Transforming growth factor-beta(1) and myofibroblasts: a potential pathway towards renal scarring in human glomerular disease

miR-29c Inhibits Renal Interstitial Fibrotic Proliferative Properties through PI3K-AKT Pathway

Renal fibrosis, in particular tubulointerstitial fibrosis, which is characterized by an increased extracellular matrix (ECM) formation and development in the interstitium, is the common end pathway for nearly all progressive kidney disorders. One of the sources for this matrix is the epithelial to mesenchymal transition (EMT) from the tabular epithelium. The driving force behind it is some profibrotic growth factors such as transforming growth factor-β (TGF-β) which is responsible for the formation of collagen in renal fibrosis. miR-29c, which is an antifibrotic microRNA, downregulates renal interstitial fibrosis by downregulating the TGF-β and collagen. However, it is not known whether miR-29c mediates the TGF-β1-driven PI3K-Akt pathway and Col-1 triggering within NRK-52E cultures. The main objective of this investigation was to examine the influence of miR-29c on the downregulation of the TGF-β1-driven PI3K-Akt pathway and Col-1 triggering in NRK-52E cultures. This study revealed that miR-29c inhibited TGF-β1 expression in NRK-52E cell cultures. Overexpression of miR-29c significantly inhibits NRK-52E culture proliferation mediated by TGF-β1. miR-29c inhibited the expression of Col-1 and decreased PI3K/Akt phosphorylation. These findings revealed a novel mechanism by which miR29c inhibits the proliferation of renal interstitial fibrotic cultures by downregulating the PI3k-Akt pathway, which is controlled by TGF-β1.

The Usefulness of Urinary Periostin, Cytokeratin-18, and Endoglin for Diagnosing Renal Fibrosis in Children with Congenital Obstructive Nephropathy

Congenital obstructive nephropathy (CON) leads to renal fibrosis and chronic kidney disease. The aim of the study was to investigate the predictive value of urinary endoglin, periostin, cytokeratin-18, and transforming growth factor-β1 (TGF-β1) for assessing the severity of renal fibrosis in 81 children with CON and 60 controls. Children were divided into three subgroups: severe, moderate scars, and borderline lesions based on 99mTc-ethylenedicysteine scintigraphy results. Periostin, periostin/Cr, and cytokeratin-18 levels were significantly higher in the study group compared to the controls. Children with severe scars had significantly higher urinary periostin/Cr levels than those with borderline lesions. In multivariate analysis, only periostin and cytokeratin-18 were independently related to the presence of severe and moderate scars, and periostin was independently related to borderline lesions. However, periostin did not differentiate advanced scars from borderline lesions. In ROC analysis, periostin and periostin/Cr demonstrated better diagnostic profiles for detection of advanced scars than TGF-β1 and cytokeratin-18 (AUC 0.849; 0.810 vs. 0.630; 0.611, respectively) and periostin for detecting borderline lesions than endoglin and periostin/Cr (AUC 0.777 vs. 0.661; 0.658, respectively). In conclusion, periostin seems to be a promising, non-invasive marker for assessing renal fibrosis in children with CON. CK-18 and TGF-β1 demonstrated low utility, and endoglin was not useful for diagnosing advanced scars.

Biomarkers in Fabry Disease. Implications for Clinical Diagnosis and Follow-up

Fabry disease (FD) is a lysosomal storage disorder caused by deficient alpha-galactosidase A activity in the lysosome due to mutations in the GLA gene, resulting in gradual accumulation of globotriaosylceramide and other derivatives in different tissues. Substrate accumulation promotes different pathogenic mechanisms in which several mediators could be implicated, inducing multiorgan lesions, mainly in the kidney, heart and nervous system, resulting in clinical manifestations of the disease. Enzyme replacement therapy was shown to delay disease progression, mainly if initiated early. However, a diagnosis in the early stages represents a clinical challenge, especially in patients with a non-classic phenotype, which prompts the search for biomarkers that help detect and predict the evolution of the disease. We have reviewed the mediators involved in different pathogenic mechanisms that were studied as potential biomarkers and can be easily incorporated into clinical practice. Some accumulation biomarkers seem to be useful to detect non-classic forms of the disease and could even improve diagnosis of female patients. The combination of such biomarkers with some response biomarkers, may be useful for early detection of organ injury. The incorporation of some biomarkers into clinical practice may increase the capacity of detection compared to that currently obtained with the established diagnostic markers and provide more information on the progression and prognosis of the disease.

Candidate rejuvenating factor GDF11 and tissue fibrosis: friend or foe?

Growth differentiation factor 11 (GDF11 or bone morphogenetic protein 11, BMP11) belongs to the transforming growth factor-β superfamily and is closely related to other family member-myostatin (also known as GDF8). GDF11 was firstly identified in 2004 due to its ability to rejuvenate the function of multiple organs in old mice. However, in the past few years, the heralded rejuvenating effects of GDF11 have been seriously questioned by many studies that do not support the idea that restoring levels of GDF11 in aging improves overall organ structure and function. Moreover, with increasing controversies, several other studies described the involvement of GDF11 in fibrotic processes in various organ setups. This review paper focuses on the GDF11 and its pro- or anti-fibrotic actions in major organs and tissues, with the goal to summarize our knowledge on its emerging role in regulating the progression of fibrosis in different pathological conditions, and to guide upcoming research efforts.

Biomarkers in Progressive Chronic Kidney Disease. Still a Long Way to Go

The traditional chronic kidney disease (CKD) biomarkers (eGFR based on serum creatinine, sex and age and albuminuria) cannot predict a patient's individual risk for developing progressive CKD. For this reason, it is necessary to identify novel CKD biomarkers that will be able to predict which patients are prone to develop progressive disease and discriminate between disease processes in different parts of the nephron (glomeruli or tubules). A good biomarker should change before or simultaneously with lesion development and its changes should correlate strongly with lesion development. Also, there should be a close relationship between severity of injury and amount of detectable biomarker and its levels should decrease with diminishing injury. Among the large number of molecules under investigation, we have reviewed the most promising ones: NGAL and KIM-1, MCP-1, MMP-9, clusterin, MMP-9, TIMP-1, Procollagen I alpha 1 and suPAR. All these, have been studied as biomarkers for prediction of CKD progression in cohorts of patients with chronic kidney disease of different stages and various aetiologies (proteinuric and non-proteinuric, glomerulonephritides, diabetic, hypertensive and polycystic kidney disease). There is evidence that these molecules could be useful as biomarkers for progressive chronic kidney disease, however, the available data are not enough to draw final conclusions. Further studies with large cohorts and long follow-up are required to identify appropriate biomarkers, that will be able to accurately and reliably define the risk for progressive chronic kidney disease.

Niao Du Kang Mixture Increases the Expression of mir-129-5p to Relieve Renal Fibrosis

Objective

To investigate the efficacy of Niao Du Kang (NDK) mixture in renal fibrosis of rats and to explore the mechanism underlying the effect of NDK on renal fibrosis.

Methods

Unilateral ureteral obstruction (UUO) was used to replicate a rat renal interstitial fibrosis model. The drug-administered groups were given 20 ml/kg (NDK-H), 10 ml/kg (NDK-M), and 5 ml/kg (NDK-L) NDK mixture once a day for 21 days beginning 48 hours after surgery. The 24-hour urine protein and serum creatinine (CR) levels in the sham group rats, UUO rats, and NDK mixture-treated rats were measured after the last administration. The pathological changes of rat kidney tissue were observed by HE staining. The degree of fibrosis was observed by Masson's staining and scored. The expression levels of TGF-β, α-SMA mRNA, and mir-129-5p in kidney were detected by qRT-PCR. HK-2 cells were treated with 5 ng/ml TGF-β to induce HK-2 cell fibrosis. The expression levels of TGF-β, α-SMA mRNA, and mir-129-5p in HK-2 cells were detected by qRT-PCR. TargetScan predicted the target gene of mir-129-5p, HK-2 cells were transfected with mir-129-5p mimic, and an overexpressed mir-129-5p HK-2 cell model was constructed. qRT-PCR was used to detect the expression of PDPK1 mRNA. Western blot was used to detect the expression of PDPK1, AKT, and p-AKT in HK-2 cells induced by TGF-β and in UUO rats.

Results

NDK mixture significantly reduced the 24-hour urine protein and CR levels of UUO rats. HE staining showed that the NDK mixture group exhibited a significantly reduced degree of renal interstitial fibrosis. NDK mixture also reduced the expression of TGF-β and α-SMA, and the middle-dose group showed a better therapeutic effect. In vitro studies showed that NDK mixture-containing serum increased the expression of mir-129-5p to reduce renal fibrosis. In addition, NDK mixture increased the expression of mir-129-5p in vivo. Further studies indicated that mir-129-5p could target PDPKl to reduce its expression. The NDK-containing serum group also exhibited reduced expression of PDPK1.

Conclusion

NDK mixture can significantly improve renal function and improve renal fibrosis in UUO model rats. Furthermore, NDK mixture can inhibit the expression of PDPK1 by upregulating the expression of mir-129-5p and then inhibiting the PI3K/AKT pathway to improve renal fibrosis.

Intermittent hypoxia causes histological kidney damage and increases growth factor expression in a mouse model of obstructive sleep apnea

Epidemiological studies demonstrate an association between obstructive sleep apnea (OSA) and accelerated loss of kidney function. It is unclear whether the decline in function is due to OSA per se or to other confounding factors such as obesity. In addition, the structural kidney abnormalities associated with OSA are unclear. The objective of this study was to determine whether intermittent hypoxia (IH), a key pathological feature of OSA, induces renal histopathological damage using a mouse model. Ten 8-week old wild-type male CB57BL/6 mice were randomly assigned to receive either IH or intermittent air (IA) for 60 days. After euthanasia, one kidney per animal was paraformaldehyde-fixed and then sectioned for histopathological and immunohistochemical analysis. Measurements of glomerular hypertrophy and mesangial matrix expansion were made in periodic acid–Schiff stained kidney sections, while glomerular transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF) and vascular endothelial growth factor-A (VEGF-A) proteins were semi-quantified by immunohistochemistry. The antigen-antibody reaction was detected by 3,3′-diaminobenzidine chromogen where the color intensity semi-quantified glomerular protein expression. To enhance the accuracy of protein semi-quantification, the percentage of only highly-positive staining was used for analysis. Levels of TGF-β, CTGF and VEGF-A proteins in the kidney cortex were further quantified by western blotting. Cellular apoptosis was also investigated by measuring cortical antiapoptotic B-cell lymphoma 2 (Bcl-2) and apoptotic Bcl-2-associated X (Bax) proteins by western blotting. Further investigation of cellular apoptosis was carried out by fluorometric terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) staining. Finally, the levels of serum creatinine and 24-hour urinary albumin were measured as a general index of renal function. Our results indicate that mice exposed to IH have an increased glomerular area (by 1.13 fold, p< 0.001) and expansion of mesangial matrix (by 1.8 fold, p< 0.01). Moreover, the glomerular expressions of TGF-β1, CTGF and VEGF-A proteins were 2.7, 2.2 and 3.8-fold higher in mice exposed to IH (p< 0.05 for all). Furthermore, western blotting protein analysis demonstrates that IH-exposed mice express higher levels of TGF-β1, CTGF and VEGF-A proteins by 1.9, 4.0 and 1.6-fold (p< 0.05 for all) respectively. Renal cellular apoptosis was greater in the IH group as shown by an increased cortical Bax/Bcl-2 protein ratio (p< 0.01) and higher fluorometric TUNEL staining (p< 0.001). Finally, 24-hr urinary albumin levels were higher in mice exposed to IH (43.4 μg vs 9.7 μg, p< 0.01), while there were no differences in serum creatinine levels between the two groups. We conclude that IH causes kidney injury that is accompanied by glomerular hypertrophy, mesangial matrix expansion, increased expression of glomerular growth factors and an increased cellular apoptosis.

Morphological characterization of ckd in cats: Insights of fibrogenesis to be recognized

Renal fibrosis is characterized by glomerulosclerosis and tubulointerstitial fibrosis and its pathogenesis is associated with the activity of mesenchymal cells (fibroblasts), being essentially characterized by a process of excessive accumulation resulting from the deposition of extracellular matrix components. The aim of this study was to characterize the morphological presentation of chronic and fibrotic lesions in the glomerular, tubular, interstitial, and vascular compartments in feline CKD, as well as the possible participation of myofibroblasts in renal fibrotic processes in this species. Cat kidneys were collected and processed according to the conventional techniques for light microscopy, circular polarization, immunohistochemistry, and electron microscopy. Fibrotic alterations were present in all compartments analyzed. The main findings in the glomerular compartment were different degrees of glomerular sclerosis, synechia formation, Bowman's capsule calcification, in addition to glomerular basement membrane thickening and pericapsular fibrosis. The tubulointerstitial compartment had intense tubular degeneration and the immunostaining in tubular cells for mesenchymal cell markers demonstrated the possibility of mesenchymal epithelial transition and consequent involvement of myofibroblasts in the development of interstitial tubule damage. Infiltration of inflammatory cells, added to vessel thickening and fibrosis, demonstrated the severity and role of inflammation in the development and perpetuation of damage. Thus, we may conclude that fibrotic lesions play a relevant role in feline CKD and the mechanism of perpetuation of these lesions need further elucidation regarding the origin and participation of myofibroblasts and consequent mesenchymal epithelial transition in this species.

Targeting TGF-β Mediated SMAD Signaling for the Prevention of Fibrosis

Fibrosis occurs when there is an imbalance in extracellular matrix (ECM) deposition and degradation. Excessive ECM deposition results in scarring and thickening of the affected tissue, and interferes with tissue and organ homeostasis – mimicking an exaggerated “wound healing” response. Many transforming growth factor-β (TGF-β) ligands are potent drivers of ECM deposition, and additionally, have a natural affinity for the ECM, creating a concentrated pool of pro-fibrotic factors at the site of injury. Consequently, TGF-β ligands are upregulated in many human fibrotic conditions and, as such, are attractive targets for fibrosis therapy. Here, we will discuss the contribution of TGF-β proteins in the pathogenesis of fibrosis, and promising anti-fibrotic approaches that target TGF-β ligands.

miR-150 promotes renal fibrosis in lupus nephritis by downregulating SOCS1

MicroRNAs (miRs) seem to mediate renal fibrosis in several renal diseases, with some miRs having profibrotic effects and others having opposing effects. Although differential expression of certain miRs has been described in lupus nephritis, it is unknown whether miRs contribute to fibrosis or could serve as biomarkers of specific histologic manifestations of lupus nephritis. Here, we compared miR expression in kidney biopsies from patients with lupus nephritis and identified miR-150 as the most differentially expressed miR in kidneys with high chronicity (chronicity index [CI] ≥ 4); miR-150 positively correlated with chronicity scores and the expression of profibrotic proteins. Overexpression of miR-150 significantly reduced expression of the antifibrotic protein suppressor of cytokine signaling 1 (SOCS1) and upregulated profibrotic proteins in both proximal tubular and mesangial cells. Directly targeting SOCS1 with a small interfering RNA produced similar results. Furthermore, TGF-β1 induced miR-150 expression, decreased SOCS1, and increased profibrotic proteins in proximal tubular cells and podocytes; a miR-150 inhibitor reversed these changes, suggesting that the profibrotic effects of TGF-β1 are, at least in part, mediated by miR-150. Consistent with these in vitro observations, biopsies with high miR-150 and high CI exhibited substantial expression of TGF-β1, reduced SOCS1, and an increase in profibrotic proteins. In summary, miR-150 is a promising quantitative renal biomarker of kidney injury in lupus nephritis. Our results suggest that miR-150 promotes renal fibrosis by increasing profibrotic molecules through downregulation of SOCS1.

Renal macrophage infiltration is associated with a poor outcome in IgA nephropathy

OBJECTIVES

The objectives of our study were as follows: 1) to analyze the prognostic value of macrophage infiltration in primary IgA nephropathy (IgAN) and 2) to study the relationship between macrophages and other factors associated with the development of renal fibrosis, including mast cells, TGF-β1, α-SMA and NF-kB.

METHODS

We analyzed 62 patients who had been diagnosed with IgAN between 1987 and 2003. Immunohistochemical staining was performed with monoclonal antibodies against CD68 and mast cell tryptase and polyclonal antibodies against TGF-β1, α-SMA and NF-kB p65. We also used Southwestern histochemistry for the in situ detection of activated NF-kB.

RESULTS

The infiltration of macrophages into the tubulointerstitial compartment correlated with unfavorable clinical and histological parameters, and a worse clinical course of IgAN was significantly associated with the number of tubulointerstitial macrophages. Kaplan-Meier curves demonstrated that increased macrophage infiltration was associated with decreased renal survival. Moreover, the presence of macrophages was associated with mast cells, tubulointerstitial α-SMA expression and NF-kB activation (IH and Southwestern histochemistry). In the multivariate analysis, the two parameters that correlated with macrophage infiltration, proteinuria and tubulointerstitial injury, were independently associated with an unfavorable clinical course.

CONCLUSION

An increased number of macrophages in the tubulointerstitial area may serve as a predictive factor for poor prognosis in patients with IgAN, and these cells were also associated with the expression of pro-fibrotic factors.

Detection of multiple cytokines in the urine of patients with focal necrotising glomerulonephritis may predict short and long term outcome of renal function

BACKGROUND

Detection of urinary cytokines in pauci-immune focal segmental necrotizing glomerulonephritis (FSNGN) may provide valuable information about disease pathogenesis and prognosis.

METHODS

Epidermal growth factor (EGF), transforming growth factor (TGF-β1) and vascular endothelial growth factor (VEGF) were measured by ELISA, and Interleukins, monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein (MIP1β) by a multiplex cytokine assay, in 38 patients with FSNGN. Their levels were correlated with severity of histological findings and renal function outcome in short and long term.

RESULTS

The percentage of crescents in renal biopsy had positive correlation with TGF-β1 (p=0.004) and IL-15 urinary excretion (p=0.01), and negative correlation with EGF (p=0.01). Increased urinary excretion of IL-6, IL-15, VEGF and MIP-1β was associated with poor renal function outcome, but increased levels of EGF, IL-2 and IL-9 predicted a favourable prognosis. In multiple regression analysis IL-6 and VEGF urinary levels were independent predictors of no-response at the acute phase (p=0.001 and p<0.0001, respectively), while, IL-6 was the only factor (p=0.03) predicted worse outcome at the end of follow-up (39.4±45 months).

CONCLUSION

Increased urinary excretion of IL-6, IL-15, VEGF, TGF-β1, MCP-1 and MIP-1β and reduced EGF, IL-2, IL-9 may be associated with histological damage and influence response to treatment in pauci-immune FSNGN.

Comparative healing of rat fascia following incision with three surgical instruments

BACKGROUND

Incisional hernia and fascial dehiscence are associated with significant postoperative morbidity. Electrosurgical devices using pulsed radiofrequency energy and a novel electrode design markedly reduce thermal injury during cutting and coagulation while maintaining equal surgical performance. In this study, we examine fascial healing dynamics in a rat model following incision with a pulsed radiofrequency energy device (PRE), a conventional electrosurgical device, and a standard "cold" scalpel. We hypothesize that incisions made with the pulsed radiofrequency energy device will result in a superior fascial healing profile compared with conventional electrosurgery.

MATERIALS AND METHODS

Full thickness surgical incisions were created in rat fascia using a commercially available PRE device, conventional electrosurgery, and a scalpel. Harvested fascial specimens were analyzed for burst strength testing and healing-associated histologic characteristics at d 7, 14, 21, and 42.

RESULTS

PRE incisions were fully healed by 6 wk with normal tissue architecture. By all measures, wounds created by the PRE device were comparable to those made with the standard scalpel. Compared with PRE, conventional electrosurgery incisions exhibited a larger zone of tissue injury (68% greater in Coag mode, P < 0.0001; 46% greater in Cut mode, P < 0.001), an increased inflammatory response and a less favorable wound architecture. In the immediate postoperative period (1 wk), burst strength testing demonstrated that PRE fascial wounds were significantly stronger than those made by electrosurgery in Coag mode (318%, P = 0.001).

CONCLUSIONS

The favorable fascial healing profile of the PRE device suggests that it is a promising new surgical technology. The early improved strength of wounds made with this device is of particular interest, as wound dehiscence is of greatest concern early in the healing process.

Transglutaminase inhibition ameliorates experimental diabetic nephropathy

Diabetic nephropathy is characterized by excessive extracellular matrix accumulation resulting in renal scarring and end-stage renal disease. Previous studies have suggested that transglutaminase type 2, by formation of its protein crosslink product epsilon-(gamma-glutamyl)lysine, alters extracellular matrix homeostasis, causing basement membrane thickening and expansion of the mesangium and interstitium. To determine whether transglutaminase inhibition can slow the progression of chronic experimental diabetic nephropathy over an extended treatment period, the inhibitor NTU281 was given to uninephrectomized streptozotocin-induced diabetic rats for up to 8 months. Effective transglutaminase inhibition significantly reversed the increased serum creatinine and albuminuria in the diabetic rats. These improvements were accompanied by a fivefold decrease in glomerulosclerosis and a sixfold reduction in tubulointerstitial scarring. This was associated with reductions in collagen IV accumulation by 4 months, along with reductions in collagens I and III by 8 months. This inhibition also decreased the number of myofibroblasts, suggesting that tissue transglutaminase may play a role in myofibroblast transformation. Our study suggests that transglutaminase inhibition ameliorates the progression of experimental diabetic nephropathy and can be considered for clinical application.

Beneficial effect of triple treatment plus immunoglobulin in experimental nephrotic syndrome

Combinations of antiproteinurics, including angiotensin I-converting enzyme inhibitors + angiotensin II receptor antagonist + statins, are promising choices in the treatment of steroid-resistant nephrotic syndrome. We aimed to investigate the effects of high doses of immunoglobulin in addition to these combinations in rats with adriamycin-induced nephrosis. The study included 40 rats allocated into five groups: control, nephrotic syndrome without treatment, dual therapy (DT) with enalapril + losartan, triple therapy (TT) with enalapril + losartan + simvastatin, and quadruple therapy (QT) with enalapril + losartan + simvastatin + a high dose of immunoglobulin. The proteinuria levels were not statistically different between DT, TT and QT groups at weeks 5, 8, 12 and 16. At week 16, serum creatinine levels in the QT group were significantly lower than those in the control, DT and TT groups. The glomerulosclerosis index in the DT group was significantly lower than in the TT and QT groups. The scores for interstitial fibrosis and TGF-beta staining were similar among treatment groups. In conclusion, we showed that quadruple therapy including immunoglobulin had a beneficial effect on renal function in the late phase, but it had no additional effects in reducing proteinuria or in glomerulosclerosis score in experimental nephrotic syndrome. Further studies with angiotensin I-converting enzyme inhibitors (ACEIs), angiotensin II receptor antagonists (AIIRAs) and immunoglobulin combinations would offer some benefits in the treatment of nephrotic syndrome.

Renal expression of galectin-3 in systemic lupus erythematosus patients with nephritis

The aim of the study is to characterize the expression pattern of galectin-3 (Gal-3) in renal tissues of patients with systemic lupus erythematosus (SLE) nephritis and to determine whether tissue and serum Gal-3 are associated with SLE nephritis. Gal-3 expressions were examined with immunohistochemistry in renal biopsy specimens of 88 patients with SLE nephritis and in five normal specimens. Activity and chronicity indexes and glomerular Gal-3 expressions were analysed in each specimen. Serum Gal-3 levels were measured using enzyme-linked immunosorbent assays in 20 patients with SLE, including 11 with nephritis, and in 50 healthy controls. Glomerular Gal-3 expression was observed in 81.8% (72/88) of patients with SLE nephritis but not in 5 controls. Gal-3 staining was attributed mainly to its cellular expression rather than its deposition, and Gal-3 expression levels were correlated with histologic activity indexes, anti-dsDNA titers, and complement 3 and 4 levels. Serum Gal-3 levels were higher in patients with SLE, particularly in those with nephritis, than in healthy controls, and correlated with anti-dsDNA titers. In conclusion, glomerular Gal-3 expression in renal tissue and serum Gal-3 levels were elevated in patients with SLE nephritis versus healthy controls; moreover, they reflected disease activity. These findings suggest that Gal-3 might contribute to the inflammatory process in SLE.

Connective tissue growth factor stimulates renal cortical myofibroblast-like cell proliferation and matrix protein production

Myofibroblasts primarily contribute to the pathogenesis of renal interstitial fibrosis by unregulated cell proliferation and synthesis of excessive amounts of extracellular matrix (ECM) proteins. We used cultured myofibroblast-like cells obtained by outgrowth from explants of rat kidney cortex to study the effects and relevant signaling pathway of connective tissue growth factor (CTGF) on cell proliferation and ECM production. Exogenous CTGF stimulated proliferation of myofibroblast-like cells in a dose- and time-dependent manner. CTGF also increased the secretion of fibronectin and collagen I protein in the supernatant medium. Nevertheless, CTGF did not affect matrix-degrading metalloproteinases-2 and -9 activities in supernatant medium measured by gelatin zymography. CTGF induced activation of extracellular signal-regulated protein kinase (ERK)1/2 mitogen-activated protein kinase pathway as early as 5 minutes. Inhibition of ERK1/2 activation with PD98059 completely blocked CTGF-induced cell proliferation as well as secretion of fibronectin and collagen I protein. The above results indicate that CTGF triggers cell proliferation and production of ECM proteins in cultured myofibroblast-like cells through the ERK1/2 mitogen-activated protein kinase pathway.

Signaling pathways modulated by fish oil in salt-sensitive hypertension

Although many studies have indicated that fish oil (FO) improves cardiovascular risk factors and reduces histopathological manifestations of injury in experimental renal injury models, potential mechanisms underlying this protective effect have not been adequately defined. The objective of this study was to identify potential signaling pathways that confer protection in the Dahl rat model of salt-sensitive hypertension. Male Dahl salt-sensitive rats (n = 10/group) were provided with formulated diets containing 8% NaCl, 20% protein, and 25% FO or 25% corn oil (CO) for 28 days. FO reduced blood pressure (-11% at 4 wk; P < 0.05), urine protein excretion (-45% at 4 wk; P < 0.05), plasma cholesterol and triglyceride levels (-54%, P < 0.001; and -58%, P < 0.05), and histopathological manifestations of renal injury, including vascular hypertrophy, segmental and global glomerular sclerosis, interstitial fibrosis, and tubular atrophy. Interstitial inflammation was significantly reduced by FO (-32%; P < 0.001), as assessed by quantitative analysis of ED1-positive cells in sections of the renal cortex. FO reduced tubulointerstitial proliferative activity, as assessed by Western blot analysis of cortical homogenates for PCNA (-51%; P < 0.01) and quantitative analysis of Mib-1-stained sections of the renal cortex (-42%; P < 0.001). Decreased proliferative activity was associated with reduced phospho-ERK expression (-37%; P < 0.005) and NF-kappaB activation (-42%; P < 0.05). FO reduced cyclooxygenase (COX)-2 expression (-63%; P < 0.01) and membrane translocation of the NADPH oxidase subunits p47(phox) and p67(phox) (-26 and -34%; P < 0.05). We propose that FO ameliorates renal injury in Dahl salt-sensitive rats through the inhibition of ERK, decreased NF-kappaB activation, inhibition of COX-2 expression, and decreased NADPH oxidase activation.

TGF-beta-induced fibrosis and SMAD signaling: oligo decoys as natural therapeutics for inhibition of tissue fibrosis and scarring

Transforming-growth factor-beta (TGF-beta) is a pleiotrophic growth factor that is synthesized by many cells in the body. This growth factor is chemotactic for fibroblasts, stimulates fibroblast proliferation, and increases the synthesis of a number of extracellular matrix proteins including collagens. The TGF-beta activator protein is a transacting factor, which binds to the TGF-beta element in the distal promoter of the COL1A1 collagen gene and induces transcription of this gene. Although transient TGF-beta 1 activity participates in repair and regeneration of tissues, persistent TGF-beta 1 function affects excessive fibrosis and ultimately scarring of both skin and internal organs. Scarring of internal organ (e.g., liver and lung) results in a loss of function and ultimately death may occur. The central issue of this review is that phosphorothioate double-stranded decoys or other decoys decrease procollagen gene expression, procollagen synthesis, and collagen during fibrogenesis. The rationale is that the decoys containing the TGF-beta element or other gene transcription regulatory CIS-elements bind the transacting proteins preventing the latter from binding to the CIS-element in the 5'-flanking region of the natural gene resulting in transcription inhibition. We will, in part, focus on aspects involved in TGF-beta 1-induced fibrosis that occur during fibrogenesis and the use of the dsTGF-beta element containing oligodeoxynucleotide decoys to control excessive collagen synthesis, and deposition resulting from persistent TGF-beta. In our model of regulation of collagen synthesis, these double-stranded oligo decoys act as promoter competitors, binding to the activator protein either in the cytoplasm or in the nucleus. The significance of the proposed studies is that these novel natural antifibrotics will mimic the effect of glucocorticoids on collagen synthesis during fibrogenesis without the unwanted side effects of these steroids. Based on our previous studies on the molecular mechanisms by which glucocorticoids selectively decrease collagen synthesis, designed phosphorothioate oligodeoxynucleotides resistant to nuclease action will mimic the effects of glucocorticoids at the molecular, cellular, and in vivo levels of collagen synthesis. However, the glucocorticoids significantly inhibit noncollagen protein synthesis. Both the single-stranded and double-stranded oligodeoxynucleotide specifically decrease collagen synthesis without an inhibitory effect on noncollagen protein synthesis. In this review, we will specifically ask if TGF-beta-induced collagen synthesis is inhibited in cell culture and in vivo by using the double-stranded oligodeoxynucleotide decoys, will this inhibit fibrogenesis and ultimately scarring?

Histological, immunohistochemical and biological data in assessing interstitial fibrosis in patients with chronic glomerulonephritis

The aim of this study was to determine the relationship between histological, immunohistochemical (IHC) and biological data in the assessment of interstitial fibrosis in patients with glomerular diseases. A group of 41 patients with primary and secondary glomerulonephritis was studied. In order to quantify the histological changes and to assess the extent of active-inflammatory and chronic-sclerotic/fibrotic interstitial lesions, we adapted a scoring system, initially used for lupus nephritis, and ANCA-associated vasculitis. IHC labeling procedures with monoclonal antibodies anti-smooth muscle actin (SMA), anti-vimentin and anti-transforming growth factor beta (TGFbeta) were assessed using a semi-quantitative score, correlated with the histological and biological data. Our results showed that interstitial labeling of SMA correlated with scores for sclerotic/fibrotic lesions (chronicity index) and with active-inflammatory lesions (interstitial infiltrate, activity index). Interstitial vimentin correlated with the score for interstitial infiltrate. Both interstitial vimentin and TGFbeta immunopositivity correlated with sclerotic/fibrotic lesions (interstitial fibrosis, tubular atrophies, vascular hyalinosis/fibrosis, chronicity index), and negatively with glomerular filtration rate. An important correlation was found between the interstitial labeling of the two IHC markers of myofibroblasts (SMA and vimentin). We conclude that IHC studies related to clinico-biological and histological data can have an important role in the evaluation of the glomerular diseases, but the classical histological investigation assessed through quantification has still not lost its importance.

Oral administration of GW788388, an inhibitor of TGF-beta type I and II receptor kinases, decreases renal fibrosis

Progressive kidney fibrosis precedes end-stage renal failure in up to a third of patients with diabetes mellitus. Elevated intra-renal transforming growth factor-beta (TGF-beta) is thought to underlie disease progression by promoting deposition of extracellular matrix and epithelial-mesenchymal transition. GW788388 is a new TGF-beta type I receptor inhibitor with a much improved pharmacokinetic profile compared with SB431542. We studied its effect in vitro and found that it inhibited both the TGF-beta type I and type II receptor kinase activities, but not that of the related bone morphogenic protein type II receptor. Further, it blocked TGF-beta-induced Smad activation and target gene expression, while decreasing epithelial-mesenchymal transitions and fibrogenesis. Using db/db mice, which develop diabetic nephropathy, we found that GW788388 given orally for 5 weeks significantly reduced renal fibrosis and decreased the mRNA levels of key mediators of extracellular matrix deposition in kidneys. Our study shows that GW788388 is a potent and selective inhibitor of TGF-beta signalling in vitro and renal fibrosis in vivo.

Effects of tripterine on mRNA expression of TGF-beta1 and collagen IV expression in BW F1 mice

Tripterine is a chemical isolated from a traditional Chinese herb which had been testified for its anti-inflammatory and immunosuppressive activities in a previous study. However, little is known about the effects and mechanism of action of Tripterine on treating lupus nephritis. In the present study we investigated the effect of Tripterine on the F1 hybrids of New Zealand Black (NZB) and New Zealand White (NZW) mice which functioned as a model of human systemic lupus erythematosus (BW F1 mice) and evaluated the possible mechanism implicated in the mRNA expression of TGF-beta1 and collagen IV expression of the BW F1 mice kidney tissue. Different doses of Tripterine were injected peritoneally to BW F1 mice at different stages to study the preventive effects of Tripterine on lupus nephritis glomerulosclerosis and its mechanisms. Twenty-four hour urine protein excretion, serum anti-dsDNA antibodies and the expression of collagen type IV were examined by immunohistochemistry while the expression of TGF-beta1 mRNA was detected by RT nested PCR. Tripterine decreased urine protein excretion and the level of serum anti-dsDNA antibodies and also suppressed the expression of collagen type IV and TGF-beta1 mRNA in the murine kidney tissue. Administration of Tripterine before the occurrence of proteinuria had much greater protective effects than if it was administered after the occurrence of proteinuria. No significant difference was found between the 3 mg/kg/week Tripterine-treated-group and the 6 mg/kg/week Tripterine-treated-group. Tripterine had a definite protective effect on glomerulosclerosis of the lupus murine model. Tripterine could significantly reduce the amount of urine protein excretion, suppress the formation of serum anti-dsDNA antibodies, it could also efficiently decrease the expression of renal collagen type IV probably due to its suppressive effect on the expressions of local TGF-(1 mRNA) in this model.

Apoptosis of tubulointerstitial chronic inflammatory cells in progressive renal fibrosis after cancer therapies

Progressive renal fibrosis is an unwanted and limiting side effect of cancer treatments, whether they are systemic (for example, chemotherapy), local (for example, radiotherapy), or total body irradiation for allogenic bone marrow transplants. The relative roles of macrophages, myofibroblasts, and lymphocytes and the apoptotic deletion of renal functional or inflammatory cell populations in the pathogenesis of renal fibrosis are yet unclear. In this study, rat models of 2 renal cancer treatments: cis-platinum-(II)-diammine dichloride (cisplatin, 6-mg/kg body weight) and radiation (single dose of 20 Gy) were used. Kidneys were analyzed 4 days to 3 months after treatment. The extent of renal fibrosis was compared with number and localization of chronic inflammatory cell populations, cell death (apoptosis and necrosis), and expression and localization of profibrotic growth factors transforming growth factor-beta1 (TGF-beta1) and tumor necrosis factor-alpha (TNF-alpha). The models provided contrasting rates of fibrogenesis: After cisplatin, development of fibrosis was rapid and extensive (up to 50% fibrosis at 3 months); in comparison, radiation-induced fibrosis was slowly progressive (approximately 10% fibrosis at 3 months). The extent of fibrosis was associated spatially and temporally with increasing numbers of myofibroblasts with TGF-beta1 or macrophages with TNF-alpha. Tubular epithelial apoptosis was highest with high TNF-alpha (P<0.05). A significant inverse correlation existed between extent of tubulointerstitial fibrosis and interstitial cell apoptosis for cisplatin and a similar nonsignificant result for radiation (r(2)=0.8671 for cisplatin, P<0.05; r(2)=0.2935 for radiation, NS). The latter result suggests a role for inflammatory cell apoptosis in minimizing development of renal fibrosis.

Dysregulated growth factor gene expression is associated with tubulointerstitial apoptosis and renal dysfunction

Chronic renal disease is characterized by declining renal function, loss of intrinsic renal cells, and their replacement with fibrotic tissue. This study investigates apoptosis and its regulation in the context of chronic renal disease. RNA was extracted from renal biopsies from patients with various forms of chronic renal disease. Expression of genes of the Bcl-2 family, death receptor pathway, and growth factors were measured by reverse-transcription real-time polymerase chain reaction. Apoptosis was detected by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling technique. Tubulointerstitial apoptosis was positively associated with tubulointerstitial injury and renal dysfunction and increased 2.3-fold per unit (U) increase in transforming growth factor beta(1) (TGFbeta(1)) mRNA (P<0.05). Conversely, a 1 U increase in epidermal growth factor (EGF) mRNA was associated with a 47% decrease in tubulointerstitial apoptosis (P<0.05). Tubulointerstitial injury was correlated with increased TGFbeta(1) and tumour necrosis factor alpha (TNFalpha) mRNA (P<0.005) and decreased EGF mRNA (P<0.05). Additionally, for a 10 U decrease in the glomerular filtration rate there was an estimated increase of 5 and 10% in TGFbeta(1) and TNFalpha mRNA, respectively (P<0.05), whereas EGF mRNA decreased by an estimated 15% (P<0.005). Therefore dysregulation of cytokine/growth factor expression plays a central role in the progression of chronic renal disease through contribution to renal cell loss, tubulointerstitial injury, and renal dysfunction.

A comparison of pathomolecular markers of fibrosis and morphology in kidney from autopsies of African Americans and whites

African Americans have an increased incidence of chronic kidney disease (CKD) due to hypertension and arteriosclerosis and increased death due to coronary artery disease, compared with whites. The pathogenesis of CKD involves the increased presence and activation of myofibroblasts and macrophages, promotion of tubulointerstitial fibrosis, and effects of tubulointerstitial cell mitosis and apoptosis. We hypothesized that increased risk of hypertensive vascular disease may be identified by renal pathomolecular markers that are associated with progressive CKD. Renal sections were available from 50 autopsies of 33 African Americans (55% males) and 17 whites (76% males) undergoing forensic autopsy for unexpected death. Sclerotic glomeruli, severity of cortical fibrosis, and renal arteriolosclerosis, total glomerular number (N (glom)), average glomerular volume (V (glom)), birth weights, and blood pressure were known. Presence and locality of markers for myofibroblasts (alpha-SMA), macrophages (CD68), collagen, pro-fibrotic transforming growth factor-beta1 were scored in renal autopsies, and tubulointerstitial apoptosis was recorded. The results demonstrated a strong positive correlation between age, cortical fibrosis and alpha-SMA (p<0.05), and between CD68 and hypertension and coronary artery disease (p<0.05). The findings confirm the role of myofibroblasts and macrophages in pathogenesis of human CKD. However, the markers showed no significant relationships to V (glom), N (glom), birth weight, or race.

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.

Correlative insights into the immunoexpression of transforming growth factor β-1 in acutely rejected renal allografts

Recent data suggest that early changes in the process of acute renal transplant rejection (ARTR) occurring during the first 3 months after transplantation include interstitial fibrosis. Transforming growth factor beta (TGF-beta) has been recognized as a key mediator of renal fibrogenesis; therefore, the present study was conducted to ascertain immunoexpression of TGF-beta in ARTR. Another purpose of our study was to determine whether TGF-beta could correlate with the interstitial area and to examine a possible relationship between TGF-beta and interstitial alpha-smooth muscle actin (alpha-SMA), endothelin-1 (ET-1) expression, interstitial T lymphocytes, and monocytes/macrophages. Twenty-four renal allograft biopsy specimens obtained from patients with ARTR were examined using percutaneous renal biopsy. As a control, we used 11 allograft biopsy specimens obtained from patients without any sign of rejection. Staining intensities of TGF-beta-1 in tubuli and of ET-1 in the endothelium of peritubular capillaries, in arterioles, and in the renal tubular epithelial cells were recorded semiquantitatively, whereas interstitial CD3+ cells, CD68+ cells, alpha-SMA expression, and the interstitial area were assessed quantitatively using computer image analysis system. Our study revealed that in the ARTR group, the mean values of the immunoexpression of TGF-beta-1, ET-1, interstitial CD3+ cells, CD68+ cells, alpha-SMA expression, and the interstitial area were significantly increased as compared with controls. In the ARTR group, there were significant positive correlations between immunostaining of TGF-beta-1 and ET-1, immunostaining of TGF-beta-1 and alpha-SMA, as well as immunostaining of TGF-beta-1 and interstitial volume. The correlation between immunostaining of TGF-beta-1 and CD 3+ cells tended to be negative; however, this did not reach statistical significance. We did not find any significant relationship between TGF-beta-1 and interstitial monocytes/macrophages. In controls, all these correlations were not significant. In conclusion, our correlative study suggests a role of TGF-beta-1 in early interstitial fibrotic changes in acutely rejected renal allografts, and we hypothesize that endothelin-1 and myofibroblasts pathways may play an important role in this process.

Urinary Transforming Growth Factor-beta 1 as a marker of response to immunosuppressive treatment, in patients with crescentic nephritis

BACKGROUND

Crescentic nephritis is characterized by formation of cellular crescents that soon become fibrotic and result in irreversible damage, unless an effective immunosuppressive therapy is rapidly commenced. TGF-beta1 is involved in the development of crescents through various pathways. The aim of this study was to identify whether the determination of urinary TGF-beta1 levels in patients with crescentic nephritis could be used as a marker of response to treatment.

METHODS

Fifteen patients with crescentic nephritis were included in the study. The renal expression of TGF-beta1 was estimated in biopsy sections by immunohistochemistry and urinary TGF-beta1 levels were determined by quantitative sandwich enzyme immunoassay (EIA). TGF-beta1 levels were determined at the time of renal biopsy, before the initiation of immunosuppressive treatment (corticosteroids, cyclophosphamide and plasma exchange). Twelve patients with other types of proliferative glomerulonephritis and ten healthy subjects were used as controls.

RESULTS

Improvement of renal function with immunosuppressive therapy was observed in 6 and stabilization in 4 patients (serum creatinine from 3.2 +/- 1.5 to 1.4 +/- 0.1 mg/dl and from 4.4 +/- 1.2 to 4.1 +/- 0.6 mg/dl, respectively). In 5 patients, with severe impairment of renal function who started on dialysis, no improvement was noted. The main histological feature differentiating these 5 patients from others with improved or stabilized renal function was the percentage patients with poor response to treatment were the percentage of glomeruli with crescents and the presence of ruptured Bowman's capsule and glomerular necrosis. Urinary TGF-beta1 levels were significantly higher in patients who showed no improvement of renal function with immunosuppressive therapy (930 +/- 126 ng/24 h vs. 376 +/- 84 ng/24 h, p < 0.01). TGF-beta1 was identified in crescents and tubular epithelial cells, whereas a significant correlation of TGF-beta1 immunostaining with the presence of fibrocellular cresents was observed (r = 0.531, p < 0,05).

CONCLUSION

Increased TGF-beta1 renal expression and urinary excretion that is related to the response to immunosuppressive therapy was observed in patients with crescentic nephritis. Evaluation of urinary TGF-beta1 levels may be proved a useful marker of clinical outcome in patients with crescentic nephritis.

The study of Chinese medicinal herbal formula Shen San Fang in the treatment of experimental IgA nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide, yet there is no effective or specific therapy. Shen San Fang (S3F) is a traditional Chinese herbal medicinal formula that has been used in China for many years to treat patients with hematuria. The aim of this study is to test the therapeutic value of S3F in an experimental model of IgAN. IgAN was induced in Lewis rats by continuous oral immunization with bovine gamma-globulin (BGG) in the drinking water for 8 weeks, followed by intravenous injection of 1 mg BGG daily for 3 successive days. The rats were randomly divided into four groups (five rats/group): control, control receiving S3F, induction of IgAN, and IgAN receiving S3E S3F decoction was fed to rats beginning week 4 from the first day of oral sensitization with BGG. The S3F treatment was continued until the rats were sacrificed or for a 4-week period. Hematuria, renal immunohistochemistry for IgA and transforming growth factor-beta 1 (TGF-beta1), renal histopathology, and renal content of TGF-beta1 were measured. Rats developing IgAN had marked hematuria, profound mesangial proliferation and mesangial expansion, intense and diffuse glomerular IgA deposition, increased glomerular TGF-beta1 expression, and raised renal TGF-beta1 levels. S3F treatment resulted in a significant reduction of hematuria, decreased mesangial IgA deposition, weaker immunostaining of TGF-beta1 in glomerulus, and a lower renal TGF-beta1 concentration. Our animal data suggests a therapeutic value for the Chinese medicinal formula S3F in experimental IgAN. This beneficial effect was due to reduced glomerular IgA deposition and TGF-beta1 expression. Our preliminary findings hold promise for future human therapy.

Fluvastatin reduces renal fibroblast proliferation and production of type III collagen: therapeutic implications for tubulointerstitial fibrosis

BACKGROUND

Accumulating evidence suggests that hydroxymethylglutaryl-CoA reductase inhibitors have many biological effects beyond reducing cholesterol synthesis. In a mouse model of renal interstitial fibrosis induced by unilateral ureteral obstruction, fluvastatin, one of the lipophilic hydroxymethylglutaryl-CoA reductase inhibitors, was shown to ameliorate fibrosis.

METHODS

In the present study, we examined the direct effects of fluvastatin on proliferation, matrix and growth factor production by rat kidney fibroblasts (NRK-49F cells).

RESULTS

Treatment with fluvastatin reduced proliferation of NRK-49F cells in a dose-dependent manner. The addition of mevalonate or geranylgeranyl pyrophosphate but not farnesyl pyrophosphate to the culture medium almost completely abolished the effect of fluvastatin. Moreover, fluvastatin treatment decreased the expression of activated Rho in NRK-49F cells suggesting that fluvastatin may decrease cell growth through blocking the activation of Rho. The majority of fluvastatin-treated cells were arrested at the G1 phase, associated with down-regulation of cyclin A and up-regulation of cyclin-dependent kinase inhibitor p27kip1, indicating that cell cycle modulation is an important mechanism. Fluvastatin significantly decreased messenger RNA expression of type III collagen and connective tissue growth factor.

CONCLUSIONS

Taken together, it is suggested that fluvastatin may prevent tubulointerstitial fibrosis in a variety of progressive renal diseases by inhibiting proliferation of interstitial fibroblasts and their matrix synthesis.

Transforming growth factor-beta1 in nephrotic syndrome treated with cyclosporine and ACE inhibitors

The aim of the study was to assess urinary transforming growth factor (TGF)-beta1 in children with steroid-dependent nephrotic syndrome (SDNS) treated with cyclosporine A (CyA) and ACE inhibitors (ACEI). The study involved 24 children (14 boys and 10 girls) with SDNS and signs of focal segmental glomerulosclerosis. The children were treated with prednisone, CyA, and ACEI. All children were examined four times: A during relapse of proteinuria, before treatment with CyA and ACEI, and B after 3 months, C 6 months, and D 12 months of treatment. The control group consisted of 20 healthy children of the same age. The urinary TGF-beta1 level was determined by ELISA (R and D Quantikine). The serum CyA level was measured by monoclonal antibody fluorescence polarization immunoassay. Prior to CyA treatment, the urinary TGF-beta1 level was the highest (135.61+/-38.31 pg/mg creatinine). During CyA treatment, TGF-beta1 was reduced to 117.96+/-81.57 after 3 months, to 80.26+/-49.52 after 6 months, and to 44.00+/-31.83 pg/mg creatinine after 12 months, but it was still higher than in the control group. At 3 months there was a positive linear correlation between urinary TGF-beta1 and proteinuria (r=0.654, P<0.01). These results indicate that the urinary TGF-beta1 level increases in proportion to proteinuria during relapse of NS. Treatment with CyA and ACEI also influences urinary TGF-beta1, which is still higher after 12 months of treatment than in healthy children.

Effects of Hochu‐ekki‐to and Ninjin‐youei‐to, Traditional Japanese Medicines, on Porcine Serum‐Induced Liver Fibrosis in Rats

In this study, we estimated the effects of traditional Japanese medicines on liver fibrosis in Wistar rats injected with porcine serum twice a week for 8 weeks. The rats were orally administered Hochu-ekki-to, Ninjin-youei-to (100 and 300 mg/kg/day) or Sho-saiko-to (300 mg/kg/day) 5 days per week. Serum and liver samples were obtained 2 days after the last porcine serum injection. Hochu-ekki-to and Ninjin-youei-to showed significant suppressive effects on the increase in hepatic hydroxyproline, namely total collagen. Further, Ninjin-youei-to significantly suppressed the increases of type IV collagen localized in the basement membrane and prolyl 4-hydroxylase, a collagen synthesis enzyme, in serum or liver. Hochu-ekki-to showed a similar trend. Although Sho-saiko-to did not significantly suppress the increase in hepatic hydroxyproline, it intensely suppressed serum type IV collagen. Further, Hochu-ekki-to, Ninjin-youei-to, and Sho-saiko-to inhibited the production of fibrogenic cytokines, namely TGF-beta1 and IL-13, in the serum and liver. Additionally, we showed that IL-13 levels were positively correlated with hydroxyproline contents in the liver. These results suggest that Ninjin-youei-to as well as Hochu-ekki-to suppress porcine serum-induced liver fibrosis more effectively than Sho-saiko-to. The effects of these three medicines probably depend on the inhibition of fibrogenic cytokine production, resulting in the suppression of collagen synthesis and deposition in the liver, though different mechanisms underlie their anti-fibrogenic effects.

Connective tissue growth factor and renal diseases: some answers, more questions

PURPOSE OF REVIEW

Connective tissue growth factor (CCN2) has recently received much attention as a possible key determinant of progressive renal fibrosis. However, the mechanism(s) by which this growth factor functions is not known. The purpose of this review is to summarize and discuss the recent findings regarding the possible mechanisms involved.

RECENT FINDINGS

Emerging evidence from in-vitro studies of renal cells indicates that connective tissue growth factor is a crucial mediator for transforming growth factor-beta-induced cellular dysfunction, manifest by increased cellular hypertrophy, synthesis of extracellular matrix proteins and their deposition and assembly around the cells. Indeed, recent evidence suggests that the interrelationship between connective tissue growth factor and transforming growth factor-beta is stronger than first thought. While transforming growth factor-beta induces the expression of connective tissue growth factor, the latter plays a key role in both bioactivation of latent transforming growth factor-beta and the promotion of its Smad signalling activity.

SUMMARY

Connective tissue growth factor is clearly implicated in the pathogenesis of progressive renal disease. Although there is much to learn about the production, function, and mechanism of action of connective tissue growth factor, some progress has been made in understanding the molecular basis of its relationship with transforming growth factor-beta. Elucidating the signal transduction pathways activated by connective tissue growth factor will also definitely help to clarify other actions of connective tissue growth factor which may be independent of transforming growth factor-beta. Because of the inflammatory and immunosuppressive properties of transforming growth factor-beta, connective tissue growth factor seems to be an attractive alternative therapeutic target for combating renal fibrosis.

Tyrosine phosphorylation of the LDL receptor-related protein (LRP) and activation of the ERK pathway are required for connective tissue growth factor to potentiate myofibroblast differentiation

Renal myofibroblasts play a crucial role in the accumulation of excess extracellular matrix during renal fibrosis. Both transforming growth factor-beta1 (TGFbeta1) and connective tissue growth factor (CTGF) are important profibrotic growth factors, which interact in the pathogenesis of fibrosis. In this study, we demonstrate that CTGF alone has no influence on myofibroblast transformation and fibronectin secretion in kidney interstitial fibroblasts, whereas incubation of CTGF in combination with TGFbeta1 enhanced TGFbeta1 responses, including myofibroblast activation, de novo expression of alpha-SMA, and extracellular accumulation of fibronectin. CTGF induced tryrosine phosphorylation of the cytoplasmic domain of the low-density lipoprotein receptor-associated protein (LRP) in fibroblasts, and the LRP-antagonist, receptor-associated protein (RAP) inhibited CTGF-induced tryrosine phosphorylation of LRP. Inhibition of LRP signaling reduced CTGF-mediated synergistic induction of alpha-SMA protein. Furthermore, the potentiating action of CTGF was neither dependent on modulation of TGFbeta1-induced Smad2 phosphorylation and its association with Smad4, nor did it result from nuclear accumulation of activated Smad2. When TGFbeta1-pretreated fibroblasts were incubated with CTGF, activation of ERK1/2 MAPK signaling was observed. Inhibition of ERK activation by the MEK1 inhibitor PD98059 was associated with a reduction of CTGF-promoted alpha-SMA protein expression. Our in vitro studies provide evidence that CTGF potentiates TGFbeta1-mediated myofibroblast differentiation and activates differentiated myofibroblasts.

Cell-type-specific activation of mitogen-activated protein kinases in PAN-induced progressive renal disease in rats

We examined the time-course activation and the cell-type specific role of MAP kinases in puromycin aminonucleoside (PAN)-induced renal disease. The maximal activation of c-Jun-NH2-terminal kinase (JNK), extracellular signal regulated kinase (ERK), and p38 MAP kinase was detected on Days 52, 38, and 38 after PAN-treatment, respectively. p-JNK was localized in mesangial and proximal tubular cells at the early renal injury. It was expressed, therefore, in the inflammatory cells of tubulointerstitial lesions. While, p-ERK was markedly increased in the glomerular regions and macrophages p-p38 was observed in glomerular endothelial cells, tubular cells, and some inflammatory cells. The results show that the activation of MAP kinases in the early renal injury by PAN-treatment involves cellular changes such as cell proliferation or apoptosis in renal native cells. The activation of MAP kinases in infiltrated inflammatory cells and fibrotic cells plays an important role in destructive events such as glomerulosclerosis and tubulointerstitial fibrosis.

Transforming growth factor-beta1, myofibroblasts, and tissue remodeling in the pathogenesis of tracheal injury: potential role of gastroesophageal reflux

Subglottic stenosis (SGS) is characterized by the obliteration of the tracheal lumen due to excessive deposition of connective tissue. We hypothesize that tracheal injury triggers the early production of transforming growth factor-beta1 (TGF-beta1), a factor implicated in fibroproliferative disorders. In turn, TGF-beta1 stimulates the transformation of tracheal fibroblasts into myofibroblasts with increased matrix production and scar contraction that might be influential in laying the foundation for the development of SGS. Consistent with this hypothesis, histologic analysis of tracheas from humans with SGS and from rats with experimental tracheal injury revealed increased alpha-smooth muscle actin-positive cells as compared to control tracheas, suggesting increased myofibroblast differentiation. Rat tracheal fibroblasts exposed to TGF-beta1 or gastric juice in vitro showed increased expression of alpha-smooth muscle actin, alterations in the expression of matrix molecules, and increased contraction of collagen gels. These findings suggest that gastric juice or other agents of tracheal injury promote tissue remodeling through the stimulation of the differentiation of fibroblasts into myofibroblasts.

Ac-SDKP reverses cardiac fibrosis in rats with renovascular hypertension

N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a natural substrate for the N-terminal active site of angiotensin-converting enzyme (ACE). We previously reported that Ac-SDKP prevented cardiac fibrosis in rats with renovascular or aldosterone-salt hypertension. However, it is not clear whether Ac-SDKP reverses cardiac fibrosis in hypertension, nor the mechanism(s) involved. In the present study, we tested the hypothesis that Ac-SDKP reversal of hypertension-induced cardiac fibrosis involves a decrease in transforming growth factor-beta (TGF-beta) and/or connective tissue growth factor (CTGF). In 2-kidney, 1-clip (2K-1C) hypertensive rats, Ac-SDKP at 400 or 800 microg/kg per day SC was started 8 weeks after hypertension and cardiac fibrosis were established and was continued for 8 weeks. Left ventricular (LV) collagen in rats with 2K-1C plus vehicle at 8 and 16 weeks after clipping was similar but higher than in the sham group (P<0.05). Ac-SDKP at 400 and 800 microg/kg per day, which increased plasma Ac-SDKP 2- and 5-fold, respectively, reversed the increase in LV collagen in a dose-dependent manner. The mechanism by which Ac-SDKP reverses LV fibrosis does not appear to depend on ACE inhibition by Ac-SDKP, since we found that Ac-SDKP at various doses did not affect blood pressure responses to exogenous angiotensin I or bradykinin. However, Ac-SDKP reversed the increase in LV TGF-beta and CTGF compared with rats with 2K-1C plus vehicle (P<0.005). We concluded that in hypertension, Ac-SDKP reverses cardiac fibrosis, perhaps due in part to a decrease in TGF-beta and CTGF in the heart.

Tissue transglutaminase and the progression of human renal scarring

Experimental renal scarring indicates that tissue transglutaminase (tTg) may be associated with the accumulation of extracellular matrix (ECM), both indirectly via TGF-beta1 activation and directly by the formation of epsilon(gamma-glutamyl) lysine dipeptide bonds within the ECM. The latter potentially accelerates deposition and confers the ECM with resistance to proteolytic digestion. Studied were 136 human renal biopsy samples from a range of chronic renal diseases (CRD) to determine changes in tTg and epsilon(gamma-glutamyl) lysine crosslinking. Immunofluorescence for insoluble tTg showed a 14-fold increase in the kidneys of CRD patients (5.3 +/- 0.5 versus 76 +/- 54 mV/cm(2)), which was shown to be active by a similar 11-fold increase in the epsilon(gamma-glutamyl) lysine crosslink (1.8 +/- 0.2 versus 19.3 +/- 14.2 mV/cm(2)). Correlations were obtained with renal function for tTg and crosslink. In situ hybridization for tTg mRNA showed that tubular epithelial cells were the major source of tTg; however, both mesangial and interstitial cells also contributed to elevated levels in CRD. This mRNA pattern was consistent with immunohistochemistry for soluble tTg. Changes in renal tTg and its product, the epsilon(gamma-glutamyl) lysine crosslink, occur in progressive renal scarring in humans independently of the original etiology and in a similar manner to experimental models. tTg may therefore play a role in the pathogenesis of renal scarring and fibrosis in patients with CRD and can therefore be considered a potential therapeutic target.

Fibrogenic stresses activate different mitogen-activated protein kinase pathways in renal epithelial, endothelial or fibroblast cell populations

Fibrogenic stresses promote progression of renal tubulointerstitial fibrosis, disparately affecting survival, proliferation and trans-differentiation of intrinsic renal cell populations through ill-defined biomolecular pathways. We investigated the effect of fibrogenic stresses on the activation of cell-specific mitogen-activated protein kinase (MAPK) in renal fibroblast, epithelial and endothelial cell populations. The relative outcomes (cell death, proliferation, trans-differentiation) associated with activation or inhibition of extracellular-regulated protein kinase (ERK) or stress activated/c-Jun N terminal kinase (JNK) were analysed in each renal cell population after challenge with oxidative stress (1 mmol/L H2O2), transforming growth factor-beta1 (TGF-beta1, 10 ng/mL) or tumour necrosis factor-alpha (TNF-alpha, 50 ng/mL) over 0-20 h. Apoptosis increased significantly in all cell types after oxidative stress (P < 0.05). In fibroblasts, oxidative stress caused the activation of ERK (pERK) but not JNK (pJNK). Inhibition of ERK by PD98059 supported its role in a fibroblast death pathway. In epithelial and endothelial cells, oxidative stress-induced apoptosis was preceded by early induction of pERK, but its inhibition did not support a pro-apoptotic role. Early ERK activity may be conducive to their survival or promote the trans-differentiation of epithelial cells. In epithelial and endothelial cells, oxidative stress induced pJNK acutely. Pretreatment with SP600125 (JNK inhibitor) verified its pro-apoptotic activity only in epithelial cells. Transforming growth factor-beta1 did not significantly alter mitosis or apoptosis in any of the cell types, nor did it alter MAPK activity. Tumor necrosis factor-alpha caused increased apoptosis with no associated change in MAPK activity. Our results demonstrate renal cell-specific differences in the activation of ERK and JNK following fibrotic insult, which may be useful for targeting excessive fibroblast proliferation in chronic fibrosis.

Urinary transforming growth factor-beta1 excretion in renal allograft recipients during the early post-transplantation period

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1), the major fibrogenic growth factor, is implicated in the pathogenesis of renal scarring in experimental and clinical nephropathies as well as in chronic allograft nephropathy. In this study we examined the pattern of changes of TGF-beta1 excretion in the urine and the sites of TGF-beta1 expression in the kidney of transplanted patients during the early post-transplantation period.

METHODS

Eighteen renal allograft recipients were included in the study. In all patients urinary TGF-beta1 levels were determined by ELISA in sequential measurements during the first two postoperative months and compared to that of 14 healthy subjects. The renal expression of TGF-beta1 protein was studied in 4 patients that underwent a biopsy of the transplanted kidney at the same period. All patients were treated with prednisolone, cyclosporin, and mycophenolate mofetil.

RESULTS

Urinary TGF-beta1 levels were increased during the first postoperative days. Although they were gradually reduced during the first two post-operative months, they remained significantly higher compared to those of normal subjects (580 +/- 148 ng/24 h vs. 310 +/- 140 ng/ 24 h p < 0.01). The decline of urinary TGF-beta1 excretion followed that of serum creatinine. TGF-beta1 protein expression was identified within the cytoplasm of tubular epithelial cells of transplanted patients.

CONCLUSIONS

Elevated urinary TGF-beta1 levels are observed during the early post-transplantation period in renal allograft recipients and are maintained high even after restoration of renal function to normal.

Urinary amino-terminal propeptide of type III procollagen (PIIINP) as a marker of interstitial fibrosis in renal transplant recipients

BACKGROUND

Interstitial fibrosis in the protocol biopsy specimens of transplanted kidneys is regarded as the most reliable predictor of future impaired renal function. Type I and III collagens are the main components of renal fibrosis. During the synthesis and deposition of type III collagen, an amino-terminal propeptide (PIIINP) of a molecular weight of 44 kDa is degraded from the collagen and secreted into surroundings. Increased circulating PIIINP has been shown to reflect ongoing fibrotic processes.

METHODS

The extent of interstitial fibrosis in 6-month protocol biopsy specimens was recorded, and the urinary excretion of PIIINP in 24-hr urine specimens was measured in 79 graft patients. We also measured the urinary excretion of transforming growth factor (TGF)-beta 1, alpha(1)-microglobulin (alpha(1)M), and albumin and recorded the changes in creatinine clearance during 0.5 to 6 (mean, 4.3) posttransplant follow-up years.

RESULTS

The urinary excretion of PIIINP was significantly lower in patients with no interstitial fibrosis compared with patients with mild or moderate interstitial fibrosis (P<0.01). The urinary PIIINP-to-creatinine ratio correlated closely with the extent of interstitial fibrosis (r=0.410, P<0.001), with TGF-beta 1-to-creatinine (r=0.585, P<0.001) and alpha(1)M-to-creatinine (r=0.438, P<0.001) but not with the albumin-to-creatinine ratio. There was a close correlation between urinary TGF-beta 1 and alpha(1)M (r=0.508, P<0.001), whereas no correlation was found between urinary and serum PIIINP or between urinary PIIINP-to-creatinine ratio and glomerular filtration rate (GFR). During the follow-up, the GFR decreased in 42% of patients with a PIIINP-to-creatinine ratio over 100 ng/mmol, but only in 8% of patients with a ratio less than 100 ng/mmol (P<0.01).

CONCLUSIONS

These findings show that the urinary PIIINP-to-creatinine ratio reflects the ongoing fibrotic processes in the kidney. Tubular epithelial cell injury may initiate the fibrotic processes, and elevated concentrations of urinary TGF-beta 1 and alpha(1)M may associate with the increased production and deposition of collagen type III in the graft. We conclude that measurements of urinary excretion of PIIINP can be used as an early noninvasive indicator of renal fibrosis after kidney transplantation.

Monocytes may promote myofibroblast accumulation and apoptosis in Alport renal fibrosis

BACKGROUND

In interstitial fibrosis, monocytes and myofibroblasts have been directly implicated in scarring, apoptosis, and tissue necrosis. While much has been done to explore the role of these cell types individually in fibrosis, the interactive dependency of monocytes and myofibroblasts has been only marginally explored.

METHODS

Alport mice were treated or not with a soluble receptor inhibitor for transforming growth factor-beta 1 (TGF-beta 1), which was previously shown to inhibit the accumulation of myofibroblasts, but not monocytes, in the tubulointerstitium. Kidneys were examined for fibrosis using several matrix markers, TGF-beta 1 mRNA expression by in situ hybridization, apoptosis using the terminal deoxynucleotidyl transferase-mediated uridine triphosphate nick end labeling (TUNEL) assay, expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPS) by dual immunofluorescence microscopy, MMP activity by gelatin and in situ zymography, MMP mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR), and basement membrane degradation by dual immunofluorescence confocal microscopy and electron microscopy.

RESULTS

Treated mice showed a markedly reduced accumulation of matrix proteins. Tissue monocytes express TGF-beta 1 mRNA, and TGF-beta 1 is required for myofibroblast accumulation. The number of apoptotic cells was not influenced by TGF-beta 1 inhibition. Monocytes express MMP-2, MMP-9, TIMP-2, and TIMP-3. MMP activity and mRNA expression is equally up regulated in treated and untreated Alport mice. Tubular basement membranes (TBM) around clusters of monocytes are notably degraded. TGF-beta 1 inhibition does not extend the life of Alport mice.

CONCLUSION

These studies demonstrate that monocytes may influence myofibroblast accumulation via TGF-beta1, and that monocytes, and not myofibroblasts, are associated with tubular atrophy in Alport mice. Elevated MMP expression and activity is associated with TBM destruction near monocytes clusters, suggesting an anoikis mechanism may contribute to apoptosis in this model.

Transforming growth factor-beta signal transduction and progressive renal disease

Transforming growth factor-beta (TGF-beta) superfamily members are multifunctional growth factors that play pivotal roles in development and tissue homeostasis. Recent studies have underscored the importance of TGF-beta in regulation of cell proliferation and extracellular matrix synthesis and deposition. TGF-beta signaling is initiated by ligand binding to a membrane-associated receptor complex that has serine/threonine kinase activity. This receptor complex phosphorylates specific Smad proteins, which then transduce the ligand-activated signal to the nucleus. Smad complexes regulate target gene transcription either by directly binding DNA sequences, or by complexing with other transcription factors or co-activators. There is extensive crosstalk between the TGF-beta signaling pathway and other signaling systems, including the mitogen-activated protein kinase pathways. The importance of TGF-beta in regulation of cell growth has been emphasized by recent observations that mutations of critical elements of the TGF-beta signaling system are associated with tumor progression in patients with many different types of epithelial neoplasms. TGF-beta has emerged as a predominant mediator of extracellular matrix production and deposition in progressive renal disease and in other forms of chronic tissue injury. In this overview, recent advances in our understanding of TGF-beta signaling, cell cycle regulation by TGF-beta, and the role of TGF-beta in progressive renal injury are highlighted.

Apoptosis and myofibroblast expression in human glomerular disease: a possible link with transforming growth factor-beta-1

BACKGROUND/AIMS

The pathophysiological pathways involved in the pathogenesis and evolution of renal fibrosis, have not been fully elucidated. Transforming growth factor-beta(1) (TGF-beta(1)) is involved in the development of renal scarring. Apoptosis is responsible for intrinsic cell deletion observed in end-stage kidney disease. Myofibroblasts are involved in the development of renal fibrosis. This study investigates whether there is a potential relationship between apoptosis, myofibroblast infiltration and TGF-beta(1) expression in the kidney of patients with glomerulonephritis (GN).

METHODS

Forty patients with various types of GN were included in the study. Myofibroblasts and TGF-beta(1) positive cells were detected in kidney biopsies by immunohistochemistry, while apoptotic cells were detected by the in situ end labelling of fragmented DNA.

RESULTS

Myofibroblasts were identified in the glomeruli of some patients with severe mesangioproliferative GN and glomerulosclerosis but a more intensive myofibroblast expression was found in the renal interstitium. TGF-beta(1) was expressed in the cytoplasm of tubular epithelial cells, in the renal interstitium and in the glomeruli of patients with GN. Apoptotic cells were mainly detected in the tubules and interstitium and were present in areas with intense myofibroblast infiltration. Positive correlations were observed between the intensity of myofibroblast expression in the interstitium and apoptosis in the tubulointerstitial area (r = 0.521, p < 0.01) as well as TGF-beta(1) expression (r = 0.462, p < 0.05) and degree of renal impairment (r = 0.430, p < 0.05).

CONCLUSIONS

These observations suggest that myofibroblast infiltration and apoptosis along with TGF-beta(1) expression are associated with the development of interstitial fibrosis in patients with glomerular disease.

Connective tissue growth factor: an attractive therapeutic target in fibrotic renal disease

Despite diverse initiating insults, glomerulosclerosis and tubulointerstitial fibrosis are pathological features common to most forms of progressive renal disease. Control of systemic hypertension and blockade of the renin-angiotensin system ameliorate the rate of progression of chronic renal disease; however they generally fail to completely arrest the scarring process. While the chain of events leading to scarring are still being defined, TGF-beta is a cytokine that plays a pivotal role in the pathogenesis of glomerulosclerosis and tubulointerstitial fibrosis [1]. Given the pleiotropic effects of TGF-beta, significant attention has focused on the potential of its downstream mediators as therapeutic targets. Connective tissue growth factor (CTGF) is a member of the CCN gene family, which includes CyR61 (cysteine rich 61), Nov (Nephroblastoma overexpressed) and the WISP family (for review see [2,3,4]). These immediate-early genes coordinate complex biologic processes during differentiation and tissue repair [5]. Increased expression of CTGF has been detected in experimental and human renal fibrosis where it correlates with glomerulosclerosis and the degree of tubulointerstitial fibrosis [6]. In these settings CTGF expression is regulated at least in part by TGF-beta. This review details the biology of CTGF with specific reference to its potential as a therapeutic target in renal fibrosis.