Tetramethylpyrazine Protects Retinal Capillary Endothelial Cells (TR-iBRB2) against IL-1β-Induced Nitrative/Oxidative Stress

Polystyrene Sulfonate Resin as an Ophthalmic Carrier for Enhanced Bioavailability of Ligustrazine Phosphate Controlled Release System

Topical ocular sustained-release drug delivery systems represent an effective strategy for the treatment of ocular diseases, for which a suitable carrier has yet to be sufficiently developed. Herein, an eye-compatible sodium polystyrene sulfonate resin (SPSR) was synthesized with a uniform particle size of about 3 μm. Ligustrazine phosphate (LP) was adsorbed to SPSR by cation exchange to form LP@SPSR. LP@SPSR suspension eye drops were further developed using the combination of Carbopol 934P and xanthan gum as suspending agents. The LP@SPSR suspension showed a sustained release in vitro, which was consistent with the observed porcine corneal penetration ex vivo. Pharmacokinetics in tear fluid of rabits indicated that LP@SPSR suspension led to prolonged ocular retention of LP and a 2-fold improved the area under the drug concentration-time curve (AUC0-t). Pharmacokinetics in the aqueous humor of rabbits showed 2.8-fold enhancement in the AUC0-t compared to LP solution. The LP@SPSR suspension exhibited no cytotoxicity to human corneal epithelial cells, nor irritation was observed in rabbit eyes. Thus, the LP@SPSR suspension has been validated as a safe and sustained release system leading to enhanced ophthalmic bioavailability for treating ocular diseases.

Uncovering the Therapeutic Potential of Phosphocreatine in Diabetic Retinopathy: Mitigating Mitochondrial Dysfunction and Apoptosis via JAK2/STAT3 Signaling Pathway

Diabetic retinopathy (DR) stands as a prevalent complication of diabetes mellitus, causing damage to the delicate retinal capillaries and potentially leading to visual impairment. While the exact underlying cause of DR remains elusive, compelling research suggests that mitochondrial energy deficiency and the excessive generation of reactive oxygen species (ROS) play pivotal roles in its pathogenesis. Recognizing that controlling hyperglycemia alone fails to reverse the defects in retinal mitochondria induced by diabetes, current strategies seek to restore mitochondrial function as a means of safeguarding against DR. To address this pressing issue, a comprehensive study was undertaken to explore the potential of phosphocreatine (PCr) in bolstering mitochondrial bioenergetics and providing protection against DR via modulation of the JAK2/STAT3 signaling pathway. Employing rat mitochondria and RGC-5 cells, the investigation meticulously assessed the impact of PCr on ROS production, mitochondrial membrane potential, as well as the expression of crucial apoptotic and JAK2/STAT3 signaling pathway proteins, utilizing cutting-edge techniques such as high-resolution respirometry and western blotting. The remarkable outcomes revealed that PCr exerts a profound protective influence against DR by enhancing mitochondrial function and alleviating diabetes-associated symptoms and biochemical markers. Notably, PCr administration resulted in an upregulation of antiapoptotic proteins, concomitant with a downregulation of proapoptotic proteins and the JAK2/STAT3 signaling pathway. These significant findings firmly establish PCr as a potential therapeutic avenue for combating diabetic retinopathy. By augmenting mitochondrial function and exerting antiapoptotic effects via the JAK2/STAT3 signaling pathway, PCr demonstrates promising efficacy both in vivo and in vitro, particularly in counteracting the oxidative stress engendered by hyperglycemia. In summary, our study sheds light on the potential of PCr as an innovative therapeutic strategy for diabetic retinopathy. By bolstering mitochondrial function and exerting protective effects via the modulation of the JAK2/STAT3 signaling pathway, PCr holds immense promise in ameliorating the impact of DR in the face of oxidative stress induced by hyperglycemia.

Tetramethylpyrazine contributes to the neuroprotection in a rodent epileptic model of pentylenetetrazole-induced kindling

OBJECTIVES

In this study, tetramethylpyrazine (TMP) was evaluated for its therapeutic potential as an alternative therapy for epileptogenesis and its associated comorbidities in rats.

METHODS

The sub-convulsant dose of pentylenetetrazole (PTZ) (35 mg/kg, intraperitoneally) was injected on alternative days to produce kindling for 32 days and observed for seizure score percent of kindled animals in each group. After kindling, the animals were evaluated in models of anxiety, memory and predictive of depression. The neuroprotective effect of TMP was assessed by estimating the biochemical parameters in the cortex and hippocampus of the brain. Histopathological alterations were also observed in the cortex and hippocampus (CA1, CA3 and DG).

KEY FINDINGS

The administration of TMP reduced the seizure score and percentage of kindled animals dose-dependently. Furthermore, TMP significantly improved the behavioural parameters measured in the predictive models of depression but not in the anxiety and cognitive performances of the animals. The oxidative-nitrosative stress, excitotoxicity, neuroinflammation and histological alterations in the brain induced by PTZ were significantly mitigated by administering the TMP high dose of 60 mg/kg.

CONCLUSION

In conclusion, the TMP attenuated the depression behaviour in the PTZ-induced kindled rats, and reduced the oxidative-nitrosative stress, excitotoxicity, neuroinflammation and histological alterations of the brain.

Comparative efficacy of five most common traditional Chinese medicine monomers for promoting recovery of motor function in rats with blunt spinal cord injury: a network meta-analysis

Objective

This research employed a network meta-analysis (NMA) to examine the effectiveness of five traditional Chinese medicine (TCM) monomers for promoting motor function recovery in rats with blunt spinal cord injury (SCI).

Methods

Wangfang, China National Knowledge Infrastructure, Web of Science, Embase, Chinese Scientific Journal Database, PubMed, and the Chinese Biomedical Literature Databases were searched for retrieving relevant articles published from their inception to December 2022. Two reviewers performed screening of search results, data extraction, and literature quality assessment independently.

Results

For this meta-analysis, 59 publications were included. Based on the recovery of motor function at weeks 1, 2, 3, and 4 in NMA, almost all TCM groups had significantly increased positive effects than the negative control animals. In terms of cumulative probability, the tanshinone IIA (TIIA) group ranked first in restoring motor function in the first week after blunt SCI, and the resveratrol (RSV) group ranked first during the last 3 weeks.

Conclusion

The NMA revealed that TCM monomers could effectively restore motor function in the rat model of blunt SCI. In rats with blunt SCI, TIIA may be the most effective TCM monomer during the first week, whereas RSV may be the most effective TCM monomer during the last 3 weeks in promoting motor function recovery. For better evidence reliability in preclinical investigations and safer extrapolation of those findings into clinical settings, further research standardizing the implementation and reporting of animal experiments is required.

Systematic Review Registration

https://inplasy.com/, identifier INPLASY202310070.

Network pharmacology mechanism of Scutellarin to inhibit RGC pyroptosis in diabetic retinopathy

To investigate the effect of scutellarin (SCU) in diabetic retinopathy (DR) and explore the associated molecular network mechanism. The animal model of DR was established from diabetic mellitus (DM) rats by intraperitoneally injected streptozotocin (STZ) at dosage 55 mg/kg. Meanwhile, SCU was intraperitoneally administrated to protect retina from cell pyroptosis induced by DM, and cell pyroptosis was detected by using HE, Nissl staining, and immunofluorescence recognition. Moreover, the hub gene involving in pyroptosis in DR was screened by bioinformatics and network pharmacology, designated as Venny intersection screen, GO and KEGG analysis, PPI protein interaction, and molecular docking. Lastly, the expressional change of hub genes were validated with experimental detection. Cell pyroptosis of the DR, specifically in retina ganglion cells (RGC), was induced in DM rats; SCU administration results in significant inhibition in the cell pyroptosis in DR. Mechanically, 4084 genes related to DR were screened from GeneCards and OMIM databases, and 120 SCU therapeutic targets were obtained, by using GeneCards, TCMSP with Swiss Target Prediction databases. Moreover, 357 targets related to pyroptosis were found using GenenCards database, and Drug, disease and phenotypic targets were analyzed online using the Draw Venn Diagram website, and 12 cross targets were obtained. Through GO function and KEGG pathway enrichment analysis, 659 BP related items, 7 CC related items, 30 MF related items, and 70 signal pathways were screened out; Of these, eleven proteins screened from cross-target PPI network were subsequently docked with the SCU, and their expressions including caspase-1, IL-1β, IL-18, GSDMD and NLRP3 in RGC indicated by immunofluorescence, and the mRNA expression for caspase-1 in DR indicated by quantitative PCR, were successfully validated. SCU can effectively protect RGC pyroptosis in DR, and underlying mechanisms are involved in the inhibition of caspase-1, GSDMD, NLRP3, IL-1β and IL-18. Our findings therefore provide crucial evidence to support the clinic practice of SCU for the treatment of DR, and explained the underlying molecular network mechanism.

Ginkgo biloba extracts protect human retinal Müller glial cells from t-BHP induced oxidative damage by activating the AMPK-Nrf2-NQO-1 axis

OBJECTIVES

Retinal Müller glial cell loss is almost involved in all retinal diseases, especially diabetic retinopathy (DR). Oxidative stress significantly contributes to the development of Müller glial cell loss. Ginkgo biloba extracts (GBE) have been reported to possess antioxidant property, beneficial in treating human retinal diseases. However, little is known about its role in Müller glial cells. This study investigated the protective effect of GBE (prepared from ginkgo biloba dropping pills) in human Müller glial cells against tert-butyl hydroperoxide (t-BHP)-induced oxidative stress and its underlying molecular mechanism.

METHODS

MIO-M1 cells were pretreated with or without GBE prior to the exposure to t-BHP-induced oxidative stress. Cell viability, cell death profile and lipid peroxidation were subsequently assessed. Protein expression of the key anti-oxidative signalling factors were investigated.

KEY FINDINGS

We showed that GBE can effectively protect human MIO-M1 cells from t-BHP-induced oxidative injury by improving cell viability, reducing intracellular ROS accumulation and suppressing lipid peroxidation, which effect is likely mediated through activating AMPK-Nrf2-NQO-1 antioxidant respondent axis.

CONCLUSIONS

Our study is the first to reveal the great potentials of GBE in protecting human retinal Müller glial cell loss against oxidative stress. GBE might be used to prevent human retinal diseases particularly DR.

IL-33 via PKCμ/PRKD1 Mediated α-Catenin Phosphorylation Regulates Endothelial Cell-Barrier Integrity and Ischemia-Induced Vascular Leakage

Angiogenesis, neovascularization, and vascular remodeling are highly dynamic processes, where endothelial cell-cell adhesion within the vessel wall controls a range of physiological processes, such as growth, integrity, and barrier function. The cadherin-catenin adhesion complex is a key contributor to inner blood-retinal barrier (iBRB) integrity and dynamic cell movements. However, the pre-eminent role of cadherins and their associated catenins in iBRB structure and function is not fully understood. Using a murine model of oxygen-induced retinopathy (OIR) and human retinal microvascular endothelial cells (HRMVECs), we try to understand the significance of IL-33 on retinal endothelial barrier disruption, leading to abnormal angiogenesis and enhanced vascular permeability. Using electric cell-substrate impedance sensing (ECIS) analysis and FITC-dextran permeability assay, we observed that IL-33 at a 20 ng/mL concentration induced endothelial-barrier disruption in HRMVECs. The adherens junction (AJs) proteins play a prominent role in the selective diffusion of molecules from the blood to the retina and in maintaining retinal homeostasis. Therefore, we looked for the involvement of adherens junction proteins in IL-33-mediated endothelial dysfunction. We observed that IL-33 induces α-catenin phosphorylation at serine/threonine (Ser/Thr) residues in HRMVECs. Furthermore, mass-spectroscopy (MS) analysis revealed that IL-33 induces the phosphorylation of α-catenin at Thr654 residue in HRMVECs. We also observed that PKCμ/PRKD1-p38 MAPK signaling regulates IL-33-induced α-catenin phosphorylation and retinal endothelial cell-barrier integrity. Our OIR studies revealed that genetic deletion of IL-33 resulted in reduced vascular leakage in the hypoxic retina. We also observed that the genetic deletion of IL-33 reduced OIR-induced PKCμ/PRKD1-p38 MAPK-α-catenin signaling in the hypoxic retina. Therefore, we conclude that IL-33-induced PKCμ/PRKD1-p38 MAPK-α-catenin signaling plays a significant role in endothelial permeability and iBRB integrity.

Traditional Chinese Medicine Injections for Diabetic Retinopathy: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

Background: The aim of this study was to compare the efficacy of different injected Traditional Chinese Medicines in the treatment of diabetic retinopathy (DR) and to provide a reference for the selection of adjuvant therapy for DR. Content: Related literature in multiple biological databases and websites was searched up to April 15, 2022, without language and publication time restrictions. A Bayesian network meta-analysis was used to analyze the included studies. Summary: Compared with conventional treatment, the combined use of injected Traditional Chinese Medicines, including astragalus, danhong, Ginkgo biloba extract powder, ginkgo leaf extract and dipyridamole (GLED), ligustrazine (LIG), mailuoning, puerarin, safflower, shuxuetong, safflower yellow sodium chloride, and xueshuantong (XST), can significantly improve the clinical effectiveness in patients with DR, while LIG, XST, and GLED can improve vision. The strength of the evidence ranged from high to very low. Outlook: In patients with DR, the combination of multiple injected Traditional Chinese Medicines is more effective than conventional treatment; some of these medicines may also improve visual acuity. This study may provide a good resource and reference for the selection of adjuvant therapy for DR.

Pyroptosisin periodontitis: From the intricate interaction with apoptosis, NETosis, and necroptosis to the therapeutic prospects

Periodontitis is highly prevalent worldwide. It is characterized by periodontal attachment and alveolar bone destruction, which not only leads to tooth loss but also results in the exacerbation of systematic diseases. As such, periodontitis has a significant negative impact on the daily lives of patients. Detailed exploration of the molecular mechanisms underlying the physiopathology of periodontitis may contribute to the development of new therapeutic strategies for periodontitis and the associated systematic diseases. Pyroptosis, as one of the inflammatory programmed cell death pathways, is implicated in the pathogenesis of periodontitis. Progress in the field of pyroptosis has greatly enhanced our understanding of its role in inflammatory diseases. This review first summarizes the mechanisms underlying the activation of pyroptosis in periodontitis and the pathological role of pyroptosis in the progression of periodontitis. Then, the crosstalk between pyroptosis with apoptosis, necroptosis, and NETosis in periodontitis is discussed. Moreover, pyroptosis, as a novel link that connects periodontitis with systemic disease, is also reviewed. Finally, the current challenges associated with pyroptosis as a potential therapeutic target for periodontitis are highlighted.

Tetramethylpyrazine Attenuates Cognitive Impairment Via Suppressing Oxidative Stress, Neuroinflammation, and Apoptosis in Type 2 Diabetic Rats

Cognitive dysfunction is an important complication observed in type 2 diabetes mellitus (T2DM) patients. Tetramethylpyrazine (TMP) is known to exhibit anti-diabetic and neuroprotective properties. Therefore, the present study aimed to investigate the possible therapeutic effects of TMP against type 2 diabetes-associated cognitive impairment in rats. High-fat diet (HFD) followed by a low dose of streptozotocin (35 mg/kg) was used to induce diabetes in Sprague-Dawley rats. TMP (20, 40, and 80 mg/kg) and Pioglitazone (10 mg/kg) were administered for 4 weeks. The Morris water maze (MWM) and novel objective recognition task (NOR) tests were used to assess memory function. Fasting blood glucose (FBG), lipid profile, HOMA-IR, glycosylated hemoglobin (HbA1c), and glucose tolerance were measured. Acetylcholinesterase (AChE) and choline acetytransferase (ChAT) activity, acetylcholine (ACh) levels, oxidative stress, apoptotic (Bcl-2, Bax, caspase-3), and inflammatory markers (TNF-α, IL-1β, and NF-kβ) were assessed. BDNF, p-AKT, and p-CREB levels were also measured. In the present work, we observed that treatment of diabetic rats with TMP alleviated learning and memory deficits, improved insulin sensitivity, and attenuated hyperglycemia and dyslipidemia. Furthermore, treatment with TMP increased BDNF, p-Akt, and p-CREB levels, normalized cholinergic dysfunction, and suppressed oxidative, inflammatory, and apoptotic markers in the hippocampus. Collectively, our results suggest that the TMP may be an effective neuroprotective agent in alleviating type 2 diabetes-associated cognitive deficits.

Artesunate and Tetramethylpyrazine Exert Effects on Experimental Cerebral Malaria in a Mechanism of Protein S-Nitrosylation

Cerebral malaria (CM) is caused by Plasmodium falciparum, resulting in severe sequelae; one of its pathogenic factors is the low bioavailability of nitric oxide (NO). Our previous study suggested that the combination of artesunate (AS) and tetramethylpyrazine (TMP) exerts an adjuvant therapeutic effect on the symptoms of experimental CM (ECM) and that NO regulation plays an important role. In the present study, we further verified the effects of AS+TMP on cerebral blood flow (CBF) and detected NO-related indicators. We focused on the role of NO through S-nitrosoproteome based on previous proteomics data and explored the mechanism of AS+TMP for improving pathological ECM symptoms. We observed that AS+TMP reduces adhesion, increases CBF, and regulates NO synthase (NOS) activity, thereby regulating the level of S-nitrosothiols, such as metabolism-related or neuro-associated receptors, for improving ECM symptoms. These results demonstrated that AS+TMP could be an effective strategy in adjuvant therapy of CM.

Retinal microglia polarization in diabetic retinopathy

Microglia, the main immune cell of the central nervous system (CNS), categorized into M1-like phenotype and M2-like phenotype, play important roles in phagocytosis, cell migration, antigen presentation, and cytokine production. As a part of CNS, retinal microglial cells (RMC) play an important role in retinal diseases. Diabetic retinopathy (DR) is one of the most common complications of diabetes. Recent studies have demonstrated that DR is not only a microvascular disease but also retinal neurodegeneration. RMC was regarded as a central role in neurodegeneration and neuroinflammation. Therefore, in this review, we will discuss RMC polarization and its possible regulatory factors in early DR, which will provide new targets and insights for early intervention of DR.

2,3,5,6-Tetramethylpyrazine protects retinal photoreceptors against endoplasmic reticulum stress by modulating ATF4-mediated inhibition of PRP aggregation

Endoplasmic reticulum (ER) stress is a common threat to photoreceptors during the pathogenesis of chronic retinopathies and often results in irreversible visual impairment. 2,3,5,6-Tetramethylpyrazine (TMP), which possesses many beneficial pharmacological activities, is a potential drug that could be used to protect photoreceptors. In the present study, we found that the cellular growth rate of 661 W cells cultured under low glucose conditions was lower than that of control cells, while the G2/M phase of the cell cycle was longer. We further found that the mitochondrial membrane potential (ΔΨm) was lower and that ER stress factor expression was increased in 661 W cells cultured under low glucose conditions. TMP reversed these trends. Visual function and cell counts in the outer nuclear layer (ONL) were low and the TUNEL-positive rate in the ONL was high in a C3H mouse model of spontaneous retinal degeneration. Similarly, visual function was decreased, and the TUNEL-positive rate in the ONL was increased in fasted C57/BL6j mice compared with control mice. On the other hand, ER stress factor expression was found to be increased in the retinas of both mouse models, as shown by reverse transcription real-time PCR (RT-qPCR) and western blotting. TMP reversed the physiological and molecular biological variations observed in both mouse models, and ATF4 expression was enhanced again. Further investigation by using western blotting illustrated that the proportion of insoluble prion protein (PRP) versus soluble PRP was reduced both in vitro and in vivo. Taken together, these results suggest that TMP increased the functions of photoreceptors by alleviating ER stress in vitro and in vivo, and the intrinsic mechanism was the ATF4-mediated inhibition of PRP aggregation. TMP may potentially be used clinically as a therapeutic agent to attenuate the functional loss of photoreceptors during the pathogenesis of chronic retinopathies. KEY MESSAGES: • Already known: TMP is a beneficial drug mainly used in clinic to enhance organ functions, and the intrinsic mechanism is still worthy of exploring. • New in the study: We discovered that TMP ameliorated retinal photoreceptors function via ER stress alleviation, which was promoted by ATF4-mediated inhibition of PRP aggregation. • Application prospect: In prospective clinical practices, TMP may potentially be used in the clinic as a therapeutic agent to attenuate the photoreceptors functional reduction in chronic retinopathies.

Tetramethylpyrazine protects mice retinas against sodium iodate-induced oxidative injury

Purpose

To observe the effects of tetramethylpyrazine (TMP) on mice retinas injured by sodium iodate (NaIO₃).

Methods

Male mice (n = 45) were randomly divided into three groups: the control group (Group C), the NaIO₃-degenerated group (Group I), and the TMP-treated group (TMP group). The Group I mice were intraperitoneally injected with 35 mg/kg NaIO₃. The Group C mice were injected with similar volumes of PBS. The TMP group mice were intraperitoneally injected with 80 mg/kg TMP starting 24 h after NaIO₃ administration once a day for 14 days. Fundus photography, optical coherence tomography (OCT), electroretinography (ERG), hematoxylin and eosin (H&E) staining, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, and western blotting were used to assess the effects of TMP on mice retinas at day 3, 7, and 14 after NaIO₃ administration.

Results

TMP effectively prevented the decrease in the thicknesses of the retinas and the outer nuclear layer (ONL), and effectively alleviated the functional decline in the retinas after NaIO₃ administration. TMP significantly decreased the number of TUNEL-positive cells in retinas. In addition, TMP rapidly increased the expression of Nrf2 and HO-1 and decreased BAX expression in mice retinas after NaIO₃ injection.

Conclusions

TMP alleviates morphological and functional retinal damage in mice exposed to NaIO₃ and reduces retinal apoptosis.

Tetramethylpyrazine alleviates iron overload damage in vascular endothelium via upregulating DDAHII expression

Iron overload causes vascular endothelium damage. It has been thought to relate excessive reactive oxygen species (ROS) generation. Tetramethylpyrazine (TMP), an active ingredient of Ligusticum chuanxiong Hort, protects various cells by inhibiting oxidative stress and cascade reaction of apoptosis. However, whether TMP can increase DDAHII activity and expression against endothelial cell damage induced by iron overload, and the protective mechanism has not been elucidated. In this study, 50 μM iron dextran and 25 μM TMP were used to co-treat HUVECs for 48 h. TMP could increase cell viability and decrease LDH activity, enhance DDAHII expression and activity, p-eNOS/eNOS ratio, NO content, and reduce ADMA level. TMP also showed a strong antioxidant activity with inhibited ROS generation and oxidative stress. Moreover, TMP attenuated mitochondrial membrane potential loss, inhibited mitochondrial permeability transition pore openness, and decreased apoptosis induced by iron overload. While mentioned above, the protective effects of TMP were abolished with the addition of pAD/DDAHII-shRNA. The effects of TMP against iron overload were similar to the positive control groups, L-arginine, a competitive substrate of ADMA, or edaravone, free radical scavenger. These results signify that TMP alleviated iron overload damage in vascular endothelium via ROS/ADMA/ DDAHII/eNOS/NO pathway.

Tetramethylpyrazine (TMP) protects rats against acute pancreatitis through NF-κB pathway

Acute pancreatitis (AP) is a digestive disease characterized by pancreatic inflammation. Tetramethylpyrazine (TMP) has been effectively used to ameliorate the damage on intestinal mucosa injury in rats with acute necrotizing pancreatitis (ANP). We aim to study the protective effect of TMP on caerulein-induced AP and to explore the possible mechanism. The mice randomized into control and different experimental groups. AP was induced in mice by 6-hourly intraperitoneal (i.p) injections of caerulein (50 μg/kg at 1 h interval). TMP (i.p, 10 mg/kg, 1 h interval) was administered 3 h before caerulein injection. Administration of TMP attenuated the severity of AP as shown by the histopathology, reduced serum amylase activity and pro-inflammatory cytokines TNF-α and IL-6. Further, TMP enhances the beneficial effect by reducing caerulein-induced NF-κB activation and inducing cell apoptosis in pancreas. Therefore, inhibition of nuclear factor-kappa B(NF-κB) signals by TMP represents a potential therapeutic strategy for the treatment of acute pancreatitis.

Retinal Transcriptome Analysis in the Treatment of Endotoxin-Induced Uveitis with Tetramethylpyrazine Eye Drops

Purpose: To investigate retinal gene expression of tetramethylpyrazine (TMP) eye drop-treated endotoxin-induced uveitis (EIU) in mice and to explore the mechanisms. Methods: The inflammatory signs of the anterior segment were evaluated, and clinical scores were graded. The retinal transcriptome from the TMP eye drop-treated and the untreated mice was identified by RNA sequencing (RNA-seq) strategy. Differentially expressed genes (DEGs) were validated by real-time PCR. The protein-protein interaction was analyzed using the STRING software. Results: Compared with the TMP-treated group, the inflammatory responses of the untreated control group were much severe and clinical score was remarkably higher (P < 0.001) at 24 h after lipopolysaccharide administration. RNA-seq assay identified 407 DEGs, among which 356 were upregulated and 51 were downregulated. There were 12 upregulated gene ontology terms enriched and 27 upregulated pathways. Seven DEGs, including inflammation-related, complement system-related, and interferon-related genes, were validated using quantitative PCR. Conclusions: TMP exerted anti-inflammatory effect in EIU. Local application of TMP inhibited retinal inflammatory response by regulating the inflammation-related genes, suggesting that TMP may be a potential novel therapeutic drug for ocular inflammation.

A derivative of betulinic acid protects human Retinal Pigment Epithelial (RPE) cells from cobalt chloride-induced acute hypoxic stress

The Retinal Pigment Epithelium (RPE) is a monolayer of cells located above the choroid. It mediates human visual cycle and nourishes photoreceptors. Hypoxia-induced oxidative stress to RPE is a vital cause of retinal degeneration such as the Age-related Macular Degeneration. Most of these retinal diseases are irreversible with no efficient treatment, therefore protecting RPE cells from hypoxia stress is an important way to prevent or slow down the progression of retinal degeneration. Betulinic acid (BA) and betulin (BE) are pentacyclic triterpenoids with anti-oxidative property, but little is known about their effect on RPE cells. We investigated the protective effect of BA, BE and their derivatives against cobalt chloride-induced hypoxia stress in RPE cells. Human ARPE-19 cells were exposed to BA, BE and their eighteen derivatives (named as H3H20) that we customized through replacing moieties at C3 and C28 positions. We found that cobalt chloride reduced cell viability, increased Reactive Oxygen Species (ROS) production as well as induced apoptosis and necrosis in ARPE-19 cells. Interestingly, the pretreatment of 3-O-acetyl-glycyl- 28-O-glycyl-betulinic acid effectively protected cells from acute hypoxia stress induced by cobalt chloride. Our immunoblotting results suggested that this derivative attenuated the cobalt chloride-induced activation of Akt, Erk and JNK pathways. All findings were further validated in human primary RPE cells. In summary, this BA derivate has protective effect against the acute hypoxic stress in human RPE cells and may be developed into a candidate agent effective in the prevention of prevalent retinal diseases.

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.

Tetramethylpyrazine Protects Against Early Brain Injury and Inhibits the PERK/Akt Pathway in a Rat Model of Subarachnoid Hemorrhage

Neuronal apoptosis is a potentially fatal pathological process that occurs in early brain injury (EBI) after subarachnoid hemorrhage (SAH). There is an urgent need to identify effective therapeutics to alleviate neuronal apoptosis. Tetramethylpyrazine (TMP), as an important component of the Chinese traditional medicinal herb Ligusticum wallichii, has been widely used in China to treat cerebral ischemic injury and confer neuroprotection. In the present work, we investigate whether TMP can reduce EBI following SAH in rats, specifically via inactivating the PERK/Akt signaling cascade. One hundred twenty-five male Sprague-Dawley rats were used in the present study. TMP was administered by intravenous (i.v.) injection, and the Akt inhibitor MK2206 was injected intracerebroventricularly (i.c.v.). SAH grade, neurological scores, and brain water content were measured 24 h after SAH. Neuronal apoptosis was visualized by Fluoro-Jade C (FJC) staining. Western blotting was used to measure the levels of PERK, p-PERK, eIF2α, p-eIF2α, Akt, p-Akt, Bcl-2, Bax, and cleaved caspase-3. Our results showed that TMP effectively reduced neuronal apoptosis and improved neurobehavioral deficits 24 h after SAH. Administration of TMP reduced the abundance of p-PERK and p-eIF2α. In addition, TMP increased the p-Akt level and the Bcl-2/Bax ratio and decreased the level of cleaved caspase-3. The selective Akt inhibitor MK2206 abolished the anti-apoptotic effect of TMP at 24 h after SAH. Collectively, these results indicate that Akt-related anti-apoptosis through the PERK pathway is a major, potent mechanism of EBI. Further investigation of this pathway may provide a basis for the development of TMP as a clinical treatment.

Antioxidant and Anti-Inflammatory Effects of Blueberry Anthocyanins on High Glucose-Induced Human Retinal Capillary Endothelial Cells

Blueberries possess abundant anthocyanins, which benefit eye health. The purpose of this study was to explore the protective functional role of blueberry anthocyanin extract (BAE) and its predominant constituents, malvidin (Mv), malvidin-3-glucoside (Mv-3-glc), and malvidin-3-galactoside (Mv-3-gal), on high glucose- (HG-) induced injury in human retinal capillary endothelial cells (HRCECs). The results showed that BAE, Mv, Mv-3-glc, and Mv-3-gal enhanced cell viability (P < 0.05 versus the HG group at 24 h); decreased the reactive oxygen species (ROS, P < 0.01 versus the HG group both at 24 and 48 h); and increased the enzyme activity of catalase (CAT) and superoxide dismutase (SOD) (P < 0.05 versus the HG group both at 24 and 48 h). Mv could greatly inhibit HG-induced Nox4 expression both at 24 and 48 h (P < 0.05), while BAE and Mv-3-gal downregulated Nox4 only at 48 h (P < 0.05). Mv, Mv-3-glc, and Mv-3-gal also changed nitric oxide (NO) levels (P < 0.05). BAE and Mv-3-glc also influenced angiogenesis by decreasing the vascular endothelial cell growth factor (VEGF) level and inhibiting Akt pathway (P < 0.05). Moreover, Mv and Mv-3-glc inhibited HG-induced intercellular adhesion molecule-1 (ICAM-1, P < 0.001) and nuclear factor-kappa B (NF-κB) (P < 0.05). It indicated that blueberry anthocyanins protected HRCECs via antioxidant and anti-inflammatory mechanisms, which could be promising molecules for the development of nutraceuticals to prevent diabetic retinopathy.

Neuroprotective effect of tetramethylpyrazine against all-trans-retinal toxicity in the differentiated Y-79 cells via upregulation of IRBP expression

It is estimated that abnormal accumulation of all-trans-retinal (atRAL) is a leading cause of photoreceptor degeneration in retinal degenerative diseases. Deficiency of interphotoreceptor retinoid-binding protein (IRBP), a retinoid transporter in the visual cycle, is responsible for the impaired clearance of atRAL and results in atRAL toxicity in retina. Therefore, IRBP has been proposed to be a potent target in preventing atRAL-induced photoreceptor degeneration. In this study, the neuroprotective effect of tetramethylpyrazine (TMP) against atRAL toxicity in the differentiated Y-79 cells, a in vitro model of photoreceptor, was first investigated. Our findings showed that atRAL could induce cytotoxicity, oxidative/nitrosative stresses, apoptosis and leukostasis in the differentiated Y-79 cells; however, the pre-treatment of TMP significantly attenuated such effects in a dose-dependent manner. Furthermore, our results indicated that TMP exerted its neuroprotective effect mainly through upregulating IRBP expression. The present study significantly contributes to better understanding the important role of IRBP in retinal degenerative diseases and forms the basis of the therapeutic development of TMP in such diseases in the future.

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.

ESE1 is Associated with Neuronal Apoptosis in Lipopolysaccharide Induced Neuroinflammation

Neuronal apoptosis induced by the over-activation of microglia during neuroinflammation contributes to the pathology of central nervous system (CNS) degenerative diseases. ESE1 regulates apoptosis of intestinal epithelial cells in ulcerative colitis via accelerating NF-κB activation. NF-κB activation participates in neuronal apoptosis. However, the expression and functions of ESE1 in neuronal apoptosis during CNS inflammatory response remain unclear. In present study, ESE1 expression significantly increased in cerebral cortex after lipopolysaccharide (LPS) intracerebroventricular injection. Immunofluorescence staining indicated that ESE1 was located in neurons. Furthermore, there was a concomitant up-regulation of apoptotic markers including active caspase-3, BAX and decreased expression of anti-apoptosis protein Bcl-2. In vitro, ESE1 depletion in cortical primary neurons inhibited active caspase-3 and BAX expression as well as lactate dehydrogenase (LDH) release with up-regulation of Bcl-2, while ESE1 overexpression can exert opposite effects, indicating that ESE1 promoted neuronal apoptosis induced by LPS or LPS exposed microglia conditioned media (CM). ESE1 accelerated NF-κB activation in neurons with CM treatment. Collectively, all these data suggested that ESE1 might boost neuronal apoptosis during neuroinflammation via up-regulating NF-κB activation. These findings have implications on the potential target of ESE1 in CNS inflammation treatment.