss, enhanced growth cone cytoskeleton and axonal regeneration, and suppressed NgR/RhoA/Rock1. Our results indicate that combination therapy has therapeutic potential for the treatment of DR.

Recent Update on the Role of Chinese Material Medica and Formulations in Diabetic Retinopathy

Diabetes mellitus is one of the most frequent endocrine disorders, affecting populations worldwide. Diabetic retinopathy (DR) is the most frequent microvascular complication of diabetes in patients aged 20 and over. Major complications of DR include intraocular neovascularization, inter-retinal edema, hemorrhage, exudates and microaneurysms. Therefore, timely medical attention and prevention are required. At present, laser-assisted therapy and other operational procedures are the most common treatment for DR. However, these treatments can cause retinal damage and scarring. Also, use of the majority of traditional medicines is not supported by clinical evidence. However, due to accumulating scientific evidence, traditional natural medications may assist in delaying or preventing the progression of DR. This review focuses on evidence for the role of traditional natural medicines and their mechanisms of action and pharmacological test results in relation to the progression of DR.

Nerve growth factor protects against palmitic acid-induced injury in retinal ganglion cells

Accumulating evidence supports an important role for nerve growth factor (NGF) in diabetic retinopathy. We hypothesized that NGF has a protective effect on rat retinal ganglion RGC-5 cells injured by palmitic acid (PA), a metabolic factor implicated in the development of diabetes and its complications. Our results show that PA exposure caused apoptosis of RGC-5 cells, while NGF protected against PA insult in a concentration-dependent manner. Additionally, NGF significantly attenuated the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) in RGC-5 cells. Pathway inhibitor tests showed that the protective effect of NGF was completely reversed by LY294002 (PI3K inhibitor), Akt VIII inhibitor, and PD98059 (ERK1/2 inhibitor). Western blot analysis revealed that NGF induced the phosphorylation of Akt/FoxO1 and ERK1/2 and reversed the PA-evoked reduction in the levels of these proteins. These results indicate that NGF protects RGC-5 cells against PA-induced injury through anti-oxidation and inhibition of apoptosis by modulation of the PI3K/Akt and ERK1/2 signaling pathways.