The MCP-1/CCR2 axis in podocytes is involved in apoptosis induced by diabetic conditions

Podocyte-Specific Deletion of MCP-1 Fails to Protect against Angiotensin II- or Adriamycin-Induced Glomerular Disease

Investigating the role of podocytes in proteinuric disease is imperative to address the increasing global burden of chronic kidney disease (CKD). Studies strongly implicate increased levels of monocyte chemoattractant protein-1 (MCP-1/CCL2) in proteinuric CKD. Since podocytes express the receptor for MCP-1 (i.e., CCR2), we hypothesized that podocyte-specific MCP-1 production in response to stimuli could activate its receptor in an autocrine manner, leading to further podocyte injury. To test this hypothesis, we generated podocyte-specific MCP-1 knockout mice (Podo-Mcp-1fl/fl) and exposed them to proteinuric injury induced by either angiotensin II (Ang II; 1.5 mg/kg/d, osmotic minipump) or Adriamycin (Adr; 18 mg/kg, intravenous bolus). At baseline, there were no between-group differences in body weight, histology, albuminuria, and podocyte markers. After 28 days, there were no between-group differences in survival, change in body weight, albuminuria, kidney function, glomerular injury, and tubulointerstitial fibrosis. The lack of protection in the knockout mice suggests that podocyte-specific MCP-1 production is not a major contributor to either Ang II- or Adr-induced glomerular disease, implicating that another cell type is the source of pathogenic MCP-1 production in CKD.

The extract of Polygala fallax Hemsl. slows the progression of diabetic nephropathy by targeting TLR4 anti-inflammation and MMP-2/9-mediated anti-fibrosis in vitro

BACKGROUND

Polygala fallax Hemsl. is a plant that is commonly used as a folk medicine by Guangxi ethnic minorities, and it is also widely used in the clinical treatment of chronic diseases in China. The extract of P. fallax (EPF) contains key biologically active components from the roots and stems. However, the role of P. fallax or EPF in diabetic nephropathy (DN) is unclear.

PURPOSE

This study aimed to investigate the effects and mechanisms of EPF on high glucose (HG)-induced human glomerular mesangial cell (HMC) injury, inflammation, fibrosis, and apoptosis in vitro.

METHODS

For the in vitro study, MTT and ELISA assays were performed with HG-treated HMCs, as well as MMP, Hoechst, flow cytometry, qRT-PCR, and western blot analyses. The expression of the TLR4/NF-κB pathway, along with its downstream inflammatory, apoptosis, and fibrosis factors, was measured. The expression of the TLR4/NF-κB pathway and its downstream inflammatory factors were also measured after the addition of TLR4 inhibitors.

RESULTS

Our results suggest that EPF can reverse the hyperproliferation and apoptosis of HMCs induced by HG. In addition, the extract inhibited the increase in inflammatory factors IL-6, TNF-α, IL-1β, MCP-1, and IL-18 in cells treated with HG. The mRNA and protein expression of TLR4, MyD88, NF-κB, Col IV, FN, MMP-9, and MMP-2 were downregulated by EPF. In addition, EPF significantly reduced the loss of MMP and the upregulation of Bcl-2/Bax mRNA and protein levels after HG treatment.

CONCLUSION

These results demonstrated that EPF protects against diabetes-induced renal injury in vitro. EPF protected against HG-induced HMCs proliferation, apoptosis, fibrosis, and inflammation likely via inhibition of TLR4-dependent NF-κB signaling. This herbal extract may also be a novel treatment for DN.

Mechanisms of podocyte injury and implications for diabetic nephropathy

Albuminuria is the hallmark of both primary and secondary proteinuric glomerulopathies, including focal segmental glomerulosclerosis (FSGS), obesity-related nephropathy, and diabetic nephropathy (DN). Moreover, albuminuria is an important feature of all chronic kidney diseases (CKDs). Podocytes play a key role in maintaining the permselectivity of the glomerular filtration barrier (GFB) and injury of the podocyte, leading to foot process (FP) effacement and podocyte loss, the unifying underlying mechanism of proteinuric glomerulopathies. The metabolic insult of hyperglycemia is of paramount importance in the pathogenesis of DN, while insults leading to podocyte damage are poorly defined in other proteinuric glomerulopathies. However, shared mechanisms of podocyte damage have been identified. Herein, we will review the role of haemodynamic and oxidative stress, inflammation, lipotoxicity, endocannabinoid (EC) hypertone, and both mitochondrial and autophagic dysfunction in the pathogenesis of the podocyte damage, focussing particularly on their role in the pathogenesis of DN. Gaining a better insight into the mechanisms of podocyte injury may provide novel targets for treatment. Moreover, novel strategies for boosting podocyte repair may open the way to podocyte regenerative medicine.

Elevated CCL2 causes Leydig cell malfunction in metabolic syndrome

Metabolic syndrome (MetS), which is associated with chronic inflammation, predisposes males to hypogonadism and subfertility. The underlying mechanism of these pathologies remains poorly understood. Homozygous leptin-resistant obese db/db mice are characterized by small testes, low testicular testosterone, and a reduced number of Leydig cells. Here we report that IL-1β, CCL2 (also known as MCP-1), and corticosterone concentrations were increased in the testes of db/db mice relative to those in WT controls. Cultured murine and human Leydig cells responded to cytokine stress with increased CCL2 release and apoptotic signals. Chemical inhibition of CCL2 rescued Leydig cell function in vitro and in db/db mice. Consistently, we found that Ccl2-deficient mice fed with a high-energy diet were protected from testicular dysfunction compared with similarly fed WT mice. Finally, a cohort of infertile men with a history of MetS showed that reduction of CCL2 plasma levels could be achieved by weight loss and was clearly associated with recovery from hypogonadism. Taken together, we conclude that CCL2-mediated chronic inflammation is, to a large extent, responsible for the subfertility in MetS by causing damage to Leydig cells.

MCP-1/CCL2 upregulation associates with metabolic syndrome–induced male subfertility in both mice and men.

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.

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.

The atypical chemokine receptor 2 limits renal inflammation and fibrosis in murine progressive immune complex glomerulonephritis

The atypical chemokine receptor 2 (ACKR2), also named D6, regulates local levels of inflammatory chemokines by internalization and degradation. To explore potential anti-inflammatory functions of ACKR2 in glomerulonephritis, we induced autologous nephrotoxic nephritis in C57/BL6 wild-type and Ackr2-deficient mice. Renal ACKR2 expression increased and localized to interstitial lymphatic endothelium during nephritis. At two weeks Ackr2^-/-mice developed increased albuminuria and urea levels compared to wild-type mice. Histological analysis revealed increased structural damage in the glomerular and tubulointerstitial compartments within Ackr2^-/- kidneys. This correlated with excessive renal leukocyte infiltration of CD4⁺ T cells and mononuclear phagocytes with increased numbers in the tubulointerstitium but not glomeruli in knockout mice. Expression of inflammatory mediators and especially markers of fibrotic tissue remodeling were increased along with higher levels of ACKR2 inflammatory chemokine ligands like CCL2 in nephritic Ackr2^-/- kidneys. In vitro, Ackr2 deficiency in TNF-stimulated tubulointerstitial tissue but not glomeruli increased chemokine levels. These results are in line with ACKR2 expression in interstitial lymphatic endothelial cells, which also assures efflux of activated leukocytes into regional lymph nodes. Consistently, nephritic Ackr2^-/- mice showed reduced adaptive cellular immune responses indicated by decreased regional T-cell activation. However, this did not prevent aggravated injury in the kidneys of Ackr2^-/- mice with nephrotoxic nephritis due to simultaneously increased tubulointerstitial chemokine levels, leukocyte infiltration and fibrosis. Thus, ACKR2 is important in limiting renal inflammation and fibrotic remodeling in progressive nephrotoxic nephritis. Hence, ACKR2 may be a potential target for therapeutic interventions in immune complex glomerulonephritis.

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.

Emerging therapeutics for the treatment of diabetic nephropathy

Diabetic nephropathy (DN) is the most common pathology contributing to the development of chronic kidney disease (CKD). DN caused by hypertension and unmitigated inflammation in diabetics, renders the kidneys unable to perform normally, and leads to renal fibrosis and organ failure. The increasing global prevalence of DN has been directly attributed to rising incidences of Type II diabetes, and is now the largest non-communicable cause of death worldwide. Despite the high morbidity, successful new treatments for DN are lacking. This review seeks to provide new insight on emerging clinical candidates under investigation for the treatment of DN.

Gene silencing of MCP-1 prevents microglial activation and inflammatory injury after intracerebral hemorrhage

Microglia are activated after intracerebral hemorrhage and induce neuron death by releasing proinflammatory cytokines and chemokines. However, the related mechanism of microglia activation in such conditions remains elusive. MCP-1, the ligand of CCR2 expressed in the central nervous system, could promote microglia proliferation, survival and cytokine secretion. According to the previous findings, we make a hypothesis that whether alternation of MCP-1 level could attenuate microglia activation and toxicity to neuron in intracerebral hemorrhage. To identify that, we interfere with the MCP-1 expression of microglia by RNAi technology, and coculture the microglia and neuron in ICH. The results demonstrated that MCP-1 RNAi inhibited TNF-α, IL-1β and IL-6 expression in microglia and attenuated neuron injury. In conclusion, the present study suggests that MCP-1 might promote ICH induced microglia activation and toxicity to neuron, and MCP-1 RNAi might provide promising therapeutical strategy for ICH.

Renal Protection by Genetic Deletion of the Atypical Chemokine Receptor ACKR2 in Diabetic OVE Mice

In diabetic nephropathy (DN) proinflammatory chemokines and leukocyte infiltration correlate with tubulointerstitial injury and declining renal function. The atypical chemokine receptor ACKR2 is a chemokine scavenger receptor which binds and sequesters many inflammatory CC chemokines but does not transduce typical G-protein mediated signaling events. ACKR2 is known to regulate diverse inflammatory diseases but its role in DN has not been tested. In this study, we utilized ACKR2(-/-) mice to test whether ACKR2 elimination alters progression of diabetic kidney disease. Elimination of ACKR2 greatly reduced DN in OVE26 mice, an established DN model. Albuminuria was significantly lower at 2, 4, and 6 months of age. ACKR2 deletion did not affect diabetic blood glucose levels but significantly decreased parameters of renal inflammation including leukocyte infiltration and fibrosis. Activation of pathways that increase inflammatory gene expression was attenuated. Human biopsies stained with ACKR2 antibody revealed increased staining in diabetic kidney, especially in some tubule and interstitial cells. The results demonstrate a significant interaction between diabetes and ACKR2 protein in the kidney. Unexpectedly, ACKR2 deletion reduced renal inflammation in diabetes and the ultimate response was a high degree of protection from diabetic nephropathy.

G protein-coupled receptors: potential therapeutic targets for diabetic nephropathy

Diabetic nephropathy, a lethal microvascular complication of diabetes mellitus, is characterized by progressive albuminuria, excessive deposition of extracellular matrix, thickened glomerular basement membrane, podocyte abnormalities, and podocyte loss. The G protein-coupled receptors (GPCRs) have attracted considerable attention in diabetic nephropathy, but the specific effects have not been elucidated yet. Likewise, abnormal signaling pathways are closely interrelated to the pathologic process of diabetic nephropathy, despite the fact that the mechanisms have not been explored clearly. Therefore, GPCRs and its mediated signaling pathways are essential for priority research, so that preventative strategies and potential targets might be developed for diabetic nephropathy. This article will give us comprehensive overview of predominant GPCR types, roles, and correlative signaling pathways in diabetic nephropathy.

Renal Lipotoxicity-Associated Inflammation and Insulin Resistance Affects Actin Cytoskeleton Organization in Podocytes

In the last few decades a change in lifestyle has led to an alarming increase in the prevalence of obesity and obesity-associated complications. Obese patients are at increased risk of developing hypertension, heart disease, insulin resistance (IR), dyslipidemia, type 2 diabetes and renal disease. The excess calories are stored as triglycerides in adipose tissue, but also may accumulate ectopically in other organs, including the kidney, which contributes to the damage through a toxic process named lipotoxicity. Recently, the evidence suggests that renal lipid accumulation leads to glomerular damage and, more specifically, produces dysfunction in podocytes, key cells that compose and maintain the glomerular filtration barrier. Our aim was to analyze the early mechanisms underlying the development of renal disease associated with the process of lipotoxicity in podocytes. Our results show that treatment of podocytes with palmitic acid produced intracellular accumulation of lipid droplets and abnormal glucose and lipid metabolism. This was accompanied by the development of inflammation, oxidative stress and endoplasmic reticulum stress and insulin resistance. We found specific rearrangements of the actin cytoskeleton and slit diaphragm proteins (Nephrin, P-Cadherin, Vimentin) associated with this insulin resistance in palmitic-treated podocytes. We conclude that lipotoxicity accelerates glomerular disease through lipid accumulation and inflammation. Moreover, saturated fatty acids specifically promote insulin resistance by disturbing the cytoarchitecture of podocytes. These data suggest that renal lipid metabolism and cytoskeleton rearrangements may serve as a target for specific therapies aimed at slowing the progression of podocyte failure during metabolic syndrome.

Inflammation in diabetic nephropathy: moving toward clinical biomarkers and targets for treatment

Diabetic nephropathy (DN) is a leading cause of end stage renal failure and there is an urgent need to identify new clinical biomarkers and targets for treatment to effectively prevent and slow the progression of the complication. Many lines of evidence show that inflammation is a cardinal pathogenetic mechanism in DN. Studies in animal models of experimental diabetes have demonstrated that there is a low-grade inflammation in the diabetic kidney. Both pharmacological and genetic strategies targeting inflammatory molecules have been shown to be beneficial in experimental DN. In vitro studies have cast light on the cellular mechanisms whereby diabetes triggers inflammation and in turn inflammation magnifies the kidney injury. Translation of this basic science knowledge into potential practical clinical applications is matter of great interest for researchers today. This review focuses on key pro-inflammatory systems implicated in the development of DN: the tumor necrosis factor(TNF)-α/TNF-α receptor system, the monocyte chemoattractant protein-1/CC-chemokine receptor-2 system, and the Endocannabinoid system that have been selected as they appear particularly promising for future clinical applications.

Functional interaction between angiotensin II receptor type 1 and chemokine (C-C motif) receptor 2 with implications for chronic kidney disease

Understanding functional interactions between G protein-coupled receptors is of great physiological and pathophysiological importance. Heteromerization provides one important potential mechanism for such interaction between different signalling pathways via macromolecular complex formation. Previous studies suggested a functional interplay between angiotensin II receptor type 1 (AT1) and Chemokine (C-C motif) Receptor 2 (CCR2). However the molecular mechanisms are not understood. We investigated AT1-CCR2 functional interaction in vitro using bioluminescence resonance energy transfer in HEK293 cells and in vivo using subtotal-nephrectomized rats as a well-established model for chronic kidney disease. Our data revealed functional heteromers of these receptors resulting in CCR2-Gαi1 coupling being sensitive to AT1 activation, as well as apparent enhanced β-arrestin2 recruitment with agonist co-stimulation that is synergistically reversed by combined antagonist treatment. Moreover, we present in vivo findings where combined treatment with AT1- and CCR2-selective inhibitors was synergistically beneficial in terms of decreasing proteinuria, reducing podocyte loss and preventing renal injury independent of blood pressure in the subtotal-nephrectomized rat model. Our findings further support a role for G protein-coupled receptor functional heteromerization in pathophysiology and provide insights into previous observations indicating the importance of AT1-CCR2 functional interaction in inflammation, renal and hypertensive disorders.

Fighting against kidney diseases with small interfering RNA: opportunities and challenges

The significant improvements in siRNA therapy have been achieved, which have great potential applications in humans. The kidney is a comparatively easy target organ of siRNA therapy due to its unique structural and functional characteristics. Here, we reviewed recent achievements in siRNA design, delivery and application with focuses on kidney diseases, in particular kidney transplant-related injuries. In addition, the strategy for increasing serum stability and immune tolerance of siRNA was also discussed. At last, the future challenges of siRNA therapy including organ/tissue/cell-specific delivery and time-controlled silence, as well as selecting therapeutic targets, were addressed as well.

Monocyte chemoattractant protein 1 (MCP-1/CCL2) contributes to thymus atrophy in acute myeloid leukemia

Recent studies on acute myelogenous leukemia (AML) patients have revealed the existence of T-cell immunodeficiencies, characterized by peripheral T lymphocytes that are unable to interact with blasts, reduced thymic emigrants and oligoclonal restricted repertoires. These observations suggest that there is a profound thymic dysregulation, which is difficult to study in AML patients. Using the C1498 AML mouse model, we demonstrated that leukemia development was associated with thymus atrophy, which was defined by abnormal organ weight and reduced cellularity. In addition, we observed a dramatic loss of peripheral CD4(+) and CD8(+) T-cell numbers with increased frequencies of CD4(+) FoxP3(+) regulatory and activated/memory T cells. Investigating the mechanisms leading to this atrophy, we observed a significant accumulation of the monocyte chemoattractant protein 1 (MCP-1/CCL2) in thymi of leukemic mice. Treatment of AML-bearing animals with a blocking anti-CCL2 antibody revealed a lower tumor burden, augmented antileukemic T-cell responses, and improved survival rate compared to nontreated mice. These results were not observed when neutralization of CCL2 was performed in thymectomized mice. Altogether, we show that the CCL2 protein participates in thymic atrophy in AML mice, and this could have important implications for future immunotherapeutic strategies.

The effect of statin on epithelial-mesenchymal transition in peritoneal mesothelial cells

Background

Statins have recently been highlighted for their pleiotropic actions distinct from cholesterol-lowering effects. Despite this interest, it is currently unknown whether statin therapy inhibits peritoneal dialysis (PD)-related epithelial-mesenchymal transition (EMT).

Methods

In vitro, human peritoneal mesothelial cells (HPMCs) were exposed to 5.6 mM glucose (NG) or 100 mM glucose (HG) with or without simvastatin (1 µM). In vivo, PD catheters were inserted into 32 Sprague-Dawley rats, and saline (C, n = 16) or 4.25% peritoneal dialysis fluid (PDF) (PD, n = 16) was infused for 4 weeks. Eight rats from each group were treated with 5 mg/kg/day of simvastatin intraperitoneally. Changes in the protein expression of EMT markers such as E-cadherin, α-SMA, Snail, and fibronectin in HPMCs and the peritoneum were evaluated by Western blot analysis and immunofluorescence or immunohistochemical staining. We also explored whether activation of the mevalonate pathway and its downstream small GTPases were involved in dialysis-related peritoneal EMT and could be inhibited by statin treatment.

Results

Compared to NG cells, E-cadherin expression was significantly decreased, while α-SMA, Snail, and fibronectin expression were significantly increased in HPMCs exposed to HG, and these changes were abrogated by simvastatin (p<0.05). In addition, the cobblestone-like appearance of normal HPMCs was converted into a fibroblast-like morphology after HG treatment, which was reversed by simvastatin. These EMT-like changes were also observed in HPMCs treated with geranyl-geranyl pyrophosphate (5 µM). HG significantly increased the protein expression of RhoA and Rac1 in the membrane fractions, and these increases were ameliorated by simvastatin (p<0.05). In PD rats, E-cadherin in the peritoneum was significantly decreased, whereas α-SMA, Snail, and fibronectin expression were significantly increased (p<0.05) compared to C rats. The thickness of the mesothelial layer in the peritoneum were also significantly greater in PD rats than in C rats (p<0.05). These changes of the peritoneum in PD rats were significantly attenuated by simvastatin.

Conclusion

This study demonstrated that PD-related EMT was mediated via the mevalonate pathway, and statin treatment inhibited the EMT changes in HG-treated HPMCs and PDF-stimulated PD rats. These findings suggest that statins may be a promising therapeutic strategy for preservation of peritoneal membrane integrity in long-term PD patients.

Alleviation of podocyte injury: the possible pathway implicated in anti-inflammation of alpha-lipoic acid in type 2 diabetics

BACKGROUND AND AIMS

The objective of this study is to observe the effect of alpha-lipoic acid (ALA) on Pod injury by anti-inflammation and explore its possible renal protective mechanism.

METHODS

A total of 36 cases with type 2 diabetes with microalbuminuria and fasting plasma glucose (FPG) levels less than 9 mmol/L and glycated hemoglobin A1c (HbA1c) ≤9.0 % were recruited to be treated with ALA (600 mg, daily) for 6 months (group DA). Another 30 healthy individuals were chosen as normal controls (group NC). The levels of serum creatinine (Cr), FPG, and HbA1c were detected; blood pressure was recorded; and early morning urine samples (corrected for urinary Cr) were collected for the examination of urinary monocyte chemoattractant protein-1 (MCP-1), transforming growth factor-β1 (TGF-β1), podocalyxin (PCX), nephrin, albumin and Cr in group NC and group DA at the baseline and the sixth month.

RESULTS

The excretions of urinary MCP-1, TGF-β1, PCX, nephrin and albumin to Cr ratio (abbreviated as UMCR, UTCR, UPCR, UNCR and UACR respectively) were significantly increased in group DA compared with group NC (all P < 0.01), and after 6-month treatment, all indexes mentioned above decreased markedly (P < 0.05), while FPG and HbA1c had no obvious changes. Additionally, there was a positive correlation between UMCR, UTCR with UPCR, UNCR and UACR, respectively (all P < 0.01).

CONCLUSIONS

Anti-inflammation of ALA in vivo and local kidney is implicated in the protection of glomerular Pod injury in patients with type 2 diabetes.

Urinary concentration of monocyte chemoattractant protein-1 in idiopathic glomerulonephritis: a long-term follow-up study

Background

Monocyte chemoattractant protein-1 (MCP-1), which is up regulated in kidney diseases, is considered a marker of kidney inflammation. We examined the value of urine MCP-1 in predicting the outcome in idiopathic glomerulonephritis.

Methods

Between 1993 and 2004, 165 patients (68 females) diagnosed with idiopathic proteinuric glomerulopathy and with serum creatinine <150 µmol/L at diagnosis were selected for the study. Urine concentrations of MCP-1 were analyzed by ELISA in early morning spot urine samples collected on the day of the diagnostic kidney biopsy. The patients were followed until 2009. The progression rate to end-stage kidney disease was calculated using Kaplan–Meier survival analysis. End-stage kidney disease (ESKD) was defined as the start of kidney replacement therapy during the study follow-up time.

Results

Patients with proliferative glomerulonephritis had significantly higher urinary MCP-1 excretion levels than those with non-proliferative glomerulonephritis (p<0.001). The percentage of patients whose kidney function deteriorated significantly was 39.0% in the high MCP-1 excretion group and 29.9% in the low MCP-1 excretion group. However, after adjustment for confounding variables such as glomerular filtration rate (GFR) and proteinuria, there was no significant association between urine MCP-1 concentration and progression to ESKD, (HR = 1.75, 95% CI = 0.64–4.75, p = 0.27).

Conclusion

Our findings indicate that progression to end-stage kidney disease in patients with idiopathic glomerulopathies is not associated with urine MCP-1 concentrations at the time of diagnosis.

Defective TGF-β signaling in bone marrow-derived cells prevents hedgehog-induced skin tumors

Hedgehog signaling in cancer cells drives changes in the tumor microenvironment that are incompletely understood. Here, we report that hedgehog-driven tumors exhibit an increase in myeloid-derived suppressor cells (MDSC) and a decrease in T cells, indicative of an immunosuppressive tumor microenvironment. This change was associated with activated TGF-β signaling in several cell types in basal cell carcinomas. We determined that TGF-β signaling in bone marrow-derived cells, not keratinocytes, regulates MDSC and promotes tumor development. Tgfbr2 deficiency in the bone marrow-derived cells also reduced the size of previously developed tumors in mice. We identified CCL2 as the major chemokine attracting MDSCs to tumor, whose expression was Tgfbr2-dependent, whereas its receptor CCR2 was highly expressed in MDSC population. CCL2 alone was sufficient to induce migration of MDSCs. Moreover, the CCR2 inhibitors prevented MDSC migration toward skin cells in vitro, and reduced MDSC accumulation and hedgehog signaling-driven tumor development in mice. Our results reveal a signaling network critical for hedgehog signaling in cancer cells to establish an effective immunosuppressive microenvironment during tumor development.

Attenuation of diabetic nephropathy by Chaihuang-Yishen granule through anti-inflammatory mechanism in streptozotocin-induced rat model of diabetics

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medical herbs have been used in China for a long time to treat different diseases. Based on traditional Chinese medicine (TCM) principle, Chaihuang-Yishen granule (CHYS) was developed and has been employed clinically to treat chronic kidney disease including diabetic nephropathy (DN). The present study was designed to investigate its mechanism of action in treatment of DN.

MATERIALS AND METHODS

Diabetic rats were established by having a right uninephrectomy plus a single intraperitoneal injection of STZ. Rats were divided into four groups of sham, diabetes, diabetes with CHYS and diabetes with fosinopril. CHYS and fosinopril were given to rats by gavage for 20 weeks. Samples from blood, urine and kidney were collected for biochemical, histological, immunohistochemical and molecular analyses.

RESULTS

Rats treated with CHYS showed reduced 24h urinary protein excretion, decreased serum TC and TG levels, but CHYS treatment did not affect blood glucose level. Glomerular mesangial expansion and tubulointerstitial fibrosis in diabetic rats were significantly alleviated by CHYS treatment. Moreover, CHYS administration markedly reduced mRNA levels of NF-κB p65 and TGF-β1, as well as decreased protein levels of NF-κB p65, MCP-1, TNF-α and TGF-β1 in the kidney of diabetic rats.

CONCLUSIONS

CHYS ameliorates renal injury in diabetic rats through reduction of inflammatory cytokines and their intracellular signaling.

Fn14 in podocytes and proteinuric kidney disease

Non-proliferative proteinuric diseases are the most common primary glomerular disorders causing end-stage renal disease. These disorders may associate low level glomerular inflammation and podocyte expression of inflammatory mediators. However, the factors regulating podocyte expression of inflammatory mediators in vivo in non-immune disorders are poorly understood. We have now explored the regulation and role of TWEAK receptor Fn14 in mediating glomerular inflammation in cultured podocytes and in experimental and human non-immune proteinuria. Transcriptomics disclosed Fn14 and MCP-1 mRNA upregulation in glomeruli from patients with focal segmental glomerulosclerosis, as well as a correlation between the expression of both transcripts. Increased glomerular Fn14 and MCP-1 mRNA was confirmed in a second focal segmental glomerulosclerosis cohort and was also observed in membranous nephropathy. In human non-proliferative proteinuric kidney diseases podocytes displayed Fn14 and MCP-1 expression and NFκB activation. Podocyte Fn14 was increased in murine protein overload-induced proteinuria. In Fn14 knock-out mice with protein overload-induced proteinuria, glomerular and periglomerular macrophage infiltrates were reduced, as were MCP-1 mRNA and podocyte MCP-1 staining and podocyte numbers preserved as compared to wild-type counterparts. Adenovirus-mediated overexpression of TWEAK increased periglomerular macrophage infiltration in mice without prior kidney injury. In cultured podocytes inflammatory cytokines increased Fn14 mRNA and protein levels. TWEAK activated NFκB and increased MCP-1 mRNA and protein, an effect prevented by the NFκB inhibitor parthenolide. In conclusion, Fn14 activation results in NFκB-mediated pro-inflammatory effects on podocytes that may be relevant for the pathogenesis of non-proliferative proteinuric kidney disease of non-immune origin.

Inflammation and the pathogenesis of diabetic nephropathy

The most problematic issue in clinical nephrology is the relentless and progressive increase in patients with ESRD (end-stage renal disease) worldwide. The impact of diabetic nephropathy on the increasing population with CKD (chronic kidney disease) and ESRD is enormous. Three major pathways showing abnormality of intracellular metabolism have been identified in the development of diabetic nephropathy: (i) the activation of polyol and PKC (protein kinase C) pathways; (ii) the formation of advanced glycation end-products; and (iii) intraglomerular hypertension induced by glomerular hyperfiltration. Upstream of these three major pathways, hyperglycaemia is the major driving force of the progression to ESRD from diabetic nephropathy. Downstream of the three pathways, microinflammation and subsequent extracellular matrix expansion are common pathways for the progression of diabetic nephropathy. In recent years, many researchers have been convinced that the inflammation pathways play central roles in the progression of diabetic nephropathy, and the identification of new inflammatory molecules may link to the development of new therapeutic strategies. Various molecules related to the inflammation pathways in diabetic nephropathy include transcription factors, pro-inflammatory cytokines, chemokines, adhesion molecules, Toll-like receptors, adipokines and nuclear receptors, which are candidates for the new molecular targets for the treatment of diabetic nephropathy. Understanding of these molecular pathways of inflammation would translate into the development of anti-inflammation therapeutic strategies.

The monocyte chemoattractant protein-1 (MCP-1)/CCR2 system is involved in peritoneal dialysis-related epithelial-mesenchymal transition of peritoneal mesothelial cells

Epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) has a role in the process of peritoneal fibrosis (PF), a serious complication in peritoneal dialysis (PD) patients. Even though monocyte chemoattractant protein-1 (MCP-1) was demonstrated to directly increase extracellular matrix (ECM) synthesis, the role of the MCP-1/CCR2 system in PD-related EMT and ECM synthesis in cultured human PMCs (HPMCs) and in an animal model of PD has never been elucidated. In vitro, HPMCs were exposed to 5.6 mM glucose (NG), NG+MCP-1 (10 ng/ml) (NG+MCP-1), or 100 mM glucose (HG) with or without CCR2 inhibitor (RS102895) (CCR2i) or a dominant-negative mutant MCP-1-expressing lentivirus (LV-mMCP-1). In vivo, PD catheters were inserted into 60 Sprague-Dawley rats, and saline (Control, C) (N=30) or 4.25% PD solution (PD) (N=30) was infused for 4 weeks. Twenty rats from each group were treated with empty LV or LV-mMCP-1 intraperitoneally. Snail, E-cadherin, α-smooth muscle actin (α-SMA), and fibronectin protein expression in HPMCs and the peritoneum was evaluated by western blot analysis. Compared with NG cells, Snail, α-SMA, and fibronectin expression was significantly increased, while E-cadherin expression was significantly decreased in HPMCs exposed to HG and NG+MCP-1, and these changes were significantly abrogated by CCR2i (P<0.05). In addition, MCP-1-induced EMT was significantly attenuated by anti-TGF-β1 antibody. In PD rats, Snail and fibronectin expression was significantly increased in the peritoneum, whereas the ratios of E-cadherin/α-SMA protein expression were significantly decreased (P<0.05). The thickness of the peritoneum and the intensity of Masson's trichrome staining in the peritoneum were also significantly higher in PD rats than in C rats (P<0.05). These changes in PD rats were significantly abrogated by LV-mMCP-1. These findings suggest that the MCP-1/CCR2 system is directly involved in PD-related EMT and ECM synthesis and that this is mediated, at least in part, via TGF-β1.

Role of TGF-β in chronic kidney disease: an integration of tubular, glomerular and vascular effects

Transforming growth factor beta (TGF-β) has been recognized as an important mediator in the genesis of chronic kidney diseases (CKD), which are characterized by the accumulation of extracellular matrix (ECM) components in the glomeruli (glomerular fibrosis, glomerulosclerosis) and the tubular interstitium (tubulointerstitial fibrosis). Glomerulosclerosis is a major cause of glomerular filtration rate reduction in CKD and all three major glomerular cell types (podocytes or visceral epithelial cells, mesangial cells and endothelial cells) participate in the fibrotic process. TGF-β induces (1) podocytopenia caused by podocyte apoptosis and detachment from the glomerular basement membrane; (2) mesangial expansion caused by mesangial cell hypertrophy, proliferation (and eventually apoptosis) and ECM synthesis; (3) endothelial to mesenchymal transition giving rise to glomerular myofibroblasts, a major source of ECM. TGF-β has been shown to mediate several key tubular pathological events during CKD progression, namely fibroblast proliferation, epithelial to mesenchymal transition, tubular and fibroblast ECM production and epithelial cell death leading to tubular cell deletion and interstitial fibrosis. In this review, we re-examine the mechanisms involved in glomerulosclerosis and tubulointerstitial fibrosis and the way that TGF-β participates in renal fibrosis, renal parenchyma degeneration and loss of function associated with CKD.