Nelumbo nucifera leaves extract attenuate the pathological progression of diabetic nephropathy in high-fat diet-fed and streptozotocin-induced diabetic rats

Optimizing Extraction, Evaluating Antioxidant Activity, and Analyzing Bioactive Compounds in Trikaysornmas Formula

The Trikaysornmas formula (TKM) represents a prevalent Thai traditional remedy utilized extensively in Thailand. Its traditional uses include appetite enhancement, functions as a nourishing tonic, and exhibits adaptogenic properties. Comprising Aegle marmelos fruit, Nelumbo nucifera stamen, and Jatropha multifida bark, this formula embodies the synergy among these three herbs. The objective of this study was to optimize the extraction method, determine the active compounds in the TKM, and evaluate its antioxidant activity. The optimization of the extraction method for this formula was studied using an experimental design. Phytochemical components such as total phenolics, total flavonoids, total carotenoids, and total alkaloids were assessed utilizing a colorimetric method. Antioxidant activities were assessed through DPPH free radical scavenging, ABTS radical cation decolorization, oxygen radical absorbance capacity, ferric reducing antioxidant power, metal chelating activity, and lipid peroxidation assay. For the analysis of active constituents in the formula, gallic acid, kaempferol-3-o-glucoside, imperatorin, vitexin, and scopoletin, a validated reversed-phase column high-performance liquid chromatography (HPLC) method was developed. The total active contents including phenolic, flavonoid, carotenoid, and alkaloid compounds were found in the formula. The developed HPLC method exhibited reliable results in all validation parameters. TKM demonstrated antioxidant activity in the models used in this research. The findings from this study can serve as valuable tools for standardization and quality control measures. Additionally, they can contribute to maximizing the possibilities inherent in this traditional Thai formulation.

Diabetic Kidney Disease: Contribution of Phenyl Sulfate Derived from Dietary Tyrosine upon Gut Microbiota Catabolism

Deranged gut microbiota can release increased levels of uremic toxins leading to exacerbated kidney injury. In diabetic kidney disease (DKD), phenyl sulfate (PS) derived from tyrosine catabolism by gut microbiota has been demonstrated to be both an early diagnostic marker and a therapeutic target. In this perspective article, we summarize PS generation pathways and recent findings on PS and kidney injury in DKD. Increasing evidence has shown that the underlying mechanisms of PS-induced kidney injury mainly involve oxidative stress, redox imbalance, and mitochondrial dysfunction, which all may be targeted to attenuate PS-induced kidney injury. For future research directions, we think that a deeper understanding of the pathogenic role of PS in kidney injury using a variety of diabetic animal models should be investigated. Moreover, we also suggest beneficial approaches that could be used to mitigate the deleterious effect of PS on the kidney. These approaches include caloric restriction, tyrosine restriction, and administration of ketogenic drugs, ketogenic diets or natural products; all of which should be conducted under obese and diabetic conditions.

Antidiabetic effect of combined extract of Coccinia grandis and Blumea balsamifera on streptozotocin-nicotinamide induced diabetic rats

BACKGROUND

Coccinia grandis and Blumea balsamifera are two medicinal plants that have been known to have good antidiabetic properties. Combining these two plant extracts may generate a greater effect that can increase efficacy and decrease the dose.

OBJECTIVE

This research investigated the antidiabetic activity of the combination of C. grandis and B. balsamifera leaves extracts on experimental diabetic rats.

MATERIALS AND METHODS

The dried leaves of C. grandis and B. balsamifera were powdered and macerated with ethanol 70% (v/v). A diabetic condition in male Wistar albino rats was generated by intraperitoneal injection of a single dose of streptozotocin (65 mg/kg) followed by nicotinamide (110 mg/kg). Diabetes-confirmed rats were then given glibenclamide (4.5 mg/kg), C. grandis extract (300 mg/kg), B. balsamifera extract (150 mg/kg), and the combined extracts with a dose ratio of 1:1, 1:3, and 3:1. The treatment was performed for 28 days and fasting blood glucose was tested once a week. The pancreas and liver organs were taken on day 29 for antioxidant, histological, and immunohistochemical assessment.

RESULTS

Among all the extracts, the combined extract with a ratio of 1:3 showed the greatest glucose lowering effect. This combination also lowered malondialdehyde levels while increasing superoxide dismutase and catalase levels in the pancreas and liver organs. Histological examination showed this combination regenerated the islet of Langerhans. It also increased pancreatic insulin expression in immunohistochemical evaluation.

CONCLUSION

This study revealed that the combined extracts of C. grandis and B. balsamifera exhibited enhanced antidiabetic activity via ameliorating oxidative stress, regenerating β-cells, and increasing insulin expression.

Nelumbo nucifera leaves extract ameliorated scopolamine-induced cognition impairment via enhanced adult hippocampus neurogenesis

In this presentation, we explored the molecular mechanisms of N. nucifera leaf water extracts (NLWEs) and polyphenol extract (NLPE) on scopolamine-induced cell apoptosis and cognition defects. The administration of NLWE and NLPE did not alter the body weight and serum biomarker rs and significantly ameliorated scopolamine-induced cognition impairment according to Y-maze test analysis. In mice, treatment with scopolamine disrupted normal histoarchitecture in the hippocampus, whereas the administration of NLWE and NLPE reversed the phenomenon. Western blot analysis revealed that scopolamine mitigated the expression of doublecortin (DCX), nestin, and NeuN, and cotreatment with NLWE or NLPE significantly recovered the expression of these proteins. NLWE and NLPE upregulated DCX and NeuN expression in the hippocampus region, as evidenced by immunohistochemical staining analysis of scopolamine-treated mice. NLWE and NLPE obviously elevated brain-derived neurotrophic factor (BDNF) and enhanced its downstream proteins activity. NLWE and NLPE attenuated scopolamine-induced apoptosis by reducing Bax and increased Bcl-2 expression. In addition, scopolamine also triggered apoptosis in human neuroblastoma SH-SY5Y cells whereas co-treatment with NLWE or quercetin-3-glucuronide (Q3G) reversed the phenomenon. NLWE or Q3G enhanced Bcl-2 and reduced Bax expression in the presence of scopolamine in SH-SY5Y cells. NLWE or Q3G recovered the inhibitory effects of scopolamine on neurogenesis and BDNF signals in SH-SY5Y cells. Overall, our results revealed that N. nucifera leaf extracts and Q3G promoted adult hippocampus neurogenesis and prevented apoptosis to mitigate scopolamine-induced cognition dysfunction through the regulation of BDNF signaling pathway.

Maca roots: A potential therapeutic in the management of metabolic disorders through the modulation of metabolic biochemical markers in rats fed high-fat high-carbohydrate diet

ETHNOPHARMACOLOGICAL RELEVANCE

Maca root (Lepidium meyenii Walp.) is a Peruvian plant of the Brassicaceae family. Maca roots are popular food supplements used to treat a variety of ailments described traditionally as enhancing metabolic and health conditions.

AIM OF THE STUDY

Metabolic syndrome (MetS) has been the real scourge globally, affecting more than one-fourth of the global population. MetS causes the development of multi-organ illnesses, including altered blood cholesterol and sugar levels, oxidative stress, and hypertension. This study evaluated maca root total methanolic extract (MTE) as a potential nutraceutical to manage the complications of MetS.

MATERIALS AND METHODS

After the first 4 weeks of a high-fat high-carbohydrate diet (HFCD), streptozotocin (STZ) was injected in Wistar rats to induce the MetS model. Animals were treated orally with MTE at 100 mg/kg and 300 mg/kg for 4 weeks compared to metformin at 200 mg/kg after confirmation of diabetes.

RESULTS

One month of MTE supplementation in HFCD-fed rats remarkably decreased the elevation of blood glucose and lipids, improved liver function and insulin resistance, additionally it successfully restored the state of inflammatory and oxidative stress. The extract was standardized to contain total phenolics equal to 24.45 ± 0.96 μg Gallic acid/mg extract.

CONCLUSIONS

Our findings suggest that MTE improves MetS by reducing hyperglycemia, hyperlipidemia, inflammation, and oxidative stress. While also improving beta cell secretory functions, implying that MTE could be used as a balancing drug in the prevention and treatment of metabolic abnormalities linked to type 2 diabetes.

Assessment of multi-biomedical efficiency of Andrographis paniculata shoot extracts through in-vitro analysis and major compound identification

The present investigation looked into the various biomedical potentials of Andrographis paniculata shoot extracts. The results showed that the methanol extract (Met-E) of A. paniculata contains more phytochemicals than the acetone and petroleum ether extracts, including alkaloids, saponins, tannins, phenolics, flavonoids, glycosides, terpenoids, phytosterol, steroids, and protein. Accordingly, the Met-E alone showed considerable bactericidal activity (through agar well diffusion method) against the bacterial pathogens namely Shigella dysenteriae, Bacillus cereus, Salmonella typhi, Enterococcus faecalis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphlococcus aureus, E. coli, and B. subtilis. This bactericidal activity was found as dose dependent manner, since at 1000 μg ml concentration, the Met-E showed better antibacterial activity. Similarly, at increased concentration (1000 μg ml) it showed notable antidiabetic (α-amylase inhibition: 74.31% and α-glucosidase inhibition: 72.34%), antioxidant (DPPH: 78.24%), and anti-inflammatory (albumin denaturation inhibition: 79.84% and lipoxigenase inhibition: 69.4%) activities. The phytochemical profiling of Met-E was characterized by UV-visible spectrophotometer (UV-vis), Gas Chromatography-Mass Spectrometry (GC/MS), Fourier transform infrared (FTIR), and High Performance Liquid Chromatography (HPLC) analyses. The results showed the Met-E contain bioactive compounds such as gallic acid, epicatechin, catechin, naringin, vitexin-2-rhamnoside, taxifolin, kaempferol, hesperidin, myricetin, rutin, quercetin, phloretin, and ursolic acid compounds. While most of these substances have been recognised for their pharmacological application perspective, the biological properties of particular substances must be studied in the future using in-vivo strategies.

Chiranthodendron pentadactylon Larreat (Sterculiaceae), a Potential Nephroprotector against Oxidative Damage Provoked by STZ-Induced Hyperglycemia in Rats

BACKGROUND

Chiranthodendron pentadactylon, known in Mexico as the "tree of the little hands", flower's infusion is used to treat kidney failure associated with diseases such as diabetes. The aim of this work is to evaluate the antioxidant effect of the methanolic extract of its flowers on oxidative damage in kidneys caused by streptozotocin in rats.

METHODS

The extract phytochemical profile was performed with HPLC. Antioxidant potential in vitro was determined with DPPH and total phenolic tests; antioxidant evaluation in vivo was performed in diabetic rats administered daily via the intragastric route (100 and 200 mg/kg) for 6 weeks; serum glucose/creatinine, food/water consumption, and urinary volume were measured. Relative weight, protein/DNA ratios and oxidative stress were measured in renal tissue.

RESULTS

The extract showed 20.53% of total phenolic content and IC50 of 18.05 µg/mL in DPPH, and this was associated with ferulic acid, phloretin and α-amyrin. Both doses showed a moderate decrease in the protein/DNA ratio in renal tissue, and the same behavior was observed for total urinary protein loss and serum creatinine, while the best antioxidant effect was exerted by a lower dose, which increased catalase activity and decreased lipid peroxidation in the kidneys.

CONCLUSIONS

Results demonstrated that C. pentadactylon methanolic flower's extract improves renal function through antioxidant mechanisms during experimental diabetes.

Mulberry leaf extract and neochlorogenic acid ameliorate glucolipotoxicity-induced diabetic nephropathy in high-fat diet-fed db/db mice

Diabetic nephropathy, a major diabetes complication, is often exacerbated by glucolipotoxicity. The potential benefits of mulberry leaf extract (MLE) and its primary component, neochlorogenic acid (nCGA), in combating this condition have not been extensively explored. High-fat diet-fed db/db mice were employed as a model for glucolipotoxicity-induced diabetic nephropathy. The mice were treated with MLE or nCGA, and their body weight, insulin sensitivity, blood lipid profiles, and kidney function were assessed. In addition, modulation of the JAK-STAT, pAKT, Ras, and NF-κB signaling pathways by MLE and nCGA was evaluated. MLE and nCGA did not significantly decrease blood glucose level but effectively mitigated the adverse effects of a high-fat diet on blood lipid profile and kidney function. Improvements in body weight, insulin sensitivity, and kidney structure, along with a reduction in fibrosis, were observed. Both MLE and nCGA regulated lipid metabolism abnormalities, significantly inhibited the accumulation of glycosylated substances in glomeruli, and modulated crucial signaling pathways involved in diabetic nephropathy. Although they do not directly affect blood glucose level, MLE and nCGA show significant potential in managing glucolipotoxicity-induced diabetic nephropathy by targeting lipid metabolism and key molecular pathways. The present findings suggest MLE and nCGA may be promising therapeutic agents for diabetic nephropathy, and further exploration in human patients is warranted.

Optimizing diabetic kidney disease animal models: Insights from a meta-analytic approach

Diabetic kidney disease (DKD) is a prevalent complication of diabetes, often leading to end-stage renal disease. Animal models have been widely used to study the pathogenesis of DKD and evaluate potential therapies. However, current animal models often fail to fully capture the pathological characteristics of renal injury observed in clinical patients with DKD. Additionally, modeling DKD is often a time-consuming, costly, and labor-intensive process. The current review aims to summarize modeling strategies in the establishment of DKD animal models by utilizing meta-analysis related methods and to aid in the optimization of these models for future research. A total of 1215 articles were retrieved with the keywords of "diabetic kidney disease" and "animal experiment" in the past 10 years. Following screening, 84 articles were selected for inclusion in the meta-analysis. Review manager 5.4.1 was employed to analyze the changes in blood glucose, glycosylated hemoglobin, total cholesterol, triglyceride, serum creatinine, blood urea nitrogen, and urinary albumin excretion rate in each model. Renal lesions shown in different models that were not suitable to be included in the meta-analysis were also extensively discussed. The above analysis suggested that combining various stimuli or introducing additional renal injuries to current models would be a promising avenue to overcome existing challenges and limitations. In conclusion, our review article provides an in-depth analysis of the limitations in current DKD animal models and proposes strategies for improving the accuracy and reliability of these models that will inspire future research efforts in the DKD research field.

Diabetic Nephropathy: Significance of Determining Oxidative Stress and Opportunities for Antioxidant Therapies

Diabetes mellitus (DM) belongs to the category of socially significant diseases with epidemic rates of increases in prevalence. Diabetic nephropathy (DN) is a specific kind of kidney damage that occurs in 40% of patients with DM and is considered a serious complication of DM. Most modern methods for treatments aimed at slowing down the progression of DN have side effects and do not produce unambiguous positive results in the long term. This fact has encouraged researchers to search for additional or alternative treatment methods. Hyperglycemia has a negative effect on renal structures due to a number of factors, including the activation of the polyol and hexosamine glucose metabolism pathways, the activation of the renin-angiotensin-aldosterone and sympathetic nervous systems, the accumulation of advanced glycation end products and increases in the insulin resistance and endothelial dysfunction of tissues. The above mechanisms cause the development of oxidative stress (OS) reactions and mitochondrial dysfunction, which in turn contribute to the development and progression of DN. Modern antioxidant therapies for DN involve various phytochemicals (food antioxidants, resveratrol, curcumin, alpha-lipoic acid preparations, etc.), which are widely used not only for the treatment of diabetes but also other systemic diseases. It has also been suggested that therapeutic approaches that target the source of reactive oxygen species in DN may have certain advantages in terms of nephroprotection from OS. This review describes the significance of studies on OS biomarkers in the pathogenesis of DN and analyzes various approaches to reducing the intensity of OS in the prevention and treatment of DN.

Translation Animal Models of Diabetic Kidney Disease: Biochemical and Histological Phenotypes, Advantages and Limitations

Animal models play a crucial role in studying the pathogenesis of diseases, developing new drugs, identifying disease risk markers, and improving means of prevention and treatment. However, modeling diabetic kidney disease (DKD) has posed a challenge for scientists. Although numerous models have been successfully developed, none of them can encompass all the key characteristics of human DKD. It is essential to choose the appropriate model according to the research needs, as different models develop different phenotypes and have their limitations. This paper provides a comprehensive overview of biochemical and histological phenotypes, modeling mechanisms, advantages and limitations of DKD animal models, in order to update relevant model information and provide insights and references for generating or selecting the appropriate animal models to fit different experimental needs.

A Review of Medicinal Plants with Renoprotective Activity in Diabetic Nephropathy Animal Models

Diabetic nephropathy (DN), also recognized as diabetic kidney disease, is a kidney malfunction caused by diabetes mellitus. A possible contributing factor to the onset of DN is hyperglycemia. Poorly regulated hyperglycemia can damage blood vessel clusters in the kidneys, leading to kidney damage. Its treatment is difficult and expensive because its causes are extremely complex and poorly understood. Extracts from medicinal plants can be an alternative treatment for DN. The bioactive content in medicinal plants inhibits the progression of DN. This work explores the renoprotective activity and possible mechanisms of various medicinal plant extracts administered to diabetic animal models. Research articles published from 2011 to 2022 were gathered from several databases including PubMed, Scopus, ProQuest, and ScienceDirect to ensure up-to-date findings. Results showed that medicinal plant extracts ameliorated the progression of DN via the reduction in oxidative stress and suppression of inflammation, advanced glycation end-product formation, cell apoptosis, and tissue injury-related protein expression.

Extraction, purification, structural characteristics, biological activities, and application of the polysaccharides from Nelumbo nucifera Gaertn. (lotus): A review

Nelumbo nucifera Gaertn. (lotus) is a widely distributed plant with a long history of cultivation and consumption. Almost all parts of the lotus can be used as foodstuff and nourishment, or as an herb. It is noteworthy that the polysaccharides obtained from lotus exhibit surprisingly and satisfying biological activities, which explains the various benefits of lotus to human health, including anti-diabetes, anti-osteoporosis, antioxidant, anti-inflammatory, anti-tumor, etc. Here, we systematically review the recent major studies on extraction and purification methods of polysaccharides from different parts (rhizome, seed, leaf, plumule, receptacle and stamen) of lotus, as well as the characterization of their chemical structure, biological activity and structure-activity relationship, and the applications of lotus polysaccharides in different fields. This article will give an updated and deeper understanding of lotus polysaccharides and provide theoretical basis for their further research and application in human health and manufacture development.

The Nephroprotective Effects of Hibiscus sabdariffa Leaf and Ellagic Acid in Vitro and in Vivo Models of Hyperuricemic Nephropathy

Hyperuricemic nephropathy (HN) is caused by urate crystals that get deposited in the kidney and contribute to renal fibrosis. Uric acid (UA) has been proven to directly cause renal mesangial cell oxidative stress and fibrosis in the pathogenesis of HN. Some antioxidants can be used as chemopreventive agents of HN. Hibiscus sabdariffa leaf extracts (HLE), rich in polyphenol, have been shown to possess hypoglycemic, antioxidant, hypolipidemic, antiatherosclerotic, and anticancer effects. The aim of the study is to examine the inhibitory effect of HLE and its main component ellagic acid (EA) on renal fibrosis. In vitro, mouse renal glomerular mesangial SV40MES13 cells pretreated with UA were demonstrated to trigger obvious morphological changes and viability loss, as well as affect matrix metalloproteinases (MMPs) activities. Noncytotoxic doses of HLE and EA abolished the UA-induced cell injury and MMP-2/9 secretion. In addition, HLE and EA exhibited antioxidant and anti-inflammatory effects on the UA-treated cells with a reduction in transforming growth factor-beta (TGF-β) production. Next, the UA-activated pro-fibrotic factors, extracellular matrix (ECM) deposition, and epithelial-mesenchymal-transition (EMT) were inhibited by HLE or EA. Mechanistic assays indicated that antifibrotic effects of HLE might be mediated via TGF-β/Smad signaling, as confirmed by the transfection of Smad7 siRNA. In vivo, HLE and EA supplementations significantly alleviated HN development, which may result from inhibiting adenine-induced TGF-β production accompanying oxidative stress and inflammation, as well as fibrogenesis. Our data imply that EA-enriched HLE regulates the TGF-β/Smad signaling, which in turn led to reduced renal mesangial cell injury and fibrosis in HN and provided a new mechanism for its nephroprotective activity.

Acarbose Protects Glucolipotoxicity-Induced Diabetic Nephropathy by Inhibiting Ras Expression in High-Fat Diet-Fed db/db Mice

Diabetic nephropathy (DN) exacerbates renal tissue damage and is a major cause of end-stage renal disease. Reactive oxygen species play a vital role in hyperglycemia-induced renal injury. This study examined whether the oral hypoglycemic drug acarbose (Ab) could attenuate the progression of DN in type 2 diabetes mellitus mice. In this study, 50 mg/kg body weight of Ab was administered to high-fat diet (HFD)-fed db/db mice. Their body weight was recorded every week, and the serum glucose concentration was monitored every 2 weeks. Following their euthanasia, the kidneys of mice were analyzed through hematoxylin and eosin, periodic acid Schiff, Masson's trichrome, and immunohistochemistry (IHC) staining. The results revealed that Ab stabilized the plasma glucose and indirectly improved the insulin sensitivity and renal functional biomarkers in diabetic mice. In addition, diabetes-induced glomerular hypertrophy, the saccharide accumulation, and formation of collagen fiber were reduced in diabetic mice receiving Ab. Although the dosages of Ab cannot decrease the blood sugar in db/db mice, our results indicate that Ab alleviates glucolipotoxicity-induced DN by inhibiting kidney fibrosis-related proteins through the Ras/ERK pathway.

On demand regulation of blood glucose level by biocompatible oxidized starch-Con A nanogels for glucose-responsive release of exenatide

Diabetes mellitus is a long-term chronic disease characterized by abnormal high level blood glucose (BG). An artificial closed-loop system that mimics pancreatic β-cells and releases insulin on demand has potential to improve the therapeutic efficiency of diabetes. Herein, a lectin Concanavalin A modified oxidized starch nanogel was designed to regulate glucose dynamically according to different glucose concentrations. The nanogels were formed by double cross-linking the Concanavalin A and glucose units on oxidized starch via specific binding and amide bonds to achieve the high drug loading and glucose responsiveness. The results showed that oxidized starch nanogels prolonged the half-life of antidiabetic peptide drug exenatide and released it in response to high BG concentrations. It could absorb BG at a high level and maintain glucose homeostasis. Besides, the oxidized starch nanogels performed well in recovering regular BG level from hyperglycemia state and maintaining in euglycemia state that fitted in a biological rhythm. In addition, the nanogels showed high biocompatibility in vivo and could improve plasma half-life and therapeutic efficacy of exenatide. Overall, the nanogels protected peptide drugs from degradation in plasma as a glucose-responsive platform showing a high potential for peptide drugs delivery and antidiabetic therapy.

Identification of Antidiabetic Compounds from the Aqueous Extract of Sclerocarya birrea Leaves

Diabetes, a prevalent metabolic condition with a wide range of complications, is fast becoming a global health crisis. Herbal medicine and enhanced extracts are some of the therapeutic options used in the management of diabetes mellitus. The plant-derived molecules and their suitable structure modification have given many leads or drugs to the world such as metformin used as an antidiabetic drug. The stem extract of Sclerocarya birrea has been reported as a potent antidiabetic (glucose uptake) agent. However, the bioactive compounds have not been reported from S. birrea for treatment of diabetes. In this study, the spray-dried aqueous leaf extracts of S. birrea were investigated as an antidiabetic agent using a 2-deoxy-glucose (2DG) technique showing good stimulatory effect on glucose uptake in differentiated C2C12 myocytes with % 2DG uptake ranging from 110-180% that was comparable to the positive control insulin. Three compounds were isolated and identified using bioassay-guided fractionation of the spray-dried aqueous extract of S. birrea leaves: myricetin (1), myricetin-3-O-β-D-glucuronide (2) and quercetin-3-O-β-D-glucuronide (3). Their chemical structures were determined using NMR and mass spectrometric analyses, as well as a comparison of experimentally obtained data to those reported in the literature. The isolated compounds (1-3) were studied for their stimulatory actions on glucose uptake in differentiated C2C12 myocytes. The three compounds (1, 2 and 3) showed stimulatory effects on the uptake of 2DG in C2C12 myocytes with % 2DG uptake ranging from 43.9-109.1% that was better compared to the positive control insulin. Additionally, this is the first report of the flavonoid glycosides (myricetin-3-O-β-D-glucuronide) for antidiabetic activity and they are the main bioactive compound in the extract responsible for the antidiabetic activity. This result suggests that the S. birrea leaves have the potential to be developed for treatment of diabetes.

The Role of NF-κB and Bax/Bcl-2/Caspase-3 Signaling Pathways in the Protective Effects of Sacubitril/Valsartan (Entresto) against HFD/STZ-Induced Diabetic Kidney Disease

LCZ696 (valsartan/sacubitril) has the potential to slow the progression of diabetic kidney disease (DKD) according to previous reports. However, the renoprotective mechanism underlying LCZ696 remains unknown. This study aimed to investigate the therapeutic potential and underlying mechanism of LCZ696 in DKD in a type 2 diabetic (T2D) rat model. This model was established in this experiment by feeding a high-fat diet (HFD) for six weeks with a single dose of streptozotocin (STZ, 30 mg/kg body weight). Valsartan or LCZ696 was orally administered to T2D animals for eight weeks. HFD/STZ rats showed hyperglycemia, impaired insulin secretion, significant increases in urea, creatinine, cytokines, nuclear factor kappa B (NF-κB), oxidative stress, caspase-3 activity, glomerular and tubular damage, glomerulsclerosis, Bax and caspese-3 expressions along with a significant decline in IL-10, antioxidant markers, and Bcl-2 expression. The administration of LCZ696 to diabetic rats reduced the serum concentrations of glucose, urea, and creatinine. In addition, ELISA results demonstrated that diabetic rats treated with LCZ696 exhibited a reduction in inflammatory (IL-1β, TNF-α, IL-6) and an increase in anti-inflammatory (IL-10) cytokine levels. In addition, a notable decrease in NF-κB and caspase-3 activity was observed. At the level of renal tissue homogenate, diabetic animals treated with LCZ696 demonstrated clear restorations in GSH content and other antioxidant enzyme levels, in addition to a significant decrease in TBARS levels. In addition, LCZ696 inhibited the expression of the Bax and cleaved caspase-3 proteins and enhanced the expression of the Bcl-2 protein. Improvements in histopathological changes in kidney tissues confirmed and significantly supported these biochemical findings. In summary, LCZ696 alleviated DKD with possible mechanisms including inhibition of inflammation and apoptosis.

Jiangtang Sanhao formula ameliorates skeletal muscle insulin resistance via regulating GLUT4 translocation in diabetic mice

Jiangtang Sanhao formula (JTSHF), one of the prescriptions for treating the patients with diabetes mellitus (DM) in traditional Chinese medicine clinic, has been demonstrated to effectively ameliorate the clinical symptoms of diabetic patients with overweight or hyperlipidemia. The preliminary studies demonstrated that JTSHF may enhance insulin sensitivity and improve glycolipid metabolism in obese mice. However, the action mechanism of JTSHF on skeletal muscles in diabetic mice remains unclear. To this end, high-fat diet (HFD) and streptozotocin (STZ)-induced diabetic mice were subjected to JTSHF intervention. The results revealed that JTSHF granules could reduce food and water intake, decrease body fat mass, and improve glucose tolerance, lipid metabolism, and insulin sensitivity in the skeletal muscles of diabetic mice. These effects may be linked to the stimulation of GLUT4 expression and translocation via regulating AMPKα/SIRT1/PGC-1α signaling pathway. The results may offer a novel explanation of JTSHF to prevent against diabetes and IR-related metabolic diseases.

Terminalia catappa aqueous leaf extract reverses insulin resistance, improves glucose transport and activates PI3K/AKT signalling in high fat/streptozotocin-induced diabetic rats

Rising prevalence of type 2 diabetes mellitus (T2DM) in sub-Saharan Africa has necessitated surveys of antidiabetic medicinal plants. This study assessed the antidiabetic mechanism of Terminalia catappa aqueous leaf extract (TCA) in high fat/low dose streptozotocin-induced type 2 diabetic rats. T2DM was induced by a combination of high-fat diet and low dose STZ (30 mg/kg bw) and the animals were administered with TCA (400 and 800 mg/kg bw) orally daily for 28 days. Biochemical parameters and indices for diabetes including renal function tests and pancreatic histology were evaluated. Relative expression of hepatic insulin resistance, signalling and glucose transport genes were also assessed. Induction of T2DM resulted in significant (p < 0.05) weight loss, dysregulated glucose level and clearance, electrolyte imbalance and disrupted diabetic biochemical parameters. Diabetes onset also perturbed β-cell function and insulin resistance indices, damaged pancreas microanatomy, while disrupting the expression of insulin receptor substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT) and glucose transporter isoform 4 (GLUT-4) mRNA. Oral treatment of diabetic animals with TCA significantly (p < 0.05) ameliorated alterations due to T2DM induction in a manner comparable with glibenclamide. These results suggest TCA exerts its antidiabetic action by reversing insulin resistance, improving glucose transport and activating PI3K/AKT signalling.

Comparative Analysis of the Antioxidant and Antidiabetic Potential of Nelumbo nucifera Gaertn. and Nymphaea lotus L. var. pubescens (Willd.)

Background. Nelumbo nucifera Gaertn. and Nymphaea lotus L. var. pubescens (Willd.) are both aquatic rhizomatous perennial plants mostly found in the tropical region of Nepal, India, Bangladesh, China, and Eastern Asia. Nymphaea pubescens and Nelumbo nucifera plants are famous for their different biological activities such as antidiabetic, antioxidant, hepatoprotective, antidiarrheal, and anti-inflammatory properties. Objective. The present study majorly focused on the determination of in vitro antioxidant and antidiabetic properties of Nelumbo nucifera and Nymphaea pubescens. Methods. In vitro α-glucosidase inhibition was performed using PNPG as a substrate. Antioxidant property of the plant extract was determined by DPPH free radical scavenging assay. The aluminium trichloride method was done for the estimation of total flavonoid content. Likewise, Folin–Ciocalteu reagent was used for determining total phenolic content. Results. The total phenolic content of N. nucifera and N. pubescens was found to be 172.827 ± 0.41 and 194.87 ± 0.93 mg GAE/g, respectively, while the total flavonoid content was reported 17.12 ± 1.04 and 34.59 ± 1.73 mg QE/g, respectively. The IC50 values of the crude extract and its fractions of N. nucifera against the DPPH free radical ranged from 33.46 ± 0.6 to 3.52 ± 0.09 μg/mL, while that of the N. pubescens ranged from 14.30 ± 0.43 to 1.43 ± 0.08 μg/mL. Similarly, for the in vitro α-glucosidase inhibition activity, the IC50 of the crude extract and its fractions of N. nucifera varied from 349.86 ± 2.91 to 29.06 ± 0.24 μg/mL and that of N. pubescens ranged from 224.4 ± 6.85 to 5.29 ± 0.39 μg/mL. Conclusion. Both aquatic plants N. nucifera and N. pubescens show antioxidant properties and can inhibit α-glucosidase in in vitro. Further research is required to identify the inhibiting compounds.

Lotus essential oil improves neurite elongation and facilitates functional recovery after peripheral nerve injury

Injury to the peripheral nerve may lead to deficits in nerve function. An increase in the levels of free radicals plays a role in inhibition of nerve regeneration following damage. The aim of this study was to investigate the effects of lotus essential oil (LEO) on neurite outgrowth in vitro and nerve regeneration in vivo in a rat model of sciatic nerve crush injury. Gas chromatography-mass spectrometry analysis showed that the principal constituent of LEO was palmitic acid ethyl ester (25.12%). The radical scavenging activity of LEO was evaluated using the DPPH method, and was determined to be IC₅₀=29.01±2.93 µg/ml. LEO-treated sensory neurons exhibited increased neurite outgrowth and upregulated levels of phospho-ERK. Sensory and motor functions were improved in rats treated with 50 and 100 mg/kg LEO, and this was accompanied by an increase in the number of neurons in the dorsal root ganglia, as well as an increase in the nerve axon diameters following nerve injury. Taken together, these results suggests that LEO may serve as a novel pharmacological option for the management of peripheral nerve injury.

Network pharmacology-based identification of miRNA expression of Astragalus membranaceus in the treatment of diabetic nephropathy

Diabetic nephropathy (DN) is a common microvascular complication of diabetic patients, along with hypertension, hyperlipemia, proteinuria, edema, and other clinical manifestations. Astragalus membranaceus (AM) is a traditional Chinese medicine and has shown significant clinical efficacy against DN. However, the overall molecular mechanism of this therapeutic effect has not been entirely elucidated. Using network pharmacology, we aimed to identify the key active ingredients and potential pharmacological mechanisms of AM in treating DN and provide scientific evidence of its clinical efficacy.The active ingredients of AM were obtained from the traditional Chinese medicine systems pharmacology database, and the potential targets of AM were identified using the therapeutic target database. DN-related target genes were acquired from the Gene Expression Omnibus microarray dataset GSE1009 and 3 widely used databases-DisGeNET, GeneCards, and Comparative Toxicogenomics Database. The DN-AM common target protein interaction network was established by using the STRING database. Active ingredients candidate targets proteins networks were constructed using Cytoscape software for visualization. Additionally, gene ontology (GO) and Kyoto encyclopedia of genes and genomes pathway analyses were performed using the Database for Annotation, Visualization, and Integrated Discovery database. Target-regulating microRNAs (miRNAs) of these hub genes were obtained from the therapeutic target database, which could then be used for further identification of AM-regulated key miRNAs.A total of 17 active ingredients and 214 target proteins were screened from AM. 61 candidate co-expressed genes with therapeutic effects against DN were obtained and considered as potential therapeutic targets. GO and Kyoto encyclopedia of genes and genomes enrichment analysis showed that these genes were mainly involved in inflammatory response, angiogenesis, oxidative stress reaction, HIF signaling pathway, tumor necrosis factor signaling pathway, and VEGF signaling pathway. In all, 636 differentially expressed genes were identified between the DN patients and control group by using microarray data, GSE1009. Lastly, VEGFA, epidermal growth factor receptor, STAT1, and GJA1 were screened as hub genes. The relationships between miRNAs and hub genes were constructed, which showed that miR-302-3p, miR-372-3p, miR-373-3p, and miR-520-3p were regulated by VEGFA and epidermal growth factor receptor. Meanwhile, VEGFA also influenced miR-15-5p, miR-16-5p, miR-17-5p, miR-20-5p, miR-93-5p, miR-106-5p, miR-195-5p, miR-424-5p, miR-497-5p, and miR-519-3p. In addition, miR-1-3p and miR-206 were regulated by VEGFA and GJA1, and miR-23-3p was regulated by STAT1 and GJA1.To our knowledge, this study revealed for the first time the characteristic multiple components, multiple targets, and multiple pathways of AM that seem to be the underlying mechanisms of action of AM in the treatment of DN with respect to miRNAs.Private information from individuals will not be published. This systematic review also does not involve endangering participant rights. Ethical approval will not be required. The results may be published in a peer-reviewed journal or disseminated at relevant conferences.

The Protective Effect of Ethyl Acetate and n-Butanol Fractions of Wine-Steamed Ligustri Lucidi Fructus on Diabetic Nephropathy in Rats

Ligustri Lucidi Fructus (LLF), the dry and ripe fruit of Ligustrum lucidum W. T. Aiton (Oleaceae), is a traditional Chinese medicine for nourishing the liver and kidney in clinics for thousands of years. Wine-steamed Ligustri Lucidi Fructus (WLL) can alleviate coolness and smoothness of LLF and enhance the function of nourishing the liver and kidney, so ancient and modern medicine usually used it in clinics. First of all, we prepared the extracts of different polar fractions of WLL to explore the effective fractions and potential mechanisms of WLL in the treatment of diabetic nephropathy (DN). Then, HPLC method was used to determine the contents of 12 active components in WLL and its different polar components. Finally, the potential relationship between 12 active components and physicochemical parameters of DN rats was explored. The pharmacological experiments showed that WLL, ethyl acetate (EtOAc), and n-butanol (n-BuOH) extracts not only significantly alleviated the clinical symptoms and kidney damage of DN rats but also had obvious anti-inflammatory and antioxidant effects. In addition, the results of HPLC analysis showed that the 12 active components of WLL mainly existed in the extracts of EtOAc and n-BuOH. The Pearson correlation analysis showed 12 active components and physicochemical parameters had different degrees of correlation. In conclusion, we proved that the extracts of EtOAc and n-BuOH were the effective fractions of WLL in treating DN in rats, and they could regulate the levels of inflammatory cytokines and decrease oxidation stress, which provides a basis for further research on the mechanism of WLL in treating DN and provides a pharmacological and chemical foundation for the development of new anti-DN drugs.

Effect of genipin-1-β-d-gentiobioside on diabetic nephropathy in mice by activating AMP-activated protein kinase/silencing information regulator-related enzyme 1/ nuclear factor-κB pathway

OBJECTIVES

Genipin-1-β-d-gentiobioside (GG) is a kind of compound extracted from Gardenia jasminoides Ellis. The chemical structure of GG is similar to that of geniposide and has antidiabetic effects. We aimed to investigate the efficacy of GG on diabetic nephropathy (DN) in vivo and in vitro experiments and explore its potential mechanism.

METHODS

For high-fat diet/streptozotocin-induced DN mice used in our study, the general features of mice were analysed after GG treatment. Oxidative stress parameters and inflammatory factors were also measured by commercial kits. Kidney damage was assessed using hematoxylin and eosin (H&E), periodic acid-Schiff (PAS) and Masson staining, respectively. In vitro, podocyte injury was assessed by TUNEL and flow cytometric analyses. AMP-activated protein kinase/silencing information regulator related enzyme 1 (AMPK/SIRT1)/nuclear factor-κB (NF-κB) pathway-related proteins were detected by AMPK-siRNA intervention and western blotting.

KEY FINDINGS

Treatment of GG could increase cell survival and attenuated kidney damage. Despite the presence of inflammatory and oxidative stress, when GG retained the expression of AMPK/SIRT1, it could be observed that the downstream NLRP3 inflammatory-related proteins were inhibited.

CONCLUSIONS

Results showed that the protective efficacy of GG on DN works together with hypoglycemia and suppressing oxidative stress and inflammation, which at least partly involved in APMK/SIRT1/NF-κB-dependent pathway.

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.

Diffusion Tensor Imaging in Rat Models of Preclinical Diabetic Nephropathy: A Preliminary Study

PURPOSE

This study aimed to investigate the value of diffusion tensor imaging to assess renal injury in a rat model of preclinical diabetic nephropathy.

METHODS

Twenty-eight male Sprague Dawley rats were divided into two groups: the normal control (NC) group of 10 rats and the diabetic nephropathy (DN) group of 18 rats. Eight weeks after diabetes induction by streptozotocin, 3.0-T magnetic resonance (MR) imaging (b = 0 and 600 s/mm², 15 diffusion directions) using a 32-channel knee coil was performed. After MR imaging, we measured serum creatinine, and collected double kidney tissues for pathology. The apparent diffusion coefficients(ADC) and fractional anisotropy(FA) values of the renal cortex and medulla were calculated for all kidneys. Physiological parameters, laboratory parameters, and imaging results were compared between the two groups.

RESULTS

All DN group animals developed hyperglycemia, polyuria, and emaciation. Serum creatinine was not significantly different between the groups (P > 0.05). Urinary albumin at 2, 4, and 8 weeks was higher in the DN group than in the NC group but <20 µg/min (P < 0.05). Pathologically, renal damage in the DN rats was observed. The ADC value was significantly increased in DN animals in the cortex (1.75×10^-3mm²/s),medulla(1.53×10^-3mm²/s)compared with NC group(cortex, 1.52×10^-3mm²/s; medulla,1.35×10^-3mm²/s). The FA value was significantly reduced in DN animals in the cortex (0.21),medulla(0.25)compared with NC group(cortex,0.26;medulla,0.3).

CONCLUSIONS

Increased apparent diffusion coefficients and decreased fractional anisotropy values on diffusion tensor imaging were associated with preclinical DN. Diffusion tensor imaging may be useful in early, non-invasive, quantitative detection, and therapy monitoring of DN.

Lotus (Nelumbo nucifera) seedpod extract inhibits cell proliferation and induces apoptosis in non-small cell lung cancer cells via downregulation of Axl

Non-small-cell lung cancer (NSCLC) is the most frequent cause of cancer-related death. In this study, we found the anticancer activity of lotus seedpod extract (LSPE) in NSCLC cells, since LSPE treatment inhibited cell proliferation of A549 and H460 cells in a dose-dependent manner and the clonogenic activities of LSPE-treated cells were also reduced. In LSPE-treated cells, the cleavage of poly (ADP-ribose) polymerase (PARP) and phosphorylation of H2X, were also observed, indicating the pro-apoptotic effect of LSPE. Next, we found that LPSE treatment diminished the levels of protein and mRNA of Axl, a receptor tyrosine kinase (RTK) that transduces critical signals for cell proliferation and inhibition of apoptosis. The promoter activity of Axl was found to be dose-dependently decreased in response to LSPE treatment, implying that LSPE inhibited Axl gene expression at transcriptional level. In addition, Axl overexpression was found to decrease the effects of LSPE on inhibition of cell proliferation and colony formation as well as induction of PARP cleavage and phosphorylation of H2AX, while the same activities of LPSE were increased by knockdown of Axl gene expression, indicating that the antiproliferative and pro-apoptotic effect of LSPE is inversely proportional to the protein level of Axl. Taken together, we found that the LSPE suppressed cell proliferation and induced apoptosis of NSCLC cells, which is attenuated or augmented by overexpression or RNA interference of Axl expression, respectively. Our data suggest that Axl is a novel therapeutic target of LSPE to inhibit cell proliferation and promote apoptosis in NSCLC cells. PRACTICAL APPLICATIONS: In this study, lotus seedpod extract (LSPE) was found to have the cytotoxic and apoptosis-inducing potentials in non-small-cell lung cancer (NSCLC) cells. LSPE downregulated the Axl expression at transcriptional level and the effects of LSPE on cell proliferation as well as apoptosis were affected by Axl protein level. Therefore, the inference of Axl-mediated intracellular signals by LSPE must be a novel approach to control NSCLC. Since our data imply that LSPE contains bioactive compounds targeting Axl, further studies to elucidate these compounds might discover a potent therapeutic agent.

Improvement of Hypertriglyceridemia by Roasted Nelumbinis folium in High Fat/High Cholesterol Diet Rat Model

Hypertriglyceridemia is a condition characterized by high triglyceride levels and is a major risk factor for the development of cardiovascular diseases. The present study was designed to investigate the inhibitory effect of roasted Nelumbinis folium (RN), which is a medicinal substance produced by heating lotus leaves, on lipid metabolism in high fat/cholesterol (HFC) diet-induced hypertriglyceridemia. Except for those in the control group, Sprague–Dawley rats were fed an HFC diet for four weeks to induce hypertriglyceridemia. During the next nine weeks, the control, regular diet; HFC, HFC diet, FLU, fluvastatin (3 mg/kg/day); RNL, RN (100 mg/kg/day); RNH, RN (200 mg/kg/day) were orally administered together with the diet, and the experiments were conducted for a total of 13 weeks. The weight of the epididymal adipose tissue, liver, and heart of rats in the HFC diet group significantly increased compared to those in the control group but improved in the RN-treated group. It was also confirmed that vascular function, which is damaged by an HFC diet, was improved after RN treatment. The levels of insulin, glucose, triglycerides, total cholesterol, and low-density lipoprotein increased in the HFC diet group compared to those in the control group, while the administration of RN attenuated these parameters. In addition, the administration of RN significantly reduced the gene expression of both LXR and SREBP-1, which indicated the inhibitory effect of the biosynthesis of triglycerides caused by RN. The results indicated that RN administration resulted in an improvement in the overall lipid metabolism and a decrease in the concentration of triglycerides in the HFC diet-induced rat model of hypertriglyceridemia. Therefore, our findings suggest that the RN can be a candidate material to provide a new direction for treating hypertriglyceridemia.

Anti-Obesity Effects of a Prunus persica and Nelumbo nucifera Mixture in Mice Fed a High-Fat Diet

Prunus persica and Nelumbo nucifera are major crops cultivated worldwide. In East Asia, both P. persica flowers and N. nucifera leaves are traditionally used for therapeutic purposes and consumed as teas for weight loss. Herein, we investigated the anti-obesity effects of an herbal extract mixture of P. persica and N. nucifera (HT077) and the underlying mechanism using a high-fat diet (HFD)-induced obesity model. Male C57BL/6 mice were fed a normal diet, HFD, HFD containing 0.02% orlistat (positive control), or HFD containing 0.1, 0.2, or 0.4% HT077 for 12 weeks. HT077 significantly reduced final body weights, weight gain, abdominal fat weights, liver weights, and hepatic levels of triglycerides and total cholesterol. HT077 also lowered glucose, cholesterol, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and leptin levels and increased AST/ALT and adiponectin/leptin ratios and adiponectin levels. Real-time polymerase chain reaction analysis showed that HT077 decreased the expression of lipogenic genes and increased the expression of fatty acid oxidation-related genes in adipose tissue. Our results indicate that HT077 exerts anti-obesity effects and prevents the development of obesity-related metabolic disorders. These beneficial effects might be partially attributed to ameliorating adipokine imbalances and regulating lipid synthesis and fatty acid oxidation in adipose tissue.

Therapeutic application of nutraceuticals in diabetic nephropathy: Current evidence and future implications

Diabetes mellitus (DM) is a common metabolic disease which may cause several complications, such as diabetic nephropathy (DN). The routine medical treatments used for DM are not effective enough and have many undesirable side effects. Moreover, the global increased prevalence of DM makes researchers try to explore potential complementary or alternative treatments. Nutraceuticals, as natural products with pharmaceutical agents, have a wide range of therapeutic properties in various pathologic conditions such as DN. However, the exact underlying mechanisms have not been fully understood. The purpose of this review is to summarize recent findings on the effect of nutraceuticals on DN.

1,25(OH)2D3 provides protection against diabetic kidney disease by downregulating the TLR4-MyD88-NF-κB pathway

The over-activation of Toll-like receptors (TLRs) is a typical immune response to injury. Previous work has suggested that controlling the over-activation of TLR4-MyD88-NF-κB may represent a new therapeutic option for diabetic kidney disease (DKD). 1,25(OH)₂D₃ has also been shown to exert a protective effect on DKD, although the mechanism involved has yet to be elucidated. The aim of this study was to investigate whether 1,25(OH)₂D₃ protects against DKD by down-regulating the innate immune TLR-NF-κB pathway. NRK-52E cells were cultured under normal or high-glucose conditions. We then used siRNA to knock down TLR4 expression under high-glucose conditions. NRK-52E cells cultured under high-glucose conditions, and streptozotocin (STZ)-induced diabetic rats, were treated with different doses of 1,25(OH)₂D₃ and used as in vitro and in vivo models, respectively. Renal biochemical indicators were then measured to evaluate the influence of 1,25(OH)₂D₃ treatment on DKD in diabetic rats. Histological analysis was also performed to determine the extent of infiltration by inflammatory cells and tubulointerstitial fibrosis. Using RT-qPCR, western blotting, immunohistochemistry and immunofluorescence, we determined the expression levels of TLR4, MyD88, NF-κB p65, MCP-1 and α-SMA to investigate whether 1,25(OH)₂D₃ could reduce the development of tubulointerstitial fibrosis. Knocking down TLR4 abolished the tubulointerstitial fibrosis caused by high-glucose conditions. High doses of 1,25(OH)₂D₃ consistently reduced the expression of TLR4-MyD88-NF-κB in NRK-52E cells. Moreover, high doses of 1,25(OH)₂D₃ had an obvious protective effect on kidney injury and inhibited the infiltration of inflammatory cells and tubulointerstitial fibrosis in diabetic rats. In conclusion, high doses of 1,25(OH)₂D₃ protected against tubulointerstitial fibrosis both in vitro and in vivo by downregulating the expression of TLR4-MyD88-NF-κB.

Protective effect of EX-527 against high-fat diet-induced diabetic nephropathy in Zucker rats

High-fat diet (HFD)-induced obesity is implicated in diabetic nephropathy (DN). EX-527, a selective Sirtuin 1 (SIRT1) inhibitor, has multiple biological functions; however, its protective effect against DN is yet to be properly understood. This study was aimed to explore the protective effect of EX-527 against DN in HFD-induced diabetic Zucker (ZDF) rats. After 21 weeks of continually feeding HFD to the rats, the apparent characteristics of progressive DN were observed, which included an increase in kidney weight (~160%), hyperglycemia, oxidative stress, and inflammatory cytokines, and subsequent renal cell damage. However, the administration of EX-527 for 10 weeks significantly reduced the blood glucose concentration and kidney weight (~59%). Furthermore, EX-527 significantly reduced the serum concentration of transforming growth factor-β1 (49%), interleukin (IL)-1β (52%), and IL-6 in the HFD-fed rats. Overall, the antioxidant activities significantly increased, and oxidative damage to lipids or DNA was suppressed. Particularly, EX-527 significantly reduced blood urea nitrogen (81%), serum creatinine (71%), microalbumin (43%), and urinary excretion of protein-based biomarkers. Histopathological examination revealed expansion of the extracellular mesangial matrix and suppression of glomerulosclerosis following EX-527 administration. EX-527 downregulated the expression of α-SMA (~64%), TGF-β (25%), vimentin, α-tubulin, fibronectin, and collagen-1 in the kidneys of the HFD-fed rats. Additionally, EX-527 substantially reduced claudin-1 and SIRT1 expression, but increased the expression of SIRT3 in the kidneys of the HFD-fed rats. EX-527 also inhibited the growth factor receptors, including EGFR, PDGFR-β, and STAT3, which are responsible for the anti-fibrotic effect of SIRT-1. Therefore, the administration of EX-527 protects against HFD-induced DN.

Umbilical Cord-Derived Mesenchymal Stem Cells Ameliorate Nephrocyte Injury and Proteinuria in a Diabetic Nephropathy Rat Model

Mesenchymal stem cells (MSCs) are shown to alleviate renal injury of diabetic nephropathy (DN) in rats. However, the underlying mechanism of this beneficial effect is not fully understood. The aims of this study are to evaluate effects of umbilical cord-derived mesenchymal stem cells (UC-MSCs) on renal cell apoptosis in streptozotocin- (STZ-) induced diabetic rats and explore the underlying mechanisms. Characteristics of UC-MSCs were identified by flow cytometry and differentiation capability. Six weeks after DN induction by STZ injection in Sprague-Dawley rats, the DN rats received UC-MSCs once a week for consecutive two weeks. DN-related physical and biochemical parameters were measured at 2 weeks after UC-MSC infusion. Renal histological changes were also assessed. Moreover, the apoptosis of renal cells and expression of apoptosis-related proteins were evaluated. Compared with DN rats, rats treated with UC-MSCs showed suppressed increase in 24-hour urinary total protein, urinary albumin to creatinine ratio, serum creatinine, and blood urea nitrogen. UC-MSC treatment ameliorated pathological abnormalities in the kidney of DN rats as evidenced by H&E, PAS, and Masson Trichrome staining. Furthermore, UC-MSC treatment reduced apoptosis of renal cells in DN rats. UC-MSCs promoted expression of antiapoptosis protein Bcl-xl and suppressed expression of high mobility group protein B1 (HMGB1) in the kidney of DN rats. Most importantly, UC-MSCs suppressed upregulation of thioredoxin-interacting protein (TXNIP), downregulation of thioredoxin 1 (TRX1), and activation of apoptosis signal-regulating kinase 1 (ASK1) and P38 MAPK in the kidney of DN rats. Our results suggest that UC-MSCs could alleviate nephrocyte injury and albuminuria of DN rats through their antiapoptotic property. The protective effects of UC-MSCs may be mediated by inhibiting TXNIP upregulation in part.