Pathologic classification of diabetic nephropathy

Sixty Years of Confronting Diabetes and Kidney Disease

The good old days were not good, at least in terms of treating patients with type 2 diabetes. In the 1960s, the development of a radioimmunoassay for insulin permitted determination of the distinguishing features of type 1 and type 2 diabetes. The latter was treated with sulfonylureas and then phenformin, although the mechanisms of action at the time were unknown. The University Group Diabetes Program was a randomized controlled trial experienced by my medical generation, and the results were dramatic, both medically and legally. Next came the thiazolidinediones. All compounds were associated with weight gain and any end point benefits were uncertain. Nevertheless, basic science explained how glucose is sensed and even found a home for sulfonylureas in some patients. Next came the boom in renin-angiotensin-aldosterone system blockade, sacred ground for many, albeit the benefits were less than astounding. Other wonder drugs came and went. Over the decades, great strides were made in defining the pathology of diabetic renal disease, which is appropriate because the condition has become a primary cause of end-stage renal failure. Nonetheless, recent advances have turned around a depressing situation and are reasons for optimism. We now have compounds that actually could help patients with type 2 diabetes. One hundred years after insulin's introduction, it is high time.

Update on Diabetic Kidney Disease (DKD): Focus on Non-Albuminuric DKD and Cardiovascular Risk

The classic description of diabetic kidney disease (DKD) involves progressive stages of glomerular hyperfiltration, microalbuminuria, proteinuria, and a decline in the estimated glomerular filtration rate (eGFR), leading to dialysis. In recent years, this concept has been increasingly challenged as evidence suggests that DKD presents more heterogeneously. Large studies have revealed that eGFR decline may also occur independently from the development of albuminuria. This concept led to the identification of a new DKD phenotype: non-albuminuric DKD (eGFR < 60 mL/min/1.73 m², absence of albuminuria), whose pathogenesis is still unknown. However, various hypotheses have been formulated, the most likely of which is the acute kidney injury-to-chronic kidney disease (CKD) transition, with prevalent tubular, rather than glomerular, damage (typically described in albuminuric DKD). Moreover, it is still debated which phenotype is associated with a higher cardiovascular risk, due to contrasting results available in the literature. Finally, much evidence has accumulated on the various classes of drugs with beneficial effects on DKD; however, there is a lack of studies analyzing the different effects of drugs on the various phenotypes of DKD. For this reason, there are still no specific guidelines for therapy in one phenotype rather than the other, generically referring to diabetic patients with CKD.

ATF5 regulates tubulointerstitial injury in diabetic kidney disease via mitochondrial unfolded protein response

BACKGROUND

Mitochondrial quality control (MQC) plays a critical role in the progression of tubulointerstitial injury in diabetic kidney disease (DKD). The mitochondrial unfolded protein response (UPRmt), which is an important MQC process, is activated to maintain mitochondrial protein homeostasis in response to mitochondrial stress. Activating transcription factor 5 (ATF5) is critical in the mammalian UPRmt via mitochondria-nuclear translocation. However, the role of ATF5 and UPRmt in tubular injury under DKD conditions is unknown.

METHODS

ATF5 and UPRmt-related proteins including heat shock protein 60 (HSP60) and Lon peptidase 1 (LONP1), in DKD patients and db/db mice were examined by immunohistochemistry (IHC) and western blot analysis. Eight-week-old db/db mice were injected with ATF5-shRNA lentiviruses via the tail vein, and a negative lentivirus was used as a control. The mice were euthanized at 12 weeks, and dihydroethidium (DHE) and TdT-mediated dUTP nick end labeling (TUNEL) assays were performed to evaluate reactive oxygen species (ROS) production and apoptosis in kidney sections, respectively. In vitro, ATF5-siRNA, ATF5 overexpression plasmids or HSP60-siRNA were transfected into HK-2 cells to evaluate the effect of ATF5 and HSP60 on tubular injury under ambient hyperglycemic conditions. Mitochondrial superoxide (MitoSOX) staining was used to gauge mitochondrial oxidative stress levels, and the early stage of cell apoptosis was examined by Annexin V-FITC kits.

RESULTS

Increased ATF5, HSP60 and LONP1 expression was observed in the kidney tissue of DKD patients and db/db mice and was tightly correlated with tubular damage. The inhibition of HSP60 and LONP1, improvements in serum creatinine, tubulointerstitial fibrosis and apoptosis were observed in db/db mice treated with lentiviruses carrying ATF5 shRNA. In vitro, the expression of ATF5 was increased in HK-2 cells exposed to high glucose (HG) in a time-dependent manner, which was accompanied by the overexpression of HSP60, fibronectin (FN) and cleaved-caspase3 (C-CAS3). ATF5-siRNA transfection inhibited the expression of HSP60 and LONP1, which was accompanied by reduced oxidative stress and apoptosis in HK-2 cells exposed to sustained exogenous high glucose. ATF5 overexpression exacerbated these impairments. HSP60-siRNA transfection blocked the effect of ATF5 on HK-2 cells exposed to continuous HG treatment. Interestingly, ATF5 inhibition exacerbated mitochondrial ROS levels and apoptosis in HK-2 cells in the early period of HG intervention (6 h).

CONCLUSIONS

ATF5 could exert a protective effect in a very early stage but promoted tubulointerstitial injury by regulating HSP60 and the UPRmt pathway under DKD conditions, providing a potential target for the prevention of DKD progression.

Treatment effects of soluble guanylate cyclase modulation on diabetic kidney disease at single-cell resolution

Diabetic kidney disease (DKD) is the most common cause of renal failure. Therapeutics development is hampered by our incomplete understanding of animal models on a cellular level. We show that ZSF1 rats recapitulate human DKD on a phenotypic and transcriptomic level. Tensor decomposition prioritizes proximal tubule (PT) and stroma as phenotype-relevant cell types exhibiting a continuous lineage relationship. As DKD features endothelial dysfunction, oxidative stress, and nitric oxide depletion, soluble guanylate cyclase (sGC) is a promising DKD drug target. sGC expression is specifically enriched in PT and stroma. In ZSF1 rats, pharmacological sGC activation confers considerable benefits over stimulation and is mechanistically related to improved oxidative stress regulation, resulting in enhanced downstream cGMP effects. Finally, we define sGC gene co-expression modules, which allow stratification of human kidney samples by DKD prevalence and disease-relevant measures such as kidney function, proteinuria, and fibrosis, underscoring the relevance of the sGC pathway to patients.

Diabetes Mellitus and Diabetic Kidney Disease: The Future Is Already Here

Diabetes mellitus (DM) is a metabolic systemic disease with a high rate of morbidity and mortality [...].

Reorganization and Suppression of Store-Operated Calcium Entry in Podocytes of Type 2 Diabetic Rats

Type 2 diabetes mellitus (DM2) is a widespread metabolic disorder that results in podocyte damage and diabetic nephropathy. Previous studies demonstrated that TRPC6 channels play a pivotal role in podocyte function and their dysregulation is associated with development of different kidney diseases including nephropathy. Here, using single channel patch clamp technique, we demonstrated that non-selective cationic TRPC6 channels are sensitive to the Ca²⁺ store depletion in human podocyte cell line Ab8/13 and in freshly isolated rat glomerular podocytes. Ca²⁺ imaging indicated the involvement of ORAI and sodium-calcium exchanger in Ca²⁺ entry induced upon store depletion. In male rats fed a high-fat diet combined with a low-dose streptozotocin injection, which leads to DM2 development, we observed the reduction of a store-operated Ca²⁺ entry (SOCE) in rat glomerular podocytes. This was accompanied by a reorganization of store-operated Ca²⁺ influx such that TRPC6 channels lost their sensitivity to Ca²⁺ store depletion and ORAI-mediated Ca²⁺ entry was suppressed in TRPC6-independent manner. Altogether our data provide new insights into the mechanism of SOCE organization in podocytes in the norm and in pathology, which should be taken into account when developing pharmacological treatment of the early stages of diabetic nephropathy.

Vitamin D Ameliorates Podocyte Injury by Enhancing Autophagy Activity in Diabetic Kidney Disease

INTRODUCTION

Restoration of podocyte autophagy is considered as a feasible strategy for the treatment of diabetic kidney disease (DKD). This study aimed at investigating the protective effect and potential mechanism of vitamin D on podocyte injury of DKD.

METHODS

Type 2 diabetic db/db mice received intraperitoneal injections of vitamin D analog paricalcitol 400 ng/kg per day for 16 weeks. Immortalized mouse podocytes were cultured in high glucose (HG) medium with active vitamin D3 calcitriol or autophagy inhibitor 3-methyladenine. Renal function and urine albumin creatinine ratio were assessed at week 24. HE, PAS staining, and electron microscopy were used to evaluate renal histopathology and morphological changes. Immunohistochemistry, immunofluorescence, and Western blot were used to evaluate protein expression of nephrin and podocin in kidney tissue and podocytes. The expression of autophagy-related proteins (LC3, Beclin-1, Vps34) and apoptosis-related proteins (cleaved caspase-3, Bax) was determined by Western blotting. Podocyte apoptosis was further evaluated by using flow cytometer.

RESULTS

Albuminuria in a db/db mouse model was markedly attenuated after treatment with paricalcitol. This was accompanied by alleviation of mesangial matrix expansion and podocyte injury. Besides, the impaired autophagy in podocytes under diabetic conditions was also markedly enhanced after paricalcitol or calcitriol treatment, accompanied by restored decreased podocyte slit diaphragm proteins podocin and nephrin. Furthermore, the protective effect of calcitriol against HG-induced podocyte apoptosis could be abated by autophagy inhibitor 3-methyladenine.

CONCLUSION

Vitamin D ameliorates podocyte injury of DKD by enhancing podocyte autophagy activity, which may become a potential candidate autophagy activator for the therapeutic interventions for DKD.

Functional and morphological renal changes in a Göttingen Minipig model of obesity-related and diabetic nephropathy

Obesity-related glomerulopathy and diabetic nephropathy (DN) are serious complications to metabolic syndrome and diabetes. The purpose was to study effects of a fat, fructose and cholesterol-rich (FFC) diet with and without salt in order to induce hypertension on kidney function and morphology in Göttingen Minipigs with and without diabetes. Male Göttingen Minipigs were divided into 4 groups: SD (standard diet, n = 8), FFC (FFC diet, n = 16), FFC-DIA (FFC diet + diabetes, n = 14), FFC-DIA + S (FFC diet with extra salt + diabetes, n = 14). Blood and urine biomarkers, glomerular filtration rate (GFR), blood pressure (BP) and resistive index (RI) were evaluated after 6-7 months (T1) and 12-13 months (T2). Histology, electron microscopy and gene expression (excluding FFC-DIA + S) were evaluated at T2. All groups fed FFC-diet displayed obesity, increased GFR and RI, glomerulomegaly, mesangial expansion (ME) and glomerular basement membrane (GBM) thickening. Diabetes on top of FFC diet led to increased plasma glucose and urea and proteinuria and tended to exacerbate the glomerulomegaly, ME and GBM thickening. Four genes (CDKN1A, NPHS2, ACE, SLC2A1) were significantly deregulated in FFC and/or FFC-DIA compared to SD. No effects on BP were observed. Göttingen Minipigs fed FFC diet displayed some of the renal early changes seen in human obesity. Presence of diabetes on top of FFC diet exacerbated the findings and lead to changes resembling the early phases of human DN.

Dapagliflozin delays renal fibrosis in diabetic kidney disease by inhibiting YAP/TAZ activation

In diabetic kidney disease (DKD), the long-term hyperactivation of yes-associated protein (YAP)/transcriptional coactivator PDZ-binding motif (TAZ) in renal proximal tubule epithelial cells (RPTCs) plays an important role in progressive tubulointerstitial fibrosis. Sodium-glucose cotransporter 2 (SGLT2) is highly expressed in RPTCs, but its relationship with YAP/TAZ in tubulointerstitial fibrosis in DKD is still unknown. The purpose of this study was to clarify whether the SGLT2 inhibitor (SGLT2i) dapagliflozin could alleviate renal tubulointerstitial fibrosis in DKD by regulating YAP/TAZ. We examined 58 patients with DKD confirmed by renal biopsy and found that the expression and nuclear translocation of YAP/TAZ increased with the exacerbation of chronic kidney disease classification. In models of DKD, dapagliflozin showed similar effects to verteporfin, an inhibitor of YAP/TAZ, in reducing the activation of YAP/TAZ and downregulating the expression of their target genes, connective tissue growth factor (CTGF) and amphiregulin in vivo and in vitro. Silencing SGLT2 also confirmed this effect. Importantly, dapagliflozin showed a better effect than verteporfin in inhibiting inflammation, oxidative stress and fibrosis in the kidney in DKD rats. Taken together, this study proved for the first time that dapagliflozin delayed tubulointerstitial fibrosis at least partly by inhibiting YAP/TAZ activation, which further enriched the antifibrotic effect of SGLT2i.

Use of Histologic Parameters to Predict Glomerular Disease Progression: Findings From the China Kidney Biopsy Cohort Study

RATIONALE & OBJECTIVE

Challenges in achieving valid risk prediction and stratification impede treatment decisions and clinical research design for patients with glomerular diseases. This study evaluated whether chronic histologic changes, when complementing other clinical data, improved the prediction of disease outcomes across a diverse group of glomerular diseases.

STUDY DESIGN

Multicenter retrospective cohort study.

SETTING & PARTICIPANTS

4,982 patients with biopsy-proven glomerular disease who underwent native biopsy at 8 tertiary care hospitals across China in 2004-2020.

NEW PREDICTORS & ESTABLISHED PREDICTORS

Chronicity scores depicted as 4 categories of histological chronic change, as well as baseline clinical and demographic variables.

OUTCOME

Progression of glomerular disease defined as a composite of kidney failure or a ≥40% decrease in estimated glomerular filtration rate from the measurement at the time of biopsy.

ANALYTICAL APPROACH

Multivariable Cox proportional hazard models. The performance of predictive models was evaluated by C statistic, time-dependent area under the receiver operating characteristic curve (AUROC), net reclassification index, integrated discrimination index, and calibration plots.

RESULTS

The derivation and validation cohorts included 3,488 and 1,494 patients, respectively. During a median of 31 months of follow-up, a total of 444 (8.9%) patients had disease progression in the 2 cohorts. For prediction of the 2-year risk of disease progression, the AUROC of the model combining chronicity score and the Kidney Failure Risk Equation (KFRE) in the validation cohort was 0.76 (95% CI, 0.65-0.87); in comparison with the KFRE model (AUROC, 0.68 [95% CI, 0.56-0.79]), the combined model was significantly better (P = 0.04). The combined model also had a better fit, with a lower Akaike information criterion and a significant improvement in reclassification as assessed by the integrated discrimination improvements and net reclassification improvements. Similar improvements in predictive performance were observed in subgroup and sensitivity analyses.

LIMITATIONS

Selection bias, relatively short follow-up, lack of external validation.

CONCLUSIONS

Adding histologic chronicity scores to the KFRE model improved the prediction of kidney disease progression at the time of kidney biopsy in patients with glomerular diseases.

PLAIN-LANGUAGE SUMMARY

Risk prediction and stratification remain big challenges for treatment decisions and clinical research design for patients with glomerular diseases. The extent of chronic changes is an important component of kidney biopsy evaluations in glomerular disease. In this large multicenter cohort including 4,982 Chinese adults undergoing native kidney biopsy, we evaluated whether histologic chronicity scores, when added to clinical data, could improve the prediction of disease prognosis for a diverse set of glomerular diseases. We observed that adding histologic chronicity scores to the kidney failure risk equation improved the prediction of kidney disease progression at the time of kidney biopsy in patients with glomerular diseases.

Melatonin ameliorates serobiochemical alterations and restores the cardio-nephro diabetic vascular and cellular alterations in streptozotocin-induced diabetic rats

Melatonin possesses a wide range of pharmacological activities, including antidiabetic properties. Diabetes mellitus (DM) induces several physiopathological changes in body organs, which could be observed lately after systemic failure. In the current study, we aimed to investigate the serobiochemical changes and the histopathological picture in the diabetic heart and the kidney early before chronic complications and highlight the association between hyperglycemia, glomerular alterations, and cardiovascular changes. In addition, the role of melatonin in the treatment of cardio-nephro diabetic vascular and cellular adverse changes in streptozotocin-induced diabetic rats was also studied. A total of 40 mature Wistar albino rats were distributed into five groups; (1) control untreated rats, (2) diabetic mellitus untreated (DM) rats, in which DM was induced by the injection of streptozotocin (STZ), (3) control melatonin-treated (MLT), (4) melatonin-treated diabetic (DM + MLT) rats, in which melatonin was injected (10 mg/kg/day, i.p.) for 4 weeks, and (5) insulin-treated diabetic (DM + INS) rats. The serum biochemical analysis of diabetic STZ rats showed a significant (P &lt; 0.05) increase in the concentrations of blood glucose, total oxidative capacity (TOC), CK-MB, endothelin-1, myoglobin, H-FABP, ALT, AST, urea, and creatinine as compared to control rats. In contrast, there was a significant (P &lt; 0.05) decrease in serum concentration of insulin, total antioxidative capacity (TAC), total nitric oxide (TNO), and total protein level in DM rats vs. the control rats. Significant improvement in the serobiochemical parameters was noticed in both (DM + MLT) and (DM + INS) groups as compared with (DM) rats. The histological examination of the DM group revealed a disorder of myofibers, cardiomyocyte nuclei, and an increase in connective tissue deposits in between cardiac tissues. Severe congestion and dilation of blood capillaries between cardiac muscle fibers were also observed. The nephropathic changes in DM rats revealed various deteriorations in glomeruli and renal tubular cells of the same group. In addition, vascular alterations in the arcuate artery at the corticomedullary junction and interstitial congestion take place. Melatonin administration repaired all these histopathological alterations to near-control levels. The study concluded that melatonin could be an effective therapeutic molecule for restoring serobiochemical and tissue histopathological alterations during diabetes mellitus.

Suramin Affects the Renal VEGF-A/VEGFR Axis in Short-Term Streptozotocin-Induced Diabetes

Diabetic nephropathy (DN) accounts for approximately 50% of end-stage renal diseases. Vascular endothelial growth factor A (VEGF-A) is thought to be a critical mediator of vascular dysfunction in DN, but its role is unclear. The lack of pharmacological tools to modify renal concentrations further hinders the understanding of its role in DN. In this study, rats were evaluated after 3 weeks of streptozotocin-induced diabetes and two suramin treatments (10 mg/kg, ip). Vascular endothelial growth factor A expression was evaluated by western blot of glomeruli and immunofluorescence of the renal cortex. RT-PCR for receptors Vegfr1 mRNA and Vegfr2 mRNA quantitation was performed. The soluble adhesive molecules (sICAM-1, sVCAM-1) in blood were measured by ELISA and the vasoreactivity of interlobar arteries to acetylcholine was evaluated using wire myography. Suramin administration reduced the expression and intraglomerular localisation of VEGF-A. Increased VEGFR-2 expression in diabetes was reduced by suramin to non-diabetic levels. Diabetes reduced the sVCAM-1 concentrations. Suramin in diabetes restored acetylcholine relaxation properties to non-diabetic levels. In conclusion, suramin affects the renal VEGF-A/VEGF receptors axis and has a beneficial impact on endothelium-dependent relaxation of renal arteries. Thus, suramin may be used as a pharmacological agent to investigate the potential role of VEGF-A in the pathogenesis of renal vascular complications in short-term diabetes.

The Role of Histone Modifications in the Pathogenesis of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease. The pathogenesis of DKD is multifactorial, with several molecular pathways implicated. Recent data suggest that histone modification plays an important role in the development and progression of DKD. Histone modification appears to induce oxidative stress, inflammation and fibrosis in the diabetic kidney. In the present review, we summarize the current knowledge on the association between histone modification and DKD.

Measurement of Complement Activation via Plasma-Soluble C5b-9 Comparison with Terminal Complement Complex Staining in a Series of Kidney Biopsies

INTRODUCTION

With the emergence of therapeutic complement inhibitors, there is a need to identify patients with complement-driven inflammation. C5b-9 is the terminal product of the three complement pathways and therefore a marker of total complement activation. We present a pilot study which aims to assess whether plasma soluble C5b-9 (sC5b-9) correlates with terminal complement complex (TCC) staining in kidney tissue. The secondary aim was to assess the utility of plasma sC5b-9 as part of routine workup in kidney patients undergoing kidney biopsy.

METHODS

Thirty-seven patients undergoing kidney biopsy had plasma sC5b-9 and TCC staining on kidney tissue performed. Additional blood markers including creatinine, haemoglobin, CRP, factor H, factor I, and midkine levels were also taken. These parameters were correlated with the histological diagnoses. Patients were divided into a diseased group (n = 31) and a control group (n = 6) consisting of transplanted kidneys with minor or no changes. Of the biopsies in the control group, 50% were performed as per protocol, and the other 50% were performed due to clinical need.

RESULTS

There was no correlation found between plasma sC5b-9 and TCC kidney staining. Elevated sC5b-9 levels were found in a heterogeneous group of patients but were associated with higher CRP and lower haemoglobin levels. Overall, there was more TCC kidney staining in the diseased group compared with the control group, and a trend was observed of diabetic, primary membranous nephropathy, and amyloidosis patients having more intense glomerular and peritubular/interstitial staining.

CONCLUSION

Plasma sC5b-9 as a marker of total complement activation does not correlate with TCC kidney staining. This discordance suggests that plasma sC5b-9 and TCC staining are distinct markers of disease. TCC staining reflects chronicity and tissue deposition of complement over time. Conversely, plasma sC5b-9 concentrations change rapidly and reflect systemic complement activation. Complement activation was present in a heterogeneous group of kidney disease, indicating the underlying role of complement in many disorders.

Role of Klotho and AGE/RAGE-Wnt/β-Catenin Signalling Pathway on the Development of Cardiac and Renal Fibrosis in Diabetes

Fibrosis plays an important role in the pathogenesis of long-term diabetic complications and contributes to the development of cardiac and renal dysfunction. The aim of this experimental study, performed in a long-term rat model, which resembles type 1 diabetes mellitus, was to investigate the role of soluble Klotho (sKlotho), advanced glycation end products (AGEs)/receptor for AGEs (RAGE), fibrotic Wnt/β-catenin pathway, and pro-fibrotic pathways in kidney and heart. Diabetes was induced by streptozotocin. Glycaemia was maintained by insulin administration for 24 weeks. Serum and urine sKlotho, AGEs, soluble RAGE (sRAGE) and biochemical markers were studied. The levels of Klotho, RAGEs, ADAM10, markers of fibrosis (collagen deposition, fibronectin, TGF-β1, and Wnt/β-catenin pathway), hypertrophy of the kidney and/or heart were analysed. At the end of study, diabetic rats showed higher levels of urinary sKlotho, AGEs and sRAGE and lower serum sKlotho compared with controls without differences in the renal Klotho expression. A significant positive correlation was found between urinary sKlotho and AGEs and urinary albumin/creatinine ratio (uACR). Fibrosis and RAGE levels were significantly higher in the heart without differences in the kidney of diabetic rats compared to controls. The results also suggest the increase in sKlotho and sRAGE excretion may be due to polyuria in the diabetic rats.

[Electron microscopy in nephropathology]

Non-neoplastic kidney diseases represent a broad spectrum of diseases. Although their pathogenesis differs, the histological findings may be similar in terms of conventional morphology. A precise classification of these diseases is a prerequisite for correct therapy and prognostic assessment. In the diagnostic process, the magnification achieved by electron microscopy is essential and cannot be replaced by any other technique. The most frequent diagnostic questions addressed by ultrastructural studies represent (1) alterations of podocytes (e.g., minimal-change disease), (2) changes of the thickness and structure of the glomerular basement membrane (e.g., diabetic glomerulosclerosis or Alport disease), (3) the presence, characteristics and exact localisation of immune complexes (e.g., membranous glomerulonephritis or lupus nephritis), (4) alterations of endothelial cells and capillaries (e.g., thrombotic microangiopathy) and (5) diseases of the tubular cells (e.g., light-chain nephropathy or toxic effects). Therefore, ultrastructural investigations are-together with conventional microscopy and immunohistochemistry (or immunofluorescence)-an integral part of the so-called triple-diagnostics in routine nephropathology.

SIK2 protects against renal tubular injury and the progression of diabetic kidney disease

Despite optimal medical therapy, many patients with diabetic kidney disease (DKD) progress to end-stage renal disease. The identification of new biomarkers and drug targets for DKD is required for the development of more effective therapies. The apoptosis of renal tubular epithelial cells is a key feature of the pathogenicity associated with DKD. SIK2, a salt-inducible kinase, regulates important biological processes, such as energy metabolism, cell cycle progression and cellular apoptosis. In our current study, a notable decrease in the expression of SIK2 was detected in the renal tubules of DKD patients and murine models. Functional experiments demonstrated that deficiency or inactivity of SIK2 aggravates tubular injury and interstitial fibrosis in diabetic mice. Based on transcriptome sequencing, molecular mechanism exploration revealed that SIK2 overexpression reduces endoplasmic reticulum (ER) stress-mediated tubular epithelial apoptosis by inhibiting the histone acetyltransferase activity of p300 to activate HSF1/Hsp70. Furthermore, the specific restoration of SIK2 in tubules blunts tubular and interstitial impairments in diabetic and vancomycin-induced kidney disease mice. Together, these findings indicate that SIK2 protects against renal tubular injury and the progression of kidney disease, and make a compelling case for targeting SIK2 for therapy in DKD.

Sodium benzoate attenuates 2,8-dihydroxyadenine nephropathy by inhibiting monocyte/macrophage TNF-α expression

Sodium benzoate (SB), a known D-amino acid oxidase (DAO) enzyme inhibitor, has an anti-inflammatory effect, although its role in renal damage has not been explored. 2,8-dihydroxyadenine crystal induced chronic kidney disease, in which TNF-α is involved in the pathogenesis, was established by oral adenine administration in C57BL/6JJcl mice (AdCKD) with or without SB to investigate its renal protective effects. SB significantly attenuated AdCKD by decreasing serum creatinine and urea nitrogen levels, and kidney interstitial fibrosis and tubular atrophy scores. The survival of AdCKD mice improved 2.6-fold by SB administration. SB significantly decreased the number of infiltrating macrophages observed in the positive F4/80 immunohistochemistry area and reduced the expression of macrophage markers and inflammatory genes, including TNF-α, in the kidneys of AdCKD. Human THP-1 cells stimulated with either lipopolysaccharide or TNF-α showed increased expression of inflammatory genes, although this was significantly reduced by SB, confirming the anti-inflammatory effects of SB. SB exhibited renal protective effects in AdCKD in DAO enzyme deficient mice, suggesting that anti-inflammatory effect of SB was independent of DAO enzyme activity. Moreover, binding to motif DNA sequence, protein level, and mRNA level of NF-κB RelB were significantly inhibited by SB in AdCKD kidneys and lipopolysaccharide treated THP-1 cells, respectively. We report that anti-inflammatory property of SB is independent of DAO enzymatic activity and is associated with down regulated NF-κB RelB as well as its downstream inflammatory genes such as TNF-α in AdCKD.

The UDPase ENTPD5 regulates ER stress-associated renal injury by mediating protein N-glycosylation

Impaired protein N-glycosylation leads to the endoplasmic reticulum (ER) stress, which triggers adaptive survival or maladaptive apoptosis in renal tubules in diabetic kidney disease (DKD). Therapeutic strategies targeting ER stress are promising for the treatment of DKD. Here, we report a previously unappreciated role played by ENTPD5 in alleviating renal injury by mediating ER stress. We found that ENTPD5 was highly expressed in normal renal tubules; however, ENTPD5 was dynamically expressed in the kidney and closely related to pathological DKD progression in both human patients and mouse models. Overexpression of ENTPD5 relieved ER stress in renal tubular cells, leading to compensatory cell proliferation that resulted in hypertrophy, while ENTPD5 knockdown aggravated ER stress to induce cell apoptosis, leading to renal tubular atrophy and interstitial fibrosis. Mechanistically, ENTPD5-regulated N-glycosylation of proteins in the ER to promote cell proliferation in the early stage of DKD, and continuous hyperglycemia activated the hexosamine biosynthesis pathway (HBP) to increase the level of UDP-GlcNAc, which driving a feedback mechanism that inhibited transcription factor SP1 activity to downregulate ENTPD5 expression in the late stage of DKD. This study was the first to demonstrate that ENTPD5 regulated renal tubule cell numbers through adaptive proliferation or apoptosis in the kidney by modulating the protein N-glycosylation rate in the ER, suggesting that ENTPD5 drives cell fate in response to metabolic stress and is a potential therapeutic target for renal diseases.

Spatially Aware Transformer Networks for Contextual Prediction of Diabetic Nephropathy Progression from Whole Slide Images

Diabetic nephropathy (DN) in the context of type 2 diabetes is the leading cause of end-stage renal disease (ESRD) in the United States. DN is graded based on glomerular morphology and has a spatially heterogeneous presentation in kidney biopsies that complicates pathologists' predictions of disease progression. Artificial intelligence and deep learning methods for pathology have shown promise for quantitative pathological evaluation and clinical trajectory estimation; but, they often fail to capture large-scale spatial anatomy and relationships found in whole slide images (WSIs). In this study, we present a transformer-based, multi-stage ESRD prediction framework built upon nonlinear dimensionality reduction, relative Euclidean pixel distance embeddings between every pair of observable glomeruli, and a corresponding spatial self-attention mechanism for a robust contextual representation. We developed a deep transformer network for encoding WSI and predicting future ESRD using a dataset of 56 kidney biopsy WSIs from DN patients at Seoul National University Hospital. Using a leave-one-out cross-validation scheme, our modified transformer framework outperformed RNNs, XGBoost, and logistic regression baseline models, and resulted in an area under the receiver operating characteristic curve (AUC) of 0.97 (95% CI: 0.90-1.00) for predicting two-year ESRD, compared with an AUC of 0.86 (95% CI: 0.66-0.99) without our relative distance embedding, and an AUC of 0.76 (95% CI: 0.59-0.92) without a denoising autoencoder module. While the variability and generalizability induced by smaller sample sizes are challenging, our distance-based embedding approach and overfitting mitigation techniques yielded results that sugest opportunities for future spatially aware WSI research using limited pathology datasets.

Non-Diabetic Kidney Disease in Type 2 Diabetes Mellitus: A Changing Spectrum with Therapeutic Ascendancy

BACKGROUND AND OBJECTIVES

Owing to changing epidemiology and therapeutic practices, a change in the spectrum of renal involvement in Type-2 diabetes mellitus (T2DM) has also been noted. The treatment of non-diabetic kidney disease (NDKD) differs from diabetic kidney disease (DKD) and the reversibility of NDKD in many cases to normal, prompts biopsy for rapid and accurate diagnosis. Data are scarce on kidney biopsy findings in T2DM.

STUDY DESIGN & SETTING

In this observational study, we prospectively collected the data of kidney biopsies of patients aged ≥ 18 years with T2DM admitted between 1 August 2005 and 31 July 2022. The clinical, demographic and histopathological data were evaluated. The spectrum of kidney involvement in the form of DKD and/or NDKD was studied. The impact of these findings with the use of drugs retarding disease progression was also analyzed.

RESULTS

A total of 5485 biopsies were performed during the study period and of these 538 patients had T2DM. The mean age of the study population was 56.9 ± 11.5 years and 81% were males. The mean duration of DM was 6.4 ± 6.1 years. Diabetic retinopathy (DR) was noted in 29.7%. The most common indication for biopsy was an acute rise in creatinine (147, 27.3%). Amongst the 538 diabetic patients who underwent biopsy, histological features only of DKD were noted in 166 patients (33%), NDKD alone in 262 (49%) and NDKD with DKD lesions in 110 (20%). On multivariate analysis, duration of DM less than 5 years, absence of CAD, absence of DR, oliguria at presentation, an acute rise in creatinine and low C3 were associated with NDKD.

CONCLUSIONS

The prevalence of NDKD among diabetics and ATIN in particular might be on an increasing trend in the current era of changing T2DM epidemiological patterns. The use of anti-pro-teinuric agents was associated with lesser degrees of histopathological chronicity in T2DM.

The Mechanism of Hyperglycemia-Induced Renal Cell Injury in Diabetic Nephropathy Disease: An Update

Diabetic Nephropathy (DN) is a serious complication of type I and II diabetes. It develops from the initial microproteinuria to end-stage renal failure. The main initiator for DN is chronic hyperglycemia. Hyperglycemia (HG) can stimulate the resident and non-resident renal cells to produce humoral mediators and cytokines that can lead to functional and phenotypic changes in renal cells and tissues, interference with cell growth, interacting proteins, advanced glycation end products (AGEs), etc., ultimately resulting in glomerular and tubular damage and the onset of kidney disease. Therefore, poor blood glucose control is a particularly important risk factor for the development of DN. In this paper, the types and mechanisms of DN cell damage are classified and summarized by reviewing the related literature concerning the effect of hyperglycemia on the development of DN. At the cellular level, we summarize the mechanisms and effects of renal damage by hyperglycemia. This is expected to provide therapeutic ideas and inspiration for further studies on the treatment of patients with DN.

Molecular pathways that drive diabetic kidney disease

Kidney disease is a major driver of mortality among patients with diabetes and diabetic kidney disease (DKD) is responsible for close to half of all chronic kidney disease cases. DKD usually develops in a genetically susceptible individual as a result of poor metabolic (glycemic) control. Molecular and genetic studies indicate the key role of podocytes and endothelial cells in driving albuminuria and early kidney disease in diabetes. Proximal tubule changes show a strong association with the glomerular filtration rate. Hyperglycemia represents a key cellular stress in the kidney by altering cellular metabolism in endothelial cells and podocytes and by imposing an excess workload requiring energy and oxygen for proximal tubule cells. Changes in metabolism induce early adaptive cellular hypertrophy and reorganization of the actin cytoskeleton. Later, mitochondrial defects contribute to increased oxidative stress and activation of inflammatory pathways, causing progressive kidney function decline and fibrosis. Blockade of the renin-angiotensin system or the sodium-glucose cotransporter is associated with cellular protection and slowing kidney function decline. Newly identified molecular pathways could provide the basis for the development of much-needed novel therapeutics.

Ginsenoside Rg1 attenuates glomerular fibrosis by inhibiting CD36/TRPC6/NFAT2 signaling in type 2 diabetes mellitus mice

ETHNOPHARMACOLOGICAL RELEVANCE

Ginsenoside Rg1 (Rg1) is one of the main active components in Panax ginseng C. A. Meyer (ginseng), which has been widely used to delay senescence or improve health conditions for more than 2000 years. Increasing studies have revealed that Rg1 could regulate cell proliferation and differentiation, as well as anti-inflammatory and anti-apoptotic effects, and might have protective effects on many chronic kidney diseases.

AIM OF THE STUDY

Diabetic nephropathy (DN) is one of the most dangerous microvascular complications of diabetes and is the leading cause of end-stage renal disease worldwide. However, the role and mechanism of Rg1 against high-glucose and high-fat-induced glomerular fibrosis in DN are not clear. This study aimed to investigate the protective effect of Rg1 on DN and its possible mechanism.

MATERIALS AND METHODS

The type 2 diabetes mellitus (T2DM) mice models were established with a high-fat diet (HFD) combined with an intraperitoneal injection of streptozotocin (STZ). Urine protein and serum biochemical indexes were detected by corresponding kits. The kidney was stained with H&E, PAS, and Masson to observe the pathological morphology, glycogen deposition, and fibrosis. The expression of CD36 and p-PLC in the kidney cortex was detected by IHC. The expressions of FN and COL4 were detected by IF. Western blot and PCR were performed to examine protein and mRNA expressions of kidney fibrosis and TRPC6/NFAT2-related pathways in DN mice. Calcium imaging was used to examine the effect of Rg1 on [Ca²⁺]_i in PA + HG-induced human mesangial cells (HMCs). Visualization of the interaction between Rg1 and CD36 was detected by molecular docking.

RESULTS

Rg1 treatment for 8 weeks could prominently decrease urinary protein, serum creatinine, and urea nitrogen and downgrade blood lipid levels and renal lipid accumulation in T2DM mice. The pathological results indicated that Rg1 treatment attenuated renal pathological injury and glomerular fibrosis. The further results demonstrated that Rg1 treatment remarkably decreased the expressions of CD36, TRPC6, p-PLC, CN, NFAT2, TGF-β, p-Smad2/3, COL4, and FN in renal tissues from T2DM mice. Calcium imaging results found that Rg1 downgraded the base levels of [Ca²⁺]_i and ΔRatioF340/F380 after BAPTA and CaCl₂ treatment. Molecular docking results showed that Rg1 could interact with CD36 with a good affinity.

CONCLUSION

These results revealed that Rg1 could ameliorate renal lipid accumulation, pathological damage, and glomerular fibrosis in T2DM mice. The mechanism may be involved in reducing the overexpression of CD36 and inhibiting the TRPC6/NFAT2 signaling pathway in renal tissues of T2DM mice.

Network pharmacology analysis combined with experimental validation to explore the therapeutic mechanism of Schisandra Chinensis Mixture on diabetic nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic nephropathy (DN) is one of the most common and serious microvascular complications of Diabetes mellitus (DM). The inflammatory response plays a critical role in DN. Schisandra Chinensis Mixture (SM) has shown promising clinical efficacy in the treatment of DN while the pharmacological mechanisms are still unclear.

AIM OF THE STUDY

In this study, a network pharmacology approach and bioinformatic analysis were adopted to predict the pharmacological mechanisms of SM in DN therapy. Based on the predicted results, molecular docking and in vivo experiments were used for verification.

MATERIALS AND METHODS

In this study, the candidate bioactive ingredients of SM were obtained via Traditional Chinese Medicine Systems Pharmacology Database (TCMSP) and supplementing according to the literature. SM putative targets and the verified targets were acquired from TCMSP and SiwssTartgetPrediction Database. DN-related target genes were collected from GeneCards, OMIM, DisGeNET databases, and microarray data analysis. Biological function and pathway analysis were performed to further explore the pharmacological mechanisms of SM in DN therapy. The protein-protein interaction (PPI) network was established to screen the hub gene. The Receiver Operating Characteristic (ROC) analysis and the molecular docking simulations were performed to validate the potential target-drug interactions. The fingerprint spectrum of multi-components of the SM was characterized by UPLC-MS/MS. The signaling pathways associated with inflammation and hub genes were partially validated in SD rats.

RESULTS

A total of 36 bioactive ingredients were contained, and 666 component-related targets were screened from SM, of which 50 intersected with DN targets and were considered potential therapeutic targets. GO analyses revealed that the 50 intersection targets were mainly enriched in the inflammatory response, positive regulation of angiogenesis, and positive regulation of phosphatidylinositol 3-kinase(PI3K) signaling. KEGG analyses indicated that the PI3K-Akt signaling pathway was considered as the most important pathway for SM antagonism to the occurrence and development of DN, with the highest target count enrichment. PPI network results showed that the top 15 protein targets in degree value, VEGFA, JAK2, CSF1R, NOS3, CCR2, CCR5, TLR7, FYN, BTK, LCK, PLAT, NOS2, TEK, MMP1 and MCL1, were identified as hub genes. The results of ROC analysis showed that VEGFA and NOS3 were valuable in the diagnosis of DN. The molecular docking confirmed that the core bioactive ingredients had well-binding affinity for VEGFA and NOS3. The in vivo experiments confirmed that SM significantly inhibited the over-release of inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor receptor (TNF)-α in DN rats, while regulating the PI3K-AKT and VEGFA-NOS3 signaling pathways.

CONCLUSION

This study revealed the multi-component, multi-target and multi-pathway characteristics of SM therapeutic DN. SM inhibited the inflammatory response and improved renal pathological damage in DN rats, which was related to the regulation of the PI3K-Akt and VEGFA-NOS3 signaling pathways.

Association of triglycerides to high-density lipoprotein cholesterol ratio with incident cardiovascular disease but not end-stage kidney disease among patients with biopsy-proven diabetic nephropathy

Increased triglycerides (TG) and decreased high-density lipoprotein cholesterol (HDL-C) are dyslipidemias characteristic of diabetes. Here, we aimed to examine associations of TG/HDL-C ratio with cardiovascular disease (CVD) and kidney dysfunction among patients with diabetic nephropathy. This retrospective observational study consists of patients with biopsy-proven diabetic nephropathy at Nara Medical University Hospital. Exposure of interest was TG/HDL-C ratio measured at kidney biopsy. Outcome variables were kidney histological findings, incident CVD and end-stage kidney disease (ESKD). Multivariable logistic regression models and Cox proportional hazard models were used to examined these associations. A total of 353 subjects were divided into quartiles based on TG/HDL-C ratio: Quartile 1 (reference), <1.96; Quartile 2, 1.96-3.10; Quartile 3, 3.11-4.55; and Quartile 4, ≥4.56. TG/HDL-C ratio was not a predictor of any histological findings in fully adjusted models. During median follow-up periods of 6.2 and 7.3 years, 152 and 90 subjects developed CVD and ESKD, respectively. Higher TG/HDL-C ratio was independently associated with higher incidences of CVD even after adjustments for potential confounders (hazard ratio [95% confidence interval] for Quartile 3 vs. reference; 1.73 [1.08-2.79] and Quartile 4 vs. reference; 1.86 [1.10-3.17]). Although there was a weak association between TG/HDL-C ratio and ESKD in the univariable model, the association was not significant in fully adjusted models. In conclusion, among patients with biopsy-proven diabetic nephropathy, higher TG/HDL-C ratio was independently associated with higher incidences of CVD but not with kidney outcomes, suggesting different impact of TG/HDL-C ratio on cardiorenal outcomes.

Diabetic Kidney Disease in Post-Transplant Diabetes Mellitus: Causes, Treatment and Outcomes

Kidney transplant recipients are a unique subgroup of chronic kidney disease patients due to their single functioning kidney, immunosuppressive agent usage, and long-term complications related to transplantation. Post-transplant diabetes mellitus (PTDM) has a significant adverse effect on renal outcomes in particular. As transplantations enable people to live longer, cardiovascular morbidity and mortality become more prevalent, and PTDM is a key risk factor for these complications. Although PTDM results from similar risk factors to those of type 2 diabetes, the conditions differ in their pathophysiology and clinical features. Transplantation itself is a risk factor for diabetes due to chronic exposure to immunosuppressive agents. Considering current evidence, this article describes the risk factors, pathogenesis, diagnostic criteria, prevention strategies, and management of PTDM. The therapeutic options are discussed regarding their safety and potential drug-drug interactions with immunosuppressive agents.

Metabolic-associated fatty liver disease increases the risk of end-stage renal disease in patients with biopsy-confirmed diabetic nephropathy: a propensity-matched cohort study

AIMS

To investigate the relationship between metabolic-associated fatty liver disease (MAFLD) and end-stage renal disease (ESRD) in patients with biopsy-confirmed diabetic nephropathy (DN).

METHODS

A total of 316 participants with biopsy-confirmed DN between January 2008 and December 2019 were retrospectively assessed. Kaplan-Meier curve and Cox proportional hazard models were used to compare the risk of incident ESRD in 50 patients with MAFLD and 50 patients without MAFLD, after using propensity score matching (PSM) to address the imbalances of sex, age, baseline-estimated glomerular filtration rate, serum albumin, 24-h urine protein, hemoglobin and systolic blood pressure.

RESULTS

During the median follow-up period of 3 years, there were 19 ESRD outcome events (19%) in PSM cohort. Kaplan-Meier curve analysis suggested that renal survival significantly deteriorated in patients with MAFLD versus those without MAFLD (p = 0.021). Additionally, the hazard ratios (95% confidence interval) of MAFLD were 3.12 (1.09-8.95, p = 0.035), 3.36 (1.09-10.43, p = 0.036), 3.66 (1.22-10.98, p = 0.021), 4.25 (1.34-13.45, p = 0.014), 3.11 (1.08-8.96, p = 0.035) and 5.84 (1.94-18.5, p = 0.003) after adjustment for six models, including demographic, clinical and pathological characteristics as well as medication use at the time of renal biopsy, respectively. Besides, patients with higher liver fibrosis score had a greater possibility of ESRD, comparing to those with lower liver fibrosis score (p = 0.002).

CONCLUSIONS

MAFLD increases the risk of incident ESRD in patients with biopsy-proven DN. Further research is needed to determine whether treatment targeting MAFLD improves the prognosis of DN.

A dynamic nomogram for predicting survival among diabetic patients on maintenance hemodialysis

INTRODUCTION

Among maintenance hemodialysis (MHD) patients, ones with diabetes mellitus (DM) are known to have the worst outcome.

METHODS

A total of 263 MHD patients were included, a dynamic nomogram was established based on multivariable Cox regression analysis.

RESULTS

The median overall survival (OS) time was 46 months. The 1-, 3-, and 5-year OS rates were 90.9%, 70.5% and 53.9%, respectively. The multivariable Cox regression analysis indicated that DM duration, cardiovascular complication, baseline values before starting MHD for estimated glomerular filtration rate and serum phosphate were independent risk factors. The C-index of the dynamic nomogram was 0.745 and the calibration curves showed optimal agreement between the model prediction and actual observation for predicting survival probabilities.

CONCLUSIONS

Our study was the first to establish dynamic nomogram among diabetic MHD patients, the fast and convenient online tool can be used for individual risk estimation at the point of prognosis prediction.

Fyn deficiency inhibits oxidative stress by decreasing c-Cbl-mediated ubiquitination of Sirt1 to attenuate diabetic renal fibrosis

OBJECTIVE

Oxidative stress (OS) is the main cause leading to diabetic renal fibrosis. Recently, Fyn was paid much attention on OS and emerged as a pivotal player in acute kidney injury, while whether Fyn regulates oxidative stress in chronic diabetes nephropathy (DN) has not been clarified yet. The purpose of this study was to identify the role of Fyn in DN and elucidated its regulatory mechanism.

METHODS

The db/db mice and littermate control C57BKS/J mice were injected by tail vein with Fyn interfering adenovirus or Fyn overexpressing adenovirus to investigate the role of Fyn in vivo. Primary glomerular mesangial cells (GMCs) were used for in vitro studies.

RESULTS

Fyn was up-regulated in high glucose (HG)-induced GMCs and kidneys of diabetic mice. Additionally, Fyn knockdown reduced the level of OS in HG-induced GMCs and kidneys of diabetic mice, thereby ameliorating diabetic renal fibrosis. While overexpression of Fyn significantly increased the level of OS in GMCs and kidney tissues, resulting in renal damage. Moreover, Fyn deficiency exerted antioxidant effects by activating the Sirt1/Foxo3a pathway. Mechanistically, Fyn facilitated the combination of c-Cbl and Sirt1 by phosphorylating c-Cbl at Tyr⁷³¹, which triggered K48-linked polyubiquitination of Sirt1 at Lys³⁷⁷ and Lys⁵¹³ by c-Cbl and promoted Sirt1 degradation, impairing the antioxidant effects of Foxo3a.

CONCLUSIONS

Fyn deficiency promoted Foxo3a nuclear transcription via reducing the ubiquitination of Sirt1 by c-Cbl, thereby alleviating renal oxidative damage in diabetic mice. These results identified Fyn as a potential therapeutic target against DN.

The Role of Macula Densa Nitric Oxide Synthase 1 Beta Splice Variant in Modulating Tubuloglomerular Feedback

Abnormalities in renal electrolyte and water excretion may result in inappropriate salt and water retention, which facilitates the development and maintenance of hypertension, as well as acid-base and electrolyte disorders. A key mechanism by which the kidney regulates renal hemodynamics and electrolyte excretion is via tubuloglomerular feedback (TGF), an intrarenal negative feedback between tubules and arterioles. TGF is initiated by an increase of NaCl delivery at the macula densa cells. The increased NaCl activates luminal Na-K-2Cl cotransporter (NKCC2) of the macula densa cells, which leads to activation of several intracellular processes followed by the production of paracrine signals that ultimately result in a constriction of the afferent arteriole and a tonic inhibition of single nephron glomerular filtration rate. Neuronal nitric oxide (NOS1) is highly expressed in the macula densa. NOS1β is the major splice variant and accounts for most of NO generation by the macula densa, which inhibits TGF response. Macula densa NOS1β-mediated modulation of TGF responses plays an essential role in control of sodium excretion, volume and electrolyte hemostasis, and blood pressure. In this article, we describe the mechanisms that regulate macula densa-derived NO and their effect on TGF response in physiologic and pathologic conditions. © 2023 American Physiological Society. Compr Physiol 13:4215-4229, 2023.

Urinary Extracellular Vesicles in Chronic Kidney Disease: From Bench to Bedside?

Extracellular vesicles are a diverse group of particles that include exosomes, microvesicles, and apoptotic bodies and are defined by size, composition, site of origin, and density. They incorporate various bioactive molecules from their cell of origin during formation, such as soluble proteins, membrane receptors, nucleic acids (mRNAs and miRNAs), and lipids, which can then be transferred to target cells. Extracellular vesicles/exosomes have been extensively studied as a critical factor in pathophysiological processes of human diseases. Urinary extracellular vesicles could be a promising liquid biopsy for determining the pattern and/or severity of kidney histologic injury. The signature of urinary extracellular vesicles may pave the way for noninvasive methods to supplement existing testing methods for diagnosing kidney diseases. We discuss the potential role of urinary extracellular vesicles in various chronic kidney diseases in this review, highlighting open questions and discussing the potential for future research.

Thrombomodulin activation driven by LXR agonist attenuates renal injury in diabetic nephropathy

Objective

Inflammation and thrombosis are recognized as interrelated biological processes. Both thrombomodulin (TM) and factor XIII-A (FXIII-A) are involved in inflammation and coagulation process. However, their role in the pathogenesis of diabetic nephropathy (DN) remains unclear. In vitro study, the liver X receptor (LXR) agonist T0901317 can up-regulate the expression of TM in glomerular endothelial cells. Now we evaluated the interaction between TM activation and FXIII-A and their effects against renal injury.

Methods

We first evaluated the serum levels of FXIII-A and TM and the expression of TM, LXR-α and FXIII-A in renal tissues of patients with biopsy-proven DN. We then analyzed the expression of TM, LXR-α and FXIII-A in renal tissues of db/db DN mice after upregulating TM expression via T0901317 or downregulating its expression via transfection of TM shRNA-loaded adenovirus. We also investigated the serum levels of Tumor necrosis factor (TNF)-α, Interleukin (IL)-6, creatinine, and urinary microalbumin level in db/db mice.

Results

Our study showed that elevations in serum levels of FXIII-A positively correlated to the serum levels of TM and were also associated with end-stage kidney disease in patients with DN. The number of TM⁺ cells in the renal tissues of patients with DN negatively correlated with the number of FXIII-A⁺ cells and positively correlated with the number of LXR-α⁺ cells and estimated glomerular filtration rate (eGFR), whereas the number of FXIII-A⁺ cells negatively correlated with the eGFR.

Conclusion

Thrombomodulin activation with T0901317 downregulated FXIII-A expression in the kidney tissue and alleviated renal injury in db/db mice.

Recent advances in molecular mechanisms of acute kidney injury in patients with diabetes mellitus

Several insults can lead to acute kidney injury (AKI) in native kidney and transplant patients, with diabetes critically contributing as pivotal risk factor. High glucose per se can disrupt several signaling pathways within the kidney that, if not restored, can favor the instauration of mechanisms of maladaptive repair, altering kidney homeostasis and proper function. Diabetic kidneys frequently show reduced oxygenation, vascular damage and enhanced inflammatory response, features that increase the kidney vulnerability to hypoxia. Importantly, epidemiologic data shows that previous episodes of AKI increase susceptibility to diabetic kidney disease (DKD), and that patients with DKD and history of AKI have a generally worse prognosis compared to DKD patients without AKI; it is therefore crucial to monitor diabetic patients for AKI. In the present review, we will describe the causes that contribute to increased susceptibility to AKI in diabetes, with focus on the molecular mechanisms that occur during hyperglycemia and how these mechanisms expose the different types of resident renal cells to be more vulnerable to maladaptive repair during AKI (contrast- and drug-induced AKI). Finally, we will review the list of the existing candidate biomarkers of diagnosis and prognosis of AKI in patients with diabetes.

Protein restriction for diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) continues to be the leading cause of kidney failure across the world. For decades dietary protein restriction has been proposed for patients with DKD with the aim to retard the progression of chronic kidney disease (CKD) towards kidney failure. However, the relative benefits and harms of dietary protein restriction for slowing the progression of DKD have not been addressed.

OBJECTIVES

To determine the efficacy and safety of low protein diets (LPD) (0.6 to 0.8 g/kg/day) in preventing the progression of CKD towards kidney failure and in reducing the incidence of kidney failure and death (any cause) in adult patients with DKD. Moreover, the effect of LPD on adverse events (e.g. malnutrition, hyperglycaemic events, or health-related quality of life (HRQoL)) and compliance were also evaluated.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 17 November 2022 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs in which adults with DKD not on dialysis were randomised to receive either a LPD (0.6 to 0.8 g/kg/day) or a usual or unrestricted protein diet (UPD) (≥ 1.0 g/kg/day) for at least 12 months.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies and extracted data. Summary estimates of effect were obtained using a random-effects model. Results were summarised as risk ratios (RR) with 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised MD (SMD) with 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We identified eight studies involving 486 participants with DKD. The prescribed protein intake in the intervention groups ranged from 0.6 to 0.8 g/kg/day. The prescribed protein intake in the control groups was ≥ 1.0 g/kg/day, or a calculated protein intake ≥ 1.0 g/kg/day if data on prescribed protein intake were not provided. The mean duration of the interventions was two years (ranging from one to five years). Risks of bias in most of the included studies were high or unclear, most notably for allocation concealment, performance and detection bias. All studies were considered to be at high risk for performance bias due to the nature of the interventions. Most studies were not designed to examine death or kidney failure. In low certainty evidence, a LPD may have little or no effect on death (5 studies, 358 participants: RR 0.38, 95% CI 0.10 to 1.44; I² = 0%), and the number of participants who reached kidney failure (4 studies, 287 participants: RR 1.16, 95% CI 0.38 to 3.59; I² = 0%). Compared to a usual or unrestricted protein intake, it remains uncertain whether a LPD slows the decline of glomerular filtration rate over time (7 studies, 367 participants: MD -0.73 mL/min/1.73 m²/year, 95% CI -2.3 to 0.83; I² = 53%; very low certainty evidence). It is also uncertain whether the restriction of dietary protein intake impacts on the annual decline in creatinine clearance (3 studies, 203 participants: MD -2.39 mL/min/year, 95% CI -5.87 to 1.08; I² = 53%). There was only one study reporting 24-hour urinary protein excretion. In very low certainty evidence, a LPD had uncertain effects on the annual change in proteinuria (1 study, 80 participants: MD 0.90 g/24 hours, 95% CI 0.49 to 1.31). There was no evidence of malnutrition in seven studies, while one study noted this condition in the LPD group. Participant compliance with a LPD was unsatisfactory in nearly half of the studies. One study reported LPD had no effect on HRQoL. No studies reported hyperglycaemic events.

AUTHORS' CONCLUSIONS

Dietary protein restriction has uncertain effects on changes in kidney function over time. However, it may make little difference to the risk of death and kidney failure. Questions remain about protein intake levels and compliance with protein-restricted diets. There are limited data on HRQoL and adverse effects such as nutritional measures and hyperglycaemic events. Large-scale pragmatic RCTs with sufficient follow-up are required for different stages of CKD.

CureGN-Diabetes Study: Rationale, Design, and Methods of a Prospective Observational Study of Glomerular Disease Patients with Diabetes

Glomerular diseases (GDs) represent the third leading cause of end-stage kidney disease (ESKD) in the US Diabetes was excluded from the CureGN Study, an NIH/NIDDK-sponsored observational cohort study of four leading primary GDs: IgA nephropathy (IgAN), membranous nephropathy (MN), focal segmental glomerulosclerosis (FSGS), and minimal change disease (MCD). CureGN-Diabetes, an ancillary study to CureGN, seeks to understand how diabetes influences the diagnosis, treatment, and outcomes of GD. It is a multicenter, prospective cohort study, targeting an enrollment of 300 adults with prevalent type 1 or type 2 diabetes and MCD, FSGS, MN, or IgAN, with first kidney biopsy obtained within 5 years of enrollment in 80% (20% allowed if biopsy after 2010). CureGN and Transformative Research in DiabEtic NephropaThy (TRIDENT) provide comparator cohorts. Retrospective and prospective clinical data and patient-reported outcomes are obtained. Blood and urine specimens are collected at study visits annually. Kidney biopsy reports and digital images are obtained, and standardized pathologic evaluations performed. Light microscopy images are uploaded to the NIH pathology repository. Outcomes include relapse and remission rates, changes in proteinuria and estimated glomerular filtration rate, infections, cardiovascular events, malignancy, ESKD, and death. Multiple analytical approaches will be used leveraging the baseline and longitudinal data to compare disease presentation and progression across subgroups of interest. With 300 patients and an average of 3 years of follow-up, the study has 80% power to detect a HR of 1.4-1.8 for time to complete remission of proteinuria, a rate ratio for hospitalizations of 1.18-1.56 and difference in eGFR slope of 6.0-8.6 mL/min/year between two groups of 300 participants each. CureGN-Diabetes will enhance our understanding of diabetes as a modifying factor of the pathology and outcomes of GDs and support studies to identify disease mechanisms and improve patient outcomes in this understudied patient population.

Histological Manifestations of Diabetic Kidney Disease and its Relationship with Insulin Resistance

Histological manifestations of diabetic kidney disease (DKD) include mesangiolysis, mesangial matrix expansion, mesangial cell proliferation, thickening of the glomerular basement membrane, podocyte loss, foot process effacement, and hyalinosis of the glomerular arterioles, interstitial fibrosis, and tubular atrophy. Glomerulomegaly is a typical finding. Histological features of DKD may occur in the absence of clinical manifestations, having been documented in patients with normal urinary albumin excretion and normal glomerular filtration rate. Furthermore, the histological picture progresses over time, while clinical data may remain normal. Conversely, histological lesions of DKD improve with metabolic normalization following effective pancreas transplantation. Insulin resistance has been associated with the clinical manifestations of DKD (nephromegaly, glomerular hyperfiltration, albuminuria, and kidney failure). Likewise, insulin resistance may underlie the histological manifestations of DKD. Morphological changes of DKD are absent in newly diagnosed type 1 diabetes patients (with no insulin resistance) but appear afterward when insulin resistance develops. In contrast, structural lesions of DKD are typically present before the clinical diagnosis of type 2 diabetes. Several heterogeneous conditions that share the occurrence of insulin resistance, such as aging, obesity, acromegaly, lipodystrophy, cystic fibrosis, insulin receptor dysfunction, and Alström syndrome, also share both clinical and structural manifestations of kidney disease, including glomerulomegaly and other features of DKD, focal segmental glomerulosclerosis, and C3 glomerulopathy, which might be ascribed to the reduction in the synthesis of factor H binding sites (such as heparan sulfate) that leads to uncontrolled complement activation. Alström syndrome patients show systemic interstitial fibrosis markedly similar to that present in diabetes.

In situ assessment of Mindin as a biomarker of podocyte lesions in diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease and end-stage renal failure worldwide. Several mechanisms are involved in the pathogenesis of this disease, which culminate in morphological changes such as podocyte injury. Despite the complex diagnosis and pathogenesis, limited attempts have been made to establish new biomarkers for DN. The higher concentration of Mindin protein in the urine of patients with type 2 diabetes mellitus suggests that it plays a role in DN. Therefore, this study investigated whether in situ protein expression of Mindin can be considered a potential DN biomarker. Fifty renal biopsies from patients diagnosed with DN, 57 with nondiabetic glomerular diseases, including 17 with focal segmental glomerulosclerosis (FSGS), 14 with minimal lesion disease (MLD) and 27 with immunoglobulin A nephropathy (IgAN), and 23 adult kidney samples from autopsies (control group) were evaluated for Mindin expression by immunohistochemistry. Podocyte density was inferred by Wilms' tumor 1 (WT1) immunostaining, while foot process effacement was assessed by transmission electron microscopy. Receiver operative characteristic (ROC) analysis was performed to determine the biomarker sensitivity/specificity. Low podocyte density and increased Mindin expression were observed in all cases of DN, regardless of their class. In the DN group, Mindin expression was significantly higher than that in the FSGS, MCD, IgAN and control groups. Higher Mindin expression was significantly positively correlated with foot process effacement only in class III DN cases. Furthermore, Mindin protein presented high specificity in the biopsies of patients with DN (p < 0.0001). Our data suggest that Mindin may play a role in DN pathogenesis and is a promising biomarker of podocyte lesions.

RISK FACTORS FOR DIABETIC NEPHROPATHY IN DIABETES MELLITUS TYPE 1

OBJECTIVE

The aim: To find the risk factors of microalbuminuria and estimated Glomerular Filtration Rate (eGFR) in patients with type 1 diabetes mellitus.

PATIENTS AND METHODS

Materials and methods: One hundred ten patients of type 1 diabetes mellitus in this cross-sectional study at diabetic and endocrinology center in Al-Najaf during the period from September 2021 to March 2022. All patients were asked about sociodemographic characteristics (age, gender, smoking, duration of DM type1, family history of DM type1), measured (body mass index BMI, blood pressure) and laboratory investigations done to all patients (G.U.E, s. creatinine, lipid profile, HBA1C, calculated estimated Glomerular Filtration Rate (eGFR) and Spot Urine Albumin-Creatinine Ratio (ACR).

RESULTS

Results: Out of 110 patients, 62 male and 48 female, the mean age was (22±12). The patients with microalbuminuria (ACR ≥ 30 mg/g) show statistically significant with increase HBA1C, duration of DM type 1, total cholesterol (T.C), low density lipoprotein (LDL), triglycerides (TG) and family history of DM type 1, while there were not statistically significant with age, gender, smoking, BMI, eGFR, high density lipoprotein (HDL) and hypertension. Patients with eGFR<90mL/min/1.73m2 show statistically significant with increase HBA1C, duration of DM type1, LDL, TG, T.C, while significantly decrease in HDL and there were not statistically significant with age, gender, smoking, family history of DM type 1, BMI and hypertension.

CONCLUSION

Conclusions: The degree of glycemic control, duration of type1 (DM) and dyslipidemia were associated with increased microalbuminuria and reduced eGFR (nephropathy). Family history of DM type1 was risk factor for microalbuminuria.

[Diabetic kidney disease (update 2023) : Position paper of the Austrian Diabetes Association and the Austrian Society for Nephrology]

Epidemiological investigations have shown that approximately 2-3% of all Austrians have diabetes mellitus with renal involvement, leaving 250,000 people in Austria affected. The risk of occurrence and progression of this disease can be attenuated by lifestyle interventions as well as optimization of blood pressure, blood glucose control and special drug classes. The present article represents the joint recommendations of the Austrian Diabetes Association and the Austrian Society of Nephrology for the diagnostic and treatment strategies of diabetic kidney disease.

Study on the relationship between lipoprotein (a) and diabetic kidney disease

OBJECTIVE

Little is currently known about the role of lipid metabolism in diabetic kidney disease (DKD), warranting further study. The present study sought to investigate the correlation between lipid metabolism and renal function as well as renal pathological grade/score in DKD patients.

METHODS

A total of 224 patients diagnosed with DKD by pathological examination were retrospectively analyzed, of which 74 patients were further evaluated by DKD pathological grade/score. ANOVA was used to investigate serum lipoprotein (a) [Lp (a)] levels in DKD patients with different chronic kidney disease (CKD) stages. Spearman correlation analysis was used to evaluate the relationship between Lp (a) and renal function-related indicators. The DKD pathological grade/score was also evaluated with this method. The receiver operating characteristic (ROC) curve was used to analyze the value of Lp (a) in assessing renal function and pathological changes.

RESULTS

There were significant differences in Lp (a) levels among different CKD stages (H = 17.063, p = 0.002) and glomerular grades (H = 12.965, p = 0.005). Lp (a) levels correlated with serum creatinine (p = 0.000), blood urea nitrogen (p = 0.000), estimated glomerular filtration rate (p = 0.000), 24-h proteinuria (24hUPro, p = 0.000), urine microalbumin (p = 0.000), urine albumin creatinine ratio (p = 0.000), glomerular basement membrane thickness (p = 0.003), and glomerular grade (p = 0.039). ROC curve demonstrated good performance of Lp (a) as an indicator to assess CKD stage 4-5 (AUC = 0.684, p = 0.000), 24hUPro > 3.5 g (AUC = 0.720, p = 0.000), and glomerular grade III-IV (AUC = 0.695, p = 0.012).

CONCLUSIONS

Elevated levels of Lp (a) are associated with decreased GFR, increased proteinuria, and renal pathological progression, suggesting they could be used to monitor changes in DKD patients.

Continuous Nursing Intervention Based on Network Interactive in Early Diabetic Kidney Disease Patients

Objective

To analyze the effect of continuous nursing intervention based on network interactive platform on improving blood glucose level and self-efficacy in patients with early diabetic kidney disease.

Methods

The control group received basic routine nursing, and the study group received continuous nursing based on the network interactive platform. The blood glucose level, renal function, inflammatory factors, self-efficacy, self-management behavior, nursing efficacy and adverse reactions were compared.

Results

There was no significant difference in baseline data between the two groups. After the application of continuous nursing based on network interactive platform, the blood glucose level and renal function of patients were significantly decreased, and those of the study group were lower than those of the control group. The inflammatory factors in the study group were significantly lower than those in the control group.

Conclusion

In the nursing of patients with early-onset diabetic kidney disease, the application of continuous nursing based on network interactive platform can effectively reduce the level of inflammatory factors, improve the level of blood glucose and renal function, improve the self-efficacy and self-management behavior of patients, and reduce the occurrence of adverse reactions. It is worthy of promotion and application in nursing.

Optimal peritoneal fluid white blood cell count for diagnosis of peritonitis in peritoneal dialysis patients

BACKGROUND

The diagnosis of peritonitis among peritoneal dialysis (PD) patients is based on clinical presentation, dialysis effluent white blood cell (WBC) count, and dialysis effluent culture. Peritoneal fluid WBC count is very important in the initial diagnosis of peritonitis. The purpose of this work was to determine the optimal number of peritoneal WBCs with different clinical presentations at admission to define PD-related peritonitis.

METHODS

Medical records of chronic PD patients who underwent work-up for suspected peritonitis between 2008 and 2019 were reviewed retrospectively. Results of all peritoneal WBC count tests during this period were collected. Clinical manifestations and follow-up analysis of each peritoneal WBC count were performed.

RESULTS

The peritoneal WBC count cutoff of 100/μL recommended by International Society for Peritoneal Dialysis provided specificity of only 35%. Increasing peritoneal WBC count cutoff to 150, 200, and 250/μL provided sensitivity around 98% and gradually increasing specificity. The chi-square automatic interaction detector model of statistical analysis determined that peritoneal WBC count below 230/μL combined with absence of inflammatory markers (fever, increased C-reactive protein) ruled out peritonitis with 99.8% sensitivity. Peritoneal fluid WBC count cutoff of 230/μL provided specificity of 89% and good positive and negative likelihood scores of 8.3 and 0.03, respectively. Peritoneal fluid polymorphonuclear count has lower discriminating ability for peritonitis compared to peritoneal fluid WBC count.

CONCLUSION

Increasing peritoneal fluid WBC count cutoff to 230/μL in suspected PD-related peritonitis could improve specificity without compromising the sensitivity of the test.

Development and validation of a novel nomogram to predict diabetic kidney disease in patients with type 2 diabetic mellitus and proteinuric kidney disease

PURPOSE

Differentiating between diabetic kidney disease (DKD) and non-diabetic kidney disease (NDKD) in patients with Type 2 diabetes mellitus (T2DM) is important due to implications on treatment and prognosis. Clinical methods to accurately distinguish DKD from NDKD are lacking. We aimed to develop and validate a novel nomogram to predict DKD in patients with T2DM and proteinuric kidney disease to guide decision for kidney biopsy.

METHODS

A hundred and two patients with Type 2 Diabetes Mellitus (T2DM) who underwent kidney biopsy from 1st January 2007 to 31st December 2016 were analysed. Univariate and multivariate analyses were performed to identify predictive variables and construct a nomogram. The discriminative ability of the nomogram was assessed by calculating the area under the receiver operating characteristic curve (AUROC), while calibration was assessed using the Hosmer-Lemeshow goodness-of-fit test and calibration plot. Internal validation of the nomogram was assessed using bootstrap resampling.

RESULTS

Duration of T2DM, HbA1c, absence of hematuria, presence of diabetic retinopathy and absence of positive systemic biomarkers were found to be independent predictors of DKD in multivariate analysis and were represented as a nomogram. The nomogram showed excellent discrimination, with a bootstrap-corrected C statistic of 0.886 (95% CI 0.815-0.956). Both the calibration curve and the Hosmer-Lemeshow goodness-of-fit test (p = 0.242) showed high degree of agreement between the prediction and actual outcome, with the bootstrap bias-corrected curve similarly indicating excellent calibration.

CONCLUSIONS

A novel nomogram incorporating 5 clinical parameters is useful in predicting DKD in type 2 diabetes mellitus patients with proteinuric kidney disease.

A natural products solution to diabetic nephropathy therapy

Diabetic nephropathy is one of the most common complications in diabetes. It has been shown to be the leading cause of end-stage renal disease. However, due to their complex pathological mechanisms, effective therapeutic drugs other than angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), which have been used for 20 years, have not been developed so far. Recent studies have shown that diabetic nephropathy is characterized by multiple signalling pathways and multiple targets, including inflammation, apoptosis, pyroptosis, autophagy, oxidative stress, endoplasmic reticulum stress and their interactions. It definitely exacerbates the difficulty of therapy, but at the same time it also brings out the chance for natural products treatment. In the most recent two decades, a large number of natural products have displayed their potential in preclinical studies and a few compounds are under invetigation in clinical trials. Hence, many compounds targeting these singals have been emerged as a comprehensive blueprint for treating strategy of diabetic nephropathy. This review focuses on the cellular and molecular mechanisms of natural prouducts that alleviate this condition, including preclinical studies and clinical trials, which will provide new insights into the treatment of diabetic nephropathy and suggest novel ideas for new drug development.

A kidney proximal tubule model to evaluate effects of basement membrane stiffening on renal tubular epithelial cells

The kidney tubule consists of a single layer of epithelial cells supported by the tubular basement membrane (TBM), a thin layer of specialized extracellular matrix (ECM). The mechanical properties of the ECM are important for regulating a wide range of cell functions including proliferation, differentiation and cell survival. Increased ECM stiffness plays a role in promoting multiple pathological conditions including cancer, fibrosis and heart disease. How changes in TBM mechanics regulate tubular epithelial cell behavior is not fully understood. Here we introduce a cell culture system that utilizes in vivo-derived TBM to investigate cell-matrix interactions in kidney proximal tubule cells. Basement membrane mechanics was controlled using genipin, a biocompatibility crosslinker. Genipin modification resulted in a dose-dependent increase in matrix stiffness. Crosslinking had a marginal but statistically significant impact on the diffusive molecular transport properties of the TBM, likely due to a reduction in pore size. Both native and genipin-modified TBM substrates supported tubular epithelial cell growth. Cells were able to attach and proliferate to form confluent monolayers. Tubular epithelial cells polarized and assembled organized cell-cell junctions. Genipin modification had minimal impact on cell viability and proliferation. Genipin stiffened TBM increased gene expression of pro-fibrotic cytokines and altered gene expression for N-cadherin, a proximal tubular epithelial specific cell-cell junction marker. This work introduces a new cell culture model for cell-basement membrane mechanobiology studies that utilizes in vivo-derived basement membrane. We also demonstrate that TBM stiffening affects tubular epithelial cell function through altered gene expression of cell-specific differentiation markers and induced increased expression of pro-fibrotic growth factors.

Urinary N-acetyl-β-d-glucosaminidase-creatine ratio is a valuable predictor for advanced diabetic kidney disease

BACKGROUND

Many biomarkers show high diagnostic values for diabetic kidney disease (DKD), but fewer studies focus on the predictive assessment of DKD progression by blood and urinary biomarkers.

AIM

This study aims to find powerful risk predictors and identifying biomarkers in blood and urine for DKD progression.

METHODS

A total of 117 patients with type 2 DKD including early and advanced stages and their laboratory parameters were statistically assessed. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the significance of discriminating between early and advanced DKD, and the predictive power for advanced DKD was analyzed by regression analysis and trisector grouping.

RESULTS

N-acetyl-β-d-glucosaminidase-creatine (NAG/CR) level in advanced DKD was statistically higher than that in early DKD (p < 0.05), and there was a higher incidence of advanced DKD (72% vs. 56%) and high odds ratio (OR: 3.917, 95% CI: 1.579-10.011) of NAG/CR with ≥2.79 U/mmol compared with <2.79 U/mmol (p < 0.05). NAG/CR ratio also showed a higher area under the ROC curve of 0.727 (95% CI: 0.616-0.828, p = 0.010) with a high sensitivity (0.75) and a moderate specificity (0.66) when 1.93 U/mmol was set as the optimal cutoff value. The adjusted-multivariable analysis revealed that NAG/CR had an OR of 1.021 (95% CI: 1.024-1.038) and 2.223 (95% CI: 1.231-4.463) based on a continuous and categorical variable, respectively, for risk of advanced DKD. Moreover, the prevalence of advanced DKD exhibited an increasing tendency by an increment of the trisector of NAG/CR.

CONCLUSIONS

This study suggests that NAG/CR ratio is an independent predictor for advanced DKD, and it also can be used as a powerful identifying marker between early and advanced DKD.

Whether Renal Pathology Is an Independent Predictor for End-Stage Renal Disease in Diabetic Kidney Disease Patients with Nephrotic Range Proteinuria: A Biopsy-Based Study

Aims: To investigate whether renal pathology is an independent predictor for end-stage renal disease (ESRD) in diabetic kidney diseases (DKD) with nephrotic range proteinuria. Methods: A total of 199 DKD patients with nephrotic range proteinuria underwent renal biopsy and were divided into an ESRD group and a non-ESRD group. A Kaplan−Meier analysis was used to compare renal survival rate, and univariate and multivariate Cox proportional hazard analyses were used to determine the predictors of the ESRD. Results: The mean age of included patients was 51.49 ± 9.12 years and 113 patients (56.8%) progressed to ESRD. The median follow-up period was 16 (12−28) months. The glomerular pathology class III is the most common type (54.3%). In the Kaplan−Meier analysis, compared with patients without ESRD, patients with ESRD had a longer duration of diabetes (≥6 years), lower eGFR (<60 mL/min/1.73 m2), lower albumin (<30 g/L), lower hemoglobin (<120 g/L), and a higher grade of glomerular stage (class III + IV vs. class I + II) (p < 0.05). The hemoglobin and e-GFR, but not the histopathological damage, were significantly associated with a higher risk of ESRD in both the univariate and multivariate Cox analyses. Conclusions: In patients with diabetic kidney disease characterized by nephrotic range proteinuria, histopathological damage (glomerular alterations, interstitial fibrosis and tubular atrophy (IFTA), interstitial inflammation, and arteriolar hyalinosis) is not associated with poor renal outcomes, but hemoglobin and e-GFR could predict poor renal outcomes.