Urinary concentration of transforming growth factor-beta-inducible gene-h3(beta ig-h3) in patients with Type 2 diabetes mellitus

FN1 and TGFBI are key biomarkers of macrophage immune injury in diabetic kidney disease

The pathogenesis of diabetic kidney disease (DKD) is complex, and the existing treatment methods cannot control disease progression well. Macrophages play an important role in the development of DKD. This study aimed to search for biomarkers involved in immune injury induced by macrophages in DKD. The GSE96804 dataset was downloaded and analyzed by the CIBERSORT algorithm to understand the differential infiltration of macrophages between DKD and normal controls. Weighted gene co-expression network analysis was used to explore the correlation between gene expression modules and macrophages in renal tissue of DKD patients. Protein-protein interaction network and machine learning algorithm were used to screen the hub genes in the key modules. Subsequently, the GSE30528 dataset was used to further validate the expression of hub genes and analyze the diagnostic effect by the receiver operating characteristic curve. The clinical data were applied to explore the prognostic significance of hub genes. CIBERSORT analysis showed that macrophages increased significantly in DKD renal tissue samples. A total of ten modules were generated by weighted gene co-expression network analysis, of which the blue module was closely associated with macrophages. The blue module mainly played an important role in biological processes such as immune response and fibrosis. Fibronectin 1 (FN1) and transforming growth factor beta induced (TGFBI) were identified as hub genes of DKD patients. Receiver operating characteristic curve analysis was performed in the test cohort: FN1 and TGFBI had larger area under the curve values (0.99 and 0.88, respectively). Clinical validation showed that 2 hub genes were negatively correlated with the estimated glomerular filtration rate in DKD patients. In addition, FN1 and TGFBI showed a strong positive correlation with macrophage alternative activation. FN1 and TGFBI are promising biomarkers for the diagnosis and treatment of DKD patients, which may participate in immune response and fibrosis induced by macrophages.

Identification and Verification of Diagnostic Biomarkers for Glomerular Injury in Diabetic Nephropathy Based on Machine Learning Algorithms

Diabetic nephropathy (DN) is regarded as the leading cause of end-stage renal disease worldwide and lacks novel therapeutic targets. To screen and verify special biomarkers for glomerular injury in patients with DN, fifteen datasets were retrieved from the Gene Expression Omnibus (GEO) database, correspondingly divided into training and testing cohorts and then merged. Using the limma package, 140 differentially expressed genes (DEGs) were screened out between 81 glomerular DN samples and 41 normal ones from the training cohort. With the help of the ConsensusClusterPlus and WGCNA packages, the 81 glomerular DN samples were distinctly divided into two subclusters, and two highly associated modules were identified. By using machine learning algorithms (LASSO, RF, and SVM-RFE) and the Venn diagram, two overlapping genes (PRKAR2B and TGFBI) were finally determined as potential biomarkers, which were further validated in external testing datasets and the HFD/STZ-induced mouse models. Based on the biomarkers, the diagnostic model was developed with reliable predictive ability for diabetic glomerular injury. Enrichment analyses indicated the apparent abnormal immune status in patients with DN, and the two biomarkers played an important role in the immune microenvironment. The identified biomarkers demonstrated a meaningful correlation between the immune cells' infiltration and renal function. In conclusion, two robust genes were identified as diagnostic biomarkers and may serve as potential targets for therapeutics of DN, which were closely associated with multiple immune cells.

Role of Urinary Transforming Growth Factor Beta-B1 and Monocyte Chemotactic Protein-1 as Prognostic Biomarkers in Posterior Urethral Valve

Background:

Posterior Urethral Valves (PUV) are the most common cause of congenital LUT obstruction in males. Biomarkers of glomerular or tubular injury may be of particular value in predicting the need for surgical intervention or in tracing progression of chronic kidney disease. Measurement of biomarker in urine is relatively easy.

Aim:

To evaluate the changes in values of urinary Transforming Growth Factor Beta 1(TGF-B1) and Monocyte Chemotactic Protein (MCP-1) before and after valve ablation and its prognostic value in Posterior urethral valve.

Material and Method:

This prospective study was conducted from September 2016 to August 2018. The study group included 20 consecutive male babies with the diagnosis of PUV treated and followed up versus equal numbers of age matched control without any renal or urinary tract disease. Pre-operative urine samples were collected in Operative room. Cystoscopy and valve ablation was done. Follow up was done clinically by urinary stream and radiologically with VCUG. Follow-up was planned at 1 month, 3 months and 6 months following cystoscopic valve ablation. All collected urine samples were centrifuged at 10,000 rpm for 20 minutes. Supernatant was collected and two divided aliquots were stored at -200c to be thawed on the day of assay. Optical density of each well was recorded at 450 nm and 540 nm A p-value of <0.05 was considered to be statistically significant.

Result and Discussion:

Out of 20 cases of PUV, 14 (70%) cases were 1st born males of their family. The median age at the time of valve ablation in PUV cases was 2.5 (1.20-3.87) years.. Most common symptoms are fever and UTI. The preoperative median serum creatinine level was 1.65 mg/dl(1.22-2.42) pre-ablation, and fall significantly after ablation. Median eGFR level (calculated) was 25.635 (16.38-35.40) and after 6 months was 71.490 (45.44-96.93). Preoperative median MCP1 in PUV cases was 147.2 (82.8-512.5) and significant difference was also found in 1st, 3rd and 6th months after surgery (p<0.001, p=0.004 and p=0.002).Preoperative median TGF-B1 level was 197.8 pg/ml (79.9-386.4). There was no statistically significant change in TGF-B1 level at preoperative to 1 month and preop to 3 months after surgery but at 6 months after surgery the median TGF-B1 level significantly decreased as compared with preoperative TGF-B1 level.

Conclusion:

TGF β1 and MCP1 can be considered as prognostic urinary biomarkers in patients of PUV and can be used to specify and counsel patient's attendant regarding possibility of ESRD and need for further intervention.

Macrophage TGF-β1 and the Proapoptotic Extracellular Matrix Protein BIGH3 Induce Renal Cell Apoptosis in Prediabetic and Diabetic Conditions

Metabolically stressed kidney is in part characterized by infiltrating macrophages and macrophage-derived TGF-β1 that promote the synthesis of various ECM molecules. TGF-β1 strongly enhances the expression of the gene TGFBI that encodes a cell-adhesion class, proapoptotic ECM protein called BIGH3. We hypothesized that in a diabetic environment a relationship between infiltrating macrophages, macrophage-derived TGF-β1, and BIGH3 protein promotes renal cell death. To investigate this hypothesis, we used our mouse model of diabetic complications. Mice on a high-fat diet developed hypercholesterolemia, and exposure to streptozotocin rendered hypercholesterolemic mice diabetic. Immunohistochemical images show increased macrophage infiltration and BIGH3 protein in the kidney cortices of hypercholesterolemic and diabetic mice. Macrophages induced a two-fold increase in BIGH3 expression and an 86% increase in renal proximal tubule epithelial cell apoptosis. TGF-β1 antibody and TGF-β1 receptor chemical antagonist blocked macrophage-induced apoptosis. BIGH3 antibody completely blocked apoptosis that was induced by TGF-β1, and blocked apoptosis induced by exogenous recombinant BIGH3. These results uncover a distinctive interplay of macrophage-derived TGF-β1, BIGH3 protein, and apoptosis, and indicate that BIGH3 is central in a novel pathway that promotes diabetic nephropathy. Macrophage TGF-β1 and BIGH3 are identified as prediabetic biomarkers, and potential therapeutic targets for intervention in prediabetic and diabetic individuals.

TGF-β Signaling in Gastrointestinal Cancers: Progress in Basic and Clinical Research

Transforming growth factor (TGF)-β superfamily proteins have many important biological functions, including regulation of tissue differentiation, cell proliferation, and migration in both normal and cancer cells. Many studies have reported that TGF-β signaling is associated with disease progression and therapeutic resistance in several cancers. Similarly, TGF-β-induced protein (TGFBI)—a downstream component of the TGF-β signaling pathway—has been shown to promote and/or inhibit cancer. Here, we review the state of basic and clinical research on the roles of TGF-β and TGFBI in gastrointestinal cancers.

Urinary biomarkers for early diabetic nephropathy: beyond albuminuria

Diabetic nephropathy (DN) is the most common cause of end-stage kidney disease in the USA and accounts for a significant increase in morbidity and mortality in patients with diabetes. Early detection is critical in improving clinical management. Although microalbuminuria is regarded as the gold standard for diagnosing the onset of DN, its predictive powers are limited. Consequently, great efforts have been made in recent years to identify better strategies for the detection of early stages of DN and progressive kidney function decline in diabetic patients. Here, we review the various urinary biomarkers that have emerged from these studies which hold promise as more sensitive diagnostic tools for the earlier detection of diabetic kidney disease and the prediction of progression to end-stage kidney disease. A number of key biomarkers present in the urine have been identified that reflect kidney injury at specific sites along the nephron, including glomerular/podocyte damage and tubular damage, oxidative stress, inflammation and activation of the intrarenal renin-angiotensin system. We also describe newer approaches, including urinary microRNAs, which are short noncoding mRNAs that regulate gene expression, and urine proteomics, that can be used to identify potential novel biomarkers in the development and progression of diabetic kidney disease.

Inhibiting Amadori-modified albumin formation improves biomarkers of podocyte damage in diabetic rats

Recent studies have shown that urinary excretion of podocyte proteins is an indicator of podocyte injury, and that podocyte abnormalities and elevated concentrations of Amadori-modified glycated albumin (AGA) are linked to the development of diabetic nephropathy and to each other. We evaluated relationships between urinary markers of podocyte damage, increased AGA and filtration function in rats made diabetic by streptozotocin injection and treated for 8 weeks with a compound that inhibits the formation of AGA, with age-matched nondiabetic and diabetic rats serving as controls. Blood and urine were collected for measurement of glycated albumin, creatinine, albumin, nephrin, podocalyxin, and βig-h3 protein. The elevated circulating concentrations of glycated albumin and higher urinary levels of these podocyte markers as well as of albumin that were observed in diabetic rats compared with nondiabetic controls were significantly reduced in animals receiving test compound, and decrease in urinary biomarkers correlated with reduction in AGA. The results provide evidence that lowering the concentration of AGA, independent of filtration status and hyperglycemia, reduces urinary nephrin, podocalyxin, and βig-h3 protein, linking the increased glycated albumin associated with diabetes to podocyte abnormalities and shedding of podocyte proteins into the urine.

Transforming growth Factor-Beta-Induced Protein (TGFBI)/(βig-H3): a matrix protein with dual functions in ovarian cancer

Transforming growth factor-beta-induced protein (TGFBI, also known as βig-H3 and keratoepithelin) is an extracellular matrix protein that plays a role in a wide range of physiological and pathological conditions including diabetes, corneal dystrophy and tumorigenesis. Many reports indicate that βig-H3 functions as a tumor suppressor. Loss of βig-H3 expression has been described in several cancers including ovarian cancer and promoter hypermethylation has been identified as an important mechanism for the silencing of the TGFBI gene. Our recent findings that βig-H3 is down-regulated in ovarian cancer and that high concentrations of βig-H3 can induce ovarian cancer cell death support a tumor suppressor role. However, there is also convincing data in the literature reporting a tumor-promoting role for βig-H3. We have shown βig-H3 to be abundantly expressed by peritoneal cells and increase the metastatic potential of ovarian cancer cells by promoting cell motility, invasion, and adhesion to peritoneal cells. Our findings suggest that βig-H3 has dual functions and can act both as a tumor suppressor or tumor promoter depending on the tumor microenvironment. This article reviews the current understanding of βig-H3 function in cancer cells with particular focus on ovarian cancer.

Early alteration of urinary exosomal aquaporin 1 and transforming growth factor β1 after release of unilateral pelviureteral junction obstruction

BACKGROUND/PURPOSE

Down-regulation of aquaporin 1 (AQP1) and up-regulation of transforming growth factor β(1) (TGF-β(1)) in the renal parenchyma have been demonstrated in children who underwent pyeloplasty for pelviureteral junction obstruction. However, no information about urinary exosomal AQP1 and TGF-β(1) during postobstructive polyuria in children with congenital unilateral hydronephrosis is available. The aim of the present study is to evaluate the urine concentration of exosomal AQP1 and TGF-β(1) on the first and the second day after surgery in children who underwent pyeloplasty.

METHODS

Twenty-two patients (age, 36.2 ± 17.1 months) with unilateral pelviureteral junction obstruction were examined in the study. For the first 2 days after the operation, the urine was collected separately from pyelostomy draining only from the postobstructed kidney and from the bladder catheter draining mostly from the contralateral kidney, which was used as an internal control. Urinary output, urinary osmolality, sodium, β(2)-microglobulin (β(2)-MG), and creatinine, as well as urinary exosomal AQP1 and TGF-β(1) excretion, were tested in each sample.

RESULTS

After pyeloplasty, a significantly decreased urinary excretion of exosomal AQP1 (≈ 64%) was found in the postobstructed kidney. The patients developed polyuria (807 ± 216 mL/24 h vs 484 ± 144 mL/24 h at day 1, 1021 ± 348 mL/24 h vs 603 ± 228 mL/24 h at day 2; P < .01) and reduced urine osmolality (115 ± 44 mOsm/kg vs 282 ± 61 mOsm/kg at day 1, 139 ± 39 vs 303 ± 46 mOsm/kg at day 2; P < .01) that persisted for 48 hours. In parallel, urinary TGF-β(1) and β(2)-MG (normalized for creatinine) from the postobstructed kidney were significantly higher compared with the contralateral kidney. The urine output and urinary sodium concentration from the postobstructed kidney elevated significantly on the second day after the release of obstruction compared with those on the first day. The contralateral kidney also showed same trends.

CONCLUSIONS

The down-regulation of urinary exosomal AQP1 in the postobstructed kidney may account for the polyuria, hypotonic urine, and elevated urinary β(2)-MG. The urinary TGF-β(1) level locally increased in the postobstructed kidney may be involved in renal AQP1 down-regulation.

Increased urinary excretion of nephrin, podocalyxin, and βig-h3 in women with preeclampsia

Emerging evidence has shown that podocyte injury and reduced specific podocyte protein expressions contribute to proteinuria in preeclampsia. We collected urine specimens from women with preeclampsia to study whether podocyte-specific protein shedding is associated with renal barrier dysfunction. Urine specimens from women with normal pregnancies and from pregnant women complicated by chronic hypertension were used for comparison. We determined soluble podocyte slit protein nephrin levels in the urine specimens. Podocalyxin, βig-h3, and VEGF concentrations were also measured. We found that nephrin and podocalyxin were barely detectable in the urine specimens from normal pregnant women and from women with chronic hypertension. In preeclampsia, urinary nephrin and podocalyxin concentrations were significantly increased and highly correlated to each other, r(2) = 0.595. Nephrin and podocalyxin were also correlated with urine protein concentrations. βig-h3 was detected in the urine specimens from women with preeclampsia, and it is highly correlated with nephrin and podocalyxin concentrations in preeclampsia. βig-h3 was undetectable in normal pregnancy and pregnancy complicated by chronic hypertension. Elevated VEGF levels were also found in women with preeclampsia compared with those of normal pregnancy and pregnancy complicated by chronic hypertension. These results provide strong evidence that podocyte protein shedding occurs in preeclampsia, and their levels are associated with proteinuria. The finding of urinary βig-h3 excretion in preeclampsia suggests that increased transforming growth factor activity might also be involved in the kidney lesion in this pregnancy disorder.

Role of urinary biomarkers in the diagnosis of congenital upper urinary tract obstruction

Background:

Congenital obstructive uropathy constitutes a significant cause of morbidity in children. Currently, there is no reference standard for the diagnosis of renal obstruction in children. The noninvasive measurement of biomarkers in voided urine has considerable appeal as a potential application in children with congenital obstructive nephropathy. The aim of the present review is to explore the current role of biomarkers in the diagnosis and follow-up of obstructive uropathy in children.

Materials and Methods:

The literature database (PubMed) was searched from inception to May 2007 regarding the role of urinary biomarkers in the diagnosis and follow-up of children with congenital obstructive uropathy.

Results:

The review included 23 experimental and 33 prospective controlled clinical studies. Several cytokines, peptides, enzymes and microproteins were identified as major contributors to or ensuing from obstruction-induced renal fibrosis and apoptosis. The most important biomarkers were transforming growth factor-β₁ (TGFβ₁), epidermal growth factor (EGF), endothelin-1 (ET-1), urinary tubular enzymes [N-acetyl-β-D-glucosaminidase (NAG), γ-glutamyl transferase (GGT) and alkaline phosphatase (ALP)], and microproteins [β₂-microglobulin (β₂M), microalbumin (M. Alb) and micrototal protein (M.TP)]. All biomarkers showed different degrees of success but the most promising markers were TGFβ₁, ET-1 and a panel of tubular enzymes. These biomarkers showed sensitivity of 74.3% to 100%, specificity of 80% to 90% and overall accuracy of 81.5% to 94% in the diagnosis of congenital obstructive uropathy in children. Moreover, some of the markers were valuable in differentiation between dilated non-obstructed kidneys in need of conservative management and obstructed kidneys in need of surgical correction. Some studies demonstrated that urinary biomarkers are helpful in the evaluation of success of treatment of children with congenital renal obstruction. Some limitations of the previous studies include lack of different types of controls and small sample size. Larger studies with variable controls are invited to confirm the clinical usefulness of biomarkers in the diagnosis and follow-up of children with congenital obstructive uropathy.

Conclusion:

Urinary biomarkers are a promising tool that could be used as a noninvasive assessment of congenital renal obstruction in children.

Urinary biomarkers in prenatally diagnosed unilateral hydronephrosis

The introduction of prenatal ultrasonography as a screening method entails an increasing number of infants diagnosed with prenatal hydronephrosis. Ureteropelvic junction obstruction accounts for 35% of prenatal hydronephrotic cases. Urinary tract obstruction that occurs during early kidney development affects renal morphogenesis, maturation and growth, and in the most severe cases this will ultimately cause renal insufficiency. A major challenge in the clinical management of these patients is to preserve renal function by selection of the 15%-20% who require early surgical intervention, leaving those for whom watchful waiting may be appropriate because of spontaneous resolution/stabilization without significant loss of renal function. Today, this requires medical surveillance, including repetitive invasive diuretic renograms relying on arbitrary threshold values, and therefore there is a need for non-arbitrary, non-invasive urinary biomarkers that may be used as predictors for renal structural changes and/or decreasing renal function, and thereby provide the surgeon with more clear indications for surgical intervention. In this review, we summarize the currently well-known facts about urinary biomarkers in ureteropelvic junction obstruction concerning renal function, and we also suggest potential novel urinary biomarkers.

Review: Serum and urine biomarkers of kidney disease: A pathophysiological perspective

The use of reliable biomarkers is becoming increasingly important for the improved management of patients with acute and chronic kidney diseases. Recent developments have identified a number of novel biomarkers in serum or urine that can determine the potential risk of kidney damage, distinguish different types of renal injury, predict the progression of disease and have the potential to assess the efficacy of therapeutic intervention. Some of these biomarkers can be used independently while others are more beneficial when used in combination with knowledge of other clinical risk factors. Advances in gene expression analysis, chromatography, mass spectrometry and the development of sensitive enzyme-linked immunosorbent assays have facilitated accurate quantification of many biomarkers. This review primarily focuses on describing new and established biomarkers, which identify and measure the various pathophysiological processes that promote kidney disease. It provides an overview of some of the different classes of renal biomarkers that can be assessed in serum/plasma and urine, including markers of renal function, oxidative stress, structural and cellular injury, immune responses and fibrosis. However, it does not explore the current status of these biomarkers in terms of their clinical validation.

Serum and Urinary Biomarkers Determination and Their Significance in Diagnosis of Kidney Diseases

Chronic kidney disease (CKD) is becoming a major public health problem worldwide due to the epidemic increase of patients on renal replacement therapy and their high cardiovascular morbidity and mortality. The only effective approach to this problem is prevention and early detection of CKD. In addition, despite significant improvements in therapeutics, the mortality and morbidity associated with acute kidney injury (AKI) remain high. A major reason for this is the lack of early markers for AKI, and hence an unacceptable delay in initiating therapy. Therefore, there is a pressing need to develop biomarkers (proteins and other molecules in the blood or urine) for renal disease, which might assist in diagnosis and prognosis and might provide endpoints for clinical trials of drugs designed to slow the progression of renal insufficiency. Besides serum creatinine, promising novel biomarkers for AKI include a plasma panel (neutrophil gelatinase-associated lipocalin-NGAL and cystatin C) and a urine panel (NGAL, kidney injury molecule-1, interleukin-18, cystatin C, alpha 1-microglobulin, Fetuin-A, Gro-alpha, and meprin). For CKD, these include a similar plasma panel and a urine panel (NGAL, asymmetric dimethylarginine, and liver-type fatty acid-binding protein). Increased plasma and urinary TGF-β1 levels might contribute to the development of chronic tubulointerstitial disease, indicating the possible therapeutic implications. Furthermore, to differentiate lower urinary tract infection and pyelonephritis interleukin-6 and serum procalcitonin levels were introduced. It will be important in future studies to validate the sensitivity and specificity of these biomarker panels in clinical samples from large cohorts and in multiple clinical situations.

Aldose reductase inhibitor ameliorates renal vascular endothelial growth factor expression in streptozotocin-induced diabetic rats

PURPOSE

The vascular endothelial growth factor (VEGF) expression of podocyte is one of the well-known major factors in development of diabetic nephropathy. In this study, we investigated the effects of aldose reductase inhibitor, fidarestat on diabetic nephropathy, and renal VEGF expression in a type 1 diabetic rat model.

MATERIALS AND METHODS

Twenty four Sprague-Dawley male rats which were performed intraperitoneal injection of streptozotocin and normal six rats were divided into four groups including a normal control group, untreated diabetic control group, aldose reductase (AR) inhibitor (fidarestat, 16 mg kg(-1) day(-1)) treated diabetic group, and angiotensin receptor blocker (losartan, 20 mg kg(-1) day(-1)) treated diabetic group. We checked body weights and blood glucose levels monthly and measured urine albumin-creatinine ratio (ACR) at 8 and 32 weeks. We extracted the kidney to examine the renal morphology and VEGF expressions.

RESULTS

The ACR decreased in fidarestat and losartan treated diabetic rat groups than in untreated diabetic group (24.79 +/- 11.12, 16.11 +/- 9.95, and 84.85 +/- 91.19, p < 0.05). The renal VEGF messenger RNA (mRNA) and protein expression were significantly decreased in the fidarestat and losartan treated diabetic rat groups than in the diabetic control group.

CONCLUSION

We suggested that aldose reductase inhibitor may have preventive effect on diabetic nephropathy by reducing renal VEGF overexpression.

Urinary biomarkers involved in type 2 diabetes: a review

Diabetes mellitus is one of the most challenging health concerns of the 21st century. With at least 30% of the diabetic population remaining undiagnosed, effective and early diagnosis is of critical concern. Development of a diagnostic test, more convenient and reliable than those currently used, would therefore be highly beneficial. Urine as a diagnostic medium allows for non-invasive detection of biomarkers, including some associated with type 2 diabetes and its complications. This review provides a synopsis of those urinary biomarkers that potentially may provide a basis for the development of improved diagnostic tests. Three main pathways for the sourcing of potential makers are identified: kidney damage, oxidative stress and low-grade inflammation including atherosclerosis/vascular damage. This review briefly presents each pathway and some of the most relevant urinary biomarkers that may be used to monitor the development or progression of diabetes and its complications. In particular, biomarkers of renal dysfunction such as transferrin, type IV collagen and N-acetyl-beta-D-glucosaminidase might prove to be more sensitive than urinary albumin, the current gold standard, in the detection of incipient nephropathy and risk assessment of cardiovascular disease. Inflammatory markers including orosomucoid, tumour necrosis factor-alpha, transforming growth factor-beta, vascular endothelial growth factor and monocyte chemoattractant protein-1, as well as oxidative stress markers such as 8-hydroxy-2'deoxyguanosine may also be useful biomarkers for diagnosis or monitoring of diabetic complications, particularly kidney disease. However, the sensitivity of these markers compared with albumin requires further investigation.

Aldosterone and diabetic kidney disease

Aldosterone plays an important role in salt and water homeostasis and blood pressure control through the classical mineralocorticoid receptor. However, recent findings of the mineralocorticoid receptor in nonepithelial tissues suggest that aldosterone may have additional functions. Significant evidence now exists suggesting that aldosterone directly induces tissue injury. Systemic or local aldosterone has emerged as a multifunctional hormone exhibiting profibrotic and proinflammatory actions that extend beyond the classical hemodynamic effect. The incomplete blockade of the renin-angiotensin-aldosterone system by angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers has led to experimental and clinical efforts using aldosterone inhibition. Recently, these efforts have provided us with an expanded understanding of a new pathogenic role for aldosterone in diabetic vascular complications. This article focuses on the role of aldosterone in the pathogenesis of diabetic kidney disease and recent important clinical data supporting the inhibition of aldosterone in treating diabetic kidney disease.

C-terminal fragment of transforming growth factor beta-induced protein (TGFBIp) is required for apoptosis in human osteosarcoma cells

Transforming growth factor beta-induced protein (TGFBIp), is secreted into the extracellular space. When fragmentation of C-terminal portions is blocked, apoptosis is low, even when the protein is overexpressed. If fragmentation occurs, apoptosis is observed. Whether full-length TGFBIp or integrin-binding fragments released from its C-terminus is necessary for apoptosis remains equivocal. More importantly, the exact portion of the C-terminus that conveys the pro-apoptotic property of TGFBIp is uncertain. It is reportedly within the final 166 amino acids. We sought to determine if this property is dependent upon the final 69 amino acids containing the integrin-binding, EPDIM and RGD, sequences. With MG-63 osteosarcoma cells, transforming growth factor (TGF)-beta1 treatment increased expression of TGFBIp over 72 h (p<0.001). At this time point, apoptosis was significantly increased (p<0.001) and was prevented by an anti-TGFBIp, polyclonal antibody (p<0.05). Overexpression of TGFBIp by transient transfection produced a 2-fold increase in apoptosis (p<0.01). Exogenous purified TGFBIp at concentrations of 37-150 nM produced a dose dependent increase in apoptosis (p<0.001). Mass spectrometry analysis of TGFBIp isolated from conditioned medium of cells treated with TGF-beta1 revealed truncated forms of TGFBIp that lacked integrin-binding sequences in the C-terminus. Recombinant TGFBIp truncated, similarly, at amino acid 614 failed to induce apoptosis. A recombinant fragment encoding the final 69 amino acids of the TGFBIp C-terminus produced significant apoptosis. This apoptosis level was comparable to that induced by TGF-beta1 upregulation of endogenous TGFBIp. Mutation of the integrin-binding sequence EPDIM, but not RGD, blocked apoptosis (p<0.001). These pro-apoptotic actions are dependent on the C-terminus most likely to interact with integrins.

The extracellular matrix protein TGFBI promotes myofibril bundling and muscle fibre growth in the zebrafish embryo

The extracellular matrix protein Tgfbi has been shown to localise to myotendinous junctions in mouse and postulated to interact with the transmembrane protein Integrin alpha7beta1, which, in parallel with the Dystrophin-associated protein complex, is critical for linkage between the extracellular matrix and the cytoskeleton of muscle fibres. Here we use a GFP-tagged form of Tgfbi to analyse its distribution in the developing skeletal muscle of the zebrafish embryos and antisense morpholino oligonucleotides to investigate the function of the endogenous protein. We find that although tagged Tgfbi accumulates at the myosepta, the attachment of muscle fibres to the myosepta is established and maintained normally in morphant embryos; however, the fibres show a marked reduction in their growth and a disruption of their myofibril bundles.

Lack of association between TGF-beta-1 genotypes and microalbuminuria in essential hypertensive men

BACKGROUND

Polymorphisms within the gene for transforming growth factor (TGF)-beta-1, a pro-fibrogenic cytokine pathophysiologically involved in hypertension and hypertensive target damage, might modulate the biological activity of the encoded protein. Through that mechanism, they might contribute to microalbuminuria, a marker of subclinical renal damage and a correlate of systemic inflammation and endothelial dysfunction in hypertension, a possibility never before tested. For this reason, we assessed the association of four TGF-beta-1 polymorphic variants (C-509T, Leu(10)-->Pro, Arg(25)-->Pro, Thr(263)-->Ile) with albuminuria in uncomplicated essential hypertensive men, using (circulating active + acid-activatable latent) TGF-beta-1 levels as an indirect index of their in vivo biological activity. Because of the close pathophysiological link of TGF-beta-1 with the renin-angiotensin system, we also tested the behaviour of the angiotensin converting enzyme (ACE) deletion/insertion (D/I) polymorphism.

METHODS

Albuminuria (three overnight collections), office and 24-h BP, left ventricular mass index (LVMI), BMI, renal function, glucose, lipids, plasma TGF-beta-1 (n = 162, ELISA) were measured in 222 genetically unrelated, never-treated, uncomplicated Caucasian hypertensive men. ACE D/I polymorphisms were analysed by the polymerase chain reaction technique or a 5' nuclease assay with further restriction analysis when required.

RESULTS

Urine albumin levels or microalbuminuria (albuminuria > or =15 microg/min) did not differ by TGF-beta-1 genotypes, but both parameters were more frequent in ACE D/D homozygotes. Plasma TGF-beta-1 was similar across genetic backgrounds and was unrelated to albuminuria. Cardiovascular, renal, metabolic parameters were homogeneously distributed across genotypes.

CONCLUSIONS

In contrast to its link with the ACE D/I genotype, microalbuminuria was independent of TGF-beta-1 polymorphism in this group of never-treated, uncomplicated essential hypertensive men.

Effect of eplerenone, enalapril and their combination treatment on diabetic nephropathy in type II diabetic rats

BACKGROUND

Recent data suggest that aldosterone antagonists have beneficial effects on diabetic nephropathy. In this study, we investigated the dose-dependent effect of eplerenone and a combined treatment with eplerenone and enalapril compared with each drug alone on renal function in type II diabetic rats. To further explore the molecular mechanism of action of combination therapy, we also performed in vitro study.

METHODS

The animals were divided into six groups as follows: normal control Long-Evans Tokushima Otsuka (LETO) rats, Otsuka Long-Evans Tokushima Fatty (OLETF) rats, OLETF rats treated with low dose of eplerenone (50 mg/kg/day), OLETF rats treated with high dose of eplerenone (200 mg/kg/day), OLETF rats treated with enalapril (10 mg/kg/day) and OLETF rats treated with a combination of both drugs (eplerenone 200 mg/kg/day and enalapril 10 mg/kg/day) for 6 months.

RESULTS

Treatment of OLETF rats had no significant effect on body weight, kidney weight and blood glucose levels. However, urinary albumin excretion, glomerular filtration rate and glomerulosclerosis were significantly improved in the enalapril group and improvement was observed in a dose-dependent manner in the eplerenone groups; the most dramatic decreases were observed in the combination group. In accordance with these findings, renal expressions of TGF-beta1, type IV collagen and PAI-1 were also markedly decreased in the treatment groups, with the combined treatment providing the most significant level of improvement. In cultured mesangial cells, combined treatment resulted in an additive decrease in TGF-beta1, PAI-1 and collagen gene expressions and protein production induced by high glucose and aldosterone stimulation.

CONCLUSIONS

Aldosterone receptor antagonism provided additional benefits beyond blockade of the renin-angiotensin system in type II diabetic nephropathy.

Pioglitazone attenuates diabetic nephropathy through an anti-inflammatory mechanism in type 2 diabetic rats

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) are nuclear transcription factors that play a role in insulin sensitivity, lipid metabolism and inflammation. However, the effects of PPARgamma agonist on renal inflammation have not been fully examined in type 2 diabetic nephropathy.

METHODS

In the present study, we investigated the effect and molecular mechanism of the PPARgamma agonist, pioglitazone, on the progression of diabetic nephropathy in type 2 diabetic rats. Inflammatory markers including NF-kappaB, MCP-1 and pro-fibrotic cytokines were determined by RT-PCR, western blot, immunohistochemical staining and EMSA. In addition, to evaluate the direct anti-inflammatory effect of PPARgamma agonist, we performed an in vitro study using mesangial cells.

RESULTS

Treatment of OLETF rats with pioglitazone improved insulin sensitivity and kidney/body weight, but had a little effect on blood pressure. Pioglitazone treatment markedly reduced urinary albumin and MCP-1 excretion, and ameliorated glomerulosclerosis. In cDNA microarray analysis using renal cortical tissues, several inflammatory and profibrotic genes were significantly down-regulated by pioglitazone including NF-kappaB, CCL2, TGFbeta1, PAI-1 and VEGF. In renal tissues, pioglitazone treatment significantly reduced macrophage infiltration and NF-kappaB activation in association with a decrease in type IV collagen, PAI-1, and TGFbeta1 expression. In cultured mesangial cells, pioglitazone-activated endogenous PPARgamma transcriptional activity and abolished high glucose-induced collagen production. In addition, pioglitazone treatment also markedly suppressed high glucose-induced MCP-1 synthesis and NF-kappaB activation.

CONCLUSIONS

These data suggest that pioglitazone not only improves insulin resistance, glycaemic control and lipid profile, but also ameliorates renal injury through an anti-inflammatory mechanism in type 2 diabetic rats.

Therapeutic potential of TGF-beta inhibition in chronic renal failure

Chronic kidney diseases are emerging as a worldwide public health problem. The progression of kidney diseases closely correlates with the accumulation of extracellular matrix leading to glomerulosclerosis and tubulointerstitial injury. Transforming growth factor (TGF)-beta has been identified as a key mediator of kidney matrix accumulation. Overexpression of TGF-beta isoforms and their receptors was observed in a variety of renal diseases in both animals and humans. Given its crucial role in fibrotic kidney disease, TGF-beta has been recently considered as a possible target in the management of chronic renal diseases. This review discusses the role of TGF-beta in renal fibrosis and provides an overview of the strategies that, when interfering with TGF-beta expression and signalling, could be employed as new renoprotective treatments.

Pelvi-ureteric junction obstruction in children: the role of urinary transforming growth factor-?1and epidermal growth factor

OBJECTIVES

To investigate the role of transforming growth factor beta(1) (TGF-beta(1)) and epidermal growth factor (EGF) in voided urine for the diagnosis and follow-up of children with pelvi-ureteric junction obstruction (PUJO).

PATIENTS, SUBJECTS AND METHODS

The study included 35 children with unilateral PUJO who had a pyeloplasty, and 30 healthy control children. Urine samples were obtained from the bladders of patients before surgery, and as voided samples at 1, 2, 3, 6, 9 and 12 months after surgery. Bladder urine samples were also collected from all 30 children in the control group. TGF-beta(1) and EGF were then measured in all the urine samples.

RESULTS

The level of bladder TGF-beta(1) before surgery in the patients was significantly higher than that in the healthy control group. A threshold of 190 pg/mg creatinine gave a sensitivity of 100%, a specificity of 80%, a positive predictive value of 85.4%, negative predictive value of 100% and an overall accuracy of 90.8%. Compared with the value before surgery, urinary TGF-beta(1) was significantly lower at 1 year after pyeloplasty. There was no significant difference between the level of EGF before surgery in the patients and that in the control group, and no significant difference in the level of EGF before and after surgery over the follow-up.

CONCLUSION

We do not recommend using EGF levels in voided urine in the routine diagnosis of children with hydronephrosis. The urinary level of TGF-beta(1) is a useful noninvasive tool for the long-term follow-up of children with PUJO treated by pyeloplasty. Further studies with various controls are required to confirm the diagnostic accuracy of TGF-beta(1) in children with PUJO.

Accurate measurement and clinical significance of urinary transforming growth factor-beta1

Transforming growth factorbeta1 (TGF-beta1) is the main modulator of the healing process after tissue injury. In the kidney, if TGF-beta1 release is not switched off, extracellular matrix components (ECM) are accumulated and tissue fibrosis occurs. Urinary TGF-beta1 levels reflect its renal production and it has been determined in various types of glomerular disease. In this review, a critical analysis of the different immunoassays that have been used for the measurement of TGF-beta1 in the urine is presented and the importance of the serial determination of urinary TGF-beta1 levels in patients with various types of renal disease is discussed.