CCR2 antagonism improves insulin resistance, lipid metabolism, and diabetic nephropathy in type 2 diabetic mice

SGLT2 inhibitors and NLRP3 inflammasome: potential target in diabetic kidney disease

Diabetic kidney disease (DKD) remains the leading cause of chronic kidney disease (CKD) worldwide. The pathogenesis of DKD is influenced by functional, histopathological, and immune mechanisms, including NLRP3 inflammasome activity and oxidative stress. The sodium-glucose cotransporter 2 inhibitors (SGLT2i) have shown metabolic benefits and the ability to slow the progression of DKD in several clinical studies over the years. Recent studies suggest that the antidiabetic activity also extends to inhibition of the inflammatory response, including modulation of the NLRP3 inflammasome, reduction of pro-inflammatory markers and reduction of oxidative stress. Here we review the efficacy of SGLT2i in the treatment of CKD and discuss the role of the inflammatory response in the development of DKD, including its relationship to the NLRP3 inflammasome and oxidative stress.

Adipocyte-Specific Hnrnpa1 Knockout Aggravates Obesity-Induced Metabolic Dysfunction via Upregulation of CCL2

Heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1) is involved in lipid and glucose metabolism via mRNA processing. However, whether and how HNRNPA1 alters adipocyte function in obesity remain obscure. Here, we found that the obese state downregulated HNRNPA1 expression in white adipose tissue (WAT). The depletion of adipocyte HNRNPA1 promoted markedly increased macrophage infiltration and expression of proinflammatory and fibrosis genes in WAT of obese mice, eventually leading to exacerbated insulin sensitivity, glucose tolerance, and hepatic steatosis. Mechanistically, HNRNPA1 interacted with Ccl2 and regulated its mRNA stability. Intraperitoneal injection of CCL2-CCR2 signaling antagonist improved adipose tissue inflammation and systemic glucose homeostasis. Furthermore, HNRNPA1 expression in human WAT was negatively correlated with BMI, fat percentage, and subcutaneous fat area. Among individuals with 1-year metabolic surgery follow-up, HNRNPA1 expression was positively related to percentage of total weight loss. These findings identify adipocyte HNRNPA1 as a link between adipose tissue inflammation and systemic metabolic homeostasis, which might be a promising therapeutic target for obesity-related disorders.

ARTICLE HIGHLIGHTS

CCL2-CCR2 signaling axis in obesity and metabolic diseases

Obesity and metabolic diseases, such as insulin resistance, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular ailments, represent formidable global health challenges, bearing considerable implications for both morbidity and mortality rates. It has become increasingly evident that chronic, low-grade inflammation plays a pivotal role in the genesis and advancement of these conditions. The involvement of C-C chemokine ligand 2 (CCL2) and its corresponding receptor, C-C chemokine receptor 2 (CCR2), has been extensively documented in numerous inflammatory maladies. Recent evidence indicates that the CCL2/CCR2 pathway extends beyond immune cell recruitment and inflammation, exerting a notable influence on the genesis and progression of metabolic syndrome. The present review seeks to furnish a comprehensive exposition of the CCL2-CCR2 signaling axis within the context of obesity and metabolic disorders, elucidating its molecular mechanisms, functional roles, and therapeutic implications.

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.

The role of innate immunity in diabetic nephropathy and their therapeutic consequences

Diabetic nephropathy (DN) is an enduring condition that leads to inflammation and affects a substantial number of individuals with diabetes worldwide. A gradual reduction in glomerular filtration and emergence of proteins in the urine are typical aspects of DN, ultimately resulting in renal failure. Mounting evidence suggests that immunological and inflammatory factors are crucial for the development of DN. Therefore, the activation of innate immunity by resident renal and immune cells is critical for initiating and perpetuating inflammation. Toll-like receptors (TLRs) are an important group of receptors that identify patterns and activate immune responses and inflammation. Meanwhile, inflammatory responses in the liver, pancreatic islets, and kidneys involve inflammasomes and chemokines that generate pro-inflammatory cytokines. Moreover, the activation of the complement cascade can be triggered by glycated proteins. This review highlights recent findings elucidating how the innate immune system contributes to tissue fibrosis and organ dysfunction, ultimately leading to renal failure. This review also discusses innovative approaches that can be utilized to modulate the innate immune responses in DN for therapeutic purposes.

Myeloid PFKFB3-mediated glycolysis promotes kidney fibrosis

Excessive renal fibrosis is a common pathology in progressive chronic kidney diseases. Inflammatory injury and aberrant repair processes contribute to the development of kidney fibrosis. Myeloid cells, particularly monocytes/macrophages, play a crucial role in kidney fibrosis by releasing their proinflammatory cytokines and extracellular matrix components such as collagen and fibronectin into the microenvironment of the injured kidney. Numerous signaling pathways have been identified in relation to these activities. However, the involvement of metabolic pathways in myeloid cell functions during the development of renal fibrosis remains understudied. In our study, we initially reanalyzed single-cell RNA sequencing data of renal myeloid cells from Dr. Denby's group and observed an increased gene expression in glycolytic pathway in myeloid cells that are critical for renal inflammation and fibrosis. To investigate the role of myeloid glycolysis in renal fibrosis, we utilized a model of unilateral ureteral obstruction in mice deficient of Pfkfb3, an activator of glycolysis, in myeloid cells (Pfkfb3 ΔMϕ ) and their wild type littermates (Pfkfb3 WT). We observed a significant reduction in fibrosis in the obstructive kidneys of Pfkfb3 ΔMϕ mice compared to Pfkfb3 WT mice. This was accompanied by a substantial decrease in macrophage infiltration, as well as a decrease of M1 and M2 macrophages and a suppression of macrophage to obtain myofibroblast phenotype in the obstructive kidneys of Pfkfb3 ΔMϕ mice. Mechanistic studies indicate that glycolytic metabolites stabilize HIF1α, leading to alterations in macrophage phenotype that contribute to renal fibrosis. In conclusion, our study implicates that targeting myeloid glycolysis represents a novel approach to inhibit renal fibrosis.

Spexin-based galanin receptor 2 agonist improves renal injury in mice with type 2 diabetes

The spexin-based GALR2 agonist (NS200) is a novel drug, which has shown antidepressant and anxiolytic action in a recent experimental study. In this study, we investigated the effects of NS200 on renal injury in an animal model of type 2 diabetes. Eight-week-old diabetic db/db mice were administered NS200 for 12 weeks. NS200 was intraperitoneally administered at a dose of 1.0 mg/kg/day. Metabolic parameters and structural and molecular changes in the kidneys were compared among the three groups: non-diabetic db/m control, db/db mice, and NS200-treated db/db mice. In db/db mice, NS200 administration did not impact the body weight, food and water intake, urinary volume, fasting blood glucose level, or HbA1c levels. Insulin and glucose tolerance were also unaffected by NS200 treatment. However, NS200 improved urinary albumin excretion and glomerulosclerosis in diabetic kidneys. Activation of TGFβ1 and insulin signaling pathways, such as PI3 K /AKT/ERK, were inhibited by NS200. In conclusion, a spexin-based GALR2 agonist attenuated diabetic nephropathy by alleviating renal fibrosis in mice with type 2 diabetes. Spexin-based GALR2 agonists have considerable potential as novel treatment agents in diabetic nephropathy.

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

Background

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

Methods

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

Results

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

Conclusions

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

SERPINA5 may promote the development of preeclampsia by disruption of the uPA/uPAR pathway

Preeclampsia (PE) is the leading cause of maternal and fetal morbidity or mortality but lacks reliable methods for early diagnosis. In a previous study, serum SERPINA5 levels were higher in women with PE before the clinical manifestation of the disease. This study aimed to evaluate the efficacy of SERPINA5 in predicting PE and investigate its role in trophoblast cell biology. A multicenter, 2-stage observational case-control study was performed to develop and validate an early predictive PE model based on SERPINA5, maternal characteristics, and inflammatory factors. To further understand the relationship between SERPINA5 and PE, SERPINA5 was overexpressed or knocked down in extravillous trophoblast cells (EVT) and a pregnant rat model. After development and initial validation, a model that combined SERPINA5 and inflammatory factors had a high predictive ability for PE before 20 weeks gestation with an AUC of 0.90 (95% CI 0.83-0.96). It also demonstrated that SERPINA5 inhibited primary EVT cell invasion by disrupting the urokinase-type plasminogen activator/urokinase-type plasminogen activator receptor (uPA/uPAR) pathway, in turn, is involved in the development of PE. In vivo experiments also proved that overexpression of SERPINA5 induced a PE-like syndrome (hypertension and proteinuria) in pregnant rats. Therefore, serum SERPINA5 is a promising early biomarker of PE, suggesting that it may be involved in placental development through its action on the uPA/uPAR system prior to the clinical manifestation of PE.

Exploring the shared molecular mechanism of microvascular and macrovascular complications in diabetes: Seeking the hub of circulatory system injury

BACKGROUND

Microvascular complications, such as diabetic retinopathy (DR) and diabetic nephropathy (DN), and macrovascular complications, referring to atherosclerosis (AS), are the main complications of diabetes. Blindness or fatal microvascular diseases are considered to be identified earlier than fatal macrovascular complications. Exploring the intrinsic relationship between microvascular and macrovascular complications and the hub of pathogenesis is of vital importance for prolonging the life span of patients with diabetes and improving the quality of life.

MATERIALS AND METHODS

The expression profiles of GSE28829, GSE30529, GSE146615 and GSE134998 were downloaded from the Gene Expression Omnibus database, which contained 29 atherosclerotic plaque samples, including 16 AS samples and 13 normal controls; 22 renal glomeruli and tubules samples from diabetes nephropathy including 12 DN samples and 10 normal controls; 73 lymphoblastoid cell line samples, including 52 DR samples and 21 normal controls. The microarray datasets were consolidated and DEGs were acquired and further analyzed by bioinformatics techniques including GSEA analysis, GO-KEGG functional clustering by R (version 4.0.5), PPI analysis by Cytoscape (version 3.8.2) and String database, miRNA analysis by Diana database, and hub genes analysis by Metascape database. The drug sensitivity of characteristic DEGs was analyzed.

RESULT

A total of 3709, 4185 and 8086 DEGs were recognized in AS, DN, DR, respectively, with 1820, 1666, 888 upregulated and 1889, 2519, 7198 downregulated. GO and KEGG pathway analyses of DEGs and GSEA analysis of common differential genes demonstrated that these significant sites focused primarily on inflammation-oxidative stress and immune regulation pathways. PPI networks show the connection and regulation on top-250 significant sites of AS, DN, DR. MiRNA analysis explored the non-coding RNA upstream regulation network and significant pathway in AS, DN, DR. The joint analysis of multiple diseases shows the common influenced pathways of AS, DN, DR and explored the interaction between top-1000 DEGs at the same time.

CONCLUSION

In the microvascular and macrovascular complications of diabetes, immune-mediated inflammatory response, chronic inflammation caused by endothelial cell activation and oxidative stress are the three links linking atherosclerosis, diabetes retinopathy and diabetes nephropathy together. Our study has clarified the intrinsic relationship and common tissue damage mechanism of microcirculation and circulatory system complications in diabetes, and explored the mechanism center of these two vascular complications. It has far-reaching clinical and social value for reducing the incidence of fatal events and early controlling the progress of disabling and fatal circulatory complications in diabetes.

T cells and their products in diabetic kidney disease

Diabetic kidney disease (DKD) is the most common cause of end-stage renal disease and has gradually become a public health problem worldwide. DKD is increasingly recognized as a comprehensive inflammatory disease that is largely regulated by T cells. Given the pivotal role of T cells and T cells-producing cytokines in DKD, we summarized recent advances concerning T cells in the progression of type 2 diabetic nephropathy and provided a novel perspective of immune-related factors in diabetes. Specific emphasis is placed on the classification of T cells, process of T cell recruitment, function of T cells in the development of diabetic kidney damage, and potential treatments and therapeutic strategies involving T cells.

Transcriptional profile changes after treatment of ischemia reperfusion injury-induced kidney fibrosis with 18β-glycyrrhetinic acid

Introduction

Chronic kidney disease (CKD) is characterized by renal fibrosis without effective therapy. 18β-Glycyrrhetinic acid (GA) is reported to have detoxification and anti-inflammatory functions and promotes tissue repair. However, the role of GA in CKD remains unclear. In this study, we investigated whether GA has a potential therapeutic effect in kidney fibrosis.

Methods

A renal fibrosis mouse model was established by ischemia/reperfusion (I/R) injury via clamping unilateral left renal pedicle for 45 min; then, the mice were treated with vehicle or GA. Kidney tissues and blood samples were extracted 14 days after reperfusion and renal function, histopathological staining, quantitative PCR, and western blotting were performed. RNA-seq was performed to explore the changes in the transcriptional profile after GA treatment.

Results

Renal function, pathological and molecular analysis displayed that fibrosis was successfully induced in the I/R model. In the GA treatment group, the severity of fibrosis gradually reduced with the best effect seen at a concentration of 25 mg kg ⁻¹. A total of 970 differentially expressed genes were identified. Pathway enrichment showed that reduced activation and migration of inflammatory cells and decreased chemokine interaction in significant pathways. Protein–protein interaction networks were constructed and 15 hub genes were selected by degree rank, including chemokines, such as C3, Ccl6, Ccr2, Ptafr, Timp1, and Pf4.

Conclusions

GA may alleviate renal fibrosis by inhibiting the inflammatory response. GA is a promising therapy that may perhaps be used in treating renal fibrosis and CKD.

Roles and crosstalks of macrophages in diabetic nephropathy

Diabetic nephropathy (DN) is the most common chronic kidney disease. Accumulation of glucose and metabolites activates resident macrophages in kidneys. Resident macrophages play diverse roles on diabetic kidney injuries by releasing cytokines/chemokines, recruiting peripheral monocytes/macrophages, enhancing renal cell injuries (podocytes, mesangial cells, endothelial cells and tubular epithelial cells), and macrophage-myofibroblast transition. The differentiation and cross-talks of macrophages ultimately result renal inflammation and fibrosis in DN. Emerging evidence shows that targeting macrophages by suppressing macrophage activation/transition, and macrophages-cell interactions may be a promising approach to attenuate DN. In the review, we summarized the diverse roles of macrophages and the cross-talks to other cells in DN, and highlighted the therapeutic potentials by targeting macrophages.

Therapeutic CCR2 Blockade Prevents Inflammation and Alleviates Myxomatous Valve Disease in Marfan Syndrome

Myxomatous valve disease (MVD) can lead to cardiac dysfunction and heart failure, yet medical therapies are lacking. C-C chemokine receptor type 2 (CCR2)+ immune cell infiltration promotes mitral valve inflammation in a Marfan syndrome (MFS) mouse model. The CCR2 genetic knockout reduces inflammation with downregulated proteases and improved extracellular matrix integrity. Pharmacological inhibition of CCR2+ cell infiltration by RS504393 prevents the initiation and progression of MVD, indicated by restored protease expression, improved extracellular matrix organization, and reduced valve leaflet thickness in MFS mice. Thus, the CCR2 antagonist RS504393 is a promising therapy for the treatment of MVD in MFS.

The Roles of Adipose Tissue Macrophages in Human Disease

Macrophages are a population of immune cells functioning in antigen presentation and inflammatory response. Research has demonstrated that macrophages belong to a cell lineage with strong plasticity and heterogeneity and can be polarized into different phenotypes under different microenvironments or stimuli. Many macrophages can be recruited by various cytokines secreted by adipose tissue. The recruited macrophages further secrete various inflammatory factors to act on adipocytes, and the interaction between the two leads to chronic inflammation. Previous studies have indicated that adipose tissue macrophages (ATMs) are closely related to metabolic diseases like obesity and diabetes. Here, we will not only conclude the current progress of factors affecting the polarization of adipose tissue macrophages but also elucidate the relationship between ATMs and human diseases. Furthermore, we will highlight its potential in preventing and treating metabolic diseases as immunotherapy targets.

Diabetic kidney disease-predisposing proinflammatory and profibrotic genes identified by weighted gene co-expression network analysis (WGCNA)

Diabetic kidney disease (DKD) is one of the most serious microvascular complications of diabetes. Despite enormous efforts, the underlying underpinnings of DKD remain incompletely appreciated. We sought to perform novel and informative bioinformatic analysis to explore the molecular mechanism of DKD. The gene expression profiles of GSE142025, GSE30528, and GSE30529 datasets were downloaded from the Gene Expression Omnibus database. After the GSE142025 data set was preprocessed, a gene co-expression network was constructed by weighted gene co-expression network analysis (WGCNA), and hub genes were selected in the key modules. Meanwhile, differentially expressed genes (DEGs) upregulated commonly were identified between the GSE30528 and GSE30529 datasets. Then, pathway and process enrichment analysis were performed for hub genes and commonly upregulated DEGs. Next, candidate targets were identified by comparing hub genes to commonly upregulated DEGs. Finally, reverse-transcription quantitative polymerase chain reaction (RT-qPCR) was carried out to validate the expression of candidate targets, and protein-protein interaction (PPI) network was constructed. A total of 17 modules were clustered by WGCNA, and the most significant turquoise module was selected. Based upon MM > 0.7 and GM > 0.7, 313 hub genes were screened out in turquoise module. Functional analysis of these 313 genes demonstrated their enrichment in pathways involved in leukocyte differentiation, cell morphogenesis, lymphocyte activation, vascular development, collagen synthesis, chemotaxis, and chemokine signaling. A total of 115 commonly upregulated DEGs were identified between the GSE30528 and GSE30529 datasets. Intriguingly, a total of six proinflammatory and profibrotic candidate targets were selected and validated in DKD mice in vivo, including CCR2, MOXD1, COL6A3, COL1A2, PYCARD, and C7. Based on WGCNA and DEG analysis of DKD datasets, six DKD-predisposing candidate targets were uncovered. The data suggest that inflammation and fibrosis are key mechanisms of DKD, and future studies may determine the causal link between the six proinflammatory and profibrotic genes and DKD.

Effects of tumor necrosis factor-α inhibition on kidney fibrosis and inflammation in a mouse model of aristolochic acid nephropathy

Tumor necrosis factor (TNF)-α is a potent mediator of inflammation and is involved in the pathophysiology of chronic kidney disease (CKD). However, the effects of TNF-α inhibition on the progression of kidney fibrosis have not been fully elucidated. We examined the effects of TNF-α inhibition by etanercept (ETN) on kidney inflammation and fibrosis in mice with aristolochic acid (AA) nephropathy as a model of kidney fibrosis. C57BL/6 J mice were administered AA for 4 weeks, followed by a 4-week remodeling period. The mice exhibited kidney fibrosis, functional decline, and albuminuria concomitant with increases in renal mRNA expression of inflammation- and fibrosis-related genes. The 8-week ETN treatment partially but significantly attenuated kidney fibrosis and ameliorated albuminuria without affecting kidney function. These findings were accompanied by significant suppression of interleukin (IL)-1β, IL-6, and collagen types I and III mRNA expression. Moreover, ETN tended to reduce the AA-induced increase in interstitial TUNEL-positive cells with a significant reduction in Bax mRNA expression. Renal phosphorylated p38 MAPK was significantly upregulated by AA but was normalized by ETN. These findings indicate a substantial role for the TNF-α pathway in the pathogenesis of kidney fibrosis and suggest that TNF-α inhibition could become an adjunct therapeutic strategy for CKD with fibrosis.

Effects of a CCR2 antagonist on macrophages and Toll-like receptor 9 expression in a mouse model of diabetic nephropathy

The pathogenesis of diabetic nephropathy (DN) is related to macrophage (Mφ) recruitment to the kidneys, tumor necrosis factor-α (TNF-α) production, and oxidative stress. Toll-like receptor 9 (TLR9) activation is reportedly involved in systemic inflammation, and it exacerbates this condition in metabolic syndrome. Therefore, we hypothesized that TLR9 plays a role in the pathogenesis of DN. Two subsets of kidney Mφs in DN model (db/db) mice were analyzed using flow cytometry to evaluate their distribution and TLR9 expression and function. Mice were administered the CCR2 antagonist INCB3344 for 8 wk; changes in Mφ distribution and function and its therapeutic effects on DN pathology were examined. Bone marrow-derived CD11bhigh (BM-Mφ) and tissue-resident CD11blow Mφs (Res-Mφ) were identified in the mouse kidneys. As DN progressed, the BM-Mφ number, TLR9 expression, and TNF-α production increased significantly. In Res-Mφs, reactive oxygen species (ROS) production and phagocytic activity were enhanced. INCB3344 decreased albuminuria, serum creatinine level, BM-Mφ abundance, TLR9 expression, and TNF-α production by BM-Mφs and ROS production by Res-Mφs. Both increased activation of BM-Mφ via TLR9 and TNF-α production and increased ROS production by Res-Mφs were involved in DN progression. Thus, inactivating Mφs and their TLR9 expression by INCB3344 is a potential therapeutic strategy for DN.NEW & NOTEWORTHY We classified kidney macrophages (Mφs) into bone marrow-derived Mφs (BM-Mφs) expressing high CD11b and tissue-specific resident Mφ (Res-Mφs) expressing low CD11b. In diabetic nephropathy (DN) model mice, Toll-like receptor 9 (TLR9) expression and TNF-α production via TLR9 activation in BM-Mφs and ROS production in Res-Mφs were enhanced. Furthermore, CCR2 antagonist suppressed the kidney infiltration of BM-Mφs and their function and the ROS production by Res-Mφs, with concomitant TLR9 suppression. Our study presents a new therapeutic strategy for DN.

Effects of soy isoflavone supplementation on patients with diabetic nephropathy: a systematic review and meta-analysis of randomized controlled trials

Diabetic nephropathy (DN) is a microvascular complication that is becoming a worldwide public health concern. The aim of this study was to assess the effects of dietary soy isoflavone intervention on renal function and metabolic syndrome markers in DN patients. Seven databases including Medline, the Cochrane Central Register of Controlled Trials, Science Direct, Web of Science, Embase, China National Knowledge Infrastructure, and WanFang were searched for controlled trials that assessed the effects of soy isoflavone treatment in DN patients. Finally, a total of 141 patients from 7 randomized controlled trials were included. The meta-analysis showed that dietary soy isoflavones significantly decreased 24-hour urine protein, C-reactive protein (CRP), blood urea nitrogen (BUN), total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and fasting blood glucose (FBG) in DN patients. The standard mean difference was -2.58 (95% CI: -3.94, -1.22; P = 0.0002) for 24-hour urine protein, -0.67 (95% CI: -0.94, -0.41; P < 0.00001) for BUN, -6.16 (95% CI: -9.02, -3.31; P < 0.0001) for CRP, -0.58 (95% CI: -0.83, -0.33; P < 0.00001) for TC, -0.41 (95% CI: -0.66, -0.16; P < 0.00001) for TG, -0.68 (95% CI: -0.94, -0.42; P < 0.00001) for LDL-C, and -0.39 (95% CI: -0.68, -0.10; P = 0.008) for FBG. Therefore, soy isoflavones may ameliorate DN by significantly decreasing 24-hour urine protein, BUN, CRP, TC, TG, LDL-C, and FBG.

Analysis of long non-coding RNAs in skeletal muscle of Bama Xiang pigs in response to heat stress

The aim of this study was to identify differentially expressed long non-coding RNAs (lncRNAs) molecules and predict their target genes related to muscle development and lipid metabolism in longissimus dorsi (LD) muscles of Bama Xiang pigs under constant heat stress. Ten male Bama Xiang pigs with an average initial body weight of 14 kg were randomly divided into control group (22°C) and heat stress (35 °C) group. The experiment lasted for 28 days. All the pigs were slaughtered at the end of the experiment, and LD muscles were collected for muscle quality analysis and transcriptome sequencing. Heat stress reduced meat quality of Bama Xiang pigs. lncRNAs in LD were identified systematically by deep RNA sequencing between the two groups. The results showed that 365 lncRNAs from the LD were identified, including 128 intergenic lncRNAs, 82 intronic lncRNAs, and 155 anti-sense lncRNAs. The differences lie in transcript of length, number of exons and wider size distribution, and expression level per KB fragment in three subtypes of lncRNAs. The three types of transposable elements coverage, including Line/L1, SINE/tRNA, and LTR/ERVL-MaLR, are the highest in mRNA and the three subtypes of lncRNAs in pigs. lncRNAs and mRNAs were different in comparison of features. The results predicted the target genes of the significant differentially expressed lncRNAs related to muscle development and lipid metabolism. This is the first study to expand the knowledge about muscle-related lncRNAs biology in Bama Xiang pigs under heat stress and will contribute to the development of alleviating the adverse effects of heat stress on pork quality targeting lncRNAs.

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.

Design and Characterization of an Intracellular Covalent Ligand for CC Chemokine Receptor 2

Covalently acting inhibitors constitute a large and growing fraction of approved small-molecule therapeutics as well as useful tools for a variety of in vitro and in vivo applications. Here, we aimed to develop a covalent antagonist of CC chemokine receptor 2 (CCR2), a class A GPCR that has been pursued as a therapeutic target in inflammation and immuno-oncology. Based on a known intracellularly binding CCR2 antagonist, several covalent derivatives were synthesized and characterized by radioligand binding and functional assays. These studies revealed compound 14 as an intracellular covalent ligand for CCR2. In silico modeling followed by site-directed mutagenesis confirmed that 14 forms a covalent bond with one of three proximal cysteine residues, which can be engaged interchangeably. To our knowledge, compound 14 represents the first covalent ligand reported for CCR2. Due to its unique properties, it may represent a promising tool for ongoing and future studies of CCR2 pharmacology.

Recent advances targeting C-C chemokine receptor type 2 for liver diseases in monocyte/macrophage

Liver plays a critical role in metabolism, nutrient storage and detoxification. Emergency signals or appropriate immune response leads to pathological inflammation and breaks the steady state when liver dysfunction appears, which makes body more susceptible to chronic liver infection, autoimmune diseases and tumour. Compelling proof has illustrated the non-redundant importance of C-C chemokine receptor type 2 (CCR2), one of G-protein-coupled receptors, in different diseases. Selectively expressed on the surface of cells, CCR2 is involved in various signalling pathways and regulates the migration of cells. Especially, a peculiar role of CCR2 has been identified within decades in the onset and progression of hepatic diseases, which led to particular focusing on CCR2 as a new therapeutic and diagnostic target for non-alcoholic fatty liver disease and hepatocellular carcinoma. In this review, we discuss the effect of CCR2 in monocytes/macrophages on liver diseases. The application and translation of the decades of discoveries into therapies promise novel approaches in the treatment of liver disease.

Xiaokeyinshui extract combination, a berberine-containing agent, exerts anti-diabetic and renal protective effects on rats in multi-target mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaokeyinshui (XKYS) formula, an anti-diabetic formula, was recorded in many ancient Chinese medical books. Xiaokeyinshui extract combination (XEC) originated from this ancient formula, consisting extracts of four herbal drugs, namely, Coptidis Rhizoma, Liriopes Radix, bitter melon, and Cassiae Semen.

OBJECTIVE

Therapeutic effects of Xiaokeyinshui extract combination (XEC) were assessed on diabetic rats.

MATERIALS AND METHODS

Herb extracts were prepared and mixed, yielding XEC. XEC were intragastrically given at doses of 260, 380 and 500 mg/kg/d to diabetic rats for 60 days. Anti-diabetic effects of XEC were studied, with measurement of body weight, and assessment of both glycemic control and lipid management. Measurement of oxidative stress and inflammatory cytokines were conducted in accordance to protocols of commercial kits. Parameters related to renal functions were also measured. Western blot (WB) analysis was performed to explore the anti-diabetic and renal protective mechanisms of XEC.

RESULTS

Compared to diabetic control, XEC exhibited significant effects in both glucose-lowering and lipid management (p < 0.01). Both oxidative stress and inflammatory cytokines were reduced after treatment of XEC for two months. In addition, XEC exhibited renal protective effects. WB analysis of liver tissue demonstrated that XEC achieved anti-diabetic effects through up-regulation of InsRα/IRS-1/PI3K/Akt/GLUT4 signaling pathway and phosphorylation of AMPK. In addition, renal protective effects were also achieved with down-regulation of RAGE and VEGF expressions in kidney.

CONCLUSIONS

XEC exerts promising anti-diabetic and renal protective effects on diabetic rats in multi-target mechanisms. XEC could be a satisfying alternative treating T2DM and preventing diabetic nephropathy.

Sulforaphane prevents type 2 diabetes-induced nephropathy via AMPK-mediated activation of lipid metabolic pathways and Nrf2 antioxidative function

Sulforaphane (SFN) prevents diabetic nephropathy (DN) in type 2 diabetes (T2D) by up-regulating nuclear factor (erythroid-derived 2)-like 2 (Nrf2). AMP-activated protein kinase (AMPK) can attenuate the pathogenesis of DN by improving renal lipotoxicity along with the activation of Nrf2-mediated antioxidative signaling. Therefore, we investigated whether AMPKα2, the central subunit of AMPK in energy metabolism, is required for SFN protection against DN in T2D, and whether potential cross-talk occurs between AMPKα2 and Nrf2. AMPKα2 knockout (Ampkα2-/-) mice and wildtype (WT) mice were fed a high-fat diet (HFD) or a normal diet (ND) to induce insulin resistance, followed by streptozotocin (STZ) injection to induce hyperglycemia, as a T2D model. Both T2D and control mice were treated with SFN or vehicle for 3 months. At the end of the 3-month treatment, all mice were maintained only on HFD or ND for an additional 3 months without SFN treatment. Mice were killed at sixth month after T2D onset. Twenty-four-hour urine albumin at third and sixth months was significantly increased as renal dysfunction, along with significant renal pathological changes and biochemical changes including renal hypertrophy, oxidative damage, inflammation, and fibrosis in WT T2D mice, which were prevented by SFN in certain contexts, but not in Ampkα2-/- T2D mice. SFN prevention of T2D-induced renal lipotoxicity was associated with AMPK-mediated activation of lipid metabolism and Nrf2-dependent antioxidative function in WT mice, but not in SFN-treated Ampkα2-/- mice. Therefore, SFN prevention of DN is AMPKα2-mediated activation of probably both lipid metabolism and Nrf2 via AMPK/AKT/glycogen synthase kinase (GSK)-3β/Src family tyrosine kinase (Fyn) pathways.

Correlation of host inflammatory cytokines and immune-related metabolites, but not viral NS1 protein, with disease severity of dengue virus infection

Severe dengue can be lethal caused by manifestations such as severe bleeding, fluid accumulation and organ impairment. This study aimed to investigate the role of dengue non-structural 1 (NS1) protein and host factors contributing to severe dengue. Electrical cell-substrate impedance sensing system was used to investigate the changes in barrier function of microvascular endothelial cells treated NS1 protein and serum samples from patients with different disease severity. Cytokines and metabolites profiles were assessed using a multiplex cytokine assay and liquid chromatography mass spectrometry respectively. The findings showed that NS1 was able to induce the loss of barrier function in microvascular endothelium in a dose dependent manner, however, the level of NS1 in serum samples did not correlate with the extent of vascular leakage induced. Further assessment of host factors revealed that cytokines such as CCL2, CCL5, CCL20 and CXCL1, as well as adhesion molecule ICAM-1, that are involved in leukocytes infiltration were expressed higher in dengue patients in comparison to healthy individuals. In addition, metabolomics study revealed the presence of deregulated metabolites involved in the phospholipid metabolism pathway in patients with severe manifestations. In conclusion, disease severity in dengue virus infection did not correlate directly with NS1 level, but instead with host factors that are involved in the regulation of junctional integrity and phospholipid metabolism. However, as the studied population was relatively small in this study, these exploratory findings should be confirmed by expanding the sample size using an independent cohort to further establish the significance of this study.

Propagermanium administration for patients with type 2 diabetes and nephropathy: A randomized pilot trial

AIMS

We assessed the potential efficacy and safety of propagermanium (PG), an organic compound that inhibits the C-C chemokine receptor type 2, administration in patients with type 2 diabetes and nephropathy. Furthermore, we assessed the feasibility of future studies.

MATERIALS AND METHODS

We recruited patients from nine medical institutions in Japan for this randomized, open-label, parallel two-arm pilot trial. Inclusion criteria were diagnosis of type 2 diabetes, age 30-75 years, dipstick proteinuria of ≥1+ or urinary albumin-to-creatinine ratio (UACR) of ≥30 mg/g and estimated glomerular filtration rate of ≥30 mL/min/1.73 m2. Patients were randomly assigned (1:2) using a minimization algorithm to either continuing usual care or concomitant administration of 30 mg PG per day for 12 months. The primary outcome was the change in UACR from baseline to 12 months. We also collected safety information for all patients who received at least one dose of PG.

RESULTS

We enrolled 29 patients, 10 were assigned to continue usual care and 19 to receive PG. Changes in UACR by PG in addition to the usual care were 25.0% (95% CI -20.4%, 96.5%, P = .33). No severe adverse events or renal events were observed during the study.

CONCLUSION

Although the treatment with PG was generally well tolerated, the dosage of 30 mg/d for 12 months did not reduce albuminuria when used in addition to usual care in patients with type 2 diabetes and nephropathy. Efficacy of PG should be verified in future definitive trials.

Altered adipose tissue and adipocyte function in the pathogenesis of metabolic syndrome

Over the past decade, great progress has been made in understanding the complexity of adipose tissue biology and its role in metabolism. This includes new insights into the multiple layers of adipose tissue heterogeneity, not only differences between white and brown adipocytes, but also differences in white adipose tissue at the depot level and even heterogeneity of white adipocytes within a single depot. These inter- and intra-depot differences in adipocytes are developmentally programmed and contribute to the wide range of effects observed in disorders with fat excess (overweight/obesity) or fat loss (lipodystrophy). Recent studies also highlight the underappreciated dynamic nature of adipose tissue, including potential to undergo rapid turnover and dedifferentiation and as a source of stem cells. Finally, we explore the rapidly expanding field of adipose tissue as an endocrine organ, and how adipose tissue communicates with other tissues to regulate systemic metabolism both centrally and peripherally through secretion of adipocyte-derived peptide hormones, inflammatory mediators, signaling lipids, and miRNAs packaged in exosomes. Together these attributes and complexities create a robust, multidimensional signaling network that is central to metabolic homeostasis.

Pathogenic Pathways and Therapeutic Approaches Targeting Inflammation in Diabetic Nephropathy

Diabetic nephropathy (DN) is associated with an increased morbidity and mortality, resulting in elevated cost for public health systems. DN is the main cause of chronic kidney disease (CKD) and its incidence increases the number of patients that develop the end-stage renal disease (ESRD). There are growing epidemiological and preclinical evidence about the close relationship between inflammatory response and the occurrence and progression of DN. Several anti-inflammatory strategies targeting specific inflammatory mediators (cell adhesion molecules, chemokines and cytokines) and intracellular signaling pathways have shown beneficial effects in experimental models of DN, decreasing proteinuria and renal lesions. A number of inflammatory molecules have been shown useful to identify diabetic patients at high risk of developing renal complications. In this review, we focus on the key role of inflammation in the genesis and progression of DN, with a special interest in effector molecules and activated intracellular pathways leading to renal damage, as well as a comprehensive update of new therapeutic strategies targeting inflammation to prevent and/or retard renal injury.

Lipotoxicity and Diabetic Nephropathy: Novel Mechanistic Insights and Therapeutic Opportunities

Lipotoxicity is characterized by the ectopic accumulation of lipids in organs different from adipose tissue. Lipotoxicity is mainly associated with dysfunctional signaling and insulin resistance response in non-adipose tissue such as myocardium, pancreas, skeletal muscle, liver, and kidney. Serum lipid abnormalities and renal ectopic lipid accumulation have been associated with the development of kidney diseases, in particular diabetic nephropathy. Chronic hyperinsulinemia, often seen in type 2 diabetes, plays a crucial role in blood and liver lipid metabolism abnormalities, thus resulting in increased non-esterified fatty acids (NEFA). Excessive lipid accumulation alters cellular homeostasis and activates lipogenic and glycogenic cell-signaling pathways. Recent evidences indicate that both quantity and quality of lipids are involved in renal damage associated to lipotoxicity by activating inflammation, oxidative stress, mitochondrial dysfunction, and cell-death. The pathological effects of lipotoxicity have been observed in renal cells, thus promoting podocyte injury, tubular damage, mesangial proliferation, endothelial activation, and formation of macrophage-derived foam cells. Therefore, this review examines the recent preclinical and clinical research about the potentially harmful effects of lipids in the kidney, metabolic markers associated with these mechanisms, major signaling pathways affected, the causes of excessive lipid accumulation, and the types of lipids involved, as well as offers a comprehensive update of therapeutic strategies targeting lipotoxicity.

Panax Notoginseng Ameliorates Podocyte EMT by Targeting the Wnt/β-Catenin Signaling Pathway in STZ-Induced Diabetic Rats

Introduction

Epithelial–mesenchymal transition (EMT) may contribute to podocyte dysfunction in diabetic nephropathy (DN). Aiming to identify novel therapeutic options, we investigated the protective effects of Panax notoginseng (PN) on podocyte EMT in diabetic rats and explored its mechanisms.

Methods

Diabetes was induced in rats with streptozotocin (STZ) by intraperitoneal injection at 55 mg/kg. Diabetic rats were randomly divided into three groups, namely, diabetic rats, diabetic rats treated with beraprost sodium (BPS) at 0.6 mg/kg/d or PN at 0.4 g/kg/d p.o., for 12 weeks. Urinary albumin/creatinine ratio (ACR), biochemical parameters, renal histopathology, and podocyte morphological changes were evaluated. Protein expression of EMT markers (desmin, α-SMA, and nephrin) as well as components of the Wnt/β-catenin pathway (wnt1, β-catenin, and snail) was detected by immunohistochemistry and Western blot, respectively.

Results

In diabetic rats, severe hyperglycemia and albuminuria were detected. Moreover, mesangial expansion and podocyte foot process effacement were found markedly increased in diabetic kidneys. Increased protein expression of wnt1, β-catenin, snail, desmin, and α-SMA, as well as decreased protein expression of nephrin was detected in diabetic kidneys. All these abnormalities found in DN rats were partially restored by PN treatment.

Conclusion

PN ameliorated albuminuria and podocyte EMT in diabetic rats partly through inhibiting Wnt/β-catenin signaling pathway. These findings provide experimental arguments for a novel therapeutic option in DN.

Innate immunity in diabetic kidney disease

Increasing evidence suggests that renal inflammation contributes to the pathogenesis and progression of diabetic kidney disease (DKD) and that anti-inflammatory therapies might have renoprotective effects in DKD. Immune cells and resident renal cells that activate innate immunity have critical roles in triggering and sustaining inflammation in this setting. Evidence from clinical and experimental studies suggests that several innate immune pathways have potential roles in the pathogenesis and progression of DKD. Toll-like receptors detect endogenous danger-associated molecular patterns generated during diabetes and induce a sterile tubulointerstitial inflammatory response via the NF-κB signalling pathway. The NLRP3 inflammasome links sensing of metabolic stress in the diabetic kidney to activation of pro-inflammatory cascades via the induction of IL-1β and IL-18. The kallikrein-kinin system promotes inflammatory processes via the generation of bradykinins and the activation of bradykinin receptors, and activation of protease-activated receptors on kidney cells by coagulation enzymes contributes to renal inflammation and fibrosis in DKD. In addition, hyperglycaemia leads to protein glycation and activation of the complement cascade via recognition of glycated proteins by mannan-binding lectin and/or dysfunction of glycated complement regulatory proteins. Data from preclinical studies suggest that targeting these innate immune pathways could lead to novel therapies for DKD.

Treatment with adipose tissue-derived mesenchymal stem cells exerts anti-diabetic effects, improves long-term complications, and attenuates inflammation in type 2 diabetic rats

Background

Long-term diabetes-associated complications are the major causes of morbidity and mortality in individuals with diabetes. These diabetic complications are closely linked to immune system activation along with chronic, non-resolving inflammation, but therapies to directly reverse these complications are still not available. Our previous study demonstrated that mesenchymal stem cells (MSCs) attenuated chronic inflammation in type 2 diabetes mellitus (T2DM), resulting in improved insulin sensitivity and islet function. Therefore, we speculated that MSCs might exert anti-inflammatory effects and promote the reversal of diabetes-induced kidney, liver, lung, heart, and lens diseases in T2DM rats.

Methods

We induced a long-term T2DM complication rat model by using a combination of a low dose of streptozotocin (STZ) with a high-fat diet (HFD) for 32 weeks. Adipose-derived mesenchymal stem cells (ADSCs) were systemically administered once a week for 24 weeks. Then, we investigated the role of ADSCs in modulating the progress of long-term diabetic complications.

Results

Multiple infusions of ADSCs attenuated chronic kidney disease (CKD), nonalcoholic steatohepatitis (NASH), lung fibrosis, and cataracts; improved cardiac function; and lowered serum lipid levels in T2DM rats. Moreover, the levels of inflammatory cytokines in the serum of each animal group revealed that ADSC infusions were able to not only inhibit pro-inflammatory cytokines IL-6, IL-1β, and TNF-α expression but also increase anti-inflammatory cytokine IL-10 systematically. Additionally, MSCs reduced the number of iNOS(+) M1 macrophages and restored the number of CD163(+) M2 macrophages.

Conclusions

Multiple intravenous infusions of ADSCs produced significant protective effects against long-term T2DM complications by alleviating inflammation and promoting tissue repair. The present study suggests ADSCs may be a novel, alternative cell therapy for long-term diabetic complications.

Macrophage ontogeny in the control of adipose tissue biology

Macrophages are found in large numbers in the adipose tissue where they closely associate with the adipocytes and the vasculature. Adipose tissue macrophages are a heterogenous population of cells with 'hard wired' diversity brought upon by distinct developmental lineages. The purpose of this review is to provide a brief history of macrophages in control of adipose tissue metabolism with the emphasis on the importance of macrophage ontogeny.

Combined inhibition of CCR2 and ACE provides added protection against progression of diabetic nephropathy in Nos3-deficient mice

Macrophage-mediated renal injury promotes the development of diabetic nephropathy. Blockade of chemokine (C-C motif) receptor 2 (CCR2) inhibits kidney macrophage accumulation and early glomerular damage in diabetic animals. This study tested early and late interventions with a CCR2 antagonist (CCR2A) in a model of progressive diabetic glomerulosclerosis and determined whether CCR2A provides added benefit over conventional treatment with an angiotensin-converting enzyme inhibitor (ACEi). Diabetes was induced in hypertensive endothelial nitric oxide synthase (Nos3)-deficient mice by administration of five low-dose streptozotocin (STZ) injections daily. Groups of diabetic Nos3^-/- mice received a CCR2A (30 mg·kg^-1·day^-1 PF-04634817 in chow) as an early intervention (weeks 2-15 after STZ). The late intervention (weeks 8-15 after STZ) involved PF-04634817 alone, ACEi (captopril in water 10 mg·kg^-1·day^-1) alone, or combined ACEi + CCR2A. Control diabetic and nondiabetic Nos3^-/- mice received normal chow and water. Early intervention with a CCR2A inhibited kidney inflammation and glomerulosclerosis, albuminuria, podocyte loss, and renal function impairment but not hypertension in diabetic Nos3^-/- mice. Late intervention with a CCR2A also inhibited kidney inflammation, glomerulosclerosis, and renal dysfunction but did not affect albuminuria. ACEi alone suppressed hypertension and albuminuria and partially reduced podocyte loss and glomerulosclerosis but did not affect renal dysfunction. Compared with ACEi alone, the combined late intervention with ACEi + CCR2A provided better protection against kidney damage (inflammation, glomerulosclerosis, and renal function impairment) but not albuminuria. In conclusion, this study demonstrates that combining CCR2A and ACEi provides broader and superior renal protection than ACEi alone in a model of established diabetic glomerulosclerosis with hypertension.

CCR2 knockout ameliorates obesity-induced kidney injury through inhibiting oxidative stress and ER stress

CCL2/CCR2 signaling is believed to play an important role in kidney diseases. Several studies have demonstrated that blocking of CCR2 has a therapeutic effect on kidney diseases. However, the effects of CCR2 knockout on obesity-induced kidney injury remain unclear. We investigated the therapeutic effects and the mechanism of CCL2/CCR2 signaling in obesity-induced kidney injury. We used C57BL/6-CCR2 wild type and C57BL/6-CCR2 knockout mice: Regular diet wild type (RD WT), RD CCR2 knockout (RD KO), High-fat diet WT (HFD WT), HFD CCR2 KO (HFD KO). Body weight of WT mice was significantly increased after HFD. However, the body weight of HFD KO mice was not decreased compared to HFD WT mice. Food intake and calorie showed no significant differences between HFD WT and HFD KO mice. Glucose, insulin, total cholesterol, and triglycerides levels increased in HFD WT mice were decreased in HFD KO mice. Insulin resistance, increased insulin secretion, and lipid accumulation showed in HFD WT mice were improved in HFD KO mice. Increased desmin expression, macrophage infiltration, and TNF-α in HFD mice were reduced in HFD KO mice. HFD-induced albuminuria, glomerular hypertrophy, glomerular basement membrane thickening, and podocyte effacement were restored by CCR2 depletion. HFD-induced elevated expressions of xBP1, Bip, and Nox4 at RNA and protein levels were significantly decreased in HFD KO. Therefore, blockade of CCL2/CCR2 signaling by CCR2 depletion might ameliorate obesity-induced albuminuria through blocking oxidative stress, ER stress, and lipid accumulation.

PTPN2 improved renal injury and fibrosis by suppressing STAT-induced inflammation in early diabetic nephropathy

Diabetic nephropathy (DN) is a chronic inflammatory disease triggered by disordered metabolism. Recent studies suggested that protein tyrosine phosphatase non‐receptor type 2 (PTPN2) could ameliorate metabolic disorders and suppress inflammatory responses. This study investigated PTPN2's role in modulating DN and the possible cellular mechanisms involved. In a mouse model combining hyperglycaemia and hypercholesterolaemia (streptozotocin diabetic, ApoE^‐/‐ mice), mice showed severe insulin resistance, renal dysfunction, micro‐inflammation, subsequent extracellular matrix expansion and decreased expression of PTPN2. We found that mice treated with PTPN2 displayed reduced serum creatinine, serum BUN and proteinuria. PTPN2 gene therapy markedly attenuated metabolic disorders and hyperglycaemia. In addition, PTPN2 gene transfer significantly suppressed renal activation of signal transducers and activators of transcription (STAT), STAT‐dependent pro‐inflammatory and pro‐fibrotic genes expression, and influx of lymphocytes in DN, indicating anti‐inflammatory effects of PTPN2 by inhibiting the activation of STAT signalling pathway in vivo. Furthermore, PTPN2 overexpression inhibited the high‐glucose induced phosphorylation of STAT, target genes expression and proliferation in mouse mesangial and tubuloepithelial cells, suggesting that the roles of PTPN2 on STAT activation was independent of glycaemic changes. Our results demonstrated that PTPN2 gene therapy could exert protective effects on DN via ameliorating metabolic disorders and inhibiting renal STAT‐dependent micro‐inflammation, suggesting its potential role for treatment of human DN.

Macrophages: versatile players in renal inflammation and fibrosis

Macrophages have important roles in immune surveillance and in the maintenance of kidney homeostasis; their response to renal injury varies enormously depending on the nature and duration of the insult. Macrophages can adopt a variety of phenotypes: at one extreme, M1 pro-inflammatory cells contribute to infection clearance but can also promote renal injury; at the other extreme, M2 anti-inflammatory cells have a reparative phenotype and can contribute to the resolution phase of the response to injury. In addition, bone marrow monocytes can differentiate into myeloid-derived suppressor cells that can regulate T cell immunity in the kidney. However, macrophages can also promote renal fibrosis, a major driver of progression to end-stage renal disease, and the CD206⁺ subset of M2 macrophages is strongly associated with renal fibrosis in both human and experimental diseases. Myofibroblasts are important contributors to renal fibrosis and recent studies provide evidence that macrophages recruited from the bone marrow can transition directly into myofibroblasts within the injured kidney. This process is termed macrophage-to-myofibroblast transition (MMT) and is driven by transforming growth factor-β1 (TGFβ1)-Smad3 signalling via a Src-centric regulatory network. MMT may serve as a key checkpoint for the progression of chronic inflammation into pathogenic fibrosis.

Fisetin supplementation prevents high fat diet-induced diabetic nephropathy by repressing insulin resistance and RIP3-regulated inflammation

Obesity-related renal disease is related to caloric excess promoting deleterious cellular responses.

Pharmacokinetics, pharmacodynamics and safety of aptamers

Aptamers are synthetic molecules structured as single-stranded DNA or RNA oligonucleotides that can be designed to mimic the functional properties of monoclonal antibodies. They bind to the target molecules (typically soluble or cell-bound proteins) with high affinity (with picomolar to low nanomolar range) and specificity, and therefore can be an alternative to therapeutic antibodies or peptide ligands. This paper reviews published data regarding pharmacokinetics, pharmacodynamics and safety of aptamers from preclinical and clinical studies. Aptamers have been developed for the treatment of a variety of diseases, including cancer, macular degeneration,g cardiovascular disease, diabetes and anaemia of chronic diseases. There are several preclinical studies with unmodified aptamers, but the vast majority of aptamer trials in humans have been conducted with modified aptamers, because unmodified aptamers demonstrate metabolic instability, as well as rapid renal filtration and elimination. Various strategies have been developed to improve the pharmacokinetic profile of aptamers. Aside from chemical modification of nucleotides in order to stabilize them against nuclease degradation, the main modification to extend the half-life is pegylation. Therefore, the process of pegylation as well as its benefits and possible shortcomings will briefly be discussed.

MCP-1 Feedback Loop Between Adipocytes and Mesenchymal Stromal Cells Causes Fat Accumulation and Contributes to Hematopoietic Stem Cell Rarefaction in the Bone Marrow of Patients With Diabetes

Fat accumulates in bone marrow (BM) of patients with diabetes. In this study, we investigated the mechanisms and consequences of this phenomenon. BM mesenchymal stromal cells (BM-MSCs) from patients with type 2 diabetes (T2D) constitutively express adipogenic markers and robustly differentiate into adipocytes (ADs) upon in vitro induction as compared with BM-MSCs from subjects without diabetes. Moreover, BM-ADs from subjects with T2D (T2D BM-ADs) paracrinally stimulate a transcriptional adipogenic program in BM-MSCs. Antagonism of MCP-1, a chemokine pivotally expressed in T2D BM-ADs, prevented the T2D BM-AD secretome from converting BM-MSCs into ADs. Mechanistic validation of human data was next performed in an obese T2D mouse model. Systemic antagonism of MCP-1 improved metabolic control, reduced BM fat, and increased osteocyte density. It also indirectly re-established the abundance of long-term versus short-term hematopoietic stem cells. We reveal a diabetic feedback loop in which 1) BM-MSCs are constitutively inclined to make ADs, and 2) mature BM-ADs, via secreted MCP-1, relentlessly fuel BM-MSC determination into new fat. Pharmacological inhibition of MCP-1 signaling can contrast this vicious cycle, restoring, at least in part, the balance between adipogenesis and hematopoiesis in BM from subjects with T2D.

C-C motif-ligand 2 inhibition with emapticap pegol (NOX-E36) in type 2 diabetic patients with albuminuria

Background

Emapticap pegol (NOX-E36) is a Spiegelmer® that specifically binds and inhibits the pro-inflammatory chemokine C-C motif-ligand 2 (CCL2) (also called monocyte-chemotactic protein 1). The objective of this exploratory study was to evaluate the safety and tolerability as well as the renoprotective and anti-diabetic potential of emapticap in type 2 diabetic patients with albuminuria.

Methods

A randomized, double-blind, placebo-controlled Phase IIa study was initiated in 75 albuminuric type 2 diabetics. Emapticap at 0.5 mg/kg and placebo were administered subcutaneously twice weekly for 12 weeks to 50 and 25 patients, respectively, followed by a treatment-free phase of 12 weeks.

Results

Twice weekly subcutaneous treatment with emapticap over 3 months was generally safe and well tolerated and reduced the urinary albumin/creatinine ratio (ACR) from baseline to Week 12 by 29% (P < 0.05); versus placebo a non-significant ACR reduction of 15% was observed (P = 0.221). The maximum difference, 26% (P = 0.064) between emapticap and placebo, was seen 8 weeks after discontinuation of treatment. At Week 12, the HbA1c changed by −0.31% in the emapticap versus +0.05% in the placebo group (P = 0.146). The maximum difference for HbA1c was observed 4 weeks after the last dose with −0.35% for emapticap versus +0.12% for placebo (P = 0.026). No relevant change in blood pressure or estimated glomerular filtration rate was seen between the treatment groups throughout the study. A post hoc analysis with exclusion of patients with major protocol violations, dual RAS blockade or haematuria increased the ACR difference between the two treatment arms to 32% at Week 12 (P = 0.014) and 39% at Week 20 (P = 0.010).

Conclusions

Inhibition of the CCL2/CCL2 receptor axis with emapticap pegol was generally safe and well tolerated. Beneficial effects on ACR and HbA1c were observed in this exploratory study, which were maintained after cessation of treatment. Taken together, emapticap may have disease-modifying effects that warrant further investigation in adequately powered confirmatory studies.

Fibroblast growth factor 1 ameliorates diabetic nephropathy by an anti-inflammatory mechanism

Inflammation plays a central role in the etiology of diabetic nephropathy, a global health issue. We observed a significant reduction in the renal expression of fibroblast growth factor 1, a known mitogen and insulin sensitizer, in patients with diabetic nephropathy and in mouse models implying that fibroblast growth factor 1 possesses beneficial anti-inflammatory and renoprotective activities in vivo. To test this possibility, we investigated the effects of chronic intraperitoneal administration of fibroblast growth factor 1 into both the streptozotocin-induced type 1 diabetes and db/db type 2 diabetes models. Indeed, recombinant fibroblast growth factor 1 significantly suppressed renal inflammation (i.e., cytokines, macrophage infiltration), glomerular and tubular damage, and renal dysfunction in both type 1 and type 2 diabetes mice. Fibroblast growth factor 1 was able to correct the elevated blood glucose levels in type 2 but not in type 1 diabetic mice, suggesting that the anti-inflammatory effect of fibroblast growth factor 1 was independent of its glucose-lowering activity. The mechanistic study demonstrated that fibroblast growth factor 1-mediated inhibition of the renal inflammation in vivo was accompanied by attenuation of the nuclear factor κB and c-Jun N-terminal kinase signaling pathways, further validated in vitro using cultured glomerular mesangial cells and podocytes. Thus, fibroblast growth factor 1 holds great promise for developing new treatments for diabetic nephropathy through countering inflammatory signaling cascades in injured renal tissue.

Inflammation and renal fibrosis: Recent developments on key signaling molecules as potential therapeutic targets

Chronic kidney disease (CKD) is a major public health issue. At the histological level, renal fibrosis is the final common pathway of progressive kidney disease irrespective of the initial injury. Considerable evidence now indicates that renal inflammation plays a central role in the initiation and progression of CKD. Some of the inflammatory signaling molecules involved in CKD include: monocyte chemoattractant protein-1 (MCP-1), bradykinin B₁ receptor (B₁R), nuclear factor κB (NF-κB), tumor necrosis factor-α (TNFα), transforming growth factor β (TGF-β), and platelet-derived growth factor (PDGF). Multiple antifibrotic factors, such as interleukin-10 (IL-10), interferon-γ (IFN-γ), bone morphogenetic protein-7 (BMP-7), hepatocyte growth factor (HGF) are also downregulated in CKD. Therefore, restoration of the proper balance between pro- and antifibrotic signaling pathways could serve as a guiding principle for the design of new antifibrotic strategies that simultaneously target many pathways. The purpose of this review is to summarize the existing body of knowledge regarding activation of cytokine pathways and infiltration of inflammatory cells as a starting point for developing novel antifibrotic therapies to prevent progression of CKD.

Therapeutic pro-fibrogenic signaling pathways in fibroblasts

Myofibroblasts (MFs) play a critical role in the progression of chronic inflammatory and fibroproliferative diseases in different tissues/organs, whatever the etiology. Fibrosis is preceded and sustained by persistent injury and inflammatory response in a profibrogenic scenario involving mutual interactions, operated by several mediators and pathways, of MFs and related precursor cells with innate immunity cells and virtually any cell type in a defined tissue. These interactions, mediators and related signaling pathways are critical in initiating and perpetuating the differentiation of precursor cells into MFs that in different tissues share peculiar traits and phenotypic responses, including the ability to proliferate, produce ECM components, migrate and contribute to the modulation of inflammatory response and tissue angiogenesis. Literature studies related to liver, lung and kidney fibrosis have outlined a number of MF-related core regulatory fibrogenic signaling pathways conserved across these different organs and potentially targetable in order to develop effective antifibrotic therapeutic strategies.

Dual CCR2/CCR5 antagonist treatment attenuates adipose inflammation, but not microvascular complications in ob/ob mice

Diabetic peripheral neuropathy (DPN) and diabetic kidney disease (DKD) are common diabetic complications with limited treatment options. Experimental studies show that targeting inflammation using chemokine receptor (CCR) antagonists ameliorates DKD, presumably by reducing macrophage accumulation or activation. As inflammation is implicated in DPN development, we assessed whether CCR2 and CCR5 antagonism could also benefit DPN. Five-week-old ob/ob mice were fed a diet containing MK-0812, a dual CCR2-CCR5 receptor antagonist, for 8 weeks; DPN, DKD and metabolic phenotyping were then performed to determine the effect of CCR inhibition. Although MK-0812 reduced macrophage accumulation in adipose tissue, the treatment had largely no effect on metabolic parameters, nerve function or kidney disease in ob/ob mice. These results conflict with published data that demonstrate a benefit of CCR antagonists for DKD and hyperglycaemia. We conclude that CCR signaling blockade is ineffective in ob/ob mice and suspect that this is explained by the severe hyperglycaemia found in this model. It remains to be determined whether MK-0812 treatment, alone or in combination with improved glycaemic control, is useful in preventing diabetic complications in alternate animal models.

Potent long-acting rhFGF21 analog for treatment of diabetic nephropathy in db/db and DIO mice

Background

Fibroblast growth factor 21 (FGF21) is an endocrine-acting hormone that has the potential to treat diabetic nephropathy. However, development of FGF21 into a therapeutic has been hindered due to its low intrinsic bio-stability. In our previous study, we have developed a recombinant human FGF21 (rhFGF21) variant by site-directed mutagenesis and solid-phase PEGylation, which retained its biological function. The aim of this study is to elucidate whether the therapeutic effect of PEGylated rhFGF21 (PEG-rhFGF21) on diabetic nephropathy in DIO (diet induced obesity) mice is more significant than rhFGF21 in vivo.

Results

After administration with rhFGF21 and PEG-rhFGF21 for 2 months, biochemical data and histological examination showed that PEG-rhFGF21 significantly lowered lipid levels in the kidney, decreased urine albumin/creatinine ratio (ACR) and improved mesangial expansion, demonstrating that PEG-rhFGF21 was more efficacious in ameliorating functional and morphological abnormalities induced by diabetic nephropathy in db/db and DIO mice.

Conclusions

Our findings suggest that PEG-rhFGF21 treatment is more effective in treating diabetic nephropathy than rhFGF21, through enhancements of systemic metabolic alterations and anti-inflammatory mechanisms. These findings help provide a theoretical basis to develop more long-acting and efficacious protein drugs for diabetic nephropathy.

Podocyte-specific chemokine (C-C motif) receptor 2 overexpression mediates diabetic renal injury in mice

Inflammation is a central pathophysiologic mechanism that contributes to diabetes mellitus and diabetic nephropathy. Recently, we showed that macrophages directly contribute to diabetic renal injury and that pharmacological blockade or genetic deficiency of chemokine (C-C motif) receptor 2 (CCR2) confers kidney protection in diabetic nephropathy. However, the direct role of CCR2 in kidney-derived cells such as podocytes in diabetic nephropathy remains unclear. To study this, we developed a transgenic mouse model expressing CCR2 specifically in podocytes (Tg[NPHS2-Ccr2]) on a nephropathy-prone (DBA/2J) and CCR2-deficient (Ccr2^-/-) background with heterozygous Ccr2^+/- littermate controls. Diabetes was induced by streptozotocin. As expected, absence of CCR2 conferred kidney protection after nine weeks of diabetes. In contrast, transgenic CCR2 overexpression in the podocytes of Ccr2^-/- mice resulted in significantly increased albuminuria, blood urea nitrogen, histopathologic changes, kidney fibronectin and type 1 collagen expression, podocyte loss, and glomerular apoptosis after nine weeks of streptozotocin-induced diabetes. Interestingly, there was no concurrent increase in kidney macrophage recruitment or inflammatory cytokine levels in the mice. These findings support a direct role for CCR2 expression in podocytes to mediate diabetic renal injury, independent of monocyte/macrophage recruitment. Thus, targeting the CCR2 signaling cascade in podocytes could be a novel therapeutic approach for treatment of diabetic nephropathy.

Downregulation of kidney protective factors by inflammation: role of transcription factors and epigenetic mechanisms

Chronic kidney disease (CKD) is associated to an increased risk of death, CKD progression, and acute kidney injury (AKI) even from early stages, when glomerular filtration rate (GFR) is preserved. The link between early CKD and these risks is unclear, since there is no accumulation of uremic toxins. However, pathological albuminuria and kidney inflammation are frequent features of early CKD, and the production of kidney protective factors may be decreased. Indeed, Klotho expression is already decreased in CKD category G1 (normal GFR). Klotho has anti-aging and nephroprotective properties, and decreased Klotho levels may contribute to increase the risk of death, CKD progression, and AKI. In this review, we discuss the downregulation by mediators of inflammation of molecules with systemic and/or renal local protective functions, exemplified by Klotho and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a transcription factor that promotes mitochondrial biogenesis. Cytokines such as TWEAK, TNF-α, or transforming growth factor -β1 produced locally during kidney injury or released from inflammatory sites at other organs may decrease kidney expression of Klotho and PGC-1α or lead to suboptimal recruitment of these nephroprotective proteins. Transcription factors (e.g., Smad3 and NF-κB) and epigenetic mechanisms (e.g., histone acetylation or methylation) contribute to downregulate the expression of Klotho and/or PGC-1α, while histone crotonylation promotes PGC-1α expression. NF-κBiz facilitates the repressive effect of NF-κB on Klotho expression. A detailed understanding of these mediators may contribute to the development of novel therapeutic approaches to prevent CKD progression and its negative impact on mortality and AKI.

Monocyte chemoattractant protein-1 and the kidney

PURPOSE OF REVIEW

Recently, initial studies have been carried out in patients using monocyte chemoattractant protein-1 (MCP-1) inhibitors. This review summarizes the known function of MCP-1 in regulating monocytes during inflammation and its role in inflammatory disease of the kidney.

RECENT FINDINGS

MCP-1 is one of the first chemokines described and plays an important role in renal inflammatory disease. The function of MCP-1 has been investigated and analyzed in both animal models of renal disease and renal patients. MCP-1 mediates firstly the release of monocytes from the bone marrow, and then generates a gradient in the endothelial glycocalyx to direct monocytes to sites of inflammation, thereby alleviating the migration of blood leukocytes into the inflamed tissue. In addition, MCP-1 has direct signaling effects in monocytes and influences migration, proliferation, and differentiation of leukocytes. Blockade of MCP-1 in several models of renal disease has ameliorated the disease, suggesting that inhibition of MCP-1 is a promising and valid strategy to treat patients with renal inflammatory disease.

SUMMARY

Understanding the role of MCP-1 in monocyte homeostasis and the implications of MCP-1 inhibition in renal disease will help in designing better diagnostic and therapeutic strategies in patients with inflammatory renal disease.