Possible relationship of monocyte chemoattractant protein-1 with diabetic nephropathy

Urinary biomarkers in diabetic nephropathy

Diabetic nephropathy (DN), a significant consequence of diabetes, is associated with adverse cardiovascular and renal disease as well as mortality. Although microalbuminuria is considered the best non-invasive marker for DN, better predictive markers are needed of sufficient sensitivity and specificity to detect disease in general and in early disease specifically. Even prior to appearance of microalbuminuria, urinary biomarkers increase in diabetics and can serve as accurate nephropathy biomarkers even in normoalbuminuria. In this review, a number of novel urine biomarkers including those reflecting kidney damage caused by glomerular/podocyte damage, tubular damage, oxidative stress, inflammation, and intrarenal renin-angiotensin system activation are discussed. Our review also includes emerging biomarkers such as urinary microRNAs. These short noncoding miRNAs regulate gene expression and could be utilized to identify potential novel biomarkers in DN development and progression. .

Unveiling Selected Influences on Chronic Kidney Disease Development and Progression

Currently, more and more people are suffering from chronic kidney disease (CKD). It is estimated that CKD affects over 10% of the population worldwide. This is a significant issue, as the kidneys largely contribute to maintaining homeostasis by, among other things, regulating blood pressure, the pH of blood, and the water-electrolyte balance and by eliminating unnecessary metabolic waste products from blood. What is more, this disease does not show any specific symptoms at the beginning. The development of CKD is predisposed by certain conditions, such as diabetes mellitus or hypertension. However, these disorders are not the only factors promoting the onset and progression of CKD. The primary purpose of this review is to examine renin-angiotensin-aldosterone system (RAAS) activity, transforming growth factor-β1 (TGF-β1), vascular calcification (VC), uremic toxins, and hypertension in the context of their impact on the occurrence and the course of CKD. We firmly believe that a deeper comprehension of the cellular and molecular mechanisms underlying CKD can lead to an enhanced understanding of the disease. In the future, this may result in the development of medications targeting specific mechanisms involved in the decline of kidney function. Our paper unveils the selected processes responsible for the deterioration of renal filtration abilities.

HMGN1 down-regulation in the diabetic kidney attenuates tubular cells injury and protects against renal inflammation via suppressing MCP-1 and KIM-1 expression through TLR4

BACKGROUND

Renal tubular injury, accompanied by damaging inflammation, has been identified to drive diabetic kidney disease (DKD) toward end-stage renal disease. However, it is unclear how damage-associated molecular patterns (DAMPs) activate innate immunity to mediate tubular epithelial cell (TEC) injury, which in turn causes with subsequent sterile inflammation in diabetic kidneys. High mobility group nucleosome-binding protein 1 (HMGN1) is a novel DAMP that contributes to generating the innate immune response. In this study, we focused on determining whether HMGN1 is involved in DKD progression.

METHODS

Streptozotocin (STZ)-induced diabetic mice model was established. Then we downrergulated HMGN1 expression in kidney with or without HMGN1 administration. The renal dysfunction and morphological lesions in the kidneys were evaluated. The expressions of KIM-1, MCP-1, F4/80, CD68, and HMGN1/TLR4 signaling were examined in the renal tissue. In vitro, HK2 cells were exposed in the high glucose with or without HMGN1, and further pre-incubated with TAK242 was applied to elucidate the underlying mechanism.

RESULTS

We demonstrated that HMGN1 was upregulated in the tubular epithelial cells of streptozotocin (STZ)-induced type 1 and type 2 diabetic mouse kidneys compared to controls, while being positively correlated with increased TLR4, KIM-1, and MCP-1. Down-regulation of renal HMGN1 attenuated diabetic kidney injury, decreased the TLR4, KIM-1, and MCP-1 expression levels, and reduced interstitial infiltrating macrophages. However, these phenotypes were reversed after administration of HMGN1. In HK-2 cells, HMGN1 promoted the expression of KIM-1 and MCP-1 via regulating MyD88/NF-κB pathway; inhibition of TLR4 effectively diminished the in vitro response to HMGN1.

CONCLUSIONS

Our study provides novel insight into HMGN1 signaling mechanisms that contribute to tubular sterile injury and low-grade inflammation in DKD. The study findings may help to develop new HMGN1-targeted approaches as therapy for immune-mediated kidney damage rather than as an anti-infection treatments.

Monocyte Chemoattractant Protein-1 (MCP-1), Activin-A and Clusterin in Children and Adolescents with Obesity or Type-1 Diabetes Mellitus

Inflammation plays a crucial role in diabetes and obesity through macrophage activation. Macrophage chemoattractant protein-1 (MCP-1), activin-A, and clusterin are chemokines with known roles in diabetes and obesity. The aim of this study is to investigate their possible diagnostic and/or early prognostic values in children and adolescents with obesity and type-1 diabetes mellitus (T1DM).

METHODS

We obtained serum samples from children and adolescents with a history of T1DM or obesity, in order to measure and compare MCP-1, activin-A, and clusterin concentrations.

RESULTS

Forty-three subjects were included in each of the three groups (controls, T1DM, and obesity). MCP-1 values were positively correlated to BMI z-score. Activin-A was increased in children with obesity compared to the control group. A trend for higher values was detected in children with T1DM. MCP-1 and activin-A levels were positively correlated. Clusterin levels showed a trend towards lower values in children with T1DM or obesity compared to the control group and were negatively correlated to renal function.

CONCLUSIONS

The inflammation markers MCP-1, activin-A, and clusterin are not altered in children with T1DM. Conversely, obesity in children is positively correlated to serum MCP-1 values and characterized by higher activin-A levels, which may reflect an already established systematic inflammation with obesity since childhood.

Role of novel biomarker monocyte chemo-attractant protein-1 in early diagnosis & predicting progression of diabetic kidney disease: A comprehensive review

Diabetic kidney disease (DKD) is the most devastating complication of diabetes mellitus. Identification of patients at the early stages of progression may reduce the disease burden. The limitation of conventional markers such as serum creatinine and proteinuria intensify the need for novel biomarkers. The traditional paradigm of DKD pathogenesis has expanded to the activation of the immune system and inflammatory pathways. Monocyte chemo-attractant protein-1 (MCP-1) is extensively studied, as a key inflammatory mediator that modulates the development of DKD. Recent evidence supports the diagnostic role of MCP-1 in patients with or without proteinuria in DKD, as well as a significant role in the early prediction and risk stratification of DKD. In this review, we will summarize and update present evidence for MCP-1 for diagnostic ability and predicting the progression of DKD.

Evaluation of Effect of Montelukast in the Model of Streptozotocin Induced Diabetic Nephropathy in Rats

Background

Diabetic nephropathy is a progressive condition and a leading cause of end-stage renal disease. Oxidative stress and inflammation play an important role in its pathogenesis. In pre-clinical studies, Montelukast had shown renoprotective and anti-oxidant properties, hence the study was planned to evaluate the effect of Montelukast in a Streptozotocin (STZ) induced model of diabetic nephropathy.

Methods

40 Wistar rats of either sex were randomly divided into four groups viz. 1. Vehicle control group, 2. Enalapril (5 mg/kg), 3. Montelukast low-dose (10 mg/kg) and 4. High-dose (20 mg/kg) group. On day 1, diabetes was induced using a single dose of STZ (60 mg/kg) intraperitoneally. Diabetes induction was verified based on fasting blood glucose (FBG) levels on day 7 and from day 8 to day 42, rats were given study drugs. FBG, serum creatinine, blood urea nitrogen (BUN) and urine microalbumin levels were assessed pre-study and post-study. Assessments of kidney malondialdehyde (MDA), reduced glutathione (GSH) and renal histopathology were carried out at the end of the study.

Results

Montelukast 10 mg/kg group showed significantly lower urine microalbumin levels compared to the vehicle control group (p < 0.05). Montelukast 20 mg/kg group showed significantly lower levels of FBG, serum creatinine, BUN and urine microalbumin compared to the vehicle control group (p < 0.05). In addition, Montelukast 20 mg/kg group also showed better effects on kidney MDA and GSH levels (p < 0.05) and histopathological scores compared to the vehicle control group.

Conclusion

Montelukast showed a protective effect in the model of diabetic nephropathy because of its antioxidant effect.

Associations of Biomarkers of Kidney Tubule Health, Injury, and Inflammation with Left Ventricular Hypertrophy in Children with CKD

Key Points

Higher plasma and urine kidney injury molecule-1, urine monocyte chemoattractant protein-1, and lower urine alpha-1-microglobulin were associated with left ventricular hypertrophy, even after adjustment for confounders. Biomarkers of tubular injury, dysfunction, and inflammation may indicate the severity of kidney pathology and are associated with left ventricular hypertrophy.

Background

Left ventricular hypertrophy (LVH) is common in children with CKD and is associated with an increased risk of cardiovascular disease and mortality. We have shown that several plasma and urine biomarkers are associated with increased risk of CKD progression. As CKD is associated with LVH, we sought to investigate the association between the biomarkers and LVH.

Methods

In the CKD in Children Cohort Study, children aged 6 months to 16 years with an eGFR of 30–90 ml/min per 1.73 m2 were enrolled at 54 centers in the United States and Canada. We measured plasma biomarkers kidney injury molecule-1 (KIM-1), tumor necrosis factor receptor-1, tumor necrosis factor receptor-2, soluble urokinase-type plasminogen activator receptor and urine KIM-1, monocyte chemoattractant protein-1 (MCP-1), YKL-40, alpha-1-microglobulin (alpha-1m), and epidermal growth factor in stored plasma and urine collected 5 months after enrollment. Echocardiograms were performed 1 year after enrollment. We assessed the cross-sectional association between the log2 biomarker levels and LVH (left ventricular mass index greater than or equal to the 95th percentile) using a Poisson regression model, adjusted for age, sex, race, body mass index, hypertension, glomerular diagnosis, urine protein-to-creatinine ratio, and eGFR at study entry.

Results

Among the 504 children, LVH prevalence was 12% (n =59) 1 year after enrollment. In a multivariable-adjusted model, higher plasma and urine KIM-1 and urine MCP-1 concentrations were associated with a higher prevalence of LVH (plasma KIM-1 prevalence ratio [PR] per log2: 1.27, 95% confidence interval [CI], 1.02 to 1.58; urine KIM-1 PR: 1.21, 95% CI, 1.11 to 1.48; and urine MCP-1 PR: 1.18, 95% CI, 1.04 to 1.34). After multivariable adjustment for covariates, lower urine alpha-1m was also associated with a higher prevalence of LVH (PR: 0.90, 95% CI, 0.82 to 0.99).

Conclusions

Higher plasma and urine KIM-1, urine MCP-1, and lower urine alpha-1m were each associated with LVH prevalence in children with CKD. These biomarkers may better inform risk and help elucidate the pathophysiology of LVH in pediatric CKD.

The role of monocytes in thrombotic diseases: a review

Cardiovascular and cerebrovascular diseases are the number one killer threatening people's life and health, among which cardiovascular thrombotic events are the most common. As the cause of particularly serious cardiovascular events, thrombosis can trigger fatal crises such as acute coronary syndrome (myocardial infarction and unstable angina), cerebral infarction and so on. Circulating monocytes are an important part of innate immunity. Their main physiological functions are phagocytosis, removal of injured and senescent cells and their debris, and development into macrophages and dendritic cells. At the same time, they also participate in the pathophysiological processes of pro-coagulation and anticoagulation. According to recent studies, monocytes have been found to play a significant role in thrombosis and thrombotic diseases of the immune system. In this manuscript, we review the relationship between monocyte subsets and cardiovascular thrombotic events and analyze the role of monocytes in arterial thrombosis and their involvement in intravenous thrombolysis. Finally, we summarize the mechanism and therapeutic regimen of monocyte and thrombosis in hypertension, antiphospholipid syndrome, atherosclerosis, rheumatic heart disease, lower extremity deep venous thrombosis, and diabetic nephropathy.

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.

SGLT2 Inhibitor—Dapagliflozin Attenuates Diabetes-Induced Renal Injury by Regulating Inflammation through a CYP4A/20-HETE Signaling Mechanism

Diabetic kidney disease (DKD) is a serious complication of diabetes, affecting millions of people worldwide. Inflammation and oxidative stress are key contributors to the development and progression of DKD, making them potential targets for therapeutic interventions. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have emerged as a promising class of drugs, with evidence demonstrating that they can improve renal outcomes in people with diabetes. However, the exact mechanism by which SGLT2i exert their renoprotective effects is not yet fully understood. This study demonstrates that dapagliflozin treatment attenuates renal injury observed in type 2 diabetic mice. This is evidenced by the reduction in renal hypertrophy and proteinuria. Furthermore, dapagliflozin decreases tubulointerstitial fibrosis and glomerulosclerosis by mitigating the generation of reactive oxygen species and inflammation, which are activated through the production of CYP4A-induced 20-HETE. Our findings provide insights onto a novel mechanistic pathway by which SGLT2i exerts their renoprotective effects. Overall, and to our knowledge, the study provides critical insights into the pathophysiology of DKD and represents an important step towards improving outcomes for people with this devastating condition.

Depiction of immune heterogeneity of peripheral blood from patients with type II diabetic nephropathy based on mass cytometry

Diabetic nephropathy (DN) is the most prominent cause of chronic kidney disease and end-stage renal failure. However, the pathophysiology of DN, especially the risk factors for early onset remains elusive. Increasing evidence has revealed the role of the innate immune system in developing DN, but relatively little is known about early immunological change that proceeds from overt DN. Herein, this work aims to investigate the immune-driven pathogenesis of DN using mass cytometry (CyTOF). The peripheral blood mononuclear lymphocytes (PBMC) from 6 patients with early-stage nephropathy and 7 type II diabetes patients without nephropathy were employed in the CyTOF test. A panel that contains 38 lineage markers was designed to monitor immune protein levels in PBMC. The unsupervised clustering analysis was performed to profile the proportion of individual cells. t-Distributed Stochastic Neighbor Embedding (t-SNE) was used to visualize the differences in DN patients' immune phenotypes. Comprehensive immune profiling revealed substantial immune system alterations in the early onset of DN, including the significant decline of B cells and the marked increase of monocytes. The level of CXCR3 was dramatically reduced in the different immune cellular subsets. The CyTOF data classified the fine-grained differential immune cell subsets in the early stage of DN. Innovatively, we identified several significant changed T cells, B cell, and monocyte subgroups in the early-stage DN associated with several potential biomarkers for developing DN, such as CTLA-4, CXCR3, PD-1, CD39, CCR4, and HLA-DR. Correlation analysis further demonstrated the robust relationship between above immune cell biomarkers and clinical parameters in the DN patients. Therefore, we provided a convincible view of understanding the immune-driven early pathogenesis of DN. Our findings exhibited that patients with DN are more susceptible to immune system disorders. The classification of fine-grained immune cell subsets in this present research might provide novel targets for the immunotherapy of DN.

Usefulness of urinary biomarkers to estimate the interstitial fibrosis surface in diabetic nephropathy with normal kidney function

BACKGROUND

Kidney biopsies of patients with diabetic nephropathy (DN) and normal kidney function may exhibit interstitial fibrosis (IF) without reduction of glomerular filtration rate because of hyperfiltration. The aim of our study was to analyze the performance of a set of biomarkers of tubular injury to estimate the extent of IF in patients with DN and normal kidney function.

PATIENTS AND METHODS

This cross-sectional study included 118 adults with DN diagnosed by kidney biopsy and GFR ≥ 90 mL/min/1.73 m2 and a control group of healthy subjects. We measured the urinary excretion of MCP-1, NGAL, KIM-1, L-FABP, β2-microglobulin and DKK-3 at the time of kidney biopsy. GFR was measured by Cr-EDTA (mGFR). IF was quantified using a quantitative morphometric procedure. Predictive multivariate models were developed to estimate the IF surface.

RESULTS

patients with DN showed significantly higher levels of DKK-3, MCP-1 and L-FABP and significantly lower levels of EGF than healthy controls. There were no significant between-group differences in the levels of β2-microglobulin, KIM-1 or NGAL. IF was negatively associated with EGF and a positively with age, proteinuria, MCP-1, DKK-3 and L-FABP but no with β2-microglobulin, KIM-1, NGAL or GFR. The best model to predict IF surface accounted for 59% of its variability and included age, proteinuria, EGF, DKK-3 and MCP-1.

CONCLUSIONS

our study provides a model to estimate the IF in DN that can be useful to assess the progression of IF in patients with normal kidney function.

Urinary Epidermal Growth Factor: A Promising "Next Generation" Biomarker in Kidney Disease

BACKGROUND

The epidermal growth factor (EGF) is a globular protein that is generated in the kidney, especially in the loop of Henle and the distal convoluted tubule. While EGF is nonexistent or hardly detectable in plasma, it is present in normal people's urine. Until now, risk stratification and chronic kidney disease (CKD) diagnosis have relied on estimated glomerular filtration rate (eGFR) and urine albumin/creatinine ratio (uACR), both of which reflect glomerular function or impairment. Tubular dysfunction, on the other hand, may also be associated with renal failure.

SUMMARY

Because decreased urine EGF (uEGF) indicates tubular atrophy and interstitial fibrosis, this biomarker, together with eGFR and uACR, may be employed in the general population for risk assessment and diagnosis of CKD. uEGF levels have been shown to correlate with intrarenal EGF mRNA expression and have been found to decrease in a variety of glomerular and non-glomerular kidney disorders.

KEY MESSAGE

uEGF, uEGF/creatinine, or uEGF/monocyte chemotactic peptide-1 are possible "new generation" biomarkers linked to a variety of kidney diseases that deserve further investigation as a single biomarker or as part of a multi-biomarker panel.

Green tea peptides ameliorate diabetic nephropathy by inhibiting the TGF-β/Smad signaling pathway in mice

Diabetic nephropathy (DN) is the most important cause of middle and late-stage chronic kidney disease. Green tea polypeptides are extracted from tea pomace, and exhibit various pharmacological effects. In this study, we analyzed the reno-protective effects of green tea peptides in diabetic db/db mice, and explored the underlying mechanisms. Peptide treatment for 5 weeks significantly reduced the blood glucose levels and other indices of diabetes, and alleviated renal injury measured in terms of blood creatinine, urea nitrogen and urinary albumin/urinary creatinine levels. Mechanistically, the green tea peptides downregulated p-Smad2/3, α-SMA, ZO-1 and vimentin proteins in the kidney tissues, and elevated Smad7. Thus, green tea peptides inhibited the deposition of ECM proteins by suppressing excessive activation of the TGF-β/Smad signaling pathway and reducing fibronectin levels. On the other hand, tea peptides ameliorated renal injury by inhibiting the production of inflammatory factors (iNOS and TNF-α) by suppressing the NF-κB signaling pathway. In addition, we confirmed the inhibitory effect of green tea peptides on the TGF-β/Smad signaling pathway in TGF-β1-stimulated HK-2 cells. Therefore, tea peptides can be considered as an effective candidate for alleviating DN.

Renin angiotensin system molecules and chemokine (C-C motif) ligand 2 (CCL2) in chronic kidney disease patients

INTRODUCTION

Studies have shown that the renin angiotensin aldosterone system (RAAS) and inflammation are related to kidney injury progression. The aim of this study was to evaluate RAAS molecules and chemokine (C-C motif) ligand 2 (CCL2) in 82 patients with chronic kidney disease (CKD).

METHODS

Patients were divided into two groups: patients diagnosed with CKD and patients without a CKD diagnosis. Glomerular filtration rate (GFR) and albumin/creatinine ratio (ACR) were determined, as well as plasma levels of angiotensin-(1-7) [Ang-(1-7)], angiotensin-converting enzyme (ACE)1, ACE2, and plasma and urinary levels of CCL2.

RESULTS

CCL2 plasma levels were significantly higher in patients with CKD compared to the control group. Patients with lower GFR had higher plasma levels of ACE2 and CCL2 and lower ratio ACE1/ACE2. Patients with higher ACR values had higher ACE1 plasma levels.

CONCLUSION

Patients with CKD showed greater activity of both RAAS axes, the classic and alternative, and higher plasma levels of CCL2. Therefore, plasma levels of RAAS molecules and CCL2 seem to be promising prognostic markers and even therapeutic targets for CKD.

Physical activity and adipokine levels in individuals with type 2 diabetes: A literature review and practical applications

We review the effects of acute and long-term physical activity on adipokine levels in individuals with type 2 diabetes (T2D). Three electronic databases were searched. Studies made in animal models were excluded, while studies based on participants with and without T2D, and also studies with type 1 diabetes were included. Of the 2,450 citations, 63 trials, including randomised control trials, cross-sectional and longitudinal studies, met our inclusion criteria. Seventy and five percent of studies reported the effects of physical activity on tumor necrosis factor-alpha (TNFα), interleukin 6 (IL-6), adiponectin, visfatin, omentin-1, and leptin levels. There are no robust results due to variations in exercise modality, intensity, duration, and also differences in cohort characteristics in the literature. Only four studies described the effects of an acute session of physical activity on adipokine levels. Overall, physical activity improves diabetes status by regulating adipokine levels. However, long-term aerobic + resistance training combined with dietary modifications is likely to be a more effective strategy for improving adipokines profiles in patients with type 2 diabetes.

Early detection of diabetic nephropathy in patient with type 2 diabetes mellitus: A review of the literature

Type 2 diabetes mellitus is a pathology of heterogeneous etiology characterized by hyperglycemia resulting from lack of insulin action, insulin secretion, or both, and the population with diabetes mellitus is predicted to be about 439 million worldwide by 2030. Prolong diabetes has been related with microvascular complications especially diabetic nephropathy. DN is the most common complication of type 2 diabetes mellitus, and it is the leading cause of end-stage renal disease worldwide. It is crucial to diagnose patients who are more sensible to develop DN for better control of the process of disease. Several factors and mechanisms contribute to the development and outcome of diabetic nephropathy. Microalbuminuria is an early marker of DN and use it as a routine for screening, but the renal damages may be happening even without microalbuminuria. There are several significant kidney damage and disease biomarkers which helps in early detection of DN. An early biomarker may allow earlier diagnosis, treatment reduces DN prevalence and slows DN progression. Therefore, this review focuses on laboratory biomarkers that are earlier, more validation of an early and specific biomarker could potentially make it possible for early diagnosis, treatment, and retardation of progression of diabetic nephropathy.

Identification of fibronectin 1 (FN1) and complement component 3 (C3) as immune infiltration-related biomarkers for diabetic nephropathy using integrated bioinformatic analysis

Immune cell infiltration (ICI) plays a pivotal role in the development of diabetic nephropathy (DN). Evidence suggests that immune-related genes play an important role in the initiation of inflammation and the recruitment of immune cells. However, the underlying mechanisms and immune-related biomarkers in DN have not been elucidated. Therefore, this study aimed to explore immune-related biomarkers in DN and the underlying mechanisms using bioinformatic approaches. In this study, four DN glomerular datasets were downloaded, merged, and divided into training and test cohorts. First, we identified 55 differentially expressed immune-related genes; their biological functions were mainly enriched in leukocyte chemotaxis and neutrophil migration. The CIBERSORT algorithm was then used to evaluate the infiltrated immune cells; macrophages M1/M2, T cells CD8, and resting mast cells were strongly associated with DN. The ICI-related gene modules as well as 25 candidate hub genes were identified to construct a protein-protein interactive network and conduct molecular complex detection using the GOSemSim algorithm. Consequently, FN1, C3, and VEGFC were identified as immune-related biomarkers in DN, and a related transcription factor-miRNA-target network was constructed. Receiver operating characteristic curve analysis was estimated in the test cohort; FN1 and C3 had large area under the curve values (0.837 and 0.824, respectively). Clinical validation showed that FN1 and C3 were negatively related to the glomerular filtration rate in patients with DN. Six potential therapeutic small molecule compounds, such as calyculin, phenamil, and clofazimine, were discovered in the connectivity map. In conclusion, FN1 and C3 are immune-related biomarkers of DN.

Regulation of Monocytes/Macrophages by the Renin-Angiotensin System in Diabetic Nephropathy: State of the Art and Results of a Pilot Study

Diabetic nephropathy (DN) is characterized by albuminuria, loss of renal function, renal fibrosis and infiltration of macrophages originating from peripheral monocytes inside kidneys. DN is also associated with intrarenal overactivation of the renin-angiotensin system (RAS), an enzymatic cascade which is expressed and controlled at the cell and/or tissue levels. All members of the RAS are present in the kidneys and most of them are also expressed in monocytes/macrophages. This review focuses on the control of monocyte recruitment and the modulation of macrophage polarization by the RAS in the context of DN. The local RAS favors the adhesion of monocytes on renal endothelial cells and increases the production of monocyte chemotactic protein-1 and of osteopontin in tubular cells, driving monocytes into the kidneys. There, proinflammatory cytokines and the RAS promote the differentiation of macrophages into the M1 proinflammatory phenotype, largely contributing to renal lesions of DN. Finally, resolution of the inflammatory process is associated with a phenotype switch of macrophages into the M2 anti-inflammatory subset, which protects against DN. The pharmacologic interruption of the RAS reduces albuminuria, improves the trajectory of the renal function, decreases macrophage infiltration in the kidneys and promotes the switch of the macrophage phenotype from M1 to M2.

Monocyte phenotype as a predictive marker for wound healing in diabetes-related foot ulcers

AIMS

Delayed healing of diabetes-related foot ulcers (DRFUs) is associated with increased macrophage and matrix metalloproteinases (MMPs) at the wound site. Whether circulating monocyte phenotype and/or MMPs are altered in association with wound healing outcome is unknown, and was investigated in this study.

METHODS

Blood was obtained from 21 participants with DRFU, at initial visit (V1), week-4 (V2), and week-8 (V3) for measurement of monocyte number (CD14⁺), phenotype (CD16, CD163) and chemokine receptors (CCRs) by flow cytometry, and circulating MMPs and TIMP-1 by ELISA.

RESULTS

Six wounds healed during the study. At V1, non-classical CD16⁺⁺ monocytes and MMP-3 were higher in healed vs unhealed (both p < 0.05). At V3, the increased %CD16⁺⁺ persisted and %CCR2⁺ was decreased in healed, but no other monocyte markers nor MMP/TIMP differed between groups. Increased wound closure rate (WCR) at V3 correlated with increased %CD16⁺⁺ monocytes and decreased MMP-2 at V1 or V1 + V2. Receiver operating characteristic (ROC) curves yielded an area-under-the-curve of %CD16⁺⁺ at V1 of 0.78 to predict ulcer healing at V3.

CONCLUSIONS

These results indicate that circulating monocyte phenotype and MMPs alter as DRFUs heal. The relationship of %CD16⁺⁺ monocytes with WCR and ROC curve suggest a predictive role of %CD16⁺⁺ monocytes for ulcer healing.

Chronic treatment with the (iso-)glutaminyl cyclase inhibitor PQ529 is a novel and effective approach for glomerulonephritis in chronic kidney disease

Glomeruli and renal tubule injury in chronic kidney disease (CKD) is reported to involve induction of macrophage activation through the CCL2/CCR2 axis. The effects of inhibitors of the CCL2/CCR2 axis, such as anti-CCL2 antibody and CCR2 antagonist, on kidney function in animal models or humans with kidney dysfunction have been demonstrated. The N-terminal glutamine on immature CCL2 is replaced with pyroglutamate (pE) by glutaminyl cyclase (QC) and isoQC. pE-CCL2 is stable and resistant to peptidases. We hypothesized that inhibiting QC/isoQC activity would lead to the degradation of CCL2, thereby ameliorating CKD and reducing kidney inflammation. To test this hypothesis, we investigated the renoprotective properties of the QC/isoQC inhibitor PQ529 in anti-glomerular basement membrane (GBM) antibody-induced glomerulonephritis Wistar Kyoto (WKY) rats. Three-week repeated administration of PQ529 (30 and 100 mg/kg, twice daily) significantly reduced the serum and urine CCL2 and urinary protein excretion in a dose-dependent manner. Correlations between the urinary protein level and serum or urinary CCL2 levels were confirmed in tested animals. Repeated administration of PQ529 significantly reduced the expression of CD68, a macrophage marker, in the kidney cortex and mononuclear infiltration into the tubulointerstitium. In addition, decreased levels of urinary KIM-1, β2 microglobulin, and clusterin were detected, suggesting the inhibition of inflammation in both the proximal and distal tubules. These results suggest that PQ529 suppresses the progression of inflammation-induced renal dysfunction by inhibiting the CCL2/CCR2 axis. Inhibition of QC/isoQC may thus be a viable alternative therapeutic approach for treating glomerulonephritis and CKD patients.

Inflammatory Biomarkers Levels in T2DM Emirati Patients with Diabetic Neuropathy

INTRODUCTION

Previous studies have suggested the involvement of chronic low-grade inflammation in the pathogenesis of diabetic neuropathy (DNP). However, none of these studies have examined the levels of monocyte chemoattractant protein-1 (MCP-1) in type 2 diabetes mellitus (T2DM) patients with confirmed diagnosis of neuropathy. Therefore, the present study aims to investigate the levels of MCP-1 along with IL-6, IL-8 and TGF-β in patients with T2DM and confirmed neuropathy and identify correlations, if any, between MCP-1 and other parameters.

METHODS

A single center cross-sectional clinical study was conducted at University Hospital Sharjah (UHS) and University of Sharjah. One hundred and two patients with T2DM were recruited from diabetes clinics at UHS and were stratified into different groups based on diagnosis of DNP and other parameters. Several analyses were conducted to evaluate and compare the levels of MCP-1, IL-6, IL-8, and TGF-β across these groups of patients and identify correlations, if any, between MCP-1 and other variables.

RESULTS

A significant increase was found in the levels of MCP-1 in T2DM patients with DNP compared to the patients without DNP (p=0.002, p-adj=0.007). Further analysis has shown that levels of IL-8 (p=0.008) and TGF-β (p=0.06) were increased and decreased, respectively, in patients with DNP compared to patients without DNP. Moreover, strong correlations were found between MCP-1, IL-8 and TGF-β levels.

CONCLUSION

The key finding of the present study is the significant elevation in levels of MCP-1 in T2DM patients with DNP compared to the patients without DNP and IL-8 and TGF-β were strong predictors of MCP-1 increased levels.

Current Challenges and Future Perspectives of Renal Tubular Dysfunction in Diabetic Kidney Disease

Over decades, substantial progress has been achieved in understanding the pathogenesis of proteinuria in diabetic kidney disease (DKD), biomarkers for DKD screening, diagnosis, and prognosis, as well as novel hypoglycemia agents in clinical trials, thereby rendering more attention focused on the role of renal tubules in DKD. Previous studies have demonstrated that morphological and functional changes in renal tubules are highly involved in the occurrence and development of DKD. Novel tubular biomarkers have shown some clinical importance. However, there are many challenges to transition into personalized diagnosis and guidance for individual therapy in clinical practice. Large-scale clinical trials suggested the clinical relevance of increased proximal reabsorption and hyperfiltration by sodium-glucose cotransporter-2 (SGLT2) to improve renal outcomes in patients with diabetes, further promoting the emergence of renal tubulocentric research. Therefore, this review summarized the recent progress in the pathophysiology associated with involved mechanisms of renal tubules, potential tubular biomarkers with clinical application, and renal tubular factors in DKD management. The mechanism of kidney protection and impressive results from clinical trials of SGLT2 inhibitors were summarized and discussed, offering a comprehensive update on therapeutic strategies targeting renal tubules.

Praliciguat inhibits progression of diabetic nephropathy in ZSF1 rats and suppresses inflammation and apoptosis in human renal proximal tubular cells

Praliciguat, a clinical-stage soluble guanylate cyclase (sGC) stimulator, increases cGMP via the nitric oxide-sGC pathway. Praliciguat has been shown to be renoprotective in rodent models of hypertensive nephropathy and renal fibrosis. In the present study, praliciguat alone and in combination with enalapril attenuated proteinuria in the obese ZSF1 rat model of diabetic nephropathy. Praliciguat monotherapy did not affect hemodynamics. In contrast, enalapril monotherapy lowered blood pressure but did not attenuate proteinuria. Renal expression of genes in pathways involved in inflammation, fibrosis, oxidative stress, and kidney injury was lower in praliciguat-treated obese ZSF1 rats than in obese control rats; fasting glucose and cholesterol were also lower with praliciguat treatment. To gain insight into how tubular mechanisms might contribute to its pharmacological effects on the kidneys, we studied the effects of praliciguat on pathological processes and signaling pathways in cultured human primary renal proximal tubular epithelial cells (RPTCs). Praliciguat inhibited the expression of proinflammatory cytokines and secretion of monocyte chemoattractant protein-1 in tumor necrosis factor-α-challenged RPTCs. Praliciguat treatment also attenuated transforming growth factor-β-mediated apoptosis, changes to a mesenchyme-like cellular phenotype, and phosphorylation of SMAD3 in RPTCs. In conclusion, praliciguat improved proteinuria in the ZSF1 rat model of diabetic nephropathy, and its actions in human RPTCs suggest that tubular effects may contribute to its renal benefits, building upon strong evidence for the role of cGMP signaling in renal health.

Pentoxifylline mitigates renal glycoxidative stress in obese mice by inhibiting AGE/RAGE signaling and increasing glyoxalase levels

AIM

The pharmacological properties of pentoxifylline have been re-evaluated, particularly in chronic kidney disease in diabetes, favored by its anti-inflammatory action. Definitive evidences of renal outcomes are lacking, which indicates the need for investigation of novel mechanisms of action of pentoxifylline. We postulated that components associated with the metabolism of advanced glycation end products (AGEs) may be modulated by pentoxifylline, which consequently decreases the detrimental effects of obesity on kidneys.

MAIN METHODS

C57BL-6J mice were fed a high-fat diet for 14 weeks and treated with 50 mg/kg pentoxifylline during the last 7 weeks. Changes in the renal levels of AGE metabolism-associated components were investigated, with particular focus on the receptor for AGEs (RAGE), its downstream components, and components related to AGE detoxification, including glyoxalase 1 (GLO 1).

KEY FINDINGS

Pentoxifylline reduced body weight gain, improved insulin sensitivity and glucose tolerance, downregulated biomarkers of glycoxidative stress, and enhanced plasma paraoxonase 1 activity. In the kidneys, pentoxifylline inhibited glomerular expansion, lipid deposition, reduced pro-inflammatory cytokine levels, and induced the activation of AMP-activated protein kinase. Pentoxifylline inhibited the renal accumulation of AGEs and reduced the levels of RAGE and its downstream components, and consequently mitigated oxidative stress and apoptosis. Pentoxifylline also increased the renal levels of GLO 1 and the activities of antioxidant enzymes. Urinary albumin levels were observed to be lowered, which reconfirmed the antialbuminuric effects of pentoxifylline.

SIGNIFICANCE

The novel mechanisms of action help explain the renoprotective effects of pentoxifylline and the attenuation of obesity-associated renal complications related to glycoxidative stress.

Biomarkers of Acute and Chronic Kidney Disease

The current unidimensional paradigm of kidney disease detection is incompatible with the complexity and heterogeneity of renal pathology. The diagnosis of kidney disease has largely focused on glomerular filtration, while assessment of kidney tubular health has notably been absent. Following insult, the kidney tubular cells undergo a cascade of cellular responses that result in the production and accumulation of low-molecular-weight proteins in the urine and systemic circulation. Modern advancements in molecular analysis and proteomics have allowed the identification and quantification of these proteins as biomarkers for assessing and characterizing kidney diseases. In this review, we highlight promising biomarkers of kidney tubular health that have strong underpinnings in the pathophysiology of kidney disease. These biomarkers have been applied to various specific clinical settings from the spectrum of acute to chronic kidney diseases, demonstrating the potential to improve patient care.

The Hypoglycemic and Renal Protection Properties of Crocin via Oxidative Stress-Regulated NF-κB Signaling in db/db Mice

Background

As the main ingredient of Crocus sativus L. (Iridaceae) extract, crocin- I (CR) has been reported to show various pharmacological activities. The aim of this study was to investigate the hypoglycemic and renal protection properties of CR in db/db mice.

Methods

Eight-week-old db/db mice were treated with metformin (Met) (100 mg/kg) and CR (50 mg/kg) for eight weeks.

Results

CR treatment showed hypoglycemic functions indicated by reduced bodyweight, food and water intake, plasma glucose, and serum levels of glycated hemoglobin A1c. Additionally, the CR group showed increased serum levels of insulin and pyruvate kinase, hypolipidemic functions indicated by the suppressed levels of total cholesterol and triglyceride, and enhanced levels of high-density lipoprotein cholesterol, which are also indicators of hypoglycemic functions. The renal protection function of CR was demonstrated by its protection of renal structures and its regulation of potential indicators of nephropathy. The anti-oxidation and anti-inflammation effects of CR were verified by enzyme-linked immunosorbent assay. In the kidneys of db/db mice, CR decreased the expression of phospho-IκBα and phospho-nuclear factor-κB (NF-κB), whereas it enhanced the expression of nuclear respiratory factor 2, manganese superoxide dismutase 1, heme oxygenase-1, and catalase.

Conclusions

The anti-diabetic and anti-diabetic nephritic effects of CR were related to its modulation of oxidative stress-mediated NF-κB signaling.

The Role of Chemokines and Chemokine Receptors in Diabetic Nephropathy

Kidney function decline is one of the complications of diabetes mellitus and may be indicated as diabetic nephropathy (DN). DN is a chronic inflammatory disease featuring proteinuria and a decreasing glomerular filtration rate. Despite several therapeutic options being currently available, DN is still the major cause of end-stage renal disease. Accordingly, widespread innovation is needed to improve outcomes in patients with DN. Chemokines and their receptors are critically involved in the inflammatory progression in the development of DN. Although recent studies have shown multiple pathways related to the chemokine system, the specific and direct effects of chemokines and their receptors remain unclear. In this review, we provide an overview of the potential role and mechanism of chemokine systems in DN proposed in recent years. Chemokine system-related mechanisms may provide potential therapeutic targets in DN.

Inflammatory Targets in Diabetic Nephropathy

One of the most frequent complications in patients with diabetes mellitus is diabetic nephropathy (DN). At present, it constitutes the first cause of end stage renal disease, and the main cause of cardiovascular morbidity and mortality in these patients. Therefore, it is clear that new strategies are required to delay the development and the progression of this pathology. This new approach should look beyond the control of traditional risk factors such as hyperglycemia and hypertension. Currently, inflammation has been recognized as one of the underlying processes involved in the development and progression of kidney disease in the diabetic population. Understanding the cascade of signals and mechanisms that trigger this maladaptive immune response, which eventually leads to the development of DN, is crucial. This knowledge will allow the identification of new targets and facilitate the design of innovative therapeutic strategies. In this review, we focus on the pathogenesis of proinflammatory molecules and mechanisms related to the development and progression of DN, and discuss the potential utility of new strategies based on agents that target inflammation.

IL-20 in Acute Kidney Injury: Role in Pathogenesis and Potential as a Therapeutic Target

Acute kidney injury (AKI) causes over 1 million deaths worldwide every year. AKI is now recognized as a major risk factor in the development and progression of chronic kidney disease (CKD). Diabetes is the main cause of CKD as well. Renal fibrosis and inflammation are hallmarks in kidney diseases. Various cytokines contribute to the progression of renal diseases; thus, many drugs that specifically block cytokine function are designed for disease amelioration. Numerous studies showed IL-20 functions as a pro-inflammatory mediator to regulate cytokine expression in several inflammation-mediated diseases. In this review, we will outline the effects of pro-inflammatory cytokines in the pathogenesis of AKI and CKD. We also discuss the role of IL-20 in kidney diseases and provide a potential therapeutic approach of IL-20 blockade for treating renal diseases.

Mechanisms of Herbal Nephroprotection in diabetes mellitus

Diabetic nephropathy (DN) is a leading cause of kidney morbidity. Despite the multilayered complexity of the mechanisms involved in the pathogenesis of DN, the conventional treatment is limited to just a few drug classes fraught with the risk of adverse events, including the progression of renal dysfunction. Phytoceuticals offer a promising alternative as they act on the many-sidedness of DN pathophysiology, multitargeting its intricacies. This paper offers a review of the mechanisms underlying the protective action of these phytoagents, including boosting the antioxidant capabilities, suppression of inflammation, averting the proliferative and sclerosing/fibrosing events. The pathogenesis of DN is viewed as a continuum going from the original offense, high glucose, through the noxious products it generates (advanced glycation end-products, products of oxidative and nitrosative stress) and the signaling chains consequently brought into action, to the harmful mediators of inflammation, sclerosis, and proliferation that eventually lead to DN, despite the countervailing attempts of the protective mechanisms. Special attention was given to the various pathways involved, pointing out the ability of the phytoagents to hinder the deleterious ones (especially those leading to, driven by, or associated with TGF-β activation, SREBP, Smad, MAPK, PKC, NF-κB, NLRP3 inflammasome, and caspase), to promote the protective ones (PPAR-α, PPAR-γ, EP4/Gs/AC/cAMP, Nrf2, AMPK, and SIRT1), and to favorably modulate those with potentially dual effect (PI3K/Akt). Many phytomedicines have emerged as potentially useful out of in vitro and in vivo studies, but the scarcity of human trials seriously undermines their usage in the current clinical practice-an issue that stringently needs to be addressed.

Cardio-ankle vascular index is linked to deranged metabolic status, especially high HbA1c and monocyte-chemoattractant-1 protein, in predialysis chronic kidney disease

INTRODUCTION AND PURPOSE

Arterial stiffness is an independent predictor of cardiovascular disease in chronic kidney disease (CKD). Cardio-ankle vascular index (CAVI) is a newly developed method used to assess arterial stiffness, independent of changes in blood pressure. CAVI reflects stiffness and atherosclerosis at the thoracic, abdominal, common iliac, femoral, and tibial artery levels. In predialysis stage 3-5 diabetic and nondiabetic CKD patients, CAVI levels and its relation to atherosclerosis-associated risk factors including monocyte-chemoattractant protein-1 (MCP-1), sclerostin, fibroblast growth factor-23 (FGF-23), Klotho, and 25-OH vitamin D were determined.

MATERIALS AND METHODS

The study was performed on three age-matched and gender-matched groups. Group 1 included 46 stage 3-5 nondiabetic CKD patients, group 2 included 44 stage 3-5 diabetic CKD patients, and group 3 included 44 non-uremic controls. All subjects underwent CAVI measurement. Serum glycated hemoglobin (HbA1c), total calcium, phosphorus, parathormone, FGF-23, Klotho, MCP-1, sclerostin, and 25-OH vitamin D were determined using standard methods.

RESULTS

CAVI level was 8.22 ± 0.18 m/s in diabetic CKD patients and significantly higher than in nondiabetic CKD (7.61 ± 0.18 m/s) and control (7.59 ± 0.17 m/s) patients. FGF-23 level was higher in the CKD groups than controls but not statistically significant. MCP-1 level was significantly higher in diabetic CKD patients. Klotho and sclerostin levels were significantly lower in diabetic CKD patients. In the whole cohort, CAVI showed positive correlations with age (r = 0.447, p < 0.0001), smoking (r = 0.331, p = 0.035), mean arterial blood pressure (MABP; r = 0.327, p < 0.0001), fasting blood glucose (r = 0.185, p = 0.033), and HbA1c (r = 0.258, p = 0.003). Stepwise regression analysis revealed that age (p = 0.0001, B = 0.461), MABP (p < 0.0001, B = 0.365), HbA1c (p = 0.003, B = 0.251), and MCP-1 (p = 0.013, B = 0.214) independently predicted CAVI levels.

CONCLUSION

Our results indicate higher CAVI levels, therefore, resulting in increased arterial stiffness in the setting of diabetic CKD. Apart from age and MABP, deranged metabolic status, especially increased HbA1c and MCP-1 levels, is also independently associated with increasing CAVI levels in CKD patients. These results emphasize the importance of metabolic control in the development of arterial stiffness in CKD patients, which is an early predictor of developing cardiovascular complications.

Zafirlukast, a Cysteinyl Leukotriene Receptor 1 Antagonist, Reduces the Effect of Advanced Glycation End-Products in Rat Renal Mesangial Cells In Vitro

Background

Zafirlukast is an antagonist of cysteinyl leukotriene receptor 1 (CysLTR1). Advanced glycation end-products (AGEs) are formed by the glycation of lipids and proteins in hyperglycemia, including diabetes mellitus. Zafirlukast has not previously been studied in diabetic nephropathy. This study aimed to investigate the effects of zafirlukast on rat renal mesangial cells cultured with AGEs in vitro.

Material/Methods

Mesangial cells were cultured in AGEs (0, 20, 50, 100 μg/ml), and with AGEs (100 μg/ml) and zafirlukast (2.5 μm, 5 μm, and 100 μm). An enzyme-linked immunoassay (ELISA) was used to measure the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and monocyte chemoattractant protein-1 (MCP-1). Reactive oxygen species (ROS) were assessed by intracellular fluorescence measurement of 2′-7′-dichlorodihydrofluorescein diacetate (DCFH-DA), and detection kits were used to measure malondialdehyde (MDA), lactate dehydrogenase (LDH), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD). Cell apoptosis was assessed by flow cytometry, and Western blot was used to measure protein levels.

Results

In mesangial cells cultured with AGEs, markers of inflammation, oxidative stress, and apoptosis and levels of CysLTR1 increased, and these effects were reduced by zafirlukast in a dose-dependent manner. The effects of zafirlukast as a CysLTR1 antagonist protected mesangial cells from the effects of AGE in vitro.

Conclusions

Zafirlukast, a CysLTR1 antagonist, reduced the levels of inflammatory cytokines, markers of oxidative stress, and cell apoptosis induced by AGE in mesangial cells in a dose-dependent way. Future in vivo studies are needed to investigate the potential role for zafirlukast in models of diabetic nephropathy.

hs-CRP Is Associated With Incident Diabetic Nephropathy: Findings From the Jackson Heart Study

OBJECTIVE

African Americans (AA) suffer disproportionately from diabetic nephropathy (DN). C-reactive protein (CRP) has been associated with prevalent DN, but its association with incident DN in AA is unknown. We examined hs-CRP and incident DN in AA.

RESEARCH DESIGN AND METHODS

We conducted a longitudinal analysis of data from exams 1, 2, and 3 in 4,043 eligible Jackson Heart Study (JHS) participants. Participants with DN or without hs-CRP at exam 1 were excluded. Incident DN was defined as urinary albumin-to-creatinine ratio (ACR) >30 mg/g or self-reported dialysis/transplantation and type 2 diabetes mellitus (DM) or HbA_1c >6.5% by exam 2 or 3 among participants free of DN at exam 1. Kaplan-Meier curves examined DN event-free survival probability by hs-CRP. With Cox proportional hazards regression we estimated hazard ratios (HRs) and 95% CI for DN by hs-CRP tertiles, adjusting for demographics and clinical and laboratory data.

RESULTS

During 7.8 years of median follow-up time, participants who developed DN had significantly higher baseline hs-CRP, age, fasting glucose, triglycerides, ACR, systolic blood pressure, waist circumference, and duration of DM (P < 0.05). The overall incident rate of DN was 7.9%. The mean time to incident DN was shorter for participants with hs-CRP in the high tertile (>4.24 mg/L) than in the low tertile (<1.46 mg/L); P < 0.001. Participants with high hs-CRP had higher incidence of DN (HR 2.34, 95% CI 1.04-5.24) versus the reference group.

CONCLUSIONS

Inflammation, as measured by hs-CRP levels, may be associated with incident DN in AA. Further studies are warranted to replicate and elucidate the basis for this association.

Anti-Diabetic Nephropathy Activities of Polysaccharides Obtained from Termitornyces albuminosus via Regulation of NF-κB Signaling in db/db Mice

Termitornyces albuminosus is a kind of traditional Chinese edible fungus rich in nutrients and medicinal ingredients, and it has anti-oxidative, analgesic and anti-inflammatory effects. However, the hypoglycemic and nephroprotective effects of polysaccharides separated from T. albuminosus (PTA) have not been reported. The properties of PTA were analyzed in a BKS.Cg-Dock7^m +/+ Lepr^db/JNju (db/db) mouse model of diabetes. After the administration of PTA for eight weeks, the hypoglycemic and hypolipidemic activities of PTA in the db/db mice were assessed. The results of a cytokine array combined with an enzyme-linked immunosorbent assay confirmed the anti-oxidative and anti-inflammatory activities of PTA. An eight-week administration of PTA caused hypoglycemic and hypolipidemic functioning, as indicated by suppressed plasma glucose levels, as well as the modulation of several cytokines related to glycometabolism, in the sera and kidneys of the mice. PTA treatment also had a protective effect on renal function, restoring renal structures and regulating potential indicators of nephropathy. In the kidneys of the db/db mice, PTA treatment reduced the activation of protein kinase B, the inhibitor of κB kinase alpha and beta, and the inhibitor of κB alpha and nuclear factor-κB (NF-κB). We establish the hypoglycemic, hypolipidemic, and anti-diabetic nephropathy effects of PTA, and we find that the renal protection effects of PTA may be related to anti-inflammatory activity via the regulation of NF-κB signaling.

The Modern Western Diet Rich in Advanced Glycation End-Products (AGEs): An Overview of Its Impact on Obesity and Early Progression of Renal Pathology

Advanced glycation end-products (AGEs) are an assorted group of molecules formed through covalent bonds between a reduced sugar and a free amino group of proteins, lipids, and nucleic acids. Glycation alters their structure and function, leading to impaired cell function. They can be originated by physiological processes, when not counterbalanced by detoxification mechanisms, or derive from exogenous sources such as food, cigarette smoke, and air pollution. Their accumulation increases inflammation and oxidative stress through the activation of various mechanisms mainly triggered by binding to their receptors (RAGE). So far, the pathogenic role of AGEs has been evidenced in inflammatory and chronic diseases such as chronic kidney disease, cardiovascular disease, and diabetic nephropathy. This review focuses on the AGE-induced kidney damage, by describing the molecular players involved and investigating its link to the excess of body weight and visceral fat, hallmarks of obesity. Research regarding interventions to reduce AGE accumulation has been of great interest and a nutraceutical approach that would help fighting chronic diseases could be a very useful tool for patients’ everyday lives.

Metformin inhibits TGF-beta 1-induced MCP-1 expression through BAMBI-mediated suppression of MEK/ERK1/2 signalling

AIMS

Metformin is a biguanide derivative widely used for the treatment of type 2 diabetes mellitus. Recent evidence demonstrates that this anti-hyperglycaemic drug exerts renal protective effects, yet the mechanisms remain poorly understood. monocyte chemoattractant protein 1 (MCP-1) has been recognized as a key mediator of renal fibrosis in chronic kidney diseases, including diabetic nephropathy. This study aimed to investigate the effects of metformin on transforming growth factor beta 1 (TGF-β1)-induced MCP-1 expression and the underlying mechanisms in rat renal tubular epithelial cells.

METHODS

Rat renal tubular epithelial cell line NRK-52E cells were stimulated with TGF-β1 and/or metformin. The messenger RNA (mRNA) of MCP-1 and bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) was evaluated by real-time quantitative polymerase chain reaction. MCP-1 protein was measured by enzyme linked immunosorbent assay (ELISA). Total and phosphorylated extracellular signal-regulated kinases 1/2 (ERK1/2) was evaluated by western blot. Down- and upregulation of BAMBI were achieved by RNA interference targeting BAMBI and lentiviral vector-mediated overexpression of the BAMBI gene, respectively. Cell viability was analysed using Cell Counting Kit 8 (CCK-8) reagents.

RESULTS

Stimulation with TGF-β1 resulted in the increased expression of MCP-1 and decreased expression of BAMBI in NRK-52E cells. Metformin inhibited the expression of MCP-1 in NRK-52E cells. Pretreatment with metformin suppressed upregulation of MCP-1 and downregulation of BAMBI, as well as phosphorylation of ERK1/2 induced by TGF-β1. U0126, a specific inhibitor for mitogen-activated and extracellular signal-regulated kinase kinases 1/2 (MEK-1/2), completely blocked TGF-β1-induced MCP-1 expression. Knockdown of the BAMBI gene promoted phosphorylation of ERK1/2 and TGF-β1-induced expression of MCP-1. Overexpression of BAMBI inhibited phosphorylation of ERK1/2 and TGF-β1-induced upregulation of MCP-1.

CONCLUSION

In rat renal tubular epithelial cells, metformin prevents TGF-β1-induced MCP-1 expression, in which BAMBI-mediated inhibition of MEK/ERK1/2 might be involved.

Association of urinary monocyte chemoattractant protein-1 (MCP-1) and kidney injury molecule-1 (KIM-1) with risk factors of diabetic kidney disease in type 2 diabetes patients

PURPOSE

Urinary kidney injury molecule-1 and monocyte chemoattractant protein-1 are significance factors in the diagnosis and intervention of diabetic kidney diseases. This study determined levels of these proteins in diabetic patients with varying degrees of kidney disease and assessed their relationship with risk factors associated with diabetic kidney diseases.

METHODS

A total of 185 patients with type 2 diabetes were divided into three groups [low risk (n = 47), moderate risk (n = 63), and high risk (n = 75)] based on the severity of diabetic kidney disease according to kidney disease: improving global outcomes guidelines. Both urinary kidney injury molecule-1 and monocyte chemoattractant protein-1 levels were measured by enzyme-linked immunosorbent assay. Student`s t test, analysis of variance, and Spearman's correlation were used for statistical analysis.

RESULTS

The kidney injury molecule-1-to-creatinine ratio (P = 0.035) and monocyte chemoattractant protein-1-to-creatinine ratio (P < 0.001) increased significantly with the increase in kidney disease severity and varied according to different albuminuria statuses and estimated glomerular-filtration rates. The monocyte chemoattractant protein-1-to-creatinine ratio showed a significant correlation with hemoglobin A1c (P = 0.002) and inflammatory marker levels (interleukin-6, P = 0.005; tumor necrosis factor-α, P < 0.001).

CONCLUSION

Urinary levels of both kidney injury molecule-1 and monocyte chemoattractant protein-1 represent distinguishing markers for the evaluation of diabetic kidney disease progression according to the associated degrees of albuminuria or/and the estimated glomerular-filtration rate. In addition, correlations between urinary monocyte chemoattractant protein-1 and glycemic and inflammatory marker levels revealed the role of hyperglycemia and chronic inflammation in the pathogenesis of diabetic kidney disease.

Effects of Brazilian green propolis on proteinuria and renal function in patients with chronic kidney disease: a randomized, double-blind, placebo-controlled trial

Background

Chronic kidney disease (CKD) is a public health problem worldwide, and proteinuria is a well-established marker of disease progression in CKD patients. Propolis, a natural resin produced by bees from plant materials, has anti-inflammatory, immunomodulatory, and anti-oxidant properties, as well as having been shown to have an antiproteinuric effect in experimental CKD. The aim of this study was to evaluate the impact of Brazilian green propolis extract on proteinuria reduction and the changes in the estimated glomerular filtration rate (eGFR).

Methods

This was a randomized, double-blind, placebo-controlled study including patients with CKD caused by diabetes or of another etiology, 18–90 years of age, with an eGFR of 25–70 ml/min per 1.73 m² and proteinuria (urinary protein excretion > 300 mg/day) or micro- or macro-albuminuria (urinary albumin-to-creatinine ratio > 30 mg/g or > 300 mg/g, respectively). We screened 148 patients and selected 32, randomly assigning them to receive 12 months of Brazilian green propolis extract at a dose of 500 mg/day (n = 18) or 12 months of a placebo (n = 14).

Results

At the end of treatment, proteinuria was significantly lower in the propolis group than in the placebo group—695 mg/24 h (95% CI, 483 to 999) vs. 1403 mg/24 h (95% CI, 1031 to 1909); P = 0.004—independent of variations in eGFR and blood pressure, which did not differ between the groups during follow-up. Urinary monocyte chemoattractant protein-1 was also significantly lower in the propolis group than in the placebo group—58 pg/mg creatinine (95% CI, 36 to 95) vs. 98 pg/mg creatinine (95% CI, 62 to 155); P = 0.038.

Conclusions

Brazilian green propolis extract was found to be safe and well tolerated, as well as to reduce proteinuria significantly in patients with diabetic and non-diabetic CKD.

Trial Registration.

(ClinicalTrials.gov number NCT02766036. Registered: May 9, 2016).

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1337-7) contains supplementary material, which is available to authorized users.

MG132 protects against renal dysfunction by regulating Akt-mediated inflammation in diabetic nephropathy

Diabetic nephropathy (DN), the leading cause of end-stage renal disease (ESRD). To date, mounting evidence has shown that inflammation may contribute to the pathogenesis of DN. Recent reports have shown that proteasome inhibitors display cytoprotection by reducing the phosphorylation of Akt, a serine/threonine kinase, plays a critical role in cellular survival and metabolism and can crosstalk with inflammation. Therefore, we hypothesized that MG132, specific proteasome inhibitor, could provide renoprotection by suppressing Akt-mediated inflammation in DN. In vivo, male Sprague-Dawley rats were divided into normal control group (NC), diabetic nephropathy group (DN), DN model plus MG132 treatment group (MG132), and DN model plus deguelin treatment group (Deguelin)(deguelin, a specific inhibitor of Akt). In vitro, a human glomerular mesangial cell lines (HMCs) was exposed to 5.5 mmol/L glucose (CON), 30 mmol/L glucose (HG), 30 mmol/L glucose with 0.5 umol/L MG132 (MG132) and 30 mmol/L glucose with 5 umol/L deguelin (Deguelin). Compared with NC, DN showed a significant increase in the urinary protein excretion rate and inflammatory cytokines, as well as p-Akt. Compared with CON, HMCs co-cultured with HG was notably proliferated, which is in accord with α-smooth muscle actin (α-SMA) expression. These alterations were inhibited by administration of MG132 or deguelin. In conclusion, MG132 significantly inhibits the development of DN by regulating Akt phosphorylation-mediated inflammatory activation.

From Renal Biomarkers to Therapeutic Targets: The Use of Monocyte Chemoattractant Protein 1, Transforming Growth Factor-Beta, and Connective Tissue Growth Factor in Diabetic Nephropathy and Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

In an ideal world, every condition would have a sensitive and specific marker that could be measured in a noninvasive or minimally invasive way. Instead, the medical community depends on invasive biomarkers, which carry inherent risks, to make a diagnosis and plan treatment. In this review article, the current state of research into biomarkers for a range of kidney diseases is discussed, beginning with those biomarkers that are already in clinical use and then moving to conditions for which no validated biomarker yet exists. This review focusses on diabetic nephropathy at the proteinuric end of the spectrum and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis at the nephritic end. An interesting feature is that the same biomarker, monocyte chemoattractant protein-1 (MCP-1, also known as CCL2), has been identified as a potential target in both conditions, which suggests a shared pathogenic process that results in two very distinct clinical presentations. One of the major limiting features of research into this area, particularly for ANCA-associated vasculitis, is the recruitment of a sufficient number of patients to generate strong enough evidence to justify the biomarker’s routine use; this overlap in biomarkers may enable research in one condition to be applied more generally. In addition to their role as biomarkers, these molecules are also therapeutic targets, and some early research has been carried out to investigate this. Overall, this review brings together research from diverse fields to focus attention on the outstanding areas and the future areas that warrant further investigation.

Kaempferol attenuates diabetic nephropathy by inhibiting RhoA/Rho-kinase mediated inflammatory signalling

RhoA/Rho-associated coiled-coil forming protein serine/threonine kinase (ROCK) has appeared as a potential therapeutic target in numerous diseases, because of its preventing action on various enzymes providing antioxidant and cytoprotective action. Progression and pathophysiology of diabetic nephropathy have also shown potential involvement of oxidative stress and inflammatory pathways. In the present study, we investigated the effect of kaempferol on hyperglycemia-induced activation of RhoA kinase and associated inflammatory signaling cascade. Currently there is only small literature available on the mechanism of anti-diabetic and nephroprotective action of this compound, which creates a void. Therefore, we focused here on the investigation of molecular mechanisms for kaempferol by means of in vitro testing, using rat (NRK-52E) and human renal tubular epithelial cells (RPTEC). Our findings suggest that kaempferol inhibits hyperglycemia-induced activation of RhoA and decreased oxidative stress, pro-inflammatory cytokines (TNF-α and IL-1β) and fibrosis (TGF-β1 expression, extracellular matrix protein expression) in NRK-52E and RPTEC cells. Therefore, kaempferol can be used as a potential therapeutic for the treatment of diabetic nephropathy.

Xiao-Shen-Formula, a Traditional Chinese Medicine, Improves Glomerular Hyper-Filtration in Diabetic Nephropathy via Inhibiting Arginase Activation and Heparanase Expression

Hyperglycemia induces glomerular hyper-filtration, which contributes to the development of diabetic nephropathy (DN), a condition that remains a challenge for treatment. The present study investigated the effect of Xiao-Shen-Formula (XSF) used for treatment of renal injury in type 1 DN mice model induced by streptozotocin (STZ) and its underlying mechanism in cultured human glomerular endothelial cell (hGECs). Studies were performed using control, diabetic DN, DN treated with XSF groups (1 g/kg/d, LXSF or 3 g/kg/d, HXSF) for 6 weeks and hGECs were post-treated with mice serum containing HXSF (MS-HXSF) and arginase inhibitor (ABH, 100 μM) in high glucose medium. HXSF treatment restored STZ-induced renal hyper-filtration, glomerulosclerosis, renal microvascular remodeling and the increased levels of systemic reactive oxidative species and inflammatory cytokines, accompanied by preventing the decreased expression of glomerular heparin sulfate and the increased levels of cortical heparanase and argianse2 protein and arginase activity. In hGECs study, MS-HXSF ameliorated the enhancement in arginase activity, the protein/mRNA expression of heparanase, mRNA levels of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, monocyte chemoattractant protein-1 and permeability of hGECs monolayers as well as the depression of nitric oxide production. Besides all these protective effects, XSF blunted the mRNA expression of TNF-α in vivo and vitro studies as well, which was not changed by the post-treatment of ABH or HXSF plus ABH. This study demonstrated that the protective effect of XSF might be related with vascular prevention, anti-inflammation and anti-oxidation through intervening multi-targets including glomerular endothelial arginase-heparanase signaling pathway in DN model.

Urinary epidermal growth factor, monocyte chemoattractant protein-1 or their ratio as predictors for rapid loss of renal function in type 2 diabetic patients with diabetic kidney disease

BACKGROUND

Increased monocyte chemoattractant protein-1 (MCP-1) and decreased epidermal growth factor (EGF) are promising biomarkers to predict progressive decline in kidney function in non-diabetic kidney diseases. We aimed to evaluate the performance of urinary EGF, MCP-1 or their ratio in predicting rapid decline of GFR in a cohort of Type 2 diabetic patients (T2DM) with diabetic kidney disease (DKD).

METHODS

T2DM patients (n = 83) with DKD at high risk for renal progression were followed up prospectively. The baseline urine values of MCP-1 to creatinine ratio (UMCP-1), EGF to creatinine ratio (UEGF), EGF to MCP-1 ratio (UEGF/MCP-1) and albumin to creatinine ratio (UACR) were measured. The primary outcome was a decline in estimated glomerular filtration rate (GFR) of ≥25% yearly from baseline.

RESULTS

During follow-up time of 23 months, patients with rapid decline in estimated GFR of ≥25% yearly from baseline had significantly higher baseline levels of UMCP-1, and UACR and lower UEGF and UEGF/MCP-1 ratio. All renal biomarkers predicted primary outcomes with ROC (95%CI) for UMCP-1=0.73 (0.62-0.84), UEGF=0.68 (0.57-0.80), UEGF/MCP-1=0.74 (0.63-0.85), and UACR =0.84 (0.75-0.93). By univariate analysis, blood pressure, GFR, UACR, UMCP-1, UEGF, and UEGF/MCP-1 were associated with rapid decline GFR. By multivariate analysis, UACR, systolic blood pressure, and UMCP-1 or UEGF/MCP-1 were independently associated with rapid GFR decline.

CONCLUSIONS

UMCP-1 or UEGF/MCP-1 ratio were associated with rapid renal progression independent from conventional risk factors in DKD.

Association between MCP-1 2518 A>G gene polymorphism and chronic kidney disease

Monocyte chemoattractant protein-1 (MCP-1) is involved in the pathogenesis of chronic kidney diseases (CKD). MCP-1 2518 A>G gene polymorphism is associated with MCP-1 status. We performed a meta-analysis to assess the association between MCP-1 2518 A>G gene polymorphism and CKD risk. The eligible studies regarding the relationship between MCP-1 2518 A>G gene polymorphism and CKD risk were searched through electronic databases. The pooled odds ratios (ORs) and its 95% confidence intervals (CIs) were calculated by using a fixed-effects model, or in the presence of heterogeneity, a random-effects model. A total of 2415 cases and 2011 controls were recruited in our investigation. A allele/GG genotype was not associated with CKD risk in overall populations, Asians, Caucasians, and Africans. AA/AG genotype was not associated with the risk of CKD in overall populations, Asians, Caucasians, and Africans. AA genotype was associated with a lower risk of CKD in Caucasians (OR 0.816, 95% CI 0.703-0.947). AG genotype was associated with a higher risk of CKD in Caucasians (OR 1.230, 95% CI 1.042-1.452). There was no marked publication bias. In conclusion, AA genotype may be a protective factor against CKD susceptibility in Caucasians. AG genotype may be a risk factor for CKD risk in Caucasians. However, more studies are needed in the future.

miR-374a Regulates Inflammatory Response in Diabetic Nephropathy by Targeting MCP-1 Expression

The microRNA (mir)-374a has been implicated in several types of human cancer; however, its role in diabetic nephropathy (DN) remains unclear. Monocyte chemoattractant protein (MCP)-1 is a chemokine that recruits macrophages to inflammatory sites and is important for the development and progression of DN. However, the relationship between miR-374a and MCP-1 in DN is unknown. We addressed this in the present study by examining the expression of these factors in kidney tissue samples from DN patients and through loss- and gain-of-function experiments using HK2 human renal tubular epithelial cells. We found that miR-374a was downregulated whereas MCP-1 was upregulated in DN tissue. A bioinformatics analysis revealed that MCP-1 is a putative target of miR-374a. To confirm this relationship, HK2 cells treated with normal glucose (5.6 mmol/l D-glucose), high glucose (HG) (30 mmol/l D-glucose), or high osmotic pressure solution (5.6 mmol/l D-glucose + 24.4 mmol/l D-mannitol) were transfected with miR-374a mimic or inhibitor. miR-374a mimic reduced MCP-1 mRNA expression and migration of co-cultured U937 cells, whereas miR-374a inhibition had the opposite effects. Additionally, interleukin-6 and -18 and tumor necrosis factor-α levels were downregulated by transfection of miR-374a mimic. On the other hand, MCP-1 overexpression reversed the inhibitory effects of miR-374a in HK2 cells. Thus, miR-374a suppresses the inflammatory response in DN through negative regulation of MCP-1 expression. These findings suggest that therapeutic strategies that target the miR-374a/MCP-1 axis can be an effective treatment for DN.

Effect of PF-04634817, an Oral CCR2/5 Chemokine Receptor Antagonist, on Albuminuria in Adults with Overt Diabetic Nephropathy

Introduction

Inflammatory cell recruitment, which is potentially mediated by the monocyte chemoattractant protein 1/C-C chemokine receptor type 2 (CCR2) system and by C-C chemokine receptor type 5 (CCR5) activity, may play a role in the development and progression of diabetic nephropathy. PF-04634817 is a dual chemokine CCR2/5 receptor antagonist that is being developed for the treatment of diabetic nephropathy.

Methods

We evaluated the efficacy of PF-04634817 compared with matching placebo for reduction of albuminuria after 12 weeks of treatment in subjects with type 2 diabetes who received standard of care (SOC; angiotensin-converting enzyme inhibitor or angiotensin receptor blocker therapy), in a randomized, double-blind, placebo-controlled, parallel-group phase 2 study.

Results

A total of 226 subjects who received SOC with baseline estimated glomerular filtration rates between 20 and 75 ml/min per 1.73 m² and a baseline urinary albumin-to-creatinine ratio (UACR) of ≥300 mg/g were randomly assigned 3:1 to receive PF-04634817 (150 or 200 mg orally, once daily) or placebo. The primary analysis was Bayesian, with an informative prior for placebo response (equivalent to including an additional 80 subjects in the placebo arm). We observed a placebo-adjusted reduction in UACR of 8.2% (ratio 0.918; 95% credible interval: 0.75–1.09) at week 12 in the PF-04634817 arm. PF-04634817 appeared to be safe and well-tolerated.

Conclusion

Despite the good safety profile shown by PF-04634817, clinical development for this indication was discontinued in light of the modest efficacy observed.

Early intervention with mesenchymal stem cells prevents nephropathy in diabetic rats by ameliorating the inflammatory microenvironment

Diabetic nephropathy (DN) is a major complication of diabetes and represents the leading cause of end-stage renal disease. Mesenchymal stem cell (MSC) treatment has been demonstrated to be effective in DN models by reducing albuminuria and attenuating glomerular injury; however, limited in-depth understanding of the underlying mechanism and a lack of clinical trials hinders its clinical use. Additionally, most of these experimental studies were conducted on the advanced stage of nephropathy, which is difficult to reverse and consequently showed limited therapeutic efficacy. We sought to evaluate whether early intervention by MSCs has the potential to prevent DN onset and progression as well as protect kidney function when intravenously administered to rats with diabetes. Diabetes was induced in adult male SD rats by streptozotocin (STZ) injection (55 mg/kg, i.p.). The diabetic rats were injected with or without bone marrow-derived MSCs (5×10⁶ per rat), via tail vein at 2, 4, 5 and 7 weeks after diabetes onset. Fasting blood glucose (FBG), blood urea nitrogen (BUN) and serum creatinine (Scr) levels in serum samples and glycosuria (GLU), microalbumin (MAU), and albumin to creatinine ratio (ACR) in urine samples were determined. Renal pathology and immunohistochemistry (IHC) for CD68, MCP-1, fibronectin (FN), transforming growth factor-β (TGF-β) and pro-inflammatory cytokines were also performed. Expression levels of the above factors as well as interleukin-10 (IL-10), and epidermal growth factor (EGF) were assessed by qPCR and multiplex bead-based suspension array system, respectively. Additionally, MSC tracing in vivo was performed. Ex vivo, peritoneal macrophages were co-cultured with MSCs, and expression of inflammatory cytokines was detected as well. MSC treatment profoundly suppressed renal macrophage infiltration and inflammatory cytokine secretion in diabetic rats, resulting in prominently improved kidney histology, systemic homeostasis, and animal survival, although no significant effect on hyperglycemia was observed. Engrafted MSCs were primarily localized in deteriorated areas of the kidney and immune organs 48 h after infusion. MSC treatment upregulated serum anti-inflammatory cytokines IL-10 and EGF. Ex vivo, MSCs inhibited lipopolysaccharide (LPS)-stimulated rat peritoneal macrophage activation via the downregulation of inflammatory-related cytokines such as IL-6, MCP-1, tumor necrosis factor-α (TNF-α) and IL-1β. Our results demonstrated that early intervention with MSCs prevented renal injury via immune regulation in diabetic rats, which restored the homeostasis of the immune microenvironment, contributing to the prevention of kidney dysfunction and glomerulosclerosis.