Normoalbuminuric diabetic kidney disease

Development of the Diabetic Kidney Disease Mouse Model Culturing Embryos in α-Minimum Essential Medium In Vitro, and Feeding Barley Diet Attenuated the Pathology

Diabetic kidney disease (DKD) is a critical complication associated with diabetes; however, there are only a few animal models that can be used to explore its pathogenesis. In the present study, we established a mouse model of DKD using a technique based on the Developmental Origins of Health and Disease theory, i.e., by manipulating the embryonic environment, and investigated whether a dietary intervention could ameliorate the model's pathology. Two-cell embryos were cultured in vitro in α-minimum essential medium (MEM; MEM mice) or in standard potassium simplex-optimized medium (KSOM) as controls (KSOM mice) for 48 h, and the embryos were reintroduced into the mothers. The MEM and KSOM mice born were fed a high-fat, high-sugar diet for 58 days after they were 8 weeks old. Subsequently, half of the MEM mice and all KSOM mice were fed a diet containing rice powder (control diet), and the remaining MEM mice were fed a diet containing barley powder (barley diet) for 10 weeks. Glomerulosclerosis and pancreatic exhaustion were observed in MEM mice, but not in control KSOM mice. Renal arteriolar changes, including intimal thickening and increase in the rate of hyalinosis, were more pronounced in MEM mice fed a control diet than in KSOM mice. Immunostaining showed the higher expression of transforming growth factor beta (TGFB) in the proximal/distal renal tubules of MEM mice fed a control diet than in those of KSOM mice. Pathologies, such as glomerulosclerosis, renal arteriolar changes, and higher TGFB expression, were ameliorated by barley diet intake in MEM mice. These findings suggested that the MEM mouse is an effective DKD animal model that shows glomerulosclerosis and renal arteriolar changes, and barley intake can improve these pathologies in MEM mice.

Clinical and Pathological Characteristics of Patients With Nonproteinuric Diabetic Nephropathy

INTRODUCTION

As the most common complication of diabetes mellitus (DM), diabetic nephropathy (DN) was initially considered to begin with proteinuria preceding the progression of renal insufficiency. This clinical paradigm has been questioned in the late decades, as many DM patients without proteinuria have progressive renal insufficiency. However, the characteristics of nonproteinuric DN were not fully clear yet.

PATIENTS AND METHODS

A total of 390 patients with renal biopsy-proven DN in our center were retrospectively recruited in the current study. Clinical and histopathological data of the patients were analyzed. We used propensity score-matching methods to address the imbalance of age, sex, and diabetes duration for comparative analyses.

RESULTS

Among all the renal biopsy-proven DN patients with renal biopsy proven DN, 18 patients were classified as nonproteinuric DN. Compared with 36 propensity score-matched proteinuric DN patients, diabetic retinopathy (DR) was less frequent in nonproteinuric DN patients (38.9% vs. 66.4%, p<0.05). During the follow-up of 24.0 (12.0-42.0) months, the probability of developing the end-stage renal disease (ESRD) was significantly lower in nonproteinuric DN patients than in proteinuric ones in both the propensity score-matched cohort and overall cohort (log-rank test, p<0.001 and p<0.001, respectively).

CONCLUSIONS

Compared with proteinuric DN patients, DR was less frequent in nonproteinuric DN patients. Nonproteinuric DN patients had better renal outcomes than proteinuric DN patients.

Circulating microRNA-194 levels in Chinese patients with diabetic kidney disease: a case-control study

OBJECTIVE

MicroRNAs (miRNAs) regulate gene expression and are involved in diabetic kidney disease (DKD) pathogenesis. We investigated circulating miRNA-194 levels as a biomarker of DKD prevalence and incidence, and the relationship between miRNA-194 and CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP).

METHODS

We recruited 136 type-2 diabetes mellitus (T2DM) patients at the First People's Hospital of Lianyungang and 127 healthy individuals. Circulating miRNA-194 and CHOP levels were measured using quantitative reverse transcription qRT-PCR and enzyme-linked immunosorbent assay (ELISA), respectively. Anthropometric and biochemistry measurements were also made.

RESULTS

T2DM patients showed higher circulating miRNA-194 (p = 0.029) and lower circulating CHOP (p < 0.001) levels than controls. Circulating miRNA-194 levels were significantly higher in T2DM patients with a microalbumin/creatinine ratio (UmALB/Cr) ⩾ 300 mg/g (p < 0.001). In addition, there were significant intergroup differences in the circulating CHOP concentrations (p = 0.005). Bivariate analysis revealed that circulating miR-194 levels were negatively correlated with alpha-fetoprotein and CHOP levels (r = -0.222, -0.301; p = 0.018, 0.001, respectively), but positively correlated with fasting glucose, UmALB/Cr, Cr, Cystatin C, quantitative insulin check index (QUICKI) (r = 0.193, 0.446, 0.260, 0.339, and 0.250, respectively; p = 0.036, <0.001, 0.005, <0.001, and 0.006, respectively), particularly UmALB/Cr and Cystatin C (p < 0.001). Logistic regression analysis after adjusting for covariates associated with UmALB/Cr identified duration of T2DM, systolic blood pressure, Cr, estimated glomerular filtration rate, and waist circumference as independent factors associated with T2DM patients with UmALB/Cr > 300 (p = 0.030, 0.013, <0.001, <0.001, and 0.031, respectively).

CONCLUSION

Circulating miRNA-194 levels could be a novel biomarker for DKD.

Development of a Biomarker Panel to Distinguish Risk of Progressive Chronic Kidney Disease

Chronic kidney disease (CKD) patients typically progress to kidney failure, but the rate of progression differs per patient or may not occur at all. Current CKD screening methods are sub-optimal at predicting progressive kidney function decline. This investigation develops a model for predicting progressive CKD based on a panel of biomarkers representing the pathophysiological processes of CKD, kidney function, and common CKD comorbidities. Two patient cohorts are utilised: The CKD Queensland Registry (n = 418), termed the Biomarker Discovery cohort; and the CKD Biobank (n = 62), termed the Predictive Model cohort. Progression status is assigned with a composite outcome of a ≥30% decline in eGFR from baseline, initiation of dialysis, or kidney transplantation. Baseline biomarker measurements are compared between progressive and non-progressive patients via logistic regression. In the Biomarker Discovery cohort, 13 biomarkers differed significantly between progressive and non-progressive patients, while 10 differed in the Predictive Model cohort. From this, a predictive model, based on a biomarker panel of serum creatinine, osteopontin, tryptase, urea, and eGFR, was calculated via linear discriminant analysis. This model has an accuracy of 84.3% when predicting future progressive CKD at baseline, greater than eGFR (66.1%), sCr (67.7%), albuminuria (53.2%), or albumin-creatinine ratio (53.2%).

Prevalence of chronic kidney disease in an admixed population of patients with type 1 diabetes. A multicenter study in Brazil

AIMS

To evaluate diagnosis, prevalence and associated factors of CKD in Brazilian patients with type 1 diabetes.

METHODS

This cross-sectional, multicenter study was conducted in 14 public clinics in 10 Brazilian cities. From 1760 patients, 1736 were included (98.6%): 977 females (56.3%), 932 (54%) Caucasians, aged 29.9 ± 11.9 years, age at diagnosis 14.7 ± 8.9 years, diabetes duration 15.5 ± 9.3 years and 12.2 ± 3.8 years of school attendance. CKD was determined by using estimated glomerular filtration rate and by the presence of albuminuria in two out of three morning urine samples.

RESULTS

The prevalence of CKD was 33.7%. Overall, 28.1% of the patients could not be classified due to insufficient number of urine samples for albuminuria determination. Multivariable analysis showed that female gender, diabetes duration, high levels of HbA1c and uric acid, use of renin-angiotensin system inhibitors, retinopathy, high systolic blood pressure, and economic status (medium, low and very low) were associated with CKD.

CONCLUSIONS

Although a high prevalence of CKD, associated comorbidities and retinopathy was observed in our study, a large number of patients are still undiagnosed, making CKD a challenge in routine clinical practice in admixed populations with T1D in a developing country like Brazil.

Urine Metabolomics Analysis in Patients With Normoalbuminuric Diabetic Kidney Disease

Objective

Diabetic kidney disease (DKD) leads to low high albuminuria and gradually progresses to very high albuminuria with kidney insufficiency. However, about 20–40% of DKD is normoalbuminuric DKD (NADKD), which has impaired kidney function but normal urine albumin. This study is to investigate the urine metabolomic profiles of patients with NADKD and albuminuria DKD (ADKD).

Methods

In total, 95 patients were divided into a simple diabetes mellitus group (SDM group), an ADKD group, and a NADKD group. All subjects were analyzed for urine metabolites using non-targeted metabolomics based on ultra-performance liquid chromatography – tandem mass spectrometry.

Results

The urine metabolomic profiles of the SDM group, NADKD group, and ADKD group were significantly different, and 65 different metabolites were identified among the three groups. Metabolic pathway analysis of these differential metabolites found that the top three significantly changed metabolic pathways were linoleic acid metabolism, citrate cycle, and, arginine and proline metabolism. There are 12 metabolites enriched in these three metabolic pathways. In detail, compared with those in the SDM group, the levels of γ-linolenic acid in the ADKD group were increased significantly, while the levels of succinic acid, cis-aconitic acid, citric acid, L-proline, L-erythro-4-hydroxyglutamate, N-methylhydantoin, N-carbamoylputrescine, spermidine, and 5-aminopentanoic acid were reduced significantly; compared with those in the NADKD group, the levels of linoleic acid, γ-linolenic acid, and L-malic acid in the ADKD group were increased significantly (P < 0.05), while the levels of L-proline, L-erythro-4-hydroxyglutamate, N-carbamoylputrescine, and spermidine were significantly reduced (P < 0.05). However, there were no significant difference between the SDM group and NADKD group (P > 0.05).

Conclusion

The urine metabolomic profiles between the NADKD group and the ADKD group are significantly different. Specifically, these two groups have distinct levels of linoleic acid, γ-linolenic acid, L-malic acid, L-proline, L-erythro-4-hydroxyglutamate, N-carbamoylputrescine, and spermidine.

Method for evaluating the human bioequivalence of acarbose based on pharmacodynamic parameters

Objective

To explore a method for evaluating the bioequivalence of acarbose based on pharmacodynamic parameters using a single-dose, randomized-sequence, three-way crossover study of acarbose test (T) and reference (R) formulations.

Methods

Baseline-adjusted, pre-dose value deduction, and direct comparison methods were used to evaluate the geometric T/R ratios and 90% confidence intervals (CIs) of the ln-transformed pharmacodynamic parameters to identify the most suitable evaluation system. Twelve participants were randomly divided into three groups to receive treatment in the following sequences: TRR, RTR, and RRT, each including a 7-day washout period between treatment periods. The serum glucose concentration (baseline) was determined. Pharmacodynamic parameters, including the maximum reduction in serum glucose concentrations (ΔC_SG,max) and difference of the AUC of glucose between before and after acarbose exposure (ΔAUEC), were tested.

Results

Using the direct comparison method, the geometric mean ratios of C_SG,max, AUEC_(0-2h), and AUEC_(0-4h) were 94.13%, 97.82% and 99.76%, respectively. The 90% CIs of the geometric T/R ratios for C_SG,max, AUEC_(0-2h), and AUEC_(0-4h) all fell between 80% and 125%. Conversely, ΔC_SG,max and ΔAUEC_(0-4h) were less reliable measures of acarbose bioequivalence.

Conclusions

Pre-dose value deduction and direct comparison methods can be initially considered suitable for assessing acarbose bioequivalence.

Potential Repressive Impact of microRNA-20a on Renal Tubular Damage in Diabetic Kidney Disease by Targeting C-X-C Motif Chemokine Ligand 6

BACKGROUND AND AIMS

C-X-C Motif Chemokine Ligand 6 (CXCL6) is an important chemokine. We attempt in this investigation to explore its role and possible mechanism in diabetic kidney disease (DKD).

METHODS

By intergrating GEO data, CXCL6 expression in DKD patients and normal controls was exhibited. miRWalk website and luciferase reporter assay were used to predict and verify the upstream miRNA of CXCL6. CCK-8 assay and flow cytometry were performed to detect proliferation and apoptosis capacities. The levels of inflammatory key factors (TNF-α, IL-6 and IL-8) were measured using ELISA analysis. Expression of CXCL6, miR-20a, and JAK/STAT3 pathway-related markers were detected by qRT-PCR or western blot assays.

RESULTS

CXCL6 was increased in DKD. miR-20a was identified as an upstream regulatory miRNA of CXCL6, and its expression was decreased in DKD and HG-treated HK-2 cells. miR-20a overexpression facilitated the proliferation of HG-treated HK-2 cells, whereas miR-20a depletion exhibited the opposite phenomenon. The levels of TNF-α, IL-6 and IL-8 were increased by HG treatment in HK-2 cells. CXCL6 antagonized the promoting impacts of miR-20a mimics on HG-exposed HK-2 cell proliferation. The suppressive effect of miR-20a overexpression on apoptosis and inflammatory response of HG-induced HK-2 cell was rescued by CXCL6 enhancement. The protein expression of p-JAK and p-STAT3 were reduced by miR-20a mimic while facilitated by CXCL6 overexpression in HG-stimulated HK-2 cells.

CONCLUSION

These consequences hinted that miR-20a might exert a repressive impact on DKD, possibly through targeting CXCL6 and mediating JAK/STAT3 pathway, which offer new targets for DKD treatment.

DsbA-L deficiency exacerbates mitochondrial dysfunction of tubular cells in diabetic kidney disease

Excessive mitochondrial fission has been identified as the central pathogenesis of diabetic kidney disease (DKD), but the precise mechanisms remain unclear. Disulfide-bond A oxidoreductase-like protein (DsbA-L) is highly expressed in mitochondria in tubular cells of the kidney, but its pathophysiological role in DKD is unknown. Our bioinformatics analysis showed that tubular DsbA-L mRNA levels were positively associated with eGFR but negatively associated with Scr and 24h-proteinuria in CKD patients. Furthermore, the genes that were coexpressed with DsbA-L were mainly enriched in mitochondria and were involved in oxidative phosphorylation. In vivo, knockout of DsbA-L exacerbated diabetic mice tubular cell mitochondrial fragmentation, oxidative stress and renal damage. In vitro, we found that DsbA-L was localized in the mitochondria of HK-2 cells. High glucose (HG, 30 mM) treatment decreased DsbA-L expression followed by increased mitochondrial ROS (mtROS) generation and mitochondrial fragmentation. In addition, DsbA-L knockdown exacerbated these abnormalities, but this effect was reversed by overexpression of DsbA-L. Mechanistically, under HG conditions, knockdown DsbA-L expression accentuated JNK phosphorylation in HK-2 cells. Furthermore, administration of a JNK inhibitor (SP600125) or the mtROS scavenger MitoQ significantly attenuated JNK activation and subsequent mitochondrial fragmentation in DsbA-L-knockdown HK-2 cells. Additionally, the down-regulation of DsbA-L also amplified the gene and protein expression of mitochondrial fission factor (MFF) via the JNK pathway, enhancing its ability to recruit DRP1 to mitochondria. Taken together, these results link DsbA-L to alterations in mitochondrial dynamics during tubular injury in the pathogenesis of DKD and unveil a novel mechanism by which DsbA-L modifies mtROS/JNK/MFF-related mitochondrial fission.

Metabolomics window into the role of acute kidney injury after coronary artery bypass grafting in diabetic nephropathy progression

Introduction

Metabolomics has emerged as a valuable tool to discover novel biomarkers and study the pathophysiology of diabetic nephropathy (DN). However, the effect of postoperative acute kidney injury (AKI) on diabetes mellitus (DM) to chronic DN progression has not been evaluated from the perspective of metabolomics.

Methods

A group of type 2 diabetes mellitus (T2DM) inpatients, who underwent off-pump coronary artery bypass grafting (CABG), were enrolled in our study. According to whether postoperative AKI occurred, patients were grouped in either the AKI group (AKI, n = 44) or the non-AKI group (NAKI, n = 44). Urine samples were collected from these patients before and 24 h after operation. Six patients from the AKI group and six patients from the NAKI group were chosen as the pilot cohort for untargeted metabolomics analysis, with the goal of identifying postoperative AKI-related metabolites. To understand the possible role of these metabolites in the chronic development of renal injury among T2DM patients, trans-4-hydroxy-L-proline and azelaic acid were quantified by targeted metabolomics analysis among 38 NAKI patients, 38 AKI patients, 46 early DN patients (DN-micro group), and 34 overt DN patients (DN-macro group).

Results

Untargeted metabolomics screened 61 statistically distinguishable metabolites in postoperative urine samples, compared with preoperative urine samples. Via Venn diagram analysis, nine of 61 were postoperative AKI-related metabolites, including trans-4-hydroxy-L-proline, uridine triphosphate, p-aminobenzoate, caffeic acid, adrenochrome, δ-valerolactam, L-norleucine, 5′-deoxy-5′-(methylthio) adenosine, and azelaic acid. By targeted metabolomics analysis, the level of trans-4-hydroxy-L-proline increased gradually from the NAKI group to the AKI, DN-micro, and DN-macro groups. For azelaic acid, the highest level was found in the NAKI and DN-micro groups, followed by the DN-macro group. The AKI group exhibited the lowest level of azelaic acid.

Conclusions

The detection of urinary trans-4-hydroxy-L-proline after AKI could be treated as an early warning of chronic DN progression and might be linked to renal fibrosis. Urinary azelaic acid can be used to monitor renal function noninvasively in DM and DN patients. Our results identified markers of AKI on DM and the chronic progression of DN. In addition, the progression of DN was associated with AKI-like episodes occurring in DM.

LncRNA MALAT1 promoted high glucose-induced pyroptosis of renal tubular epithelial cell by sponging miR-30c targeting for NLRP3

Diabetic nephropathy (DN), characterized by the chronic loss of kidney function during diabetes, is a long-term kidney disease that affects millions of populations. However, the etiology of DN remains unclear. DN cell model was established by treating HK-2 cells with high glucose (HG) in vitro. Expression of metastasis-associated lung adenocarcinoma transcript-1 (MALAT1), miR-30c, nucleotide binding and oligomerization domain-like receptor protein 3 (NLRP3), caspase-1, IL-1β, and IL-18 in treated HK-2 cells were tested by quantitative polymerase chain reaction. HK-2 cell pyroptosis was assessed using flow cytometry analysis. Lactate dehydrogenase (LDH) activity was examined with a LDH assay kit. Correlation among MALAT1, miR-30c, and NLRP3 was examined via dual-luciferase reporter assay. Here, we revealed that MALAT1 was upregulated, but miR-30c was downregulated in HG-treated HK-2 cells, leading to upregulation of NLRP3 expression and cell pyroptosis. Knockdown of MALAT1 or overexpression of miR-30c protected HK-2 cells from HG-induced pyroptosis. Meanwhile, we found that MALAT1 promoted NLRP3 expression by sponging miR-30c through dual-luciferase reporter assay. Moreover, the co-transfection of sh-MALAT1 and miR-30c inhibitor could reverse the protective effects of the sh-MALAT1 on the HG-induced pyroptosis. These results confirmed that MALAT1 regulated HK-2 cell pyroptosis by inhibiting miR-30c targeting for NLRP3, contributing to a better understanding of DN pathogenesis and help to find out the effective treatment for DN.

Design and validation of a scoring model for differential diagnosis of diabetic nephropathy and nondiabetic renal diseases in type 2 diabetic patients

BACKGROUND

We aim to design a scoring model for differential diagnosis between diabetic nephropathy (DN) and nondiabetic renal disease (NDRD) in type 2 diabetic patients through a combination of clinical variables.

METHODS

A total of 170 patients with type 2 diabetes who underwent kidney biopsies were included and divided into three groups according to pathological findings: DN group (n = 46), MIX group (DN + NDRD, n = 54), NDRD group (n = 70). Clinical characteristics and laboratory data were collected and compared among groups. Variables with a significant statistical difference between DN and NDRD patients were analyzed by logistic regression to predict the presence of NDRD; then a scoring model was established based on the regression coefficient and further validated in an independent cohort of 67 patients prospectively.

RESULTS

On biopsy, 72.9% of patients had NDRD, and the most common pathological type was membranous nephropathy. The established scoring model for predicting NDRD included five predictors: age, systolic blood pressure, hemoglobin, duration of diabetes, and absence of diabetic retinopathy. The model demonstrated good discrimination and calibration (area under curve [AUC] 0.863, 95% CI, 0.800-0.925; Hosmer-Lemeshow [H-L] P = .062). Furthermore, high prediction accuracy (AUC = 0.900; 95% CI, 0.815-0.985) in the validation cohort proved the stability of the model.

CONCLUSIONS

We present a simple, robust scoring model for predicting the presence of NDRD with high accuracy (0.85) for the first time. This decision support tool provides a noninvasive method for differential diagnosis of DN and NDRD, which may help clinicians assess the risk-benefit ratio of kidney biopsy for type 2 diabetic patients with renal impairment.

Value of elastography point quantification in improving the diagnostic accuracy of early diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) is a common complication of diabetes. The patient’s prognosis is poor once DKD progresses to advanced stage. Accurate diagnosis and timely treatment of early DKD are important for improving patient’s prognosis and reducing mortality.

AIM

To explore the value of elastography point quantification (ElastPQ) in improving the accuracy of early DKD diagnosis.

METHODS

A total of 69 patients with type 2 diabetes were recruited from Naval Military Medical University Affiliated Gongli Hospital. Patients were divided into early DKD group and medium DKD group according to pathological results and urinary albumin excretion rate (UAER). Another 40 patients with simple diabetes were included as the diabetes group. The baseline data, laboratory diagnostic indicators, and ultrasound indicators for each patient were recorded. The differences of the indicators in the three groups were compared. Multivariate logistic regression was used to analyze the influencing factors of the development from simple diabetes into early DKD and from early DKD into medium DKD. Receiver operating characteristic analyses of potential indicators in identifying early DKD and medium DKD, and early DKD and simple diabetes were established.

RESULTS

Multivariate logistic regression analysis showed that UAER (P < 0.001), renocortical Young's Modulus (YM) (P < 0.001), and renal parenchymal thickness (P = 0.013) were the independent influencing factors of the development from early DKD into medium DKD. Diabetes duration (P = 0.041), UAER (P = 0.034), and renocortical YM (P = 0.017) were the independent influencing factors of the development from simple diabetes into early DKD. Receiver operating characteristic analysis indicated that UAER, renocortical YM, and renal parenchymal thickness were accurate in identifying early DKD and medium DKD [all area under curve (AUC) > 0.9]. The accuracy of UAER (AUC = 0.744), diabetes duration (AUC = 0.757), and renocortical YM (AUC = 0.782) for the diagnosis of early DKD and simple diabetes were limited. However, the combined diagnosis of UAER, diabetes duration, and renocortical YM was accurate in identifying early DKD and simple diabetes (AUC = 0.906), which was significantly higher than any of the three indicators (all P < 0.05).

CONCLUSION

ElastPQ is of great value in the diagnosis of early DKD. When combined with the diabetes duration and UAER, it is expected to diagnose accurately early DKD.

Urinary NGAL and RBP Are Biomarkers of Normoalbuminuric Renal Insufficiency in Type 2 Diabetes Mellitus

Objectives

As a screening index of diabetic kidney disease (DKD), urinary albumin/creatine ratio (UACR) is commonly used. However, approximately 23.3%-56.6% of DKD patients with estimated glomerular filtration rate (eGFR) < 60 ml/min per 1.73 m² are normoalbuminuric. Thus, urinary biomarkers of nonalbuminuric renal insufficiency in type 2 diabetes mellitus (T2DM) patients are urgently needed.

Methods

This cross-sectional study enrolled 209 T2DM patients with normoalbuminuria whose diabetes duration was more than 5 years. The patients were classified into two groups, NO-CKD (eGFR ≥ 60 ml/min per 1.73 m², n = 165) and NA-DKD (eGFR < 60 ml/min per 1.73 m², n = 44). Levels of urinary neutrophil gelatinase-associated lipocalin (NGAL), retinol-binding protein (RBP), plasminogen activator inhibitor-1 (PAI-1), vascular cell adhesion molecule-1 (VCAM-1), and E-cadherin were detected, and their correlations with eGFR, plasma TNF-α, IL-6, endothelin-1 (ET-1), and 8-hydroxydeoxyguanosine (8-OHdG) were assessed.

Results

Among patients with renal insufficiency, 26.0% was normoalbuminuric. Compared to the NO-CKD group, the NA-DKD group was older with lower hemoglobin (HB) levels and higher systolic blood pressure (SBP), plasma TNF-α, IL-6, and 8-OHdG levels. Logistic regression analysis suggested that age, TNF-α, and 8-OHdG were independent risk factors for nonalbuminuric renal insufficiency. Compared to the NO-CKD group, the NA-DKD group exhibited significant increases in urinary NGAL and RBP levels but not PAI-1, VCAM-1, and E-cadherin. Urinary NGAL and RBP both correlated negatively with eGFR and positively with plasma IL-6 and 8-OHdG. Multiple linear regression indicated NGAL (β = -0.287, p = 0.008) and RBP (β = -44.545, p < 0.001) were independently correlated with eGFR.

Conclusion

Age, plasma TNF-α, and 8-OHdG are independent risk factors for renal insufficiency in T2DM patients with normoalbuminuria. Urinary NGAL and RBP can serve as noninvasive biomarkers of normoalbuminuric renal insufficiency in T2DM.

5-Hydroxyhexanoic Acid Predicts Early Renal Functional Decline in Type 2 Diabetes Patients with Microalbuminuria

Background/Aims: Diabetic nephropathy (DN) is a leading cause of end-stage renal disease. Microalbuminuria (MA) is widely used to predict early progressive renal function decline (ERFD) of DN in type 2 diabetes mellitus (T2D) patients, but the sensitivity and specificity of MA have been questioned. Here, we determined the urine metabolites differences between T2D patients with MA who maintained stable renal function and those who progressed to ERFD in order to identify specific biomarkers of the progression of renal dysfunction. Methods: A total of 102 T2D patients with MA and normal renal function at baseline were followed up for 5–6 years. Of these, 52 patients were selected and classified into two groups according to the later renal function; 25 patients who experienced ERFD were regarded as the progressive group, while 27 patients who maintained stable renal function were considered as the stable group. In the pilot study, untargeted, broad-spectrum urine metabolomics was performed on the urine of 12 subjects from the progressive group (5 patients as “progressors”) and stable group (7 patients as “non-progressors”) to discover candidate markers. We then used a targeted metabolomics analysis to identify the selected markers in the urine of an additional 40 patients (20 from the progressive group as cases, and 20 from the stable group as controls) in the validation study. Results: A total of 318 known metabolites were detected in the pilot study and 6 metabolites with significant difference between progressors and non-progressors were identified. The levels of 4 metabolites, including azelaic acid, adipic acid, 5-hydroxyhexanoic acid, and L-tryptophan decreased significantly, while levels of L-pyroglutamic acid and D-norvaline increased observably in the progressors compared with non-progressors. Furthermore, in the validation study, 6 metabolites were confirmed by quantitative measurements and their concentrations were consistent with the changes in the pilot study. Concentrations of L-pyroglutamic acid and D-norvaline still increased in the cases, but were not statistically significant. Of the 4 metabolites with decreased concentrations among the cases, only 5-hydroxyhexanoic acid remained statistically significant while the other 3 metabolites did not differ between cases and controls. Conclusion: We have identified urine metabolites and shown that 5-hydroxyhexanoic acid can be used as a predictor of progression of ERFD in T2D patients with MA. This finding provides the new perspective that 5-hydroxyhexanoic acid may be useful to identify T2D patients with MA who are at risk of ERFD.

MicroRNAs in the Progress of Diabetic Nephropathy: A Systematic Review and Meta-Analysis

Background

We conducted a systematic review and meta-analysis of existing literature to evaluate the different outcomes of microRNAs (miRNAs) in diabetic nephropathy (DN), including urinary albumin excretion rates, urinary albumin creatinine rates, glomerular filtration rate, HbAc1, and creatinine.

Methods

Electronic databases including PUBMED, MEDLINE, and EMBASE were searched for eligible publications to July 2018. The following comparisons between treatment groups were included: normal group versus DN group; control group versus micro/macroalbuminuria group.

Results

Twelve eligible studies that included 2500 participants were finally recruited in this meta-analysis. Fifteen miRNAs (miRNA-21, miRNA-181b, miRNA-194, miRNA-30, miRNA-215, and others) were upregulated whereas seven miRNAs (miRNA-26a, miRNA-126, miRNA-424, miRNA-574-3p, miR-223, miR-155, and miR-192) were downregulated in the DN group compared with control groups. The miR-133b, miR-342, miR-30, miR-192, miR-194, and miR-215 were significantly correlated in urinary albumin excretion rates (r=0.33, 95% CI= 0.26-0.39). miR-192, miR-217, miR-15b, miR-34a, and miR-636 were correlated with urinary albumin creatinine rates (r=0.69; 95% CI=0.12-0.92), while miR-133b, miR-345, miR-33, miR-326, miR-574-3p, miR-126, miR-217, miR-15b, miR-34a, and miR-636 were significantly correlated with HbAc1 (r =0.23, 95% CI = 0.15-0.31). There were twelve miRNAs that were closely related to the glomerular filtration rate (r=0.28, 95% CI =0.21-0.34). Creatinine (r=0.33, 95% CI = 0.22-0.40) was significantly different between normal and DN groups.

Conclusions

The meta-analysis acquired the correlations between miRNAs and outcomes including UAER, UACR, eGFR, HbAc1, and creatinine in DN. It suggested that miRNAs may participate in the pathogenesis of DN process.

The Correlation between Serum Uric Acid and Renal Function in Elderly Chinese Diabetes with Normoalbuminuria

OBJECTIVE

The elder diabetic patients increases rapidly in China and often accompany with hyperuricemia. Recently evidences show that renal function has been impaired in part of diabetic patients with normoalbuminuria. Therefore, we investigated the relationship between serum uric acid (SUA) and renal function in Chinese elder diabetes with normoalbuminuria.

METHODS

The physical examination data from 1052 cases of diabetic residents with normoalbuminuria aged 70 years and over in the Jiangchuan community of Minhang District, Shanghai, from October 2011 to September 2014 was analyzed retrospectively. Each received height, body weight, waist circumference (WC), waist-to-hip ratio (WHR), blood pressure (BP), and collected samples of fasting blood and morning urine to detect blood routine, blood glucose, glycosylated hemoglobin (HbA1c), blood lipids, serum creatinine, urinary albumin, urine creatinine, and urine PH value. Correlation between SUA and renal function, an index of which is estimated using estimated glomerular filtration rate (eGFR), was analyzed.

RESULTS

The prevalence of hyperuricemia was 21.10%. Levels of WC and triglyceride (TG) increased and the levels of HbA1c, high density lipoprotein-cholesterol (HDL-C), eGFR, and urine PH decreased while the levels of SUA increased. Moreover, negative correlation of eGFR with age, WC, leukocyte, and SUA (Pearson r=0.415) was observed via Pearson correlation analysis. It indicates the strong association between SUA and eGFR. Furthermore, eGFR independently associated with SUA, age, leukocyte, hemoglobin (Hb), and fasting blood glucose (FBG) was confirmed by multiple linear stepwise regression analysis.

CONCLUSION

SUA may play an important role in the decrease of eGFR in elderly Chinese diabetic patients with normoalbuminuria.

The Kidney Specific Protein myo-Inositol Oxygenase, a Potential Biomarker for Diabetic Nephropathy

BACKGROUND/AIMS

Renal tubular injury plays an important role in the progression of diabetic nephropathy (DN). However, there is a lack of specific biomarkers for tubular damage in incipient DN. We have evaluated the role of myo-inositol oxygenase (MIOX) in the tubular injury of DN, but whether it could serve as a new biomarker for the early diagnosis of DN is unclear.

METHODS

Ninety patients with type 2 diabetes mellitus (T2DM) were divided into normoalbuminuria, microalbuminuria and macroalbuminuria groups. Fifteen patients from the last group were pathologically diagnosed as type 2 DN (T2DN), and fifteen patients with minimal change disease served as a control group. The expression of MIOX and silent information regulator 1 (Sirt1) in renal biopsies was determined by immunohistochemistry (IHC), and serum/urine MIOX, Sirt1, KIM-1 and NGAL were measured using enzyme-linked immunosorbent assays (ELISAs). Spearman's correlation and multiple regression analyses were carried out for statistical analyses.

RESULTS

Compared with the controls, MIOX expression was significantly increased in the renal tissues of T2DN patients, and was positively correlated with tubulointerstitial lesions and renal ROS production but inversely correlated with Sirt1 expression. In addition, the serum and urine MIOX were significantly increased and gradually elevated with the increasing of UACR. Interestingly, elevated MIOX levels in serum and urine were found in diabetic patients without early signs of glomerular damage (normoalbuminuric group). Further multivariate regression analysis showed that sMIOX and uMIOX correlated significantly with HbA1c, serum creatinine and logUACR, respectively.

CONCLUSION

These data indicate that increased MIOX expression in the kidney contributes to tubular damage in DN. The concentration of MIOX in the serum and urine may serve as a new biomarker for the early diagnosis of DN.

Rapid decline of kidney function in diabetic kidney disease is associated with high soluble Klotho levels

BACKGROUND

Klotho is found in two forms: a transmembrane form and a soluble form (s-Klotho). In order to be excreted, s-Klotho, that is too large to be filtered, will probably reach the proximal convoluted tubule by a transcytosis process. The aim of our study was to show the relationship between the levels of s-Klotho and tubular injury in patients with diabetic kidney disease (DKD), using as tubular injury marker the kidney injury molecule-1 (KIM-1).

METHODS

Our study included 63 DKD patients (stages 1-5, mean eGFR 65.15±32.45ml/min) with a mean age 58.13±12 years. In all patients we determined serum levels of: KIM-1 and s-Klotho using ELISA, urinary albumin/creatinine ratio (UACR) and reduction in the estimated glomerular filtration rate (eGFR) per year.

RESULTS

We found a strong statistically significant correlation of s-Klotho with the rate of reduction of eGFR/year (r=0.714, p=0.0004) and with the tubular injury marker KIM-1 (r=0.758, p=0.005) and strong correlations of UACR with the rate of reduction of eGFR/year (r=0.53, p<0.01), KIM-1 (r=0.49, p<0.05) and s-Klotho (r=0.52, p<0.01).

CONCLUSION

Despite previous published data, that shows a decrease of s-Klotho in chronic kidney disease, in our study the rapid annual decline of kidney function but not the level of eGFR was associated with increased s-Klotho. A possible explanation could be a more severe proximal tubule injury that could lead to a reduction of tubular excretion of s-Klotho as suggested by the correlation of s-Klotho levels with the serum levels of KIM-1.

Clinical predictive biomarkers for normoalbuminuric diabetic kidney disease

AIMS

A portion of patients with diabetes mellitus follow the progression of a non-albuminuria-based pathway; i.e., normoalbuminuric diabetic kidney disease (NA-DKD). However, the risk factors which determine NA-DKD are not yet fully understood. This cross-sectional study was therefore aimed to investigate the association between various biomarker levels and estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes mellitus and normoalbuminuria (T2D-NA).

METHODS

We measured cardiovascular disease (CVD) [serum osteoprotegerin (OPG), plasma brain natriuretic peptide (BNP), cardio-ankle vascular index (CAVI)], tubular damage [urinary L-type fatty acid binding protein (L-FABP)], and inflammatory [serum tumornecrosis factor (TNF) α and its receptors (TNFRs)] biomarkers in 314 patients with T2D-NA.

RESULTS

The biomarkers of CVD and inflammation showed a significant negative correlation with eGFR. In a logistic multivariate model, none of the biomarkers, except TNFα and TNFRs, were associated with reduced renal function (eGFR < 60 mL/min/1.73 m²) after adjustment for possible biological and clinical covariates. However, the association observed in TNFα was lost after adjusting for TNFR and other covariates.

CONCLUSIONS

In patients with T2D-NA, elevated levels of circulating TNFRs, but not of TNFα, were strongly associated with reduced renal function, independently of all relevant covariates.

The relationship between the thickness of glomerular basement membrane and renal outcomes in patients with diabetic nephropathy

AIMS

Glomerular basement membrane (GBM) thickening is considered as one of the earliest detectable pathological features of diabetic nephropathy (DN). However, whether the thickness of GBM will impact the prognosis of DN remains largely unknown. Our aim was to explore the relationship between thickness of GBM and DN progression in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 118 patients with T2DM and biopsy-proven DN who received follow-up for at least 1 year were recruited. The patients were divided into two groups according to the median (787 nm) of the GBM thickness: Group 1: GBM thickness < 787 nm (n = 59), and Group 2: GBM thickness ≥ 787 nm (n = 59). The GBM width was estimated by the direct GBM measurements as recently modified by Haas. Renal outcomes were defined by progression to ESRD and/or doubling of serum creatinine (D-Cr). The influence of GBM thickness on renal outcomes was assessed using Cox regression.

RESULTS

Compared with the Group 1, patients in Group 2 had more serious renal insufficiency and glomerular lesions. During the follow-up, ESRD occurred in 39.8% of patients, and 8.5% of patients progressed to D-Cr. The univariate analysis indicated the greater width of GBM the higher risk of renal outcomes in T2DM patients with DN (HR [95% CI] = 2.180 [1.246-3.814], p = 0.006). However, the multivariate COX analysis demonstrated that the GBM thickness was not an independent risk factor for progression to ESRD or D-Cr (HR [95% CI] = 0.825 [0.404-1.685], p = 0.597) when adjusting for important clinical variables and pathological findings.

CONCLUSIONS

In conclusion, the DN patients with greater width of GBM had relatively poorer renal prognosis, although it did not emerge as an independent indicator of disease progression.

Clinico-pathological features of kidney disease in diabetic cases

Diabetic kidney disease is the major cause of end-stage kidney disease in developed countries. However, the onset of kidney disorder and the progression pattern of kidney dysfunction and proteinuria greatly vary cases by cases. Therefore, risk classification with clinical data and pathological findings is important. Recent clinico-pathological study with kidney biopsy samples from diabetic patients revealed that pathological changes of diabetic nephropathy are characteristic and have special impacts on prognosis in each clinical stage. Moreover, comparison of the clinico-pathological findings of diabetic nephropathy with hypertensive nephrosclerosis revealed that there are few differences in their pathological findings in cases with low albuminuria and preserved estimated glomerular filtration rate (eGFR). Because it is so difficult to clearly distinguish pure kidney lesions caused by diabetes and kidney lesions due to effects other than diabetes, it is vital that these overlapped pathological findings be confirmed on kidney biopsy in cases of early stage diabetes. Further research is warranted regarding the pathogenesis of diabetic nephropathy and indication of kidney biopsy in diabetic cases.

Critical Shear Stress is Associated with Diabetic Kidney Disease in Patients with Type 2 Diabetes

Critical shear stress (CSS, mPa) is an index of red blood cell (RBC) aggregability, defined as the minimal shear stress required to disperse RBC aggregates. This study aimed to investigate the association between CSS and the risk of diabetic kidney disease (DKD). A total of 421 (mean age, 58.1 ± 11.5 years; male, 250) individuals with T2DM were enrolled and divided into three groups according to CSS level. CSS was measured using a transient microfluidic technique. DKD was defined as a glomerular filtration rate (GFR) <60 ml/min/1.73 m2 or a urine albumin-to-creatinine ratio (uACR) ≥30 mg/g. CSS was significantly higher in patients with DKD than in those without (317.43 ± 125.11 vs 385.22 ± 182.89, p < 0.001). Compared to the lowest CSS tertile, the highest CSS tertile was independently associated with the risk of DKD after adjusting for age, sex, duration of diabetes, presence of hypertension and haemoglobin. The cut-off value of CSS for DKD was approximately 310 mPa. These results suggest that haemorheologic changes may contribute to DKD, and further prospective studies are warranted to determine the role of CSS as a DKD screening tool.

Gut Microbiota-Dependent Trimethylamine-N-oxide and Serum Biomarkers in Patients with T2DM and Advanced CKD

Trimethylamine-N-oxide (TMAO) is a product of dietary, gut microbiome, and tissues metabolism. Elevated blood TMAO levels are associated with heart attack, stroke and chronic kidney disease (CKD). The purpose of our study was to investigate the gut microbiota associated with trimethylamine (TMA) production, the precursor of TMAO, and the serum levels of TMAO and inflammatory biomarkers associated with type 2 diabetes mellitus (T2DM) and CKD. Twenty adults with T2DM and advanced CKD and 20 healthy adults participated in the study. Analyses included anthropometric and metabolic parameters, characterization of TMA producing gut microbiota, and concentrations of TMAO, lipopolysaccharides (LPS) endotoxin, zonulin (Zo) gut permeability marker, and serum inflammatory and endothelial dysfunction biomarkers. Diversity of the gut microbiota was identified by amplification of V3-V4 regions of the 16S ribosomal RNA genes and DNA sequencing. TMAO was quantified by Mass Spectrometry and serum biomarkers by ELISA. The significance of measurements justified by statistical analysis. The gut microbiome in T2DM-CKD patients exhibited a higher incidence of TMA-producing bacteria than control, p < 0.05. The serum levels of TMAO in T2DM-CKD patients were significantly higher than controls, p < 0.05. TMAO showed a positive correlation with Zo and LPS, inflammatory and endothelial dysfunction biomarkers. A positive correlation was observed between Zo and LPS in T2DM-CKD subjects. An increased abundance of TMA-producing bacteria in the gut microbiota of T2DM-CKD patients together with excessive TMAO and increased gut permeability might impact their risk for cardiovascular disease through elevation of chronic inflammation and endothelial dysfunction.