Markers of and Risk Factors for the Development and Progression of Diabetic Kidney Disease

Rationale and Strategies for Early Detection and Management of Diabetic Kidney Disease

Background and Aims Diabetic kidney disease (DKD), occurs in 20–40% of patients with diabetes mellitus (DM), is the leading cause of end-stage renal disease (ESRD). DKD is a clinical diagnosis mainly based on the persistent albuminuria and reduced estimated glomerular filtration rate (eGFR) [1]. However, increased UACR and reduced eGFR are the final consequences due to DKD, novel biomarkers are critical for predicting DKD development. Osteopontin (OPN) is a profibrotic adhesion phosphoprotein that participates in cell chemotaxis, adhesion, migration, and proliferation, as well as extracellular matrix (ECM) hyperplasia. Hyperglycemia could enhance OPN gene expression through the activation of the renin-angiotensin system (RAS), mTOR pathway, NF-κB, and TGF-β pathway and then cause podocyte injury and ECM hyperplasia. Therefore, OPN upregulation is not only the result of various pathophysiological processes in DKD, but also results in kidney injury. Osteopontin (OPN) could predict incident DKD in DM patients [2], N-terminal OPN (ntOPN) has a stronger profibrotic adhesion effect than full-length OPN. This study aims to reveal the clinical benefit of ntOPN as a potential marker to identify DM patients at high risk of DKD, and establish ntOPN-based diagnostic and forecast models for renal outcomes in DM patients. Method We performed a cross-sectional study of 316 adults with Type 1 DM≥ 5 years or Type 2 DM, then followed by a prospective observational cohort study of 143 adult DM patients without renal involvement at baseline and follow-up for at least one year. During the follow-up period, the primary endpoint was “DKD occurrence”, defined as the presence of one of the following conditions in DM patients [3]: (1) repeat UACR ≥30 mg/g at least 2 of 3 measurements within 3 to 6 months; (2) eGFR <60 mL/min/1.73 m2 for more than three months; (3) renal pathological findings were consistent with DKD. The secondary endpoint was “DKD progression”, which included: (1) eGFR sustained decreased by at least 25%; (2) development of ESRD, and/or need for renal replacement therapy; (3) death from the renal cause. Logistic regression analysis was performed to analyze the relationship between parameters and the events of DKD occurrence and progression. Receiver operator characteristic (ROC) analysis was used to assess the predictive ability of established models for clinical endpoints. Results The median value of urinary ntOPN (UntOPN) was 44.15 ng/ml in the cross-sectional cohort, DKD prevalence was significantly higher in the high UntOPN group than in the low UntOPN group. The ROC curves of UntOPN, urinary neutrophil gelatinase-associated lipocalin (UNGAL), and their combination indicated that both combination and ntOPN alone perform better than UNGAL for DKD diagnosis (Fig. 1A). In the prospective cohort, UntOPN was an independent risk factor and further improved the predictive ability for DKD occurrence and DKD progression than UNGAL (Figs. 1B and 1C). Based on the parameters detected as risk factors for DKD occurrence and progression, we set up a series of multi-biomarker panels for DKD prediction using UntOPN, UNGAL, serum cystatin C, serum creatinine (Scr), UACR, and TCH/HDL-C ratio. Compared with the model of Scr + UACR, the area under ROC curve (AUC) of the six-biomarker model was higher, and also ranked the highest among the six ROC curves in predicting 1-year risk of DKD occurrence and DKD progression (Figs. 1B and 1C). Conclusion Our results showed that urinary ntOPN is associated with DKD development, and elevated urinary ntOPN is an independent predictor for DKD occurrence and progression. Compared with the traditional biomarkers of Scr + UACR, our multi-biomarker models based on urinary ntOPN performed better in predicting DKD development, which could provide more accurate tools for DKD risk prediction, thereby improving the renal prognosis in DM patients.

Clinical Challenges in Diagnosis and Management of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease (ESKD) in the Western world. Better control of glycemia and blood pressure, including renin-angiotensin system blockade (RASB), appear to have slowed DKD progression rate but have been unable to substantially decrease the annual incidence of new cases of DKD related ESKD. Thus, new treatment targets are needed. Higher levels of serum uric acid (SUA) have been associated with increased risk and progression of DKD in persons with types 1 (T1D) and 2 (T2D) diabetes and of chronic kidney disease (CKD) in general. This review presents the epidemiological, clinical, and clinical trial evidence regarding the hypothesis that SUA reduction could slow progression of DKD and/or CKD in general.

Introduction. Elevated serum uric acid levels are associated with the progression of kidney disease in patients with type 2 diabetes mellitus (DM), through mechanisms involving endothelial dysfunction, oxidative stress, and chronic inflammation. Research in Indonesia on the relationship between uric acid levels and the decline of glomerular filtration rate (GFR) in diabetic patients remains limited. This study aimed to determine the association between serum uric acid (SUA) levels and decline in glomerular filtration rate among patients with diabetes mellitus diagnosed with diabetic kidney disease at Cipto Mangunkusumo Hospital, Jakarta, over a one-year period. Methods. This retrospective cohort study analyzed medical records of 192 type 2 diabetes melitus patients attending the Endocrinology and or Kidney Hypertension Clinics at Cipto Mangunkusumo National General Hospital , Jakarta. Inclusion criteria were baseline glomerular filtration rate ≥60 mL/min/1.73 m², available baseline serum uric acid, and follow-up glomerular filtration rate after one year. Bivariate and multivariate analyses were performed, adjusting for confounders including age, sex, hypertension, body mass index (BMI), triglycerides, HDL, LDL, total cholesterol, HbA1c, fasting blood glucose, and albuminuria. Results. Hyperuricemia prevalence was 85.94%. Multivariate analysis revealed that elevated SUA levels (≥6 mg/dL in women, ≥7 mg/dL in men) were associated with a 13.5% higher risk of GFR decline compared to normal serum uric acid (RR 1.135; 95% CI 1.015–1.268) after adjustment. Higher Body mass index was protective against glomerular filtration rate decline, while lipid profile, HbA1c, and fasting blood glucose were not significantly associated with diabetic kidney disease progression. Conclusions. Hiperuricemia is an independent risk factor for diabetic kidney disease progression in type 2 diabetes mellitus. Regular monitoring and management of serum uric acid may be crucial in preventing kidney function decline in this population.

Aggressive blood pressure reduction and renin–angiotensin system blockade in chronic kidney disease: time for re-evaluation?

Role of Kidney Biopsies for Biomarker Discovery in Diabetic Kidney Disease.

BACKGROUND AND OBJECTIVES:One out of five Saudi diabetics develops end-stage renal disease (ESRD). Factors associated with progressive loss of renal function have not been extensively studied and reported in our community. We sought to evaluate the pattern and progression in glomerular filtration rate (GFR) and investigate the potential risk factors associated with progression to diabetic nephropathy (DN) among Saudi patients.DESIGN AND SETTING:Hospital-based retrospective analysis of type 2 diabetic patients seen between January 1989 and January 2004 at Security Forces Hospital and King Saud University in Riyadh, Saudi Arabia.PATIENTS AND METHODS:DN was defined as persistent proteinuria assessed by urine dipstick [at least twice for at least two consecutive years and/or serum creatinine >130 μmol/L; and/or GFR <60 mL/min/1.73m2].RESULTS:Of 1952 files reviewed, 621 (31.8%) met the criteria for DN, and 294 (47%) were males. The mean (SD) age of the patients at baseline was 66.9 (11.4) years, and mean duration of diabetes was 15.4 (7.5) years. GFR deteriorated from a baseline value of 78.3 (30.3) mL/min/1.73m2 to 45.1 (24.1) mL/min/1.73m2 at the last visit, with a mean rate of decline in GFR of 3.3 mL/min/year. Progression of nephropathy was observed in 455 (73.3%) patients, with 250 (40.3%) patients doubling their first–hospital-visit serum creatinine level in a mean of 10.0 (6.0) years. At the end of the study, 16.5% of the cohort developed ESRD and were dialyzed. GFR >90 mL/min/1.73m2 at the first hospital visit; duration of diabetes >10 years; persistent proteinuria; systolic blood pressure >130 mm Hg; and presence of retinopathy were significant markers associated with progression of nephropathy.CONCLUSION:Diabetic nephropathy tends to be progressive among Saudis, with GFR deteriorating at a rate of 3.3 mL/year and with a doubling of serum creatinine level in 40.3% of patients in 9.9 years.

Measuring urinary tubular biomarkers in type 2 diabetes does not add prognostic value beyond established risk factors

IntroductionThe balance of trace elements plays an important role in diabetic kidney disease (DKD) patients. However, studies on the differences in urinary trace elements across different DKD stages are scarce....

ObjectiveWe investigated the relationship between thyroid hormones and the risk of diabetic kidney disease (DKD) progression.MethodsA total of 452 patients with type 2 diabetes were included, and a cross-sectional analysis was performed. Urine albumin/creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) were used to diagnose persistent albuminuria and stage chronic kidney disease, respectively. The Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline was used to describe the risk of DKD progression (low, moderate, and high or very high risks).ResultsThe DKD group had higher levels of thyroid-stimulating hormone (TSH) and lower levels of free triiodothyronine (FT3) and free thyroxine (FT4) than the non-DKD group. The prevalence of thyroid dysfunction in the DKD group was significantly higher than in the non-DKD group, especially the prevalence of subclinical hypothyroidism. FT3 levels decreased gradually with the deterioration of DKD. TSH levels increased with an increasing KDIGO category. FT3 and FT4 levels were negatively correlated with serum creatinine levels and ACR, and positively correlated with eGFR. Contrastingly, TSH was positively correlated with ACR, and negatively correlated with eGFR. After adjustment, an increase in FT3 levels significantly reduced the risk of DKD [odds ratio, OR (95% confidence interval, CI)=0.58 (0.42–0.79)] and DKD progression [ORs (95% CIs)=0.65 (0.45–0.93) for the moderate risk group and 0.50 (0.33–0.74) for the high or very high-risk group, using the low-risk group as a reference]. FT3 levels below 4.30 pmol/L in men and 3.99 pmol/L in women were the cut-off points for an increased risk of DKD progression.ConclusionLow FT3 level is an independent risk factor for DKD and DKD progression. FT3 ≤4.30 pmol/L in men and ≤3.99 pmol/L in women will greatly increase the risk of kidney disease progression in patients with type 2 diabetes.

Type 2 diabetes mellitus (T2DM) is a highly heterogeneous disease with a varying risk of complications. The recent novel subgroup classification using cluster analysis contributed to the risk evaluation of diabetic complications. However, whether the subgroup classification strategy could be adopted to predict the risk of onset and progression of diabetic kidney disease (DKD) in Chinese individuals with T2DM remains to be elucidated. In this retrospective study, 612 Chinese patients with T2DM were enrolled, and the median follow-up time was 3.5years. The T2DM subgroups were categorized by a two-step cluster analysis based on five parameters, including age at onset of diabetes, body mass index (BMI), glycosylated hemoglobin (HbA1c), homeostasis model assessment 2 of insulin resistance (HOMA2-IR), and homeostasis model assessment 2 of β-cell function (HOMA2-β). Clinical characteristics across subgroups were compared using t-tests and chi-square tests. Furthermore, multivariate logistic regression models were adopted to assess the risk of albuminuria progression and renal function decline among different subgroups. The cohort was categorized into four groups: severe insulin-deficient diabetes (SIDD), with 146 patients (23.9%); mild insulin resistance (MIRD), with 81 patients (13.2%); moderate glycemic control diabetes (MGCD), with 211 patients (34.5%); and moderate weight insulin deficiency diabetes (MWIDD), with 174 patients (28.4%). The MIRD group exhibited an increased risk of progression from non-albuminuria to albuminuria as compared with the MWIDD group, with an adjusted odds ratio (OR) and 95% confidence interval (CI) of 2.92 (1.06, 8.04). The SIDD group had a higher risk of progression from micro-albuminuria to macro-albuminuria as compared with the MGCD group, with an adjusted OR and 95% CI of 3.39 (1.01, 11.41). There was no significant difference in the glomerular filtration rate (GFR) decline among all groups. The present study offered the first evidence for risk evaluation of the development of DKD in the novel cluster-based T2DM Chinese subgroups. It suggested that the MIRD subgroup had a higher risk of DKD onset than the MWIDD subgroup. Meanwhile, the SIDD subgroup showed a higher risk of progression of albuminuria than the MGCD subgroup. This novel classification system could be effective in predicting the risk of DKD in Chinese patients with T2DM, which could facilitate the implementation of personalized therapeutic strategies. This study was registered in the Chinese Clinical Trial Registry (ChiCTR2300077183).

Renin-Angiotensin System Blockade in Advanced Kidney Disease: Stop or Continue?

Diabetic kidney disease (DKD), also known as diabetic nephropathy, is the leading cause of renal impairment and end-stage renal disease. Patients with diabetes are at risk for DKD because of poor control of their blood glucose, as well as nonmodifiable risk factors including age, ethnicity, and genetics. This genome-wide association study (GWAS) was conducted for the first time in the Emirati population to investigate possible genetic factors associated with the development and progression of DKD. We included data on 7,921,925 single nucleotide polymorphism (SNPs) in 258 cases of type 2 diabetes mellitus (T2DM) who developed DKD and 938 control subjects with T2DM who did not develop DKD. GWAS suggestive results (P < 1 × 10–5) were further replicated using summary statistics from three cohorts with T2DM-induced DKD (Bio Bank Japan data, UK Biobank, and FinnGen Project data) and T1DM-induced DKD (UK-ROI cohort data from Belfast, UK). When conducting a multiple linear regression model for gene-set analyses, the CNR2 gene demonstrated genome-wide significance at 1.46 × 10–6. SNPs in CNR2 gene, encodes cannabinoid receptor 2 or CB2, were replicated in Japanese samples with the leading SNP rs2501391 showing a Pcombined = 9.3 × 10–7, and odds ratio = 0.67 in association with DKD associated with T2DM, but not with T1DM, without any significant association with T2DM itself. The allele frequencies of our cohort and those of the replication cohorts were in most cases markedly different. In addition, we replicated the association between rs1564939 in the GLRA3 gene and DKD in T2DM (P = 0.016, odds ratio = 0.54 per allele C). Our findings suggest evidence that cannabinoid signalling may be involved in the development of DKD through CB2, which is expressed in different kidney regions and known to be involved in insulin resistance, inflammation, and the development of kidney fibrosis.

Background and Aims Diabetic kidney disease (DKD) represents one of the major causes of end stage kidney disease worldwide. Despite DN having such a high incidence, mouse models of DN rarely mimic all aspects of the human disease, besides showing very slow progression and sometimes maintenance issues. For this reason, in this project we aimed to develop an accelerated, reproducible and accessible mouse model of DN. Method For our experiments we chose 9-week-old female and male of the leptin receptor knock-out (BKS.Cg-Dock7m +/+ Leprdb/J) mice as type 2 diabetes model. As these mice are still not prone to develop severe kidney injury despite their diabetic condition, we administered the eNOS inhibitor L-NAME for 6 weeks, in order to suppress nitric oxide production and therefore to aggravate kidney damage. Mice were divided in three groups: one vehicle control group, one receiving 40/mg/kg/day of L-NAME and one receiving 80/mg/kg/day of L-NAME dissolved in drinking water. Blood pressure and glomerular filtration rate (GFR) were measured at different time points, together with glycemia and albuminuria. Weight and water intake were also monitored throughout the study. At the end of the experiment, animals were killed and blood and organs collected for further analysis. Results Mice treated with 80 mg/kg/day of L-NAME showed an average increase of 10 mmHg in systolic blood pressure, with a peak of 30 mmHg increase at week 4 of treatment. On the other hand, 40 mg/kg/day of L-NAME did show any effect on blood pressure. Despite the different effect on blood pressure, three weeks of L-NAME administration caused a significant reduction in GFR at both doses, with 5% reduction for the 40 mg-group and 23% for the 80 mg-group. For the 80 mg-group we observed an even further GFR decline after 5 weeks of treatment, with a 28% reduction. No change in GFR was observed in the controls. This decrease in GFR was accompanied by a 10-fold increase in urinary albumin for both experimental groups already after 3 weeks of treatment, which after 4 weeks slightly declined but remained significantly higher than the controls (p &amp;lt; 0.0001). At a histological level, PAS staining of kidney sections revealed that in particular mice treated with 80 mg of L-NAME have enlarged Bowman capsule and glomerular tuft area, besides a reduced glomerular capillary density, coinciding with mesangial expansion. We also stained for overall collagen deposition with picrosirius red staining in order to detect possible fibrosis formation. We then observed that 80 mg of L-NAME accelerates interstitial fibrosis in the cortical area of the kidney, which also overlapped with an increased deposition of collagen I. This increase in collage I was also detected in kidney cortex of mice treated with 40 mg of L-NAME, although their overall collagen deposition and therefore fibrotic tissue did not differ from the control group. The medullar region of kidneys was also analyzed, but none of the two experimental groups revealed significant differences in terms overall collagen or collagen I deposition. Unlike mesangial expansion and fibrosis, L-NAME did not influence microphages infiltration, as revealed by CD68 staining in kidney sections. This suggests that L-NAME treatment does not accelerate kidney damage by triggering or accelerating inflammatory processes. This was also confirmed by qPCR analysis of kidney tissue, where the expression pro-inflammatory markers, such as IL1β, TNFα and MCP-1, did not change in the experimental groups. Conclusion Our results show that L-NAME considerably accelerates the progression of DKD in diabetic mice, with GFR declining and progressive albuminuria already after 3 weeks. Such disfunction is confirmed at 6 weeks by histological analysis, where mesangial expansion and fibrosis were detected. This model can be used to assess the therapeutic potential of novel interventions aimed to slow down DKD.