A high glucose concentration stimulates the expression of monocyte chemotactic peptide 1 in human mesangial cells

The effect and mechanism of freeze-dried powder of Poecilobdella manillensis on improving inflammatory injury of rat glomerular mesangial cells through TXNIP / NLRP3 pathway

Objective

Diabetic kidney disease (DKD) is a common complication of diabetes mellitus. The pathophysiological changes in platelet function and the hypercoagulable state associated with DKD are closely linked to inflammatory processes. Poecilobdella manillensis (PM), a type of leech known for its anticoagulant and antithrombotic properties, has the potential to modulate the inflammatory response in DKD. This study aims to investigate the effect of freeze-dried powder of PM on improving inflammatory injury in rat glomerular mesangial cells and to explore its underlying mechanism.

Methods

Lipopolysaccharide (LPS) stimulated HBZY-1 rat mesangial cells to establish an in vitro DKD inflammation model. After the intervention with the water extract of freeze-dried powder of PM (FDPM), cell viability, NO content, and the levels of inflammatory factors such as IL-1β, IL-18, and TNF-α were assessed. Finally, utilizing transcriptomics technology, RT-qPCR, and Western blot methods, the mechanism by which FDPM improves inflammatory injury in rat glomerular mesangial cells was explored and preliminarily validated.

Results

FDPM effectively enhances cell viability and inhibits the production of NO and related inflammatory factors. Transcriptomic analysis suggests that FDPM may exert these effects by regulating the TXNIP/NLRP3 signaling pathway. The mRNA and protein expressions of TXNIP, NLRP3, and MCP-1 in the model cells were reversed by FDPM.

Conclusion

FDPM may improve the micro-inflammatory state of DKD and slow the progression of the disease by regulating the TXNIP/NLRP3 signaling pathway. This study provides a scientific basis for the clinical application of PM DKD treatment.

The importance of the enzyme Gamma-glutamyltransferase in the pathogenic cluster in type2 diabetic patient

Introduction. Gamma-glutamyltransferase (GGT) is a liver enzyme involved in inflammation and oxidative stress. It is already known that MCP-1 (Monocyte Chemoattractant Protein-1) and TNF-α (tumour necrosis factor) as inflammatory markers, ICAM-1 (Intercellular Adhesion Molecule-1) as an endothelial dysfunctional marker, and glutathione, as an antioxidant, have abnormal levels in type 2 diabetic patients. The aim of this study was to evaluate the specific biological picture of type 2 diabetic patients that also associate higher GGT activity. Methods. Eighty-five type 2 diabetes, aged 40-70 years with a duration of diabetes less than 6 years without infections, epilepsy, chronic liver or cardiac diseases, without alcohol consumption (>20 g/day) were divided in two subgroups, those with normal and those with high abnormal GGT. Results. The diabetic patients with high GGT (n=31) had dysglycaemia, dyslipidemia, higher inflammatory markers (CRP, TNF-α, MCP-1) and endothelial dysfunction (high leptin and sICAM). sICAM, serum MCP-1 and TNF-α levels had significant correlations with GGT activity (r= 0.38, r=0.30 and 0.26 respectively, p<0.05). Conclusion. This study underlines that in non-alcoholic diabetic patients, with a duration of the metabolic disease less than 6 years, sICAM, serum MCP-1 and TNF-α might play an important role in dysmetabolism, and higher level for GGT represents the "red flag" for this condition.

The Mechanism of Hyperglycemia-Induced Renal Cell Injury in Diabetic Nephropathy Disease: An Update

Diabetic Nephropathy (DN) is a serious complication of type I and II diabetes. It develops from the initial microproteinuria to end-stage renal failure. The main initiator for DN is chronic hyperglycemia. Hyperglycemia (HG) can stimulate the resident and non-resident renal cells to produce humoral mediators and cytokines that can lead to functional and phenotypic changes in renal cells and tissues, interference with cell growth, interacting proteins, advanced glycation end products (AGEs), etc., ultimately resulting in glomerular and tubular damage and the onset of kidney disease. Therefore, poor blood glucose control is a particularly important risk factor for the development of DN. In this paper, the types and mechanisms of DN cell damage are classified and summarized by reviewing the related literature concerning the effect of hyperglycemia on the development of DN. At the cellular level, we summarize the mechanisms and effects of renal damage by hyperglycemia. This is expected to provide therapeutic ideas and inspiration for further studies on the treatment of patients with DN.

How to inhibit transforming growth factor beta safely in diabetic kidney disease

PURPOSE OF REVIEW

Diabetic kidney disease (DKD) is a leading cause of mortality and morbidity in diabetes. This review aims to discuss the major features of DKD, to identify the difficult barrier encountered in developing a therapeutic strategy and to provide a potentially superior novel approach to retard DKD.

RECENT FINDINGS

Renal inflammation and fibrosis are prominent features of DKD. Transforming growth factor beta (TGFβ) with its activity enhanced in DKD plays a key pathological profibrotic role in promoting renal fibrosis. However, TGFβ is a difficult drug target because it has multiple important physiological functions, such as immunomodulation. These physiological functions of TGFβ can be interrupted as a result of complete blockade of the TGFβ pathway if TGFβ is directly targeted, leading to catastrophic side-effects, such as fulminant inflammation. Cell division autoantigen 1 (CDA1) is recently identified as an enhancer of profibrotic TGFβ signaling and inhibitor of anti-inflammatory SIRT1. Renal CDA1 expression is elevated in human DKD as well as in rodent models of DKD. Targeting CDA1, by either genetic approach or pharmacological approach in mice, leads to concurrent attenuation of renal fibrosis and inflammation without any deleterious effects observed.

SUMMARY

Targeting CDA1, instead of directly targeting TGFβ, represents a superior approach to retard DKD.

Marein ameliorates diabetic nephropathy by inhibiting renal sodium glucose transporter 2 and activating the AMPK signaling pathway in db/db mice and high glucose-treated HK-2 cells

Marein, an active component of the Coreopsis tinctoria Nutt. plant, is known to improve diabetic nephropathy (DN). However, its anti-diabetic functions in DN and potential mechanisms remain unclear. The aim of this study was to elucidate the effects and mechanisms of Marein in diabetic db/db mice with DN, and in high glucose-treated HK-2 cells. In vivo, treating diabetic db/db mice with Marein for 12 consecutive weeks restored diabetes-induced hyperglycemia and dyslipidemia, and ameliorated renal function deterioration, glomerulosclerosis, and renal ectopic lipid deposition. Marein exerted renoprotective effects by directly inhibiting renal tubule sodium glucose transporter 2 (SGLT2) expression, and then activating the AMP-activated protein kinase (AMPK)/acetyl CoA carboxylase (ACC)/peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) pathway in db/db mice. Meanwhile, Marein ameliorated fibrosis and inflammation by suppressing the pro-inflammatory factors interleukin-6 (IL-6) and monocyte chemotactic protein-1 (MCP-1), and expression of the extracellular matrix proteins, fibronectin (FN) and collagen 1 (COL1) in diabetic mice. In vitro, MDCK monolayer cells were established to explore the characteristics of Marein transmembrane transport. Marein was found to be absorbed across the membrane at a medium level that involved active transport and this was mediated by SGLTs. In HK-2 cells, Marein decreased uptake of the fluorescent glucose analog, 2-NBDG, by 22 % by inhibiting SGLT2 expression. In high glucose-treated HK-2 cells, Marein decreased SGLT2 expression and increased phosphorylated (p)-AMPK/p-ACC to improve high glucose-induced cellular dysfunction. Furthermore, Marein treatment decreased SGLT2 expression in SGLT2-overexpressing HK-2 cells. In addition, molecular docking and dynamics analysis revealed that SGLT2 was a direct target of Marein. Collectively, our results demonstrated that Marein ameliorates DN by inhibiting renal SGLT2 and activating p-AMPK, suggesting Marein can potentially prevent DN by suppressing renal SGLT2 expression directly.

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.

The Effects of Peritoneal Dialysis Solutions on Peritoneal Host Defense

Conventional peritoneal dialysis fluid (PDF) is a bioincompatible solution owing to the acidic pH, the high glucose concentrations and the associated hyperosmolarity, the high lactate concentrations, and the presence of glucose degradation products (GDPs). This unphysiologic composition adversely affects peritoneal host defense and may thus contribute to the development of PD-related peritonitis. The viability of polymorphonuclear leukocytes, monocytes, peritoneal macrophages, and mesothelial cells is severely depressed in the presence of conventional PDF. In addition, the production of inflammatory cytokines and chemoattractants by these cells is markedly affected by conventional PDF. Further, conventional PDF hampers the recruitment of circulating leukocytes in response to an infectious stimulus. Finally, phagocytosis, respiratory burst, and bacterial killing are markedly lower when polymorphonuclear leukocytes, monocytes, and peritoneal macrophages are exposed to conventional PDF. Although there are a few discrepant results, all major PDF components have been implicated as causative factors. Generally, novel PDF with alternative osmotic agents or with alternative buffers, neutral pH, and low GDP content have much milder inhibitory effects on peritoneal host defense. Clinical studies, however, still need to demonstrate their superiority with respect to the incidence of PD-related peritonitis.

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.

Nephron-specific knockin of the PIKfyve-binding-deficient Vac14L156R mutant results in albuminuria and mesangial expansion

Intracellular trafficking processes play a key role for the establishment and maintenance of membrane surfaces in renal epithelia. Therefore, dysfunctions of these trafficking processes could be key events and important determinants in the onset and progression of diseases. The presence of cellular vacuoles-observed in many histologic analyses of renal diseases-is a macroscopic hint for disturbed intracellular trafficking processes. However, how vacuoles develop and which intracellular pathways are directly affected remain largely unknown. Previous studies showed that in some cases, vacuolization is linked to malfunction of the Vac14 complex. This complex, including the scaffold protein Vac14, the lipid kinase PIKfyve, and its counteracting lipid phosphatase Fig4, regulates intracellular phosphatidylinositol phosphate levels, which in turn, control the maturation of early-into-late endosomes, as well as the processing of autophagosomes into autophagolysosomes. Here, we analyzed the role of Vac14 in mice and observed that the nephron-specific knockin of the PIKfyve-binding-deficient Vac14^L156R mutant led to albuminuria, accompanied by mesangial expansion, increased glomerular size, and an elevated expression of several kidney injury markers. Overexpression of this Vac14 variant in podocytes did not reveal a strong in vivo phenotype, indicating that Vac14-dependent trafficking processes are more important for tubular than for glomerular processes in the kidney. In vitro overexpression of Vac14^L156R in Madin-Darby canine kidney cells had no impact on apico-basal polarity defects but resulted in a faster reassembly of junctional structures after Ca²⁺ depletion and delayed endo- and transcytosis rates. Taken together, our data suggest that increased albuminuria of Vac14^L156R-overexpressing mice is a consequence of a lowered endo- and transcytosis of albumin in renal tubules.

Hyperglycemia-induced Renal P2X7 Receptor Activation Enhances Diabetes-related Injury

Diabetes is a leading cause of renal disease. Glomerular mesangial expansion and fibrosis are hallmarks of diabetic nephropathy and this is thought to be promoted by infiltration of circulating macrophages. Monocyte chemoattractant protein-1 (MCP-1) has been shown to attract macrophages in kidney diseases. P2X7 receptors (P2X7R) are highly expressed on macrophages and are essential components of pro-inflammatory signaling in multiple tissues. Here we show that in diabetic patients, renal P2X7R expression is associated with severe mesangial expansion, impaired glomerular filtration (≤40ml/min/1.73sq.m.), and increased interstitial fibrosis. P2X7R activation enhanced the release of MCP-1 in human mesangial cells cultured under high glucose conditions. In mice, P2X7R-deficiency prevented glomerular macrophage attraction and collagen IV deposition; however, the more severe interstitial inflammation and fibrosis often seen in human diabetic kidney diseases was not modelled. Finally, we demonstrate that a P2X7R inhibitor (AZ11657312) can reduce renal macrophage accrual following the establishment of hyperglycemia in a model of diabetic nephropathy. Collectively these data suggest that P2X7R activation may contribute to the high prevalence of kidney disease found in diabetics.

Differential association of plasma monocyte chemoattractant protein-1 with systemic inflammatory and airway remodeling biomarkers in type-2 diabetic patients with and without asthma

BACKGROUND

Chronic inflammation is a hallmark of type-2 diabetes (T2D) and asthma. Monocyte chemoattractant protein (MCP)-1 or CCL-2 is a key regulator of monocytic infiltration into the sites of inflammation. The changes in systemic MCP-1 levels and its relationship with other inflammatory/immune markers in T2D patients with asthma remain unclear and have been addressed in this study.

METHODS

Plasma samples from 10 asthmatic T2D patients (Group I: BMI = 37.82 ± 9.75 kg/m²), 13 non-asthmatic T2D patients (Group II: BMI = 32.68 ± 4.63 kg/m²), 23 asthma patients without T2D (Group III: BMI = 30.14 ± 6.74 kg/m²), and 25 non-asthmatic non-diabetic controls (Group IV: BMI = 27.99 ± 5.86 kg/m²) were used to measure levels of MCP-1 and multiple cytokine/chemokine biomarkers with bead-based multiplex assays using Luminex technology. IgE/ECP were measured using commercial ELISA kits. Data (mean ± SEM) were compared using unpaired Student's t-test and linear dependence between two variables was assessed by Pearson's correlation coefficient (r) and P ≤ 0.05 was considered as significant.

RESULTS

Plasma MCP-1 levels were significantly higher in Group I (337.95 ± 46.40 pg/mL) as compared with Group II (216.69 ± 17.30 pg/mL), Group III (251.76 ± 19.80 pg/mL), and Group IV (223.52 ± 133.36 pg/mL). MCP-1 showed differential association with tested biomarkers by correlating positively with: (i) IFN-α2, IL-10, fractalkine, and VEGF in T2D patients with asthma; (ii) IL-6 and GRO-α in T2D patients without asthma; (iii) MDC, IP-10, GM-CSF, FGF-2, and PDGF-AA/BB in patients with asthma only; and (iv) FPG and TG in non-asthmatic non-diabetic controls. MCP-1 associated with IL-1RA only in subjects with asthma.

CONCLUSION

The systemic MCP-1 levels were significantly elevated in T2D patients with asthma as compared with those without asthma and/or diabetes while these changes correlated differentially with important biomarkers of inflammation and airway remodeling.

Association of Urinary Biomarkers of Inflammation, Injury, and Fibrosis with Renal Function Decline: The ACCORD Trial

BACKGROUND AND OBJECTIVES

Current measures for predicting renal functional decline in patients with type 2 diabetes with preserved renal function are unsatisfactory, and multiple markers assessing various biologic axes may improve prediction. We examined the association of four biomarker-to-creatinine ratio levels (monocyte chemotactic protein-1, IL-18, kidney injury molecule-1, and YKL-40) with renal outcome.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used a nested case-control design in the Action to Control Cardiovascular Disease Trial by matching 190 participants with ≥40% sustained eGFR decline over the 5-year follow-up period to 190 participants with ≤10% eGFR decline in a 1:1 fashion on key characteristics (age within 5 years, sex, race, baseline albumin-to-creatinine ratio within 20 μg/mg, and baseline eGFR within 10 ml/min per 1.73 m(2)), with ≤10% decline. We used a Mesoscale Multiplex Platform and measured biomarkers in baseline and 24-month specimens, and we examined biomarker associations with outcome using conditional logistic regression.

RESULTS

Baseline and 24-month levels of monocyte chemotactic protein-1-to-creatinine ratio levels were higher for cases versus controls. The highest quartile of baseline monocyte chemotactic protein-1-to-creatinine ratio had fivefold greater odds, and each log increment had 2.27-fold higher odds for outcome (odds ratio, 5.27; 95% confidence interval, 2.19 to 12.71 and odds ratio, 2.27; 95% confidence interval, 1.44 to 3.58, respectively). IL-18-to-creatinine ratio, kidney injury molecule-1-to-creatinine ratio, and YKL-40-to-creatinine ratio were not consistently associated with outcome. C statistic for traditional predictors of eGFR decline was 0.70, which improved significantly to 0.74 with monocyte chemotactic protein-1-to-creatinine ratio.

CONCLUSIONS

Urinary monocyte chemotactic protein-1-to-creatinine ratio concentrations were strongly associated with sustained renal decline in patients with type 2 diabetes with preserved renal function.

Resting Heart Rate Variability, Inflammation, and Insulin Resistance in Overweight and Obese Adolescents

BACKGROUND

The prevalence of obesity is increasing in young people in the United States. Lately, low-grade inflammation is recognized as accompanying obesity, a known risk factor for type 2 diabetes. Autonomic dysfunction is a prominent feature of adult diabetes, but its prevalence in adolescents in prediabetic states or with diabetes risk factors is unknown. We undertook to study obesity, inflammation, insulin resistance, and autonomic dysfunction together in a population of adolescents aged 13-18 years.

METHODS

Subjects gave a blood sample for cytokine analysis and a 5-min resting EKG for analysis of resting heart rate variability. TNF-α, IL-6, c-reactive protein (CRP), MCP-1, and IL-10 were analyzed by enzyme-linked immunosorbent assay, and Fourier Transform was applied to electrocardiographic recordings of R-R intervals for analysis in frequency space. The HOMA calculation was used as an index of insulin sensitivity.

RESULTS

TNF-α, IL-6, CRP, MCP-1, HOMA, and insulin levels, but not serum glucose or IL-10, were higher in the obese subjects. Low-frequency (0.04-0.15 Hz) and high-frequency (0.15-0.4 Hz) fluctuations of R-R intervals were lower in the obese subjects, but the normalized low-frequency power was not different, suggesting proportional reduction in variability in both ranges and impairment of both sympathetic and parasympathetic systems.

CONCLUSIONS

Chronic low-grade inflammation, insulin resistance, and autonomic dysfunction are present at an early age in obese youths; early detection of inflammation may facilitate meaningful lifestyle changes in this high-risk group.

New molecular insights in diabetic nephropathy

Diabetes mellitus represents one of the major causes of functional kidney impairment. The review highlights the most significant steps made over the last decades in understanding the molecular basis of diabetic nephropathy (DN), which may provide reliable biomarkers for early diagnosis and prognosis, along with new molecular targets for personalized medicine. There is an increased interest in developing new therapeutic strategies to slow DN progression for improving patients' quality of life and reducing all-cause morbidity and disease-associated mortality. It is highly important to have a science-based medical attitude when facing diabetic patients with associated comorbidities and risk of rapid evolution toward end-stage renal disease. The data discussed herein were mainly from MEDLINE and PubMed articles published in English from 1990 to 2015 and from up-to-date. The search term was "diabetic nephropathy and oxidative stress".

High glucose induces rat mesangial cells proliferation and MCP-1 expression via ROS-mediated activation of NF-κB pathway, which is inhibited by eleutheroside E

Glomerular hypertrophy and extracellular matrix accumulation are early features of diabetic nephropathy (DN). High glucose-induced oxidative stress is implicated in the etiology of DN. This study aims to investigate the effect of eleutheroside E (EE) on high glucose mediated rat mesangial cells (MCs) proliferation and monocyte chemoattractant protein-1 (MCP-1) expression and the underlying mechanism. MCs proliferation was assessed by MTT assay. Reactive oxygen species (ROS) level and MCP-1 expression were evaluated by ELISA kit. The protein expression of p47, NF-κB p65, p-NF-κB p65, IκBα, p-IκBα, IKKβ and p-IKKβ were determined by Western blot. The results showed that treatment with EE markedly attenuated high glucose induced MCs proliferation and in a dose-dependent manner. Intervention with EE also significantly blocked high glucose induced intracellular ROS production by decreasing NADPH oxidase activity. Meanwhile, EE administration could effectively alleviate the high glucose-stimulated activation of NF-κB, the degradation of IκBα and the expression of MCP-1. These results demonstrate that high glucose enhances MCs proliferation and MCP-1 expression by activating the ROS/NF-κB pathway and can be inhibited by EE. Our findings provide a new perspective for the clinical treatment of DN.

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.

Mesenchymal stem cells transplantation ameliorates glomerular injury in streptozotocin-induced diabetic nephropathy in rats via inhibiting macrophage infiltration

Mesenchymal stem cells (MSCs) treatment has been shown to be effective in diabetic nephropathy (DN). However, the mechanisms involved in the renoprotective effects of MSCs have not been clearly demonstrated. Especially, there was no study on the relationship of MSCs and macrophages in diabetic kidney. To explore the effect of MSCs on macrophages in DN, streptozotocin-induced diabetes animals received no treatment or treatment with MSCs (2×10(6), via tail vein) for two continuous weeks. Eight weeks after treatment, physical, biochemical and morphological parameters were measured. Immunohistochemistry for fibronectin (FN), CollagenI, ED-1, monocyte chemoattractant protein-1 (MCP-1) was performed. Expressions of pro-inflammatory cytokines and hepatocyte growth factor (HGF) at gene level and protein level were determined by real-time reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Blood glucose, urinary albumin excretion, creatinine clearance were significantly reduced after MSCs treatment. The glomerulosclerosis as revealed by periodic acid Schiff stain and expression of FN and CollagenI was also dramatically attenuated. Most importantly, the expression of MCP-1 and the number of infiltrated macrophages in kidney were effectively suppressed by MSCs treatment. The expression of HGF in MSCs group was up-regulated. Meanwhile, the expressions of IL-1β, IL-6 and TNFα were significantly down-regulated by MSCs treatment. Our study suggest that MSCs treatment ameliorates DN via inhibition of MCP-1 expression by secreting HGF, thus reducing macrophages infiltration, down-regulating IL-1β, IL-6, TNFα expression in renal tissue in diabetic rats.

Monocyte Chemoattractant Protein 1 (MCP-1) in obesity and diabetes

Monocyte Chemoattractant Protein-1 (MCP-1) is the first discovered and most extensively studied CC chemokine, and the amount of studies on its role in the etiologies of obesity- and diabetes-related diseases have increased exponentially during the past two decades. This review attempted to provide a panoramic perspective of the history, regulatory mechanisms, functions, and therapeutic strategies of this chemokine. The highlights of this review include the roles of MCP-1 in the development of obesity, diabetes, cardiovascular diseases, insulitis, diabetic nephropathy, and diabetic retinopathy. Therapies that specifically or non-specifically inhibit MCP-1 overproduction have been summarized.

Induction of hemeoxygenase-1 reduces renal oxidative stress and inflammation in diabetic spontaneously hypertensive rats

The renoprotective mechanisms of hemeoxygenase-1 (HO-1) in diabetic nephropathy remain to be investigated. We hypothesize that HO-1 protects the kidney from diabetic insult via lowering renal oxidative stress and inflammation. We used control and diabetic SHR with or without HO-1 inducer cobalt protoporphyrin (CoPP) treatment for 6 weeks. Urinary albumin excretion levels were significantly elevated in diabetic SHR compared to control and CoPP significantly attenuated albumin excretion. Immuno-histochemical analysis revealed an elevation in TGF-β staining together with increased urinary collagen excretion in diabetic versus control SHR, both of which were reduced with CoPP treatment. Renal oxidative stress markers were greater in diabetic SHR and reduced with CoPP treatment. The increase in renal oxidative stress was associated with an elevation in renal inflammation in diabetic SHR. CoPP treatment also significantly attenuated the markers of renal inflammation in diabetic SHR. In vitro inhibition of HO with stannous mesoporphyrin (SnMP) increased glomerular NADPH oxidase activity and inflammation and blocked the anti-oxidant and anti-inflammatory effects of CoPP. These data suggest that the reduction of renal injury in diabetic SHR upon induction of HO-1 are associated with decreased renal oxidative stress and inflammation, implicating the role of HO-1 induction as a future treatment of diabetic nephropathy.

An orally active chemokine receptor CCR2 antagonist prevents glomerulosclerosis and renal failure in type 2 diabetes

The progression of diabetic nephropathy is associated with an infiltration of macrophages expressing different phenotypes. As classically activated chemokine receptor CCR2+ macrophages are thought to drive tissue inflammation and remodeling, we tested whether blocking CCR2 could reduce intrarenal inflammation and prevent glomerulosclerosis in type 2 diabetes. This was achieved with RO5234444, an orally active small-molecule CCR2 antagonist that blocks ligand binding, its internalization, and monocyte chemotaxis. Male type 2 diabetic db/db mice were uninephrectomized to increase glomerular hyperfiltration to accelerate the development of glomerulosclerosis. From 16 weeks until killing at 24 weeks of age, mice were chow fed with or without admixed antagonist to achieve a trough plasma concentration above IC50 for binding in the mouse. CCR2 blockade reduced circulating monocyte levels, but did not affect total leukocyte or neutrophil numbers, and was associated with a reduction in the number of macrophages and apoptotic podocytes in the glomerulus. This treatment resulted in a higher total number of podocytes, less glomerulosclerosis, reduced albuminuria, and a significantly improved glomerular filtration rate. This successful pre-clinical trial suggests that this antagonist may now be ready for testing in humans with the nephropathy of diabetes mellitus.

Novel C-C chemokine receptor 2 antagonists in metabolic disease: a review of recent developments

INTRODUCTION

C-C chemokine ligand 2 (CCL2), also known as monocyte chemoattractant protein-1, and its receptor, C-C chemokine receptor 2 (CCR2), play important roles in various inflammatory diseases. Recently, it has been reported that the CCL2/CCR2 pathway also has an important role in the pathogenesis of metabolic syndrome through its association with obesity and related systemic complications.

AREAS COVERED

This review focuses on the roles of CCR2 in the pathogenesis of adipose tissue inflammation and other organ damage associated with metabolic syndrome, which is still a matter of debate in many studies. It also covers the use of novel CCR2 antagonists as therapies in such conditions.

EXPERT OPINION

There is abundant experimental evidence that the CCL2/CCR2 pathway may be involved in chronic low-grade inflammation of adipose tissue in obesity and related metabolic diseases. Although animal models of diabetes and obesity, as well as human trials, have produced controversial results, there is continued interest in the roles of CCR2 inhibition in metabolic disease. Further identification of the mechanisms for recruitment and activation of phagocytes and determination of the roles of other chemokines are needed. Future study of these fundamental questions will provide a clearer understanding of adipose tissue biology and potential therapeutic targets for treatment of obesity-related metabolic disease, including diabetic nephropathy.

Endothelin receptor A-specific stimulation of glomerular inflammation and injury in a streptozotocin-induced rat model of diabetes

AIMS/HYPOTHESIS

Activation of endothelin receptor-A (ET(A)) increases glomerular permeability to albumin (P(alb)) and elevates pro-inflammatory markers in hyperglycaemic rats.

METHODS

Male Sprague-Dawley rats were given streptozotocin (n = 32) or saline (sham; n = 32). Half of the animals in each group received the ET(A)-selective antagonist, ABT-627 (atrasentan; orally), beginning immediately after hyperglycaemia was confirmed. Glomeruli were isolated by sieving techniques and P(alb) determined from the change in glomerular volume induced by oncotic gradients of albumin. Glomerular nephrin levels were assessed by immunofluorescence, whereas urinary nephrin was measured by immunoassay.

RESULTS

At 3 and 6 weeks after streptozotocin injection, proteinuria was significantly increased compared with sham controls and significantly reduced by ABT-627 treatment. P(alb) was also increased at 3 and 6 weeks post-streptozotocin. ABT-627 had no effect on P(alb) or protein excretion in sham control rats. In glomeruli isolated from hyperglycaemic rats, incubation with BQ-123, a selective ET(A) antagonist, reduced P(alb), whereas BQ-788, a selective endothelin receptor-B antagonist had no effect (n = 6 rats per group, 5-8 glomeruli per rat). Glomerular and plasma content of soluble intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 were significantly increased 6 weeks after streptozotocin (ELISA). ABT-627 attenuated these increases. After 6 weeks of hyperglycaemia, glomerular nephrin content was decreased with a concurrent increase in urinary nephrin excretion. ABT-627 prevented glomerular nephrin loss in hyperglycaemic rats (n = 5-8 rats per group; eight groups).

CONCLUSIONS/INTERPRETATION

These observations support the hypothesis that endothelin-1, via the ET(A) receptor, directly increases P(alb), possibly via nephrin loss, as well as early inflammation in the hyperglycaemic rat.

Multiplex bead analysis of urinary cytokines of type 2 diabetic patients with normo- and microalbuminuria

Renal damage of diabetic patients is linked to chronic low-grade inflammation. The aim of this study was to analyze urinary concentrations of 27 cytokines in type 2 diabetic patients with normo- and microalbuminuria by multiplex bead immunoassay. Urinary levels of IL-8, IP-10, MCP-1, G-CSF, EOTAXIN, RANTES, and TNF-α in microalbuminuric patients were significantly increased compared to those in normoalbuminuric patients (p < 0.05) or controls (p < 0.05). GM-CSF, MIP-1α, and MIP-1β levels were more elevated in microalbuminuric patients than in controls (both p < 0.05). IP-10 and MCP-1 levels were correlated with urinary albumin excretion rate (r = 0.668 and 0.544, both p < 0.01), and estimated glomerular filtration rate (r = -0.454 and -0.418, both p < 0.05). EOTAXIN, GM-CSF, IP-10, MCP-1, and RANTES levels were correlated with HbA1c (r = 0.457, 0.466, 0.678, 0.567, 0.542, respectively, p ≤ 0.01). These results indicate that urinary cytokine determination might be useful for the early diagnosis and management of patients with diabetic nephropathy.

MCP-1: chemoattractant with a role beyond immunity: a review

BACKGROUND

Monocyte Chemoattractant Protein (MCP)-1, a potent monocyte attractant, is a member of the CC chemokine subfamily. MCP-1 exerts its effects through binding to G-protein-coupled receptors on the surface of leukocytes targeted for activation and migration. Role of MCP-1 and its receptor CCR2 in monocyte recruitment during infection or under other inflammatory conditions is well known.

METHOD

A comprehensive literature search was conducted from the websites of the National Library of Medicine (http://www.ncbl.nlm.nih.gov) and Pubmed Central, the US National Library of Medicine's digital archive of life sciences literature (http://www.pubmedcentral.nih.gov/). The data was assessed from books and journals that published relevant articles in this field.

RESULT

Recent and ongoing research indicates the role of MCP-1 in various allergic conditions, immunodeficiency diseases, bone remodelling, and permeability of blood - brain barrier, atherosclerosis, nephropathies and tumors.

CONCLUSION

MCP-1 plays an important role in pathogenesis of various disease states and hence MCP-1 inhibition may have beneficial effects in such conditions.

Fenofibrate attenuates tubulointerstitial fibrosis and inflammation through suppression of nuclear factor-κB and transforming growth factor-β1/Smad3 in diabetic nephropathy

Fibrates, the ligands of peroxisome proliferator-activated receptor-alpha, have been shown to have a renal protective action in diabetic models of renal disease, but the mechanisms underlying this effect are unknown. In the present study, we sought to investigate in greater detail the effect of fenofibrate and its mechanism of action on renal inflammation and tubulointerstitial fibrosis in an animal model of type 2 diabetes mellitus. Twelve-week-old non-diabetic Zucker lean (ZL) and Zucker diabetic fatty (ZD) rats were treated with vehicle or fenofibrate for 10 weeks. mRNA and protein analyses were performed by real-time polymerase chain reaction, Western blot and immunostaining. The diabetic condition of ZD rats was associated with an increase in collagen and alpha-smooth muscle actin accumulation in the kidney, which was significantly reduced by fenofibrate. Chronic treatment of ZD rats with fenofibrate attenuated renal inflammation and tubular injury as evidenced by a decrease in mRNA and protein expression of secreted phosphoprotein-1, monocyte chemotactic protein-1 and kidney injury molecule-1 in the kidneys. Renal interstitial macrophage infiltration was also significantly reduced in the kidneys of fenofibrate-treated diabetic animals. Moreover, renal nuclear factor (NF)-kappaB DNA-binding activity, transforming growth factor (TGF)-beta1 and phospho-Smad3 proteins were significantly higher in ZD animals compared with ZL ones. This increase in NF-kappaB activity, TGF-beta1 expression and Smad3 phosphorylation was greatly attenuated by fenofibrate in the diabetic kidneys. Taken together, fenofibrate suppressed NF-kappaB and TGF-beta1/Smad3 signaling pathways and reduced renal inflammation and tubulointerstitial fibrosis in diabetic ZD animals.

Effect of valsartan on monocyte/endothelial cell activation markers and adiponectin in hypertensive patients with type 2 diabetes mellitus

Angiotensin II receptor blockade has been shown to have a beneficial effect on the angiopathies of hypertension and hyperglycemia in patients with type 2 diabetes. However, the effect of angiotensin II receptor blockade on monocyte and endothelial cell adhesion markers in type 2 diabetes is poorly understood. We investigated the effects of valsartan on these markers in 53 hypertensive patients with and without type 2 diabetes mellitus. Levels of monocyte activation markers (soluble CD14: 2.1+/-0.9 vs. 3.3+/-1.4 microg/ml, p<0.01; monocyte chemotactic peptide: 392+/-94 vs. 489+/-114 pg/ml, p<0.05; and monocyte-derived microparticles: 264+/-98 vs. 511+/-128/microL, p<0.01) and endothelial cell activation markers (soluble E-selectin: 41+/-11 vs. 61+/-20 ng/ml, p<0.001; and soluble vascular cell adhesion molecule-1: 478+/-82 vs. 584+/-101 ng/ml, p<0.01) were significantly increased in hypertensive patients with type 2 diabetes compared to normotensive controls. In addition, the concentrations of adiponectin were significantly decreased in patients with type 2 diabetes (8.1+/-3.1 vs. 5.2+/-2.5 microg/ml, p<0.01). Regardless of the presence of diabetic complications, both systolic and diastolic blood pressures significantly decreased after valsartan administration (valsartan 80 mg/day for 8 weeks). Monocyte and endothelial cell activation markers were decreased significantly in patients with type 2 diabetes after valsartan treatment, but not in non-type 2 diabetic patients. In addition, valsartan alleviated hypoadiponectinemia in hypertensive patients with diabetes (before vs. after: 5.2+/-2.5 vs. 7.6+/-2.7 microg/ml, p<0.001) but did not increase adiponectin levels in the non-diabetic hypertensive group, for which the average adiponectin level was normal prior to treatment. These results suggest angiotensin II receptor blockade (valsartan) may be beneficial as an anti-atherosclerotic therapy in patients with type 2 diabetes in addition to its anti-hypertensive action.

Increased urinary levels of CXCL5, CXCL8 and CXCL9 in patients with Type 2 diabetic nephropathy

CXC chemokines are particularly significant for leukocyte infiltration in inflammatory diseases. Recent reports have shown that inflammation is one of potential pathogenic mechanisms for diabetic nephropathy. However, information on inflammation related with CXC chemokines in human Type 2 diabetic nephropathy still remains scarce. We measured urinary and serum levels of three CXC chemokines, CXCL5, CXCL8 and CXCL9, in 45 Type 2 diabetic patients (DM), 42 primary renal disease (PRD) patients and 22 healthy controls by enzyme-linked immunosorbent assay. Urinary levels of CXCL5, CXCL8 and CXCL9 in DM were significantly elevated compared to those in controls (P<.0001, P<.01, P<.001; respectively). They increased consistent with urinary albumin excretion rate (UAER) and correlated with UAER in partial correlation analyses (r=0.41, P<.01; r=0.40, P<.01; r=0.45, P<.01; respectively). Urinary levels of CXCL5 in DM were significantly interrelated to HbA(1c) (r=0.42, P<.01). On the other hand, PRD showed significant increased levels of urinary CXCL8 and CXCL9 compared to controls (P<.001, P<.01; respectively), and so did PRD as UAER increased. However, there were no significant elevations of urinary levels of CXCL5 in PRD in spite of the increased UAER. We found significant associations of UAER in DM with diabetes duration, 1/serum creatinine, urinary CXCL5 (adjusted R(2)=0.67, P<.0001) or CXCL9 (adjusted R(2)=0.69, P<.0001) in a stepwise multiple regression analysis. These results suggest that these three CXC chemokines may be involved in the progression of human Type 2 diabetic nephropathy and that CXCL5 may be of use for telling diabetic nephropathy from primary renal diseases.

Decreased ADP-ribosyl cyclase activity in peripheral blood mononuclear cells from diabetic patients with nephropathy

AIMS/HYPOTHESIS

ADP-ribosyl-cyclase activity (ADPRCA) of CD38 and other ectoenzymes mainly generate cyclic adenosine 5'diphosphate-(ADP-) ribose (cADPR) as a second messenger in various mammalian cells, including pancreatic beta cells and peripheral blood mononuclear cells (PBMCs). Since PBMCs contribute to the pathogenesis of diabetic nephropathy, ADPRCA of PBMCs could serve as a clinical prognostic marker for diabetic nephropathy. This study aimed to investigate the connection between ADPRCA in PBMCs and diabetic complications.

METHODS

PBMCs from 60 diabetic patients (10 for type 1 and 50 for type 2) and 15 nondiabetic controls were fluorometrically measured for ADPRCA based on the conversion of nicotinamide guanine dinucleotide (NGD(+)) into cyclic GDP-ribose.

RESULTS

ADPRCA negatively correlated with the level of HbA1c (P = .040, R(2) = .073), although ADPRCA showed no significant correlation with gender, age, BMI, blood pressure, level of fasting plasma glucose and lipid levels, as well as type, duration, or medication of diabetes. Interestingly, patients with nephropathy, but not other complications, presented significantly lower ADPRCA than those without nephropathy (P = .0198) and diabetes (P = .0332). ANCOVA analysis adjusted for HbA1c showed no significant correlation between ADPRCA and nephropathy. However, logistic regression analyses revealed that determinants for nephropathy were systolic blood pressure and ADPRCA, not HbA1c.

CONCLUSION/INTERPRETATION

Decreased ADPRCA significantly correlated with diabetic nephropathy. ADPRCA in PBMCs would be an important marker associated with diabetic nephropathy.

MCP-1/CCR2 system is involved in high glucose-induced fibronectin and type IV collagen expression in cultured mesangial cells

Monocyte chemoattractant protein-1 (MCP-1) is a potent chemokine that plays an important role in the recruitment of macrophages. Although previous studies have demonstrated the importance of MCP-1 in the pathogenesis of diabetic nephropathy (DN) in terms of inflammation, the role of MCP-1 and its receptor (C-C chemokine receptor 2; CCR2) in extracellular matrix (ECM) accumulation under diabetic conditions has been largely unexplored. This study was undertaken to investigate the functional role of the MCP-1/CCR2 system in high glucose-induced ECM (fibronectin and type IV collagen) protein expression in cultured mesangial cells (MCs). Mouse MCs were exposed to medium containing 5.6 mM glucose (NG), NG+24.4 mM mannitol (NG+M), or 30 mM glucose (HG) with or without mutant MCP-1 (mMCP-1), CCR2 small interfering (si)RNA, or CCR2 inhibitor (RS102895). To examine the relationship between MCP-1 and transforming growth factor (TGF)-β1, MCs were also treated with TGF-β1 (2 ng/ml) with or without mMCP-1 or CCR2 siRNA. Transient transfection was performed with Lipofectamine 2000 for 24 h. Cell viability was determined by an MTT assay, mouse and human MCP-1 and TGF-β1 levels by ELISA, and CCR2 and ECM protein expression by Western blotting. Transfections of mMCP-1 and CCR2 siRNA increased human MCP-1 levels and inhibited CCR2 expression, respectively. HG-induced ECM protein expression and TGF-β1 levels were significantly attenuated by mMCP-1, CCR2 siRNA, and RS102895 ( P < 0.05). MCP-1 directly increased ECM protein expression, and this increase was inhibited by an anti-TGF-β1 antibody. In addition, TGF-β1-induced ECM protein expression was significantly abrogated by the inhibition of the MCP-1/CCR2 system ( P < 0.05). These results suggest that an interaction between the MCP-1/CCR2 system and TGF-β1 may contribute to ECM accumulation in DN.

High glucose-induced NF-kappaB activation occurs via tyrosine phosphorylation of IkappaBalpha in human glomerular endothelial cells: involvement of Syk tyrosine kinase

Activation of nuclear factor-kappaB (NF-kappaB) occurs by dissociation from IkappaB after serine or tyrosine phosphorylation of IkappaBalpha, but the way of NF-kappaB activation by high glucose has not been defined. High glucose is known to activate NF-kappaB via protein kinase C and reactive oxygen species (ROS). In this study, we investigated how high glucose activates NF-kappaB for CC chemokine ligand 2 production in cultured human glomerular endothelial cells. High glucose increased nuclear translocation of p65 and also increased NF-kappaB DNA binding activity. High glucose-induced NF-kappaB activation occurred without degradation of IkappaBalpha. In agreement with this, there was no increase in serine phosphorylation of IkappaBalpha, while tyrosine phosphorylation of IkappaBalpha was increased by high glucose. High glucose increased the generation of ROS, whereas both alpha-lipoic acid and N-acetylcysteine scavenged the ROS and decreased high glucose-induced tyrosine phosphorylation of IkappaBalpha, nuclear translocation of p65, and NF-kappaB DNA binding activity. Protein kinase C pseudosubstrate inhibited high glucose-induced ROS production, tyrosine phosphorylation of IkappaBalpha, and nuclear translocation of p65. Both BAY 61-3606, a specific inhibitor of Syk protein-tyrosine kinase, and small interfering RNA directed against Syk inhibited high glucose-induced tyrosine phosphorylation of IkappaBalpha as well as p65 nuclear translocation. High glucose increased tyrosine phosphorylation of Syk, while it was inhibited by alpha-lipoic acid and protein kinase C pseudosubstrate. In summary, high glucose-induced NF-kappaB activation occurred not by serine phosphorylation of IkappaBalpha. Our data suggest that ROS-mediated tyrosine phosphorylation of IkappaBalpha is the mechanism for high glucose-induced NF-kappaB activation, and Syk may play a role in tyrosine phosphorylation of IkappaBalpha.

MCP-1/CCL2: a new diagnostic marker and therapeutic target for progressive renal injury in diabetic nephropathy

Despite current therapies, many diabetic patients will suffer from declining renal function in association with progressive kidney inflammation. Recently, animal model studies have demonstrated that kidney macrophage accumulation is a critical factor in the development of diabetic nephropathy. However, specific anti-inflammatory strategies are not yet being considered for the treatment of patients with diabetic renal injury. This review highlights the chemokine monocyte chemoattractant protein-1 (MCP-1)/CC-chemokine ligand 2 as a major promoter of inflammation, renal injury, and fibrosis in diabetic nephropathy. Researchers have found that diabetes induces kidney MCP-1 production and that urine MCP-1 levels can be used to assess renal inflammation in this disease. In addition, genetic deletion and molecular blocking studies in rodents have identified MCP-1 as an important therapeutic target for treating diabetic nephropathy. Evidence also suggests that a polymorphism in the human MCP-1 gene is associated with progressive kidney failure in type 2 diabetes, which may identify patients at higher risk who need additional therapy. These findings provide a strong rationale for developing specific therapies against MCP-1 and inflammation in diabetic nephropathy.

Late onset of Ccl2 blockade with the Spiegelmer mNOX-E36-3'PEG prevents glomerulosclerosis and improves glomerular filtration rate in db/db mice

Diabetic kidney disease is associated with monocyte chemoattractant CC chemokine ligand 2 (CCL2)-dependent glomerular and interstitial macrophage recruitment. In addition, nephropathy is delayed in Ccl2 mutant diabetic mice. However, whether the late onset of therapeutic Ccl2 blockade modulates the progression of advanced diabetic nephropathy remains unknown. We addressed this question by antagonizing Ccl2 with mNOX-E36-3'PEG, an anti-Ccl2 L-enantiomeric RNA aptamer (ie, a Spiegelmer), which binds murine Ccl2 and blocks the recruitment of ex vivo-labeled macrophages to the kidneys of db/db mice with type 2 diabetes. We injected mNOX-E36-3'PEG subcutaneously at a dose of 50 mg/kg three times per week into uninephrectomized (1K) db/db mice with advanced glomerulopathy from 4 to 6 months of age. mNOX-E36-3'PEG reduced the number of glomerular macrophages by 40% compared with nonfunctional (control) Spiegelmer-treated 1K db/db mice. This result was associated with protection from diffuse glomerulosclerosis and significantly improved the glomerular filtration rate. mNOX-E36-3'PEG also reduced renal Ccl2 mRNA and protein expression compared with control Spiegelmer-treated 1K db/db mice of the same age. Together, the late onset of therapeutic Ccl2 blockade, eg, with specific Spiegelmers, offers protection from diffuse glomerulosclerosis in type 2 diabetic db/db mice and, thus, may represent a novel therapeutic strategy for advanced glomerulosclerosis.

Pathogenesis of nonimmune glomerulopathies

Nonimmune glomerulopathies are an area of significant research. This review discusses the development of focal segmental glomerulosclerosis, with particular attention to the role of the podocyte in the initiation of glomerulosclerosis and the contribution to glomerulosclerosis from capillary hypertension and soluble factors such as transforming growth factor beta, platelet-derived growth factor, vascular endothelial growth factor, and angiotensin. The effects of these factors on endothelial and mesangial cells are also discussed. In addition, we review our current understanding of the slit diaphragm (a specialized cell junction found in the kidney), slit diaphragm-associated proteins (including nephrin, podocin, alpha-actinin-4, CD2-associated protein, and transient receptor potential channel 6), and the role of these proteins in glomerular disease. We also discuss the most recent research on the pathogenesis of collapsing glomerulosclerosis, human immunodeficiency virus associated nephropathy, Denys-Drash, diabetic nephropathy, Alport syndrome, and other diseases related to the interaction between the podocyte and the glomerular basement membrane.

Gingival levels of monocyte chemoattractant protein-1 (MCP-1) in diabetes mellitus and periodontitis: an experimental study in rats

The objectives of this study were to investigate and compare the monocyte chemoattractant protein-1 (MCP-1) levels of gingival tissues in diabetes mellitus (DM) and periodontitis and to reveal the effects of MCP-1 on periodontal inflammation and destruction in these diseases. DM was created in 15 rats (group 1) by streptozotocin injection, and periodontitis was obtained by ligature induction in 15 rats (group 2). Fifteen systemically and periodontally healthy rats were used as control (group 3). Gingival MCP-1 levels were measured by enzyme-linked immunosorbent assay (ELISA). Periodontal inflammation was quantified by the inflammatory cell infiltration in the gingival samples, whereas periodontal destruction was assessed by the alveolar bone loss in the experimental regions. MCP-1 concentrations were higher in groups 1 and 2 than in group 3 (p < 0.001). Increased gingival inflammatory cell infiltration and alveolar bone loss were observed in groups 1 and 2 compared to group 3 (p < 0.001). There were positive correlations among the MCP-1 level, gingival inflammatory cell infiltration, and alveolar bone loss in groups 1 and 2 (p < 0.001). Our results suggest that (1) DM may lead to enhanced MCP-1 production in periodontal tissues likewise for periodontitis and (2) there may be a positive correlation between the MCP-1 concentration and diseased nature of periodontium in both diseases.

Recent advancement of understanding pathogenesis of type 1 diabetes and potential relevance to diabetic nephropathy

Type 1 diabetes mellitus is an autoimmune disease characterized by progressive destruction of pancreatic beta cells by genetic and environmental factors which leads to an absolute dependence of insulin for survival and maintenance of health. Although the majority of mechanisms of beta cell destruction remain unclear, many molecules, including proinflammatory cytokines and chemokines such as tumor necrosis factor alpha and monocyte chemoattractant protein-1, are implicated in the development of beta cell damage. Furthermore, beta cell destruction is enhanced by the Th1 and Th17 subsets of CD4+ T cells. In contrast, there are mechanisms involved in the maintenance of peripheral tolerance by regulatory T cells, the function of which depends on the pleiotropic cytokine transforming growth factor beta. Development and progression of renal injuries in patients with diabetic nephropathy are also associated with several growth factors and proinflammatory cytokines, including tumor necrosis factor alpha, insulin-like growth factor-1, monocyte chemoattractant protein-1, vascular endothelial growth factor, and transforming growth factor beta. Although the pathogenic mechanisms underlying type 1 diabetes and diabetic nephropathy are principally different, i.e., autoimmunity and inflammation, some common factors, including susceptibility genes and proinflammatory cytokines, are involved in both mechanisms, including infiltrating cell recruitment, upregulation of other cytokines and chemokines, or apoptosis.

MCP-1 and RANTES polymorphisms in Korean diabetic end-stage renal disease

Macrophage infiltration has been observed in the renal biopsy specimens of diabetic nephropathy (DN), and hyperglycemic state stimulates the renal expression of RANTES (regulated upon activation, normal T-cell expressed and secreted) and MCP- 1 (monocyte chemoattractant protein-1). Upregulation of RANTES and MCP-1 with infiltrating macrophages may play a crucial role in the development and progression of DN. Genetic polymorphisms of RANTES and its receptors were reported to be independent risk factors for DN. We genotyped single nucleotide polymorphism (SNPs) in the MCP-1 G-2518A, CCR2 G46295A, RANTES C-28G and G-403A in 177 diabetic end-stage renal disease (ESRD) patients and 184 patients without renal involvement (controls) in order to investigate the effects of these SNPs on DN in Korean patients with type 2 DM. There were no differences in the frequencies of SNPs and the distribution of haplotypes of RANTES promoter SNPs between two groups. In conclusion, there were no associations of MCP-1, CCR2 and RANTES promoter SNPs with diabetic ESRD in Korean population. Prospective studies with clearly-defined, homogenous cohorts are needed to confirm the effect of these genetic polymorphisms on DN.

Rosiglitazone ameliorates diabetic nephropathy by inhibiting reactive oxygen species and its downstream-signaling pathways

AIM

To study whether rosiglitazone prevents the development of diabetic nephropathy through reduction of reactive oxygen species and its downstream signal transduction pathways.

METHODS

The rats were intraperitoneally injected with streptozotocin to induce diabetes, meanwhile the rats in the therapeutic groups were given rosiglitazone (5 or 20 mg/kg/day) for 4 weeks by intragastric administration. Blood glucose, serum lipid and creatinine, urinary albumin excretion were measured. Malondialdehyde content, the activities of nuclear factor-kappaB (NF-kappaB), antioxidant enzymes including Cu-Zn SOD and GSH-Px in kidney were also measured. In addition, the mRNA and protein expression of MCP-1 were semiquantitatively determined with PT-PCR and immunohistochemical staining respectively.

RESULTS

No significant difference of blood glucose and lipid were found between diabetic rats and rosiglitazone treatment groups. The renal histopathology was improved significantly. The expressions of MCP-1 mRNA and protein, malondialdehyde level and the activity of NF-kappaB were decreased markedly in rats treated with high-dose rosiglitazone, but the activities of renal Cu-Zn SOD and GSH-Px increased significantly.

CONCLUSIONS

Rosiglitazone treatment prevented glomerular injury in diabetic rats, which was closely related with its roles of reducing reactive oxygen species, NF-kappaB activation and MCP-1 expression in the early phase of diabetic nephropathy.

Serum monocyte chemoattractant protein-1 and monocyte adhesion molecules in type 1 diabetic patients with nephropathy

BACKGROUND

Monocyte chemoattractant protein (MCP)-1 is suggested to be implicated in the pathogenesis of diabetic nephropathy by activating and recruiting monocytes to the glomerulus via regulation of adhesion molecule expressions. The aim of this study was to test potential associations between serum concentrations of MCP-1, monocyte expression of Mac-1 and LFA-1 and nephropathy in type 1 diabetes mellitus.

METHODS

Serum MCP-1 levels and expression of monocyte adhesion molecules in 51 type 1 diabetic patients with and without diabetic nephropathy were compared with matched 15 healthy control subjects. Concentrations of serum MCP-1 were determined by enzyme-linked immunosorbent assays whereas monocyte expression of adhesion molecules Mac-1 and LFA-1 was measured by flow cytometry.

RESULTS

Serum MCP-1 levels and expression of Mac-1, but not LFA-1, were significantly higher in diabetic patients compared with controls. The mean serum MCP-1 level was 137.2 +/- 71.4 pg/mL in control patients, whereas it was 246.2 +/- 114.9 pg/ml in diabetic patients (p = 0.002). Serum MCP-1 levels were positively correlated with HbA1c and plasma fasting glucose levels. There was no difference in serum levels of MCP-1 and expression of monocyte adhesion molecules between type 1 diabetic patients with and without diabetic nephropathy.

CONCLUSIONS

In type 1 diabetic patients, the levels of circulating MCP-1 concentration and expression of Mac-1 is mostly influenced by glycemic control rather than the existence of diabetic nephropathy.

Monocyte chemoattractant protein-1--a major contributor to the inflammatory process associated with diabetes

There is evidence that strongly suggests that inflammation plays an important role in diabetes and cardiovascular diseases. The high glucose-induced inflammatory process is characterised by the cooperation of a complex network of inflammatory molecules such as cytokines, adhesion molecules, growth factors, and chemokines. Among the chemokine family, monocyte chemoattractant protein (MCP-1) is a potent chemotactic factor, which is upregulated at sites of inflammation being in control of leukocytes trafficking. Here, we review the current knowledge on MCP-1 and its regulation by high glucose level in vascular cells involved in diabetes-induced accelerated atherosclerosis. The signalling pathways involved in MCP-1 modulation by high glucose, the proximal signalling events that stimulate downstream effects and the role of this chemokine in the pathophysiology of diabetes and its complications, are discussed.

Losartan reduces monocyte chemoattractant protein-1 expression in aortic tissues of 2K1C hypertensive rats

BACKGROUND

Previous study has demonstrated an arterial inflammatory response in aortic tissues in several hypertensive models which can not be fully explained by hemodynamic forces. This study sought to investigate the effect of angiotensin II (Ang II)and its subtype-1 receptor blocker Losartan on the chemokine expression of monocyte chemoattractant protein-1(MCP-1) in aortic tissues of acute stage of 2-kidney-1-clip (2K1C) hypertensive rats.

METHODS

2K1C renovascular hypertension was produced in male Wistar-Kyoto(WKY) rats by placing a silver clip with an internal diameter of 0.2 mm around the left renal artery. The MCP-1 mRNA on aortic wall was detected by in situ hybridization and reverse transcription-polymerase chain reaction(RT-PCR); the levels of Ang II in plasma and aorta were determined by radioimmunoassay. The concentration of MCP-1 in supernatant of cultured endothelial cells (ECV-304) was measured by ELISA.

RESULTS

No MCP-1 was exhibited in aortic wall of normotensive rats both by RT-PCR and in situ hybridization; it would be expressed on the aortic wall of rats in 7 days after 2K1C hypertensive model was formed, especially in intima. The expression of MCP-1 in aortic wall was increased with the duration of hypertension and correlated with local Ang II activity (r=0.594, P=0.02) other than those in plasma, it was decreased obviously after being treated by Losartan for 28 days (optical density of MCP-1/GAPDH ratio: 0, 0.58+/-0.10, 1.14+/-0.09, 1.52+/-0.20, 0.66+/-0.07, respectively, P<0.01). Ang II had increased the expression of MCP-1 in endothelial cells; the highest levels had been performed at 1x10(-7)mol/l Ang II or after 4 h, respectively; and losartan markedly reduced the expression of MCP-1.

CONCLUSIONS

The expression of MCP-1 significantly increases in aortic tissues of the acute stage 2K1C hypertensive rats and is decreased markedly by treatment of losartan. These findings imply Ang II may be involved in facilitating MCP-1 production in hypertension, and may provide a molecular link between hypertension and the development of atherosclerosis.

Association between circulating monocyte chemoattractant protein-1 and urinary albumin excretion in nonobese Type 2 diabetic patients

In 70 nonobese inpatients with Type 2 diabetes [body mass index (BMI): 24.0+/-4.4 kg/m(2)], we examined circulating monocyte chemoattractant protein (MCP) -1 as a candidate marker of atherosclerosis by comparison with established markers: serum high-sensitivity C-reactive protein (hsCRP), plasma fibrinogen, and combined carotid artery intimal-medial thickness (IMT). In addition, an association was sought between circulating MCP-1 and urinary albumin excretion (UAE), reflecting diabetic renal microangiopathy. Serum MCP-1 was determined by enzyme-linked immunosorbent assay (ELISA). Patients were grouped by UAE: normoalbuminuria, below 30 mg/g of creatinine (Cr); microalbuminuria, 30 to 300 mg/g Cr; or macroalbuminuria, over 300 mg/g Cr. Serum MCP-1 for all participants, men, and women was 280.0+/-78.9, 269.0+/-68.8, and 294.9+/-87.9 pg/ml, respectively, showing no difference between genders. No correlation was noted between MCP-1 and hsCRP, fibrinogen, or carotid artery IMT. No correlation of MCP-1 was observed with age, duration of diabetes, fasting plasma glucose (FPG), hemoglobin (Hb) A(1C), BMI, diastolic blood pressure (DBP), or serum lipid concentrations, but significant correlations were found with systolic blood pressure (SBP; R=.2723, P=.0225) and with log(10)-transformed (log) UAE (R=.3343, P=.0047). Patients with macroalbuminuria had significant higher circulating MCP-1 than did those with normo- or microalbuminuria (P=.0063 and P=.0188, respectively). By stepwise regression analysis, only log UAE independently predicted serum MCP-1 (beta=.3700, P=.0020). Thus, in nonobese Type 2 diabetic patients, MCP-1 might not be a marker of atherosclerosis and might be influenced significantly by diabetic nephropathy.

MCP-1 and MIP-2 expression and production in BB diabetic rat: effect of chronic hypoxia

Type 1 (insulin-dependent) diabetes mellitus is an autoimmune disease characterized by the failure to synthesize or secrete insulin, and diabetics are likely to suffer complications that include kidney and heart disease, as well as loss of sight, angiopathy, tissue hypoxia, reduction in organ blood flow, impaired wound healing, respiratory infections, arteriosclerosis, etc., thus diabetes very closely resembles a state of chronic hypoxia. It is now well recognized that hypoxia is an important environmental stimulus capable of modulating the expression of many genes involved in energy metabolism. The diabetic metabolic stress resulting from impaired energy metabolism, which produce altered production of inflammatory mediators, may increase the risk of oxidative injury. The aim was to investigate whether production of MIP-2 and MCP-1 are implicated in the pathogenesis of diabetes, and if the regulatory effects of these chemokines are affected by hypoxia. Two groups of rats, diabetic and non-diabetic, were kept in normoxic room air conditions or subjected to chronic hypoxia. Expression and production of chemokines were measured by RT-PCR and ELISA assay. In diabetic rats, we found a marked increase of MCP-1 when compared with non-diabetic rats (783.5+/- 49 versus 461.9 +/- 27), while no significant differences were detected for MIP-2 levels. Hypoxia selectively modulated chemokines production, since MCP-1 expression and production was up-regulated in the diabetic groups (783.5+/- 49 versus 461.9+/- 27), but down-regulated MIP-2 expression and production (87.8+/- 23 versus 522.1+/- 72). Our data point to MCP-1 and MIP-2 as important components in the pathophysiology of diabetes, and hypoxia is an important and potent environmental stimulus capable of modulating the expression and production of these chemokines.

Leukocyte recruitment and vascular injury in diabetic nephropathy

Different types of activated leukocytes play a crucial role in the pathogenesis of most kidney diseases from acute to chronic stages; however, diabetic nephropathy was not considered an inflammatory disease in the past. This view is changing now because there is a growing body of evidence implicating inflammatory cells at every stage of diabetic nephropathy. Renal tissue macrophages, T cells, and neutrophils produce various reactive oxygen species, proinflammatory cytokines, metalloproteinases, and growth factors, which modulate the local response and increase inflammation within the diabetic kidney. Although the precise mechanisms that direct leukocyte homing into renal tissues are not fully identified, it has been reported that intercellular adhesion molecule-1 and the chemokines CCL2 and CX3CL1 probably are involved in leukocyte migration in diabetic nephropathy. This review focuses on the molecular mechanisms of leukocyte recruitment into the diabetic kidney and the involvement of immigrated immune cells in the damage to renal tissues.

Protein Kinase C β Inhibitor LY333531 Attenuates Intercellular Adhesion Molecule-1 and Monocyte Chemotactic Protein-1 Expression in the Kidney in Diabetic Rats

In vitro studies have shown that activation of protein kinase C (PKC) is a key mediator of intercellular adhesion molecule-1 (ICAM-1) and monocyte chemoattractant protein-1 (MCP-1) in a range of cell types and in response to high glucose, however, its role in the in vivo setting has not been clearly delineated. Streptozotocin-induced diabetic rats were treated with the PKC-beta isoform inhibitor LY333531 for 8 weeks. LY333531 treatment significantly attenuated increased urinary albumin excretion rate and glomerular volume and tubulointerstitial injury index as well as elevated PKC activity and PKC-beta protein expression in the kidney. Level of malondialdehyde was markedly higher and antioxidant enzyme activity such as superoxide diamutase and catalase as well as glutathione peroxidase were significantly lower in the kidney from diabetic rats than that of the control group. LY333531 administration could remit these changes. Increased macrophages recruitment as well as ICAM-1 and MCP-1 protein expression in the kidney were significantly inhibited by LY333531 in diabetic rats. It is concluded that mechanism of renoprotection of LY333531 may be correlated, at least partly, with suppression of increased macrophages recruitment and overexpression of ICAM-1 and MCP-1 in diabetic rats.

Prevention of early renal injury by mycophenolate mofetil and its mechanism in experimental diabetes

Previously it was shown that treatment with mycophenolate mofetil (MMF) attenuated renal inflammation and glomerular injury in a model of diabetes. However, the mechanism involved in the renoprotective effects of MMF in experimental diabetes has not been clearly delineated. Diabetes was induced by injection of streptozotocin (STZ) after uninephrectomy. Diabetic animals received no treatment or treatment with MMF (10 mg/kg once daily by gastric gavage) for 8 weeks, non-diabetic rats served as controls. Level of malondialdehyde (MDA) in renal tissue and urine as well as the activity of antioxidant enzymes (AOE) in renal tissue was determined. Renal injury was evaluated. Immunohistochemistry for ED-1 macrophages marker, intercellular adhesion molecule-1 (ICAM-1) and monocyte chemoattractant protein-1 (MCP-1) was performed. Expression of transforming growth factor (TGF)-beta1 protein was determined by Western blotting analysis. Treatment with MMF had no effect on blood glucose level, but did prevent increased urinary albumin excretion and glomerular damage in diabetic rats. Oxidative stress was reduced by MMF treatment, as indicated by a reduction in MDA level in renal tissue and urine. Activity of AOE such as glutathione peroxidase (GSH-PX) was markedly elevated while superoxide dismutase (SOD) and catalase (CAT) were not changed by MMF treatment. In diabetic animals receiving no treatment, there were increases in ED-1-positive cells, ICAM-1 expression and MCP-1 expression in glomeruli and tubulointerstitium, which were effectively suppressed by MMF treatment. Western blotting analysis showed that the expression of TGF-beta1 protein was increased by 1.92-fold in renal tissue in diabetic rats, and MMF treatment significantly reduced the increased expression of TGF-beta1 protein by 45%. Our data suggest that MMF treatment ameliorates early renal injury via the inhibition of oxidative stress and overexpression of ICAM-1, MCP-1 and TGF-beta1 in renal tissue in diabetic rats.

High glucose and angiotensin II increase β1 integrin and integrin-linked kinase synthesis in cultured mouse podocytes

Alterations of integrin alpha3beta1 may play a role in the development of diabetic nephropathy. We have investigated the effects of high glucose and angiotensin II on the expression of integrin alpha3 and beta1, and whether these changes are associated with integrin-linked kinase (ILK) in cultured mouse podocytes. Integrin beta1 and ILK mRNA expression and protein production were rapidly up-regulated in a dose-dependent manner by high glucose and angiotensin II stimulation. ILK mRNA levels in the mouse podocytes exposed to 30 mmol/l glucose were 1.66, 1.89, and 1.28 times higher than those in control cells at 6, 24, and 72 h exposure, respectively. ILK mRNA levels in mouse podocytes exposed to 1 nM, 10 nM, and 100 nM angiotensin II for 6 h were 1.38, 1.55, and 1.93 times higher, respectively, than those in control cells. Angiotensin-II-induced integrin beta1 and ILK mRNA expression was significantly inhibited by treatment with losartan (100 muM). In addition, the up-regulation of ILK synthesis induced by these stimuli was related to beta1 integrin synthesis and increased ILK kinase activity. Cell adhesion assay displayed inhibitory effects when podocytes were exposed to high concentrations of angiotensin II. Interestingly, glucose and angiotensin II stimulation induced shrinkage of the cell body and elongation of the podocyte processes, a phenotype similar to that of immature podocytes. In addition, beta1 integrin showed higher levels of staining on both the cell membranes and the cell-cell contact areas. Thus, high glucose and angiotensin II may affect the regulation of the integrin-ILK system in podocytes; this system may therefore play a role in the pathogenesis of diabetic nephropathy and other renal diseases affecting podocytes.

Long-term treatment with nifedipine modulates procoagulant marker and C-C chemokine in hypertensive patients with type 2 diabetes mellitus

In type 2 diabetes mellitus, there is increased risk of nephropathy and cardiovascular complications and the incidence of renal failure increases in advanced stages of the disease. Nifedipine, a dihydropyridine-type calcium antagonist, improves endothelial function in hypercholesterolemia by enhancing nitric oxide function, and increases endothelial nitric oxide bioavailability by antioxidative mechanisms. We administered nifedipine, 50 mg/day, to the hypertensive patients for 12 months. There were no other changes in any of the patient's pharmacologic regimen during nifedipine treatment. Clinical and biochemical data obtained before and after nifedipine administration were compared. All markers were measured by ELISA. The levels of platelet activation markers (CD62P, CD63, PAC-1, and Annexin V), microparticles (PDMP and MDMP), RANTES and soluble adhesion markers (sP-selectin and sVCAM-1) differed in the control group and the hypertension group. The levels of these markers were also different in hypertensive patients with and without type 2 diabetes but were unchanged in patients without diabetes in comparison to the control group. However, the concentrations of MDMPs, chemokines, and soluble adhesion markers in hypertensive patients without type 2 diabetes decreased significantly following nifedipine treatment, although the level of RANTES was unchanged. Systolic blood pressure correlated with CD62P, CD63, annexin V, and RANTES levels, and diastolic blood pressure with CD62P and annexin V levels. The effect of nifedipine on platelet activation markers and C-C chemokines in the present study indicates potential effectiveness of calcium antagonist therapy for hypertensive patients with type 2 diabetes.