Review of potential biomarkers of inflammation and kidney injury in diabetic kidney disease

Associations of Kidney Tubular Biomarkers With Incident Macroalbuminuria and Sustained Low eGFR in DCCT/EDIC

OBJECTIVE

Tubulointerstitial injury contributes to diabetic kidney disease (DKD) progression. We tested tubular biomarker associations with DKD development in type 1 diabetes (T1D).

RESEARCH DESIGN AND METHODS

We performed a case-cohort study examining associations of tubular biomarkers, measured across seven time points spanning ∼30 years, with incident macroalbuminuria ("severely elevated albuminuria," urinary albumin excretion rate [AER] ≥300 mg/day) and sustained low estimated glomerular filtration rate (eGFR) (persistent eGFR <60 mL/min/1.73 m2) in the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study. Biomarkers included KIM-1 and sTNFR1 in serum/plasma, MCP-1 and EGF in urine, and a composite tubular secretion score reflecting secreted solute clearance. We assessed biomarkers using single values, as mean values from consecutive time points, and as change over consecutive time points, each as time-updated exposures.

RESULTS

At baseline, mean diabetes duration was 5.9 years, with mean HbA1c 8.9%, eGFR 125 mL/min/1.73 m2, and AER 16 mg/day. There were 4.8 and 3.5 cases per 1,000 person-years of macroalbuminuria and low eGFR, respectively. Assessed according to single biomarker values, KIM-1 was associated with risk of subsequent macroalbuminuria and low eGFR (hazard ratio [HR] per 20% higher biomarker 1.11 [95% CI 1.06, 1.16] and 1.12 [1.04, 1.21], respectively) and sTNFR1 was associated with subsequent macroalbuminuria (1.14 [1.03, 1.25]). Mean KIM-1 and EGF-to-MCP-1 ratio were associated with subsequent low eGFR. In slope analyses, increases in KIM-1 and sTNFR1 were associated with subsequent macroalbuminuria (per 20% biomarker increase, HR 1.81 [1.40, 2.34] and 1.95 [1.18, 3.21]) and low eGFR (2.26 [1.65, 3.09] and 2.94 [1.39, 6.23]).

CONCLUSIONS

Serial KIM-1 and sTNFR1 are associated with incident macroalbuminuria and sustained low eGFR in T1D.

Serum high mobility group box 1 as a potential biomarker for the progression of kidney disease in patients with type 2 diabetes

Background

As a damage-associated molecular pattern protein, high mobility group box 1 (HMGB1) is associated with kidney and systemic inflammation. The predictive and therapeutic value of HMGB1 as a biomarker has been confirmed in various diseases. However, its value in diabetic kidney disease (DKD) remains unclear. Therefore, this study aimed to investigate the correlation between serum and urine HMGB1 levels and DKD progression.

Methods

We recruited 196 patients with type 2 diabetes mellitus (T2DM), including 109 with DKD and 87 T2DM patients without DKD. Additionally, 60 healthy participants without T2DM were also recruited as controls. Serum and urine samples were collected for HMGB1 analysis. Simultaneously, tumor necrosis factor receptor superfamily member 1A (TNFR-1) in serum and kidney injury molecule (KIM-1) in urine samples were evaluated for comparison.

Results

Serum and urine HMGB1 levels were significantly higher in patients with DKD than in patients with T2DM and healthy controls. Additionally, serum HMGB1 levels significantly and positively correlated with serum TNFR-1 (R 2 = 0.567, p<0.001) and urine KIM-1 levels (R 2 = 0.440, p<0.001), and urine HMGB1 has a similar correlation. In the population with T2DM, the risk of DKD progression increased with an increase in serum HMGB1 levels. Multivariate logistic regression analysis showed that elevated serum HMGB1 level was an independent risk factor for renal function progression in patients with DKD, and regression analysis did not change in the model corrected for multiple variables. The restricted cubic spline depicted a nonlinear relationship between serum HMGB1 and renal function progression in patients with DKD (p-nonlinear=0.007, p<0.001), and this positive effect remained consistent across subgroups.

Conclusion

Serum HMGB1 was significantly correlated with DKD and disease severity. When the HMGB1 level was ≥27 ng/ml, the risk of renal progression increased sharply, indicating that serum HMGB1 can be used as a potential biomarker for the diagnosis of DKD progression.

Association of Systemic Immune-Inflammation Index and Systemic Inflammation Response Index with Diabetic Kidney Disease in Patients with Type 2 Diabetes Mellitus

Purpose

To evaluate the association of the systemic immune-inflammatory index (SII) and systemic inflammatory response index (SIRI) with the clinical and pathological features and progression of diabetic kidney disease (DKD).

Patients and Methods

We analyzed 303 patients with type 2 diabetes mellitus (T2DM), classifying them into distinct groups: T2DM, early DKD (EDKD), and clinical DKD (Cli-DKD). Variations in SII and SIRI levels across these groups and their association with renal function were assessed. Logistic regression analysis was used to identify independent risk factors for DKD. Additionally, in 43 patients with biopsy-confirmed DKD, we analyzed the relationship between SII, SIRI, and pathological changes. Kaplan-Meier survival analysis and the Cox proportional hazards model were used to assess the influence of SII and SIRI levels on outcomes in patients with DKD.

Results

SII and SIRI were significantly higher in the Cli-DKD group than in the T2DM and EDKD groups, and were positively correlated with the urinary albumin-creatinine ratio and negatively correlated with estimated glomerular filtration rate. Notably, SIRI was identified as an independent risk factor for DKD development. Additionally, a lower SII score was associated with a higher cumulative survival rate.

Conclusion

This study demonstrates an association between SII, SIRI, and renal function in patients with T2DM. A high SIRI was an independent risk factor for DKD, while an elevated SII was associated with an increased risk of kidney disease progression in biopsy-confirmed DKD cases. Our findings underscore the potential implications of utilizing SII and SIRI as cost-effective and readily available inflammatory indicators for monitoring DKD in primary care settings.

The Molecular Mechanism of Renal Tubulointerstitial Inflammation Promoting Diabetic Nephropathy

Diabetic nephropathy (DN) is a common complication affecting many diabetic patients, leading to end-stage renal disease. However, its pathogenesis still needs to be fully understood to enhance the effectiveness of treatment methods. Traditional theories are predominantly centered on glomerular injuries and need more explicit explanations of recent clinical observations suggesting that renal tubules equally contribute to renal function and that tubular lesions are early features of DN, even occurring before glomerular lesions. Although the conventional view is that DN is not an inflammatory disease, recent studies indicate that systemic and local inflammation, including tubulointerstitial inflammation, contributes to the development of DN. In patients with DN, intrinsic tubulointerstitial cells produce many proinflammatory factors, leading to medullary inflammatory cell infiltration and activation of inflammatory cells in the interstitial region. Therefore, understanding the molecular mechanism of renal tubulointerstitial inflammation contributing to DN injury is of great significance and will help further identify key factors regulating renal tubulointerstitial inflammation in the high glucose environment. This will aid in developing new targets for DN diagnosis and treatment and expanding new DN treatment methods.

Currently Used Methods to Evaluate the Efficacy of Therapeutic Drugs and Kidney Safety

Kidney diseases with kidney failure or damage, such as chronic kidney disease (CKD) and acute kidney injury (AKI), are common clinical problems worldwide and have rapidly increased in prevalence, affecting millions of people in recent decades. A series of novel diagnostic or predictive biomarkers have been discovered over the past decade, enhancing the investigation of renal dysfunction in preclinical studies and clinical risk assessment for humans. Since multiple causes lead to renal failure, animal studies have been extensively used to identify specific disease biomarkers for understanding the potential targets and nephropathy events in therapeutic insights into disease progression. Mice are the most commonly used model to investigate the mechanism of human nephropathy, and the current alternative methods, including in vitro and in silico models, can offer quicker, cheaper, and more effective methods to avoid or reduce the unethical procedures of animal usage. This review provides modern approaches, including animal and nonanimal assays, that can be applied to study chronic nonclinical safety. These specific situations could be utilized in nonclinical or clinical drug development to provide information on kidney disease.

IgG N-glycans are associated with prevalent and incident complications of type 2 diabetes

AIMS/HYPOTHESIS

Inflammation is important in the development of type 2 diabetes complications. The N-glycosylation of IgG influences its role in inflammation. To date, the association of plasma IgG N-glycosylation with type 2 diabetes complications has not been extensively investigated. We hypothesised that N-glycosylation of IgG may be related to the development of complications of type 2 diabetes.

METHODS

In three independent type 2 diabetes cohorts, plasma IgG N-glycosylation was measured using ultra performance liquid chromatography (DiaGene n = 1815, GenodiabMar n = 640) and mass spectrometry (Hoorn Diabetes Care Study n = 1266). We investigated the associations of IgG N-glycosylation (fucosylation, galactosylation, sialylation and bisection) with incident and prevalent nephropathy, retinopathy and macrovascular disease using Cox- and logistic regression, followed by meta-analyses. The models were adjusted for age and sex and additionally for clinical risk factors.

RESULTS

IgG galactosylation was negatively associated with prevalent and incident nephropathy and macrovascular disease after adjustment for clinical risk factors. Sialylation was negatively associated with incident diabetic nephropathy after adjustment for clinical risk factors. For incident retinopathy, similar associations were found for galactosylation, adjusted for age and sex.

CONCLUSIONS

We showed that IgG N-glycosylation, particularly galactosylation and to a lesser extent sialylation, is associated with a higher prevalence and future development of macro- and microvascular complications of diabetes. These findings indicate the predictive potential of IgG N-glycosylation in diabetes complications and should be analysed further in additional large cohorts to obtain the power to solidify these conclusions.

Biomarkers of the End-Stage Renal Disease Progression: Beyond the GFR

Chronic kidney disease can progress to the end-stage renal disease (ESRD) characterized by a high risk of morbidity and mortality. ESRD requires immediate therapy or even dialysis or kidney transplantation, therefore, its timely diagnostics is critical for many patients. ESRD is associated with pathological changes, such as inflammation, fibrosis, endocrine disorders, and epigenetic changes in various cells, which could serve as ESRD markers. The review summarizes information on conventional and new ESRD biomarkers that can be assessed in kidney tissue, blood, and urine. Some biomarkers are specific to a particular pathology, while others are more universal. Here, we suggest several universal inflammatory, fibrotic, hormonal, and epigenetic markers indicative of severe deterioration of renal function and ESRD progression for improvement of ESRD diagnostics.

Association between a high triglyceride-glucose index and chronic kidney disease in adult patients with latent autoimmune diabetes

BACKGROUND

Insulin resistance (IR) is one of the risk factors for chronic kidney disease (CKD) and diabetes. The triglyceride-glucose (TyG) index is considered a reliable alternative marker of IR. We investigated the correlation between the TyG index and the severity of CKD in patients with latent autoimmune diabetes in adults (LADA).

METHODS

This cross-sectional study included 288 patients with LADA in the department of endocrinology at our hospital between January 2018 and January 2022. The TyG index was calculated as Ln [TG (mg/dl) × fasting blood glucose (FBG) (mg/dl) / 2]. All individuals were divided into either a LADA + CKD group or a LADA + non-CKD group according to the presence or absence of CKD. A correlation analysis, logistic regression analysis and receiver operating characteristics curve analysis were performed.

RESULTS

A total of 130 (45.1%) participants were identified as having CKD. Compared with the non-CKD group, the CKD group had a longer disease duration and a higher proportion of smokers; patients were more likely to have hypertension and higher serum creatinine, triglyceride, cholesterol, low-density lipoprotein cholesterol, FBG, uric acid estimated glomerular filtration rates (eGFR) and TyG levels as well as lower high-density lipoprotein cholesterol levels (all P < 0.05). The positive relationship between the TyG index and the urinary albumin/creatinine ratio was significant (r = 0.249, P = 0.010). There was also a significant correlation between the TyG index and the eGFR (r = - 0.211, P = 0.034) after adjusting for confounding factors. The area-under-the-curve value of the TyG index was 0.708 (95% confidence interval: 0.61-0.81, P < 0.001).

CONCLUSIONS

The TyG index is significantly associated with the severity of CKD in patients with LADA. This conclusion supports the clinical application of the TyG index for the assessment of kidney disease in patients with LADA.

Effects of Glycemic Variability on Regulatory T Cells in Patients with Type 2 Diabetes and Kidney Disease

Purpose

To investigate the pathogenesis of diabetic kidney disease (DKD) in type 2 diabetes mellitus (T2DM), we evaluated the effects of short-term glycemic variability (GV) on the profile of T cell subpopulations.

Methods

A total of 47 T2DM patients with normoalbuminuria, 47 microalbuminuria, and 49 macroalbuminuria were enrolled. The continuous glucose monitoring (CGM) determined the GV of enrolled patients. Flow cytometry was used to determine the proportion of T cell subpopulations.

Results

The frequency of T helper (Th) 17 and Th1 cells significantly increased while regulatory T cells (Tregs) significantly decreased in the macroalbuminuria group compared to normoalbuminuria and microalbuminuria groups (P < 0.01). The suppressive function of Tregs was significantly lower in the macroalbuminuria group than the normoalbuminuria group (P < 0.05). Compared with the normoalbuminuria group, the mean amplitude of glucose excursions (MAGE) of the macroalbuminuria group was significantly higher (P<0.05). Furthermore, there were negative associations between the proportion of Tregs and MAGE.

Conclusions

Increased GV could decrease the proportion of Tregs and may impair their function. This may lead to increases in Th1 and Th17 cells, and some inflammatory cytokines, which might contribute to the development and progression of DKD in T2DM.

Lupenone improves type 2 diabetic nephropathy by regulating NF-κB pathway-mediated inflammation and TGF-β1/Smad/CTGF-associated fibrosis

BACKGROUND

Type 2 diabetic nephropathy is a common diabetic complication and the main cause of death in patients with diabetes. Research has aimed to find an ideal drug with minimal side effects for treating this disease. Banana peel has been shown to be anti-diabetic, with lupenone isolated from banana peel exhibiting antidiabetic and anti-inflammatory activities; However, the effects of lupenone on type 2 diabetic nephropathy are largely unknown.

PURPOSE

This study aimed to investigate the ameliorative effect of lupenone on type 2 diabetic nephropathy, and its mechanism from both anti-inflammatory and anti-fibrotic perspectives.

METHODS

Spontaneous type 2 diabetic nephropathy db/db mouse models were given three levels of lupenone (24 or 12 or 6 mg/kg/d) via intragastric administration for six weeks, and irbesartan treatment was used for the positive control group. We explored the effects and mechanism of lupenone action using enzyme-linked immunosorbent assay, automatic biochemical analyzer, hematoxylin-eosin and Masson staining, real time-PCR, and western blotting. Concurrently, a high-sugar and high-fat diet combined with a low-dose streptozotocin-induced type 2 diabetic nephropathy rat model was used for confirmatory research.

RESULTS

Lupenone administration maintained the fasting blood glucose; reduced glycosylated hemoglobin, insulin, and 24 h proteinuria levels; and markedly regulated changes in biochemical indicators associated with kidney injury in serum and urine (including 24 h proteinuria, micro-albumin, N-acetyl-β-d-glucosaminidase, α1-micro-globulin, creatinine, urea nitrogen, uric acid, total protein, and albumin) of type 2 diabetic nephropathy mice and rats. Hematoxylin-eosin and Masson staining as well as molecular biology tests revealed that inflammation and fibrosis are the two key processes affected by lupenone treatment. Lupenone protected type 2 diabetic nephropathy kidneys by regulating the NF-κB-mediated inflammatory response and TGF-β1/Smad/CTGF pathway-associated fibrosis.

CONCLUSION

Lupenone has potential as an innovative drug for preventing and treating diabetic nephropathy. Additionally, it has great value for the utilization of banana peel resources.

Diagnostic and prognostic biomarkers for tubulointerstitial fibrosis

Renal fibrosis is the final common pathophysiological pathway in chronic kidney disease (CKD) regardless of the underlying cause of kidney injury. Tubulointerstitial fibrosis (TIF) is considered to be the key pathological predictor of CKD progression. Currently, the gold-standard tool to identify TIF is kidney biopsy, an invasive method that carries risks. Non-invasive diagnostics rely on an estimation of glomerular filtration rate and albuminuria to assess kidney function, but these fail to diagnose early CKD accurately or to predict progressive decline in kidney function. In this review, we summarize the current and emerging molecular biomarkers that have been studied in various clinical settings and in animal models of kidney disease and that are correlated with the degree of TIF. We examine the potential of these biomarkers to diagnose TIF non-invasively and to predict disease progression. We also examine the potential of new technologies and non-invasive diagnostic approaches in assessing TIF. Limitations of current and potential biomarkers are discussed and knowledge gaps identified.

Au@NiFeMOFs as the signal quencher of Au@g-C3N4NSs composite for sensitive "on-off" electrochemiluminescence immunosensing of beta-2-microglobulin

In this study, an electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor was constructed to detect beta-2-microglobulin (B2M). As a donor-acceptor pair, a carbon nitride nanosheet modified with gold nanoparticles (Au@g-C₃N₄NSs) and a nickel- and iron-based organic framework modified with gold nanoparticles (Au@NiFeMOFs) were prepared. The sandwich immunosensor was successfully constructed so that ECL-RET occurred between Au@NiFeMOFs and Au@g-C₃N₄NSs. The ECL intensity of the immunosensor decreased with the increase the B2M concentration due to the low conductivity of B2M. The linear range of the ECL-RET immunosensor was from 10 fg/mL to 10 ng/mL, and the limit of detection was 2.3 fg/mL (S/N = 3). The developed immunosensor had high sensitivity, high specificity, and excellent stability. It could realize the sensitivity test of B2M and provide a novel idea for the detection of biomarkers.

Identification of a novel immune landscape signature as effective diagnostic markers related to immune cell infiltration in diabetic nephropathy

Background

The study aimed to identify core biomarkers related to diagnosis and immune microenvironment regulation and explore the immune molecular mechanism of diabetic nephropathy (DN) through bioinformatics analysis.

Methods

GSE30529, GSE99325, and GSE104954 were merged with removing batch effects, and different expression genes (DEGs) were screened at a criterion |log2FC| &gt;0.5 and adjusted P &lt;0.05. KEGG, GO, and GSEA analyses were performed. Hub genes were screened by conducting PPI networks and calculating node genes using five algorithms with CytoHubba, followed by LASSO and ROC analysis to accurately identify diagnostic biomarkers. In addition, two different GEO datasets, GSE175759 and GSE47184, and an experiment cohort with 30 controls and 40 DN patients detected by IHC, were used to validate the biomarkers. Moreover, ssGSEA was performed to analyze the immune microenvironment in DN. Wilcoxon test and LASSO regression were used to determine the core immune signatures. The correlation between biomarkers and crucial immune signatures was calculated by Spearman analysis. Finally, cMap was used to explore potential drugs treating renal tubule injury in DN patients.

Results

A total of 509 DEGs, including 338 upregulated and 171 downregulated genes, were screened out. “chemokine signaling pathway” and “cell adhesion molecules” were enriched in both GSEA and KEGG analysis. CCR2, CX3CR1, and SELP, especially for the combination model of the three genes, were identified as core biomarkers with high diagnostic capabilities with striking AUC, sensitivity, and specificity in both merged and validated datasets and IHC validation. Immune infiltration analysis showed a notable infiltration advantage for APC co-stimulation, CD8+ T cells, checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation in the DN group. In addition, the correlation analysis showed that CCR2, CX3CR1, and SELP were strongly and positively correlated with checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation in the DN group. Finally, dilazep was screened out as an underlying compound for DN analyzed by CMap.

Conclusions

CCR2, CX3CR1, and SELP are underlying diagnostic biomarkers for DN, especially in their combination. APC co-stimulation, CD8+ T cells, checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation may participate in the occurrence and development of DN. At last, dilazep may be a promising drug for treating DN.