Neutrophil Gelatinase-associated Lipocalin: As a Predictor of Early Diabetic Nephropathy in Type 2 Diabetes Mellitus

Changes in Urinary NGAL, FN, and LN Excretion in Type 2 Diabetic Patients Following Anti-Diabetic Therapy with Metformin

Background: Excessive accumulation of glomerular extracellular matrix (ECM) is a key factor in the development and progression of diabetic nephropathy (DN). As kidney dysfunction has been reported in normoalbuminuric patients, identifying novel diagnostic and prognostic markers is essential for the prevention and treatment of DN. Methods: Urinary excretion of neutrophil gelatinase-associated lipocalin (NGAL) and ECM-related glycoproteins, i.e., fibronectin (FN) and laminin (LN), was measured in obese patients with newly diagnosed type 2 diabetes mellitus (T2DM) before and after 6 months of metformin therapy. Results: Baseline NGAL (1.27 (0.80-2.36) ng/mg Cr), FN (11.19 (5.31-21.56) ng/mg Cr) and LN (123.17 (54.56-419.28) pg/mg Cr) levels did not significantly differ between T2DM patients and controls (1.95 (1.09-2.97) ng/mg Cr, 11.94 (7.78-18.01) ng/mg Cr and 157.85 (83.75-326.40) pg/mg Cr, respectively). In multivariate regression analysis, the body mass index was identified as the only significant predictor influencing urinary NGAL and FN levels at baseline, with β = 0.249, p = 0.005 and β = 1.068, p = 0.010, respectively. Metformin treatment significantly increased urinary levels of both ECM proteins, i.e., FN (18.48 (11.64-32.46) ng/mg Cr) and LN (179.51 (106.22-414.68) pg/mg Cr), without any effect on NGAL levels (1.44 (0.81-2.72) ng/mg Cr). FN and LN were positively associated with NGAL both before (r = 0.709 and r = 0.646, both p < 0.001, respectively) and after (r = 0.594 and r = 0.479, both p < 0.001, respectively) therapy. No correlations were found between NGAL, FN, LN, and albuminuria. However, NGAL was positively correlated with the albumin/creatinine ratio (ACR) both before (r = 0.323, p < 0.05) and after (r = 0.287, p < 0.05) therapy, and negatively with estimated glomerular filtration rate (eGFR) in pre-treatment diabetics (r = -0.290, p < 0.05). FN and LN were also correlated with ACR (r = 0.384, p < 0.01 and r = 0.470, p < 0.001), although the association for LN was limited to untreated patients (r = 0.422, p < 0.01). Conclusions: Our results suggest that metformin has a beneficial effect on ECM turnover with a significant increase in urinary excretion of non-collagenous markers of glomerular injury, i.e., FN and LN. Additionally, ECM-related markers may serve as useful tools for monitoring early renal injury in obese diabetic patients.

Obesity-Related Chronic Kidney Disease: From Diagnosis to Treatment

Obesity has emerged as a global epidemic with far-reaching health complications, including its role as an independent risk factor for chronic kidney disease (CKD). Increasing evidence suggests that obesity contributes to CKD through multiple mechanisms, including chronic inflammation, hemodynamic alterations, insulin resistance, and lipid accumulation. These processes can culminate in histopathological changes collectively referred to as obesity-related glomerulopathy (ORG). This review aims to provide a comprehensive overview of the current knowledge regarding the prevalence, clinical manifestations, and pathophysiology of ORG. Furthermore, we emphasize the importance of identifying key biomarkers that facilitate the early detection of ORG. Finally, we explore emerging therapeutic strategies that offer promise in mitigating this growing global health crisis.

Neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, and periostin: Novel urinary biomarkers in diabetic nephropathy

BACKGROUND

Globally, diabetic nephropathy (DN) is the primary cause of chronic kidney disease. Currently, renal function is monitored indirectly using measures of serum creatinine, estimated glomerular filtration rate (eGFR), and proteinuria. Novel urinary biomarkers utilized in the early stages of DN have been described; these indicators can be used in the early identification of the disease, which is important for initiating treatment to halt or impediment the advance of diabetic nephropathy.

AIM

To estimate neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and periostin (POSTN) levels as novel urinary biomarkers in DN.

METHODS

In this hospital based cross-sectional study, a total of 160 patients of both genders aged 18 years or more; 40 healthy participants and 120 patients with diabetes mellitus (DM) were included. Patients with DM were divided into normoalbuminuria (n = 40), microalbuminuria (n = 40), and macroalbuminuria (n = 40) groups as per urine albumin creatinine ratio (uACR). Blood urea, serum creatinine, uACR were measured. Urine NGAL, KIM-1, and POSTN were measured by enzyme linked immunosorbent assay. The eGFR was calculated and compared with urinary markers.

RESULTS

NGAL, KIM-1, and POSTN levels increased significantly in normo, micro, and macroalbuminuria with the highest in the macroalbuminuria group. Albumin creatinine ratio (ACR) showed a positive correlation with NGAL, KIM-1, and POSTN levels. The eGFR showed a weak negative correlation with ACR, NGAL, KIM-1, and POSTN. NGAL was significantly lower in stage 1 compared to stage 2, 3, and 4 kidney disease. KIM-1 was significantly decreased in stage 1 compared to stage 4 kidney disease. POSTN was significantly decreased in stage 1 compared to stage 3 and 4 kidney disease. The receiver operator curve analysis of ACR, NGAL, KIM-1, and POSTN showed good sensitivity of 80%, 75.8%, 63.3%, and 80 % respectively with a cut-off of 12.5 mg/g, 4.5 μg/L, 1.5 ng/mL, and 37.5 ng/mL.

CONCLUSION

Urinary NGAL and POSTN are independent markers of DN.

Elevated ALOX12 in renal tissue predicts progression in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the major causes of end-stage renal disease and one of the significant complications of diabetes. This study aims to identify the main differentially expressed genes in DKD from transcriptome sequencing results and analyze their diagnostic value. The present study sequenced db/m mouse and db/db mouse to determine the ALOX12 genetic changes related to DKD. After preliminary validation, ALOX12 levels were significantly elevated in the blood of DKD patients, but not during disease progression. Moreover, urine ALOX12 was increased only in macroalbuminuria patients. Therefore, to visualize the diagnostic efficacy of ALOX12 on the onset and progression of renal injury in DKD, we collected kidney tissue from patients for immunohistochemical staining. ALOX12 was increased in the kidneys of patients with DKD and was more elevated in macroalbuminuria patients. Clinical chemical and pathological data analysis indicated a correlation between ALOX12 protein expression and renal tubule injury. Further immunofluorescence double staining showed that ALOX12 was expressed in both proximal tubules and distal tubules. Finally, the diagnostic value of the identified gene in the progression of DKD was assessed using receiver operating characteristic (ROC) curve analysis. The area under the curve (AUC) value for ALOX12 in the diagnosis of DKD entering the macroalbuminuria stage was 0.736, suggesting that ALOX12 has good diagnostic efficacy. During the development of DKD, the expression levels of ALOX12 in renal tubules were significantly increased and can be used as one of the predictors of the progression to macroalbuminuria in patients with DKD.

Six months of physical inactivity is insufficient to cause chronic kidney disease in C57BL/6J mice

Chronic kidney disease (CKD) is a progressive disorder marked by a decline in kidney function. Obesity and sedentary behavior contribute to the development of CKD, though mechanisms by which this occurs are poorly understood. This knowledge gap is worsened by the lack of a reliable murine CKD model that does not rely on injury, toxin, or gene deletion to induce a reduction in kidney function. High-fat diet (HFD) feeding alone is insufficient to cause reduced kidney function until later in life. Here, we employed a small mouse cage (SMC), a recently developed mouse model of sedentariness, to study its effect on kidney function. Wildtype C57BL/6J male mice were housed in sham or SMC housing for six months with HFD in room (22°C) or thermoneutral (30°C) conditions. Despite hyperinsulinemia induced by the SMC+HFD intervention, kidneys from these mice displayed normal glomerular filtration rate (GFR). However, the kidneys showed early signs of kidney injury, including increases in Col1a1 and NGAL transcripts, as well as fibrosis by histology, primarily in the inner medullary/papilla region. High-resolution respirometry and fluorometry experiments showed no statistically significant changes in the capacities for respiration, ATP synthesis, or electron leak. These data confirm the technical challenge in modeling human CKD. They further support the notion that obesity and a sedentary lifestyle make the kidneys more vulnerable, but additional insults are likely required for the pathogenesis of CKD.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) as a potential early biomarker for diabetic nephropathy: a meta-analysis

BACKGROUND

Diabetic nephropathy (DN) is a prevalent and chronic, severe complication of diabetes, representing a serious global health concern. Early detection of DN is essential for initiating timely and effective therapeutic interventions and accurately assessing prognosis. Neutrophil Gelatinase-Associated Lipocalin (NGAL), a low molecular weight protein, has emerged as a potential biomarker for DN due to its association with renal injury and its ability to provide early indications of kidney damage. NGAL levels in both serum and urine are elevated in individuals with renal damage, making it a valuable biomarker for detecting early signs of kidney impairment in the context of diabetes. This study aims to investigate the utility of NGAL as an early biomarker for DN and explore its correlation with various clinical parameters associated with the disease. Understanding the relationship between NGAL levels and clinical parameters such as glycemic control, renal function, blood pressure, and duration of diabetes is crucial for comprehensively evaluating the potential of NGAL as a diagnostic and prognostic tool for DN. Furthermore, assessing the sensitivity and specificity of NGAL in detecting early-stage DN will provide valuable insights into its clinical applicability and reliability.

METHODOLOGY

A planned meta-analysis was conducted following PRISMA and MOOSE guidelines. The PubMed database was searched from January 2016 to June 2023 for English-language studies on DN and NGAL. Fifteen eligible studies were included as per the criteria. Data on serum NGAL levels in DN patients and healthy controls were analyzed using Stata 16.0 software.

RESULT

The study revealed a significantly higher mean serum NGAL level in DN patients (168.08 ng/ml, 95% CI: 105.50-230.67) compared to healthy controls (75.02 ng/ml, 95% CI: 43.02-107.03), demonstrating NGAL's potential as a biomarker (P=0.01).

CONCLUSION

NGAL offers a powerful tool for DN diagnosis, staging, and monitoring, surpassing traditional markers in sensitivity. Challenges include defining universal threshold values and ensuring consistent test performance across diverse clinical settings. The study underscores NGAL's potential in transforming DN diagnosis and management.

Renoprotective Potency of Sitagliptin versus Pioglitazone in Type 2 Diabetic Patients: Impact on LncMIAT

Background: Diabetes mellitus (DM) represents one of the most important reasons for chronic kidney diseases due to the high level of blood glucose that destructs blood vessels. Objective: The present study focused on investigating the protective impact of sitagliptin on kidney complication in type 2 diabetes mellitus (T2DM) patients in comparison to pioglitazone to examine which has the superior effect against the nephritic complication of DM. Methods: Eighty adult subjects were classified into four groups: control group, pioglitazone-treated T2DM patients (P group), sitagliptin-treated T2DM patients for less than one year (SL group), and sitagliptin-treated T2DM patients for more than one year (SM group). Blood samples were withdrawn from all subjects for analysis of neutrophil gelatinase-associated lipocalin (NGAL), vanin-1, kidney injury molecule-1 (KIM-1), glyoxalase-1 (Glo-1), methylglyoxal (MG), cystatin-C, and interleukin-18 (IL-18) using competitive ELISA kits. Also, long noncoding myocardial infarction associated transcript (lncMIAT) was measured in whole blood using qRT-PCR. Results: The present study revealed that the lncMIAT expression level was significantly higher in the P group as compared to the SL group, SM group, or healthy control group. Additionally, serum NGAL, vanin-1, KIM-1, Glo-1, MG, and cystatin-C were significantly higher in the P group and SL group as compared to the SM group and healthy control group. Conclusion: Sitagliptin protected the kidney through downregulation of lncMIAT besides amelioration of kidney injury marker levels, which was more preferable than in pioglitazone therapy.

Advances in understanding and treating diabetic kidney disease: focus on tubulointerstitial inflammation mechanisms

Diabetic kidney disease (DKD) is a serious complication of diabetes that can lead to end-stage kidney disease. Despite its significant impact, most research has concentrated on the glomerulus, with little attention paid to the tubulointerstitial region, which accounts for the majority of the kidney volume. DKD's tubulointerstitial lesions are characterized by inflammation, fibrosis, and loss of kidney function, and recent studies indicate that these lesions may occur earlier than glomerular lesions. Evidence has shown that inflammatory mechanisms in the tubulointerstitium play a critical role in the development and progression of these lesions. Apart from the renin-angiotensin-aldosterone blockade, Sodium-Glucose Linked Transporter-2(SGLT-2) inhibitors and new types of mineralocorticoid receptor antagonists have emerged as effective ways to treat DKD. Moreover, researchers have proposed potential targeted therapies, such as inhibiting pro-inflammatory cytokines and modulating T cells and macrophages, among others. These therapies have demonstrated promising results in preclinical studies and clinical trials, suggesting their potential to treat DKD-induced tubulointerstitial lesions effectively. Understanding the immune-inflammatory mechanisms underlying DKD-induced tubulointerstitial lesions and developing targeted therapies could significantly improve the treatment and management of DKD. This review summarizes the latest advances in this field, highlighting the importance of focusing on tubulointerstitial inflammation mechanisms to improve DKD outcomes.

Lipocalin-2 as a biomarker for diabetic nephropathy

Diabetes is a major global public health issue. The prevalence of type 1 diabetes is comparatively static, as hereditary and genetic causes are involved, while type 2 diabetes (T2D) prevalence is increasing day by day. T2D is associated with chronic complications, including diabetic neuropathy (DN), nephropathy, retinopathy, and other complications like diabetic foot. DN is the main complication of both types of diabetes. DN can be diagnosed by routine laboratory tests, microalbuminuria > 300 mg/24 h, and a gradual decrease in glomerular filtration rate. As the appearance of microalbuminuria is a late manifestation, an early marker for renal damage is needed. Lipocalin-2, also known as neutrophil gelatinase-associated lipocalin (NGAL), is a small protein purified from neutrophil granules and a good marker for kidney disease. NGAL is a transporter protein responsible for many physiological processes, such as inflammation, generation of the immune response, and metabolic homeostasis. NGAL has been reported to depict the early changes in renal damage when urine microalbumin is still undetecable. Therefore, elucidating the role of NGAL in detecting DN and understanding its mechanism can help establish it as a potential early marker for DN.

Novel biomarkers for prognosticating diabetic kidney disease progression

The global burden of diabetic kidney disease (DKD) is escalating, and it remains as a predominant cause of the end-stage renal disease (ESRD). DKD is associated with increased cardiovascular disease and morbidity in all types of diabetes. Prediction of progression with albuminuria and eGFR is challenging in DKD, especially in non-proteinuric DKD patients. The pathogenesis of DKD is multifactorial characterized by injury to all components of the nephron, whereas albuminuria is an indicator of only glomerular injury. The limits in the diagnostic and prognostic value of urine albumin demonstrate the need for alternative and clinically significant early biomarkers, allowing more targeted and effective diabetic treatment, to reduce the burden of DKD and ESRD. Identification of biomarkers, based on multifactorial pathogenesis of DKD can be the crucial paradigm in the treatment algorithm of DKD patients. This review focuses on the potential biomarkers linked to DKD pathogenesis, particularly with the hope of broadening the diagnostic window to identify patients with different stages of DKD progression.

Novel Biomarkers of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a highly prevalent condition worldwide. It represents one of the most common complications arising from diabetes mellitus (DM) and is the leading cause of end-stage kidney disease (ESKD). Its development involves three fundamental components: the hemodynamic, metabolic, and inflammatory axes. Clinically, persistent albuminuria in association with a progressive decline in glomerular filtration rate (GFR) defines this disease. However, as these alterations are not specific to DKD, there is a need to discuss novel biomarkers arising from its pathogenesis which may aid in the diagnosis, follow-up, therapeutic response, and prognosis of the disease.

Correlation between urine vitamin Dbinding protein and earlystage renal damage in Type 2 diabetes

OBJECTIVES

The excretion of urinary vitamin D-binding protein (uVDBP) is related to the occurrence and development of early-stage renal damage in patients with Type 2 diabetes (T2DM). This study aims to explore the significance of detecting uVDBP in T2DM patients and its relationship with renal tubules, and to provide a new direction for the early diagnosis of T2DM renal damage.

METHODS

A total of 105 patients with T2DM, who met the inclusion criteria, were included as a patient group, and recruited 30 individuals as a normal control group. The general information and blood and urine biochemical indicators of all subjects were collected; the levels of uVDBP, and a marker of tubular injury [urine kidney injury molecule 1 (uKIM-1), urine neutrophil gelatinase-associated lipocalin (uNGAL) and urine retinol-binding protein (uRBP)] were detected by enzyme-linked immunosorbent assay. The results were corrected by urinary creatinine (Cr) to uVDBP/Cr, uKIM-1/Cr, uNGAL/Cr and uRBP/Cr. The Pearson's and Spearman's correlation tests were used to analyze the correlation between uVDBP/Cr and urine albumin-to-creatinine ratio (UACR), estimated glomerular filtration rate (eGFR) and markers of tubular injury, and multivariate linear regression and receiver operating characteristic curve were used to analyze the correlation between uVDBP/Cr and UACR or eGFR.

RESULTS

Compared with the normal control group, the uVDBP/Cr level in the patient group was increased (P<0.05), and which was positively correlated with UACR (r=0.774, P<0.01), and negatively correlated with eGFR (r=-0.397, P<0.01). There were differences in the levels of uKIM-1/Cr, uNGAL/Cr, and uRBP/Cr between the 2 groups (all P<0.01). The uVDBP/Cr was positively correlated with uKIM-1/Cr (r=0.752, P<0.01), uNGAL/Cr (r=0.644, P<0.01) and uRBP/Cr (r=0.812, P<0.01). The sensitivity was 90.0% and the specificity was 82.9% (UACR>30 mg/g) for evaluation of uVDBP/Cr on T2DM patients with early-stage renal damage, while the sensitivity was 75.0% and the specificity was 72.6% for evaluation of eGFR on T2DM patients with early-stage renal damage.

CONCLUSIONS

The uVDBP/Cr can be used as a biomarker in early-stage renal damage in T2DM patients.

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

Diabetic kidney disease is expected to increase rapidly over the coming decades with rising prevalence of diabetes worldwide. Current measures of kidney function based on albuminuria and estimated glomerular filtration rate do not accurately stratify and predict individuals at risk of declining kidney function in diabetes. As a result, recent attention has turned towards identifying and assessing the utility of biomarkers in diabetic kidney disease. This review explores the current literature on biomarkers of inflammation and kidney injury focussing on studies of single or multiple biomarkers between January 2014 and February 2020. Multiple serum and urine biomarkers of inflammation and kidney injury have demonstrated significant association with the development and progression of diabetic kidney disease. Of the inflammatory biomarkers, tumour necrosis factor receptor-1 and -2 were frequently studied and appear to hold most promise as markers of diabetic kidney disease. With regards to kidney injury biomarkers, studies have largely targeted markers of tubular injury of which kidney injury molecule-1, beta-2-microglobulin and neutrophil gelatinase-associated lipocalin emerged as potential candidates. Finally, the use of a small panel of selective biomarkers appears to perform just as well as a panel of multiple biomarkers for predicting kidney function decline.

Comparative diagnostic utility of different urinary biomarkers during pre-albuminuric stages of non-hypertensive type 2 diabetic nephropathy

Background & objectives

Activation of renin-angiotensin system and tubulointerstitial damage might be seen in pre-albuminuria stage of diabetic nephropathy (DN). Here, diagnostic utility of four urinary biomarkers [Angiotensinogen (Angio), Interleukin (IL)-18, Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Cystatin] during pre-albuminuria stages of non-hypertensive type 2 diabetes patients was studied.

Methods

A total of 952 type 2 diabetes mellitus (T2DM) patients were screened for nephropathy [estimated glomerular filtration rate (eGFR) ≥120 ml/min and albumin-creatinine ratio (ACR) ≥30], and 120 patients were followed up for one year. At one year, they were classified into hyperfiltration (43), normoalbuminuria (29) and microalbuminuria (48) groups. Another 63 T2DM patients without nephropathy were included as controls. Hypertension, patients on angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, eGFR <60 ml/min/1.73 m² and all proteinuric conditions were excluded. All were subjected to testing for urine protein, ACR, HbA₁C, eGFR, along with urinary biomarkers (IL-18, cystatin-C, NGAL and AGT). Comparative analysis of all the diagnostic tests among different subgroups, correlation and logistic regression was done.

Results

Urinary IL-18/Cr, cystatin/creatinine (Cr) and AGT/Cr levels were higher in groups of hyperfiltration (13.47, 12.11 and 8.43 mg/g), normoalbuminuria (9.24, 11.74 and 9.15 mg/g) and microalbuminuria (11.59, 14.48 and 10.24 mg/g) than controls (7.38, 8.39 and 1.26 mg/g), but NGAL/Cr was comparable. The area under receiver operating characteristic curve (AUC) and sensitivity of AGT to detect early CKD were higher than ACR and eGFR (0.91 and 90.4%, 0.6 and 40% and 0.6 and 37%, respectively). AUC values of other biomarkers, namely IL-18/Cr, cystatin/Cr and NGAL/Cr, were 0.65, 0.64 and 0.51, respectively. Angio/Cr and IL-18/Cr showed correlation with log albuminuria (r=0.3, P=0.00, and r=0.28, P=0.00, respectively). NGAL showed correlation with log eGFR (r=0.28 P=0.00). Multivariate logistic analysis showed that odds ratio of developing nephropathy was 7.5 times with higher values of log Angio/Cr.

Interpretation & conclusions

Urinary AGT showed a higher diagnostic value than ACR and eGFR followed by IL-18 and cystatin to diagnose DN during pre-albuminuric stages.

Urinary NGAL is a Potential Biomarker for Early Renal Injury in Insulin Resistant Obese Non-diabetic Children

OBJECTIVE

Neutrophil gelatinase-associated lipocalin (NGAL) is one of the new biomarkers for detecting acute renal injury. There are studies showing the relationship between NGAL and renal injury in obese children. The aim of this study was to investigate whether urinary levels of NGAL, kidney injury molecule-1, and serum cystatin C are increased in insulin resistance (IR) patients before the development of diabetes.

METHODS

Cross-sectional, case-controlled study that included non-diabetic obese children and adolescent patients with IR and a non-diabetic obese control group with no IR, who attended a tertiary center pediatric endocrinology outpatient clinic between 2016-2018. Those with diabetes mellitus and/or known renal disease were excluded. NGAL and creatinine (Cr) levels were evaluated in the morning spot urine from all participants. Serum renal function was evaluated.

RESULTS

Thirty-six control and 63 IR patients were included in the study, of whom 68 (68.7%) were girls. The mean age of all participants was 13.12±2.64 years and no statistically significant difference was found between the two groups in terms of age or gender distribution. Median (range) spot urinary NGAL (u-NGAL) values in the IR group were significantly higher at 26.35 (7.01-108.7) ng/mL than in the control group at 19.5 (3.45-88.14) ng/mL (p=0.018). NGAL/Cr ratio was also significantly higher in the IR group compared to the control group (p=0.018).

CONCLUSION

Obese pediatric patients with IR were shown to have elevated levels of u-NGAL, a marker of renal injury. u-NGAL examination may show early renal injury before development of diabetes.

Association between Neutrophil Gelatinase-Associated Lipocalin and Fetal Hemoglobin Levels in Patients with Type 2 Diabetes Mellitus

The effect of neutrophil gelatinase-associated lipocalin (NGAL) on fetal hemoglobin (HbF) levels in diabetic patients is rarely investigated. This study is aimed at investigating the possible association between NGAL and HbF levels in type 2 diabetes mellitus (T2DM). A total of 160 patients with T2DM and 61 healthy individuals were evaluated. NGAL, HbF, tumor necrosis factor-α (TNF-α), interleukin-5 (IL-5), glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), and urine albumin levels were measured. HbF levels were significantly higher in patients with elevated NGAL than in those without elevated NGAL (1.44% versus 0.94%, P = 0.001). High HbF was 2.3 times more prevalent in patients with elevated NGAL than in those without elevated NGAL. In addition, NGAL, TNF-α, and IL-5 levels were significantly higher in patients with high HbF than in those with low HbF; however, there was no significant difference in HbA1c and FPG levels between the two groups. HbF was positively correlated with NGAL (r = 0.275, P < 0.001), TNF-α (r = 0.256, P < 0.001), and IL-5 (r = 0.212, P < 0.001), but not with HbA1c and FPG. An elevated NGAL level led to a 1.27-fold increase in the prevalence of high HbF (odds ratio: 1.27, 95% CI: 1.03–2.51, and P < 0.001). The diagnostic efficacy of NGAL to identify an elevated HbF level was superior to that of HbA1c (area under the curve: 0.697, 95% CI: 0.609–0.786 versus 0.584, 95% CI: 0.488–0.681, and P = 0.022). In conclusion, enhanced NGAL production may be closely linked to elevated HbF in conjunction with proinflammatory cytokines in patients with T2DM.

Impact of Human Umbilical Cord Blood Mononuclear Cells on Gentamicin-Induced Renal Injury and Genotoxicity in Rats

Background: Acute kidney injury (AKI), also known as acute renal failure (ARF), has received considerable critical attention in recent years. Gentamicin (GM) is an antibiotic whose prolonged use results in AKI with a high mortality rate.

Methods: Fifty adult female albino rats weighing 150–200 g were used. The animals were divided into five groups: the first group was the normal healthy control one, the second group received only 1 × 10⁶ HUCB mononuclear cells (MNCs)/rat by intravenous (iv) injection, the third diseased group was given GM 100 mg/kg for 10 consecutive days by intraperitoneal injections, the fourth preventive group received 1 × 10⁶ HUCB MNCs/rat by iv injection 24 h before gentamicin treatment, and the fifth treated group received 1 × 10⁶ HUCB MNCs/rat by iv injection 24 h after gentamicin treatment. After 1 week of treatment, blood samples were collected, and kidneys were removed for histopathological examination.

Results: Rats treated with HUCB MNCs in the treated group had a significant decrease in renal damage, low levels of biomarkers for nephrotoxicities such as serum creatinine and blood urea nitrogen, and low chromosomal aberrations compared to the diseased third group. The gene expression of KIM-1 and NGAL was decreased in response to HUCB treatment.

Conclusions: HUCB MNCs have a curative effect against AKI and gentamicin-induced genotoxicity owing to their regenerative property.

Biomarkers of high salt intake

High salt intake is associated with hypertension, which is a leading modifiable risk factor for cardiovascular disease (CVD) and chronic kidney disease (CKD). International Guidelines recommend a large reduction in the consumption of sodium to reduce blood pressure, organ damage, and mortality. In its early stages, the symptoms of CKD are generally not apparent. CKD proceeds in a "silent" manner, necessitating the need for urinary biomarkers to detect kidney damage at an early stage. Since traditional renal biomarkers, such as serum creatinine, are not sufficiently sensitive, difficulties are associated with detecting kidney damage induced by a high salt intake, particularly in normotensive individuals. Several new biomarkers for renal tubular damage, such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), vanin-1, liver-type fatty acid-binding protein (L-FABP), and monocyte chemotactic protein-1 (MCP-1), have recently been identified. However, few studies have investigated early biomarkers for CKD progression associated with a high salt diet. This chapter provides insights into novel biomarkers for CKD in normo- and hypertensive individuals with a high salt intake. Recent studies using spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) fed a high salt diet identified urinary vanin-1 and NGAL as early biomarkers for renal tubular damage in SHR and WKY, whereas urinary KIM-1 was a useful biomarker for salt-induced renal injury in SHR only. Clinical studies are needed to confirm these findings.

Midkine: Utility as a Predictor of Early Diabetic Nephropathy in Children with Type 1 Diabetes Mellitus

Objective

This study aimed to assess the role of serum midkine (MK) as a biomarker for early detection of diabetic nephropathy in children with type 1 diabetes mellitus (T1DM) before microalbuminuria emerges.

Methods

A total of 120 children with T1DM, comprising 60 microalbuminuric patients (Group 1), 60 normoalbuminuric patients (Group 2), and 60 healthy participants as a control group (Group 3) were included. Detailed medical history, clinical examination, and laboratory assessment of high-sensitivity C-reactive protein (hs-CRP), hemoglobin A1c percentage (HbA1c%), lipid profile, urinary albumin to creatinine ratio (ACR), serum MK and estimated glomerular filtration rate based on serum creatinine were performed in all participants.

Results

Both Group 1 and Group 2 had significantly higher serum MK compared to controls (p<0.001). Additionally, significantly higher MK concentrations were present in Group 1 compared with Group 2 (p<0.001). Receiver operating characteristic curve analysis revealed that the MK concentration cutoff value of 1512 pg/mL was able to predict microalbuminuria with a sensitivity of 96% and specificity of 92%. Stepwise regression analysis revealed that HbA1c%, hs-CRP, and ACR were independently related to MK levels (p<0.001 for each).

Conclusion

The results of this study suggest that serum MK is a useful, novel, practical marker for the evaluation of renal involvement in children with T1DM, especially in normoalbuminuric children.

Knockout of NGAL aggravates tubulointerstitial injury in a mouse model of diabetic nephropathy by enhancing oxidative stress and fibrosis

Neutrophil gelatinase-associated lipocalin (NGAL), also called lipocalin 2, is considered a promising biomarker for acute and chronic kidney injuries. Several studies have demonstrated that its levels increase in plasma and urine in diabetic nephropathy (DN), and its urine concentration increases upon kidney function deterioration. However, its role in DN progression remains unclear. The current study used in vitro gene expression knockdown in human proximal tubular cell line human kidney (HK)2 to investigate the role of NGAL in oxidation and extracellular matrix secretion under high-glucose (HG) incubation. In addition, type 1 diabetes was induced in vivo in knockout NGAL^-/- and wild-type mice in order to investigate role of NGAL in the progression of DN. The results demonstrated that NGAL knockdown in HK2 cells significantly increased oxidative stress under HG stimulation tested by flow cytometry, and increased the secretion of interleukin-6, fibronectin (FN) and collagen IV examined by ELISA. Western blotting demonstrated that the phosphorylation of Smad2/3 also increased in HK2 cells under transforming growth factor-β1 stimulation. In vivo experiments demonstrated that diabetic NGAL^-/- mice showed deteriorated renal function compared with that of diabetic wild-type mice. Histopathological analysis suggests that diabetic NGAL^-/- mice had more serious glomerulosclerosis and tubular vascular degeneration than wild-type mice. Immunohistochemistry suggested that the absence of NGAL lead to increased FN deposition in glomeruli in a mouse model of DN. In conclusion, NGAL appears to have renal protective effects by slowing down the progression of DN, and its effect may be associated with a reduction in oxidation, fibrosis and inflammation.

Current updates on protein as biomarkers for diabetic kidney disease: a systematic review

BACKGROUND

In the past decade, researchers have been focused on discovering protein biomarkers for diabetic kidney disease. This paper aims to search for, analyze, and synthesize current updates regarding the development of these efforts.

METHODS

We systematically searched the ScienceDirect, SpringerLink, and PubMed databases for observational studies of protein biomarkers in patients with diabetes mellitus. We included studies published between January 2018 and April 2020, that were based on a population of patients with type-1 or type-2 diabetes mellitus aged ⩾18 years, with an observational design such as cross-sectional, case-control, or cohort studies. The dependent variable of the research results was in the form of protein biomarkers from urine, plasma, or serum.

RESULTS

Following the screening process, 20 research articles with available full text met the inclusion criteria. These could be categorized as glomerular biomarkers (ANGPTL4, beta-2 microglobulin, Smad1, and glypican-5); inflammatory biomarkers (MCP-1 and adiponectin); and tubular biomarkers (NGAL, VDBP, megalin, sKlotho, and KIM-1). The development of a panel of biomarkers showed more promising results than those for a single biomarker in diagnosing diabetic kidney disease.

CONCLUSION

All the biomarkers discussed in this review showed promising results for predicting diabetic kidney disease because they correlate with albuminuria, eGFR, or both. However, of the 11 protein biomarkers, none have prognostic value beyond albuminuria and eGFR.

Urinary proteins detected using modern proteomics intervene in early type 2 diabetic kidney disease – a pilot study

Aim: An advanced proteomics platform for protein biomarker discovery in diabetic chronic kidney disease (DKD) was developed, validated and implemented. Materials & methods: Three Type 2 diabetes mellitus patients and three control subjects were enrolled. Urinary peptides were extracted, samples were analyzed on a hybrid LTQ-Orbitrap Velos Pro instrument. Raw data were searched using the SEQUEST algorithm and integrated into Proteome Discoverer platform. Results & discussion: Unique peptide sequences, resulted sequence coverage, scoring of peptide spectrum matches were reported to albuminuria and databases. Five proteins that can be associated with early DKD were found: apolipoprotein AI, neutrophil gelatinase-associated lipocalin, cytidine deaminase, S100-A8 and hemoglobin subunit delta. Conclusion: Urinary proteome analysis could be used to evaluate mechanisms of pathogenesis of DKD.

Evaluation of early biomarkers of renal dysfunction in diabetic patients

Objectives:

To evaluate 2 renal tubular enzymes; urinary neutrophil gelatinase-associated lipocalin (uNGAL), and urinary N-acetyl-beta-D-glucosaminidase (uNAG), and serum Cystatin C as candidate biomarkers for early diagnosis of early stage of diabetic nephropathy (DB) in patients with type 2 diabetes mellitus (T2DM).

Methods:

This cross-sectional study was carried out at King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia during the period between May 2017 and May 2018 and was conducted on 86 patients with T2DM. Patients were classified according to their albumin/creatinine ratio (ACR) into 3 groups; a normal albuminuria group with ACR <30 mg/g creatinine, a moderately increased albuminuria group with ACR: 30-299 mg/g creatinine, and a severely increased albuminuria group with ACR ≥300 mg/g. Healthy adults were recruited as a control group. Urine uNGAL, uNAG, and serum Cystatin C were measured in all patients.

Results:

Compared with healthy control, diabetic patients with normal albuminuria excreted significantly higher levels of uNGAL (p<0.001). In addition, significantly elevated uNGAL, uNAG and cystatin C levels were observed in moderately increased albuminuria and severely increased albuminuria groups when compared to the control and normoalbuminuric groups (p<0.001). urinary neutrophil gelatinase-associated lipocalin, urinary N-acetyl-beta-D-glucosaminidase and Cystatin C showed a positive correlation with fasting blood glucose (FBG), HbA1c, duration of diabetes, urea, creatinine, and ACR.

Conclusion:

Our results indicated that uNGAL could be a sensitive biomarker for early renal dysfunction in diabetic patients while uNAG and serum Cystatin C might have prognostic value.

Assessment of urinary NGAL for differential diagnosis and progression of diabetic kidney disease

OBJECTIVE

Chronic kidney disease (CKD) related to diabetes has become more common than glomerulonephritis in recent years. Given the inefficient and difficult identification of diabetic kidney disease (DKD) from non-diabetic kidney disease (NDKD) as well as a result of emerging evidence supporting a role for tubular involvement in DKD, we aimed to investigate the utility of urinary neutrophil gelatinase-associated lipocalin (uNGAL) in the differential diagnosis and predictive value of DKD from NDKD.

METHODS

Data for 100 type 2 diabetic patients with CKD at our center from June 2016 to August 2019 were reviewed. All the patients were categorized into 2 groups by the renal biopsy results: DKD and NDKD. Urinary NGAL levels were normalized by urinary creatinine and calculated as uNGAL/creatinine ratios (uNCR). The independent factors of the occurrence of DKD and the diagnostic implications of uNCR were explored by logistic regression and receiver-operating characteristic (ROC) curve analysis. In addition, we analyzed the relationship between uNCR and proteinuria in patients with DKD by Pearson test and linear regression. Kaplan-Meier survival analysis was performed to assess the prospective association of uNCR with the renal outcome.

RESULTS

Significantly higher levels of uNCR were observed in patients with DKD when compared to those with NDKD (28.65 ng/mg vs 27.47 ng/mg, p< .001). uNCR was identified as an independent risk factor for the occurrence of DKD in diabetic patients with CKD (odds ratio [OR] = 1.020; 95%CI = [1.001-1.399], p = .042). The optimal cutoff value of uNCR for predicting DKD was 60.685 ng/mg with high specificity (90.5%) but relatively low sensitivity (55.7%). In Pearson test, uNCR was positively correlated with proteinuria, serum creatine, blood urea nitrogen, duration of diabetes, interstitial inflammation score and global sclerosis, whereas it was inversely correlated with eGFR, hemoglobin, serum albumin and 25-hydroxy vitamin D. Furthermore, in a fully adjusted model including eGFR, serum albumin and total cholesterol, the group with uNCR>60.685 ng/mg was associated with 7.595 times higher likelihood of nephrotic-range proteinuria compared to the group with uNCR≤60.685 ng/mg. In the Kaplan-Meier survival analysis, the event-free survival probability in patients with uNCR>60.685 ng/mg was significantly lower than those with uNCR≤60.685 ng/mg (p = .048).

CONCLUSIONS

uNCR might serve as a potential tool for identifying cases in which there was a high clinical suspicion of DKD and that in whom confirmatory biopsy could be considered, and the best predictive cutoff value of normalized uNCR for DKD diagnosis was 60.685 ng/mg. Type 2 diabetic patients with increased level of uNCR had higher risk to nephrotic-range proteinuria and worse renal outcome.

Prediction Value of Serum NGAL in the Diagnosis and Prognosis of Experimental Acute and Chronic Kidney Injuries

Sensitive and accurate serum biomarkers for monitoring acute and chronic kidney disease progression are more convenient and can better evaluate drug efficiency in pharmacological research. Neutrophil Gelatinase-associated Lipocalin (NGAL) is considered a hopeful early biomarker of acute kidney injury (AKI), but its utility in early prediction and prognosis of diabetic nephropathy (DN) and immune-mediated glomerulonephritis is still not clear. Moreover, detailed prognosis studies of NGAL in AKI are lacking, and most studies use a urine source. In the current study, through two experimental AKI and two chronic kidney injury animal models, serum NGAL (sNGAL) prediction values on diagnosis and prognosis of kidney injuries in animal disease models have been investigated thoroughly. Four experimental kidney disease models include cisplatin-induced and lipopolysaccharide (LPS)-induced AKI, streptozocin-induced diabetic nephropathy (DN), and cationized-bovine serum albumin (c-BSA)-induced membranous nephropathy (MN), respectively. The sNGAL concentration was measured at different stages of kidney injury (KI) in each experimental model, and receiver operating characteristic (ROC) analyses were performed to investigate the diagnosis efficiency of sNGAL for KI. Western blot and immunohistochemistry were used to measure the protein levels in the kidneys, and pathological analysis was used as the gold standard to confirm KI. Results suggest that sNGAL can predict early diagnosis of cisplatin-induced AKI accurately but is less powerful in later stages compared to blood urea nitrogen (BUN) and serum creatinine (Scr). sNGAL is sensitive but lacks specificity to evaluate early kidney injury for LPS-induced AKI under low-dosage LPS challenge. sNGAL is not an efficient biomarker for early diagnosis of STZ-induced DN, but sNGAL is an efficient predictor for the early diagnosis and prognosis of immune-mediated MN. In conclusion, application of sNGAL as a kidney injury biomarker to determine the diagnosis and prognosis in pharmacological studies is dependent on experimental animal models.

Neutrophil Gelatinase-Associated Lipocalin and Retinol-Binding Protein-4 as Biomarkers for Diabetic Kidney Disease

AIMS

This study was designed to evaluate the conflicting association between 2 tubular protein markers including neutrophil gelatinase-associated lipocalin (NGAL) and retinol-binding protein-4 (RBP-4) with albuminuria and glomerular filtration rate (GFR) and calculate the accuracy of the role of NGAL and RBP-4 in diagnosis of diabetic nephropathy (DN) in patients with type2 diabetes.

METHODS

This is a cross-sectional study that included 133 patients with type 2 diabetes. There were 3 diabetic study groups with normoalbuminuria, moderately increased albuminuria, severely increased albuminuria, and non-diabetic control group without any renal disease. We analyzed the difference of urinary NGAL (uNGAL) and RBP-4 between nondiabetics and diabetics, as well as within the diabetic group. We also assessed the association between albuminuria and NGAL and RBP-4.

RESULTS

The urinary levels of NGAL and RBP-4 were higher in patients with type 2 diabetes compared to nondiabetics as well as in albuminuric diabetics compared to nonalbuminuric patients with diabetes (p value <0.001). These 2 proteins were higher in patients with severely increased albuminuria compared to patients with moderately increased albuminuria, even after adjustment for other metabolic factors (all p < 0.01). Moreover, areas under the curve of NGAL and RBP-4 for the diagnosis of chronic kidney disease were 80.6 and 74.6%, respectively.

CONCLUSION

uNGAL and RBP-4 are potential markers of tubular damage that may increase before the onset of glomerular markers such as albuminuria and GFR in patients with type 2 diabetes. Therefore, these markers can be used as complementary measurements to albuminuria and GFR in the earlier diagnosis of DN.

Urine NGAL as an early biomarker for diabetic kidney disease: accumulated evidence from observational studies

Objectives: Urine neutrophil gelatinase-associated lipocalin (NGAL) was found to increase in diabetic kidney disease (DKD). However, the clinical value of urine NGAL as diagnostic indicators in DKD remains to be clarified. Methods: Relevant studies were systematically retrieved from PubMed, Embase, Web of Science, and the Cochrane Library. Stratified analyses and regression analyses were performed. Results: Fourteen studies with 1561 individuals were included in our analysis, including 1204 cross-sectional participants and 357 cohort participants. For the cross-sectional studies, the pooled sensitivity and specificity of NGAL in the diagnosis of DKD were 0.82 (95% confidence interval (CI): 0.75-0.87) and 0.81 (95% CI: 0.68-0.90), respectively. The pooled diagnostic odds ratio was 19 (95% CI: 11-33), and the overall area under the curve was 0.88 (95% CI: 0.84-0.90). For the cohort studies, the pooled sensitivity and specificity of NGAL in the diagnosis of DKD were 0.96 (95% CI: 0.91-0.98) and 0.89 (95% CI: 0.84-0.92), respectively. The overall area under the curve was 0.98, indicating good discriminative ability of NGAL as biomarkers for DKD. Conclusions: Urine NGAL, as the early diagnostic marker of DKD, might have the high diagnostic value, especially in cohort studies.

Diagnostic value of neutrophil gelatinase-associated lipocalin in diabetic nephropathy: a meta-analysis

Purpose: This meta-analysis aimed to determine the diagnostic performance of neutrophil gelatinase-associated lipocalin (NGAL) in diabetic nephropathy (DN). Methods: We searched the PubMed, Embase, Wanfang, and China National Knowledge Infrastructure databases for articles published up to 24 April 2019. The meta-analyses were conducted by Stata 11.0, and diagnostic accuracy, sensitivity, specificity, negative and positive likelihood ratios (NLR and PLR), diagnostic odds ratio (DOR), and receiver operating characteristic (ROC) curve data were pooled. Moreover, heterogeneity and small trials bias were evaluated. Results: Six cross-sectional studies were included in the meta-analysis. For the studies of microalbuminuria versus normoalbuminuria, the estimates (95% confidence interval) were as follows: sensitivity, 0.75 (0.51-0.89); specificity, 0.78 (0.70-0.84); PLR, 3.37 (2.49-4.56); NLR, 0.33 (0.16-0.69); DOR, 10.31 (4.05-26.25); and area under the ROC curve (AUC), 0.81 (0.77-0.84). For the studies of microalbuminuria + macroalbuminuria versus normoalbuminuria, the results were as follows: sensitivity, 0.83 (0.66-0.93); specificity, 0.88 (0.67-0.97); PLR, 7.20 (1.97-26.31); NLR, 0.19 (0.08-0.46); DOR, 37.83 (4.84-295.65); AUC, 0.92 (0.90-0.94). Deeks' funnel plot suggested that small trials bias was insignificant in this study. Conclusions: Our findings suggest that NGAL is a potential diagnostic marker for patients with DN and that its diagnostic value for microalbuminuria + macroalbuminuria is superior to that for microalbuminuria. Highlights The first meta-analysis to investigate NGAL diagnostic role in DN. NGAL is valuable for the early diagnosis of DN. The diagnostic value of NGAL in microalbuminuria + macroalbuminuria was much higher.

Optimising streptozotocin dosing to minimise renal toxicity and impairment of stomach emptying in male 129/Sv mice

The streptozotocin (STZ)-induced diabetic mouse model has been extensively used as a model for diabetes and diabetic nephropathy, but it is still influenced by many off-target toxic effects and large variation in diabetes induction. Therefore, the aim of this study was to compare different STZ dosing regimens to optimise animal welfare and minimise unwanted effects of STZ measured by acute renal toxicity, impairment of stomach emptying and weight loss. Male 129/Sv mice were injected with 1 × 50, 1 × 100, 1 × 125, 1 × 150, 1 × 200, 5 × 50, 2 × 100 and 2 × 125 mg/kg STZ or vehicle and euthanized 24 hours after the last injection. All STZ doses were found to induce significant enlargement of the stomach. All multiple doses of STZ increased the albumin:creatinine ratio significantly, and immunohistochemical staining of KIM-1 and Ki-67 was increased by 5 × 50 and 2 × 100 mg/kg STZ. Renal gene expression of Cdkn1a, KIM-1, NGAL and MCP-1 was increased by most of the STZ doses. No difference was found between the double intermediate dose of 2 × 100 mg/kg and the multiple low dose of 5 × 50 mg/kg regarding either stomach enlargement or kidney injury. However, the reduced fasting periods and injections in the 2 × 100 mg/kg STZ group could have lowered the impact on the general condition measured as change in body weight. This shows that the double intermediate dose is a good alternative to the recommended multiple low dose for diabetes induction in these mice. The STZ-induced mouse model has again proven to be a model with large variations affecting both animal welfare and model robustness.

Urinary biomarkers of tubular injury to predict renal progression and end stage renal disease in type 2 diabetes mellitus with advanced nephropathy: A prospective cohort study

BACKGROUND

Novel potential tubular biomarkers in diabetic nephropathy could improve risk stratification and prediction. The study aimed to evaluate the association of tubular damage markers with rapid renal progression and incidence of end stage renal disease (ESRD) in type 2 diabetes (T2DM).

METHODS

A prospective cohort study, involving a total of 257 patients with T2DM, was included. The baseline values of urine albumin, cystatin-C, angiotensinogen, kidney injury molecule-1 (KIM-1) and neutrophil-gelatinase associated lipocalin (NGAL) were measured. The composite outcomes included a rapid glomerular filtration rate (GFR) decline or incident of ESRD at 3-year follow-up.

MAIN FINDINGS

The composite outcomes were noted in 26.1%. Using univariate followed by multivariate COX proportional hazard regression analysis, the patients with highest quartiles of urine cystatin-C (HR 2.96, 95% CI, 1.38-6.35), urine angiotensinogen (HR 2.93, 95% CI, 1.40- 6.13) urine KIM-1 (HR 2.77, 95% CI, 1.27-6.05) and urine NGAL (HR 2.53, 95% CI, 1.11-5.76) were significantly associated with rapid renal progression when compared with the patients with the lowest quartiles of all tubular biomarkers.

CONCLUSIONS

Patients with T2DM with high levels of baseline urine tubular biomarkers (cystatin-C, angiotensinogen, KIM-1 and NGAL) had a greater incidence of ESRD and rapid GFR decline.

Diagnostic Accuracy of Neutrophil Gelatinase-Associated Lipocalin for Predicting Early Diabetic Nephropathy in Patients with Type 1 and Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis

BACKGROUND

Currently, there is a lack of prediction markers for diabetic nephropathy (DN) in patients with type 1 and type 2 diabetes mellitus (T1DM/T2DM). The aim of this systematic review and meta-analysis was to evaluate the value of a promising biomarker, neutrophil gelatinase-associated lipocalin (NGAL), in both serum and urine for the diagnosis of early DN in T1DM and T2DM patients with different stages of albuminuria.

METHODS

A comprehensive search was performed on PubMed by 2 reviewers until September 2018. Studies in which (a) the degree of DN was determined according to the urinary albumin/creatinine ratio and (b) NGAL was measured in healthy individuals and in diabetes patients with DN were included in the meta-analysis. For each study, a 2 × 2 contingency table was formulated. Sensitivity, specificity, and other estimates of accuracy were calculated using a bivariate random effects model. The hierarchical summary ROC method was used to pool data and to evaluate the area under the curve (AUC). The sources of heterogeneity were explored by subgroup analysis. Publication bias was assessed using the Deeks test.

RESULTS

The meta-analysis enrolled 22 studies involving 683 healthy individuals and 3249 patients with diabetes, of which 488 were T1DM and 2761 were T2DM patients. Overall, pooled sensitivity and specificity among the different settings analyzed ranged from 0.42 (95% CI, 0.22-0.66) to 1.00 (95% CI, 0.99-1.00) and 0.72 (95% CI, 0.62-0.80) to 0.98 (95% CI, 0.50-1.00) in T2DM patients, respectively. For T1DM patients, the corresponding estimates were 0.71 (95% CI, 0.59-0.81) to 0.89 (95% CI, 0.64-0.97) and 0.72 (95% CI, 0.62-0.80) to 0.79 (95% CI, 0.67-0.87). The AUC of NGAL for T2DM patients ranged from 0.69 (95% CI, 0.65-0.73) to 1.00 (95% CI, 0.99-1.00) in the different settings.

CONCLUSION

The results of this meta-analysis suggest that NGAL in both serum and urine can be considered a valuable biomarker for early detection of DN in diabetes patients.

Protective Effect of Salidroside Against Diabetic Kidney Disease Through Inhibiting BIM-Mediated Apoptosis of Proximal Renal Tubular Cells in Rats

Background: Accumulating evidences indicate that the apoptosis of proximal tubular epithelial cells (PTECs) play a vital role in the progression of the diabetic kidney disease (DKD). This study aimed to explore the therapeutic potential of salidroside (SAL) in DKD and its underlying mechanism in anti-apoptosis of PTECs. Methods: Twenty-eight male Wistar rats were allocated into four groups: sham-operated, uninephrectomy (unx), diabetes with uninephrectomy (DKD) and DKD treated with SAL (DKD + SAL). SAL (70 mg/kg) was gavage administered for 8 weeks. 24-h albuminuria and serum creatinine (SCr), blood urea nitrogen (BUN), renal histological changes were examined. The silico analysis was used to identify the main therapeutic targets and pathways of SAL involved in DKD treatment. Apoptosis was determined by TUNEL and Annexin V-FITC/PI double staining in vivo and in vitro, respectively. The expression of BIM, BAX, and cleaved caspase-3 were evaluated by western blot and immunostaining. Results: Treatment with SAL significantly attenuated diabetic kidney injury via inhibiting 24-h albuminuria, SCr, BUN, glomerular mesangial dilatation and tubular injury in DKD rats. The silico analysis identified the intrinsic apoptotic pathway as an important pathway responsible for the nephroprotective properties of SAL. Our data validated that SAL effectively inhibited the apoptosis of PTECs induced by high-glucose (HG), both in vitro and in vivo. Silence of BIM by shRNA in HK-2 cells prevented HG-induced apoptosis. The up-regulated BIM and its downstream targets (BAX and cleaved caspase-3) were also inhibited by SAL. Conclusion: In summary, SAL significantly relieved DKD. And the possible mechanisms might be partially attributed to inhibiting apoptosis of proximal renal tubular cells. The apoptotic protein BIM could be an important target of SAL in this process.