Thiazolidinedione ameliorates renal injury in experimental diabetic rats through anti-inflammatory effects mediated by inhibition of NF-kappaB activation

Evaluation of the Effect of an α-Adrenergic Blocker, a PPAR-γ Receptor Agonist, and a Glycemic Regulator on Chronic Kidney Disease in Diabetic Rats

Diabetic nephropathy (DN) is a globally widespread complication of diabetes mellitus (DM). Research indicates that pioglitazone and linagliptin mitigate the risk of DN by reducing inflammation, oxidative stress, and fibrosis. The role of tamsulosin in DN is less studied, but it may contribute to reducing oxidative stress and inflammatory responses. The protective effects of combining pioglitazone, linagliptin, and tamsulosin on the kidneys have scarcely been investigated. This study examines the individual and combined effects of these drugs on DN in Wistar rats. Diabetic rats were treated with tamsulosin, pioglitazone, and linagliptin for six weeks. We assessed food and water intake, estimated glomerular filtration rate (eGFR), histological markers, urea, creatinine, glucose, NF-κB, IL-1, IL-10, TGF-β, and Col-IV using immunofluorescence and qPCR. The DN group exhibited hyperglycaemia, reduced eGFR, and tissue damage. Tamsulosin and linagliptin improved eGFR, decreased urinary glucose, and repaired tissue damage. Pioglitazone and its combinations restored serum and urinary markers and reduced tissue damage. Linagliptin lowered serum creatinine and tissue injury. In conclusion, tamsulosin, linagliptin, and pioglitazone demonstrated renoprotective effects in DN.

Cladophora glomerata Kützing extract exhibits antioxidant, anti-inflammation, and anti-nitrosative stress against impairment of renal organic anion transport in an in vivo study

BACKGROUND/OBJECTIVES

Cladophora glomerata extract (CGE), rich in polyphenols, was reported to exhibit antidiabetic and renoprotective effects by modulating the functions of protein kinases-mediated organic anion transporter 1 (Oat1) and 3 (Oat3) in rats with type 2 diabetes mellitus (T2DM). Nevertheless, the antioxidant effects of CGE on such renoprotection have not been investigated. This study examined the mechanisms involved in the antioxidant effects of CGE on renal organic anion transport function in an in vivo study.

MATERIALS/METHODS

Diabetes was induced in the rats through a high-fat diet combined with a single dose of 40 mg/kg body weight (BW) streptozotocin. Subsequently, normal-diet rats were supplemented with a vehicle or 1,000 mg/kg BW of CGE, while T2DM rats were supplemented with a vehicle, CGE, or 200 mg/kg BW of vitamin C for 12 weeks. The study evaluated the general characteristics of T2DM and renal oxidative stress markers. The renal organic transport function was assessed by measuring the para-aminohippurate (PAH) uptake using renal cortical slices and renal inflammatory cytokine expression in the normal diet (ND) and ND + CGE treated groups.

RESULTS

CGE supplementation significantly reduced hyperglycemia, hypertriglyceridemia, insulin resistance, and renal lipid peroxidation in T2DM rats. This was accompanied by the normalization of high expressions of renal glutathione peroxidase and nuclear factor kappa B by CGE and vitamin C. The renal anti-inflammation of CGE was evidenced by the reduction of tumor necrosis factor-1α and interleukin-1β. CGE directly blunted sodium nitroprusside-induced renal oxidative/nitrosative stresses and mediated the PAH uptake in the normally treated CGE in rats was particularly noteworthy. These data also correlated with reduced nitric oxide production, highlighting the potential of CGE as a therapeutic agent for managing T2DM-related renal complications.

CONCLUSION

These findings suggest that CGE has antidiabetic effects and directly prevents diabetic nephropathy through oxidative/nitrosative stress pathways.

Unveiling biomarkers and therapeutic targets in IgA nephropathy through large-scale blood transcriptome analysis

INTRODUCTION

IgA nephropathy (IgAN) is the most prevalent form of glomerulonephritis. Unfortunately, molecular biomarkers for IgAN derived from omics studies are still lacking. This research aims to identify critical genes associated with IgAN through large-scale blood transcriptome analysis.

METHODS

We constructed novel blood transcriptome profiles from peripheral blood mononuclear cells (PBMCs) of 53 Chinese IgAN patients and 28 healthy individuals. Our analysis included GO, KEGG, and GSEA for biological pathways. We analyzed immune cell profiles with CIBERSORT and constructed PPI networks with STRING, visualized in Cytoscape. Key differentially expressed genes (DEGs) were identified using CytoHubba and MCODE. We assessed the correlation between gene expressions and clinical data to evaluate clinical significance and identified hub genes through machine learning, validated with an open-access dataset. Potential drugs were explored using the CMap database.

RESULTS

We identified 333 DEGs between IgAN patients and healthy controls, mainly related to immune response and inflammation. Key pathways included NK cell mediated cytotoxicity, complement and coagulation cascades, antigen processing, and B cell receptor signaling. Cytoscape revealed 16 clinically significant genes (including KIR2DL1, KIR2DL3, VISIG4, C1QB, and C1QC, associated with sub-phenotype and prognosis). Machine learning identified two hub genes (KLRC1 and C1QB) for a diagnostic model of IgAN with 0.92 accuracy, validated at 1.00 against the GSE125818 dataset. Sirolimus, calcifediol, and efaproxiral were suggested as potential therapeutic agents.

CONCLUSION

Key DEGs, particularly VISIG4, KLRC1, and C1QB, emerge as potential specific markers for IgAN, paving the way for future targeted personalized treatment options.

The role and therapeutic potential of macrophages in the pathogenesis of diabetic cardiomyopathy

This review provides a comprehensive analysis of the critical role played by macrophages and their underlying mechanisms in the progression of diabetic cardiomyopathy (DCM). It begins by discussing the origins and diverse subtypes of macrophages, elucidating their spatial distribution and modes of intercellular communication, thereby emphasizing their significance in the pathogenesis of DCM. The review then delves into the intricate relationship between macrophages and the onset of DCM, particularly focusing on the epigenetic regulatory mechanisms employed by macrophages in the context of DCM condition. Additionally, the review discusses various therapeutic strategies aimed at targeting macrophages to manage DCM. It specifically highlights the potential of natural food components in alleviating diabetic microvascular complications and examines the modulatory effects of existing hypoglycemic drugs on macrophage activity. These findings, summarized in this review, not only provide fresh insights into the role of macrophages in diabetic microvascular complications but also offer valuable guidance for future therapeutic research and interventions in this field.

Leonurine alleviates vancomycin nephrotoxicity via activating PPARγ and inhibiting the TLR4/NF-κB/TNF-α pathway

Vancomycin (VCM) is the first-line antibiotic for severe infections, but nephrotoxicity limits its use. Leonurine (Leo) has shown protective effects against kidney damage. However, the effect and mechanism of Leo on VCM nephrotoxicity remain unclear. In this study, mice and HK-2 cells exposed to VCM were treated with Leo. Biochemical and pathological analysis and fluorescence probe methods were performed to examine the role of Leo in VCM nephrotoxicity. Immunohistochemistry, q-PCR, western blot, FACS, and Autodock software were used to verify the mechanism. The present results indicate that Leo significantly alleviates VCM-induced renal injury, morphological damage, and oxidative stress. Increased intracellular and mitochondrial ROS in HK-2 cells and decreased mitochondrial numbers in mouse renal tubular epithelial cells were reversed in Leo-administrated groups. In addition, molecular docking analysis using Autodock software revealed that Leo binds to the PPARγ protein with high affinity. Mechanistic exploration indicated that Leo inhibited VCM nephrotoxicity via activating PPARγ and inhibiting the TLR4/NF-κB/TNF-α inflammation pathway. Taken together, our results indicate that the PPARγ inhibition and inflammation reactions were implicated in the VCM nephrotoxicity and provide a promising therapeutic strategy for renal injury.

PPARα/δ dual agonist H11 alleviates diabetic kidney injury by improving the metabolic disorders of tubular epithelial cells

Diabetic kidney disease (DKD) is responsible for nearly half of all end-stage kidney disease and kidney failure is a major driver of mortality among patients with diabetes. To date, few safe and effective drugs are available to reverse the decline of kidney function. Kidney tubules producing energy by fatty acid metabolism are pivotal in development and deterioration of DKD. Peroxisome proliferator-activated receptors (PPARs), comprising PPARα, PPARδ and PPARγ play a senior role in the pathogenesis of DKD for their functions in glycemic control and lipid metabolism; whereas systemic activation of PPARγ causes serious side-effects in clinical settings. Compound H11 was a potent PPARα and PPARδ (PPARα/δ) dual agonist with potent and well-balanced PPARα/δ agonistic activity and a high selectivity over PPARγ. In this study, the potential therapeutic effects of compound H11 were determined in a db/db mouse model of diabetes. Expressions of PPARα and PPARδ in nuclei of tubules were markedly reduced in diabetes. Transcriptional changes of tubular cells showed that H11 was an effective PPARα/δ dual agonist taking effects both in vivo and in vitro. Systemic administration of H11 showed glucose tolerance and lipid metabolic benefits in db/db mice. Moreover, H11 treatment exerted protective effects on diabetic kidney injury. In addition to fatty acid metabolism, H11 also regulated diabetes-induced metabolic alternations of branch chain amino acid degradation and glycolysis. The present study demonstrated a crucial role of H11 in regulation of energy homeostasis and metabolism in glucose-treated tubular cells. Overall, compound H11 holds therapeutic promise for DKD.

LDP alleviates TKI-induced proteinuria through reversing the expression of RelA in renal tissues

Tyrosine kinase inhibitors (TKIs), as an important tumor therapy, can induce severe proteinuria that significantly affects anti-tumor therapy. Existing therapies against proteinuria induced by other etiologies are currently ineffective for TKI-induced proteinuria. It has been shown that various types of proteinuria are related to podocyte damage caused by changes in the RelA signaling pathway. Our experiments confirmed that TKIs activate the renal RelA signaling pathway, and induce death of podocytes and destruction of the glomerular filtration barrier. Here we found that Liuwei Dihuang Pill (LDP) attenuated the inflammatory injury of podocytes through inhibiting activation of RelA, and subsequently relieved TKI-related proteinuria and prevented the progression of TMA and FSGS. Our finding indicated that LDP may be effective for the treatment of TKI-induced proteinuria, which is clinically significant.

Immune responses in diabetic nephropathy: Pathogenic mechanisms and therapeutic target

Diabetic nephropathy (DN) is a chronic, inflammatory disease affecting millions of diabetic patients worldwide. DN is associated with proteinuria and progressive slowing of glomerular filtration, which often leads to end-stage kidney diseases. Due to the complexity of this metabolic disorder and lack of clarity about its pathogenesis, it is often more difficult to diagnose and treat than other kidney diseases. Recent studies have highlighted that the immune system can inadvertently contribute to DN pathogenesis. Cells involved in innate and adaptive immune responses can target the kidney due to increased expression of immune-related localization factors. Immune cells then activate a pro-inflammatory response involving the release of autocrine and paracrine factors, which further amplify inflammation and damage the kidney. Consequently, strategies to treat DN by targeting the immune responses are currently under study. In light of the steady rise in DN incidence, this timely review summarizes the latest findings about the role of the immune system in the pathogenesis of DN and discusses promising preclinical and clinical therapies.

The Role of Peroxisome Proliferator-Activated Receptors in Kidney Diseases

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors. Accumulating evidence suggests that PPARs may play an important role in the pathogenesis of kidney disease. All three members of the PPAR subfamily, PPARα, PPARβ/δ, and PPARγ, have been implicated in many renal pathophysiological conditions, including acute kidney injury, diabetic nephropathy, and chronic kidney disease, among others. Emerging data suggest that PPARs may be potential therapeutic targets for renal disease. This article reviews the physiological roles of PPARs in the kidney and discusses the therapeutic utility of PPAR agonists in the treatment of kidney disease.

The In Vitro Anti-Inflammatory Activities of Galangin and Quercetin towards the LPS-Injured Rat Intestinal Epithelial (IEC-6) Cells as Affected by Heat Treatment

Flavonols possess several beneficial bioactivities in vitro and in vivo. In this study, two flavonols galangin and quercetin with or without heat treatment (100 °C for 15-30 min) were assessed for their anti-inflammatory activities in lipopolysaccharide (LPS)-stimulated rat intestinal epithelial (IEC-6) cells and whether the heat treatment caused activity changes. The flavonol dosages of 2.5-20 μmol/L had no cytotoxicity on the cells but could enhance cell viability (especially using 5 μmol/L flavonol dosage). The flavonols could decrease the production of prostaglandin E2 and three pro-inflammatory cytokines interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α, and simultaneously promote the production of two anti-inflammatory cytokines IL-10 and transforming growth factor-β. The Western-blot results verified that the flavonols could suppress the LPS-induced expression of TLR4 and phosphorylated IκBα and p65, while the molecular docking results also illustrated that the flavonols could bind with TLR4 and NF-κB to yield energy decreases of -(21.9-28.6) kJ/mol. Furthermore, an inhibitor BAY 11-7082 blocked the NF-κB signaling pathway by inhibiting the expression of phosphorylated IκBα/p65 and thus mediated the production of IL-6/IL-10 as the flavonols did, which confirmed the assessed anti-inflammatory effect of the flavonols. Consistently, galangin had higher anti-inflammatory activity than quercetin, while the heated flavonols (especially those with longer heat time) were less active than the unheated counterparts to exert these target anti-inflammatory effects. It is highlighted that the flavonols could antagonize the LPS-caused IEC-6 cells inflammation via suppressing TLR4/NF-κB activation, but heat treatment of the flavonols led to reduced anti-inflammatory efficacy.

Nuclear Receptors and Transcription Factors in Obesity-Related Kidney Disease

Both obesity and chronic kidney disease are increasingly common causes of morbidity and mortality worldwide. Although obesity often co-exists with diabetes and hypertension, it has become clear over the past several decades that obesity is an independent cause of chronic kidney disease, termed obesity-related glomerulopathy. This review defines the attributes of obesity-related glomerulopathy and describes potential pharmacologic interventions. Interventions discussed include peroxisome proliferator-activated receptors, the farnesoid X receptor, the Takeda G-protein-coupled receptor 5, and the vitamin D receptor.

Emodin Attenuated the Kidney Damage of High-Fat-Diet Mice via the Upregulation of Glucagon-Like Peptide-1 Receptor

Objective

Secretion of glucagon-like peptide 1 (GLP-1) and its effect on target organs were impaired in individuals with obesity. However, its mechanism needs to be further studied. We aim to explore the roles of the receptor of GLP-1 (GLP-1R) involved in high-fat-diet- (HFD-) induced kidney damage improved by emodin.

Methods

Male C57bl/6 mice were fed with HFD diet and therapied by emodin. NRK-52E cells were cultured and treated with palmitic acid or low-density lipoprotein cholesterol (LDL-C). Emodin was used to remedy the NRK-52E cell damage. GW9662 was administrated to block the function of peroxisome proliferator-activated receptor γ (PPAR-γ). GLP-1 in the plasma was measured by ELISA. PPAR-γ and GLP-1R in the kidney and NRK-52E cells were detected by western blotting. The interaction between PPAR-γ protein and GLP-1R promoter regions was observed by chromatin immunoprecipitation (ChIP).

Results

Postprandial GLP-1 levels in plasma, as well as PPAR-γ and GLP-1R, decreased in kidney tissue of HFD mice, while they were reserved by emodin treatment. Although PPAR-γ and GLP-1R were not downregulated by LDL-C, they were suppressed by palmitic acid. Interestingly, GLP-1R mRNA was detected by PCR in the mixture pulled down with PPAR-γ antibody. Additionally, downregulation of PPAR-γ and GLP-1R by palmitic acid was remanded by emodin. Moreover, GW9662, an inhibitor of PPAR-γ, abolished the protective effect of emodin.

Conclusion

The kidney damage of HFD mice seems to be alleviated by emodin via the upregulation of GLP-1R in kidney tissue.

An Overview of the Posttranslational Modifications and Related Molecular Mechanisms in Diabetic Nephropathy

Diabetic nephropathy (DN), a common diabetic microvascular complication, is characterized by its complex pathogenesis, higher risk of mortality, and the lack of effective diagnosis and treatment methods. Many studies focus on the diagnosis and treatment of diabetes mellitus (DM) and have reported that the pathophysiology of DN is very complex, involving many molecules and abnormal cellular activities. Given the respective pivotal roles of NF-κB, Nrf2, and TGF-β in inflammation, oxidative stress, and fibrosis during DN, we first review the effect of posttranslational modifications on these vital molecules in DN. Then, we describe the relationship between these molecules and related abnormal cellular activities in DN. Finally, we discuss some potential directions for DN treatment and diagnosis. The information reviewed here may be significant in the design of further studies to identify valuable therapeutic targets for DN.

Pharmacology of apocynin: a natural acetophenone

Apocynin is a naturally occurring acetophenone, found in the roots of Apocynum cannabinum and Picrorhiza kurroa. Various chemical and pharmaceutical modifications have been carried out to enhance the absorption and duration of action of apocynin, like, formulation of chitosan-based apocynin-loaded solid lipid nanoparticles, chitosan-oligosaccharide based nanoparticles, and biodegradable polyanhydride nanoparticles. Apocynin has been subjected to a wide range of experimental screening and has proved to be useful for amelioration of a variety of disorders, like diabetic complications, neurodegeneration, cardiovascular disorders, lung cancer, hepatocellular cancer, pancreatic cancer, and pheochromocytoma. Apocynin has been primarily reported as an NADPH oxidase (NOX) inhibitor and prevents translocation of its p47^phox subunit to the plasma membrane, observed in neurodegeneration and hypertension. However, recent studies highlight its off-target effects that it is able to function as a scavenger of non-radical oxidant species, which is relevant for its activity against NOX 4 mediated production of hydrogen peroxide. Additionally, apocynin has shown inhibition of eNOS-dependent superoxide production in diabetic cardiomyopathy, reduction of NLRP3 activation and TGFβ/Smad signaling in diabetic nephropathy, diminished VEGF expression and decreased retinal NF-κB activation in diabetic retinopathy, inhibition of P38/MAPK/Caspase3 pathway in pheochromocytoma, inhibition of AKT-GSK3β and ERK1/2 pathways in pancreatic cancer, and decreased FAK/PI3K/Akt signaling in hepatocellular cancer. This review aims to discuss the pharmacokinetics and mechanisms of the pharmacological actions of apocynin.

Nuclear receptors in the kidney during health and disease

Over the last 30 years, nuclear receptors (NRs) have been increasingly recognized as key modulators of systemic homeostasis and as contributing factors in many diseases. In the kidney, NRs play numerous important roles in maintaining homeostasis-many of which continue to be unraveled. As "master regulators", these important transcription factors integrate and coordinate many renal processes such as circadian responses, lipid metabolism, fatty acid oxidation, glucose handling, and inflammatory responses. The use of recently-developed genetic tools and small molecule modulators have allowed for detailed studies of how renal NRs contribute to kidney homeostasis. Importantly, while NRs are intimately involved in proper kidney function, they are also implicated in a variety of renal diseases such as diabetes, acute kidney injury, and other conditions such as aging. In the last 10 years, our understanding of renal disease etiology and progression has been greatly shaped by knowledge regarding how NRs are dysregulated in these conditions. Importantly, NRs have also become attractive therapeutic targets for attenuation of renal diseases, and their modulation for this purpose has been the subject of intense investigation. Here, we review the role in health and disease of six key renal NRs including the peroxisome proliferator-activated receptors (PPAR), estrogen-related receptors (ERR), the farnesoid X receptors (FXR), estrogen receptors (ER), liver X receptors (LXR), and vitamin D receptors (VDR) with an emphasis on recent findings over the last decade. These NRs have generated a wealth of data over the last 10 years that demonstrate their crucial role in maintaining normal renal homeostasis as well as their capacity to modulate disease progression.

Renoprotective and haemodynamic effects of adiponectin and peroxisome proliferator-activated receptor agonist, pioglitazone, in renal vasculature of diabetic Spontaneously hypertensive rats

Pioglitazone, a therapeutic drug for diabetes, possesses full PPAR-γ agonist activity and increase circulating adiponectin plasma concentration. Plasma adiponectin concentration decreases in hypertensive patients with renal dysfunctions. Present study investigated the reno-protective, altered excretory functions and renal haemodynamic responses to adrenergic agonists and ANG II following separate and combined therapy with pioglitazone in diabetic model of hypertensive rats. Pioglitazone was given orally [10mg/kg/day] for 28 days and adiponectin intraperitoneally [2.5μg/kg/day] for last 7 days. Groups of SHR received either pioglitazone or adiponectin in combination. A group of Wistar Kyoto rats [WKY] served as normotensive controls, whereas streptozotocin administered SHRs served as diabetic hypertensive rats. Metabolic data and plasma samples were taken on day 0, 8, 21 and 28. In acute studies, the renal vasoconstrictor actions of Angiotensin II [ANGII], noradrenaline [NA], phenylephrine [PE] and methoxamine [ME] were determined. Diabetic SHRs control had a higher basal mean arterial blood pressure than the WKY, lower RCBP and plasma adiponectin, higher creatinine clearance and urinary sodium excretion compared to WKY [all P<0.05] which were normalized by the individual drug treatments and to greater degree following combined treatment. Responses to intra-renal administration of NA, PE, ME and ANGII were larger in diabetic SHR than WKY and SHRs [P<0.05]. Adiponectin significantly blunted responses to NA, PE, ME and ANG II in diabetic treated SHRs by 40%, whereas the pioglitazone combined therapy with adiponectin further attenuated the responses to adrenergic agonists by 65%. [all P <0.05]. These findings suggest that adiponectin possesses renoprotective effects and improves renal haemodynamics through adiponectin receptors and PPAR-γ in diabetic SHRs, suggesting that synergism exists between adiponectin and pioglitazone. A cross-talk relationship also supposed to exists between adiponectin receptors, PPAR-γ and alpha adrenoceptors in renal vasculature of diabetic SHRs.

MicroRNA‑199a‑3p suppresses high glucose‑induced apoptosis and inflammation by regulating the IKKβ/NF‑κB signaling pathway in renal tubular epithelial cells

Renal tubular epithelial cells (RTEC) injury induced by hyperglycemia is considered a major contributor to the pathogenesis of diabetic nephropathy (DN). However, few studies have focused on the role of microRNAs (miRNAs/miRs) in RTEC injury. Therefore, the present study aimed to investigate the role and mechanisms of miRNAs in RTEC injury. In the study, miRNAs expression profiles were determined via microarray assay in the peripheral blood samples of patients with DN. High glucose (HG)-induced injury in HK-2 cells was used as a cell model to examine the potential role of miR-199a-3p in DN. The expression of miR-199a-3p was validated using reverse transcription-quantitative PCR. The expressions of TNF-α, IL-1β and IL-6, were detected via ELISA. The protein levels of apoptosis-related proteins were determined using western blotting. Cell apoptosis and caspase 3 activity were evaluated via flow cytometry analysis and caspase 3 activity assay, respectively. Luciferase reporter assay was used to confirm the interaction between miR-199a-3p and IKKβ. miR-199a-3p was found to be significantly downregulated in the peripheral blood samples, and there was a negative correlation between miR-199a-3p expression and proteinuria in patients with DN. It was identified that miR-199a-3p expression was time-dependently decreased in the HG-induced cell damage model. Moreover, miR-199a-3p overexpression significantly improved HG-induced cell injury, as evidenced by the decrease in cell apoptosis and inflammation. Subsequent analyses demonstrated that miR-199a-3p directly targeted IKKβ, whose expression was increased, and negatively correlated with miR-199a-3p expression in patients with DN. The protective effects of miR-199a-3p overexpression on HG-treated HK-2 cells were partially reversed by IKKβ overexpression. In addition, activation of the NF-κB pathway by HG was blocked by miR-199a-3p mimics transfection in HK-2 cells. Collectively, the present findings indicated that miR-199a-3p protected HK-2 cells against HG-induced injury via inactivation of the IKKβ/NF-κB pathway, suggesting enhanced expression of miR-199a-3p as a potential therapeutic strategy for patients with DN.

Sauchinone Protects Renal Mesangial Cell Dysfunction against Angiotensin II by Improving Renal Fibrosis and Inflammation

Abnormal and excessive growth of mesangial cells is important in the pathophysiologic processes of diabetes-associated interstitial fibrosis and glomerulosclerosis, leading to diabetic nephropathy, which eventually turns into end-stage renal disease. Sauchinone, a biologically-active lignan isolated from aerial parts of Saururus chinensis, has anti-inflammatory and anti-viral activities effects on various cell types. However, there are no studies reporting the effects of sauchinone on diabetic nephropathy. The present study aims to investigate the role of sauchinone in mesangial cell proliferation and fibrosis induced by angiotensin II, as well as the underlying mechanisms of these processes. Human renal mesangial cells were induced by angiotensin II (AngII, 10 μM) in the presence or absence of sauchinone (0.1-1 μM) and incubated for 48 h. In this study, we found that AngII induced mesangial cell proliferation, while treatment with sauchinone inhibited the cell proliferation in a dose-dependent manner. Pre-treatment with sauchinone induced down-regulation of cyclins/CDKs and up-regulation of CDK inhibitor, p21, and p27kip1 expression. In addition, AngII-enhanced expression of fibrosis biomarkers such as fibronectin, collagen IV, and connective tissue growth factor (CTGF), which was markedly attenuated by sauchinone. Sauchinone also decreased AngII-induced TGF-β1 and Smad-2, Smad-3, and Smad-4 expression. This study further revealed that sauchinone ameliorated AngII-induced mesangial inflammation through disturbing activation of inflammatory factors, and NLRP3 inflammasome, which is composed of the NLRP3 protein, procaspase-1, and apoptosis-associated speck-like protein containing a CARD (ASC). Moreover, pretreatment of sauchinone inhibited NF-κB translocation and ROS production in AngII-exposed mesangial cells. These data suggest that sauchinone has a protective effect on renal proliferation, fibrosis and inflammation. Therefore, sauchinone might be a potential pharmacological agent in prevention of AngII-induced renal damage leading to diabetic nephropathy.

Targeting NLRP3 inflammasome as a promising approach for treatment of diabetic nephropathy: Preclinical evidences with therapeutic approaches

Diabetes mellitus is an increasingly prevalent disease around the globe. The epidemic of diabetes mellitus and its complications pretenses the foremost health threat globally. Diabetic nephropathy is the notable complication in diabetes, leading to end-stage renal disease (ESRD) and premature death. Abundant experimental evidence indicates that oxidative stress and inflammation are the important mediators in diabetic kidney diseases and interlinked with various signal transduction molecular mechanisms. Inflammasomes are the critical components of innate immunity and are recognized as a critical mediator of inflammation and autoimmune disorders. NOD-like receptor protein 3 (NLRP3) inflammasome is the well-characterized protein and it exhibits the sterile inflammation through the regulation of pro-inflammatory cytokines interleukin (IL)-1β and IL-18 production in tissues. In recent years, the role of NLRP3 inflammasome in the pathophysiology of diabetic kidney diseases in both clinical and experimental studies has generated great interest. In the current review, we focused on and discussed the role of NLRP3 inflammasome in diabetic nephropathy. A literature review was performed using online databases namely, PubMed, Scopus, Google Scholar and Web of science to explore the possible pharmacological interventions that blunt the NLRP3 inflammasome-caspase-1-IL-1β/IL-18 axis and shown to have a beneficial effect in diabetic kidney diseases. This review describes the inhibition of NLRP3 inflammasome activation as a promising therapeutic target for drug discovery in future.

Antidiabetic and antioxidant potential of Alnus nitida leaves in alloxan induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Leaves of Alnus nitida are used by local communities for the management of diabetes and in inflammatory disorders.

METHODS

Powder of shade dried leaves of A. nitida was extracted with methanol (ANME) and fractionated in escalating polarity i.e n-hexane (ANHE), chloroform (ANCE), ethyl acetate (ANEE) and soluble residual aqueous fraction (ANAE). The extract/fractions were evaluated for antidiabetic in vitro assays; α-amylase, α-glucosidase and dipeptidyl peptidase-4 (DPP-4). The in vivo investigations were carried out on ANEE and ANAE (100 mg/kg; 200 mg/kg, p.o.) in alloxan (125 mg/kg i.p.) induced hyperglycemic rats. Serum analysis was performed on liver, pancreas and kidney function markers. Analysis of antioxidant enzymes and genotoxic studies were carried out on pancreas, liver and kidneys tissues. GC-MS analysis was performed on ANME whereas HPLC analysis was carried out on ANME, ANEE and ANAE.

RESULTS

Preliminary in vitro assays indicated appreciable antidiabetic activity of ANEE and ANAE against α-amylase, α-glucosidase and DPP-4 assay. Furthermore, in vivo antidiabetic effect of ANEE and ANAE was inveterate by anti-hyperglycemic action in normal glucose loaded and diabetic glucose loaded animals. Single dose of alloxan (125 mg/kg) decreased the level of insulin and high density lipoprotein while raised the level of amylase and lipase, ALT, AST, total lipids, triglycerides, cholesterol, creatinine, BUN, CPK, CK-Mb in serum. Concentration of H₂O₂, lipid peroxidation (TBARS) and nitrite was increased (P < 0.05) whereas level of tissue protein, glutathione content (GSH) and antioxidant enzymes decreased in pancreas, liver and kidneys as compared to control group. Administration of ANEE and ANAE for 14 days after induction of diabetes decreased the hyperglycemia and restored the level of these parameters. Histopathological and genotoxic studies also endorsed the defensive strategies of ANEE and ANAE. GC-MS analysis of ANME demonstrated the presence of antidiabetic constituents i.e. linalool, Vitamin E and phytol.

CONCLUSION

Results obtained in this study suggests antidiabetic and antioxidant abilities and provides the scientific proof of the folklore medicine.

Inflammatory Targets in Diabetic Nephropathy

One of the most frequent complications in patients with diabetes mellitus is diabetic nephropathy (DN). At present, it constitutes the first cause of end stage renal disease, and the main cause of cardiovascular morbidity and mortality in these patients. Therefore, it is clear that new strategies are required to delay the development and the progression of this pathology. This new approach should look beyond the control of traditional risk factors such as hyperglycemia and hypertension. Currently, inflammation has been recognized as one of the underlying processes involved in the development and progression of kidney disease in the diabetic population. Understanding the cascade of signals and mechanisms that trigger this maladaptive immune response, which eventually leads to the development of DN, is crucial. This knowledge will allow the identification of new targets and facilitate the design of innovative therapeutic strategies. In this review, we focus on the pathogenesis of proinflammatory molecules and mechanisms related to the development and progression of DN, and discuss the potential utility of new strategies based on agents that target inflammation.

Amelioration of Lipopolysaccharide-Induced Nephrotic Proteinuria by NFAT5 Depletion Involves Suppressed NF-κB Activity

Idiopathic nephrotic syndrome (INS) is characterized by proteinuria, in which podocyte dysfunction associated with NF-κB-mediated inflammation plays an important role. The nuclear factor of activated T cells 5 (NFAT5) has been shown to enhance NF-κB activity. However, whether NFAT5 is associated with proteinuria remains uncharacterized. NFAT5 is upregulated in the glomeruli in lipopolysaccharide (LPS)-induced mouse nephrotic proteinuria, as well as in LPS-treated podocytes in vitro. In addition, NFAT5 depletion improves filtration barrier function of LPS-treated podocytes in vitro. Mechanistically, NFAT5 depletion suppresses NF-κB activation and downstream proinflammatory reaction in LPS-treated podocytes, and moreover, NF-κB inhibition improves filtration barrier function of LPS-treated podocytes, suggesting that the suppressed NF-κB activity at least partly accounts for NFAT5 depletion-improved filtration barrier function. Furthermore, in vivo, depletion of NFAT5 suppresses NF-κB activity and ameliorates nephrotic proteinuria in LPS-treated mice. These findings suggest a protective role of NFAT5 depletion against LPS-induced nephrotic proteinuria and relate it to the suppression of NF-κB activity.

Mechanisms of Herbal Nephroprotection in diabetes mellitus

Diabetic nephropathy (DN) is a leading cause of kidney morbidity. Despite the multilayered complexity of the mechanisms involved in the pathogenesis of DN, the conventional treatment is limited to just a few drug classes fraught with the risk of adverse events, including the progression of renal dysfunction. Phytoceuticals offer a promising alternative as they act on the many-sidedness of DN pathophysiology, multitargeting its intricacies. This paper offers a review of the mechanisms underlying the protective action of these phytoagents, including boosting the antioxidant capabilities, suppression of inflammation, averting the proliferative and sclerosing/fibrosing events. The pathogenesis of DN is viewed as a continuum going from the original offense, high glucose, through the noxious products it generates (advanced glycation end-products, products of oxidative and nitrosative stress) and the signaling chains consequently brought into action, to the harmful mediators of inflammation, sclerosis, and proliferation that eventually lead to DN, despite the countervailing attempts of the protective mechanisms. Special attention was given to the various pathways involved, pointing out the ability of the phytoagents to hinder the deleterious ones (especially those leading to, driven by, or associated with TGF-β activation, SREBP, Smad, MAPK, PKC, NF-κB, NLRP3 inflammasome, and caspase), to promote the protective ones (PPAR-α, PPAR-γ, EP4/Gs/AC/cAMP, Nrf2, AMPK, and SIRT1), and to favorably modulate those with potentially dual effect (PI3K/Akt). Many phytomedicines have emerged as potentially useful out of in vitro and in vivo studies, but the scarcity of human trials seriously undermines their usage in the current clinical practice-an issue that stringently needs to be addressed.

Pioglitazone attenuates kidney injury in an experimental model of gentamicin-induced nephrotoxicity in rats

Gentamicin, belonging to the aminoglycosides, possesses the greatest nephrotoxic effect of all other antibiotics from this group. On the other hand, pioglitazone, which represents peroxisome proliferator-activated receptor γ (PPARγ) agonist recently showed antiinflamatory, antioxidative effects, amelioration of endothelial dysfunction etc. Therefore, the goal of our study was to investigate the effects of pioglitazone on kidney injury in an experimental model of gentamicin-induced nephrotoxicity in rats. These effects were observed by following values of biochemical (serum urea and creatinine) parametars, total histological kidney score, urine level of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) as well as parametars of oxidative stress (malondialdehyde, superoxide dismutase, catalase, total oxidant status, total antioxidant status, oxidative stress index and advanced oxidation protein products). It seems that pioglitazone protects the injured rat kidney in a U-shaped manner. Medium dose of pioglitazone (1 mg/kg, i.p.) was protective regarding biochemical (serum urea and creatinine), total histological score and the values of kidney injury molecule-1 (KIM-1) (P < 0.05 vs. control group, i.e. rats injected with gentamicin only). This finding could be of great importance for the wider use of aminoglycosides, with therapy that would reduce the occurrence of serious adverse effects, such as nephrotoxicity and acute renal failure.

Zingerone (4-(4-hydroxy-3-methylphenyl)butan-2-one) ameliorates renal function via controlling oxidative burst and inflammation in experimental diabetic nephropathy

Development of diabetic nephropathy (DN) is directly linked to oxidative stress and inflammation. In this context, inflammatory and oxidative markers have gained much attention as targets for therapeutic intervention. We studied the effect of zingerone in a streptozotocin/high fat diet (STZ/HFD)-induced type 2 diabetic Wistar rat model. Zingerone also known as vanillyl acetone is a pharmacologically active compound present usually in dry ginger. STZ/HFD caused excessive increase in ROS and inflammation in experimental animals. The treatment with zingerone markedly abrogated ROS levels, inhibited the NF-кB activation and considerably reduced level of other downstream inflammatory molecules (TNF-α, IL-6, IL-1β), furthermore, zingerone treatment improved renal functioning by significantly decreasing the levels of kidney toxicity markers KIM-1, BUN, creatinine, and LDH and suppressed TGF-β. Collectively, these findings indicate that zingerone treatment improved renal function by anti-hyperglycaemic, anti-oxidant, and anti-inflammatory effects, suggesting the efficacy of zingerone in the treatment of DN.

MicroRNA as novel biomarkers and therapeutic targets in diabetic kidney disease: An update

Diabetic kidney disease (DKD) is a life-limiting condition characterized by progressive and irreversible loss of renal function. Currently, the estimated glomerular filtration rate (eGFR) and albuminuria are used as key markers to define DKD. However, they may not accurately indicate the degree of renal dysfunction and injury. Current therapeutic approaches for DKD, including attainment of blood pressure goals, optimal control of blood glucose and lipid levels, and the use of agents to block the renin-angiotensin-aldosterone system (RAAS) can only slow the progression of DKD. Hence, early diagnosis and innovative strategies are needed to both prevent and treat DKD. In recent years, a novel class of noncoding RNA, microRNAs (miRNAs) are reported to be involved in all biological processes, including cellular proliferation, apoptosis, and differentiation. miRNAs are small noncoding RNAs that regulate gene expression by posttranscriptional and epigenetic mechanisms. They are found to be in virtually all body fluids and used successfully as biomarkers for various diseases. Urinary miRNAs correlate with clinical and histologic parameters in DKD and differential urinary miRNA expression patterns have been reported. Kidney fibrosis is the common end stage of various CKD including DKD. Transforming growth factor-β(TGF-β) is regarded as the master regulator of kidney fibrosis, which is likely at least in part through regulating miRNA expression. miRNA are widely involved in the progression of DKD via many molecular mechanisms. In this review, the involvement of miRNA in fibrosis, inflammation, hypertrophy, autophagy, endoplasmic reticulum (ER) stress, oxidative stress, insulin resistance, and podocyte injury will be discussed, as these mechanisms are believed to offer new therapeutic targets that can be exploited to develop important treatments for DKD over the next decade.

A review of the anti-inflammatory properties of antidiabetic agents providing protective effects against vascular complications in diabetes

The global prevalence of Type 2 diabetes mellitus and its associated complications are growing rapidly. Although the role of hyperglycemia is well recognized in the pathophysiology of diabetic complications, its exact underlying mechanisms are not fully understood. In this regard, accumulating evidence suggests that the role of inflammation appears pivotal, with studies showing that most diabetic complications are associated with an inflammatory response. Several classes of antidiabetic agents have been introduced for controlling glycemia, with evidence that these pharmacological agents may have modulatory effects on inflammation beyond their glucose-lowering activity. Here we review the latest evidence on the anti-inflammatory effects of commonly used antidiabetic medications and discuss the relevance of these effects on preventing diabetic complications.

Carnosic acid improves diabetic nephropathy by activating Nrf2/ARE and inhibition of NF-κB pathway

BACKGROUND

Diabetic nephropathy (DN), one of the most serious complications of diabetes, is the leading cause of morbidity and mortality of end-stage renal disease. Our previous research found that carnosic acid (CA) or rosemary extract can effectively improve glucose and lipid metabolism disorder by inhibiting SREBPs.

PURPOSE

In this study, we aimed to explore the therapeutic effects of CA on the DN.

METHODS

The mice glomerular mesangial cells (mGMCs) were used to evaluate the anti-oxidative and anti-inflammation effects of CA under high glucose (HG) condition. Furthermore, db/db mice and streptozotocin (STZ)-induced diabetic mice were used to investigate the effects of CA against DN in vivo.

RESULTS

The results showed that CA activated Nrf2, inhibited NF-κB pathway and regulated related downstream genes in mGMC under HG condition. A 14-week treatment of mice with CA reduced water uptake and urine volume, attenuated diabetes-induced albuminuria, increased urine creatinine, and subsequently improved the glomerular sclerosis and mesangial expansion in db/db mice. Similarly, a 20-week oral administration of CA improved kidney damage in STZ-induced diabetic mice. In addition, CA inhibited the expression of profibrotic factors, such as TGF-β1, fibronectin and E-cadherin. Compared to irbesartan, CA exerted better glucose lowering effect, and in kidney, CA was more potent to reduce fibronectin and E-cadherin expression. In all the animal experiment, CA did not lead to abnormal damages to other tissues.

CONCLUSION

These findings suggest that CA is a safe compound which exerts the protective effects on diabetes-induced kidney complications.

Association of Elevated Urinary miR-126, miR-155, and miR-29b with Diabetic Kidney Disease

Effective diabetic kidney disease (DKD) biomarkers remain elusive, and urinary miRNAs represent a potential source of novel noninvasive disease sentinels. We profiled 754 miRNAs in pooled urine samples from DKD patients (n = 20), detecting significantly increased miR-126, miR-155, and miR-29b compared with controls (n = 20). These results were confirmed in an independent cohort of 89 DKD patients, 62 diabetic patients without DKD, and 41 controls: miR-126 (2.8-fold increase; P < 0.0001), miR-155 (1.8-fold increase; P < 0.001), and miR-29b (4.6-fold increase; P = 0.024). Combined receiver operating characteristic curve analysis resulted in an area under the curve of 0.8. A relative quantification threshold equivalent to 80% sensitivity for each miRNA gave a positive signal for 48% of DKD patients compared with 3.6% of diabetic patients without DKD. Laser-capture microdissection of renal biopsy specimens, followed by quantitative RT-PCR, detected miR-155 in glomeruli and proximal and distal tubules, whereas miR-126 and miR-29b were most abundant in glomerular extracts. Subsequent experiments showed miR-126 and miR-29b enrichment in glomerular endothelial cells (GEnCs) compared with podocytes, proximal tubular epithelial cells, and fibroblasts. Significantly increased miR-126 and miR-29b were detected in GEnC conditioned medium in response to tumor necrosis factor-α and transforming growth factor-β1, respectively. Our data reveal an altered urinary miRNA profile associated with DKD and link these variations to miRNA release from GEnCs.

G protein‑coupled estrogen receptor/miR‑148a/human leukocyte antigen‑G signaling pathway mediates cell apoptosis of ovarian endometriosis

The focus of the current study was a G protein‑coupled estrogen receptor (GPER)/microRNA (miR)‑148a/human leukocyte antigen‑G (HLA‑G) signaling pathway in ovarian endometriosis. Reverse transcription‑quantitative polymerase chain reaction was performed to analyze the changes in miR‑148a expression. A MTT assay, flow cytometry and caspase‑3/9 activity assays were performed to analyze cell proliferation, apoptosis and caspase‑3/9 activity levels, respectively. Protein expression was measured using western blot analysis. In tissue samples from healthy controls, and patients with endometriosis and endometriosis‑associated ovarian cancer, the expression of miR‑148a was lower in in endometriosis and EAOC samples compared with healthy controls. Overexpression of miR‑148a using miR mimics significantly decreased proliferation, promoted apoptosis, increased the Bcl‑2 associated X apoptosis regulator (Bax)/Bcl‑2 apoptosis regulator (Bcl‑2) ratio and caspase3/9 activity, and suppressed HLA‑G protein expression in Hs 832(C).T cells. miR‑148a downregulation using miR inhibitor significantly increased cell viability, inhibited apoptosis, and reduced the Bax/Bcl‑2 ratio and caspase3/9 activity, and induced HLA‑G protein expression in Hs 832(C).T cells. The GPER inhibitor, G15, suppressed GPER protein expression, upregulated miR‑148a expression, decreased cell proliferation, promoted apoptosis, increased the Bax/Bcl‑2 ratio and caspase3 activity, and suppressed HLA‑G protein expression in Hs 832(C).T cells. The findings indicate that GPER/miR‑148a/HLA‑G signaling pathway may mediates the development of ovarian endometriosis and may become a potential therapeutic target for the treatment of endometriosis.

Rapeseed protein-derived antioxidant peptide RAP alleviates renal fibrosis through MAPK/NF-κB signaling pathways in diabetic nephropathy

Introduction

Kidney fibrosis is the main pathologic change in diabetic nephropathy (DN), which is the major cause of end-stage renal disease. Current therapeutic strategies slow down but cannot reverse the progression of renal dysfunction in DN. Plant-derived bioactive peptides in foodstuffs are widely used in many fields because of their potential pharmaceutical and nutraceutical benefits. However, this type of peptide has not yet been studied in renal fibrosis of DN. Previous studies have indicated that the peptide YWDHNNPQIR (named RAP), a natural peptide derived from rapeseed protein, has an antioxidative stress effect. The oxidative stress is believed to be associated with DN. The aim of this study was to evaluate the pharmacologic effects of RAP against renal fibrosis of DN and high glucose (HG)-induced mesangial dysfunction.

Materials and methods

Diabetes was induced by streptozotocin and high-fat diet in C57BL/6 mice and these mice were treated by subcutaneous injection of different doses of RAP (0.1 mg/kg and 0.5 mg/kg, every other day) or PBS for 12 weeks. Later, functional and histopathologic analyses were performed. Parallel experiments verifying the molecular mechanism by which RAP alleviates DN were carried out in HG-induced mesangial cells (MCs).

Results

RAP improved the renal function indices, including 24-h albuminuria, triglyceride, serum creatinine, and blood urea nitrogen levels, but did not lower blood glucose levels in DN mice. RAP also simultaneously attenuated extracellular matrix accumulation in DN mice and HG-induced MCs. Furthermore, RAP reduced HG-induced cell proliferation, but it showed no toxicity in MCs. Additionally, RAP inhibited the mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signaling pathways.

Conclusion

RAP can attenuate fibrosis in vivo and in vitro by antagonizing the MAPK and NF-κB pathways.

Renoprotective Effect of Danhong Injection on Streptozotocin-Induced Diabetic Rats through a Peroxisome Proliferator-Activated Receptor γ Mediated Pathway

The aim of the study was to investigate the protective effect of Danhong injection (DHI) on diabetic kidney disease and explore the potential mechanisms. Diabetic kidney disease was induced by unilateral nephrectomy, high-fat diet, and streptozotocin. After DHI administration, the renal function deterioration, 24-hour total urine protein excretion, and elevated serum lipid levels were reversed to some extent, and the renal pathological damage was also ameliorated. The KEGG pathway enrichment analysis demonstrated that the PPARγ signal pathway was significantly upregulated in DH group. And the increased expressions of PPARγ and UCP-1 were confirmed by immunohistochemistry, whereas the p38MAPK was significantly decreased. These data show that DHI could delay the progress of DKD, and the effect might be achieved in part by activating the PPARγ signaling pathway.

1,25-Dihydroxyvitamin D3 protects obese rats from metabolic syndrome via promoting regulatory T cell-mediated resolution of inflammation

Vitamin D₃ has been found to produce therapeutic effects on obesity-associated insulin resistance and dyslipidemia through its potent anti-inflammatory activity, but the precise immunomodulatory mechanism remains poorly understood. In the present study we found that 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃], the biologically active form of vitamin D₃, significantly attenuated monosodium glutamate (MSG)-induced obesity and insulin resistance as indicated by body weight reduction, oral glucose tolerance improvement, and a glucose infusion rate increase as detected with hyperinsulinemic-euglycemic clamp. Moreover, 1,25(OH)₂D₃ not only restored pancreatic islet functions but also improved lipid metabolism in insulin-targeted tissues. The protective effects of 1,25(OH)₂D₃ on glycolipid metabolism were attributed to its ability to inhibit an obesity-activated inflammatory response in insulin secretory and targeted tissues, as indicated by reduced infiltration of macrophages in pancreas islets and adipose tissue while enhancing the expression of Tgf-β1 in liver tissue, which was accompanied by increased infiltration of Treg cells in immune organs such as spleen and lymph node as well as in insulin-targeted tissues such as liver, adipose, and muscle. Together, our findings suggest that 1,25(OH)₂D₃ serves as a beneficial immunomodulator for the prevention and treatment of obesity or metabolic syndrome through its anti-inflammatory effects.

NF-κβ: A Potential Target in the Management of Vascular Complications of Diabetes

Diabetes is a metabolic disorder affecting large percentage of population worldwide. NF-κβ plays key role in pathogenesis of vascular complications of diabetes. Persistent hyperglycemia activates NF-κβ that triggers expression of various cytokines, chemokines and cell adhesion molecules. Over-expression of TNF-α, interleukins, TGF-β, Bcl2 and other pro-inflammatory proteins and pro-apoptotic genes by NF-κβ is key risk factor in vascular dysfunction. NF-κβ over-expression also triggers calcification of endothelial cells leading to endothelial dysfunction and further vascular complications. Inhibition of NF-κβ pro-inflammatory pathway is upcoming novel target for management of vascular complications of diabetes. Various natural and synthetic inhibitors of NF-κβ have been studied in management of diabetic complications. Recent preclinical and clinical studies validate NF-κβ as promising target in the management of vascular complications of diabetes.

Peroxisome proliferator activating receptor-γ and the podocyte

Over the past two decades it has become clear that the glomerular podocyte is a key cell in preventing albuminuria, kidney failure and cardiovascular morbidity. Understanding the key pathways that protect the podocyte in times of glomerular stress, which can also be therapeutically manipulated, are highly attractive. In the following review we assess the evidence that the peroxisome proliferator activating receptor (PPAR) agonists are beneficial for podocyte and kidney function with a focus on PPAR-γ. We explain our current understanding of the mechanisms of action of these agonists and the evidence they are beneficial in diabetic and non-diabetic kidney disease. We also outline why these drugs have not been widely used for kidney disease in the past but they may be in the future.

Vinpocetine mitigates proteinuria and podocytes injury in a rat model of diabetic nephropathy

Podocyte injury and glomerular basement membrane thickening have been considered as essential pathophysiological events in diabetic nephropathy. The aim of this study was to investigate the possible beneficial effects of vinpocetine on diabetes-associated renal damage. Male Wistar rats were made diabetic by injection of streptozotocin (STZ). Diabetic rats were treated with vinpocetine in a dose of 20mg/kg/day for 6 weeks. Treatment with vinpocetine resulted in a marked decrease in the levels of blood glucose, glycosylated haemoglobin, creatinine, blood urea nitrogen, urinary albumin and albumin/creatinine ratio along with an elevation in creatinine clearance rate. The renal contents of advanced glycation end-products, interleukin-10, tissue growth factor-β, nuclear factor (NF)-κB and Ras-related C3 botulinum toxin substrate 1 (Rac 1) were decreased. Renal nephrin and podocin contents were increased and their mRNA expressions were replenished in vinpocetine-treated rats. Moreover, administration of vinpocetine showed improvements in oxidative status as well as renal glomerular and tubular structures. The current investigation revealed that vinpocetine ameliorated the STZ-induced renal damage. This beneficial effect could be attributed to its antioxidant and antihyperglycemic effects parallel to its ability to inhibit NF-κB which eventually modulated cytokines production as well as nephrin and podocin proteins expression.

Diabetic nephropathy: New insights into established therapeutic paradigms and novel molecular targets

Diabetic nephropathy is one of the most prevalent microvascular complication in patients suffering from diabetes and is reported to be the major cause of renal failure when compared to any other kidney disease. Currently, available therapies provide only symptomatic relief and unable to treat the underlying pathophysiology of diabetic nephropathy. This review will explore new insights into the established therapeutic paradigms targeting oxidative stress, inflammation and endoplasmic reticulum stress with the focus on recent clinical developments. Apart from this, the involvement of novel cellular and molecular mechanisms including the role of endothelin-receptor antagonists, Wnt signaling pathway, epigenetics and micro RNA is also discussed so that key molecular switches involved in the pathogenesis of diabetic nephropathy can be identified. Elucidating new molecular pathways will help in the development of novel therapeutics for the prevention and treatment of diabetic nephropathy.

Jiangtang decoction ameliorate diabetic nephropathy through the regulation of PI3K/Akt-mediated NF-κB pathways in KK-Ay mice

Background

Jiangtang decoction (JTD) is a China patented drug which contains Euphorbia humifusa Willd, Salvia miltiorrhiza Bunge, Astragalus mongholicus Bunge, Anemarrhena asphodeloides Bunge, and Coptis chinensis Franch. For decades, it has also been used clinically to treat diabetic nephropathy (DN) effectively; however, the associated mechanisms remain unknown. Thus, the present study aimed to examine the protective efficacy of JTD in DN and elucidate the underlying molecular mechanisms.

Methods

A diabetic model using KK-Ay mice received a daily administration of JTD for 12 weeks. Body weight, blood glucose, triglycerides (TGs), total cholesterol (TC), urea nitrogen (UN), creatinine (Cr), and microalbumin/urine creatinine (MA/UCREA) was measured every 4 weeks. Furthermore, on the day of the sacrifice, blood, urine, and kidneys were collected to assess renal function according to general parameters. Pathological staining was performed to evaluate the protective renal effect of JTD. In addition, the levels of inflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin [IL]-6 and intercellular adhesion molecule [ICAM]-1), insulin receptor substrate [IRS]-1, advanced glycation end products [AGEs], and receptor of glycation end products [RAGE] were assessed. Finally, the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway and involvement of nuclear factor-κB (NF-κB) was further analyzed.

Results

After 12 weeks of metformin and JTD administration, the mice exhibited a significant amelioration in glucose and lipid metabolism dysfunction, reduced morphological changes in the renal tissue, decreased urinary albumin excretion, and normalized creatinine clearance. JTD treatment also reduced the accumulation of AGEs and RAGE, up-regulated IRS-1, and increased the phosphorylation of both PI3K (p85) and Akt, indicating that the activation of the PI3K/Akt signaling pathway was involved. Additionally, JTD administration reduced the elevated levels of renal inflammatory mediators and decreased the phosphorylation of NF-κB p65.

Conclusions

These results demonstrate that JTD might reduce inflammation in DN through the PI3K/Akt and NF-κB signaling pathways.

Electronic supplementary material

The online version of this article (doi:10.1186/s13020-017-0134-0) contains supplementary material, which is available to authorized users.

Tangshen Formula Attenuates Colonic Structure Remodeling in Type 2 Diabetic Rats

Aim. This study investigated the effect and mechanism of the Chinese herbal medicine Tangshen Formula (TSF) on GI structure remodeling in the rat model of diabetes. Methods. Type 2 diabetic rats were used. Wet weight per unit length, layer thicknesses, levels of collagens I and III, nuclear factor kappa B (NF-κB), interferon-γ (IFN-γ), interleukin-6 (IL-6), transforming growth factor-β1 (TGF-β1), and Smad2/3 expression in the rat colon were measured. Results. Compared with the control group animals, wet weight and layer thicknesses of the colon increased, and expressions of collagens I and III, NF-κB, IFN-γ, IL-6, TGF-β1, and Smad2/3 increased significantly in the diabetic animals. TSF inhibited increase in colonic wet weight and layer thicknesses, downregulated expressions of collagens I and III in the mucosal layer, and downregulated expressions of NF-κB, IFN-γ, IL-6, TGF-β1, and Smad2/3 in the colon wall. Furthermore, level of expression of NF-κB was associated with those of TGF-β1 and Smad2/3. Expression of TGF-β1 was associated with the most histomorphometric parameters including colonic weight, mucosal and muscle thicknesses, and levels of collagens I and III in mucosal layer. Conclusion. TSF appears to attenuate colonic structure remodeling in type 2 diabetic rats through inhibiting the overactivated pathway of NF-κB, thus reducing expressions of TGF-β1.

Betanin, isolated from fruits of Opuntia elatior Mill attenuates renal fibrosis in diabetic rats through regulating oxidative stress and TGF-β pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The fruits of Opuntia elatior Mill are being used traditionally in different disease condition like diabetes, obesity, asthma, inflammatory disorders, and anemia. Betanin, a compound isolated from fruits of Opuntia elatior Mill has potent anti-oxidative and anti-inflammatory activity. Recent study from our lab indicated the protective effect of betanin against high glucose induced rat renal epithelial cell fibrosis and matrix accumulation, major features of diabetic nephropathy (DN). However the molecular mechanism of betanin in DN has not yet been fully elucidated.

AIM OF THE STUDY

The aim of the present study was to further investigate the anti-fibrotic mechanisms of betanin against streptozotocin (STZ) induced DN.

MATERIALS AND METHODS

Betanin was isolated from fruits of Opuntia elatior Mill (Cactaceae) and structure was elucidated using spectroscopy (UV, IR, 1H-NMR and mass). STZ was injected intraperitoneally with single dose of 50mg/kg for diabetes induction. In order to develop DN the animals were left in diabetes condition without any treatment during the following 4 weeks. Betanin (25, 50 and 100mg/kg/day) and lisinopril (5mg/kg/day, reference compound) were orally administered for 8 weeks after the induction of DN. Renal function, blood glucose, serum creatinine, blood urea nitrogen (BUN) and antioxidant enzyme activities in the kidney tissue were measured. Kidney tissue samples were used for glomerulosclerosis, tubulointerstitial fibrosis and morphometric studies. The expression of transforming growth factor-beta (TGF-β), type IV collagen, alpha-smooth muscle actin (α-SMA) and E-cadherin in kidney tissue were evaluated using reverse transcription-polymerase chain reaction, and immunohistochemistry.

RESULTS

Betanin was successfully isolated from fruits of Opuntia elatior Mill (Cactaceae) and purified by column chromatography. The results showed that betanin attenuated diabetic kidney injury by significantly inhibiting proteinuria, blood glucose, serum creatinine and BUN levels and restored antioxidant enzyme activities in kidney tissue. Histological studies exhibited that betanin treatment reduced the glomerular surface area, glomerulosclerosis and tubulointerstitial fibrosis. Furthermore, betanin modulated mRNA and protein expression of TGF-β, type IV collagen, α-SMA and E-cadherin in kidney.

CONCLUSIONS

The results conclude that betanin can effectively suppress renal fibrosis in DN, and may slow down the progression to end-stage renal disease by regulating TGF-β signal pathway.

Andrographolide ameliorates diabetic nephropathy by attenuating hyperglycemia-mediated renal oxidative stress and inflammation via Akt/NF-κB pathway

Diabetic nephropathy (DN) is characterized by proliferation of mesangial cells, mesangial hypertrophy and extracellular matrix (ECM) accumulation. Our recent study found that andrographolide inhibited high glucose-induced mesangial cell proliferation and fibronectin expression through inhibition of AP-1 pathway. However, whether andrographolide has reno-protective roles in DN has not been fully elucidated. Here, we studied the pharmacological effects of andrographolide against the progression of DN and high glucose-induced mesangial dysfunction. Diabetes was induced in C57BL/6 mice by intraperitoneal injection of streptozotocin (STZ). After 1 weeks after STZ injection, normal diet was substituted with a high-fat diet (HFD). Diabetic mice were intraperitoneal injected with andrographolide (2 mg/kg, twice a week). After 8 weeks, functional and histological analyses were carried out. Parallel experiments uncovering the molecular mechanism by which andrographolide prevents from DN was performed in mesangial cells. Andrographolide inhibited the increases in fasting blood glucose, triglyceride, kidney/body weight ratio, blood urea nitrogen, serum creatinine and 24-h albuminuria in diabetic mice. Andrographolide also prevented renal hypertrophy and ECM accumulation. Furthermore, andrographolide markedly attenuated NOX1 expression, ROS production and pro-inflammatory cytokines as well. Additionally, andrographolide inhibited Akt/NF-κB signaling pathway. These results demonstrate that andrographolide is protective against the progression of experimental DN by inhibiting renal oxidative stress, inflammation and fibrosis.

Geniposide reduces development of streptozotocin-induced diabetic nephropathy via regulating nuclear factor-kappa B signaling pathways

Renal pathology was a commonly seen complication in patients with diabetes. Geniposide (GPO) was previously demonstrated to modulate glucose metabolism in diabetes. This study was to investigate effects of GPO in streptozotocin-induced diabetic rats and its underlying mechanism. Renal function in diabetic rats was evaluated by levels of serum creatinine (Scr), blood urea nitrogen (BUN), and urinary albumin. Renal inflammation was appraised by inflammatory cells infiltration and pro-inflammatory cytokines production. Renal monocytes, T lymphocytes infiltration, and intercellular adhesion molecule-1 (ICAM-1) expression were quantitated by immunohistochemistry. Moreover, renal nuclear factor-kappa B (NF-κB) was assayed by Western blotting. Diabetic rats showed renal dysfunction as evidenced by increased levels of Scr, BUN, urinary albumin, and elevator renal index. Histological examination revealed significant glomerular basement membrane (GBM) thickening. However, GPO notably improved renal function and diabetes-induced GBM changes. Additionally, diabetic rats showed noteworthy renal inflammation,as reflected by enhancement of monocytes and T lymphocytes infiltration, increased expression of ICAM-1, tumor necrosis factor-α, interleukin-1 (IL-1), and IL-6. Interestingly, the level of monocytes infiltration positively correlated with the severity of GBM. Further study indicated diabetic rats displayed increased activation of NF-κB, indicated by increased expression of NF-κB p65, IKKα, and p-IκBα in renal tissue. However, all the changes in renal inflammation and NF-κB pathway were obviously reversed in GPO-treated diabetic rats. Our works indicate GPO ameliorates structural and functional abnormalities of kidney in diabetic rats, which is associated with its suppression of NF-κB-mediated inflammatory response.

Does Thiazolidinedione therapy exacerbate fluid retention in congestive heart failure?

The ever-growing global burden of congestive heart failure (CHF) and type 2 diabetes mellitus (T2DM) as well as their co-existence necessitate that anti-diabetic pharmacotherapy will modulate the cardiovascular risk inherent to T2DM while complying with the accompanying restrictions imposed by CHF. The thiazolidinedione (TZD) family of peroxisome proliferator-activated receptor γ (PPARγ) agonists initially provided a promising therapeutic option in T2DM owing to anti-diabetic efficacy combined with pleiotropic beneficial cardiovascular effects. However, the utility of TZDs in T2DM has declined in the past decade, largely due to concomitant adverse effects of fluid retention and edema formation attributed to salt-retaining effects of PPARγ activation on the nephron. Presumably, the latter effects are potentially deleterious in the context of pre-existing fluid retention in CHF. However, despite a considerable body of evidence on mechanisms responsible for TZD-induced fluid retention suggesting that this class of drugs is rightfully prohibited from use in CHF patients, there is a paucity of experimental and clinical studies that investigate the effects of TZDs on salt and water homeostasis in the CHF setting. In an attempt to elucidate whether TZDs actually exacerbate the pre-existing fluid retention in CHF, our review summarizes the pathophysiology of fluid retention in CHF. Moreover, we thoroughly review the available data on TZD-induced fluid retention and proposed mechanisms in animals and patients. Finally, we will present recent studies challenging the common notion that TZDs worsen renal salt and water retention in CHF.

Effects of combination PPARγ agonist and angiotensin receptor blocker on glomerulosclerosis

We previously observed that high-dose angiotensin receptor blocker (ARB) can induce regression of existing glomerulosclerosis. We also found that proliferator-activated recepto-γ (PPARγ) agonist can attenuate glomerulosclerosis in a nondiabetic model of kidney disease, with specific protection of podocytes. We now assessed effects of combination therapy with ARB and pioglitazone on established glomerulosclerosis. Sprague-Dawley male rats underwent 5/6 nephrectomy (5/6 Nx) at week 0 and renal biopsy at week 8. Rats were randomized to groups with equal starting moderate glomerulosclerosis, and treated with ARB, PPARγ agonist (pioglitazone), combination or vehicle from weeks 8 to 12. Body weight, systolic blood pressure (SBP), and urinary protein (UP) were measured at intervals. In rats with established sclerosis, SBP, UP, and GS were equal in all groups at week 8 before treatment by study design. Untreated control rats had hypertension, decreased GFR, and progressive proteinuria and glomerulosclerosis at week 12. Only combination therapy significantly ameliorated hypertension and proteinuria. ARB alone or pioglitazone alone had only numerically lower SBP and UP than vehicle at week 12. Both pioglitazone alone and combination had significantly less decline in GFR than vehicle. Combination-induced regression of glomerulosclerosis in more rats from weeks 8 to 12 than ARB or pioglitazone alone. In parallel, combination treatment reduced plasminogen activator inhibitor-1 expression and macrophage infiltration, and preserved podocytes compared with vehicle. These results were linked to increased AT2 receptor and Mas1 mRNA in the combination group. PPARγ agonists in combination with ARB augment regression of glomerulosclerosis, with downregulation of injurious RAAS components vs PPARγ alone, with increased anti-fibrotic/healing RAAS components, enhanced podocyte preservation, and decreased inflammation and profibrotic mechanisms.

High glucose induced-macrophage activation through TGF-β-activated kinase 1 signaling pathway

OBJECTIVE AND DESIGN

Transforming growth factor-β-activated kinase 1 (TAK1) plays a pivotal role in innate immune responses and kidney disease, and is critically involved in macrophage activation. However, there is a paucity of data to explore the role of high glucose (HG) in the regulation of TAK1 signaling and its functional role in macrophage activation. We assume that TAK1 signaling in hyperglycemic condition could be a key factor leading to macrophage activation and inflammation response.

METHODS

Mice macrophages were seeded on a 96-well cell culture plate; cell viability was tested after treatment with different concentration of TAK1 inhibitors. Cells were divided into groups (OZ300; MC; NC; HG; HG + OZ30, 100, 300 nM) and treated for given time course. Monocyte chemotactic protein1(MCP-1) and tumor necrosis factor-α (TNF-α) mRNA levels were evaluated by qRT-PCR. Flow cytometry and confocal microscopy are used to analyse the activated macrophage induced by HG. Expression levels of p-TAK1, TAB 1, p-JNK, p-p38MAPK, NF-κBpp65 were detected by western blot. Nuclear translocation of NF-κBp65 was assessed by confocal microscopy.

RESULTS

Our data revealed that high glucose not only significantly increased macrophage activation and subsequently abnormal high-expression of MCP-1 and TNF-α, but likewise remarkably enhanced TAK1 activation, MAPK phosphorylation, NF-κB expression in macrophages. Furthermore, pharmacological inhibition of TAK1 attenuated high glucose-triggered signal pathways, macrophage activation and inflammatory cytokines in a simulated diabetic environment.

CONCLUSION

Our findings suggested that high glucose activated macrophages mainly in TAK1/MAPKs and TAK1/NF-κB-dependent manners, which lead to the polarization of macrophages towards a pro-inflammatory phenotype, and finally lead to diabetic nephropathy. In sum, the study raises novel data about the molecular mechanisms involved in the high glucose-mediated inflammatory response in macrophages.

Osteomeles schwerinae extracts inhibits the binding to receptors of advanced glycation end products and TGF-β1 expression in mesangial cells under diabetic conditions

BACKGROUND

Osteomeles schwerinae C. K. Schneid. (Rosaceae, OSSC) is a medicinal plant traditionally used to treat various diseases in Asia. The chemical constituents of OSSC have an inhibitory effect on aldose reductase activity, which has been implicated in the pathogenesis of diabetic complications. However, the protective effects of the pharmacological activity and potential mechanisms in diabetic nephropathy are still not known.

OBJECTIVE

In the present study, OSSC extracts and major compounds were examined for their effects on binding to the receptors of advanced glycation end products (RAGE) and on transforming growth factor-beta1 (TGF-β1) expression-related signal mechanisms in mouse glomerular mesangial cells (GMCs).

MATERIALS AND METHODS

A simple, rapid and efficient method was developed for the simultaneous determination of the marker compounds in the ethanol extract of the leaves and twigs of OSSC using HPLC-diode array detector (DAD). In this study, we determined the effects of OSSC extract and hyperoside on AGE and RAGE binding, and studied the mechanism of OSSC extract effects on AGE-bovine serum albumin (BSA)-treated GMCs. GMCs overexpressing human RAGE were cultured in AGE-BSA labeled with Alexa 488, and OSSC extract. AGE/RAGE binding were measured using fluorescence (excitation 485 nm/emission 528 nm). TGF-β1 protein expression levels were determined by western blot analyses.

RESULTS

OSSC extracts of leaves and twigs inhibited on AGE/RAGE binding and TGF-β1 protein expression in a dose-dependent manner in GMCs. Furthermore, OSSC extracts reduced the effects on AGE-BSA-induced reactive oxidative species (ROS) formation and nuclear translocalization of transcription factor NF-κB. OSSC extracts inhibited phosphorylation of extracellular signal-regulated protein kinases1/2 (ERK1/2), p38 mitogen-activated protein kinases (p38MAPK), and IκB. Hyperoside also inhibited AGE/RAGE binding and ROS formation, and reduced TGF-β1 expression and IkB phosphorylation.

CONCLUSIONS

OSSC extracts and hyperoside may attenuate AGE/RAGE binding and expression of TGF-β1 by downregulating of pERK1/2, p38MAPK and IκB phosphorylations in GMCs under diabetic condition and retard the development of diabetic complications such as diabetic nephropathy.