Propyl gallate plays a nephroprotective role in early stage of diabetic nephropathy associated with suppression of glomerular endothelial cell proliferation and angiogenesis

Effects of antioxidants on diabetic kidney diseases: mechanistic interpretations and clinical assessment

Diabetic kidney disease (DKD) is more prevalent with an increase in diabetes mellitus. Oxidative stress is a major factor in the occurrence and progression of DKD. Defending against oxidative stress and restoring antioxidant defense might be key to preventing and treating DKD. The purpose of this article is to provide an explanation of how oxidative stress affects DKD, conduct a systematic review and meta-analysis on DKD, and examine the effect of antioxidants on the disease. An analysis of 19 randomized controlled trials showed that the use of antioxidants could reduce UAE (albumin excretion rate) in patients with DKD (SMD: - 0.31; 95% CI [- 0.47, - 0.14], I² = 0%), UACR (urine albumin/creatinine ratio) (SMD: - 0.60; 95% CI [- 1.15, - 0.06], I² = 89%), glycosylated hemoglobin (hbA1c) (MD: - 0.61; 95% CI [- 1.00, - 0.21], I² = 93%) and MDA (malonaldehyde) (SMD:-1.05; 95% CI [- 1.87, - 0.23], I² = 94%), suggesting that antioxidants seemed to have therapeutic effects in patients with DKD, especially in reducing proteinuria and hbA1c. The purpose of this study is to provide new targets and ideas for drug research and clinical treatment of DKD.

Nephroprotective effect of Pleurotus ostreatus extract against cadmium chloride toxicity in rats

Cadmium, present in the environment, accumulates in different organs of animals and humans, and has deleterious effects on the kidney. In this study, we investigated the protective effects of the methanolic extract of Pleurotus ostreatus in comparison with silymarin on renal function in cadmium-intoxicated rats for five days. Rats intraperitoneally injected with cadmium chloride (1 mg/kg). These rats were treated with either P. ostreatus extract (200 mg/kg) or silymarin to investigate the protective effects of the extract. Cadmium treatment induced significant histopathological impairments and increased cadmium levels, DNA fragmentation, and renal oxidative stress. However, treatment with P. ostreatus extract or silymarin improved the pathology, reduced the level of cadmium in renal tissue, and restored DNA fragmentation. In addition, a significant reduction in lipid peroxidation and reactive oxygen species levels, and a significant increase in the levels of glutathione and catalase activity were observed. Thus, protective effects of P. ostreatus extract to its components. Chromatographic analysis of the P. ostreatus confirmed the presence of five phenolics (gallic acid, chlorogenic acid, catechin, propyl gallate, and cinnamic acid) that exhibit strong antioxidant properties as free radical scavengers. Therefore, our findings demonstrate that treatment with P. ostreatus extract protects against cadmium-induced nephrotoxicity in female rats.

Tannins and vascular complications of Diabetes: An update

BACKGROUND

Diabetes mellitus is a chronic metabolic disorder associated with persistent increased level of glucose in the blood. According to a report by World Health Organisation (WHO), prevalence of diabetes among adults over 18 years of age had reached to 8.5% in year 2014 which was 4.7% in 1980s. The Prolong increased level of glucose in blood leads to development of microvascular (blindness, nephropathy and neuropathy) and macrovascular (cardiovascular and stroke) degenerative complications because of uncontrolled level of glucose in blood. This also leads to the progression of oxidative stress and affecting metabolic, genetic and haemodynamic system by activation of polyol pathway, protein kinase C pathway, hexosamine pathway and increases advanced glycation end products (AGEs) formation. Diabetes mellitus and its associated complications are one of the major leading causes of mortality worldwide. Various natural products like alkaloids, glycosides, flavonoids, terpenoids and polyphenols are reported for their activity in management of diabetes and its associated diabetic complications. Tannins are systematically studied by many researchers in past few decades for their effect in diabetes and its complications.

AIM

The present review was designed to compile the data of tannins and their beneficial effects in the management of diabetic complications.

METHOD

Literature search was performed using various dataset like pubmed, EBSCO, proQuest Scopus and selected websites including the National Institutes of Health (NIH) and the World Health Organization (WHO).

RESULTS

Globally, more than 400 natural products have been investigated in diabetes and its complications. Tannins are the polyphenolic compounds present in many medicinal plants and various dietary sources like fruits, nuts, grains, spices and beverages. Various reports have shown that compounds like gallic acid, ellagic acid, catechin, epicatechin and procynidins from medicinal plants play major role in controlling progression of diabetes and its related complications by acting on molecular pathways and key targets involved in progression. Many chemists used above mentioned phyto-constituents as a pharmacophore for the developing new chemical entities having higher therapeutic benefits in management of diabetic complications.

CONCLUSION

This review focuses on the role of various tannins in prevention and management of diabetic complications like diabetic nephropathy, diabetic neuropathy, diabetic retinopathy and diabetic cardiomyopathy. It will help researchers to find some leads for the development of new cost effective therapy using dietary source for the management of diabetic complications.

Quercetin nanoparticle complex attenuated diabetic nephropathy via regulating the expression level of ICAM-1 on endothelium

The purpose of the study was to reveal the therapeutic effect of quercetin (QUE) nanoparticle complex on diabetic nephropathy (DN) by regulating the expression of intercellular adhesion molecular-1 (ICAM-1) on endothelium as compared to free QUE. QUE 10 mg/kg as a single abdominal subcutaneous injection daily for 8 weeks continuously in diabetic rats and 10 mg/kg QUE nanoparticle complex as a single abdominal subcutaneous injection every 5 days, continuously administered for 8 weeks to diabetic rats. Blood and left kidneys were collected; pathological change of kidney, renal function, oxidative stress level, blood glucose level, serum lipid, urine protein, and albumin/creatinine ratio were measured; and neutrophil adhesion, ICAM-1 expression, and CD11b⁺ cells infiltration were observed. Both QUE and QUE nanoparticle complex preconditioning ameliorated the pathological damage of kidney and improved renal function, alleviated renal oxidative stress injury, restricted inflammatory cells infiltration, and downregulated the ICAM-1 expression as compared to DN group, while QUE nanoparticle complex significantly alleviated this effect.

The role of Jagged1/Notch pathway-mediated angiogenesis of hepatocarcinoma cells in vitro, and the effects of the spleen-invigorating and blood stasis-removing recipe

The objective of this study was to observe the effect of Jagged1/Notch pathway-mediated angiogenesis on the in vitro proliferation of hepatocellular carcinoma cells, and the effect and possible mechanism of the spleen-invigorating and blood stasis-removing recipe. Spleen-invigorating and blood stasis-removing recipe serum from SPF grade nude mice was prepared, and the fingerprint of the drugs of the spleen-invigorating and blood stasis-removing recipe and drug serum were identified by HPLC. SMMC-7721 human hepatocellular carcinoma cells were divided into the normal control group, DAPT inhibitor control group, and drug serum group according to the different treatments. The Cell Counting Kit-8 (CCK-8) method was used to determine cell proliferation ability, and angiogenesis was observed under an inverted microscope. The expression of Jagged1, Notch1, and VEGF was measured by qPCR and western blot analysis. The interaction of Jagged1 and Notch1 was detected by Co-IP. The CCK-8 assay indicated that cell proliferation was inhibited in response to drug treatment (P<0.01). The expression of Jagged1, Notch1, and VEGF in the drug serum group was significantly lower than in the normal control group (P<0.01). Compared with the control group, the new vascular area of the DAPT inhibitor control group and drug serum group was smaller, and the blood vessels of the DAPT inhibitor control group and drug serum group were more sparse. The levels of Jagged1, Notch1, VEGF protein and the interaction between Jagged1 and Notch1 in the DAPT inhibitor control group and drug serum group were significantly lower than in the control serum group (P<0.01). In conclusion, the spleen-invigorating and blood stasis-removing recipe can inhibit the proliferation of hepatocellular carcinoma cells, and tumor angiogenesis in vitro. The function is related to the reduced expression of Jagged1, reduced interaction between Jagged1 and Notch1, and the reduced expression and activity of VEGF.

Changes of serum Mir-217 and the correlation with the severity in type 2 diabetes patients with different stages of diabetic kidney disease

The aim of this study is to investigate the correlation between serum microRNA-217 and the severity of diabetic kidney disease determined by albuminuria. Four hundred ninety five type 2 diabetes patients were divided into three groups: normoalbuminuric group, microalbuminuric group, and macroalbuminuric group. Serum microRNA-217 levels were validated by real-time polymerase chain reaction. Serum silent information regulator 1, Hypoxia-inducible factor-1α and vascular endothelial growth factor were determined by enzyme-linked immunosorbent assay. Compared with control, serum microRNA-217 levels were significantly increased in type 2 diabetes patients and gradually increased in patients of normoalbuminuric, microalbuminuric, and macroalbuminuric groups (P < 0.01). Moreover, increased levels of serum microRNA-217, hypoxia-inducible factor-1α, vascular endothelial growth factor, diabetes mellitus duration, fasting blood glucose, fasting insulin, homeostasis model assessment for insulin resistance, glycated hemoglobin, low-density lipoprotein, total cholesterol, triglyceride, uric acid, serum creatinine, blood urea nitrogen, and decreased levels of serum silent information regulator 1 and high-density lipoprotein were significantly correlated with Ln(ACR) (P < 0.05). In addition, serum microRNA-217 was positively correlated with diabetes mellitus duration, homeostasis model assessment for insulin resistance, glycated hemoglobin, Ln(ACR), low-density lipoprotein, total cholesterol, triglyceride, uric acid, serum creatinine, blood urea nitrogen, hypoxia-inducible factor-1α, vascular endothelial growth factor (P < 0.05), and negatively correlated with serum silent information regulator 1 (P = 0.002). Our findings suggest that microRNA-217 may have an association with the development of proteinuria in type 2 diabetes patients. Serum microRNA-217 may be involved in the development of diabetic kidney disease by promoting chronic inflammation, renal fibrosis, and angiogenesis.

Chronic intermittent hypobaric hypoxia ameliorates diabetic nephropathy through enhancing HIF1 signaling in rats

AIM

Our previous study demonstrated that chronic intermittent hypobaric hypoxia (CIHH) had anti-diabetes effect. The present study was to explore the renal protective effect of CIHH in diabetic rats.

METHODS

Sprague-Dawley rats were randomly divided into three groups: diabetes mellitus group (DM, induced by high-fat diet combined with low-dose streptozotocin), diabetes plus CIHH treatment group (DM+CIHH, simulated 5000-m altitude, 6h per day for 28days, after diabetes model confirmed) and control group (CON). Systolic arterial blood pressure (SAP), blood biochemicals, urinary albumin, and histopathology of kidney were determined. The superoxide dismutase (SOD) activity, malondialdehyde (MDA) level, protein levels of hypoxia induced factors (HIFs) and transforming growth factor β1 (TGF-β1) in kidney were assayed.

RESULTS

The increased SAP, urinary albumin, hyperplasia of glomerular, fibrosis in mesangial and glomerular, and abnormal lipid metabolism in diabetic rats were ameliorated by CIHH treatment. And decreased superoxide dismutase (SOD) activity and increased malondialdehyde (MDA) level in diabetic kidney were reversed in CIHH-treated DM rats. In addition up-regulated TGF-β1 and down-regulated HIF1α in diabetic kidney returned back to normal level in CIHH-treated DM rats.

CONCLUSIONS

These data demonstrated for the first time that CIHH had protective effects against the early stage damage of diabetic nephropathy through activating HIF1 signaling, improving anti-oxidation and inhibiting TGF-β1 signaling in diabetic rats.

Reversibility of endothelial dysfunction in diabetes: role of polyphenols

The endothelium, a thin single sheet of endothelial cells, is a metabolically active layer that coats the inner surface of blood vessels and acts as an interface between the circulating blood and the vessel wall. The endothelium through the secretion of vasodilators and vasoconstrictors serves as a critical mediator of vascular homeostasis. During the development of the vascular system, it regulates cellular adhesion and vessel wall inflammation in addition to maintaining vasculogenesis and angiogenesis. A shift in the functions of the endothelium towards vasoconstriction, proinflammatory and prothrombic states characterise improper functioning of these cells, leading to endothelial dysfunction (ED), implicated in the pathogenesis of many diseases including diabetes. Major mechanisms of ED include the down-regulation of endothelial nitric oxide synthase levels, differential expression of vascular endothelial growth factor, endoplasmic reticulum stress, inflammatory pathways and oxidative stress. ED tends to be the initial event in macrovascular complications such as coronary artery disease, peripheral arterial disease, stroke and microvascular complications such as nephropathy, neuropathy and retinopathy. Numerous strategies have been developed to protect endothelial cells against various stimuli, of which the role of polyphenolic compounds in modulating the differentially regulated pathways and thus maintaining vascular homeostasis has been proven to be beneficial. This review addresses the factors stimulating ED in diabetes and the molecular mechanisms of natural polyphenol antioxidants in maintaining vascular homeostasis.

Exosomes secreted by human urine-derived stem cells could prevent kidney complications from type I diabetes in rats

Background

Diabetic nephropathy is one of the most serious complications in patients with diabetes. At present, there are no satisfactory treatments available for diabetic nephropathy. Stem cells are currently the main candidates for the development of new treatments for diabetic nephropathy, as they may exert their therapeutic effects mainly through paracrine mechanisms. Exosomes derived from stem cells have been reported to play an important role in kidney injury. In this article, we try to investigate whether exosomes retrieved from urine stem cells could itself prevent diabetic nephropathy at an early stage in vivo and in vitro.

Methods

Exosomes from conditioned medium of urine-derived stem cells (USCs-Exo) were isolated using ultrafiltration-combined purification methods. USCs-Exo were then verified by morphology, size, and specific biomarkers using transmission electron microscopy, tunable resistive pulse sensing analysis, and western blotting. After establishment of the streptozotocin-induced Sprague–Dawley rat model, the effects of USCs-Exo on kidney injury and angiogenesis were observed via weekly tail intravenous injection of USCs-Exo or control until 12 weeks. In vitro, podocytes cultured in high-glucose medium were treated with USCs-Exo to test the protective effect of USCs-Exo on podocytic apoptosis. Meanwhile, the potential factors in promoting vascular regeneration in USCs-Exo and urine-derived stem cell conditioned medium were investigated by enzyme-linked immunosorbent assay.

Results

Urine-derived stem cells were cultured and were verified by positive markers for CD29, CD73, CD90 and CD44 antigens, and negative markers for CD34, CD45 and HLA-DR. USCs-Exo were approximately 50–100 nm spherical vesicles, and the specific markers included CD9, CD63 and CD81. Intravenous injections of USCs-Exo could potentially reduce the urine volume and urinary microalbumin excretion, prevent podocyte and tubular epithelial cell apoptosis, suppress the caspase-3 overexpression and increase glomerular endothelial cell proliferation in diabetic rats. In addition, USCs-Exo could reduce podocytic apoptosis induced by high glucose in vitro. USCs-Exo contained the potential factors, including growth factor, transforming growth factor-β1, angiogenin and bone morphogenetic protein-7, which may be related with vascular regeneration and cell survival.

Conclusion

USCs-Exo may have the potential to prevent kidney injury from diabetes by inhibiting podocyte apoptosis and promoting vascular regeneration and cell survival.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0287-2) contains supplementary material, which is available to authorized users.

Gallic acid ameliorates renal functions by inhibiting the activation of p38 MAPK in experimentally induced type 2 diabetic rats and cultured rat proximal tubular epithelial cells

Diabetic nephropathy (DN) is one of the leading causes of morbidity and mortality in diabetic patients that accounts for about 40% of deaths in type 2 diabetes. p38 mitogen activated protein kinase (p38 MAPK), a serine-threonine kinase, plays an important role in tissue inflammation and is known to be activated under conditions of oxidative stress and hyperglycemia. The role of p38 MAPK has been demonstrated in DN, and its inhibition has been suggested as an alternative approach in the treatment of DN. In the present study, we investigated the nephroprotective effects of an anti-inflammatory phenolic compound, gallic acid (GA, 3,4,5-trihydroxybenzoic acid), in high fat diet/streptozotocin (HFD/STZ) induce type 2 diabetic wistar albino rats. GA (25 mg/kgbw and 50 mg/kgbw, p.o.) treatment for 16 weeks post induction of diabetes led to a significant reduction in the levels of blood glucose, HbA1c, serum creatinine, blood urea nitrogen and proteinuria as well as a significant reduction in the levels of creatinine clearance. GA significantly inhibited the renal p38 MAPK and nuclear factor kappa B (N-κB) activation as well as significantly reduced the levels of renal transforming growth factor beta (TGF-β) and fibronectin. Treatment with GA resulted in a significant reduction in the serum levels of proinflammatory cytokines viz. interleukin 1 beta (IL-1β), IL-6 and tumor necrosis factor alpha (TNF-α). Moreover, GA significantly lowered renal pathology and attenuated renal oxidative stress. In cultured rat NRK 52E proximal tubular epithelial cells, GA treatment inhibited high glucose induced activation of p38 MAPK and NF-κB as well as suppressed proinflammatory cytokine synthesis. The results of the present study provide in vivo and in vitro evidences that the p38 MAPK pathway plays an important role in the pathogenesis of DN, and GA attenuates the p38 MAPK-mediated renal dysfunction in HFD/STZ induced type 2 diabetic rats.

The attenuation of Moutan Cortex on oxidative stress for renal injury in AGEs-induced mesangial cell dysfunction and streptozotocin-induced diabetic nephropathy rats

Oxidative stress (OS) has been regarded as one of the major pathogeneses of diabetic nephropathy (DN) through damaging kidney which is associated with renal cells dysfunction. The aim of this study was to investigate whether Moutan Cortex (MC) could protect kidney function against oxidative stress in vitro or in vivo. The compounds in MC extract were analyzed by HPLC-ESI-MS. High-glucose-fat diet and STZ (30 mg kg⁻¹) were used to induce DN rats model, while 200 μg mL⁻¹ AGEs were for HBZY-1 mesangial cell damage. The treatment with MC could significantly increase the activity of SOD, glutathione peroxidase (GSH-PX), and catalase (CAT). However, lipid peroxidation malondialdehyde (MDA) was reduced markedly in vitro or in vivo. Furthermore, MC decreased markedly the levels of blood glucose, serum creatinine, and urine protein in DN rats. Immunohistochemical assay showed that MC downregulated significantly transforming growth factor beta 2 (TGF-β2) protein expression in renal tissue. Our data provided evidence to support this fact that MC attenuated OS in AGEs-induced mesangial cell dysfunction and also in high-glucose-fat diet and STZ-induced DN rats.