Anti-fibrosis therapy and diabetic nephropathy

New anti-diabetic drug Morus alba L. (Sangzhi) alkaloids (SZ-A) improves diabetic nephropathy through ameliorating inflammation and fibrosis in diabetic rats

Background

Morus alba L. (Sangzhi) alkaloid (SZ-A) is a new antidiabetic drug approved by the China National Medical Products Administration in 2020. Diabetic nephropathy (DN) is a common diabetic complication and an important cause of morbidity and mortality in patients with diabetes. The effects of SZ-A on DN remain unknown.

Purpose

This study evaluated the effects of SZ-A on DN in Zucker diabetic fatty (ZDF) rats and explored the underlying mechanisms based on nitrosative stress, inflammation, and fibrosis.

Methods

Diabetic ZDF rats were orally administered 100 and 200 mg/kg of SZ-A once daily for 9 weeks. The glucose metabolism and kidney function were assayed. The pathological injury and fibrosis of the kidneys were separately evaluated using hematoxylin and eosin staining and Masson's staining. The oxidative and nitrosative stress and inflammation were assayed by determining the levels of related indices in the blood and kidneys and quantifying the related gene and protein expression. The expression of transforming growth factor β1 (TGFβ1) gene and protein were assayed by quantitative real-time PCR and immunohistochemistry, respectively. The renal transcriptomics was analyzed using RNA sequencing.

Results

Repeated treatment with SZ-A significantly improved glucose metabolism, dose-dependently decreased the levels of blood urea nitrogen, urinary albumin, and β2-microglobulin, and evidently relieved the renal injury in diabetic ZDF rats. As for the mechanisms, SZ-A remarkably ameliorated systemic nitrosative stress through lowering the levels of blood inducible nitric oxide synthase and nitric oxide, and significantly relieved systemic and renal inflammation by reducing the levels of blood interleukin-1β and monocyte chemoattractant protein-1 (MCP-1) and decreasing the levels of renal C-reactive protein content and expression of tumor necrosis factor-α in the kidneys. SZ-A also improved renal fibrosis by lowering the expression of TGFβ1 in the kidneys. Additionally, SZ-A significantly lowered the expression of stimulator of chondrogenesis 1 in the kidneys.

Conclusion

Repeated treatments with SZ-A significantly ameliorates DN by regulating systemic nitrosative stress, renal inflammation, and renal fibrosis partially through inhibition of the cytokine-NO and TGF-β1 signaling in ZDF rats, providing evidence for the additional application of SZ-A in clinical use for the treatment of DN.

Advances of berberine against metabolic syndrome-associated kidney disease: Regarding effect and mechanism

The prevalence of metabolic syndrome (MetS) is drastically growing worldwide, resulting in MetS-associated kidney disease. According to traditional theories, preventing blood pressure, lipid, glycose, and obesity and improving insulin resistance (IR), a couple of medications are required for MetS. It not only lowers patients' compliance but also elevates adverse reactions. Accordingly, we attempted to seek answers from complementary and alternative medicine. Ultimately, berberine (BBR) was chosen due to its efficacy and safety on MetS through multi-pathways and multi-targets. The effects and mechanisms of BBR on obesity, IR, diabetic nephropathy, hypertension, hyperlipidemia, and hyperuricemia were elaborated. In addition, the overall properties of BBR and interventions for various kidney diseases were also collected. However, more clinical trials are expected to further identify the beneficial effects of BBR.

Key Genetic Components of Fibrosis in Diabetic Nephropathy: An Updated Systematic Review and Meta-Analysis

Renal fibrosis (RF) constitutes the common end-point of all kinds of chronic kidney disease (CKD), regardless of the initial cause of disease. The aim of the present study was to identify the key players of fibrosis in the context of diabetic nephropathy (DN). A systematic review and meta-analysis of all available genetic association studies regarding the genes that are included in signaling pathways related to RF were performed. The evaluated studies were published in English and they were included in PubMed and the GWAS Catalog. After an extensive literature review and search of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, eight signaling pathways related to RF were selected and all available genetic association studies of these genes were meta-analyzed. ACE, AGT, EDN1, EPO, FLT4, GREM1, IL1B, IL6, IL10, IL12RB1, NOS3, TGFB1, IGF2/INS/TH cluster, and VEGFA were highlighted as the key genetic components driving the fibrosis process in DN. The present systematic review and meta-analysis indicate, as key players of fibrosis in DN, sixteen genes. However, the results should be interpreted with caution because the number of studies was relatively small.

Hemoglobin A1c and Angiographic Severity with Coronary Artery Disease: A Cross-Sectional Study

Background

Many studies have shown that glycated hemoglobin (HbA1c) is associated with coronary artery disease (CAD). HbA1c was independently related to angiographic severity in Chinese patients with CAD after adjusting for other covariates. Some traditional cardiovascular drugs may have an impact on this relationship.

Methods

This retrospective study enrolled a total of 572 CAD patients who underwent their coronary angiography and had their HbA1c levels measured at the Chinese Hospital. The complexity of the coronary artery lesions was evaluated using the Syntax score, and the subjects were divided into 4 inter quartiles according to HbA1c levels. Covariates included history of traditional cardiovascular drugs.

Results

The average age of selected participants was 61.00 ± 9.15 years old, and about 54.72% of them were male. Result of fully adjusted linear regression showed that HbA1c was positively associated with Syntax score after adjusting confounders (β = 1.09, 95% CI: 0.27, 1.91, P = 0.0096). By interaction and stratified analyses, the interactions were observed based on our specification including with the medication history of statins and angiotensin receptor blockers (ARBs) (P values for interaction <0.05).

Conclusion

In this study, we found a positive correlation between the HbA1c levels and the SYNTAX score among CAD individuals, and oral statins and ARBs medication could affect the correlation. Thus, HbA1c measurement could be used for the evaluation of the severity and complexity of coronary lesions among CAD patients.

Evaluation of renal fibrosis in various causes of glomerulonephritis by MR elastography: a clinicopathologic comparative analysis

BACKGROUND

Renal parenchymal fibrosis is the most important determinant of kidney disease progression and it is determined via biopsy. The aim of this study is to evaluate the renal stiffness noninvasively by magnetic resonance elastography (MRE) and to compare it with clinicopathologic parameters in glomerulonephritis and AA amyloidosis patients.

METHODS

Thirty-four patients with glomerular filtration rate (GFR) over 20 ml/min/1.73m² had non-contrast MRE prospectively. Kidney stiffness values were obtained from whole kidney, cortex, and medulla. Values were correlated with GFR, albuminuria, proteinuria, and degree of fibrosis that are assessed via renal biopsy. Patients were grouped clinicopathologically to assess the relation between stiffness and chronicity.

RESULTS

Mean whole kidney, cortex, and medulla stiffnesses were 3.78 (± 1.26), 3.63 (± 1.25), and 4.77 (± 2.03) kPa, respectively. Mean global glomerulosclerosis was 22% (± 18%) and median segmental glomerulosclerosis was 4% (min-max: 0%-100%). Extent of tubulointerstitial fibrosis was less than 25% in 26 of the patients (76.5%), 25%-50% in 6 of the patients (17.6%), and higher than 50% in 2 of the patients (5.9%). Fourteen patients were defined to have chronic renal parenchymal injury. MRE-derived stiffness values correlated negatively with parameters of fibrosis. Lower stiffness values were observed in patients with chronic renal injury compared to those without (P < 0.05 for whole kidney and medulla MRE-derived stiffness).

CONCLUSION

MRE-derived stiffness values were lower in patients with chronic injury. Stiffness decreases as glomerulosclerosis and tubulointerstitial fibrosis progresses in patients with primary glomerulonephritis and AA amyloidosis. With future studies, there may be a role for MRE to assess renal function in concert with conventional markers.

Efficacy of Tripterygium wilfordii Hook F on animal model of Diabetic Kidney Diseases: A systematic review and meta-analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Tripterygium wilfordii Hook F (TwHF) has been clinically applied in the treatment of Diabetic Kidney Diseases (DKD). A large number of animal experiments focused on the TwHF treatment of DKD were conducted every year, but the evidence for these preclinical studies is unclear.

AIM OF THE STUDY

This study aims to evaluate the efficacy of TwHF on diabetic nephropathy through a stematic reviews and meta-analysis of animal models, and whether it has an effect on improving kidney pathology, renal function indicators and blood sugar levels, it also summarizes the use of TwHF for treatment the underlying mechanism of DKD.

MATERIALS AND METHODS

We systematically searched studies from PubMed, Web of Science, Embase, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), and Wanfang database from inception to May 2020. Chinese studies from the list of Chinese Core Journals would be included. SYRCLE's risk of bias tool for animal studies was applied to assess the methodological quality of studies. A meta-analysis was performed by using RevMan 5.3.

RESULTS

Out of 429 records identified in the initial search, 32 studies were selected. The results indicated that, compared with control group, TwHF treatment improved 24 h urine protein (24 h-UP) level (SMD - 4.21, 95% CI - 5.38 to - 3.04, P < 0.001), serum creatinine (Scr) (MD - 14.97, 95% CI - 20.42 to - 9.53, P < 0.001), blood urea nitrogen (BUN) (MD - 4.07, 95% CI - 5.49 to - 2.66, P < 0.001), blood glucose (Glu) (MD - 2.40, 95% CI - 4.304 to - 0.49, P = 0.01), Triglyceride (TG) (MD - 1.57, 95% CI - 2.06 to - 1.08, P < 0.001), and Cholesterol (TC) (MD - 1.49, 95% CI - 2.23 to - 0.75 P < 0.001); and increased the level of albumin (Alb) (MD 3.40, 95% CI 1.69 to 5.11, P < 0.001) and weight (MD 30.89, 95% CI 24.35 to 37.42, P < 0.001). There were no statistical difference on Alanine aminotransferase (ALT) (MD 3.00, 95% CI - 7.80 to 13.81, P = 0.59) and Aspartate aminotransferase (AST) (MD 0.77, 95% CI -15.05 to 16.60, P = 0.92) after TwHF. Meta regression analysis showed that the DKD model induced by different methods (type I/II), the dose of Tripterygium wilfordii and the intervention time were not the reasons for the heterogeneity of 24 h-UP, Alb, Glu, Scr, and BUN (p > 0.05).

CONCLUSIONS

TwHF is an effective and safe to treat DKD, which can protect the kidneys through anti-inflammation, improving oxidative stress and podocyte damage, and inhibiting mesangial cell proliferation and extracellular matrix proliferation.

α-Lipoic Acid Increases Collagen Synthesis and Deposition in Nondiabetic and Diabetic Rat Kidneys

α-Lipoic acid (ALA) is widely used as a nutritional supplement and therapeutic agent in diabetes management. Well-established antioxidant and hypoglycemic effects of ALA were considered to be particularly important in combating diabetic complications including renal injury. The present study evaluated the potential of ALA to affect profibrotic events in kidney that could alter its structure and functioning. ALA was administered intraperitoneally (10 mg/kg) to nondiabetic and streptozotocin-induced diabetic male Wistar rats for 4 and 8 weeks. The effects of ALA were assessed starting from structural/morphological alterations through changes that characterize profibrotic processes, to regulation of collagen gene expression in kidney. Here, we demonstrated that ALA improved systemic glucose and urea level, reduced formation of renal advanced glycation end products (AGEs), and maintained renal structural integrity in diabetic rats. However, profibrotic events provoked in diabetes were not alleviated by ALA since collagen synthesis/deposition and expression of transforming growth factor-β1 (TGF-β1) and α-smooth muscle actin (α-SMA) remained elevated in ALA-treated diabetic rats, especially after 8 weeks of diabetes onset. Moreover, 8 weeks treatment of nondiabetic rats with ALA led to the development of profibrotic features reflected in increased collagen synthesis/deposition. Besides the TGF-β1 downstream signaling, the additional mechanism underlying the upregulation of collagen IV in nondiabetic rats treated with ALA involves decreased DNA methylation of its promoter that could arise from increased Tet1 expression. These findings emphasize the therapeutic caution in the use of ALA, especially in patients with renal diabetic complication.

Baicalin reversal of DNA hypermethylation-associated Klotho suppression ameliorates renal injury in type 1 diabetic mouse model

Baicalin is a flavone glycoside that possesses numerous pharmacological properties. but its protective mode of action in kidney injury induced by diabetes mellitus remains incompletely understood. Using a streptozotocin (STZ)-induced diabetic mouse model, we found that baicalin could ameliorate diabetes-induced the pathological changes of the kidney function and morphology through suppressing inflammation and oxidative stress. Furthermore, baicalin treatment could alleviate interstitial fibrosis in the diabetic kidney via inhibiting epithelial-to-mesenchymal transition (EMT), which was accompanied by a sharp upregulation of Klotho, the endogenous inhibitor of renal fibrosis. We further verified that baicalin-rescued expression of Klotho was associated with Klotho promoter hypomethylation due to aberrant methyltransferase 3a expressions. Klotho knockdown via RNA interferences largely abrogated the anti-renal fibrotic effects of Baicalin in HK2 cells. These findings suggested that baicalin could alleviate renal injury-induced by diabates through partly modulating Klotho promoter methylation, which provides new insights into the treatment of diabetic nephropathy.

The utility of magnetic resonance imaging for noninvasive evaluation of diabetic nephropathy

BACKGROUND

Noninvasive quantitative measurement of fibrosis in chronic kidney disease (CKD) would be desirable diagnostically and therapeutically but standard radiologic imaging is too variable for clinical usage. By applying a vibratory force, tissue shear wave stiffness can be measured by magnetic resonance elastography (MRE) that may correlate with progression of kidney fibrosis. Since decreased kidney perfusion decreases tissue turgor and stiffness, we combined newly available three-dimensional MRE shear stiffness measurements with MR arterial spin labeling (ASL) kidney blood flow rates to evaluate fibrosis in diabetic nephropathy.

METHODS

Thirty individuals with diabetes and Stage 0-5 CKD and 13 control individuals without CKD underwent noncontrast MRE with concurrent ASL blood flow measurements.

RESULTS

MRE cortical shear stiffness at 90 Hz was decreased significantly below controls in all CKD stages of diabetic nephropathy. Likewise, ASL blood flow decreased progressively from 480 ± 136 mL/min/100 g of cortical tissue in controls to 302 ± 95, 229 ± 7 and 152 ± 32 mL/min/100 g in Stages 3, 4 and 5 CKD, respectively. A magnetic resonance imaging (MRI) surrogate for the measured glomerular filtration fraction [surrogate filtration fraction = estimated glomerular filtration rate (eGFR)/ASL] decreased progressively from 0.21 ± 0.07 in controls to 0.16 ± 0.04 in Stage 3 and 0.10 ± 0.02 in Stage 4-5 CKD.

CONCLUSIONS

In this pilot study, MRI with ASL blood flow rates can noninvasively measure decreasing kidney cortical tissue perfusion and, with eGFR, a decreasing surrogate filtration fraction in worsening diabetic nephropathy that appears to correlate with increasing fibrosis. Differing from the liver, MRE shear stiffness surprisingly decreases with worsening CKD, likely related to decreased tissue turgor from lower blood flow rates.

WJ-39, an Aldose Reductase Inhibitor, Ameliorates Renal Lesions in Diabetic Nephropathy by Activating Nrf2 Signaling

Diabetic nephropathy (DN) is a chronic diabetic microvascular complication. Hyperactivity of the polyol pathway is involved in the pathogenesis of DN. Aldose reductase (AR), the rate-limiting enzyme of the polyol pathway, is expected to be an effective target in the treatment of DN. WJ-39 is a novel inhibitor of AR. The present study aimed at exploring the effects of WJ-39 in DN. DN was induced in rats by injecting 30 mg/kg streptozotocin (STZ). After 14 weeks, WJ-39 (10, 20, and 40 mg/kg) was intragastrically administered to the rats for 12 weeks. Treatment with WJ-39 significantly inhibited AR activation and ameliorated renal dysfunction and fibrosis in DN rats. WJ-39 reduced oxidative stress in the kidneys of DN rats by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. WJ-39 suppressed the activation of the nuclear factor-kappa B (NF-κB) pathway and the nucleotide-binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome to reduce the secretion of inflammatory factors. Rat mesangial cells (RMCs) were cultured under hyperglycemic conditions. WJ-39 abrogated the high glucose- (HG-) induced, excessive production of reactive oxygen species (ROS) and inflammatory factors. However, transfection with Nrf2 small interfering RNA abolished the effects of WJ-39. WJ-39 also blocked the transforming growth factor-β1/Smad pathway to reduce the production of glomerular extracellular matrix proteins, ultimately reducing fibrogenesis in DN. Our results show that WJ-39 ameliorated renal injury in DN rats, and its effects on oxidative stress and inflammation were associated with the activation of Nrf2 signaling. Thus, WJ-39 and its mechanism of amelioration of renal lesions in DN rats by reducing renal inflammation, oxidative stress, and fibrosis injury could be an effective strategy for the treatment of DN.

Complement C5a inhibition moderates lipid metabolism and reduces tubulointerstitial fibrosis in diabetic nephropathy

Background

Complement C5 mediates pro-inflammatory responses in many immune-related renal diseases. Given that the C5a level is elevated in diabetes, we investigated whether activation of C5a/C5aR signalling plays a pathogenic role in diabetic nephropathy (DN) and the therapeutic potential of C5a inhibition for renal fibrosis.

Methods

Human renal biopsies from patients with DN and control subjects were used for immunohistochemical staining of complement C5 components. Renal function and tubulointerstitial injury were compared between db/m mice, vehicle-treated mice and C5a inhibitor-treated db/db mice. A cell culture model of tubule epithelial cells (HK-2) was used to demonstrate the effect of C5a on the renal fibrotic pathway.

Results

Increased levels of C5a, but not of its receptor C5aR, were detected in renal tubules from patients with DN. The intensity of C5a staining was positively correlated with the progression of the disease. In db/db mice, administration of a novel C5a inhibitor, NOX-D21, reduced the serum triglyceride level and attenuated the upregulation of diacylglycerolacyltransferase-1 and sterol-regulatory element binding protein-1 expression and lipid accumulation in diabetic kidney. NOX-D21-treated diabetic mice also had reduced serum blood urea nitrogen and creatinine levels with less glomerular and tubulointerstitial damage. Renal transforming growth factor beta 1 (TGF-β1), fibronectin and collagen type I expressions were reduced by NOX-D21. In HK-2 cells, C5a stimulated TGF-β production through the activation of the PI3K/Akt signalling pathway.

Conclusions

Blockade of C5a signalling by NOX-D21 moderates altered lipid metabolism in diabetes and improved tubulointerstitial fibrosis by reduction of lipid accumulation and TGF-β-driven fibrosis in diabetic kidney.

PTEN-induced partial epithelial-mesenchymal transition drives diabetic kidney disease

Epithelial-mesenchymal transition (EMT) contributes significantly to interstitial matrix deposition in diabetic kidney disease (DKD). However, detection of EMT in kidney tissue is impracticable, and anti-EMT therapies have long been hindered. We reported that phosphatase and tensin homolog (PTEN) promoted transforming growth factor beta 1 (TGF-β), sonic hedgehog (SHH), connective tissue growth factor (CTGF), interleukin 6 (IL-6), and hyperglycemia-induced EMT when PTEN was modified by a MEX3C-catalyzed K27-linked polyubiquitination at lysine 80 (referred to as PTENK27-polyUb). Genetic inhibition of PTENK27-polyUb alleviated Col4a3 knockout-, folic acid-, and streptozotocin-induced (STZ-induced) kidney injury. Serum and urine PTENK27-polyUb concentrations were negatively correlated with glomerular filtration rate (GFR) for diabetic patients. Mechanistically, PTENK27-polyUb facilitated dephosphorylation and protein stabilization of TWIST, SNAI1, and YAP in renal epithelial cells, leading to enhanced EMT. We identified that a small molecule, triptolide, inhibited MEX3C-catalyzed PTENK27-polyUb and EMT of renal epithelial cells. Treatment with triptolide reduced TWIST, SNAI1, and YAP concurrently and improved kidney health in Col4a3 knockout-, folic acid-injured disease models and STZ-induced, BTBR ob/ob diabetic nephropathy models. Hence, we demonstrated the important role of PTENK27-polyUb in DKD and a promising therapeutic strategy that inhibited the progression of DKD.

RAAS inhibitors directly reduce diabetes-induced renal fibrosis via growth factor inhibition

KEY POINTS

Increased activation of the renin-angiotensin-aldosterone system (RAAS) and elevated growth factor production are of crucial importance in the development of renal fibrosis leading to diabetic kidney disease. The aim of this study was to provide evidence for the antifibrotic potential of RAAS inhibitor (RAASi) treatment and to explore the exact mechanism of this protective effect. We found that RAASi ameliorate diabetes-induced renal interstitial fibrosis and decrease profibrotic growth factor production. RAASi prevents fibrosis by acting directly on proximal tubular cells, and inhibits hyperglycaemia-induced growth factor production and thereby fibroblast activation. These results suggest a novel therapeutic indication and potential of RAASi in the treatment of renal fibrosis.

ABSTRACT

In diabetic kidney disease (DKD) increased activation of renin-angiotensin-aldosterone system (RAAS) contributes to renal fibrosis. Although RAAS inhibitors (RAASi) are the gold standard therapy in DKD, the mechanism of their antifibrotic effect is not yet clarified. Here we tested the antifibrotic and renoprotective action of RAASi in a rat model of streptozotocin-induced DKD. In vitro studies on proximal tubular cells and renal fibroblasts were also performed to further clarify the signal transduction pathways that are directly altered by hyperglycaemia. After 5 weeks of diabetes, male Wistar rats were treated for two more weeks per os with the RAASi ramipril, losartan, spironolactone or eplerenone. Proximal tubular cells were cultured in normal or high glucose (HG) medium and treated with RAASi. Platelet-derived growth factor (PDGF) or connective tissue growth factor (CTGF/CCN2)-induced renal fibroblasts were also treated with various RAASi. In diabetic rats, reduced renal function and interstitial fibrosis were ameliorated and elevated renal profibrotic factors (TGFβ1, PDGF, CTGF/CCN2, MMP2, TIMP1) and alpha-smooth muscle actin (αSMA) levels were decreased by RAASi. HG increased growth factor production of HK-2 cells, which in turn induced activation and αSMA production of fibroblasts. RAASi decreased tubular PDGF and CTGF expression and reduced production of extracellular matrix (ECM) components in fibroblasts. In proximal tubular cells, hyperglycaemia-induced growth factor production increased renal fibroblast transformation, contributing to the development of fibrosis. RAASi, even in non-antihypertensive doses, decreased the production of profibrotic factors and directly prevented fibroblast activation. All these findings suggest a novel therapeutic role for RAASi in the treatment of renal fibrosis.

Targeting heme oxygenase-1 in early diabetic nephropathy in streptozotocin-induced diabetic rats

Diabetic nephropathy (DN) is one of the most common microvascular diabetic complications. This study was designed to evaluate the possible protective effect and underlying mechanisms of HO-1 induction in streptozotocin (STZ)-induced early DN in rats. The diabetic rats were divided into three groups: STZ-diabetic, cobalt protoporphyrin (CoPP)-treated diabetic, and zinc protoporphyrin IX (ZnPP)-treated diabetic groups. Compared to the STZ-diabetic group, CoPP-induced HO-1 upregulation improved the diabetic state and renal functional parameters, suppressed the renal proinflammatory marker, NF-κB, abrogated the elevated renal hydroxyprolin, and decreased the enhanced renal nicotinamide adenine dinucleotide phosphate oxidase activity with parallel reduction of urinary oxidative stress markers. On the contrary, treatment with ZnPP abrogated HO-1 levels, aggravated the diabetic condition with further increases in renal oxidative stress, fibrotic and inflammatory markers, and exacerbated renal dysfunction in diabetic animals. These findings suggest that the reduced diabetic renal injury upon HO-1 induction implicates the role of HO-1 induction as a potential treatment for DN.

Relationship of angiotensin I-converting enzyme (ACE) and bradykinin B2 receptor (BDKRB2) polymorphism with diabetic nephropathy

PURPOSE

To determine whether ACE² I/D and BDKRB2³ +9/-9 polymorphism causatively affect diabetic nephropathy progression RESULTS: STZ-induced metabolic disorder, as well as inflammatory responses, was significantly aggravated in ACE II-B2R⁴+9bp, ACE DD-B2R+9bp, or ACE DD-B2R-9bp diabetic mice but not ACE II-B2R-9bp, indicating the genetic susceptibility of ACE DD or B2R+9bp to diabetic nephropathy. Furthermore, ACE II-B2R+9bp, ACE DD-B2R+9bp, or ACE DD-B2R-9bp rather than ACE II-B2R-9bp, worsened renal performance and enhanced pathological alterations induced by STZ. Markedly elevated monocyte chemoattractant protein-1(MCP-1), podocin, osteopontin (OPN), transforming growth factor-β1 (TGF-β1), and reduced nephrin, podocin were also detected both in diabetic mice and podocytes under hyperglycemic conditions in response to ACE II-B2R+9bp, ACE DD-B2R+9bp, or ACE DD-B2R-9bp, versus ACE II-B2R-9bp. In addition, high glucose-induced mitochondrial oxidative stress and cell apoptosis were observably increased in response to ACE II-B2R+9bp, ACE DD-B2R+9bp, or ACE DD-B2R-9bp but not ACE II-B2R-9bp.

CONCLUSIONS

We provide first evidence indicating the causation between ACE DD or B2R+9bp genotype and the increased risk for diabetic nephropathy, broadening our horizon about the role of genetic modulators in this disease.

Advances in Understanding and Management of Residual Renal Function in Patients with Chronic Kidney Disease

BACKGROUND

Residual renal function (RRF), defined as the ability of native kidneys to eliminate water and uremic toxins, is closely correlated with mortality and morbidity rates among patients receiving either peritoneal dialysis (PD) or hemodialysis (HD) via continuous clearance of middle-sized molecules and protein-bound solutes. Therefore, preserving RRF is considered to be one of the primary goals in managing patients with end-stage renal disease (ESRD).

SUMMARY AND KEY MESSAGES

In this article, we provide a review on the understanding and management of RRF in patients on dialysis. RRF may be estimated and measured by calculating the mean 24-hour urine creatinine level and urea clearance. Currently, several middle-sized molecules are reported but rarely used in practice. Many risk factors such as original renal diseases, dietary intake, and nephrotoxic agents impair RRF. Targeting such factors may halt the decline in RRF and offer better outcomes for patients on PD or HD. Except for in PD patients, RRF is a powerful predictor of survival in HD patients. RRF requires more clinical and research attention in the care of patients with ESRD on dialysis.

Semi-individualised Chinese medicine treatment as an adjuvant management for diabetic nephropathy: a pilot add-on, randomised, controlled, multicentre, open-label pragmatic clinical trial

INTRODUCTION

Diabetes mellitus and diabetic nephropathy (DN) are prevalent and costly to manage. DN is the leading cause of end-stage kidney disease. Conventional therapy blocking the renin-angiotensin system has only achieved limited effect in preserving renal function. Recent observational data show that the use of Chinese medicine (CM), a major form of traditional medicine used extensively in Asia, could reduce the risk of end-stage kidney disease. However, existing clinical practice guidelines are weakly evidence-based and the effect of CM remains unclear. This trial explores the effect of an existing integrative Chinese-Western medicine protocol for the management of DN.

OBJECTIVE

To optimise parameters and assess the feasibility for a subsequent phase III randomised controlled trial through preliminary evaluation on the effect of an adjuvant semi-individualised CM treatment protocol on patients with type 2 diabetes with stages 2-3 chronic kidney disease and macroalbuminuria.

METHODS AND ANALYSIS

This is an assessor-blind, add-on, randomised, controlled, parallel, multicentre, open-label pilot pragmatic clinical trial. 148 patients diagnosed with DN will be recruited and randomised 1:1 to a 48-week additional semi-individualised CM treatment programme or standard medical care. Primary end points are the changes in estimated glomerular filtration rate and spot urine albumin-to-creatinine ratio between baseline and treatment end point. Secondary end points include fasting blood glucose, glycated haemoglobin, brain natriuretic peptide, fasting insulin, C peptide, fibroblast growth factor 23, urinary monocyte chemotactic protein-1, cystatin C, nephrin, transforming growth factor-β1 and vascular endothelial growth factor. Adverse events are monitored through self-completed questionnaire and clinical visits. Outcomes will be analysed by regression models. Enrolment started in July 2015.

ETHICS AND REGISTRATION

This protocol is approved by the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (reference number UW 14-301).

TRIAL REGISTRATION NUMBER

NCT02488252.

A novel long non-coding RNA CYP4B1-PS1-001 regulates proliferation and fibrosis in diabetic nephropathy

Diabetic nephropathy is an important microvascular complication of diabetes, and the incidence of end-stage renal disease caused by it are rising annually. Long non-coding RNAs (lncRNAs) are widely regarded to associate with the occurrence and development of various diseases; however, the relationship between lncRNAs and diabetic nephropathy remains largely unknown. This work studied the effect of lncRNAs on diabetic nephropathy pathogenesis. LncRNA microarrays were initially used to detect lncRNAs with altered expression in three cases of kidney tissue from db/db mice with diabetic nephropathy. LncRNAs with differential expression (>2-fold) could be considered candidates. Particularly, CYP4B1-PS1-001 was significantly downregulated in response to early diabetic nephropathy in vitro and in vivo, while overexpression of CYP4B1-PS1-001 inhibited proliferation and fibrosis of mesangial cells. Overall, our data indicate the potential role of CYP4B1-PS1-001 in the proliferation and fibrosis of mice mesangial cells as the prominent features during early stage of diabetic nephropathy, which extend the relationship between lncRNAs and diabetic nephropathy, and may provide a potential therapeutic target and molecular biomarker for the disease.

Role and New Insights of Pirfenidone in Fibrotic Diseases

Pirfenidone (PFD) is a non-peptide synthetic molecule issued as a broad-spectrum anti-fibrotic drug with the ability to decrease TGF-β1, TNF-α, PDGF and COL1A1 expression, which is highly related to prevent or remove excessive deposition of scar tissue in several organs. Basic and clinical evidence suggests that PFD may safely slow or inhibit the progressive fibrosis swelling after tissue injuries. Furthermore, a number of evidence suggests that this molecule will have positive effects in the treatment of other inflammatory diseases. This review contains current research in which PFD has been used as the treatment of several diseases, and focus mainly in the outcomes related to improve inflammation and fibrogenesis. Therefore, the main goal of this review is to focus on the novel findings of PFD efficacy rather than deepen in the chemical aspects of the molecule.

Preserving residual renal function in dialysis: what we know

Residual renal function confers a survival benefit among dialysis patients thought to be related to greater volume removal and solute clearance. Whether the presence of residual renal function is protective or merely a marker for better health is not clear. The basic mechanisms governing the decline or persistence of residual renal function are poorly understood and few studies have examined the role of medical therapy in its preservation. Dialysis modality, inflammatory processes often associated with comorbid diseases (including diabetes mellitus and obesity), volume dysregulation, and vitamin D deficiency are predictive of residual renal function decline. We review potential mechanisms for preservation of remaining glomerular filtration rate among chronic dialysis patients.

Suppressor of cytokine signaling (SOCS) 2 attenuates renal lesions in rats with diabetic nephropathy

Diabetic nephropathy (DN) involves damage to the kidney caused by diabetes. It is characterized by renal hypertrophy, tubular atrophy/dilation and glomerular hyperfiltration. Suppressor of cytokine signaling (SOCS) 2 has recently been indicated to be involved in the pathogenesis of DN, however, the exact regulatory mechanisms remain unclear. This study was conducted to explore the role of SOCS2 in the development and progress of DN in a rat model of streptozocin (STZ)-induced diabetes. Recombinant adenoviruses expressing SOCS2 were used to upregulate the expression of SOCS2 in the kidneys of diabetic rats. Our results demonstrated that intrarenal injection of SOCS2 adenoviruses reduced STZ-induced renal lesions, including renal/glomerular hypertrophy, glomerular hyperfiltration, aberrant inflammation and fibrosis. Increased expression levels of proinflammatory proteins (monocyte chemoattractant protein-1, tumor necrotic factor-alpha and interleukin-6) and profibrotic proteins (transforming growth factor-beta, collagen IV and fibronectin) in the diabetic kidneys were decreased after SOCS2 gene delivery. Additionally, adenovirus-mediated upregulation of renal SOCS2 markedly inhibited STZ-induced phosphorylation increases of Janus kinase (JAK) 2, signal transducer and activator of transcription (STAT) 3, STAT5 and extracellular receptor-activated kinase (ERK) 1/2. In summary, the present research demonstrates that SOCS2 reduces renal lesions associated with diabetes in rats.

Diabetes and immunity to tuberculosis

The dual burden of tuberculosis (TB) and diabetes has attracted much attention in the past decade as diabetes prevalence has increased dramatically in countries already afflicted with a high burden of TB. The confluence of these two major diseases presents a serious threat to global public health; at the same time it also presents an opportunity to learn more about the key elements of human immunity to TB that may be relevant to the general population. Some effects of diabetes on innate and adaptive immunity that are potentially relevant to TB defense have been identified, but have yet to be verified in humans and are unlikely to fully explain the interaction of these two disease states. This review provides an update on the clinical and epidemiological features of TB in the diabetic population and relates them to recent advances in understanding the mechanistic basis of TB susceptibility and other complications of diabetes. Issues that merit further investigation - such as geographic host and pathogen differences in the diabetes/TB interaction, the role of hyperglycemia-induced epigenetic reprogramming in immune dysfunction, and the impact of diabetes on lung injury and fibrosis caused by TB - are highlighted in this review.

Influence of vanadium-organic ligands treatment on selected metal levels in kidneys of STZ rats

The objective of the study was to investigate the effects of five organic vanadium complexes supplement and a small dose of insulin injection on V, Fe, Cu, Zn, Mn, Ca, and K level in the streptozotocin diabetic rat's kidney during a 5-week treatment with the tested complexes. In all groups of animals, metal level in the lyophilized kidney organs was investigated by means of the proton induced X-ray emission method. Tissue vanadium level was naturally higher in vanadium-treated rats. The maximum level of vanadium was observed in the kidney (x(mean) = 16.6 μg/g). The influence of vanadium administration on other metal level in rat's tissue was also investigated. Spectacular influence of vanadium action was observed on copper and zinc level in examined tissue.

Korean red ginseng extract alleviates advanced glycation end product-mediated renal injury

The effect of Korean red ginseng (KRG) on diabetic renal damage was investigated using streptozotocin (STZ)-induced diabetic rats. The diabetic rats showed loss of body weight gain, and increases in kidney weight and urine volume, whereas the oral administration of KRG at a dose of 100 or 250 mg/kg of body weight per day for 28 d prevented these diabetes-induced physiological abnormalities. Among the kidney function parameters, elevated plasma levels of urea nitrogen and creatinine in diabetic control rats tended to be lowered in KRG-treated rats. In addition, administration of KRG at a dose of 100 mg/kg body weight in the diabetic rats showed significant decreases in serum glucose and tumor necrosis factor-α (TNF-α), implying that KRG might prevent the pathogenesis of diabetic complications caused by impaired glucose metabolism and oxidative stress. KRG also significantly reduced advanced glycation end product (AGE) formation and secretion from kidney of diabetic rats. Furthermore, KRG decreased the levels of N-(carboxymethyl) lysine and expression of AGE receptor. KRG also reduced the overexpression of cyclooxygenase-2 and inducible nitric oxide synthase in the kidney via deactivation of nuclear factor-kappa B. We also found that KRG prevented STZ-induced destruction of glomerular structure and significantly suppressed high glucose-induced fibronectin production. Taken together, KRG ameliorates abnormalities associated with diabetic nephropathy through suppression of inflammatory pathways activated by TNF-α and AGEs. These findings indicate that KRG has a beneficial effect on pathological conditions associated with diabetic nephropathy.

Pathogenesis and novel treatment from the mouse model of type 2 diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease worldwide. However, current treatments remain suboptimal. Many factors, such as genetic and nongenetic promoters, hypertension, hyperglycemia, the accumulation of advanced glycation end products (AGEs), dyslipidemia, and albuminuria/proteinuria itself, influence the progression of this disease. It is important to determine the molecular mechanisms and treatment of this disease. The development of diabetes results in the formation of AGEs, oxidative stress, and the activation of the renin-angiotensin-aldosterone system (RAAS) within the kidney, which promotes progressive inflammation and fibrosis, leading to DN and declining renal function. A number of novel therapies have also been tested in the experimental diabetic model, including exercise, inhibitors of the RAAS (angiotensin type 1 receptor blockers (ARB), angiotensin-converting enzyme (ACE) inhibitors), inhibitors of AGE (pyridoxamine), peroxisome proliferator-activated receptor (PPAR) γ agonists (pioglitazone), inhibitors of lipid accumulation (statins and eicosapentaenoic acid (EPA)), and the vitamin D analogues. This review summarizes the advances in knowledge gained from our studies and therapeutic interventions that may prevent this disease.