Curcumin inhibits high glucose‑induced inflammatory injury in human retinal pigment epithelial cells through the ROS‑PI3K/AKT/mTOR signaling pathway

Alleviation of Diabetic Retinopathy by Glucose-Triggered Delivery of Vitamin D via Dextran-Gated Functionalized Mesoporous Silica Nanoparticles

Diabetic retinopathy (DR) is the most common retinal disorder, developed in 35% of patients with diabetes mellitus. Lower serum levels of 25-hydroxyvitamin D are associated with the increased risk of developing DR. High doses of the active form of vitamin D (VD), on the contrary, for a long period of time may lead to hypercalcemia and an imbalance in the regulation of bone metabolism. Herein, we studied the efficacy of dextran-gated carboxyphenylboronic acid (CPBA)-functionalized mesoporous silica nanoparticles (MSNs) for glucose-sensitive delivery of 1,25-dihydroxyvitamin D3 to modulate cellular oxidative stress and inflammation for managing DR. The physical adsorption technique was employed to load VD onto nanoparticles (263.63 μg/mg (w/w)). In the presence of glucose, the dextran molecules detach from pores, allowing VD to release since glucose has 1,2-cis diol groups which have very high affinity to CPBA. Approximately 75% of VD was released upon exposure to 25 mM glucose at a time point of 10 h, demonstrating glucose-responsive delivery. Furthermore, MSN-CPBA was able to deliver VD in a glucose-dependent manner and improve the bioavailability of VD. In high-glucose-supplemented human retinal cells, MSN-CPBA increased the bioavailability of VD and reduced cellular oxidative stress and inflammation. The results suggested that the VD-loaded nanocarrier exerted remarkable therapeutic capacity in reducing the risk of developing DR. By using MSN-CPBA as a delivery platform with dextran gating, the research proposes an effective treatment approach for improving the bioavailability and effectiveness of a hydrophobic molecule in the treatment of DR.

Alcohol-induced liver injury in signalling pathways and curcumin's therapeutic potential

Confronting the profound public health concern of alcohol-induced liver damage calls for inventive therapeutic measures. The social, economic, and clinical ramifications are extensive and demand a comprehensive understanding. This thorough examination uncovers the complex relationship between alcohol intake and liver damage, with a special emphasis on the pivotal roles of the Toll-like receptor 4 (TLR4)/NF-κB p65 and CYP2E1/ROS/Nrf2 signalling networks. Different alcohol consumption patterns, determined by a myriad of factors, have significant implications for liver health, leading to a spectrum of adverse effects. The TLR4/NF-κB p65 pathway, a principal regulator of inflammation and immune responses, significantly contributes to various disease states when its balance is disrupted. Notably, the TLR4/MD-2-TNF-α pathway has been linked to non-alcohol related liver disease, while NF-κB activation is associated with alcohol-induced liver disease (ALD). The p65 subunit of NF-κB, primarily responsible for the release of inflammatory cytokines, hastens the progression of ALD. Breakthrough insights suggest that curcumin, a robust antioxidant and anti-inflammatory compound sourced from turmeric, effectively disrupts the TLR4/NF-κB p65 pathway. This heralds a new approach to managing alcohol-induced liver damage. Initial clinical trials support curcumin's therapeutic potential, highlighting its ability to substantially reduce liver enzyme levels. The narrative surrounding alcohol-related liver injury is gradually becoming more intricate, intertwining complex signalling networks such as TLR4/NF-κB p65 and CYP2E1/ROS/Nrf2. The protective role of curcumin against alcohol-related liver damage marks the dawn of new treatment possibilities. However, the full realisation of this promising therapeutic potential necessitates rigorous future research to definitively understand these complex mechanisms and establish curcumin's effectiveness and safety in managing alcohol-related liver disorders.

Complementary Approaches to Retinal Health Focusing on Diabetic Retinopathy

Diabetes mellitus affects carbohydrate homeostasis but also influences fat and protein metabolism. Due to ophthalmic complications, it is a leading cause of blindness worldwide. The molecular pathology reveals that nuclear factor kappa B (NFκB) has a central role in the progression of diabetic retinopathy, sharing this signaling pathway with another major retinal disorder, glaucoma. Therefore, new therapeutic approaches can be elaborated to decelerate the ever-emerging "epidemics" of diabetic retinopathy and glaucoma targeting this critical node. In our review, we emphasize the role of an improvement of lifestyle in its prevention as well as the use of phytomedicals associated with evidence-based protocols. A balanced personalized therapy requires an integrative approach to be more successful for prevention and early treatment.

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.

The signaling pathways of traditional Chinese medicine in treating diabetic retinopathy

Diabetic retinopathy (DR) is one of the common diabetic microvascular complications that occurs in the eyes and is closely associated with vision loss in working adults. However, the clinical treatment of DR is limited or accompanied by a large number of complications. Therefore, the development of new drugs for the treatment of DR is urgently needed. Traditional Chinese medicine (TCM) is widely used to treat DR in China, and its multi-pathway and multi-level characteristics can effectively address the complex pathogenesis of DR. Growing evidence suggests that inflammation, angiogenesis, and oxidative stress are the core pathological mechanisms in the development of DR. This study innovatively considers the aforementioned processes as the fundamental unit and sheds light on the molecular mechanisms and potential of TCM against DR in terms of signaling pathways. The results showed that NF-κB, MAPK/NF-κB, TLR4/NF-κB, VEGF/VEGFR2, HIF-1α/VEGF, STAT3, and Nrf2/HO-1 are the key signaling pathways for the treatment of DR by TCMs, which involved curcumolide, erianin, quercetin, blueberry anthocyanins, puerarin, arjunolic acid, ethanol extract of Scutellaria barbata D. Don, Celosia argentea L. extract, ethanol extract of Dendrobium chrysotoxum Lindl., Shengpuhuang-tang, and LuoTong formula. The purpose of this review is to update and summarize the signaling pathways of TCM in the treatment of DR and provide ideas for the development of new drugs against DR in the future.

Impairment of insulin signaling pathway PI3K/Akt/mTOR and insulin resistance induced AGEs on diabetes mellitus and neurodegenerative diseases: a perspective review

Insulin resistance is common in type 2 diabetes mellitus (T2DM), neurodegenerative diseases, cardiovascular diseases, kidney diseases, and polycystic ovary syndrome. Impairment in insulin signaling pathways, such as the PI3K/Akt/mTOR pathway, would lead to insulin resistance. It might induce the synthesis and deposition of advanced glycation end products (AGEs), reactive oxygen species, and reactive nitrogen species, resulting in stress, protein misfolding, protein accumulation, mitochondrial dysfunction, reticulum function, and metabolic syndrome dysregulation, inflammation, and apoptosis. It plays a huge role in various neurodegenerative diseases like Parkinson's disease, Alzheimer's disease, Huntington's disease, and Amyloid lateral sclerosis. In this review, we intend to focus on the possible effect of insulin resistance in the progression of neurodegeneration via the impaired P13K/Akt/mTOR signaling pathway, AGEs, and receptors for AGEs.

An update on molecular mechanisms of curcumin effect on diabetes

Owing to its prevalent nature, diabetes mellitus has become one of the most serious endocrine illnesses affecting a patient's quality of life due to the manifestation of side effects such as cardiovascular diseases, retinopathy, neuropathy, and nephropathy. Curcumin ((1E, 6E) 21, 7-bis (4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), a major compound of turmeric, has been used in conventional medicine because of its safe nature and cost-effectiveness to meliorate diabetes and its comorbidities. These effects have also been observed in rodent models of diabetes resulting in a reduction of glycemia and blood lipids. Both the preventive and therapeutic activities of this compound are due to its antioxidant and anti-inflammatory characteristics. Furthermore, preclinical outcomes and clinical investigation demonstrate that the use of curcumin neutralizes insulin resistance, obesity, and hyperglycemia. Despite the many benefits of curcumin, its two limiting factors, solubility and bioavailability, remain a challenge for researchers; therefore, several methods such as drug formulation, nano-drug delivery, and the use of curcumin analogs have been developed to deliver curcumin and increase its bioavailability. PRACTICAL APPLICATIONS: The rise of people with type 2 diabetes has become a major concern at the global healthcare level. The best diabetes treatments today are anti-diabetic drug administration, lifestyle-related interventions (such as healthy eating and daily physical activity), arterial pressure detection, and fat control. The polyphenol curcumin, found in turmeric, can promote health by acting on a variety of cellular signaling pathways. This review article discusses curcumin and its role in the treatment of diabetes.

mTOR Signalling Pathway: A Potential Therapeutic Target for Ocular Neurodegenerative Diseases

Recent advances in the research of the mammalian target of the rapamycin (mTOR) signalling pathway demonstrated that mTOR is a robust therapeutic target for ocular degenerative diseases, including age-related macular degeneration (AMD), diabetic retinopathy (DR), and glaucoma. Although the exact mechanisms of individual ocular degenerative diseases are unclear, they share several common pathological processes, increased and prolonged oxidative stress in particular, which leads to functional and morphological impairment in photoreceptors, retinal ganglion cells (RGCs), or retinal pigment epithelium (RPE). mTOR not only modulates oxidative stress but is also affected by reactive oxygen species (ROS) activation. It is essential to understand the complicated relationship between the mTOR pathway and oxidative stress before its application in the treatment of retinal degeneration. Indeed, the substantial role of mTOR-mediated autophagy in the pathogenies of ocular degenerative diseases should be noted. In reviewing the latest studies, this article summarised the application of rapamycin, an mTOR signalling pathway inhibitor, in different retinal disease models, providing insight into the mechanism of rapamycin in the treatment of retinal neurodegeneration under oxidative stress. Besides basic research, this review also summarised and updated the results of the latest clinical trials of rapamycin in ocular neurodegenerative diseases. In combining the current basic and clinical research results, we provided a more complete picture of mTOR as a potential therapeutic target for ocular neurodegenerative diseases.

Targeting mTOR Signaling in Type 2 Diabetes Mellitus and Diabetes Complications

The mechanistic target of rapamycin (mTOR) is a pivotal regulator of cell metabolism and growth. In the form of two different multi-protein complexes, mTORC1 and mTORC2, mTOR integrates cellular energy, nutrient and hormonal signals to regulate cellular metabolic homeostasis. In type 2 diabetes mellitus (T2DM) aberrant mTOR signaling underlies its pathological conditions and end-organ complications. Substantial evidence suggests that two mTOR-mediated signaling schemes, mTORC1-p70S6 kinase 1 (S6K1) and mTORC2-protein kinase B (AKT), play a critical role in insulin sensitivity and that their dysfunction contributes to development of T2DM. This review summaries our current understanding of the role of mTOR signaling in T2DM and its associated complications, as well as the potential use of mTOR inhibitors in treatment of T2DM.

The interplay of autophagy and oxidative stress in the pathogenesis and therapy of retinal degenerative diseases

Oxidative stress is mainly caused by intracellular reactive oxygen species (ROS) production, which is highly associated with normal physiological homeostasis and the pathogenesis of diseases, particularly ocular diseases. Autophagy is a self-clearance pathway that removes oxidized cellular components and regulates cellular ROS levels. ROS can modulate autophagy activity through transcriptional and posttranslational mechanisms. Autophagy further triggers transcription factor activation and degrades impaired organelles and proteins to eliminate excessive ROS in cells. Thus, autophagy may play an antioxidant role in protecting ocular cells from oxidative stress. Nevertheless, excessive autophagy may cause autophagic cell death. In this review, we summarize the mechanisms of interaction between ROS and autophagy and their roles in the pathogenesis of several ocular diseases, including glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR), and optic nerve atrophy, which are major causes of blindness. The autophagy modulators used to treat ocular diseases are further discussed. The findings of the studies reviewed here might shed light on the development and use of autophagy modulators for the future treatment of ocular diseases.

Antioxidant activity of Curcumin

In the past few years, multiple drugs have been produced from traditional raw materials and recent pandemic disease COVID-19 once again research on this matter is being conducted to determine potential therapeutic purposes of different Ayurvedic Indian medicines and herbs. One such medicinal herb is Curcuma longa. Curcumin is strong antioxidant, anti-inflammatory, antispasmodic, antiangiogenic, anti-carcinogenic, as shown by multiple in vitro and in vivo studies. The action of the growth factor receptors is inhibited by curcumin. The anti-inflammatory effect of curcumin is obtained on the cytokines, proteolytic enzymes, eicosanoids, and lipid mediators. The superoxide radicals, nitric oxide and hydrogen peroxide, are sifted by curcumin, while lipid peroxidation is inhibited. Such properties of the compound thus form the foundation for its various therapeutic and pharmacological effects could also hold antiviral properties including COVID-19. The aim of this research is to summarize the updated pharmacological activities of curcumin.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

Recent Advances and Disputes About Curcumin in Retinal Diseases

Curcumin belongs to the group of so-called phytocompounds, biologically active molecules produced by plants exerting a beneficial effect on health. Curcumin shows a wide spectrum of different properties, being an anti-inflammatory, antioxidant, antimicrobial and antimutagenic molecule. The purpose of the review is to examine what literature reported on the characteristics of curcumin, particularly, on the beneficial and controversial aspects of this molecule, aiming for a better therapeutic management of retinal diseases. The retina is a constant target of oxidative stress, this tissue being characterized by cells rich in mitochondria and by vessels and being, obviously, continuously reached from photons affecting its layers. Particularly, the retinal ganglion cells and the photoreceptors are extremely sensitive to oxidative stress damage and it is well known that an imbalance in reactive oxygen species is often involved in several retinal diseases, such as uveitis, age-related macular degeneration, diabetic retinopathy, central serous chorioretinopathy, macular edema, retinal ischemia-reperfusion injury, proliferative vitreoretinopathy, hereditary tapeto-retinal degenerations, and retinal and choroidal tumors. To date, several studies suggest that oral treatment with curcumin is generally well tolerated in humans and, in addition, it seems to have no negative effects: therefore, curcumin is a promising candidate as a retinal disease therapy. Unfortunately, the primary limitation of curcumin is represented by its poor bioavailability, in fact only a minimal fraction of this substance can reach the blood stream in the form of a biologically active compound. However, many steps have been made in several fields. In the future, it is expected that the strategies developed until now to allow curcumin to reach the target tissues in adequate concentrations could be ameliorated and, above all, large in vivo studies on humans are needed to demonstrate the total safety of these compounds and their effectiveness in different eye diseases.

Network Pharmacology-Based Approach to Comparatively Predict the Active Ingredients and Molecular Targets of Compound Xueshuantong Capsule and Hexuemingmu Tablet in the Treatment of Proliferative Diabetic Retinopathy

Background

Compound Xueshuantong capsule (CXC) and Hexuemingmu tablet (HXMMT) are two important Chinese patent medicines (CPMs) frequently used to treat proliferative diabetic retinopathy (PDR), especially when complicated with vitreous hemorrhage (VH). However, a network pharmacology approach to understand the therapeutic mechanisms of these two CPMs in PDR has not been applied.

Objective

To identify differences in the active ingredients between CXC and HXMMT and to comparatively predict and further analyze the molecular targets shared by these CPMs and PDR. Materials and methods. The differentially expressed messenger RNAs (mRNAs) between normal retinal tissues in healthy individuals and active fibrovascular membranes in PDR patients were retrieved from the Gene Expression Omnibus database. The active ingredients of CXC and HXMMT and the targets of these ingredients were retrieved from the Traditional Chinese Medicine Systems Pharmacology database. The intersections of the CPM (CXC and HXMMT) targets and PDR targets were determined. Then, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed, and the ingredient-target networks, protein-protein interaction networks, and KEGG-target (KEGG-T) networks were constructed.

Results

CXC contains 4 herbs, and HXMMT contains 19. Radix salviae is the only herb common to both. CXC had 34 potential therapeutic targets in PDR, while HXMMT had these 34 and 10 additional targets. Both CPMs shared the following main processes: response to reactive oxygen species and oxidative stress, regulation of blood vessel diameter and size, vasoconstriction, smooth muscle contraction, hemostasis, and blood coagulation. The shared pathways included the AGE-RAGE signaling pathway in diabetic complications, TNF signaling pathway, relaxin signaling pathway, and IL-17 signaling pathway.

Conclusions

Both CXC and HXMMT include components effective at treating PDR and affect the following main processes: response to reactive oxygen species and oxidative stress, regulation of blood vessels, and blood coagulation. Radix salviae, the only herb common to both CPMs, contains many useful active ingredients. The PDR-CXC and PDR-HXMMT networks shared 34 common genes (RELA, HSPA8, HSP90AA, HSP90AB1, BRCA, EWSR1, CUL7, HNRNPU, MYC, CTNNB1, MDM2, YWHAZ, CDK2, AR, FN1, HUWE1, TP53, TUBB, EP300, GRB2, VCP, MCM2, EEF1A1, NTRK1, TRAF6, EGFR, PRKDC, SRC, HDAC5, APP, ESR1, AKT1, UBC, and COPS5), and the PDR-HXMMT network has 10 additional genes (RNF2, VNL, RPS27, COPS5, XPO1, PARP1, RACK1, YWHAB, and ITGA4). The top 5 pathways with the highest gene ratio in both networks were the AGE-RAGE signaling pathway in diabetic complications, TNF signaling pathway, relaxin signaling pathway, IL-17 signaling pathway, and focal adhesion. Additional pathways such as neuroactive ligand-receptor interaction, chemokine signaling pathway, and AMPK signaling pathway were enriched with HXMMT targets. Thus, HXMMT has more therapeutic targets shared by different active ingredients and more abundant gene functions than CXC, which may be two major reasons why HXMMT is more strongly recommended than CXC as an auxiliary treatment for new-onset VH secondary to PDR. However, the underlying mechanisms still need to be further explored.

Therapeutic potential of curcumin in diabetic retinopathy (Review)

Diabetic retinopathy (DR) is a type of retinal microangiopathy caused by diabetes mellitus. It has become the leading cause of blindness among working individuals worldwide. DR is becoming increasingly common among younger diabetic patients and there is a need for lifelong treatment. The pathogenic mechanisms of DR are influenced by a number of factors, such as hyperglycemia, hyperlipidemia, inflammatory response and oxidative stress, among others. Currently, the treatment methods for DR mainly include retinal photocoagulation, vitrectomy, or anti‑vascular endothelial growth factor (VEGF) therapy. However, these methods have some disadvantages and limitations. Therefore, it is a matter of great interest and urgency to discover drugs that can target the pathogenesis of DR. Since ancient times, traditional Chinese medicine practitioners have accumulated extensive experiences in the use of Chinese herbal medicine for the prevention and treatment of diseases. In the theory of traditional Chinese medicine, curcumin has the effects of promoting blood circulation and relieving pain. A number of studies have also demonstrated that curcumin has multiple biological activities, including exerting anti‑apoptotic, anti‑inflammatory, antioxidant and antitumor properties. In recent years, studies have also confirmed that curcumin can prevent a variety of diabetic complications, including diabetic nephropathy (DN). However, the preventive and curative effects of curcumin on DR and its mechanisms of action have not yet been fully elucidated. The present review aimed to explore the therapeutic potential of curcumin in diabetes mellitus and DR.

The Multifaced Actions of Curcumin in Pregnancy Outcome

Curcumin, also known as diferuloylmethane, is the main polyphenolic substance present in the rhizomes of Curcuma longa L. This plant showed many beneficial effects and has been used since ancient times for both food and pharmaceutical purposes. Due to its pleiotropic functions, curcumin consumption in the human diet has become very common thanks also to the fact that this natural compound is considered quite safe as it does not have serious side effects. Its functions as an anti-inflammatory, anti-oxidant, neuroprotective, immunomodulatory, anti-toxicant, anti-apoptotic, and anti-diabetic compound are already known and widely demonstrated. There are numerous studies concerning its effects on various human pathologies including cancer, diabetes and arthritis while the studies on curcumin during pregnancy have been performed only in animal models. Data concerning the role of curcumin as anti-inflammatory compound suggest a possible use of curcumin in managing pregnancy complications such as Preeclampsia (PE), Gestational Diabetes Mellitus (GDM), Fetal Growth Restriction (FGR), PreTerm Birth (PTB), and exposure to toxic agents and pathogens. The aim of this review is to present data to support the possible use of curcumin in clinical trials on human gestation complications.

The Beneficial Effects of Principal Polyphenols from Green Tea, Coffee, Wine, and Curry on Obesity

Several epidemiological studies and clinical trials have reported the beneficial effects of green tea, coffee, wine, and curry on human health, with its anti-obesity, anti-cancer, anti-diabetic, and neuroprotective properties. These effects, which have been supported using cell-based and animal studies, are mainly attributed to epigallocatechin gallate found in green tea, chlorogenic acid in coffee, resveratrol in wine, and curcumin in curry. Polyphenols are proposed to function via various mechanisms, the most important of which is related to reactive oxygen species (ROS). These polyphenols exert conflicting dual actions as anti- and pro-oxidants. Their anti-oxidative actions help scavenge ROS and downregulate nuclear factor-κB to produce favorable anti-inflammatory effects. Meanwhile, pro-oxidant actions appear to promote ROS generation leading to the activation of 5′-AMP-activated protein kinase, which modulates different enzymes and factors with health beneficial roles. Currently, it remains unclear how these polyphenols exert either pro- or anti-oxidant effects. Similarly, several human studies showed no beneficial effects of these foods, and, by extension polyphenols, on obesity. These inconsistencies may be attributed to different confounding study factors. Thus, this review provides a state-of-the-art update on these foods and their principal polyphenol components, with an assumption that it prevents obesity.

Role of mTOR Complex 1 Signaling Pathway in the Pathogenesis of Diabetes Complications; A Mini Review

The mammalian target of rapamycin (mTOR) is an evolutionarily conserved serine/threonine-protein kinase that senses and combines various environmental signals to regulate the growth and homeostasis of human cells. This signaling pathway synchronizes many critical cellular processes and is involved in an increasing number of pathological conditions such as diabetes, cancer, obesity, and metabolic syndrome. Here, we review different complications of diabetes that are associated with mTOR complex 1 imbalance. We further discuss pharmacological approaches to treat diabetes complications linked to mTOR deregulation.

Exploring the Mechanism of Action Compound-Xueshuantong Capsule in Diabetic Retinopathy Treatment Based on Network Pharmacology

Materials and Methods

The components with oral bioavailability ≥30% and drug similarity ≥0.18 were screened by the Traditional Chinese Medicine System Pharmacology Database and Analysis Platform (TCMSP), and the effective grouping of Compound-Xueshuantong Capsule was obtained. At the same time, the targets of each drug active component in the Compound-Xueshuantong Capsule were obtained by searching the TCMSP. The effective components and targets of the Compound-Xueshuantong Capsule were annotated by the UniProt database, and the disease treatment targets were searched by the GeneCards database. The disease treatment target is intersected with the drug target and the Wayne diagram is drawn by VennDiagram. The active ingredient targets of the intersection and Compound-Xueshuantong Capsule were inputted into Cytoscape 3.7.2 software to construct the active ingredient-target-disease interaction network. The above targets were inputted into the String database for protein-protein interaction network prediction. Finally, by using the DAVID database, GO and KEGG enrichment analysis was carried out to reveal the potential signal pathway of the Compound-Xueshuantong Capsule in diabetic retinopathy treatment.

Results

93 active components of the Compound-Xueshuantong Capsule and 92 targets for treating diabetic retinopathy were screened. The main active components of the Compound-Xueshuantong Capsule in treating diabetic retinopathy were quercetin, luteolin, kaempferol, beta-sitosterol, isorhamnetin, and tanshinone IIa. The effect of the Compound-Xueshuantong Capsule on diabetic retinopathy may be related to IL6, EFGR, CASP3, and VEGFA. In addition, the treatment of diabetic retinopathy mainly involves in the regulation of nuclear receptors and transcription factors in vivo. The target of the Compound-Xueshuantong Capsule in diabetic retinopathy treatment is significantly enriched in the AGE-RAGE signal pathway, TNF signal pathway, HIF-1 signal pathway, and VEGF signal pathway in diabetic complications.

Conclusion

Compound-Xueshuantong Capsule can treat diabetic retinopathy through multitarget, multipathway, and multipathway regulation of the biomolecular network. The potential biological mechanism of the Compound-Xueshuantong Capsule in diabetic retinopathy treatment may be related to the AGE-RAGE signal pathway, TNF signal pathway, HIF-1 signal pathway, and VEGF signal pathway in diabetic complications, but these findings still need to be confirmed by further clinical research.

Oxidative Stress and Vascular Dysfunction in the Retina: Therapeutic Strategies

Many retinal diseases, such as diabetic retinopathy, glaucoma, and age-related macular (AMD) degeneration, are associated with elevated reactive oxygen species (ROS) levels. ROS are important intracellular signaling molecules that regulate numerous physiological actions, including vascular reactivity and neuron function. However, excessive ROS formation has been linked to vascular endothelial dysfunction, neuron degeneration, and inflammation in the retina. ROS can directly modify cellular molecules and impair their function. Moreover, ROS can stimulate the production of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) causing inflammation and cell death. However, there are various compounds with direct or indirect antioxidant activity that have been used to reduce ROS accumulation in animal models and humans. In this review, we report on the physiological and pathophysiological role of ROS in the retina with a special focus on the vascular system. Moreover, we present therapeutic approaches for individual retinal diseases targeting retinal signaling pathways involving ROS.

Production and Characterization of Anti-Inflammatory Monascus Pigment Derivatives

The prevention and treatment of chronic inflammation using food-derived compounds are desirable from the perspectives of marketing and safety. Monascus pigments, widely used as food additives, can be used as a chronic inflammation treatment. Orange Monascus pigments were produced by submerged fermentation in a 5 L bioreactor, and multiple orange Monascus pigment derivatives with anti-inflammatory activities were synthesized using aminophilic reaction. A total of 41 types of pigment derivatives were produced by incorporating amines and amino acids into the orange pigments. One derivative candidate that inhibited nitric oxide (NO) production in Raw 264.7 cells and exhibited low cell cytotoxicity was identified via in vitro assay. The 2-amino-4 picoline derivative inhibited NO production of 48.4%, and exhibited cell viability of 90.6%. Expression of inducible NO synthase, an important enzyme in the NO synthesis pathway, was suppressed by such a derivative in a dose-dependent manner. Therefore, this derivative has potential as a functional food colorant with anti-inflammatory effects.

Ginkgo biloba extract protects diabetic rats against cerebral ischemia‑reperfusion injury by suppressing oxidative stress and upregulating the expression of glutamate transporter 1

The current study aimed to evaluate the neuroprotective effect of Ginkgo biloba extract (GbE) on the progression of acute cerebral ischemia-reperfusion injury in diabetic rats, and to determine the molecular mechanism associated with this effect. Streptozotocin (STZ) induced diabetic rats were pretreated with GbE (50, 100 and 200 mg/kg/day; intragastric) for 3 weeks. During this period, body weight changes and fasting blood glucose levels were assessed each week. Following pretreatment, rats were subjected to suture occlusion of the middle cerebral artery for 30 min, which was followed by 24 h of reperfusion. Neurological deficits were subsequently evaluated at 2 and 24 h following reperfusion. Rats were sacrificed after 24 h reperfusion, and infarct volume and S100B content were measured to evaluate the neuroprotective effect of GbE. The results of the present study demonstrated that GbE pretreatment improved neurological scores, and reduced cerebral infarct volume and S100B content. Oxidative stress markers, including glutathione (GSH) and superoxide dismutase (SOD) were increased, and malondialdehyde (MDA) contents were reduced following GbE treatment. The levels of p-Akt, p-mTOR and glutamate transporter 1 (GLT1) were observed to be increased in GbE-pretreated rats. These results indicated that GbE pretreatment may serve a protective role against cerebral ischemia-reperfusion injury in diabetic rats by inhibiting oxidative stress reaction, upregulating the expression of Akt/mTOR and promoting GLT1 expression. In conclusion, the current study revealed the protective role and molecular mechanisms of GbE in diabetic rats with cerebral ischemia-reperfusion injury, and may provide novel insight into the future clinical treatment of this condition.

Adjuvant Therapies in Diabetic Retinopathy as an Early Approach to Delay Its Progression: The Importance of Oxidative Stress and Inflammation

Diabetes mellitus (DM) is a progressive disease induced by a sustained state of chronic hyperglycemia that can lead to several complications targeting highly metabolic cells. Diabetic retinopathy (DR) is a multifactorial microvascular complication of DM, with high prevalence, which can ultimately lead to visual impairment. The genesis of DR involves a complex variety of pathways such as oxidative stress, inflammation, apoptosis, neurodegeneration, angiogenesis, lipid peroxidation, and endoplasmic reticulum (ER) stress, each possessing potential therapeutic biomarkers. A specific treatment has yet to be developed for early stages of DR since no management is given other than glycemic control until the proliferative stage develops, offering a poor visual prognosis to the patient. In this narrative review article, we evaluate different dietary regimens, such as the Mediterranean diet, Dietary Pattern to Stop Hypertension (DASH) and their functional foods, and low-calorie diets (LCDs). Nutraceuticals have also been assessed in DR on account of their antioxidant, anti-inflammatory, and antiangiogenic properties, which may have an important impact on the physiopathology of DR. These nutraceuticals have shown to lower reactive oxygen species (ROS), important inflammatory factors, cytokines, and endothelial damage biomarkers either as monotherapies or combined therapies or concomitantly with established diabetes management or nonconventional adjuvant drugs like topical nonsteroidal anti-inflammatory drugs (NSAIDs).

OMICs approaches-assisted identification of macrophages-derived MIP-1γ as the therapeutic target of botanical products TNTL in diabetic retinopathy

Background

Inflammatory reaction in the dysfunction of retinal endotheliocytes has been considered to play a vital role in diabetic retinopathy (DR). Anti-inflammatory therapy so far gains poor outcome as DR treatment. This study aims to identify a novel therapeutic target of DR from the OMICs studies of a traditional anti-DR botanical products TNTL.

Methods

Hyperglycemic mice were treated with TNTL. The anti-hyperglycemic effect of TNTL was validated to confirm the biological consistency of the herbal products from batches. Improvement of DR by TNTL was examined by various assays on the retina. Next-generation transcriptome sequencing and cytokine array was used to identify the therapeutic targets. In vitro study was performed to validate the target.

Results

We observed that TNTL at its high doses possessed anti-hyperglycemic effect in murine type I diabetic model, while at its doses without reducing blood glucose, it suppressed DR incidence. TNTL restored the blood-retina barrier integrity, suppressed retinal neovascularization, and attenuated the retinal ganglion cell degeneration. Transcriptomic analysis on the retina tissue of hyperglycemic mice with or without TNTL revealed that the inflammatory retina microenvironment was significantly repressed. TNTL treatment suppressed pro-inflammatory macrophages in the retina, which resulted in the inactivation of endothelial cell migration, restoration of endothelial cell monolayer integrity, and prevention of leakage. Cytokine array analysis suggested that TNTL could significantly inhibit the secretion of MIP1γ from pro-inflammatory macrophages. Prevention of endothelial dysfunction by TNTL may be mediated by the inhibition of MIP1γ/CCR1 axis. More specifically, TNTL suppressed MIP1γ release from pro-inflammatory macrophages, which in turn inhibited the activation of CCR1-associated signaling pathways in endothelial cells.

Conclusion

Our findings demonstrated that TNTL might be an alternative treatment to DR, and the primary source of potential drug candidates against DR targeting MIP1γ/CCR1 axis in the retinal microenvironment.

Nutraceuticals for the Treatment of Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus and is characterized by degeneration of retinal neurons and neoangiogenesis, causing a severe threat to vision. Nowadays, the principal treatment options for DR are laser photocoagulation, vitreoretinal surgery, or intravitreal injection of drugs targeting vascular endothelial growth factor. However, these treatments only act at advanced stages of DR, have short term efficacy, and cause side effects. Treatment with nutraceuticals (foods providing medical or health benefits) at early stages of DR may represent a reasonable alternative to act upstream of the disease, preventing its progression. In particular, in vitro and in vivo studies have revealed that a variety of nutraceuticals have significant antioxidant and anti-inflammatory properties that may inhibit the early diabetes-driven molecular mechanisms that induce DR, reducing both the neural and vascular damage typical of DR. Although most studies are limited to animal models and there is the problem of low bioavailability for many nutraceuticals, the use of these compounds may represent a natural alternative method to standard DR treatments.