Potential of Modulating Aldosterone Signaling and Mineralocorticoid Receptor with microRNAs to Attenuate Diabetic Kidney Disease.

Diabetic Kidney Disease (DKD) is a significant complication of diabetes and primary cause of end-stage renal disease globally. The exact mechanisms underlying DKD remain poorly understood, but multiple factors, including the renin-angiotensin-aldosterone system (RAAS), play a key role in its progression. Aldosterone, a mineralocorticoid steroid hormone, is one of the key components of RAAS and a potential mediator of renal damage and inflammation in DKD. miRNAs, small noncoding RNA molecules, have attracted interest due to their regulatory roles in numerous biological processes. These processes include aldosterone signaling and mineralocorticoid receptor (MR) expression. Numerous miRNAs have been recognized as crucial regulators of aldosterone signaling and MR expression. These miRNAs affect different aspects of the RAAS pathway and subsequent molecular processes, which impact sodium balance, ion transport, and fibrosis regulation. This review investigates the regulatory roles of particular miRNAs in modulating aldosterone signaling and MR activation, focusing on their impact on kidney injury, inflammation, and fibrosis. Understanding the complex interaction between miRNAs and the RAAS could lead to a new strategy to target aldosterone signaling and MR activation using miRNAs. This highlights the potential of miRNA-based interventions for DKD, with the aim of enhancing kidney outcomes in individuals with diabetes.

The proteinuria-lowering effects of dapagliflozin are associated with an initial decline in estimated glomerular filtration rate in patients with chronic kidney disease.

AIM: Sodium-glucose co-transporter-2 inhibitor, dapagliflozin (DAPA) reduced albuminuria and slowed down the decline in estimated glomerular filtration rate (eGFR) in patients with chronic kidney disease (CKD) in the DAPA-CKD trial. However, proteinuria (albuminuria) does not necessarily decrease in all patients in real-world clinical settings. Therefore, we aimed to identify the clinical characteristics of patients with CKD and decreased proteinuria in response to DAPA treatment. METHODS: Of 106 patients with CKD, 54 patients were finally included who received 10 mg of DAPA once daily. Patients whose urinary protein-to-creatinine ratio (UPCR) decreased by >30% or ≤30% from baseline after 1 month of treatment were defined as responders and non-responders, respectively. RESULTS: At baseline, median eGFR and UPCR were 45.3 mL/min/1.73 m2 (interquartile range [IQR], 29.7, 54.6) and 1.09 g/gCr (IQR, 0.52, 1.91), respectively. After 1 month of treatment, the mean decline in eGFR and reduction in UPCR was 6.5% (standard deviation [SD], 7.2%) and 6.6% (SD, 42.1%) from baseline, respectively. Moreover, the blood pressure, eGFR, and uric acid decreased significantly from baseline, but haemoglobin and serum potassium did not change. The median UPCR decreased significantly in patients with UPCR ≥0.5 g/gCr, but not <0.5 g/gCr at baseline. UPCR responders had a greater initial decline in eGFR at 1 month than non-responders. CONCLUSION: The percent changes in UPCR were positively associated with the initial decline rate in eGFR in patients with CKD with a UPCR ≥0.5 g/gCr at baseline after 1 month of DAPA treatment.

Gut Microbiome and Microbiome-Derived Metabolites in Patients with End-Stage Kidney Disease.

The composition of the gut microbiome is altered in patients with chronic kidney disease (CKD). Dysbiosis leads to decreased levels of stool organic acids (OAs) and systemic inflammation, followed by accumulation of uremic toxins (UTs) and the development of end-stage kidney disease (ESKD). We assessed the relationship between the microbiome and UT levels or the development of ESKD by comparing patients undergoing hemodialysis (HD) and those with normal renal function (NRF). This cross-sectional study recruited 41 patients undergoing HD and 38 sex- and age-matched patients with NRF, and gut microbiome, levels of plasma UTs, inflammatory markers, and stool OAs were compared. The indices of beta-diversity differed significantly between patients with NRF and those undergoing HD, and between patients undergoing HD with and without type 2 diabetes. The levels of stool total OA, inflammatory markers, and UTs differed significantly between the patients with NRF and those undergoing HD. The combined main effects of type 2 diabetes and kidney function status were accumulation of indoxyl sulfate and p-cresyl sulfate. The relative abundances of Negativicutes and Megamonas were associated with development of ESKD and with the levels of UTs, even after adjustment for factors associated with the progression of ESKD. The present study indicates that the gut environment differs between patients with NRF and those undergoing HD and between patients undergoing HD with and without type 2 diabetes. Moreover, ESKD patients with diabetes accumulate more UTs derived from the gut microbiome, which might be associated with cardio-renal diseases and poor prognosis.

Sodium-Glucose Cotransporter-2 Inhibitors-Miracle Drugs for the Treatment of Chronic Kidney Disease Irrespective of the Diabetes Status: Lessons from the Dedicated Kidney Disease-Focused CREDENCE and DAPA-CKD Trials.

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease (CKD) and end-stage kidney disease worldwide. In Japan, the proportion of new patients requiring dialysis due to DKD has remained unchanged over the past five years. Early diagnosis and treatment are extremely important for the prevention of DKD progression. Albuminuria is the most promising biomarker currently available for diagnosing DKD and predicting its prognosis at an early stage; however, it has relatively poor specificity and sensitivity for DKD. Measuring the serum levels of tumor necrosis factor receptors (TNFRs; TNFR1 and TNFR2) is an alternative for predicting the prognosis of patients with CKD, irrespective of their diabetes status. Cardiorenal risk factor management and renin-angiotensin system inhibitor usage are effective in slowing the DKD progression, although the residual risk remains high in patients with DKD. Recently, two classes of antihyperglycemic agents, sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide-1 receptor agonists, in addition to nonsteroidal selective mineralocorticoid receptor antagonists, which are less potent blood pressure-lowering and potassium-sparing agents, have emerged as cardiorenal disease-modifying therapies for preventing the DKD progression. This review focused on the SGLT2 inhibitor-based therapeutic strategies that have demonstrated cardiorenal benefits in patients with type 2 diabetes.

Circulating Tumor Necrosis Factor Receptors: A Potential Biomarker for the Progression of Diabetic Kidney Disease.

Despite considerable advancements in medicine, the optimal treatment for chronic kidney disease (CKD), especially diabetic kidney disease (DKD), remains a major challenge. More patients with DKD succumb to death due to cardiovascular events than due to progression to end-stage renal disease (ESRD). Moreover, patients with DKD and ESRD have remarkably poor prognosis. Current studies have appreciated the contribution of inflammation and inflammatory mediators, such as tumor necrosis factor (TNF)-related biomarkers, on the development/progression of DKD. The present review focuses on molecular roles, serum concentrations of TNF receptors (TNFRs), and their association with increased albuminuria, eGFR decline, and all-cause mortality in diabetes. Experimental studies have suggested that DKD progression occurs through the TNFα-TNFR2 inflammatory pathway. Moreover, serum TNFR levels were positively associated with albuminuria and negatively associated with estimated glomerular filtration rate (eGFR), while circulating levels of TNFRs exhibited an independent effect on all-cause mortality and eGFR decline, including ESRD, even after adjusting for existing risk factors. However, their precise function has yet to be elucidated and requires further studies.

Effect of Zinc Acetate Dihydrate (NobelzinR) Treatment on Anemia and Taste Disorders in Patients with Chronic Kidney Disease with Hypozincemia.

Some patients with chronic kidney disease (CKD) receiving hemodialysis develop erythropoietin-resistant anemia, possibly due to zinc deficiency. The frequency of zinc deficiency in CKD (stages 1-5 and 5D) and CKD improvement via zinc supplementation are not completely verified. Here 500 CKD patients (Stage 1/2, n=100; Stage 3, n=100; Stage 4, n=100, Stage n=5, 100; Stage 5D, n=100) will be recruited to determine the frequency of serum zinc deficiency at each CKD stage. Patients with serum zinc concentrations <80 µg/dL will be treated with zinc acetate dihydrate (NobelzinR) to evaluate its effects on hypozincemia, taste disturbances, and anemia.

Effect of tonsillectomy with steroid pulse therapy on circulating tumor necrosis factor receptors 1 and 2 in IgA nephropathy.

BACKGROUND: High circulating levels of soluble tumor necrosis factor receptors (TNFRs: TNFR1, TNFR2) predict renal function decline in a variety of kidney diseases. Tonsillectomy with steroid pulse (TSP) therapy has been reported as a remission induction therapy in IgA nephropathy (IgAN), mainly in Japan. However, little is known about whether TNFR levels change after TSP therapy in patients with IgAN. METHODS: Two hundred twenty-three patients with IgAN were stratified according to the estimated glomerular filtration rate (eGFR): Group I (eGFR ≥ 60 mL/min/1.73 m2, n = 172) and Group II (eGFR < 60 mL/min/1.73 m2, n = 51). We measured serum TNFR levels with immunoassay in all patients at the time of renal biopsy, and also in patients whose samples just before the first (after tonsillectomy) (n = 34) and/or the third steroid pulse therapy (n = 77) were available. RESULTS: The TNFR levels were significantly higher in Group II than in Group I. A significant negative correlation was observed between TNFR levels and eGFR at baseline (TNFRs: r > -0.50). In multivariate logistic regression analysis, both TNFRs were associated with renal function decline, independent of age and uric acid levels. Proteinuria and hematuria remarkably improved after TSP therapy, as expected. In comparison with baseline TNFR levels, the levels of TNFR2, but not TNFR1, decreased significantly just before the third steroid pulse therapy, although both levels did not change after tonsillectomy. CONCLUSIONS: The TNFR2 level did not change after tonsillectomy alone but decreased significantly after steroid pulse therapy in patients with IgAN.

Role of the TNF pathway in the progression of diabetic nephropathy in KK-A(y) mice.

Chronic inflammation promotes the progression of diabetic nephropathy (DN). However, the role of TNF-α remains unclear. The objectives of the present study were to examine whether TNF-α inhibition with a soluble TNF receptor (TNFR)2 fusion protein, i.e., etanercept (ETN), improves the early stage of DN in the type 2 diabetic model of the KK-A(y) mouse and to also investigate which TNF pathway, TNFR1 or TNFR2, is predominantly involved in the progression of this disease. ETN was injected intraperitoneally into mice for 8 wk. Renal damage was evaluated by immunohistochemistry, Western blot analysis, and/or real-time PCR. In vitro, mouse tubular proximal cells were stimulated by TNF-α and/or high glucose (HG) and treated with ETN. ETN dramatically improved not only albuminuria but also glycemic control. Renal mRNA and/or protein levels of TNFR2, but not TNF-α and TNFR1, in ETN-treated KK-A(y) mice were significantly decreased compared with untreated KK-A(y) mice. mRNA levels of ICAM-1, VCAM-1, and monocyte chemoattractant protein-1 and the number of F4/80-positive cells were all decreased after treatment. Numbers of cleaved caspase-3- and TUNEL-positive cells in untreated mice were very few and were not different from ETN-treated mice. In vitro, stimulation with TNF-α or HG markedly increased both mRNA levels of TNFRs, unlike in the in vivo case. Furthermore, ETN partly recovered TNF-α-induced but not HG-induced TNFR mRNA levels. In conclusion, it appears that ETN may improve the progression of the early stage of DN predominantly through inhibition of the anti-inflammatory action of the TNF-α-TNFR2 pathway.

Effect of proteinuria on the rapid kidney function decline in chronic kidney disease depends on the underlying disease: A post hoc analysis of the BRIGHTEN study.

AIMS: It is unclear whether the effect of proteinuria on rapid kidney function decline is equivalent among diabetic kidney disease (DKD), non-DKD with diabetes (NDKD+DM), and nephrosclerosis without diabetes (NS-DM), particularly in advanced chronic kidney disease patients. METHODS: In total, 1038 chronic kidney disease patients who participated in the BRIGHTEN study were included in the present study. A linear mixed effect model was applied to estimate the annual estimated glomerular filtration rate decline in each disease group. RESULTS: The prevalence of rapid decliners (rapid kidney function decline, defined as an eGFR loss of > 5 mL/min/1.73 m2/year) in the DKD group (44.6 %) was significantly higher compared with the NDKD+DM (27.9 %) and NS-DM (27.0 %) groups. By contrast, the prevalence of rapid decliners in different urine total protein to creatinine ratio (UPCR) categories (<0.5, 0.5 to < 1.0, 1.0 to < 3.5, and ≥ 3.5 g/g) were equivalent between the DKD and NS-DM groups. Moreover, the prevalence of a UPCR < 1.0 g/g in rapid decliners of the NS-DM group was more than double than in those of the DKD and NDKD+DM groups. CONCLUSIONS: The risk of rapid kidney function decline in NS-DM patients with low levels of proteinuria may be greater than initially predicted.

Progranulin deficiency attenuates tubulointerstitial injury in a mouse unilateral ureteral obstruction model.

Progranulin (PGRN) may have two opposing effects-inflammation and anti-inflammation-in different diseases. Although previous studies have reported that PGRN is involved in liver fibrosis, its involvement in tubulointerstitial fibrosis remains to be fully elucidated. Herein, we investigated these issues using PGRN-knockout (KO) mice treated with unilateral ureteral obstruction (UUO). Eight-week-old male PGRN-KO and wild-type (WT) mice were euthanized 3 and 7 days following UUO, and their kidneys were harvested for histopathological analysis. The renal expression of PGRN was evaluated by immunohistochemical and/or western blot analyses. The renal mRNA levels of markers related to inflammation (Il1b, Tnf, Il6, Ccl2, and Adgre1) and fibrosis (Tgfb1, Acta2, Fn1, and Col1a2) were evaluated using quantitative PCR. Histological changes such as renal tubular atrophy, urinary casts, and tubulointerstitial fibrosis were significantly improved in UUO-KO mice compared with UUO-WT mice. Quantitative PCR revealed that the mRNA expression levels of all inflammation- and fibrosis-related markers were lower in UUO-KO mice than in UUO-WT mice at 3 and/or 7 days after UUO. Moreover, PGRN and GRN protein levels were higher in the kidneys of UUO-WT mice than in mice that did not undergo UUO. Elevated GRN levels associated with excess PGRN levels may be involved in the occurrence of renal inflammation and fibrosis in UUO mice.

Circulating TNF receptor levels are associated with estimated glomerular filtration rate even in healthy individuals with normal kidney function.

The association between serum tumor necrosis factor receptor (TNFRs: TNFR1, TNFR2) levels and estimated glomerular filtration rate (eGFR) observed in patients with diabetes has not been comprehensively tested in healthy subjects with normal kidney function. It also remains unclear whether TNFR levels differ by age and sex, and between healthy subjects and diabetics. We measured serum TNFR levels in 413 healthy subjects and 292 patients with type 2 diabetes. In healthy subjects, TNFR levels did not differ between men and women. Additionally, TNFR2, but not TNFR1, levels increased with age. In multivariate analysis, TNFR1 was associated only with cystatin C-based eGFR (eGFR-CysC), whereas TNFR2 was associated with systolic blood pressure in addition to eGFR-CysC. Both TNFRs were associated with lower eGFR (eGFR-Cys < 90 mL/min/1.73 m2) even after adjustment for relevant clinical factors. Upon combining healthy subjects and patients with diabetes, the presence of diabetes and elevated glycated hemoglobin level were significant factors in determining TNFR levels. TNFR levels were associated with eGFR-CysC, but were not affected by age and sex in healthy subjects with normal kidney function. TNFR levels in patients with diabetes appeared to be higher than in healthy subjects.

A systematic review of progranulin concentrations in biofluids in over 7,000 people-assessing the pathogenicity of GRN mutations and other influencing factors.

BACKGROUND: Pathogenic heterozygous mutations in the progranulin gene (GRN) are a key cause of frontotemporal dementia (FTD), leading to significantly reduced biofluid concentrations of the progranulin protein (PGRN). This has led to a number of ongoing therapeutic trials aiming to treat this form of FTD by increasing PGRN levels in mutation carriers. However, we currently lack a complete understanding of factors that affect PGRN levels and potential variation in measurement methods. Here, we aimed to address this gap in knowledge by systematically reviewing published literature on biofluid PGRN concentrations. METHODS: Published data including biofluid PGRN concentration, age, sex, diagnosis and GRN mutation were collected for 7071 individuals from 75 publications. The majority of analyses (72%) had focused on plasma PGRN concentrations, with many of these (56%) measured with a single assay type (Adipogen) and so the influence of mutation type, age at onset, sex, and diagnosis were investigated in this subset of the data. RESULTS: We established a plasma PGRN concentration cut-off between pathogenic mutation carriers and non-carriers of 74.8 ng/mL using the Adipogen assay based on 3301 individuals, with a CSF concentration cut-off of 3.43 ng/mL. Plasma PGRN concentration varied by GRN mutation type as well as by clinical diagnosis in those without a GRN mutation. Plasma PGRN concentration was significantly higher in women than men in GRN mutation carriers (p = 0.007) with a trend in non-carriers (p = 0.062), and there was a significant but weak positive correlation with age in both GRN mutation carriers and non-carriers. No significant association was seen with weight or with TMEM106B rs1990622 genotype. However, higher plasma PGRN levels were seen in those with the GRN rs5848 CC genotype in both GRN mutation carriers and non-carriers. CONCLUSIONS: These results further support the usefulness of PGRN concentration for the identification of the large majority of pathogenic mutations in the GRN gene. Furthermore, these results highlight the importance of considering additional factors, such as mutation type, sex and age when interpreting PGRN concentrations. This will be particularly important as we enter the era of trials for progranulin-associated FTD.

Circulating tumor necrosis factor-related biomarkers predict kidney function decline in Japanese patients with diabetes: An observational cohort study.

AIMS: Tumor necrosis factor (TNF) receptors (TNFRs: TNFR1 and, TNFR2) are reportedly associated with chronic kidney disease (CKD) progression chiefly in Caucasian patients with diabetes. We assessed the prognostic value of TNF-related biomarkers for CKD progression in Japanese patients with diabetes. METHODS: We estimated TNF-related biomarkers using an enzyme-linked immunosorbent assay in 640 patients with diabetes. Cox proportional hazards analysis was performed to estimate hazard ratios (HRs) per one standard deviation (SD) increase in a log-transformed biomarker. The kidney and the composite outcome were defined as a 30% reduction in estimated glomerular filtration rate (eGFR) from baseline, and kidney outcome plus death before kidney outcome, respectively. RESULTS: During the median follow-up of 5.4 years, 75 (11.7%) patients reached the kidney outcome and 37 (5.8%) died before reaching the kidney outcome. Each SD increase in baseline circulating TNFR1, TNFR2, and ephrin type-A receptor 2 (EphA2) was associated with a higher risk of the kidney outcome independently from baseline eGFR and urine albumin-to-creatinine ratio. However, circulating osteoprotegerin was associated with the composite outcome only. CONCLUSIONS: Elevated TNFR1, TNFR2, and EphA2 were associated with both kidney and composite outcomes in Japanese patients with diabetes.

Circulating tumor necrosis factor receptors are associated with mortality and disease severity in COVID-19 patients.

BACKGROUND: Although hyperinflammatory response influences the severity of coronavirus disease 2019 (COVID-19), little has been reported about the utility of tumor necrosis factor (TNF)-related biomarkers in reflecting the prognosis. We examined whether TNF receptors (TNFRs: TNFR1, TNFR2) and progranulin (PGRN) levels, in addition to interleukin 6 (IL-6) and C-reactive protein (CRP), are associated with mortality or disease severity in COVID-19 patients. METHODS: This retrospective study was conducted at Juntendo University Hospital. Eighty hospitalized patients with various severities of COVID-19 were enrolled. Furthermore, serum levels of TNF-related biomarkers were measured using enzyme-linked immunosorbent assay. RESULTS: Twenty-five patients died during hospitalization, and 55 were discharged. The median (25th and 75th percentiles) age of the study patients was 70 (61-76) years, 44 (55.0%) patients were males, and 26 (32.5%) patients had chronic kidney disease (CKD). When comparing with patients who received and did not receive treatment at the intensive care unit (ICU), the former had a higher tendency of being male and have diabetes, hypertension, and CKD; had higher levels of white blood cells, D-dimer, and lactate dehydrogenase; and had lower body mass index, estimated glomerular filtration rate, and lymphocyte counts. Significant differences were observed in TNFR, PGRN, IL-6, and CRP levels between each severity (mild-severe) group. Furthermore, the serum levels of TNFR, IL-6, and CRP, but not PGRN, in ICU patients were significantly higher than in the patients who were not admitted to the ICU. Multivariate logistic regression analysis demonstrated that high levels of TNFR2 were only associated with mortality in patients with COVID-19 even after adjustment for relevant clinical parameters. CONCLUSIONS: High TNFR2 level might be helpful for predicting mortality or disease severity in patients with COVID-19.

Development of an In-House EphA2 ELISA for Human Serum and Measurement of Circulating Levels of EphA2 in Hypertensive Patients with Renal Dysfunction.

Identifying novel biomarkers of kidney function in patients with chronic kidney disease (CKD) has strong clinical value as current measures have limitations. This study aims to develop and validate a sensitive and specific ephrin type-A receptor 2 (EphA2) enzyme-linked immunosorbent assay (ELISA) for human serum, and determine whether its results correlate with traditional renal measures in patients with hypertension. The novel ELISA of the current study was validated and used to measure circulating EphA2 levels in 80 hypertensive patients with and without kidney function decline (eGFR less than 60 mL/min/1.73 m2). Validation of the EphA2 ELISA showed good recovery (87%) and linearity (103%) and no cross-reactivity with other Eph receptors. Patients with kidney function decline had lower diastolic blood pressure, and higher UPCR and EphA2 than those without kidney function decline. The association of age and eGFR with EphA2 was maintained in the stepwise multiple regression analysis. In a multivariate logistic model, EphA2 was associated with a lower eGFR (<60 mL/min/1.73 m2) after adjustment for age, sex, and UPCR. High circulating EphA2 levels have potential application as a clinical biomarker for the presence of CKD in patients with hypertension.

Progranulin and Its Receptor Predict Kidney Function Decline in Patients With Type 2 Diabetes.

Progranulin (PGRN), a growth factor, is abundantly expressed in a broad range of tissues and cell types with pleiotropic functions including inflammation, neurodegeneration, and facilitating lysosome acidification. PGRN binds to TNF receptors (TNFR) and inhibits downstream inflammatory signaling pathways. TNFR is a well-known predictor of glomerular filtration rate (GFR) decline in a variety of diseases. Therefore, we measured circulating PGRN in addition to TNFR using an enzyme-linked immunosorbent assay and explored whether it predicted renal prognosis in 201 Japanese patients with type 2 diabetes. During a median follow-up of 7.6 years, 21 participants reached primary renal endpoint, which involves a decline of at least 57% in eGFR from baseline, or the onset of end-stage renal disease. Univariate Cox regression analysis revealed that classical renal measures (GFR and albuminuria), two TNF-related biomarkers (PGRN and TNFR), and BMI were associated with this outcome. Multivariate analysis demonstrated that high levels of PGRN [HR 2.50 (95%CI 2.47-2.52)] or TNFR1 [HR 5.38 (95%CI 5.26-5.50)] were associated with this outcome after adjusting for relevant covariates. The high levels of PGRN as well as TNFR1 were associated with a risk of primary renal outcome in patients with type 2 diabetes after adjusting for established risk factors.

Attenuating effect of angiotensin-(1-7) on angiotensin II-mediated NAD(P)H oxidase activation in type 2 diabetic nephropathy of KK-A(y)/Ta mice.

ANG-(1-7) is associated with vasodilation and nitric oxide synthase stimulation. However, the role of ANG-(1-7) in type 2 diabetes mellitus is unknown. In this study, we examined the hypothesis that ANG-(1-7) attenuates ANG II-induced reactive oxygen species stress (ROS)-mediated injury in type 2 diabetic nephropathy of KK-A(y)/Ta mice. KK-A(y)/Ta mice were divided into four groups: 1) a control group; 2) ANG II infusion group; 3) ANG II+ANG-(1-7) coinfusion group; and 4) ANG II+ANG-(1-7)+d-Ala(7)-ANG-(1-7) (A779) coinfusion group. In addition, primary mesangial cells were cultured and then stimulated with 25 mM glucose with or without ANG II, ANG-(1-7), and A779. The ANG II+ANG-(1-7) coinfusion group showed a lower urinary albumin/creatinine ratio increase than the ANG II group. ANG-(1-7) attenuated ANG II-mediated NAD(P)H oxidase activation and ROS production in diabetic glomeruli and mesangial cells. ANG II-induced NF-κB and MAPK signaling activation was also attenuated by ANG-(1-7) in the mesangial cells. These findings were related to improved mesangial expansion and to fibronectin and transforming growth factor-ß1 production in response to ANG II and suggest that ANG-(1-7) may attenuate ANG II-stimulated ROS-mediated injury in type 2 diabetic nephropathy. The ACE2-ANG-(1-7)-Mas receptor axis should be investigated as a novel target for treatment of type 2 diabetic nephropathy.

Mindin: a novel marker for podocyte injury in diabetic nephropathy.

BACKGROUND: GeneChip Expression Analysis was employed to survey the glomerular gene expression profile in a type 2 diabetes (T2D) model of KK/Ta mice fed with a high-calorie diet (HC), and we focused on the role of mindin (also called spondin 2), whose expression is upregulated by HC. METHODS: Isolated glomeruli from three 20-week-old KK/Ta mice fed with HC or a standard diet (SD) were dissected. Total RNA was extracted and labelled for hybridization using the Affymetrix GeneChip Mouse Genome 430 2.0 Array. The gene expression profile was compared between the HC and SD groups using GeneSpring 7.3.1 software. Mindin expression was examined using real-time PCR, western blot analysis and immunohistochemical staining in the glomeruli, cultured podocytes and urine samples of both mice and humans. RESULTS: Podocyte foot process effacement was observed in mice fed with HC. The mindin protein expression levels in mice were localized in the podocytes, and their levels in the glomeruli were increased in the HC group compared with the SD group. The levels of urinary mindin in the HC group at 16 weeks of age were also significantly higher than those in the SD group although albumin/creatinine ratio (ACR) did not differ between the groups. Furthermore, the levels in patients with T2D were higher than those in healthy individuals and increased gradually with increases in ACR. CONCLUSIONS: Mindin could be related to podocyte injury and appears to be an early biomarker of the progression of diabetic nephropathy.

Effect of combination therapy with angiotensin receptor blocker and 1,25-dihydroxyvitamin D(3) in type 2 diabetic nephropathy in KK-A(y)/Ta mice.

BACKGROUND: Although angiotensin II type 1 receptor blockers (ARB) have beneficial effects in patients with diabetic nephropathy, they may induce a compensatory increase in renin. Renin exhibits profibrotic actions independent of angiotensin II, which is regulated by extracellular signal-regulated kinase 1 and 2 (ERK1/2). Calcitriol (1,25(OH)(2)D(3)) is a negative inhibitor of the renin-angiotensin system and the present study examined the effects of combination therapy with an ARB and 1,25(OH)(2)D(3) on diabetic nephropathy in KK-A(y)/Ta mice. METHODS: KK-A(y)/Ta mice were divided into four groups: ARB group, 1,25(OH)(2)D(3) group, combination group, and control group. The urinary albumin/creatinine ratio (ACR) was measured and the renal expression of renin, p-ERK1/2 and TGF-ß1 protein determined. RESULTS: The levels of urinary ACR in the combination group were significantly lower than those in the ARB or control group. Renal expression of renin in the ARB group was significantly increased compared with the control group but was significantly decreased in both the 1,25(OH)(2)D(3) and combination group. Renal expression of p-ERK1/2 in the combination group was significantly decreased compared with the control or ARB group. Expression of TGF-ß1 protein in the ARB and combination groups, especially the combination group, was significantly decreased compared with those in the control group. CONCLUSIONS: These data suggest that the addition of 1,25(OH)(2)D(3) to therapy with ARB further reduced proteinuria by suppressing the compensatory increase in renin expression in type 2 diabetic nephropathy. These effects might relate to suppression of renin, ERK1/2 and TGF-ß1 expression which may or may not depend on angiotensin II.

Differential organ-specific inflammatory response to progranulin in high-fat diet-fed mice.

Progranulin (PGRN) has been reported to bind tumor necrosis factor (TNF) receptor and to inhibit TNFα signaling. We evaluated the effect of augmentation of TNFα signaling by PGRN deficiency on the progression of kidney injury. Eight-week-old PGRN knockout (KO) and wild-type (WT) mice were fed a standard diet or high-fat diet (HFD) for 12 weeks. Albuminuria, markers of tubular damage, and renal mRNA levels of inflammatory cytokines were higher in HFD-fed KO (KO-HFD) mice than in HFD-fed WT (WT-HFD) mice. Body weight, vacuolization in proximal tubules, and systemic and adipose tissue inflammatory markers were lower in the KO-HFD mice than in the WT-HFD mice. The renal megalin expression was lower in the KO mice than in the WT mice regardless of the diet type. The megalin expression was also reduced in mouse proximal tubule epithelial cells stimulated with TNFα and in those with PGRN knockdown by small interfering RNA in vitro. PGRN deficiency was associated with both exacerbated renal inflammation and decreased systemic inflammation, including that in the adipose tissue of mice with HFD-induced obesity. Improved tubular vacuolization in the KO-HFD mice might partially be explained by the decreased expression of megalin in proximal tubules.