Aberrant cytokines/chemokines production correlate with proteinuria in patients with overt diabetic nephropathy

Diabetic nephropathy: traditional to proteomic markers

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes and it is defined as a rise in the urinary albumin excretion (UAE) rate and abnormal renal function. Currently, changes in albuminuria are considered a hallmark of onset or progression of DN. However, some patients with diabetes have advanced renal pathological changes and progressive kidney function decline even if urinary albumin levels are in the normal range, indicating that albuminuria is not the perfect marker for the early detection of DN. The present article provides an overview of the literature reporting some relevant biomarkers that have been found to be associated with DN and that potentially may be used to predict the onset and/or monitor the progression of nephropathy. In particular, biomarkers of renal damage, inflammation, and oxidative stress may be useful tools for detection at an early stage or prediction of DN. Proteomic-based biomarker discovery represents a novel strategy to improve diagnosis, prognosis and treatment of DN; however, proteomics-based approaches are not yet available in most of the clinical chemistry laboratories. The use of a panel with a combination of biomarkers instead of urinary albumin alone seems to be an interesting approach for early detection of DN, including markers of glomerular damage (e.g., albumin), tubular damage (e.g., NAG and KIM-1), inflammation (e.g., TNF-α) and oxidative stress (e.g., 8-OHdG) because these mechanisms contribute to the development and outcomes of this disease.

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.

Inflammation and oxidative stress in diabetic nephropathy: new insights on its inhibition as new therapeutic targets

Diabetes and insulin resistance can greatly increase microvascular complications of diabetes including diabetic nephropathy (DN). Hyperglycemic control in diabetes is key to preventing the development and progression of DN. However, it is clinically very difficult to achieve normal glucose control in individual diabetic patients. Many factors are known to contribute to the development of DN. These include diet, age, lifestyle, or obesity. Further, inflammatory- or oxidative-stress-induced basis for DN has been gaining interest. Although anti-inflammatory or antioxidant drugs can show benefits in rodent models of DN, negative evidence from large clinical studies indicates that more effective anti-inflammatory and antioxidant drugs need to be studied to clear this question. In addition, our recent report showed that potential endogenous protective factors could decrease inflammation and oxidative stress, showing great promise for the treatment of DN.

Gene expression dynamics during diabetic periodontitis

Diabetes impairs the resolution of periodontal inflammation. We explored pathways altered by inflammation in the diabetic periodontium by using ligatures to induce periodontitis in type-2 diabetic Goto-Kakizaki rats. Ligatures were removed after 7 days, and rats were then treated with TNF inhibitor (pegsunercept) or vehicle alone and euthanized 4 days later. RNA was extracted from periodontal tissue, examined by mRNA profiling, and further analyzed by functional criteria. We found that 1,754 genes were significantly up-regulated and 1,243 were down-regulated by pegsunercept (p < 0.05). Functional analysis revealed up-regulation of neuron-associated and retina-associated gene clusters as well as those related to cell activity and signaling. Others were down-regulated by TNF inhibition and included genes associated with host defense, apoptosis, cell signaling and activity, and coagulation/hemostasis/complement. For selected genes, findings with microarray and rt-PCR agreed. PPAR-α was investigated further by immunohistochemistry due to its anti-inflammatory function and was found to be up-regulated in the gingiva during the resolution of periodontal inflammation and suppressed by diabetes. The results indicate that diabetes-enhanced inflammation both up- and down-regulates genes involved in cellular activity and cell signaling, while it predominantly up-regulates genes involved in the host response, apoptosis, and coagulation/homeostasis/complement and down-regulates mRNA levels of neuron, retina, and energy/metabolism-associated genes.

Urinary markers of renal inflammation in adolescents with Type 1 diabetes mellitus and normoalbuminuria

AIMS

Patients with the highest albumin:creatinine ratio within the normal range are at an increased risk for developing microalbuminuria. The mechanistic basis for this is unknown, but may be related to renal inflammation. Our goal was to characterize the urinary excretion of cytokines/chemokines in normoalbuminuric adolescents with Type 1 diabetes to determine whether higher range normoalbuminuria is associated with evidence of renal inflammation.

METHODS

Forty-two urinary cytokines/chemokines were measured in subjects who were screened for the Adolescent Type 1 Diabetes Cardio-Renal Intervention Trial. Urinary cytokines/chemokines were compared across low (n = 50), middle (n = 50) or high (n = 50) albumin:creatinine ratio tertile groups.

RESULTS

At baseline, participants in the upper tertile were younger and had shorter diabetes duration compared with the other groups. Other clinical characteristics were similar. Urinary levels of interleukin 6, interleukin 8, platelet-derived growth factor-AA and RANTES differed across albumin:creatinine ratio tertiles, with higher values in patients in the middle and high tertiles compared with the lower tertile (ANCOVA P ≤ 0.01).

CONCLUSIONS

Within the normal albumin:creatinine ratio range, higher urinary albumin excretion is associated with elevated urinary levels of inflammatory markers. Ultimately, this may provide mechanistic insights into disease pathophysiology and stratify the risk of nephropathy in Type 1 diabetes.

Pre-clinical markers for diagnosis of diabetic nephropathy in patients with type 1 diabetes mellitus

Due to progressive nature of diabetic nephropathy (DN) and limited effectiveness of therapeutic efforts at clinically overt stages, diagnosisof pre-clinical (and, therefore, potentially reversible) DN is especially important. To date, however, test for microalbuminuriaremains the only technique applicable for early diagnostics of DN. Current review addresses search for potential markers of pre-clinical stage of DN in patients with type 1 diabetes mellitus and embracesdata from latest experimental and clinical studies in this area.

Cytokines in diabetic nephropathy

Diabetic nephropathy (DN), the most common cause of end-stage renal disease (ESRD), is increasingly considered an inflammatory process characterized by leukocyte infiltration at every stage of renal involvement. Cytokines act as pleiotropic polypeptides that regulate inflammatory and immune responses, providing important signals in the pathologic and physiologic processes. Inflammation and activation of the immune system are closely involved in the pathogenesis of diabetes and its microvascular complications. Proinflammatory, Th1, Th2, and Th17 cytokines, as well as TGF-beta, all take part in the development and progression of DN. Gene polymorphism of cytokines and their receptors may have functional variations and can be applied to predict the susceptibility and progression to DN. Improved knowledge on recognizing cytokines as significant pathogenic mediators in DN leaves opens the possibility of new potential therapeutic agents for future clinical treatments.

Role of T cells in type 2 diabetic nephropathy

Type 2 diabetic nephropathy (DN) is the most common cause of end-stage renal disease and is increasingly considered as an inflammatory disease characterized by leukocyte infiltration at every stage of renal involvement. Inflammation and activation of the immune system are closely involved in the pathogenesis of diabetes and its microvascular complications. Macrophage has been well recognized to play an important role in type 2 DN, leukocyte infiltration, and participated in process of DN, as was proposed recently. Th1, Th2, Th17, T reg, and cytotoxic T cells are involved in the development and progression of DN. The purpose of this review is to assemble current information concerning the role of T cells in the development and progression of type 2 DN. Specific emphasis is placed on the potential interaction and contribution of the T cells to renal damage. The therapeutic strategies involving T cells in the treatment of type 2 DN are also reviewed. Improving knowledge of the recognition of T cells as significant pathogenic mediators in DN reinforces the possibility of new potential therapeutic targets translated into future clinical treatments.

A risk-analysis approach to the evaluation of analytical quality

BACKGROUND

Setting specifications for analytical quality is always difficult. The risk-management approach might be a way to do so. In this approach, the definition of the required analytical quality is based on the evaluation of patient risk. Risk derives from the probability of error and from the damage that such an error might cause.

METHODS

Eight Italian laboratories took part in this experiment. Measurements of glucose and total calcium were taken as examples. Analytical quality was evaluated using a specific ring trial with a frozen serum pool and by means of internal quality-control data. The total allowable error was defined according to biological variation specifications. The probability of error was extracted from the imprecision and comparative bias data of each laboratory. The damage caused by a wrong result was evaluated using the absolute probability judgment approach.

RESULTS

According to the iso-risk plots (standardized hyperboles on a graph where the x-axis represents damage and the y-axis represents probability) for glucose, all the laboratories were working with an analytical quality that guaranteed low risk for patients. On the contrary, for total calcium none of the laboratories exhibited sufficient quality to guarantee low risk for patients, the presence of bias being the most relevant problem.

CONCLUSIONS

The results seem to demonstrate the applicability of the risk approach to the analytical phase, indicating a new possible way to define analytical quality targets.

Urinary monocyte chemoattractant protein-1 in renal disease

Monocyte chemoattractant protein-1 (MCP-1/CCL2) has a critical role in the development of various renal diseases. Data from disease specific experimental animal models and clinical studies confirm that MCP-1 plays an important part in the pathogenesis of renal diseases. The action of MCP-1 in these studies has been shown to be more complex than the traditional concept of monocyte/macrophage recruitment to the inflammatory site. MCP-1 is expressed in renal tissues and it is detectable in urine of patients with a variety of renal diseases. Measurement of urinary levels of MCP-1 can provide valuable information not only for the diagnosis of active renal disease, but also for monitoring of response to therapy. Urinary MCP-1 measurement can provide help with evaluation of the prognosis in various renal diseases. Furthermore, selective targeting of MCP-1 could be an effective treatment in suppressing a number of renal diseases as blocking MCP-1 has already been shown to ameliorate renal diseases in experimental animal models. The advantage of measuring urinary MCP-1 rather than the conventional markers must now be validated using a larger cohort of patients in different renal diseases. Also the therapeutic potential of MCP-1 targeting agents needs to be investigated in clinical studies.

Isoangustone A suppresses mesangial fibrosis and inflammation in human renal mesangial cells

Development of diabetic nephropathy with fibrosis is associated with hypereglycemia-linked inflammation. Increased levels of proinflammatory factors have been found in diabetic patients with nephropathy. The present study was to test the hypothesis that isoangustone A, a novel compound present in licorice, can inhibit renal fibrosis and inflammation inflamed by high glucose (HG) in human mesangial cells through disturbing transforming growth factor β (TGF- β) and nuclear facor κB (NF- κB) pathways. Serum-starved mesangial cells were cultured in 33 mmol/L glucose media. Cells were treated with 1–20 μmol/L isoangustone A isolated from Glycyrrhiza uralensis licorice for three days. Exposure of cells to HG elevated connective tissue growth factor and collagen production, which was dose-dependently reversed by isoangustone A. Isoangustone A boosted HG-plummeted membrane type matrix metalloproteinase (MMP)-1 expression and diminished HG-elevated tissue inhibitor of MMP-2 expression. HG activated mesangial TGF- β1-SMAD-responsive signaling, which was repealed by ≥10 μmol/L isoangustone A. Furthermore, HG upregulated intracellular cell adhesion molecule-1 (ICAM-1) level and monocyte chemoattractant protein-1 (MCP-1) mRNA expression, and such increases were dose-dependently suppressed by isoangustone A most likely through hampering TGF- β signaling pathways. Blockade of NF- κB signaling appeared to be responsible for attenuating HG-triggered induction of ICAM-1 and MCP-1. Our findings provide the first evidence that isoangustone A dampens mesangial sclerosis associated with inflammation in response to HG through hindering TGF- β and NF- κB signaling.

Hydrochloride pioglitazone decreases urinary cytokines excretion in type 2 diabetes

OBJECTIVE

To observe the effects of hydrochloride pioglitazone on urinary cytokine excretion in type 2 diabetes and to explore its possible reno-protective mechanisms.

DESIGN

Subjects and Methods. Ninety-eight patients with type 2 diabetes and a fasting blood glucose (FBG) levels between 7.0 and 13.0 mm and glycated haemoglobin A1c (HbA1c) ≥ 7.0% were assigned randomly to receive either the pioglitazone (DP group) or a sulphonylurea (DS group). Another 49 healthy individuals were chosen as normal controls (group NC). At the start of the study and after 12 weeks of treatment, urinary cytokines including monocyte chemoattractant protein-1 (MCP-1), transforming growth factor-β1 (TGF-β1) and vascular endothelial growth factor were measured and were expressed as a ratio of urinary creatinine excretion. Urinary albumin/creatinine ratio, FBG and HbA1c were determined at the same time.

RESULTS

The excretion of each urinary cytokine, corrected for urinary creatinine, was significantly increased in both groups of patients with diabetes, compared with normal controls, and after a 12-week treatment were significantly decreased by both therapies but the effect of pioglitazone was statistically greater than with sulphonylureas. Urinary albumin/UCr and both systolic and diastolic blood pressure were decreased significantly by pioglitazone (P < 0.01 or P < 0.05) but not by sulphonylurea treatment (P < 0.05), while there was no significant difference in FBG or HbA1c between two groups. There was a positive correlation between the excretion of cytokines and urinary albumin /UCr (all P < 0.01).

CONCLUSIONS

This study indicates that pioglitazone reduces urinary albumin excretion by a mechanism that is at least partly independent of blood sugar control. The correlation of urinary albumin excretion with improvement in urinary cytokines suggests that this reno-protective effect of piogliazone in diabetes may be related to local reduction in cytokine activity within the kidney.

High-molecular weight hyaluronan reduced renal PKC activation in genetically diabetic mice

The cluster determinant (CD44) seems to play a key role in tissues injured by diabetes type 2. CD44 stimulation activates the protein kinase C (PKC) family which in turn activates the transcriptional nuclear factor kappa B (NF-κB) responsible for the expression of the inflammation mediators such as tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), interleukin-18 (IL-18), inducible nitric oxide synthase (iNOS), and matrix metalloproteinases (MMPs). Regulation of CD44 interaction with its ligands depends greatly upon PKC. We investigated the effect of the treatment with high-molecular weight hyaluronan (HA) on diabetic nephropathy in genetically diabetic mice. BKS.Cg-m+/+Lepr(db) mice had elevated plasma insulin from 15 days of age and high blood sugar levels at 4 weeks. The severe nephropathy that developed was characterized by a marked increased in CD44 receptors, protein kinase C betaI, betaII, and epsilon (PKC(βI), PKC(βII), and PKCε) mRNA expression and the related protein products in kidney tissue. High levels of mRNA and related protein levels were also detected in the damaged kidney for NF-κB, TNF-α, IL-6, IL-18, MMP-7, and iNOS. Chronic daily administration of high-molecular mass HA for 2 weeks significantly reduced CD44, PKC(βI), PKC(βII), and PKCα gene expression and the related protein production in kidney tissue and TNF-α, IL-6, IL-18, MMP-7, and iNOS expression and levels also decreased. Histological analysis confirmed the biochemical data. However, blood parameters of diabetes were unchanged. These results suggest that the CD44 and PKC play an important role in diabetes and interaction of high-molecular weight HA with these proteins may reduce inflammation and secondary pathologies due to this disease.

Association of interleukin-10 polymorphisms with cytokines in type 2 diabetic nephropathy

OBJECTIVE

Interleukin-10 (IL-10) polymorphic variants are linked with cytokine production and are involved in many chronic inflammatory diseases, including type 2 diabetes mellitus (T2DM). We investigated the hypothesis that IL-10 promoter polymorphisms may be associated with cytokine expressions involved in the progression of diabetic nephropathy (DN).

STUDY DESIGN

A total of 72 Taiwanese subjects were included in this study; along with a control group, patients had a diagnosis of DN lasting ≥2 years, and patients had a diagnosis of T2DM with normal renal functions lasting ≥5 years. Their IL-10 and tumor necrosis factor-α (TNF-α) genotyping and association of blood chemistry, plasma IL-10, TNF-α, and monocyte chemoattract protein-1 (MCP-1), and urinary MCP-1 were investigated.

RESULTS

The IL-10-(-592) genotype exhibited significant association with cytokine expressions in DN: significantly higher TNF-α and lower plasma IL-10 levels were observed in IL-10-(-592)AA, whereas a higher urine MCP-1 level was found in Taiwanese patients with the IL-10-(-592)CC genotype.

CONCLUSIONS

IL-10-(-592) promoter polymorphisms may influence IL-10 and MCP-1 production, which may be an indicator of nephropathy risk in Taiwanese T2DM patients.