Grape seed proanthocyanidins protect against streptozotocin‑induced diabetic nephropathy by attenuating endoplasmic reticulum stress‑induced apoptosis

Proanthocyanidin offers protection against diabetic nephropathy: elucidation of its mechanism of action using animal models

CONTEXT

Diabetic nephropathy (DN) is a major complication of diabetes mellitus and is the leading cause of kidney disease in patients undergoing renal replacement therapy. DN is associated with an increased risk of death in patients with diabetes. Conventional therapy for DN includes intensive control of blood glucose level and blood pressure and renin-angiotensin system blockade. However, this approach has limited treatment effects on DN. Therefore, identifying novel drugs to delay the progression of DN is urgently needed. Proanthocyanidin (PA) has been shown to exert potentially beneficial effects on DN. However, the protective mechanism and efficacy are yet to be elucidated.

OBJECTIVE

This study evaluates the efficacy and potential mechanisms of PA in animal models of DN.

METHODS

Preclinical studies were searched from Chinese National Knowledge Infrastructure, PubMed, Web of Science, Embase, and Google Scholar databases, with the search deadline of August 2023. Keywords ('diabetic nephropathies', 'nephropathies, diabetic', 'diabetic kidney diseases', 'proanthocyanidin', 'anthocyanidin polymers', 'procyanidins', 'animal*', 'rat', and 'mice') were used to search the databases. RevMan 5.3 was used for statistical analysis.

RESULTS

A total of 22 studies involving 538 animals were included in this analysis. The pooled results indicated that PA therapy significantly improved kidney function and reduced proteinuria and blood glucose levels. The protective mechanism of PA was associated with anti-inflammatory, antioxidant, antifibrotic, and antiapoptotic effects; inhibition of endoplasmic reticulum stress; and alleviation of mitochondrial dysfunction and dyslipidemia.

CONCLUSION

These findings suggest that PA alleviates DN by mediating multiple targets and pathways.

Effects of grape seed proanthocyanidin extract on cholesterol metabolism and antioxidant status in finishing pigs

Grape seed proanthocyanidin extract (GSPE) is a natural polyphenolic compound, which plays an important role in anti-inflammatory and antioxidant. The present study aimed to investigate the effects of GSPE supplementation on the cholesterol metabolism and antioxidant status of finishing pigs. In longissimus dorse (LD) muscle, the data showed that GSPE significantly decreased the contents of total cholesterol (T-CHO) and triglyceride (TG), and decreased the mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR) and Fatty acid synthase (FAS), while increased the mRNA expression of carnitine palmitoyl transferase-1b (CPT1b), peroxisome proliferator-activated receptors (PPARα) and peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α). GSPE also reduced the enzyme activities of HMG-CoAR and FAS, and meanwhile amplified the activity of CPT1b in LD muscle of finishing pigs. Furthermore, dietary GSPE supplementation increased the serum catalase (CAT) and total antioxidant capacity (T-AOC), serum and liver total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) levels, while reduced serum and liver malondialdehyde (MDA) level in finishing pigs. In the liver, Superoxide Dismutase 1 (SOD1), catalase (CAT), glutathione peroxidase 1 (GPX1), Nuclear Factor erythroid 2-Related Factor 2 (NRF2) mRNA levels were increased by GSPE. In conclusion, this study showed that GSPE might be an effective dietary supplement for improving cholesterol metabolism and antioxidant status in finishing pigs.

Grape Seed Proanthocyanidin Ameliorates LPS-induced Acute Lung Injury By Modulating M2a Macrophage Polarization Via the TREM2/PI3K/Akt Pathway

Acute lung injury (ALI) is an acute and progressive pulmonary inflammatory disease that is difficult to cure and has a poor prognosis. Macrophages, which have various phenotypes and diverse functions, play an essential role in the pathogenesis of ALI. Grape seed proanthocyanidin (GSP) has received much attention over several decades, and many biological activities such as anti-apoptotic, antioxidant, and anti-inflammatory have been identified. This study aimed to determine the effect of GSP on lipopolysaccharide (LPS)-induced ALI. In this study, we established an ALI mouse model by tracheal instillation of LPS, and by pre-injection of GSP into mice to examine the effect of GSP on the ALI mouse model. Using H&E staining, flow cytometry, and ELISA, we found that GSP attenuated LPS-induced lung pathological changes and decreased inflammatory cytokine expression in ALI mice. In addition, GSP reduced the recruitment of monocyte-derived macrophages to the lung and significantly promoted the polarization of primary mouse lung macrophages from M1 to M2a induced by LPS. In vitro, GSP also decreased the expression levels of inflammatory cytokines such as TNF-α, IL-6, IL-1β, and M1 macrophage marker iNOS induced by LPS in MH-S cells, while increasing the expression levels of M2a macrophage marker CD206. Bioinformatics analysis identified TREM2 and the PI3K/Akt pathway as candidate targets and signaling pathways that regulate M1/M2a macrophage polarization in ALI, respectively. Furthermore, GSP activated PI3K/Akt and increased TREM2 expression in vivo and in vitro. Meanwhile, GSP's impact on M2a polarization and inflammation suppression was attenuated by the PI3K inhibitor LY294002 or siRNA knockdown TREM2. In addition, GSP-enhanced PI3K/Akt activity was prevented by TREM2 siRNA. In conclusion, this study demonstrated that GSP could ameliorate LPS-induced ALI by modulating macrophage polarization from M1 to M2a via the TREM2/PI3K/Akt pathway.

Endoplasmic reticulum stress in diabetic kidney disease: adaptation and apoptosis after three UPR pathways

Diabetes kidney disease (DKD) is one of the common chronic microvascular complications of diabetes, which has become the most important cause of modern chronic kidney disease beyond chronic glomerulonephritis. The endoplasmic reticulum is one of the largest organelles, and endoplasmic reticulum stress (ERS) is the basic mechanism of metabolic disorder in all organs and tissues. Under the stimulation of stress-induced factors, the endoplasmic reticulum, as a trophic receptor, regulates adaptive and apoptotic ERS through molecular chaperones and three unfolded protein reaction (UPR) pathways, thereby regulating diabetic renal damage. Therefore, three pathway factors have different expressions in different sections of renal tissues. This study deeply discussed the specific reagents, animals, cells, and clinical models related to ERS in DKD, and reviewed ERS-related three pathways on DKD with glomerular filtration membrane, renal tubular reabsorption, and other pathological lesions of different renal tissues, as well as the molecular biological mechanisms related to the balance of adaption and apoptosis by searching and sorting out MeSH subject words from PubMed database.

Grape seed proanthocyanidin extract targets p66Shc to regulate mitochondrial biogenesis and dynamics in diabetic kidney disease

Mitochondrial biogenesis and dynamics are associated with renal mitochondrial dysfunction and the pathophysiological development of diabetic kidney disease (DKD). Decreased p66Shc expression prevents DKD progression by significantly regulating mitochondrial function. Grape seed proanthocyanidin extract (GSPE) is a potential therapeutic medicine for multiple kinds of diseases. The effect of GSPE on the mitochondrial function and p66Shc in DKD has not been elucidated. Hence, we decided to identify p66Shc as a therapeutic target candidate to probe whether GSPE has a renal protective effect in DKD and explored the underlying mechanisms.

METHODS

In vivo, rats were intraperitoneally injected with streptozotocin (STZ) and treated with GSPE. Biochemical changes, mitochondrial morphology, the ultrastructure of nephrons, and protein expression of mitochondrial biogenesis (SIRT1, PGC-1α, NRF1, TFAM) and dynamics (DRP1, MFN1) were determined. In vitro, HK-2 cells were transfected with p66Shc and treated with GSPE to evaluate changes in cell apoptosis, reactive oxygen species (ROS), mitochondrial quality, the protein expression.

RESULTS

In vivo, GSPE significantly improved the renal function of rats, with less proteinuria and a lower apoptosis rate in the injured renal tissue. Besides, GSPE treatment increased SIRT1, PGC-1α, NRF1, TFAM, and MFN1 expression, decreased p66Shc and DRP1 expression. In vitro, overexpression of p66Shc decreased the resistance of HK-2 cells to high glucose toxicity, as shown by increased apoptosis and ROS production, decreased mitochondrial quality and mitochondrial biogenesis, and disturbed mitochondrial dynamic homeostasis, ultimately leading to mitochondrial dysfunction. While GSPE treatment reduced p66Shc expression and reversed these changes.

CONCLUSION

GSPE can maintain the balance between mitochondrial biogenesis and dynamics by negatively regulating p66Shc expression.

Bioactive Compounds, Health Benefits and Food Applications of Grape

Grape (Vitis vinifera L.) is one of the most popular fruits worldwide. It contains various bioactive compounds, such as proanthocyanidins, anthocyanins, flavonols, phenolic acids and stilbenes, the contents of which could vary considerably in grape skin, pulp and seed. Many studies have revealed that grape possesses a variety of health benefits, such as antioxidant, anti-inflammatory, gut-microbiota-modulating, anticancer and cardioprotective effects. Grape is eaten as fresh fruit and is also used as raw material to produce various products, such as wine, grape juice and raisins. Moreover, the byproducts of grape, such as grape pomace and grape seed, have many applications in the food industry. In this paper, the bioactive compounds in grape are briefly summarized based on literature published in recent years. In addition, the health benefits of grape and its bioactive components are discussed, with special attention paid to the underlying mechanisms. Furthermore, the applications of grape in the food industry are elucidated, especially the applications of grape pomace and grape seed. This paper can contribute to understanding the health benefits and mechanisms of grape and its bioactive compounds, as well as the promotion of the use of grape in the food industry.

Oxidative Stress and NRF2/KEAP1/ARE Pathway in Diabetic Kidney Disease (DKD): New Perspectives

Diabetes mellitus (DM) is one of the most debilitating chronic diseases worldwide, with increased prevalence and incidence. In addition to its macrovascular damage, through its microvascular complications, such as Diabetic Kidney Disease (DKD), DM further compounds the quality of life of these patients. Considering DKD is the main cause of end-stage renal disease (ESRD) in developed countries, extensive research is currently investigating the matrix of DKD pathophysiology. Hyperglycemia, inflammation and oxidative stress (OS) are the main mechanisms behind this disease. By generating pro-inflammatory factors (e.g., IL-1,6,18, TNF-α, TGF-β, NF-κB, MCP-1, VCAM-1, ICAM-1) and the activation of diverse pathways (e.g., PKC, ROCK, AGE/RAGE, JAK-STAT), they promote a pro-oxidant state with impairment of the antioxidant system (NRF2/KEAP1/ARE pathway) and, finally, alterations in the renal filtration unit. Hitherto, a wide spectrum of pre-clinical and clinical studies shows the beneficial use of NRF2-inducing strategies, such as NRF2 activators (e.g., Bardoxolone methyl, Curcumin, Sulforaphane and their analogues), and other natural compounds with antioxidant properties in DKD treatment. However, limitations regarding the lack of larger clinical trials, solubility or delivery hamper their implementation for clinical use. Therefore, in this review, we will discuss DKD mechanisms, especially oxidative stress (OS) and NRF2/KEAP1/ARE involvement, while highlighting the potential of therapeutic approaches that target DKD via OS.

Molecular Mechanistic Pathways Targeted by Natural Antioxidants in the Prevention and Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) is the progressive loss of renal function and the leading cause of end-stage renal disease (ESRD). Despite optimal therapy, many patients progress to ESRD and require dialysis or transplantation. The pathogenesis of CKD involves inflammation, kidney fibrosis, and blunted renal cellular antioxidant capacity. In this review, we have focused on in vitro and in vivo experimental and clinical studies undertaken to investigate the mechanistic pathways by which these compounds exert their effects against the progression of CKD, particularly diabetic nephropathy and kidney fibrosis. The accumulated and collected data from preclinical and clinical studies revealed that these plants/bioactive compounds could activate autophagy, increase mitochondrial bioenergetics and prevent mitochondrial dysfunction, act as modulators of signaling pathways involved in inflammation, oxidative stress, and renal fibrosis. The main pathways targeted by these compounds include the canonical nuclear factor kappa B (NF-κB), canonical transforming growth factor-beta (TGF-β), autophagy, and Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid factor 2-related factor 2 (Nrf2)/antioxidant response element (ARE). This review presented an updated overview of the potential benefits of these antioxidants and new strategies to treat or reduce CKD progression, although the limitations related to the traditional formulation, lack of standardization, side effects, and safety.

Flavonoids on diabetic nephropathy: advances and therapeutic opportunities

With the advances in biomedical technologies, natural products have attracted substantial public attention in the area of drug discovery. Flavonoids are a class of active natural products with a wide range of pharmacological effects that are used for the treatment of several diseases, in particular chronic metabolic diseases. Diabetic nephropathy is a complication of diabetes with a particularly complicated pathological mechanism that affects at least 30% of diabetic patients and represents a great burden on public health. A large number of studies have shown that flavonoids can alleviate diabetic nephropathy. This review systematically summarizes the use of common flavonoids for the treatment of diabetic nephropathy. We found that flavonoids play a therapeutic role in diabetic nephropathy mainly by regulating oxidative stress and inflammation. Nrf-2/GSH, ROS production, HO-1, TGF-β1 and AGEs/RAGE are involved in the process of oxidative stress regulation. Quercetin, apigenin, baicalin, luteolin, hesperidin, genistein, proanthocyanidin and eriodictyol were found to be capable of alleviating oxidative stress related to the aforementioned factors. Regarding inflammatory responses, IL-1, IL-6β, TNF-α, SIRT1, NF-κB, and TGF-β1/smad are thought to be essential. Quercetin, kaempferol, myricetin, rutin, genistein, proanthocyanidin and eriodictyol were confirmed to influence the above targets. As a result, flavonoids promote podocyte autophagy and inhibit the overactivity of RAAS by suppressing the upstream oxidative stress and inflammatory pathways, ultimately alleviating DN. The above results indicate that flavonoids are promising drugs for the treatment of diabetic nephropathy. However, due to deficiencies in the effect of flavonoids on metabolic processes and their lack of structural stability in the body, further research is required to address these issues.

Entelon® (Vitis vinifera Seed Extract) Prevents Cancer Metastasis via the Downregulation of Interleukin-1 Alpha in Triple-Negative Breast Cancer Cells

Interleukin-1 (IL1) is a proinflammatory cytokine and promotes cancer cell proliferation and invasiveness in a diversity of cancers, such as breast and colon cancer. Here, we focused on the pharmacological effect of Entelon^® (ETL) on the tumorigenesis of triple-negative breast cancer (TNBC) cells by IL1-alpha (IL1A). IL1A enhanced the cell growth and invasiveness of TNBC cells. We observed that abnormal IL1A induction is related with the poor prognosis of TNBC patients. IL1A also increased a variety of chemokines such as CCL2 and IL8. Interestingly, IL1A expression was reduced by the ETL treatment. Here, we found that ETL significantly decreased the MEK/ERK signaling pathway in TNBC cells. IL1A expression was reduced by UO126. Lastly, we studied the effect of ETL on the metastatic potential of TNBC cells. Our results showed that ETL significantly reduced the lung metastasis of TNBC cells. Our results showed that IL1A expression was regulated by the MEK/ERK- and PI3K/AKT-dependent pathway. Taken together, ETL inhibited the MEK/ERK and PI3K/AKT signaling pathway and suppressing the lung metastasis of TNBC cells through downregulation of IL1A. Therefore, we propose the possibility of ETL as an effective adjuvant for treating TNBC.

NADH/NAD+ Redox Imbalance and Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a common and severe complication of diabetes mellitus. If left untreated, DKD can advance to end stage renal disease that requires either dialysis or kidney replacement. While numerous mechanisms underlie the pathogenesis of DKD, oxidative stress driven by NADH/NAD⁺ redox imbalance and mitochondrial dysfunction have been thought to be the major pathophysiological mechanism of DKD. In this review, the pathways that increase NADH generation and those that decrease NAD⁺ levels are overviewed. This is followed by discussion of the consequences of NADH/NAD⁺ redox imbalance including disruption of mitochondrial homeostasis and function. Approaches that can be applied to counteract DKD are then discussed, which include mitochondria-targeted antioxidants and mimetics of superoxide dismutase, caloric restriction, plant/herbal extracts or their isolated compounds. Finally, the review ends by pointing out that future studies are needed to dissect the role of each pathway involved in NADH-NAD⁺ metabolism so that novel strategies to restore NADH/NAD⁺ redox balance in the diabetic kidney could be designed to combat DKD.

Activation of Insulin Signaling by Botanical Products

Type 2 diabetes (T2D) is a worldwide health problem, ranked as one of the leading causes for severe morbidity and premature mortality in modern society. Management of blood glucose is of major importance in order to limit the severe outcomes of the disease. However, despite the impressive success in the development of new antidiabetic drugs, almost no progress has been achieved with regard to the development of novel insulin-sensitizing agents. As insulin resistance is the most eminent factor in the patho-etiology of T2D, it is not surprising that an alarming number of patients still fail to meet glycemic goals. Owing to its wealth of chemical structures, the plant kingdom is considered as an inventory of compounds exerting various bioactivities, which might be used as a basis for the development of novel medications for various pathologies. Antidiabetic activity is found in over 400 plant species, and is attributable to varying mechanisms of action. Nevertheless, relatively limited evidence exists regarding phytochemicals directly activating insulin signaling, which is the focus of this review. Here, we will list plants and phytochemicals that have been found to improve insulin sensitivity by activation of the insulin signaling cascade, and will describe the active constituents and their mechanism of action.

Grape seed proanthocyanidins attenuate apoptosis in ischemic stroke

Grape seed proanthocyanidins (GSP) has been reported to attenuate endoplasmic reticulum (ER) stress-induced apoptosis, which is associated with ischemic stroke. However, whether GSP pays crucial roles in ischemic stroke still remains unclear. The purpose of this study is to explore the role of GSP in ischemic stroke and the underlying mechanism. The ischemic stroke mouse model was established by middle cerebral artery occlusion. GSP administration was performed intragastrically. Long-term neurological outcome was assessed by the foot fault test after reperfusion. Brain injury was identified by infarct volume from 2,3,5-triphenyltetrazolium chloride staining. Neuronal apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling. The expression levels of Bax, Bcl-2, Cleaved Caspase-3, phosphorylated ERK (p-ERK), ERK, Glucose-regulated protein 78 kDa (GRP78), Caspase-12 were detected by western blotting. In mice with ischemia stroke, GSP administration improved long-term neurological outcomes by attenuating ischemia-reperfusion induced neuronal apoptosis and brain injury. Mechanically, GSP performance inhibited the expression levels of ER stress-associated genes. GSP protects mice against ischemic stroke via attenuating neuronal apoptosis. Moreover, GSP attenuated ER stress-associated apoptosis by inhibiting GRP78 and Caspase-12. Our study indicates that GSP attenuates neuronal apoptosis in ischemic stroke, which shows the potential for ischemic stroke treatment.

Grape Seed Proanthocyanidin Extract Ameliorates Cardiac Remodelling After Myocardial Infarction Through PI3K/AKT Pathway in Mice

Myocardial infarction is one of the most serious fatal diseases in the world, which is due to acute occlusion of coronary arteries. Grape seed proanthocyanidin extract (GSPE) is an active compound extracted from grape seeds that has anti-oxidative, anti-inflammatory and anti-tumor pharmacological effects. Natural products are cheap, easy to obtain, widely used and effective. It has been used to treat numerous diseases, such as cancer, brain injury and diabetes complications. However, there are limited studies on its role and associated mechanisms in myocardial infarction in mice. This study showed that GSPE treatment in mice significantly reduced cardiac dysfunction and improved the pathological changes due to MI injury. In vitro, GSPE inhibited the apoptosis of H9C2 cells after hypoxia culture, resulting in the expression of Bax decreased and the expression of Bcl-2 increased. The high expression of p-PI3K and p-AKT was detected in MI model in vivo and in vitro. The use of the specific PI3K/AKT pathway inhibitor LY294002 regressed the cardio-protection of GSPE. Our results showed that GSPE could improve the cardiac dysfunction and remodeling induced by MI and inhibit cardiomyocytes apoptosis in hypoxic conditions through the PI3K/AKT signaling pathway.

An Evaluation of Traditional Persian Medicine for the Management of SARS-CoV-2

A new coronavirus causing severe acute respiratory syndrome (SARS-CoV-2) has emerged and with it, a global investigation of new antiviral treatments and supportive care for organ failure due to this life-threatening viral infection. Traditional Persian Medicine (TPM) is one of the most ancient medical doctrines mostly known with the manuscripts of Avicenna and Rhazes. In this paper, we first introduce a series of medicinal plants that would potentially be beneficial in treating SARS-CoV-2 infection according to TPM textbooks. Then, we review medicinal plants based on the pharmacological studies obtained from electronic databases and discuss their mechanism of action in SARS-CoV-2 infection. There are several medicinal plants in TPM with cardiotonic, kidney tonic, and pulmonary tonic activities, protecting the lung, heart, and kidney, the three main vulnerable organs in SARS-CoV-2 infection. Some medicinal plants can prevent "humor infection", a situation described in TPM which has similar features to SARS-CoV-2 infection. Pharmacological evaluations are in line with the therapeutic activities of several plants mentioned in TPM, mostly through antiviral, cytoprotective, anti-inflammatory, antioxidant, and anti-apoptotic mechanisms. Amongst the primarily-introduced medicinal plants from TPM, rhubarb, licorice, garlic, saffron, galangal, and clove are the most studied plants and represent candidates for clinical studies. The antiviral compounds isolated from these plants provide novel molecular structures to design new semisynthetic antiviral agents. Future clinical studies in healthy volunteers as well as patients suffering from pulmonary infections are necessary to confirm the safety and efficacy of these plants as complementary and integrative interventions in SARS-CoV-2 infection.

Protective Effects of Grape Seed Proanthocyanidins on the Kidneys of Diabetic Rats through the Nrf2 Signalling Pathway

Background

Diabetic nephropathy (DN) is the most common cause of end-stage renal failure. Grape seed proanthocyanidin extract (GSPE) is a powerful antioxidant that is believed to protect the kidney through antioxidant action. However, the underlying mechanism of GSPE protection against DN remains unclear.

Objective

To explore if GSPE can improve DN by activating nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant response element signalling and to clarify its possible mechanism. Materials and methods. Ten healthy Sprague-Dawley rats were randomly selected as controls. Rats with streptozotocin-induced diabetes were randomly divided into three groups (10 animals/group): type 2 diabetes mellitus (T2DM) group (untreated), L-GSPE group (treated with 125-mg/kg/day GSPE for 8 weeks), and H-GSPE group (treated with 250 mg/kg/day GSPE for 8 weeks).

Results

Renal histopathological results indicated limited pathological damage in GSPE-treated groups. Compared with the T2DM group, the H-GSPE group had significantly reduced kidney weight and renal index. Similarly, the levels of fasting blood glucose, serum creatinine, blood urea nitrogen, uric acid, urinary albumin, and renal malondialdehyde (p < 0.05) were also significantly decreased. In addition, GSPE significantly increased the levels of superoxide dismutase, total antioxidative capability, and glutathione (p < 0.05) as well as the protein levels of Nrf2, HO-1, glutathione S-transferase, and NAD (P)H quinone oxidoreductase 1 (p < 0.05).

Conclusion

The results indicate that GSPE reduced renal damage in rats with diabetes by activating the Nrf2 signalling pathway, which consequently increased the antioxidant capacity of the tissue. Therefore, GSPE is a potential natural agent for the treatment of diabetic nephropathy.

Effects of Grape Seed Proanthocyanidin Extract on Obesity

Obesity is a chronic metabolic disease resulting from excessive fat accumulation and/or abnormal distribution caused by multiple factors. As a major component of metabolic syndrome, obesity is closely related to many diseases such as type 2 diabetes mellitus, hyperlipidemia, hypertension, coronary heart disease, stroke and cancer. Hence, the problem of obesity cannot be ignored, and recent studies have shown that grape seed proanthocyanidin extract (GSPE) has an antiobesity effect. This paper systematically reviews the research progress and potential mechanism of GSPE emphasizing on obesity prevention and treatment.