HSP47 regulates ECM accumulation in renal proximal tubular cells induced by TGF-ß1 through ERK1/2 and JNK MAPK pathways.

Heat shock protein (HSP)47 is a collagen-specific molecular chaperone that is essential for the biosynthesis of collagen molecules. It is likely that increased levels of HSP47 contribute to the assembly of procollagen and thereby cause an excessive accumulation of collagens in disease processes associated with fibrosis. Although HSP47 promotes renal fibrosis, the underlying mechanism and associated signaling events have not been clearly delineated. We examined the role of HSP47 in renal fibrosis using a rat unilateral ureteral obstruction model and transforming growth factor (TGF)-ß(1)-treated human proximal tubular epithelial (HK-2) cells. An upregulation of HSP47 in both in vivo and in vitro models was observed, which correlated with the increased synthesis of extracellular matrix (ECM) proteins and expression of tissue-type plasminogen activator inhibitor (PAI)-1. Blockade of HSP47 by short interfering RNA suppressed the expression of ECM proteins and PAI-1. In addition, TGF-ß(1)-induced HSP47 expression in HK-2 cells was attenuated by ERK1/2 and JNK MAPK inhibitors. These data suggest that ERK1/2 and JNK signaling events are involved in modulating the expression of HSP47, the chaperoning effect of which on TGF-ß(1) would ultimately contribute to renal fibrosis by enhancing the synthesis and deposition of ECM proteins.

Norcantharidin inhibits the expression of extracellular matrix and TGF-ß1 in HK-2 cells induced by high glucose independent of calcineurin signal pathway.

Norcantharidin (NCTD) was shown in our previous studies to attenuate renal tubulointerstitial fibrosis in rat models with diabetic nephropathy (DN). The aim of this study was to determine the effects of NCTD on the expression of extracellular matrix (ECM) and TGF-ß1 in HK-2 cells stimulated by high glucose and on calcineurin (CaN)/NFAT pathway. Whether or not the antifibrotic effect of NCTD on renal interstitium was dependent on its inhibition of CaN pathway was also investigated. Experimental concentrations of NCTD were verified by cytotoxic test and MTT assay. HK-2 cells were transfected with CaN small interference RNA (siRNA). The mRNA and protein expressions of FN, ColIV, TGF-ß1, and CaN in HK-2 cells were detected by real-time PCR and western blot. The CaN/NFAT pathway was examined by indirect immunofluorescence and western blot. Our study revealed that NCTD concentrations over 5 mg/l had overt cytotoxicity on HK-2 cells. Meanwhile, both 2.5 and 5 mg/l NCTD inhibited HK-2 cell proliferation (P < 0.05). NCTD inhibited the upregulation of FN, ColIV, and TGF-ß1 of HK-2 cells stimulated by high glucose (P < 0.05), and also significantly downregulated the expression of CaN mRNA and protein in HK-2 cells (P < 0.05). In addition, not only was the nuclear translocation of NFATc inhibited, but its protein level in the nucleus was also reduced. Following CaN siRNA transfection, CaN mRNA and protein expression were significantly decreased. In contrast, the protein levels of FN, ColIV, and TGF-ß1 increased in HK-2 cells stimulated by high glucose (P < 0.05). However, NCTD treatment downregulated their expression. These results indicated that NCTD could decrease the expression of ECM and TGF-ß1 in HK-2 cells stimulated by high glucose, downregulate CaN expression, and block the CaN/NFAT signaling pathway. However, the effect of NCTD on inhibition of the expression of ECM and TGF-ß1 was not associated with its inhibition of the CaN/NFAT pathway.

Norcantharidin attenuates tubulointerstitial fibrosis in rat models with diabetic nephropathy.

OBJECTIVE: To investigate the effects of norcantharidin (NCTD) on tubulointerstitial fibrosis of diabetic nephropathy (DN) in streptozotocin-induced rat model. METHODS: Sprague-Dawley rats were randomly divided into control group, model group, low-dose NCTD (0.05 mg/kg/day) group, and high-dose NCTD (0.1 mg/kg/day) group. The model group was induced by injection intraperitoneally with 30 mg/kg streptozotocin in 0.1 mol/L sodium citrate solution (pH 4.5), after high-calorie foods were given for 2 months. NCTD was administered daily after the DN rat model was built. Rats were sacrificed at the end of the third and the eighth week; renal fibrosis and the expression of FN, collagen IV, TGF-ß1, and calcineurin (CaN) were detected by Masson and immunohistochemistry staining, respectively. RESULTS: Tubulointerstitial fibrosis was observed in DN rats, this kind of pathological changes was ameliorated in NCTD treatment group (p < 0.05). The expressions of FN, collagen IV, and TGF-ß1 protein increased in the tubulointerstitial field of DN rats compared with the rats in control group. NCTD treatment could dose-dependently decrease their expression and reverse the fibrotic degree (p < 0.05). Meanwhile, the expression of CaN was detected in tubular fields of normal kidney and increased in the tubulointerstitial field in DN rats. However, NCTD downregulated its expression in a dose-dependent manner (p < 0.05). CONCLUSIONS: NCTD could downregulate FN, collagen IV, and TGF-ß1 expression in tubulointerstitial fields and attenuate tubulointerstitial fibrosis in the early stage of DN rats. NCTD also alleviated the expression of CaN in tubules in DN. The relationship between the role of NCTD's anti-tubulointerstitial fibrosis and its inhibition to CaN expression remains to be further elucidated.

p66Shc mediates high-glucose and angiotensin II-induced oxidative stress renal tubular injury via mitochondrial-dependent apoptotic pathway.

p66Shc, a promoter of apoptosis, modulates oxidative stress response and cellular survival, but its role in the progression of diabetic nephropathy is relatively unknown. In this study, mechanisms by which p66Shc modulates high-glucose (HG)- or angiotensin (ANG) II-induced mitochondrial dysfunction were investigated in renal proximal tubular cells (HK-2 cells). Expression of p66Shc and its phosphorylated form (p-p66Shc, serine residue 36) and apoptosis were notably increased in renal tubules of diabetic mice, suggesting an increased reactive oxygen species production. In vitro, HG and ANG II led to an increased expression of total and p-p66Shc in HK-2 cells. These changes were accompanied with increased production of mitochondrial H(2)O(2), reduced mitochondrial membrane potential, increased translocation of mitochondrial cytochrome c from mitochondria into cytosol, upregulation of the expression of caspase-9, and ultimately reduced cell survival. Overexpression of a dominant-negative Ser36 mutant p66Shc (p66ShcS36A) or treatment of p66Shc- or PKC-ß-short interfering RNAs partially reversed these changes. Treatment of HK-2 cells with HG and ANG II also increased the protein-protein association between p-p66Shc and Pin1, an isomerase, in the cytosol, and with cytochrome c in the mitochondria. These interactions were partially disrupted with the treatment of PKC-ß inhibitor or Pin1-short interfering RNA. These data suggest that p66Shc mediates HG- and ANG II-induced mitochondrial dysfunctions via PKC-ß and Pin1-dependent pathways in renal tubular cells.

Anti-cyclic citrullinated peptide antibody predicts the development of rheumatoid arthritis in patients with undifferentiated arthritis.

BACKGROUND: Clinical outcomes of undifferentiated arthritis (UA) are diverse, and only 40% of patients with UA develop rheumatoid arthritis (RA) after 3 years. Discovering predictive markers at disease onset for further intervention is critical. Therefore, our objective was to analyze the clinical outcomes of UA and ascertain the predictors for RA development. METHODS: We performed a prospective, multi-center study from January 2013 to October 2016 among Chinese patients diagnosed with UA in 22 tertiary-care hospitals. Clinical and serological parameters were obtained at recruitment. Follow-up was undertaken in all patients every 12 weeks for 2 years. Predictive factors of disease progression were identified using multivariate Cox proportional hazards regression. RESULTS: A total of 234 patients were recruited in this study, and 17 (7.3%) patients failed to follow up during the study. Among the 217 patients who completed the study, 83 (38.2%) patients went into remission. UA patients who developed RA had a higher rheumatoid factor (RF)-positivity (42.9% vs. 16.8%, χ = 8.228, P = 0.008), anti-cyclic citrullinated peptide (CCP) antibody-positivity (66.7% vs. 10.7%, χ = 43.897, P < 0.001), and double-positivity rate of RF and anti-CCP antibody (38.1% vs. 4.1%, χ = 32.131, P < 0.001) than those who did not. Anti-CCP antibody but not RF was an independent predictor for RA development (hazard ratio 18.017, 95% confidence interval: 5.803-55.938; P < 0.001). CONCLUSION: As an independent predictor of RA, anti-CCP antibody should be tested at disease onset in all patients with UA.

Norcantharidin ameliorates proteinuria, associated tubulointerstitial inflammation and fibrosis in protein overload nephropathy.

Norcantharidin (NCTD), the demethylated analog of cantharidin isolated from Mylabris, is an anticancer drug routinely used against various human cancers in China. The aims of this study are to learn if NCTD has a protective action against severe proteinuria and consequent interstitial inflammation and fibrosis, and if the inhibition of nuclear factor-kappaB (NF-kappaB) and connective tissue growth factor (CTGF) by NCTD might be involved. Male Sprague-Dawley rats with protein overload nephropathy induced by intraperitoneally injected bovine serum albumin were used as a model. The histopathological examination of kidney tissue in the 9th week by light microscopy and scanning electron microscopy revealed that inflammatory cells had extensively infiltrated into the tubulointerstitial areas with interstitial fibrosis. The administration of NCTD at 0.1 mg/kg/day to the bovine-serum-albumin-injected animal models effectively reduced the proteinuria, and prevented the proteinuria-induced interstitial inflammation and fibrosis. Expressions of the NF-kappaB p65 subunit and CTGF, detected by immunohistochemistry, Western blotting and reverse-transcription polymerase chain reaction, were upregulated in protein overload nephropathy and were attenuated by NCTD. Inhibition of the expressions of the NF-kappaB p65 subunit and CTGF was one beneficial effect of NCTD. These results suggest that in addition to the antiproteinuric action of NCTD, due to its anti-inflammatory and antifibrotic effects as shown in the present study, it may become a therapeutic agent for proteinuria and its associated chronic inflammatory and fibrotic nephropathy.

Smad Anchor for Receptor Activation Regulates High Glucose-Induced EMT via Modulation of Smad2 and Smad3 Activities in Renal Tubular Epithelial Cells.

BACKGROUND: SARA is an essential adaptor protein in TGF-ß1 signaling and it is also involved in the process of Epithelial-mesenchymal transition (EMT) and fibrosis. Our aim was to investigate the effect of SARA on high glucose (HG)-induced EMT and extracellular matrix (ECM) synthesis in renal tubular epithelial cells. METHODS: The cells were transfected with the following plasmids: wild-type SARA (SARA-WT), SARA-dSBD (SARA with Smad binding domain deletion) and then subjected to HG ambience (30 mM). The expression levels were assessed by Western-blot, real-time PCR and immunofluorescence. RESULTS: HG-induced EMT phenotype with increased expression of ECM protein in HK-2 cells. This was associated with the decreased expression of SARA and Smad2. In comparison with the HG group, overexpression of SARA in HK-2 cells, a relatively high upregulation of ZO-1 expression was seen, while that of Vimentin, fibronectin and collagen I was decreased. The Smad2 protein expression was increased in HK-2 cells after transfection with SARA (WT) plasmid. Interestingly, the overexpression of SARA prolonged the activity period of Smad2 and shortened that of Smad3, which seemed consistent with the change of EMT phenotype and ECM changes in HK-2 cell induced by HG. CONCLUSIONS: SARA regulates HG-induced EMT and ECM excretion via modulation of the activation of Smad2 and Smad3 in renal tubular epithelial cells. In view of these findings, it is conceivable that SARA may serve as a potential novel target in pre-EMT states for the amelioration renal fibrosis seen in chronic kidney diseases.

[Depression of mPges expression by troglitazone in human renal glomerulus induced by high glucose and LPS].

OBJECTIVE: To determine the influence of troglitanzone on the expression of mPGEs induced by high glucose or LPS in human glomeruli cultured in vitro. METHODS: Human glomeruli were isolated and incubated by LPS or high glucose absence or presence with different concentrations of troglitazone. The concentration of mPGEs in the supernatant was measured by an enzyme-linked immunosorbent assay (ELISA). RESULTS: LPS (10 microg/ml) and 5% glucose could improve the concentration of mPGEs significantly in the supernatant by cultured human glomeruli, and troglitazone (10 - 20 nmol/L) could block its increase (P < 0.05). CONCLUSION: High glucose and LPS can improve mPGEs expression in cultured human glomeruli, and troglitazone can block this effects. These data suggest that PPAR-gamma agonist troglitanzone may be relevant to the treatment of diabetic nephropathy and inflammation in glomerluli.

Pharmacogenomics of biological treatment in rheumatoid arthritis.

INTRODUCTION: Rheumatoid arthritis (RA) demonstrates a high heterogeneity in clinical responses to treatment. Although the efficacy of biological therapy has undoubtedly been established, the response differs considerably between individuals. This variability between individuals has aroused the research for biomarkers predictive of treatment response. Pharmacogenomics underlying individual responses to drugs is rapidly developed and has the potential of realizing the personalized therapy in RA. This review will summarize the pharmacogenomics of biological therapies approved for clinical RA treatment. AREAS COVERED: The pharmacogenomics underlies individual responses to biological drugs in RA. Current studies on pharmacogenomics of biological therapy in RA are presented. EXPERT OPINION: The personalized treatment in RA according to pharmacogenomics is promising, but the available pharmacogenomic data on biological treatment in RA are not adequate and consistent and still require further larger sample studies to corroborate.

Smad anchor for receptor activation (SARA) in TGF-beta signaling.

Smad anchor for receptor activation (SARA) is known as Smad cofactor that interacts directly with Smad2/3 and functions to recruit Smad2/3 to the TGF-beta receptor. SARA plays an essential role in TGF-beta-induced Smad2 activation and it may modulate TGF-beta signaling through regulating the balance between Smad2 and Smad3. SARA also functions as an anchor for catalytic subunit of protein phosphatase 1 (PP1c) and maybe involved in the dephosphorylation of TGF-beta type I receptor (TbetaR-I) mediated by Smad7. The expression of SARA changes as the development of epithelial to mesenchymal transition (EMT) and fibrosis and it plays a critical role in the maintenance of epithelial cell phenotype. Modulation of SARA may provide a new therapeutic approach to TGF-beta-mediated EMT and fibrosis.

Maltose, a promising osmotic agent in peritoneal dialysis solution.

Peritoneal dialysis has undergone considerable development from a technological point of view, and osmotic agent has played the essential role in peritoneal dialysis fluid. Because the most commonly used osmotic agent is glucose and icodextrin, there are some disadvantages related to the use of glucose-based solutions and icodextrin. So it is urgent to develop a new peritoneal dialysis osmotic agent. According to these characteristics of glucose and icodextrin, it is promising to explore a better osmotic agent of peritoneal dialysis solution which is able to allow maintenance of the maximum ultrafiltration gradient, and prevent toxicity or accumulation of unwanted substances in the blood, being non-toxic or less-toxic, furthermore the metabolite should not cause significant metabolic disturbance. Maltose may be one of promising osmotic agent and may put an important influence on development of peritoneal dialysis.