Role of angiotensin II in diabetic nephropathy

Intestinal Absorption of Nanoparticles to Reduce Oxidative Stress and Vasoconstriction for Treating Diabetic Nephropathy

The etiology of diabetic nephropathy (DN) is complex, and the incidence is increasing year by year. The patient's kidney showed oxidative stress damage, increasing active oxygen species (ROS) content, and vasoconstriction. Due to poor drug solubility and low renal accumulation, the current treatment regimens have not effectively alleviated glomerulopathy and other kidney damage caused by DN. Therefore, it is of great significance to explore new treatment strategies and drug delivery systems. Here, we constructed an oral nanodelivery system (Tel/CAN@CS-DA) that reduced oxidative stress and vasoconstriction. Deoxycholic acid (DA)-modified nanoparticles entered into intestinal epithelial cells (Caco2 cells) via the bile acid biomimetic pathway, then escaped from the lysosomes and eventually spat out the cells, increasing the oral absorption of nanoparticles. Chitosan (CS) nanoparticles could achieve renal targeting through specific binding with a renal giant protein receptor and deliver drugs to renal tubule epithelial cells (HK-2 cells). In vitro studies also proved that telmisartan (Tel) and canagliflozin (CAN) effectively removed cellular reactive oxygen species (ROS) and reduced HK-2 cell apoptosis caused by high glucose. In the in vivo model induced by streptozotocin (STZ), the results showed that the nanosystem not only elevated AMPK protein expression, inhibited angiotensin II (Ang II) protein expression to effectively reduce oxidative stress level, dilated renal blood vessels but also reduced the degree of inflammation and fibrosis. Overall, Tel/CAN@CS-DA multifunctional oral nanosystem can effectively treat DN with low toxicity, which provides a new idea for the treatment of DN.

Imperatorin ameliorates kidney injury in diabetic mice by regulating the TGF-β/Smad2/3 signaling axis, epithelial-to-mesenchymal transition, and renal inflammation

Diabetic nephropathy (DN) is a serious concern in patients with diabetes mellitus. Prolonged hyperglycemia induces oxidative damage, chronic inflammation, and build-up of extracellular matrix (ECM) components in the renal cells, leading to kidney structural and functional changes. Imperatorin (IMP) is a naturally occurring furanocoumarin derivative with proven antioxidative and anti-inflammatory properties. We investigated whether IMP could improve DN and employed high glucose (HG)-induced HK-2 cells and high-fat diet-fed streptozotocin (HFD/STZ)-generated DN experimental model in C57BL/6 mice. In vitro, IMP effectively reduced the HG-activated reactive oxygen species generation, disturbance in the mitochondrial membrane potential (MMP) and epithelial-to-mesenchymal transition (EMT)-related markers, and the transforming growth factor (TGF)-β and collagen 1 expression in HK-2 cells. In vivo, we found an elevation of serum creatinine, kidney histology alterations, and collagen build-up in the kidneys of the DN control group. Also, we found an altered expression of EMT-related markers, upregulation of the TGF-β/Smad2/3 axis, and elevated pro-inflammatory molecules, TNF-α, IL-1β, IL-18 and phospho-NF-kB (p65) in the DN control group. IMP treatment did not significantly reduce the blood glucose level compared to the DN control group. However, IMP treatment effectively improved renal damage by ameliorating kidney histological changes and serum renal injury markers. IMP treatment restored renal antioxidants and exhibited anti-inflammatory effects in the kidneys. Moreover, the abnormal manifestation of EMT-related attributes and elevated levels of TGF-β, phospho-Smad2/3, and collagen 1 were also normalized in the IMP treatment group. Our findings highlight that IMP may be a potential candidate for treating DN.

Chronic kidney disease in type 1 diabetes: translation of novel type 2 diabetes therapeutics to individuals with type 1 diabetes

Current management of chronic kidney disease (CKD) in type 1 diabetes centres on glycaemic control, renin-angiotensin system inhibition and optimisation of risk factors including blood pressure, lipids and body weight. While these therapeutic approaches have significantly improved outcomes among people with type 1 diabetes and CKD, this population remains at substantial elevated risk for adverse kidney and cardiovascular events, with limited improvements over the last few decades. The significant burden of CKD and CVD in type 1 diabetes populations highlights the need to identify novel therapies with the potential for heart and kidney protection. Over the last decade, sodium-glucose cotransporter-2 inhibitors, glucagon-like peptide 1 receptor agonists and non-steroidal mineralocorticoid receptor antagonists have emerged as potent kidney-protective and/or cardioprotective agents in type 2 diabetes. The consistent, substantial kidney and cardiovascular benefits of these agents has led to their incorporation into professional guidelines as foundational care for type 2 diabetes. Furthermore, introduction of these agents into clinical practice has been accompanied by a shift in the focus of diabetes care from a 'glucose-centric' to a 'cardiorenal risk-centric' approach. In this review, we evaluate the potential translation of novel type 2 diabetes therapeutics to individuals with type 1 diabetes with the lens of preventing the development and progression of CKD.

Candidate composite biomarker to inform drug treatments for diabetic kidney disease

Introduction

Current guidelines recommend renin angiotensin system inhibitors (RASi) as key components of treatment of diabetic kidney disease (DKD). Additional options include sodium-glucose cotransporter-2 inhibitors (SGLT2i), glucagon-like peptide 1 receptor agonists (GLP1a), and mineralocorticoid receptor antagonists (MCRa). The identification of the optimum drug combination for an individual is difficult because of the inter-, and longitudinal intra-individual heterogeneity of response to therapy.

Results

Using data from a large observational study (PROVALID), we identified a set of parameters that can be combined into a meaningful composite biomarker that appears to be able to identify which of the various treatment options is clinically beneficial for an individual. It uses machine-earning techniques to estimate under what conditions a treatment of RASi plus an additional treatment is different from the treatment with RASi alone. The measure of difference is the annual percent change (ΔeGFR) in the estimated glomerular filtration rate (ΔeGFR). The 1eGFR is estimated for both the RASi-alone treatment and the add-on treatment.

Discussion

Higher estimated increase of eGFR for add-on patients compared with RASi-alone patients indicates that prognosis may be improved with the add-on treatment. The personalized biomarker value thus identifies which patients may benefit from the additional treatment.

Identification of pyroptosis-related genes and potential drugs in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is one of the serious microvascular complications of diabetes mellitus (DM). A growing body of research has demonstrated that the inflammatory state plays a critical role in the incidence and development of DN. Pyroptosis is a new way of programmed cell death, which has the particularity of natural immune inflammation. The inhibition of inflammatory cytokine expression and regulation of pathways related to pyroptosis may be a novel strategy for DN treatment. The aim of this study is to identify pyroptosis-related genes and potential drugs for DN.

METHODS

DN differentially expressed pyroptosis-related genes were identified via bioinformatic analysis Gene Expression Omnibus (GEO) dataset GSE96804. Dataset GSE30528 and GSE142025 were downloaded to verify pyroptosis-related differentially expressed genes (DEGs). Least absolute shrinkage and selection operator (LASSO) regression analysis was used to construct a pyroptosis-related gene predictive model. A consensus clustering analysis was performed to identify pyroptosis-related DN subtypes. Subsequently, Gene Set Variation Analysis (GSVA), Gene Ontology (GO) function enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted to explore the differences between DN clusters. A protein-protein interaction (PPI) network was used to select hub genes and DGIdb database was utilized to screen potential therapeutic drugs/compounds targeting hub genes.

RESULTS

A total of 24 differentially expressed pyroptosis-related genes were identified in DN. A 16 gene predictive model was conducted via LASSO regression analysis. According to the expression level of these 16 genes, DN cases were divided into two subtypes, and the subtypes are mainly associated with inflammation, activation of immune response and cell metabolism. In addition, we identified 10 hub genes among these subtypes, and predicted 65 potential DN therapeutics that target key genes.

CONCLUSION

We identified two pyroptosis-related DN clusters and 65 potential therapeutical agents/compounds for DN, which might shed a light on the treatment of DN.

Ang-(1-7) attenuates podocyte injury induced by high glucose in vitro

Objective

The incidence of diabetic nephropathy (DN) is gradually increasing worldwide. Podocyte injury, such as podocyte apoptosis and loss of the slit diaphragm (SD)-specific markers are early pathogenic features of DN.

Materials and methods

The cultured mouse podocytes were separated into a high glucose-treated (HG, 30mM) group to mimic DN in vitro, a low glucose-treated (LG, 5mM) group as a control and HG+ angiotensin-(1-7)(Ang-(1-7)) and HG+Ang-(1-7) + D-Ala7-Ang-(1-7) (A779, Ang-(1-7)/Mas receptor antagonist) experimental groups. The Cell Counting Kit-8 (CCK-8) method and flow cytometry was used to detect podocyte activity and podocyte apoptosis respectively. The expression of angiotensin type 1 receptor (AT1R), Mas receptor (MasR) and podocyte-specific markers were examined by q-PCR and Western blot, respectively.

Results

The results showed that the decrease in podocyte activity; the increase in podocyte apoptosis; the decreased mRNA and protein expression of nephrin, podocin, WT-1 and MasR; and the upregulated expression of AT1R induced by HG could be reversed by Ang-(1-7). However, these effects were blocked by A779. The possible mechanisms of the Ang-(1-7)-mediated effect depended on MasR. In addition, the protective effect of Ang-(1-7) on podocyte activity was dose-dependent and most obvious at 10 µM. A779 had the greatest antagonistic action against Ang-(1-7) at a concentration of 10 μM.

Conclusion

This study reveals that binding of Ang-(1-7) to its specific receptor MasR may counteract the effects of Ang II mediated by AT1R to significantly attenuate podocyte injury induced by high glucose. Ang-(1-7)/MasR targeting in podocytes may be a therapeutic approach to attenuate renal injury in DN.

Progesterone levels associated with proteinuria in male diabetes mellitus patients: A cross-sectional retrospective study

INTRODUCTION

The relationship between progesterone (P) and diabetic nephropathy (DKD) is unclear. Herein, we investigated the relationship between progesterone and DKD in men and postmenopausal women with type 2 diabetes mellitus. MATERIALS AND METHODS: We recruited 3,556 male and postmenopausal female patients and obtained the dominance ratio (OR) and corresponding 95% confidence intervals (CIs) associated with progesterone by logistic regression analysis after adjusting for potentially confounding variants.

RESULTS

We found that progesterone levels were significantly lower in the massive proteinuria and microproteinuria groups compared with the non-DKD group for male patients. Also, microproteinuria and massive proteinuria prevalence were higher in the first (lowest) progesterone quartile than in the second to fourth quartiles. After adjusting for confounders, compared with the first (lowest) progesterone quartile group, the OR for the second to fourth quartiles in the male microproteinuria subgroup, were: Q2: 0.846 (95% CI: 0.581-1.233, P = 0.385); Q3: 0.667 (95% CI: 0.45-0988, P = 0.044); Q4: 0.597 (95% CI: 0.393-0.907, P = 0.016). In the male massive proteinuria subgroup, the OR for the third quartile group was 0.418 (95% CI: 0.201-0.867, P = 0.019). In contrast, no significant association was detected between progesterone and DKD prevalence in the female group.

CONCLUSIONS

Progesterone levels were negatively associated with DKD incidence in hospitalized male patients with type 2 diabetes mellitus.

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

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

Low plasma renin activity is independently associated with kidney disease progression in patients with type 2 diabetes and overt nephropathy, including those with impaired kidney function: a 2-year prospective study

Plasma renin activity (PRA) is lower in patients with diabetic nephropathy (DN) than in healthy individuals. However, the association, if any, between PRA and renal outcomes in patients with DN remains uncertain. In a 2-year prospective observational study, we aimed to investigate the association of PRA with the decline in kidney function in patients with DN. We studied 97 patients with DN who were categorized according to tertile (T1-T3) of PRA. The annual changes in estimated glomerular filtration rate (eGFR) (mL/min/1.73 m²/year) were determined from the slope of the linear regression curve for eGFR. The secondary endpoint was defined as a composite of the doubling of serum creatinine or end-stage renal disease. Results showed that kidney function rapidly declined with lower tertiles of PRA (median value [interquartile range] of the annual eGFR changes: -8.8 [-18.5 to -4.2] for T1, -8.0 [-14.3 to -3.2] for T2, and -3.1 [-6.3 to -2.0] for T3; p for trend <0.01). Multivariable linear regression analyses showed that, compared with T3, T1 was associated with a larger annual change in eGFR (coefficient, -4.410; 95% confidence interval [CI], -7.910 to -0.909 for T1). Composite renal events occurred in 46 participants. In multivariable Cox analysis, the lower tertiles of PRA (T1 and T2) were associated with higher incidences of the composite renal outcome (T2: hazard ratio [HR], 4.78; 95% CI, 1.64-13.89; T1: HR, 4.85; 95% CI 1.61-14.65) than T3. In conclusion, low PRA is independently associated with poor renal outcomes in patients with DN.

Involvement of Inflammasome Components in Kidney Disease

Inflammasomes are multiprotein complexes with an important role in the innate immune response. Canonical activation of inflammasomes results in caspase-1 activation and maturation of cytokines interleukin-1β and -18. These cytokines can elicit their effects through receptor activation, both locally within a certain tissue and systemically. Animal models of kidney diseases have shown inflammasome involvement in inflammation, pyroptosis and fibrosis. In particular, the inflammasome component nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) and related canonical mechanisms have been investigated. However, it has become increasingly clear that other inflammasome components are also of importance in kidney disease. Moreover, it is becoming obvious that the range of molecular interaction partners of inflammasome components in kidney diseases is wide. This review provides insights into these current areas of research, with special emphasis on the interaction of inflammasome components and redox signalling, endoplasmic reticulum stress, and mitochondrial function. We present our findings separately for acute kidney injury and chronic kidney disease. As we strictly divided the results into preclinical and clinical data, this review enables comparison of results from those complementary research specialities. However, it also reveals that knowledge gaps exist, especially in clinical acute kidney injury inflammasome research. Furthermore, patient comorbidities and treatments seem important drivers of inflammasome component alterations in human kidney disease.

Resistance exercise shifts the balance of renin-angiotensin system toward ACE2/Ang 1-7 axis and reduces inflammation in the kidney of diabetic rats

AIMS

We aimed to determine whether resistance training (RT) regulates renal renin-angiotensin system (RAS) components and inflammatory mediators in diabetic rats.

MAIN METHODS

Male Wistar rats (3 months old) were randomly assigned into four groups: non-trained (NT), trained (T), non-trained + diabetes (NTD) and trained +diabetes (TD). Diabetes was induced by streptozotocin (50 mg/kg, Sigma Chemical Co., St. Louis, MO, USA), before RT protocol. Trained rats performed RT protocol on a 110-cm ladder (8 ladder climbs, once/day, 5 days/week, 8 weeks), carrying a load corresponding to 50-80% of maximum carrying capacity. Blood glucose, albuminuria and urinary volume were measured. Renal levels of angiotensin peptides (angiotensin I, II and 1-7), inflammatory markers, and also the activities of angiotensin-converting enzyme (ACE) and ACE2 were determined.

KEY FINDINGS

Blood glucose and urinary volume were elevated in diabetic animals, and RT decreased albuminuria, renal Ang I and Ang II levels in diabetic rats. RT shifted the balance of renal RAS toward ACE2/Ang 1-7 axis in TD group, and mitigated the high levels of interleukin (IL)-10, IL-1β and cytokine-induced neutrophil chemoattractant 1 (CINC) in the context of diabetes. Strong positive correlations were found between albuminuria and Ang II, IL-10 and IL-1β. On the other hand, intrarenal Ang 1-7 levels were negatively correlated with IL-10 and IL-1β levels.

SIGNIFICANCE

RT improved kidney function by modulating intrarenal RAS toward ACE2/Ang 1-7 axis and inflammatory cytokines. RT represents a reasonable strategy to improve the renal complications induced by diabetes, counteracting nephropathy-associated maladaptive responses.

Renoprotective mechanisms of sodium-glucose co-transporter 2 (SGLT2) inhibitors against the progression of diabetic kidney disease

Sodium-glucose co-transporter 2 inhibitors (SGLT2-Is) have emerged as a promising class of antidiabetic drugs with cardioprotective and renoprotective effects in patients with type 2 diabetes (T2D). The sodium-glucose co-transporters 1 and 2 (SGLT 1 and SGLT2) located in the renal proximal tubules are responsible for glucose reabsorption from the glomerular filtrate back into the systemic circulation. Inhibition of SGLT2, which accounts for about 90% of the glucose reabsorption, leads to a significant reduction in blood glucose levels and a concomitant increase in the urinary excretion of glucose (glycosuria). Multiple mechanisms contribute to the nephroprotective effects of SGLT2-Is in T2D patients. These include: (1) Restoration of the tubuloglomerular feedback by increasing sodium delivery at macula densa, leading to afferent arteriolar constriction and reduced glomerular hyperfiltration, (2) Decreased activation of the intra-renal renin-angiotensin-aldosterone system, which also contributes to reducing glomerular hyperfiltration, (3) Increased production of ketone bodies, which serves as an alternate fuel for adenosine triphosphate production in mitochondria, which helps in attenuating inflammation, and (4) Protection against hypoxia, oxidative stress, and fibrosis. This review elaborates on the key mechanisms that underlie the nephroprotective effects and the adverse effects of SGLT2-Is in T2D patients with progressive diabetic kidney disease.

Proteomic Biomarkers in the Cardiorenal Syndrome: Toward Deciphering Molecular Pathophysiology

Cardiorenal syndrome (CRS) is defined by coexisting heart and renal dysfunctions. Malfunction of 1 organ may cause dysfunction of the other with variable causative disease that defines the type of CRS (1-5). Numerous studies showed that the prevalence of cardiovascular disease is increased in patients with chronic kidney disease (CKD). Similarly, CKD affects a large proportion of patients with heart failure. This overlap between primary heart or primary kidney disease blurs cause-effect inferences of the initiator/target organ. The classical subdivision of CRS in 5 categories does not provide pathophysiological suggestions for targeted intervention. It seems timely to revisit the value of CRS biomarkers in a pathophysiology-centered approach. We systematically reviewed the literature in CRS, which revealed 53 clinical studies describing the use of 44 biomarkers and 4 proteomic panels. All biomarkers are involved in at least one of the CRS comorbidities. Among the pathways affected, inflammation, aberrant glucose metabolism, neurohormonal activation, and oxidative stress are well described. There is growing evidence that fibrosis may be the "cornerstone" that unifies most of the pathways leading to CRS. Formation of excess fibrous connective tissue antedates CRS in many cases. This review highlights that biomarkers reflecting fibrosis may be of substantial clinical value in the early detection, prognostication, and guiding treatment of CRS. Biomarkers detecting changes in collagen turnover in the extracellular matrix of heart and kidney appear able to depict subclinical changes in the fibrotic remodeling of tissues and constitute a promising approach toward personalized intervention in CRS.

SH3YL1 protein as a novel biomarker for diabetic nephropathy in type 2 diabetes mellitus

BACKGROUND AND AIMS

Oxidative stress contributes to development of diabetic nephropathy. We implicated SH3YL1 in oxidative stress-induced inflammation and examined whether SH3YL1 could be used as a new biomarker of diabetic nephropathy.

METHODS AND RESULTS

In this study, we investigated the relationship between plasma level of SH3YL1 and diabetic nephropathy in patients with type 2 diabetes. In addition, we examined the physiological role of SH3YL1 in db/db mice and cultured podocytes. Plasma SH3YL1 concentration was significantly higher in patients with diabetes than in controls, even in normoalbuminuric patients, and was markedly increased in the macroalbuminuria group. Plasma SH3YL1 level was positively correlated with systolic blood pressure, HOMA-IR, postprandial blood glucose, plasma level of retinol binding protein 4 (RBP 4), and urinary albumin excretion (UAE) and was inversely correlated with BMI. Regression analysis showed that plasma level of RBP 4, UAE, and BMI were the only independent determinants of plasma SH3YL1 concentration. In db/db mice, plasma and renal SH3YL1 levels were significantly increased in mice with diabetes compared with control mice. In cultured podocytes, high glucose and angiotensin II stimuli markedly increased SH3YL1 synthesis.

CONCLUSION

These findings suggest that plasma level of SH3YL1 offers a promising new biomarker for diabetic nephropathy.

Knockout of NGAL aggravates tubulointerstitial injury in a mouse model of diabetic nephropathy by enhancing oxidative stress and fibrosis

Neutrophil gelatinase-associated lipocalin (NGAL), also called lipocalin 2, is considered a promising biomarker for acute and chronic kidney injuries. Several studies have demonstrated that its levels increase in plasma and urine in diabetic nephropathy (DN), and its urine concentration increases upon kidney function deterioration. However, its role in DN progression remains unclear. The current study used in vitro gene expression knockdown in human proximal tubular cell line human kidney (HK)2 to investigate the role of NGAL in oxidation and extracellular matrix secretion under high-glucose (HG) incubation. In addition, type 1 diabetes was induced in vivo in knockout NGAL^-/- and wild-type mice in order to investigate role of NGAL in the progression of DN. The results demonstrated that NGAL knockdown in HK2 cells significantly increased oxidative stress under HG stimulation tested by flow cytometry, and increased the secretion of interleukin-6, fibronectin (FN) and collagen IV examined by ELISA. Western blotting demonstrated that the phosphorylation of Smad2/3 also increased in HK2 cells under transforming growth factor-β1 stimulation. In vivo experiments demonstrated that diabetic NGAL^-/- mice showed deteriorated renal function compared with that of diabetic wild-type mice. Histopathological analysis suggests that diabetic NGAL^-/- mice had more serious glomerulosclerosis and tubular vascular degeneration than wild-type mice. Immunohistochemistry suggested that the absence of NGAL lead to increased FN deposition in glomeruli in a mouse model of DN. In conclusion, NGAL appears to have renal protective effects by slowing down the progression of DN, and its effect may be associated with a reduction in oxidation, fibrosis and inflammation.

Fractional excretion of magnesium as an early indicator of renal tubular damage in normotensive diabetic nephropathy

Objectives

The aim of the present study is to evaluate the diagnostic powers of fractional magnesium, sodium and potassium as markers of renal tubular damage in normotensive type 2 diabetes mellitus (T2DM) patients with respect to microalbuminuria and estimated glomerular filtration rate (eGFR).

Materials and methods

Forty healthy volunteers and 91 normotensive T2DM patients were included in the study. Patient group was divided into two according to albuminuria level; 49 were normoalbuminuric and 42 were microalbuminuric. In addition to albumin in urine, urine and serum Na, K, Mg and creatinine values were measured to calculate fractional electrolyte excretion rates.

Results

In normoalbuminuric and microalbuminuric groups, fractional excretion of magnesium (FEMg) values were found to be significantly higher than the control group (p < 0.05). There was a moderate correlation between FEMg and albümin to cratinin ratio (ACR) (Spearman r = 0.3215, p < 0.05). In the ROC analysis for eGFR and FEMg based on microalbuminuria, the areas under the curve were 0.625 and 0.732, respectively (diagnostic sensitivity 59.52% and 66.67%; specificity 70.79% and 77.53%, p < 0.05).

Conclusion

For renal tubular damage predicted by microalbuminuria, FEMg could be accepted as a candidate biochemical marker with diagnostic and prognostic value.

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.

Kidney-targeted astaxanthin natural antioxidant nanosystem for diabetic nephropathy therapy

Diabetic nephropathy (DN) is a frequent and severe microvascular complication associated with oxidative stress of diabetes mellitus. A novel astaxanthin-based natural antioxidant nanosystem, namely AST-GLU-LIP, with preferential renal uptake and bioavailability were prepared and applied for treatment of diabetic nephropathy in rats. Our results of kidney-targeted evaluation showed that glucose-PEG₆₀₀-DSPE ligand modified AST liposomes could be specifically transported by overexpressed GLUT1 on the membrane of glomerular mesangial cells and achieved excellent kidney-targeted drug delivery. In addition, the results of pharmacodynamics and therapeutics in DN rats demonstrated that AST-GLU-LIP could improve the bioavailability and antioxidant capacity of AST to scavenge redundant ROS induced by oxidative stress. AST-GLU-LIP could also significantly improve the renal pathological morphology to protect the kidney as a therapeutic drug for diabetic nephropathy.

Liver Stiffness Is Associated With Progression of Albuminuria in Adults With Type 2 Diabetes: Nonalcoholic Fatty Disease Cohort Study

OBJECTIVES

Previous studies have shown the association between liver fibrosis and albuminuria. However, the effect of liver fibrosis on change in albuminuria is unclear. Thus, we investigated the effect of liver fibrosis on change in albuminuria in patients with type 2 diabetes.

METHODS

In this retrospective cohort study, we assessed 105 patients with type 2 diabetes concomitant with nonalcoholic fatty disease. A change in urinary albumin excretion (UAE) was defined as follows: change in UAE=(logarithm [UAE+1] at follow-up examination minus logarithm [UAE+1] at baseline examination) / follow-up duration (1 year in this study). Elastography was performed to assess controlled attenuation parameter (dB/m) and liver stiffness measurement (LSM; kPa) values.

RESULTS

Mean (standard deviation) data were as follows: age, 63.3 (12.1) years; body mass index, 25.4 (4.3) kg/m²; controlled attenuation parameter, 273.1 (53.0) dB/m; and LSM, 6.2 (3.4) kPa. Median UAE value (interquartile range) was 16 (6 to 43) mg/g creatinine. LSM was associated with changes in UAE (r=0.27, p=0.005). Multiple regression analysis demonstrated that LSM was associated with change in UAE (β=0.28, p=0.015) after adjusting for sex, age, duration of diabetes, smoking status, exercise habits, glycated hemoglobin, body mass index, estimated glomerular filtration rate, systolic blood pressure, logarithm (UAE+1) at baseline examination, use of renin‒angiotensin system inhibitors, new use of sodium glucose cotransporter-2 inhibitors and glucagon-like peptide-1 and controlled attenuation parameter.

CONCLUSIONS

Liver stiffness is an independent risk factor for the progression of albuminuria in patients with type 2 diabetes.

The Interplay of Renin-Angiotensin System and Toll-Like Receptor 4 in the Inflammation of Diabetic Nephropathy

Diabetic nephropathy (DN) is one of the most serious chronic kidney diseases and the major cause of end-stage renal failure worldwide. The underlying mechanisms of DN are complex and required to be further investigated. Both innate immunity and renin-angiotensin system (RAS) play critical roles in the pathogenesis of DN. Except for traditional functions, abnormally regulated RAS has been proved to be involved in the inflammatory process of DN. Toll-like receptor 4 (TLR4) is the most deeply studied pattern recognition receptor in the innate immune system, and its activation has been reported to mediate the development of DN. In this review, we aim at discussing how dysregulated RAS affects TLR4 activation in the kidney that contributes to the exploration of the pathogenesis of DN. Understanding the interplay of RAS and TLR4 in inducing the progression of DN may provide new insights to develop effective treatments.

VSMC-Specific Deletion of FAM3A Attenuated Ang II-Promoted Hypertension and Cardiovascular Hypertrophy

RATIONALE

Dysregulated purinergic signaling transduction plays important roles in the pathogenesis of cardiovascular diseases. However, the role and mechanism of vascular smooth muscle cell (VSMC)-released ATP in the regulation of blood pressure, and the pathogenesis of hypertension remain unknown. FAM3A (family with sequence similarity 3 member A) is a new mitochondrial protein that enhances ATP production and release. High expression of FAM3A in VSMC suggests it may play a role in regulating vascular constriction and blood pressure.

OBJECTIVE

To determine the role and mechanism of FAM3A-ATP signaling pathway in VSMCs in the regulation of blood pressure and the pathogenesis of hypertension.

METHODS AND RESULTS

In the media layer of hypertensive rat and mouse arteries, and the internal mammary artery of hypertensive patients, FAM3A expression was increased. VSMC-specific deletion of FAM3A reduced vessel contractility and blood pressure levels in mice. Moreover, deletion of FAM3A in VSMC attenuated Ang II (angiotensin II)-induced vascular constriction and remodeling, hypertension, and cardiac hypertrophy in mice. In cultured VSMCs, Ang II activated HSF1 (heat shock factor 1) to stimulate FAM3A expression, activating ATP-P2 receptor pathway to promote the change of VSMCs from contractile phenotype to proliferative phenotype. In the VSMC layer of spontaneously hypertensive rat arteries, Ang II-induced hypertensive mouse arteries and the internal mammary artery of hypertensive patients, HSF1 expression was increased. Treatment with HSF1 inhibitor reduced artery contractility and ameliorated hypertension of spontaneously hypertensive rats.

CONCLUSIONS

FAM3A is an important regulator of vascular constriction and blood pressure. Overactivation of HSF1-FAM3A-ATP signaling cascade in VSMCs plays important roles in Ang II-induced hypertension and cardiovascular diseases. Inhibitors of HSF1 could be potentially used to treat hypertension.

The Role of Podocytes and Podocyte-Associated Biomarkers in Diagnosis and Treatment of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is an important public health problem. Podocyte injury is a central event in the mechanism of DKD development. Podocytes are terminally differentiated, highly specialized glomerular visceral epithelial cells critical for the maintenance of the glomerular filtration barrier. Although potential mechanisms by which diabetic milieu contributes to irreversible loss of podocytes have been described, identification of markers that prognosticate either the development of DKD or the progression to end-stage kidney disease (ESKD) have only recently made it to the forefront. Currently, the most common marker of early DKD is microalbuminuria; however, this marker has significant limitations: not all diabetic patients with microalbuminuria will progress to ESKD and as many as 30% of patients with DKD have normal urine albumin levels. Several novel biomarkers indicating glomerular or tubular damage precede microalbuminuria, suggesting that the latter develops when significant kidney injury has already occurred. Because podocyte injury plays a key role in DKD pathogenesis, identification of markers of early podocyte injury or loss may play an important role in the early diagnosis of DKD. Such biomarkers in the urine include podocyte-released microparticles as well as expression of podocyte-specific markers. Here, we review the mechanisms by which podocyte injury contributes to DKD as well as key markers that have been recently implicated in the development and/or progression of DKD and might serve to identify individuals that require earlier preventative care and treatment in order to slow the progression to ESKD.

VEGFR2 Blockade Improves Renal Damage in an Experimental Model of Type 2 Diabetic Nephropathy

The absence of optimal treatments for Diabetic Nephropathy (DN) highlights the importance of the search for novel therapeutic targets. The vascular endothelial growth factor receptor 2 (VEGFR2) pathway is activated in experimental and human DN, but the effects of its blockade in experimental models of DN is still controversial. Here, we test the effects of a therapeutic anti-VEGFR2 treatment, using a VEGFR2 kinase inhibitor, on the progression of renal damage in the BTBR ob/ob (leptin deficiency mutation) mice. This experimental diabetic model develops histological characteristics mimicking the key features of advanced human DN. A VEGFR2 pathway-activation blockade using the VEGFR2 kinase inhibitor SU5416, starting after kidney disease development, improves renal function, glomerular damage (mesangial matrix expansion and basement membrane thickening), tubulointerstitial inflammation and tubular atrophy, compared to untreated diabetic mice. The downstream mechanisms involved in these beneficial effects of VEGFR2 blockade include gene expression restoration of podocyte markers and downregulation of renal injury biomarkers and pro-inflammatory mediators. Several ligands can activate VEGFR2, including the canonical ligands VEGFs and GREMLIN. Activation of a GREMLIN/VEGFR2 pathway, but not other ligands, is correlated with renal damage progression in BTBR ob/ob diabetic mice. RNA sequencing analysis of GREMLIN-regulated genes confirm the modulation of proinflammatory genes and related-molecular pathways. Overall, these data show that a GREMLIN/VEGFR2 pathway activation is involved in diabetic kidney disease and could potentially be a novel therapeutic target in this clinical condition.

Potential of Renin-Angiotensin-Aldosterone System Modulations in Diabetic Kidney Disease: Old Players to New Hope!

Due to a tragic increase in the incidences of diabetes globally, diabetic kidney disease (DKD) has emerged as one of the leading causes of end-stage renal diseases (ESRD). Hyperglycaemia-mediated overactivation of the renin-angiotensin-aldosterone system (RAAS) is key to the development and progression of DKD. Consequently, RAAS inhibition by angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARBs) is the first-line therapy for the clinical management of DKD. However, numerous clinical and preclinical evidences suggested that RAAS inhibition can only halt the progression of the DKD to a certain extent, and they are inadequate to cure DKD completely. Recent studies have improved understanding of the complexity of the RAAS. It consists of two counter-regulatory arms, the deleterious pressor arm (ACE/angiotensin II/AT1 receptor axis) and the beneficial depressor arm (ACE2/angiotensin-(1-7)/Mas receptor axis). These advances have paved the way for the development of new therapies targeting the RAAS for better treatment of DKD. In this review, we aimed to summarise the involvement of the depressor arm of the RAAS in DKD. Moreover, in modern drug discovery and development, an advance approach is the bispecific therapeutics, targeting two independent signalling pathways. Here, we discuss available reports of these bispecific drugs involving the RAAS as well as propose potential treatments based on neurohormonal balance as credible therapeutic strategies for DKD.

Human umbilical cord mesenchymal stem cells pretreated with Angiotensin-II attenuate pancreas injury of rats with severe acute pancreatitis

Mesenchymal stem cells (MSCs) pretreatment is an effective route for improving cell-based therapy of endothelial cell survival, vascular stabilization, and angiogenesis. We hypothesized that the application of human umbilical cord-MSCs (hUC-MSCs) pretreated with angiotensin-II (Ang-II) might be a potential therapeutic approach for severe acute pancreatitis (SAP). Therefore, the effect of Ang-II pretreated hUC-MSCs on SAP was investigated in vitro and in vivo.

METHODS

In the present study, human umbilical cord-derived MSCs pretreated with or without Ang-II were delivered through the tail vein of rats 12 h after induction of SAP. Pancreatitis severity scores and serum lipase levels, as well as the levels of VEGF and VEGFR2 were evaluated.

RESULTS

We found that the administration of Ang-II-MSCs significantly inhibited pancreatic injury, as reflected by reductions of pancreatitis severity scores, serum amylase and serum lipase levels. Furthermore, the reduced apoptotic rate and increased tube formation in human umbilical vein endothelial Cells (HUVEC) were found resulting from the administration of Ang-II-MSC-CM. Moreover, knockdown of VEGFR2 can block the effect of Ang-II-MSC-CM on preventing HUVEC from apoptosis, as well as the capacity of tube formation was also suppressed. In addition, the expression of increased Bcl-2 and alleviated caspase-3 were observed in HUVEC and HUVEC transfectants exposure to Ang-II-MSC-CM.

CONCLUSION

Collectively, these results elucidated that the pretreatment of hUC-MSCs with Ang-II improved the outcome of MSC-based therapy for SAP via enhancing angiogenesis and ameliorating endothelial cell dysfunction in a VEGFR2 dependent manner.

Influence of high glucose on mesangial cell-derived exosome composition, secretion and cell communication

Mesangial cells stimulated with high glucose (HG) exhibit increased intracellular angiotensin II (AngII) synthesis that is correlated with the upregulation of AngII target genes, such as profibrotic cytokines. The intracrine effects of AngII can be mediated by several molecules transferred to other cells via exosomes (Exos), which play a key role in cellular communication under many physiological and pathological conditions. The aim of this study was to investigate the effects of exosomes derived from HG-stimulated human mesangial cells (HG-HMCs) on normal unstimulated HMCs. Exosomes from HMCs (C-Exos) and HG-HMCs (HG-Exos) were obtained from cell culture supernatants. HMCs were incubated with C-Exos or HG-Exos. HG stimulus induced a change in the amount but not the size of Exos. Both C-Exos and HG-Exos contained angiotensinogen and renin, but no angiotensin converting enzyme was detected. Compared with HMCs treated with C-Exos, HMCs treated with HG-Exos presented higher levels of fibronectin, angiotensinogen, renin, AT₁ and AT₂ receptors, indicating that HG-Exos modified the function of normal HMCs. These results suggest that the intercellular communication through Exos may have pathophysiological implications in the diabetic kidney.

Ion channels and transporters in diabetic kidney disease

Type 1 and 2 diabetes mellitus are major medical epidemics affecting millions of patients worldwide. Diabetes mellitus is the leading cause of diabetic kidney disease (DKD), which is the most common cause of end-stage renal disease (ESRD). DKD is associated with significant changes in renal hemodynamics and electrolyte transport. Alterations in renal ion transport triggered by pathophysiological conditions in diabetes can exacerbate hypertension, accelerate renal injury, and are integral to the development of DKD. Renal ion transporters and electrolyte homeostasis play a fundamental role in functional changes and injury to the kidney during DKD. With the large number of ion transporters involved in DKD, understanding the roles of individual transporters as well as the complex cascades through which they interact is essential in the development of effective treatments for patients suffering from this disease. This chapter aims to gather current knowledge of the major renal ion transporters with altered expression and activity under diabetic conditions, and provide a comprehensive overview of their interactions and collective functions in DKD.

Participation of the AngII/TRPC6/NFAT axis in the pathogenesis of podocyte injury in rats with type 2 diabetes

The canonical transient receptor potential channel 6 ion channel is expressed in podocytes and is an important component of the glomerular slit diaphragm. Focal segmental glomerulosclerosis is closely associated with TRPC6 gene mutations, and TRPC6 mediates podocyte injury induced by high glucose. Angiotensin II (AngII) has been revealed to enhance TRPC6 currents in certain types of cells, including podocytes and ventricular myocytes. It has been reported that glucose regulated TRPC6 expression in an AngII‑dependent manner in podocytes and that this pathway is critical in diabetic nephropathy. In the present study, the role of TRPC6 detected by western blotting and reverse transcription‑quantitative polymerase chain reaction in AngII‑mediated podocyte injury was evaluated in rats with type 2 diabetes induced by high‑calorie diets and streptozotocin. The results demonstrated that urinary albumin excretion was elevated, and morphological changes, including glomerular basement membrane thickening and podocyte process effacement, were observed. There was increased expression of AngII and TRPC6 in diabetic rats. The angiotensin receptor blocker valsartan significantly reduced TRPC6 and nuclear factor of activated T‑cells (NFAT) overexpression in diabetic rats. These results in vivo were confirmed by studies in vitro, which demonstrated that inhibition of TRPC6 ameliorated high glucose‑induced podocyte injury by decreasing NFAT mRNA levels. Taken together, the present results suggested that the AngII/TRPC6/NFAT axis may be a crucial signaling pathway in podocytes that is necessary for maintaining the integrity of the glomerular filtration barrier. In addition, TRPC6 may represent a potential therapeutic target for diabetic nephropathy.

ACE gene dosage determines additional autonomic dysfunction and increases renal angiotensin II levels in diabetic mice

OBJECTIVES

The present study aimed to investigate cardiovascular autonomic modulation and angiotensin II (Ang II) activity in diabetic mice that were genetically engineered to harbor two or three copies of the angiotensin-converting enzyme gene.

METHODS

Diabetic and non-diabetic mice harboring 2 or 3 copies of the angiotensin-converting enzyme gene were used in the present study. Animals were divided into 4 groups: diabetic groups with two and three copies of the angiotensin-converting enzyme gene (2CD and 3CD) and the respective age-matched non-diabetic groups (2C and 3C). Hemodynamic, cardiovascular, and autonomic parameters as well as renal Ang II expression were evaluated.

RESULTS

Heart rate was lower in diabetic animals than in non-diabetic animals. Autonomic modulation analysis indicated that the 3CD group showed increased sympathetic modulation and decreased vagal modulation of heart rate variability, eliciting increased cardiac sympathovagal balance, compared with all the other groups. Concurrent diabetes and either angiotensin-converting enzyme polymorphism resulted in a significant increase in Ang II expression in the renal cortex.

CONCLUSION

Data indicates that a small increase in angiotensin-converting enzyme activity in diabetic animals leads to greater impairment of autonomic function, as demonstrated by increased sympathetic modulation and reduced cardiac vagal modulation along with increased renal expression of Ang II.

Combining streptozotocin and unilateral nephrectomy is an effective method for inducing experimental diabetic nephropathy in the 'resistant' C57Bl/6J mouse strain

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease. Animal models are essential tools for designing new strategies to prevent DN. C57Bl/6 (B6) mice are widely used for transgenic mouse models, but are relatively resistant to DN. This study aims to identify the most effective method to induce DN in a type 1 (T1D) and a type 2 diabetes (T2D) model in B6 mice. For T1D-induced DN, mice were fed a control diet, and randomised to streptozotocin (STZ) alone, STZ+unilateral nephrectomy (UNx), or vehicle/sham. For T2D-induced DN, mice were fed a western (high fat) diet, and randomised to either STZ alone, STZ+UNx, UNx alone, or vehicle/sham. Mice subjected to a control diet with STZ +UNx developed albuminuria, glomerular lesions, thickening of the glomerular basement membrane, and tubular injury. Mice on control diet and STZ developed only mild renal lesions. Furthermore, kidneys from mice on a western diet were hardly affected by diabetes, UNx or the combination. We conclude that STZ combined with UNx is the most effective model to induce T1D-induced DN in B6 mice. In our hands, combining western diet and STZ treatment with or without UNx did not result in a T2D-induced DN model in B6 mice.

Hyperglycaemia induced by chronic i.p. and oral glucose loading leads to hypertension through increased Na+ retention in proximal tubule

NEW FINDINGS

What is the central question of the study? Chronic glucose feeding accompanied by glucose injection (i.p.) causes sustained hyperglycaemia and hypertension in rats. The exact reason for the hypertension is not known. We explore some molecular pathways of the renal proximal tubule that might promote Na⁺ retention. What is the main finding and its importance? Development of hypertension was mediated by upregulation of the renal renin-angiotensin system and oxidative stress, acting via the Na⁺ -K⁺ -ATPase α₁ -subunit in the proximal tubule, which appears to pump intracellular Na⁺ into the extracellular space, increasing Na⁺ reabsorption and blood pressure. Targeting the Na⁺ -K⁺ -ATPase α₁ -subunit might provide a therapeutic strategy for treatment of hypertension. Feeding animals glucose-, fructose-, sucrose- and fat-enriched diets can lead to diet-induced hyperglycaemia, the severity of which largely depends on the types and concentrations of the nutrients used and duration of the dietary intervention. As a dietary intervention strategy, we adopted glucose-enriched diet and drinking water, with i.p. glucose injection at a dose previously determined to be effective to establish a sustained hyperglycaemia over a period of 2 weeks. We used four groups of Sprague-Dawley rats: control; glucose treated; glucose plus tempol treated; and glucose plus captopril treated. Blood glucose concentrations started to increase gradually from day 3, peaked (321 mg dl^-1 ) at day 12 and remained at similar levels until the end of the study on day 14 in the glucose treated-group compared with the control group. In contrast, the tempol- and captopril-treated groups showed significantly high glucose concentrations only in the second week. The plasma insulin concentration was significantly increased in glucose-treated animals but not in tempol- and captopril-treated groups when compared with the control rats. We also observed elevated blood pressure in the glucose-treated group compared with the control group, which can be attributed to the increase in angiotensin II concentrations from 46.67 to 99 pg ml^-1 (control versus glucose), increased oxidative stress in the cortical proximal tubule (PT), decreased urine flow, and increased expression and activity of the PT-specific α₁ -subunit of Na⁺ -K⁺ -ATPase in the renal cortex, which is responsible for increased sodium reabsorption from epithelial cells of PT into the peritubular capillaries, leading to increased blood volume and eventual blood pressure. All these events were reversed in captopril- and tempol-treated animals.

Development and biological evaluation of vesicles containing bile salt of telmisartan for the treatment of diabetic nephropathy

The aim of present study was to develop and evaluate vesicles containing bile salt formulation of telmisartan for the treatment of diabetic nephropathy. Different vesicles containing bile salt formulations were developed by varying ratios of soybean phosphatidylcholine and sodium deoxycholate. Prepared formulations were characterized for their size, polydispersity index, zeta potential, morphology and entrapment efficiency. Further, the renoprotective outcome of optimized formulation was studied in streptozotocin-induced diabetic nephropathy rat model. Results of the present study demonstrated that the average vesicles size, polydispersity index, zeta potential and entrapment efficiency were found to be in the range of 64.98 ± 1.40 to 167.60 ± 6.46 nm, 0.02 ± 0.04 to 0.31 ± 0.01, -24.30 ± 1.39 to -42.60 ± 6.67 mV and 29.68 ± 1.08% to 77.21 ± 0.52%, respectively. Further, the best chosen formulation F4 presented vesicles size, polydispersity index, zeta potential and entrapment efficiency of 64.98 ± 1.40 nm, 0.24 ± 0.02, -35.40 ± 1.48 mV and 77.21 ± 0.52%, respectively. In addition, formulation F4 improved the biological indices in streptozotocin-induced diabetic nephropathy in rats. It was concluded that prepared formulation exerts a valuable results on diabetic nephropathy and it may be a potential pharmaceutical dosage form for the treatment of diabetic nephropathy.

Assessment of Vitamin D-Binding Protein and Early Prediction of Nephropathy in Type 2 Saudi Diabetic Patients

Early detection of diabetic nephropathy (DN) represents a great challenge in an attempt to reduce the burden of chronic kidney diseases in diabetic patients. This study aimed to investigate the potential early prediction role of urinary vitamin D-binding protein (uVDBP) for the diagnosis of DN and to examine the possible correlation to serum VDBP, high-sensitivity C-reactive protein (hs-CRP), and insulin resistance in these patients. Serum and urine samples were obtained from 40 healthy volunteers and 120 patients with type 2 diabetes divided into 3 groups: normoalbuminuria, microalbuminuria, and macroalbuminuria (urinary albumin excretion rate < 30, 30-300, and >300 μg/mg, resp.); n = 40/group. Serum and urinary VDBP levels were quantified by ELISA. Insulin resistance has been assessed by homeostasis model assessment index (HOMAI). Correction for urine creatinine concentration was applied for urinary quantitative measurements. uVDBP levels were significantly elevated in micro- and macroalbuminuria patient groups compared with those of the normoalbuminuria patient group and controls (820.4 ± 402.8 and 1458.1 ± 210.0 compared with 193.1 ± 141.0 and 127.7 ± 21.9 ng/mg, resp.) (P < 0.001). There was significant correlation between serum and urinary levels of VDBP in total patient group. Receiver operating characteristic analysis of uVDBP levels showed optimum cut-off value of 216.0 ng/mg corresponding to 98.8% sensitivity and 80.0% specificity and an area under the curve of 0.973 to discriminate the normoalbuminuria from the microalbuminuria groups. In multivariate analysis, ordination plot showed obvious demarcation between the study groups caused by the higher levels of uVDBP and albumin/creatinine ratio among other variables. The study findings suggested a possible clinical application of uVDPB as an early and a good marker for the detection of early renal disease in type 2 DM Saudi patients. Large-scale validation studies are warranted to confirm the results before including uVDBP with the available list of other conventional biomarkers.

Eprosartan mesylate loaded bilosomes as potential nano-carriers against diabetic nephropathy in streptozotocin-induced diabetic rats

The objective of the present study was to formulate eprosartan mesylate loaded nano-bilosomes and investigates its potential for controlling streptozotocin induced diabetes nephropathy in Wistar rats. The eprosartan mesylate loaded nano-bilosomes comprising of various ratios of soybean phosphatidylcholine/sodium deoxycholate were prepared by thin film hydration technique. The prepared formulations were evaluated for vesicles size, polydispersity index, zeta potential and entrapment efficiency. Further the optimized formulation was characterized for vesicles morphology, and its efficacy for the management of diabetic nephropathy in Wistar rats. The optimized eprosartan mesylate loaded nano-bilosomes exhibited vesicles size, polydispersity index, zeta potential and entrapment efficiency of 63.88±3.46nm, 0.172±0.026, -30.40±2.75mV and 61.19±0.88% respectively. In vivo activity demonstrated that the prepared eprosartan mesylate loaded nano-bilosomes formulation demonstrated a nephro-protecting outcome as shown by the substantial decrease in serum creatinine, urea, lactate dehydrogenase, total albumin, and malondialdehyde. Additionally, an oral administration of eprosartan mesylate loaded nano-bilosomes decreases the raised expressions of Angiotensin II type 1 receptor, inducible nitric oxide synthase, and transforming growth factor-β1 in Wistar rats. Further, histopathological examination established the nephro-protective effect of prepared formulation. In conclusion, the research work in the paper suggests that the prepared eprosartan mesylate loaded nano-bilosomes could serve as a practical oral formulation for diabetic nephropathy in future therapy and may offer potential benefits in cases with hypertension and renal disease.

Association of angiotensin-II levels with albuminuria in subjects with normal glucose metabolism, prediabetes, and type 2 diabetes mellitus

OBJECTIVES

The relationship between the renin-angiotensin system (RAS) and diabetes has been studied for many years. However, studies that assessed RAS components comprehensively were limited. We hypothesized that serum RAS components, especially the effector peptide angiotensin-II, might be closely associated with glucose metabolism status and diabetic complications.

METHODS

We investigated the association of individual RAS component with albuminuria in 407 subjects with normal glucose metabolism (NGM), prediabetes, or type 2 diabetes mellitus (T2DM). Anthropometric and biochemical parameters, including glucose homeostasis, albuminuria, and RAS-related parameters such as plasma renin activity (PRA), aldosterone, angiotensin-converting enzyme (ACE), and angiotensin-II levels, were measured.

RESULTS

The mean±standard deviation (SD) age and body mass index were 57.1±11.1years and 24.7±3.3kg/m², respectively. There were 54 subjects with NGM, 102 with prediabetes, and 251 with T2DM. The mean±SD angiotensin-II levels in these groups were 9.32±6.89, 12.89±10.39, and 17.00±15.28pg/mL, and the respective urinary albumin-to-creatinine ratios (ACRs) were 8.1±5.3, 13.3±17.3, and 30.7±51.9mg/g, which were significantly different among the groups. The serum angiotensin-II levels were correlated with levels of PRA, insulin resistance, C-reactive protein, and urinary ACR. Among RAS-related parameters, only the angiotensin-II level was significantly associated with urinary ACR after adjusting for relevant risk factors.

CONCLUSIONS

Angiotensin-II may play an important role in the development of albuminuria, particularly in subjects with impaired glucose metabolism.

The locally activated renin-angiotensin system is involved in albumin permeability in glomerular endothelial cells under high glucose conditions

Background

Although the diabetic milieu per se , hemodynamic changes, oxidative stress and local growth factors such as angiotensin II (AII) are considered to be mediators in the pathogenesis of diabetic nephropathy, the underlying pathways mediating the changes in glomerular endothelial cells (GECs) are not well understood. Therefore, we investigated changes in the renin-angiotensin system (RAS) components in high glucose (HG)-stimulated GECs and the role of the local RAS in morphological and functional changes in GECs under diabetic conditions.

Methods

We stimulated GECs with 5.6 mM glucose or 30 mM glucose with or without an angiotensin II type I receptor blocker (ARB) in vitro and also performed experiments with Sprague-Dawley rats injected with diluent ( n = 16) or streptozotocin [ n = 16, diabetes (DM)]. Eight rats from each group were treated with ARB for 3 months in vivo . Real-time polymerase chain reaction, western blot analysis, enzyme-linked immunosorbent assay and immunofluorescent staining using cultured GECs were performed. The permeability of GECs to macromolecules was assessed by measuring the passage of fluorescein isothiocyanate-labeled bovine serum albumin. Morphological changes were also evaluated by scanning and transmission electron microscopy.

Results

There were significant increases in angiotensinogen expression in HG-stimulated GECs along with significant increases in AI and AII levels. Moreover, the expression of heparan sulfate glycosaminoglycans (HS-GAG) assessed by immunofluorescent staining was significantly lower and the permeability to albumin was significantly higher in GECs exposed to HG medium, and ARB treatment significantly abrogated these changes. Upon electron microscopy examination, the mean size of the GEC fenestrae was significantly greater in HG-stimulated GECs and DM rats, and these increases were significantly ameliorated by ARB.

Conclusions

The local RAS within GECs was activated under HG conditions, and this activation may be associated with both an alteration in GEC fenestration and a decrease in HS-GAG, resulting in the development of albuminuria in diabetic nephropathy.

Changes in Urinary Angiotensinogen Associated with Deterioration of Kidney Function in Patients with Type 2 Diabetes Mellitus

Urinary angiotensinogen (AGT) is potentially a specific biomarker for the status of the intrarenal renin-angiotensin system (RAS) in patients with diabetes mellitus. We explored whether changes in urinary AGT excretion levels were associated with the deterioration of kidney function in type 2 diabetes patients with preserved kidney function. Urinary baseline AGT levels were measured in 118 type 2 diabetic patients who were not taking RAS blockers and who had estimated glomerular filtration rates (eGFRs) ≥ 60 mL/min/1.73 m². A total of 91 patients were followed-up for 52 months. Changes in urinary levels of AGT (ΔAGT) were calculated by subtracting urinary AGT/creatinine (Cr) at baseline from urinary AGT/Cr after 1 year. ΔAGT was significantly inversely correlated with annual eGFR change (β = -0.29, P = 0.006; β = -0.37, P = 0.001 after adjusting for clinical factors). RAS blockers were prescribed in 36.3% of patients (n = 33) during follow-up. The ΔAGT values were lower in the RAS blockers users than in the non-RAS blockers users, but the differences were not statistically significant (7.37 ± 75.88 vs. 22.55 ± 57.45 μg/g Cr, P = 0.081). The ΔAGT values remained significantly correlated with the annual rate of eGFR change (β = -0.41, P = 0.001) in the patients who did not use RAS blockers, but no such correlation was evident in the patients who did. ΔAGT is inversely correlated with annual changes in eGFR in type 2 diabetes patients with preserved kidney function, particularly in RAS blocker-naïve patients.

Renoprotection: focus on TRPV1, TRPV4, TRPC6 and TRPM2

Members of the transient receptor potential (TRP) cation channel receptor family have unique sites of regulatory function in the kidney which enables them to promote regional vasodilatation and controlled Ca²⁺ influx into podocytes and tubular cells. Activated TRP vanilloid 1 receptor channels (TRPV1) have been found to elicit renoprotection in rodent models of acute kidney injury following ischaemia/reperfusion. Transient receptor potential cation channel, subfamily C, member 6 (TRPC6) in podocytes is involved in chronic proteinuric kidney disease, particularly in focal segmental glomerulosclerosis (FSGS). TRP vanilloid 4 receptor channels (TRPV4) are highly expressed in the kidney, where they induce Ca²⁺ influx into endothelial and tubular cells. TRP melastatin (TRPM2) non-selective cation channels are expressed in the cytoplasm and intracellular organelles, where their inhibition ameliorates ischaemic renal pathology. Although some of their basic properties have been recently identified, the renovascular role of TRPV1, TRPV4, TRPC6 and TRPM2 channels in disease states such as obesity, hypertension and diabetes is largely unknown. In this review, we discuss recent evidence for TRPV1, TRPV4, TRPC6 and TRPM2 serving as potential targets for acute and chronic renoprotection in chronic vascular and metabolic disease.

Telmisartan decreases microalbuminuria in patients with type 2 diabetes mellitus following coronary artery bypass grafting

Objective:

This prospective study aimed to investigate the effects of the selective angiotensin receptor antagonist, telmisartan, on microalbuminuria after coronary artery bypass surgery in patients with diabetes mellitus.

Methods:

Patients were divided into two groups with block randomisation, using the sealed envelope technique: group T (telmisartan group) consisted of patients who received the angiotensin receptor blocking agent telmisartan 80 mg daily for at least six months in the pre-operative period; group N-T (non-telmisartan group) consisted of patients who received no telmisartan treatment. Clinical and demographic characteristics, operative and postoperative features, microalbuminuria and high-sensitivity C-reactive protein levels were compared.

Results:

Forty patients met the eligibility criteria for the study. The groups did not differ with regard to clinical and demographic characteristics, and operative and postoperative features. Microalbuminuria levels between the groups differed significantly in the pre-operative period, first hour postoperatively and fifth day postoperatively. C-reactive protein levels between the groups differed significantly on the fifth day postoperatively.

Conclusion:

Telmisartan was useful for decreasing systemic inflammation and levels of urinary albumin excretion in patients who had type 2 diabetes mellitus and had undergone coronary artery bypass surgery.

Protective effect of L-glutamine against diabetes-induced nephropathy in experimental animal: Role of KIM-1, NGAL, TGF-β1, and collagen-1

Diabetic nephropathy is a serious microvascular complication and one of the main causes of end-stage renal disease. L-Glutamine (LG) is naturally occurring amino acids with antidiabetic and antioxidant potential. The aim of present investigation was to evaluate the potential of LG against streptozotocin (STZ)-induced diabetic nephropathy (DN) in laboratory rats. DN was induced in male Wistar rats (200-220 g) by intraperitoneal administration of STZ (55 mg/kg). Animals were treated orally with either distilled water (10 mg/kg) or LG (250, 500, and 1000 mg/kg) or Sitagliptin (5 mg/kg). Various biochemical, molecular, and histological (hematoxylin-eosin and Masson's trichrome stain) parameters were assessed. Administration of LG (500 and 1000 mg/kg) significantly inhibited (p < .05) STZ-induced alterations in serum and urine biochemistry (urine creatinine, uric acid, albumin, and BUN). It also significantly increased creatinine clearance rate. STZ induced increase in renal oxidonitrosative stress was significantly decreased (p < .05) by LG (500 and 1000 mg/kg) treatment. Upregulated renal KIM-1, NGAL, TGF-β1, and collagen-1 mRNA expression after STZ administration was significantly inhibited (p < .05) by LG (500 and 1000 mg/kg) treatment. Correlation analysis also revealed that antidiabetic potential of LG attenuates STZ-induced elevated renal KIM-1, NGAL, TGF-β1, and collagen-1 mRNA expression. Histopathological alteration induced by STZ in renal tissue was ameliorated by LG treatment. In conclusion, results of present investigation suggest that treatment with LG ameliorated STZ-induced DN via the inhibition of oxidonitrosative stress as well as downregulation of KIM-1, NGAL, TGF-β1, and collagen-1 mRNA expressions.

Selection of a high-affinity and in vivo bioactive ssDNA aptamer against angiotensin II peptide

Unique features of aptamers have attracted interests for a broad range of applications. Aptamers are able to specifically bind to targets and inhibit their functions. This study, aimed to isolate the high affinity ssDNA aptamers against bio-regulator peptide angiotensin II (Ang II) and investigate their bioactivity in cellular and animal models. To isolate ssDNA aptamers, 12 rounds of affinity chromatography SELEX (Systematic Evolution of Ligands by EXponential enrichment) procedure were carried out. The SPR (surface plasmon resonance) and ELONA (enzyme linked oligonucleotide assay) analysis were used to determine the affinity and specificity of aptamers. The ability of selected aptamers to inhibit the proliferative effect of Ang II on human aortic vascular smooth muscle cells (HA-VSMCs) and their performance on Wistar rat urinary system and serum electrolyte levels were investigated. Two full-length aptamers (FLC112 and FLC125) with high affinity of respectively 7.52±2.44E-10 and 5.87±1.3E-9M were isolated against Ang II. The core regions of these aptamers (CRC112 and CRC125) also showed affinity of 5.33±1.15E-9 and 4.11±1.09E-9M. In vitro analysis revealed that FLC112 and FLC125 can inhibit the proliferative effect of Ang II on HA-VSMCs (P<0.05). They also significantly reduced the serum sodium level and increased the urine volume (P<0.05). The core regions of aptamers did not show high inhibitory potential against Ang II. It can be a spotlight that ssDNA aptamers have high potential for blocking Ang II. In conclusion, it appears that the researches focusing on high affinity and bioactive aptamers may lead to excellent results in blocking Ang II activity.

Diabetic nephropathy: where are we on the journey from pathophysiology to treatment?

Diabetic nephropathy affects 30-40% of people with diabetes, and is the leading cause of end-stage kidney disease. The current treatment paradigm relies on early detection, glycaemic control and tight blood pressure management with preferential use of renin-angiotensin system blockade. This strategy has transformed outcomes in diabetic kidney disease over the last 20 years. Over the last two decades we have also witnessed significant advances in the understanding of the pathophysiology of diabetic nephropathy; however, despite this new knowledge, we have yet to develop new treatments of proven efficacy. Whilst a continued emphasis on preclinical and clinical research is clearly needed, clinicians treating people with diabetes should not forget that, in the short term, the greatest gains are likely to be realised by more consistent deployment of existing therapies.

Risk of proteinuria among individuals with persistent borderline diabetes: the Saku study

OBJECTIVE

To investigate the risk of decreased estimated glomerular filtration rate (eGFR) and proteinuria among individuals with borderline diabetes.

METHODS

This 5-year cohort study involved 2849 participants aged 30-79 years without diabetes or chronic kidney disease at baseline (April 2008-March 2009). Participants were categorized into two groups-normoglycemia and borderline diabetes-based on the results of a 75-g oral glucose tolerance test at baseline. Participants underwent annual comprehensive medical check-ups during the follow-up period until March 2014. Main outcomes were defined as proteinuria ≥[1+] or eGFR <60 ml/min/1.73 m2. Cox proportional hazards regression was used to estimate the hazard ratio (HR) and 95 % confidence interval (CI) of eGFR <60 ml/min/1.73 m2 and proteinuria ≥[1+] for the borderline diabetes group compared with the normoglycemia group.

RESULTS

During the follow-up period, 335 individuals developed eGFR <60 ml/min/1.73 m2 and 136 individuals developed proteinuria ≥[1+]. Participants in the borderline diabetes group did not have a significantly higher risk of eGFR <60 ml/min/1.73 m2 or proteinuria ≥[1+] after multivariable adjustment. However, participants with borderline diabetes who were also diagnosed with borderline diabetes at the endpoint examination had a significantly higher risk of proteinuria ≥[1+] compared with participants with normoglycemia who also had normoglycemia at the endpoint examination; the HR (95 % CI) was 1.76 (1.11-2.78).

CONCLUSIONS

Persistent borderline diabetes significantly increases the risk of proteinuria.

Podocytes: the Weakest Link in Diabetic Kidney Disease?

Diabetes is increasing in prevalence and is the leading cause of end-stage renal disease in the United States. Diabetic kidney disease is considered a proteinuric glomerular disease. Although the glomerulus is composed of various cell types, research suggests that podocytes are critical to overall glomerular health. Podocyte injury has been identified as a pivotal event resulting in proteinuric kidney disease, glomerulosclerosis, and loss of renal function. Thus, understanding the signaling mechanisms that trigger podocyte injury in diabetic kidney disease might allow for the development of targeted therapeutics to prevent or ameliorate progression to end-stage renal failure. This review focuses on the role of podocytes in diabetic kidney disease.

Podocyte hypertrophy precedes apoptosis under experimental diabetic conditions

Podocyte hypertrophy and apoptosis are two hallmarks of diabetic glomeruli, but the sequence in which these processes occur remains a matter of debate. Here we investigated the effects of inhibiting hypertrophy on apoptosis, and vice versa, in both podocytes and glomeruli, under diabetic conditions. Hypertrophy and apoptosis were inhibited using an epidermal growth factor receptor inhibitor (PKI 166) and a pan-caspase inhibitor (zAsp-DCB), respectively. We observed significant increases in the protein expression of p27, p21, phospho-eukaryotic elongation factor 4E-binding protein 1, and phospho-p70 S6 ribosomal protein kinase, in both cultured podocytes exposed to high-glucose (HG) medium, and streptozotocin-induced diabetes mellitus (DM) rat glomeruli. These increases were significantly inhibited by PKI 166, but not by zAsp-DCB. In addition, the amount of protein per cell, the relative cell size, and the glomerular volume were all significantly increased under diabetic conditions, and these changes were also blocked by treatment with PKI 166, but not zAsp-DCB. Increased protein expression of cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase, together with increased Bax/Bcl-2 ratios, were also observed in HG-stimulated podocytes and DM glomeruli. Treatment with either zAsp-DCB or PKI 166 resulted in a significant attenuation of these effects. Both PKI 166 and zAsp-DCB also inhibited the increase in number of apoptotic cells, as assessed by Hoechst 33342 staining and TUNEL assay. Under diabetic conditions, inhibition of podocyte hypertrophy results in attenuated apoptosis, whereas blocking apoptosis has no effect on podocyte hypertrophy, suggesting that podocyte hypertrophy precedes apoptosis.

Involvement of Histone Lysine Methylation in p21 Gene Expression in Rat Kidney In Vivo and Rat Mesangial Cells In Vitro under Diabetic Conditions

Diabetic nephropathy (DN), a common complication associated with type 1 and type 2 diabetes mellitus (DM), characterized by glomerular mesangial expansion, inflammation, accumulation of extracellular matrix (ECM) protein, and hypertrophy, is the major cause of end-stage renal disease (ESRD). Increasing evidence suggested that p21-dependent glomerular and mesangial cell (MC) hypertrophy play key roles in the pathogenesis of DN. Recently, posttranscriptional modifications (PTMs) have uncovered novel molecular mechanisms involved in DN. However, precise regulatory mechanism of histone lysine methylation (HKme) mediating p21 related hypertrophy associated with DN is not clear. We evaluated the roles of HKme and histone methyltransferase (HMT) SET7/9 in p21 gene expression in glomeruli of diabetic rats and in high glucose- (HG-) treated rat mesangial cells (RMCs). p21 gene expression was upregulated in diabetic rats glomeruli; chromatin immunoprecipitation (ChIP) assays showed decreased histone H3-lysine9-dimethylation (H3K9me2) accompanied with enhanced histone H3-lysine4-methylation (H3K4me1/3) and SET7/9 occupancies at the p21 promoter. HG-treated RMCs exhibited increased p21 mRNA, H3K4me level, SET7/9 recruitment, and inverse H3K9me, which were reversed by TGF-β1 antibody. These data uncovered key roles of H3Kme and SET7/9 responsible for p21 gene expression in vivo and in vitro under diabetic conditions and confirmed preventive effect of TGF-β1 antibody on DN.

Sodium and Potassium Relating to Parkinson's Disease and Traumatic Brain Injury

Alkali metals, especially sodium and potassium, are plentiful and vital in biological systems. They take on important roles in health and disease. Such roles include the regulation of homeostasis, osmosis, blood pressure, electrolytic equilibria, and electric current. However, there is a limit to our present understanding; the ions have a great ability and capacity for action in health and disease, much greater than our current understanding. For the regulation of physiological homeostasis, there is a crucial regulator (renin-angiotensin system, RAS), found at both peripheral and central levels. Misregulation of the Na(+)-K(+) pump, and sodium channels in RAS are important for the understanding of disease progression, hypertension, diabetes, and neurodegenerative diseases, etc. In particular, RAS displays direct or indirect interaction important to Parkinson's disease (PD). In this chapter, the relationship between the regulation of sodium/potassium concentration and PD was sought. In addition, some recent biochemical and clinical findings are also discussed that help describe sodium and potassium in the context of traumatic brain injury (TBI). TBI is caused from the heavy striking of the head; this strongly affects ion flux in the affected tissue (brain) and damages cellular regulation systems. Thus, inappropriate concentrations of ions (hyper- and hyponatremia, and hyper- and hypokalemia) will perturb homeostasis giving rise to important and far reaching effects. These changes also impact osmotic pressure and the concentration of other metal ions, such as the calcium(II) ion.