Validation of the interstitial fibrosis and tubular atrophy on the new pathological classification in patients with diabetic nephropathy: A single-center study in China

Glomerular crescents are associated with the risk of type 2 diabetic kidney disease progression: a retrospective cohort study

BACKGROUND

Diabetic kidney disease (DKD) stands as the predominant cause of chronic kidney disease and end-stage kidney disease. Its diverse range of manifestations complicates the treatment approach for patients. Although kidney biopsy is considered the gold standard for diagnosis, it lacks precision in predicting the progression of kidney dysfunction. Herein, we addressed whether the presence of glomerular crescents is linked to the outcomes in patients with biopsy-confirmed type 2 DKD.

METHODS

We performed a retrospective evaluation, involving 327 patients diagnosed with biopsy-confirmed DKD in the context of type 2 diabetes, excluding cases with other glomerular diseases, from nine tertiary hospitals. Hazard ratios (HRs) were calculated using a Cox regression model to assess the risk of kidney disease progression, defined as either ≥ 50% decrease in estimated glomerular filtration rates or the development of end-stage kidney disease, based on the presence of glomerular crescents.

RESULTS

Out of the 327 patients selected, ten patients had glomerular crescents observed in their biopsied tissues. Over the follow-up period (median of 19 months, with a maximum of 18 years), the crescent group exhibited a higher risk of kidney disease progression than the no crescent group, with an adjusted HR of 2.82 (1.32-6.06) (P = 0.008). The presence of heavy proteinuria was associated with an increased risk of developing glomerular crescents.

CONCLUSION

The presence of glomerular crescents is indeed linked to the progression of type 2 DKD. Therefore, it is important to determine whether there is an additional immune-mediated glomerulonephritis requiring immunomodulation, and it may be prudent to monitor the histology and repeat a biopsy.

Crescents, an Independent Risk Factor for the Progression of Type 2 Diabetic Kidney Disease

CONTEXT

Crescents have been noticed in pathologic changes in patients with diabetic kidney disease (DKD). However, the clinical significance of crescents is still not well recognized.

OBJECTIVE

The main objective was to investigate the association between crescents and the prognoses of type 2 DKD (T2DKD) patients, and, secondly, to analyze the relationship between crescents and clinicopathologic features.

METHODS

A retrospective cohort study of 155 patients with T2DKD diagnosed by renal biopsy was carried out in a single center. Clinicopathologic features of patients with or without crescents were analyzed. Cox regression models and meta-analysis were used to determine the prognostic values of crescents for T2DKD. A nomogram was constructed to provide a simple estimation method of 1, 3, and 5-year renal survival for patients with T2DKD.

RESULTS

Compared with T2DKD patients without crescents, patients with crescents had higher 24-hour proteinuria and serum creatinine levels, as well as more severe Kimmelstiel-Wilson (K-W) nodules, segmental sclerosis (SS), and mesangiolysis (all P < .05). Furthermore, the crescents were positively correlated with serum creatinine, 24-hour proteinuria, K-W nodules, SS, mesangiolysis, and complement 3 deposition. Multivariate Cox models showed that crescents were an independent prognostic risk factor for renal survival (hazard ratio [HR] 2.68, 95% CI 1.27-5.64). The meta-analyzed results of 4 studies on crescents in T2DKD confirmed that patients with crescents had a significantly higher HR for renal progression.

CONCLUSION

Patients with crescents in T2DKD have more severe clinicopathologic changes and worse prognoses. The crescent can serve as an independent risk factor for T2DKD progression.

Prognostic value of metabolic syndrome in renal structural changes in type 2 diabetes

PURPOSE

To investigate the prognostic value of metabolic syndrome (MetS) and its relationship with renal structure changes in patients with type 2 diabetes and associated diabetic nephropathy (DN).

METHODS

411 Chinese patients with type 2 diabetes and biopsy-confirmed DN were enrolled in this retrospective study. MetS was defined according to the modified criteria of the 2005 International Diabetes Federation. Baseline demographics and clinical information at the time of renal biopsy were extracted from the hospital's electronic medical records system. Renal pathological findings were assessed according to Renal Pathology Society system. Univariate and multivariate logistic regression analyses were performed to define the pathological covariates associated with MetS. A competing risk model, with death as the competing risk, was used to estimate the sub-distribution hazard ratio (SHR) of MetS for end-stage kidney disease (ESKD).

RESULTS

224 (55%) patients had MetS. Patients with MetS had poor renal function and more severe interstitial fibrosis tubular atrophy scores (IFTA) than those without MetS. Multivariate logistic regression analysis revealed that IFTA was significantly associated with MetS (odds ratio per score increase 1.45, 95% confidence interval [CI] 1.02-2.05). Of the patients with DN at risk, 40% of patients progressed to ESKD. After adjusting for renal function and pathological parameters, the presence of MetS was an independent predictor for progression to ESKD (SHR 1.93, 95% CI 1.34-2.79). The SHRs for progression to ESKD also increased as the number of MetS components increased. Additionally, adding the IFTA scores improved the prognostic power of a model that only contained MetS and clinical covariates for predicting future ESKD.

CONCLUSION

MetS is an independent prognostic predictor of ESKD in patients with T2D and DN, while adding the IFTA scores increased the prognostic value of MetS for renal outcome.

Identification and verification of vascular cell adhesion protein 1 as an immune-related hub gene associated with the tubulointerstitial injury in diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease (CKD) and end-stage renal disease (ESRD), but the pathogenesis is not completely understood. Tubulointerstitial injury plays critical roles in the development and progression of DKD. The present study aimed to investigate the profile of tubulointerstitial immune cell infiltration and reveal the underlying mechanisms between tubular cell injury and interstitial inflammation in DKD using bioinformatics strategies. First, xCell analysis identified immune cells displaying significant changes in the DKD tubulointerstitium, including upregulated CD4⁺ T cells, Th2 cells, CD8⁺ T cells, M1 macrophages, activated dendritic cells (DCs) and conventional DCs, as well as downregulated Tregs. Second, pyroptosis was identified as the main form of cell death compared with other forms of programmed cell death. Vascular cell adhesion protein 1 (VCAM1) was identified as the top ranked hub gene. The correlation analysis showed that VCAM1 was significantly positively correlated with pyroptosis and infiltrated immune cells in the tubulointerstitium. Upregulation of VCAM1 in the DKD tubulointerstitium was further verified in European Renal cDNA Bank cohort and was observed to negatively correlate with the glomerular filtration rate (GFR). Our in vitro study validated increased VCAM1 expression in HK-2 cells under diabetic conditions, and pyroptosis inhibition by disulfiram decreased VCAM1 expression, inflammatory cytokine release and fibrosis. In conclusion, our study identified upregulated VCAM1 expression in renal tubular cells, which might interact with infiltrated immune cells, thus promoting fibrosis. The FDA-approved drug disulfiram might improve fibrosis in DKD by targeting tubular pyroptosis and VCAM1 expression.

Renal histology in diabetic nephropathy predicts progression to end-stage kidney disease but not the rate of renal function decline

Background

While histopathologic changes correlate with functional impairment in cross-sectional studies of diabetic nephropathy (DN), whether these findings predict future rate of kidney function loss remains uncertain. We thus sought to examine the relationship between kidney histopathology, incidence of end-stage kidney disease (ESKD), and rate of estimated glomerular filtration rate (eGFR) loss in DN.

Methods

In this longitudinal cohort study, we studied 50 adults diagnosed with biopsy-proven DN. We analyzed the histopathologic parameters of each patient’s kidney biopsy, as defined by the Renal Pathology Society classification system for DN, and tracked all available eGFR measurements post-biopsy. We additionally collected baseline clinical parameters (at the time of biopsy), including eGFR, albumin-to-creatinine ratio (ACR), and hemoglobin A_1c. Multivariable linear regression was used to assess the relationship between histologic and clinical parameters at the time of the biopsy and eGFR slope. Kaplan-Meier curves and Cox regression were used to evaluate the association between histologic and clinical parameters and ESKD incidence.

Results

Progression to ESKD was associated with worsening interstitial fibrosis score (p = 0.05), lower baseline eGFR (p = 0.02), higher ACR (p = 0.001), and faster eGFR decline (p < 0.001). The rate of eGFR decline did not associate with any histologic parameter. Baseline ACR was the only studied variable correlating with eGFR slope (rho = − 0.41).

Conclusions

Renal histology predicts ultimate progression to ESKD, but not the rate of progression. Future work is required to identify novel predictors of rapid functional decline in patients with diabetic nephropathy.

Evaluation of Urinary Neutrophil Gelatinase Associated Lipocalin and Kidney Injury Molecule-1 as Diagnostic Markers for Early Nephropathy in Patients with Type 2 Diabetes Mellitus

PURPOSE

The purpose of this study was evaluating the early diagnostic value of two specific tubular markers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in diabetes nephropathy.

PATIENTS AND METHODS

Cross-sectional study was carried in three groups of patients from 10/2017 to 10/2018 in Military Hospital 103. Group I included 30 healthy peoples with estimated glomerular filtration rate (eGFR) >60 mL/min/1.73 m2 and urine albumin creatinine ratio (uACR) <30 mg/g. Group II included 30 type 2 diabetic patients having uACR <30 mg/g, eGFR >60 mL/min/1.73 m2. Group III included 30 type 2 diabetic patients having uACR >30 mg/g, eGFR >60 mL/min/1.73 m2.

RESULTS

Urine KIM-1 and NGAL increased progressively from control group (57.29 ± 25.91 pg/mL; 25.71 ± 13.69 ng/mL) to the group of diabetic patients with uACR <30 mg/g (167.06 ± 44.01 pg/mL; 37.42 ± 10.89 ng/mL) and the group of diabetic patients with uACR ≥30 mg/g) (p < 0.05). There were moderate correlations between KIM-1 (r = 0.48, p < 0.05) and NGAL (r = 0.45, p < 0.05) with uACR. There was a mild correlation between KIM-1 and NGAL (r = 0.29, p < 0.05). KIM-1 and NGAL are the independent tests to detect diabetic nephropathy. The sensivity and specificity of KIM-1 with cut-off value of 174.95 pg/mL were 62.37% and 73.48%, respectively; the sensivity and specificity of NGAL with cut-off value of 35.2 ng/mL were 60.45% and 70.37%, respectively.

CONCLUSION

KIM-1 and NGAL in urine are independent markers for early diagnostic diabetic nephropathy.

Effects of neutrophil-lymphocyte ratio on renal function and histologic lesions in patients with diabetic nephropathy

AIM

Chronic low-grade inflammation related to diabetic nephropathy (DN) may affect the serum neutrophil-lymphocyte ratio (NLR). We aimed to examine the cross-sectional relationships of NLR with renal function and structural lesions of DN in patients with type 2 diabetes mellitus (T2DM).

METHODS

The study retrospectively included 247 patients with T2DM and biopsy-proven DN. The severity of different pathological lesions was evaluated based on the criteria of Renal Pathology Society. The patients were divided into two groups based on the median (2.42) of NLR level, group 1: NLR < 2.42 (n = 122) and group 2: NLR ≥ 2.42 (n = 125). Renal dysfunction was defined by estimated glomerular filtration rate less than 60 mL/min per 1.73 m² . The influence of NLR on renal dysfunction was evaluated using logistic regression analysis.

RESULTS

The spearman's rank-correlation test indicted that NLR was positively correlated with interstitial fibrosis and tubular atrophy (r = 0.170, P = 0.007) and serum fibrinogen (r = 0.261, P < 0.001), whereas negatively related with estimated glomerular filtration rate (r = -0.233, P < 0.001). However, the NLR level demonstrated no association with glomerular lesions, interstitial inflammation and arteriolar hyalinosis. A multivariate logistic regression analysis showed that higher level of NLR (≥2.42) was significantly associated with renal dysfunction when adjusting for some important baseline clinical and pathological variables (odds ratio, 2.46; 95% confidence interval, 1.21-4.97; P = 0.012).

CONCLUSION

Increased NLR affects renal function and histologic lesions in patients with T2DM and may be an important factor for the progression of DN.

TLR4/NF-κB Signaling Induces GSDMD-Related Pyroptosis in Tubular Cells in Diabetic Kidney Disease

Gasdermin D (GSDMD) has been proven to be a key protein in the activation of pyroptosis. Pyroptosis of renal tubular epithelial cells contributes to the progression of tubular injury in kidney diseases. However, it remains elusive whether and how GSDMD is involved in the regulation of diabetic kidney disease (DKD). In this study, we found that tubular injury is accompanied by the up-regulation of Toll-like receptor 4 (TLR4) and GSDMD in patients with diabetic kidney disease. In addition, we discovered that the expressions of cleaved Caspase-1, active N-terminal fragments of GSDMD (GSDMD-NT), IL-18, and the secretion of IL-1β also increased in the kidneys of db/db mice. These changes were partially ameliorated following intraperitoneal injection of TAK-242, an inhibitor of TLR4. Similar results were observed in human tubular cells (HK-2) subjected to high-glucose (HG) conditions and treated with TAK-242 or parthenolide (inhibitor of NF-κB) by Western blot, Enzyme-linked immunosorbent assay (ELISA), and flow cytometry. These results indicated that TLR4/NF-κB signaling could induce GSDMD-mediated pyroptosis in tubular cells in DKD.

Functional Role of SUV39H1 in Human Renal Tubular Epithelial Cells Under High-glucose Ambiance

SUV39H1, the histone methyltransferase (HMTase) of histone H3 lysine 9 trimethylation (H3K9me3), is a known transcriptional repressor of inflammatory genes. The effect of SUV39H1 on inflammatory gene promoters under high-glucose stimulation in vascular smooth muscle cells (VSMCs), macrophages, and cardiomyocytes has been studied, but how SUV39H1 functions in renal tubules under diabetic conditions is unclear. Renal biopsy specimens of ten diabetic nephropathy (DN) subjects and seven non-DN minimal change diseases (MCD) subjects were collected. SUV39H1, IL-6, and MCP-1 expression in renal tissues were measured using immunohistochemical, while SUV39H1, H3K9me3, IL-6, and MCP-1 in human proximal tubular epithelial cells (HK-2) under varying glucose conditions were assayed by Western blot and ELISA. SUV39H1 was overexpressed in HK-2 cells; the regulation of SUV39H1 and H3K9me3 on NF-κB, IL-6, MCP-1, caspase 3, and apoptosis was measured. SUV39H1 was expressed more in diabetic human renal tubules. HK-2 cells with high glucose up-regulated IL-6 and MCP-1 in a dose- and time-dependent manner, and SUV39H1 expression was reduced with greater glucose and prolonged stimulation. Expression of H3K9me3 was synchronized with SUV39H1. Moreover, overexpression of SUV39H1 in high glucose environment was accompanied with increased H3K9me3 and decreased inflammation and apoptosis. SUV39H1 dysregulation may be involved in DN progression. Overexpression of SUV39H1 may reduce renal inflammation and apoptosis via epigenetic modulation, thus plays a protective role in DN.

Serum fibrinogen predicts diabetic ESRD in patients with type 2 diabetes mellitus

AIMS

Although increased serum fibrinogen level was often observed in patients with diabetic nephropathy (DN), its association with DN severity and progression remains unclear. The aim of this study was to investigate the relationship between the serum fibrinogen levels and clinicopathological features and renal prognosis in Chinese patients with type 2 diabetes mellitus (T2DM) and DN.

METHODS

A total of 174 patients with T2DM and biopsy-proven DN were enrolled. Patients were stratified by the quartiles of serum fibrinogen levels; Q1: <3.30 g/L; Q2: between 3.30 and 4.00 g/L; Q3: between 4.00 and 4.74 g/L; Q4:≥4.74 g/L. The renal outcomes were defined by reaching end stage renal disease (ESRD). The influence of serum fibrinogen levels on renal outcomes was evaluated using Cox regression analysis.

RESULTS

The factors associated with higher level of fibrinogen (Q3 and Q4) were diabetic retinopathy, low e-GFR, high proteinuria and severe glomerular and tubulointerstitial lesions. Importantly, in adjusted analysis, higher levels of fibrinogen were independently related with a greater risk of reaching ESRD with a hazard ratio (HR) of 1.64 per standard deviation (SD) of the natural log-transformed fibrinogen concentration (95%CI, 1.22-2.20; p = 0.001). In reference to the Q1, the risk of renal failure increased by quartiles of the serum fibrinogen level: the HRs were 7.12 for the Q2 (95%CI, 2.29-22.16; p = 0.001), 5.77 for Q3 (95%CI, 1.99-16.75; p = 0.001), and 8.81 for Q4 (95%CI, 2.79-27.80; p < 0.001).

CONCLUSIONS

These findings suggested that the elevated serum levels of fibrinogen were associated with diabetic ESRD in patients with T2DM.

The Role of TLR4 on PGC-1α-Mediated Oxidative Stress in Tubular Cell in Diabetic Kidney Disease

The role and precise mechanism of TLR4 in mitochondria-related oxidative damage and apoptosis of renal tubules in diabetic kidney disease (DKD) remain unclear. We examined the expression of TLR4 in renal biopsy tissues. Db/db diabetic mice and HK-2 cells cultured under high glucose (HG) were used as in vivo and vitro models. Real-time RT-PCR, Western blot, and immunohistochemistry were performed to examine the mRNA and protein levels of TLR4, NF-κΒ, PGC-1α, cytochrome C, and cleaved caspase-3. ATP level, activity of electron transport chain complex III, and antioxidant enzymes were investigated for mitochondrial function. Electron microscopy (EM) and MitoTracker Red CMXRos were used for mitochondrial morphology alteration. DHE staining and TUNEL assay were detected for ROS accumulation and apoptosis. PGC-1α plasmids were used for the overexpression of PGC-1α in HK-2. TAK242 and parthenolide were used as TLR4 and NF-κB blockers, respectively. Results showed that TLR4 was extensively expressed in the renal tubules of DKD patients and db/db diabetic mice, which was positively related to the tubular interstitial damage score and urinary β-NAG levels. In diabetic mice, inhibition of TLR4 could reverse the decreased expression of PGC-1α, increased expression of cytochrome C and cleaved caspase-3, mitochondrial dysfunction and deformation, increased accumulation of ROS, and activation of tubular cell apoptosis. In vitro, inhibition of TLR4 or NF-κB showed consistent results. PGC-1α overexpression could reverse the mitochondrial dysfunction, increased cleaved caspase-3, and apoptosis in HK-2 cells treated with HG. Data indicated that the TLR4/NF-κB signaling pathway might be the upstream pathway of PGC-1α and promote the tubular damage of DKD by modulating the mitochondria-related oxidative damage and apoptosis.

Reactive oxygen species promote tubular injury in diabetic nephropathy: The role of the mitochondrial ros-txnip-nlrp3 biological axis

NLRP3/IL-1β activation via thioredoxin (TRX)/thioredoxin-interacting protein (TXNIP) following mitochondria ROS (mtROS) overproduction plays a key role in inflammation. However, the involvement of this process in tubular damage in the kidneys of patients with diabetic nephropathy (DN) is unclear. Here, we demonstrated that mtROS overproduction is accompanied by decreases in TRX expression and TXNIP up-regulation. In addition, we discovered that mtROS overproduction is also associated with increases in NLRP3/IL-1β and TGF-β expression in the kidneys of patients with DN and db/db mice. We reversed these changes in db/db mice by administering a peritoneal injection of MitoQ, an antioxidant targeting mtROS. Similar results were observed in human tubular HK-2 cells subjected to high-glucose (HG) conditions and treated with MitoQ. Treating HK-2 cells with MitoQ suppressed the dissociation of TRX from TXNIP and subsequently blocked the interaction between TXNIP and NLRP3, leading to the inhibition of NLRP3 inflammasome activation and IL-1β maturation. The effects of MitoQ were enhanced by pretreatment with TXNIP siRNA and abolished by pretreatment with monosodium urate (MSU) and TRX siRNA in vitro. These results suggest that mitochondrial ROS-TXNIP/NLRP3/IL-1β axis activation is responsible for tubular oxidative injury, which can be ameliorated by MitoQ via the inhibition of mtROS overproduction.

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Reactive oxygen species promotes renal damage in diabetic nephropathy.

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Mitochondrial ROS- TXNIP-NLRP3 biological axis involved in tubular injury of DN.

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Inhibition of mitochondrial ROS by MitoQ ameliorated the renal tubular injury.

Probucol ameliorates renal injury in diabetic nephropathy by inhibiting the expression of the redox enzyme p66Shc

AIMS

Probucol is an anti-hyperlipidemic agent and a potent antioxidant drug that can delay progression of diabetic nephropathy (DN) and reverses renal oxidative stress in diabetic animal models; however, the mechanisms underlying these effects remain unclear. p66Shc is a newly recognized mediator of mitochondrial ROS production in renal cells under high-glucose (HG) ambience. We previously showed that p66Shc can serve as a biomarker for renal oxidative injury in DN patients and that p66Shc up-regulation is correlated with renal damage in vivo and in vitro. Here, we determined whether probucol ameliorates renal injury in DN by inhibiting p66Shc expression.

RESULTS

We found that the expression of SIRT1, Ac-H3 and p66Shc in kidneys of DN patients was altered. Also, probucol reduced the levels of serum creatinine, urine protein and LDL-c and attenuated renal oxidative injury and fibrosis in STZ induced diabetic mice. In addition, probucol reversed p-AMPK, SIRT1, Ac-H3 and p66Shc expression. Correlation analyses showed that p66Shc expression was correlated with p-AMPK and Sirt1 expression and severity of renal injury. In vitro pretreatment of HK-2 cells with p-AMPK and SIRT1 siRNA negated the beneficial effects of probucol. Furthermore, we noted that probucol activates p-AMPK and Sirt1 and inhibits p66shc mRNA transcription by facilitating the binding of Sirt1 to the p66Shc promoter and modulation of Ac-H3 expression in HK-2 cells under HG ambience.

INNOVATION AND CONCLUSION

Our results suggest for the first time that probucol ameliorates renal damage in DN by epigenetically suppressing p66Shc expression via the AMPK-SIRT1-AcH3 pathway.