High salt aggravates renal inflammation via promoting pro-inflammatory macrophage in 5/6-nephrectomized rat.

The increasing incident of chronic kidney disease (CKD) in recent years might be related to a change in dietary habits, known as excessive salt intake. Given excessive salt promotes pathogenic T cells responses. Since the importance of macrophage in the development of CKD, we addressed the effect of high salt loading on in a rat CKD model. We observed that 5/6Nx rats receiving a high salt diet showed strongly enhanced macrophage infiltration and activation in the renal tissue accompanied by deteriorated renal inflammation. Then we used the microarray expression profiling to detect the effect of additional Nacl on peritoneal macrophage derived from 5/6Nx. The NaCl treatment of macrophage extracted from 5/6Nx rat elicited a strong pro-inflammatory phenotype characterized by enhanced proinflammatory cytokine production, increased expression of molecules mainly involved in immune response process. This NaCl-induced pro-inflammatory macrophage phenotype was accompanied by increased phosphorylation of STAT1. Taken together, our study demonstrated that high salt intake promotes immune activation of macrophages through the STAT1 independently and exacerbates the kidney accompanied by promotion of inflammation. Thus, changes in diet may provide a novel strategy for the prevention or amelioration of CKD.

[Analysis of pregnancy outcomes in 66 patients with systemic lupus erythematosus].

OBJECTIVE: To analyze the outcomes of pregnancies in women with systemic lupus erythematosus (SLE) and the risk factors affecting the outcomes. METHODS: The data of SLE patients with pregnancy admitted from October, 2006 and September, 2015 were analyzed for assessing the maternal and fetal outcomes and complications. Their risk factors affecting the outcomes of the pregnancies were analyzed. RESULTS: The 66 SLE patients (69 pregnancies) had a mean age at SLE diagnosis of 22.9 ∓ 5.1 years with a mean duration of SLE of 4.1∓3.6 years before pregnancy. Forty-five (65.2%) of the patients received oral medication for SLE treatment during pregnancy, and 44 (63.8%) were treated with prednisone and 19 (27.5%) were treated with hydroxychloroquine. The highest SLEDAI score was 6.8∓7.4 during pregnancy. The patients with moderate-to-severe disease activity had a higher rate of fetal loss (12 [54.5%] vs 12 [25.5%]) with a significantly lower birth weight of the newborns than those with remittent or mild disease (2073.0∓ 778.7 vs 2817.8∓533.7 g, P<0.05). The patients with moderate-to-severe disease activity also had higher rates of new-onset SLE (9 [40.9%] vs 6 [12.8%]), hypertension (12 [54.5%] vs 3 [6.4%]), active lupus nephritis (22 [100%] vs 4 [8.5%]), pneumonia (5 [22.7%] vs 2 [4.3%]), and renal insufficiency (8 [36.4%] vs 2 [4.3%]) compared with patients with remittent and mild disease (P<0.05). Active lupus nephritis (OR=6.10,95%CI: 1.43-25.96) was a significant predictor of adverse outcomes of the pregnancies. CONCLUSION: Fetal loss and maternal complications are common in patients with SLE in relation with the disease activity. Active lupus nephritis is a predictor for poor outcomes of pregnancies in SLE patients.

[Assessment of renal function and risk factors for renal impairment in patients with hepatitis B virus-related liver cirrhosis].

OBJECTIVE: To evaluate the renal function in treatment-naive patients with hepatitis B virus (HBV) related cirrhosis and to identify the risk factors for renal impairment. METHODS: We collected the data of 860 HBV-related cirrhosis patients hospitalized in our unit between Jan 1, 2011 and Dec 31, 2011. Liver function of the patients was assessed with Child-Pugh score system, and the renal function with estimated glomerular filtration rate (eGFR) calculated by Modification of Diet in Renal Disease (MDRD) equation recommended by Kidney Disease Outcomes Quality Initiative (K/DOQI). We investigated the prevalence of renal impairment (eGFR>60 ml/min/1.73 m(2)) among these patients and explored the risk factors for renal impairment. RESULTS: Of the 860 patients, 296 had complete clinical data and were included in our analysis. The overall incidence of renal impairment among the enrolled patients was 8.45% (25/296). Patients with Child-Pugh stage C showed a significantly higher incidence of renal impairment than those with stages B and A (17.17% [17/99] vs 6.67%[7/105] vs 1.09% [1/92], P<0.001). Age, history of hyperuricemia, and Child-Pugh score were identified as the risk factors for renal impairment in these patients. CONCLUSION: In patients with HBV-related liver cirrhosis, the incidence of renal impairment increases significantly with deterioration of the liver function, and renal function should be regularly monitored in these patients for appropriate antiviral treatment.

The effect of inhibition of endoplasmic reticulum stress on lipolysis in white adipose tissue in a rat model of chronic kidney disease.

AIM: Lipolysis in fat tissue plays an important role in the development of metabolic disturbances, a characteristic feature of chronic kidney disease (CKD). In the present study, we tested the hypothesis that the inhibition of endoplasmic reticulum (ER) stress could alleviate lipolysis in white adipose tissue in a rat model of CKD. METHODS: A rat model of CKD was established by a method of reduced renal mass (RRM). Lipolysis was measured as the release of glycerol in ex vivo fat pads and cultured primary adipocytes. The activity of lipases and markers of ER stress were measured by Western blotting and immunoprecipitation. RESULTS: Our data showed that lipolysis in visceral white adipose tissue was increased in RRM rats compared with control rats. In addition, increased phosphorylation of hormone-sensitive lipase (HSL) and binding of adipose triglyceride lipase (ATGL) to comparative gene identification-58 (CGI-58) protein were observed in the RRM rats. The phosphorylation of ER stress markers, including IRE1α, PERK, and eukaryotic initiation factor (eIF) 2α, and the expression of ER stress marker 78 kDa glucose-regulated protein (GRP78) were significantly increased in RRM rats. Treatment with an inhibitor of ER stress partially but significantly alleviated lipolysis, and this alleviation was accompanied by reduced binding of ATGL to CGI-58. CONCLUSION: Our results showed that enhanced lipolysis and ER stress occurred in visceral white adipose tissue in a rat model of CKD. Moreover, inhibition of ER stress significantly alleviated lipolysis. These findings suggest that ER stress is a potential therapeutic target for the metabolic disturbances associated with CKD.

Current pattern of Chinese dialysis units: a cohort study in a representative sample of units.

BACKGROUND: Understanding the characteristics of Chinese dialysis patients and the current practice trends is the first step to evaluate the association between practice pattern and outcome in these populations. In the present study, we evaluated the status of medical treatment and characteristic features of chronic dialysis patients in China. METHODS: Through a clustering sampling, we selected 9 centers from the largest dialysis facilities in 6 cities around China. All adult undergoing dialysis in the selected units were screened. A total of 2388 (1775 on hemodialysis (HD) and 613 on peritoneal dialysis (PD)) patients were finally enrolled. All data were collected at enrollment on the bases of review of medical records. RESULTS: In this cohort, 1313 (55.0%) were male. The mean age was 54 years old. The median time for dialysis was 26 months (12 - 51 months). Seventy-five percent of patients were on HD and 25.0% on PD. Among PD patients, about 21% patients did not receive dialysis adequacy. For HD patients, about 14.0% of them did not achieve dialysis adequacy when the target of kt/V was set as 1.2. Only 44.7% of patients achieved blood pressure target of 140/90 mmHg. About 60% of patients did not reach the hemoglobin target of 110 g/L even though 85.0% of them were treated with erythropoietin. In addition, 48.5% of the patients had uncontrolled mineral metabolism revealed by the high calcium-phosphate product. Compared with HD patients, higher level of serum glucose, triglyceride, and total and low density lipoprotein cholesterol were more common in PD patients. CONCLUSIONS: This observational study suggests that many Chinese dialysis patients did not achieve the therapeutic target, particularly in blood pressure control, anemia correction, and mineral balance. PD patients were more likely to suffer metabolic disturbance.

China collaborative study on dialysis: a multi-centers cohort study on cardiovascular diseases in patients on maintenance dialysis.

BACKGROUND: Cardiovascular disease (CVD) is the main cause of death in patients on chronic dialysis. The question whether dialysis modality impacts cardiovascular risk remains to be addressed. China Collaborative Study on Dialysis, a multi-centers cohort study, was performed to evaluate cardiovascular morbidity during maintenance hemodialysis (HD) and peritoneal dialysis (PD). METHOD: The cohort consisted of chronic dialysis patients from the database of 9 of the largest dialysis facilities around China. The inclusion period was between January 1, 2005, and December 1, 2010. Cardiovascular morbidity was defined as the presence of clinically diagnosed ischemic heart disease, heart failure, peripheral vascular disease, and/or stroke. The patients who had cardiovascular morbidity before initiation of dialysis were excluded. Data collection was based on review of medical record. RESULT: A total of 2,388 adult patients (1,775 on HD and 613 on PD) were enrolled. Cardiovascular morbidity affected 57% patients and was comparable between HD and PD patients. However, clinically diagnosed ischemic heart disease and stroke was more prevalent in PD than HD patients. When the patients were stratified by age or dialysis vintage, the cardiovascular morbidity was significantly higher in PD than HD among those aged 50 years or older, or those receiving dialysis over 36 months. Multivariate analysis revealed that the risk factors for cardiovascular morbidity had different pattern in PD and HD patients. Hyperglycemia was the strongest risk factor for cardiovascular morbidity in PD, but not in HD patients. Hypertriglyceridemia and hypoalbuminemia were independently associated with CVD only in PD patients. CONCLUSIONS: Cardiovascular morbidity during chronic dialysis was more prevalent in PD than HD patients among those with old age and long-term dialysis. Metabolic disturbance-related risk factors were independently associated with CVD only in PD patients. Better understanding the impact of dialysis modality on CVD would be an important step for prevention and treatment.

Changes in pathological pattern and treatment regimens based on repeat renal biopsy in lupus nephritis.

BACKGROUND: Relapses occur frequently in patients with lupus nephritis. Renal biopsy is the gold standard for assessing renal activity and hence guiding the treatment. Whether repeat renal biopsy is helpful during flares of lupus nephritis remains inconclusive. In the present study, we retrospectively reviewed the patients with lupus nephritis who had more than one renal biopsy with the hope to find the clinical value of repeat biopsy. METHODS: Patients who had a diagnosis of lupus nephritis and two or more renal biopsies were selected from the database of the patient pathology registration at this renal division. Renal biopsy was evaluated according to the International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification of lupus nephritis. The pathological patterns and treatment regimens were analyzed after a repeat biopsy. RESULTS: We identified 44 systemic lupus erythematosus patients with serial renal biopsies. In total, there were 94 renal biopsies. Overall, the pathological transition occurred in 64% instances according to the ISN/RPS class. When the transition was analyzed according to proliferative, membranous or mix lesions, it showed different profile: 35% in patients with proliferative lesion, 23.5% patients with mix lesions, 100% in patients with pure membranous lesion. The pathological transition could not be predicted by any clinical characteristics. After the repeat renal biopsy, 34% of patients had a change in their treatment regimens. CONCLUSIONS: The pathological conversion was very prevalent in patients with lupus nephritis. However, the transitions became less prevalent when they were analyzed according to pure membranous, proliferative, and mix lesion. Repeat biopsy might be helpful to avoid unnecessary increased immunosuppression therapy.

Acute and acute-on-chronic kidney injury of patients with decompensated heart failure: impact on outcomes.

BACKGROUND: Acute worsening of renal function, an independent risk factor for adverse outcomes in acute decompensated heart failure (ADHF), occurs as a consequence of new onset kidney injury (AKI) or acute deterioration of pre-existed chronic kidney disease (CKD) (acute-on-chronic kidney injury, ACKI). However, the possible difference in prognostic implication between AKI and ACKI has not been well established. METHODS: We studied all consecutive patients hospitalized with ADHF from 2003 through 2010 in Nanfang Hospital. We classified patients as with or without pre-existed CKD based on the mean estimated glomerular filtration rate (eGFR) over a six-month period before hospitalization. AKI and ACKI were defined by RIFLE criteria according to the increase of the index serum creatinine. RESULTS: A total of 1,005 patients were enrolled. The incidence of ACKI was higher than that of AKI. The proportion of patients with diuretic resistance was higher among patients with pre-existed CKD than among those without CKD (16.9% vs. 9.9%, P = 0.002). Compared with AKI, ACKI was associated with higher risk for in-hospital mortality, long hospital stay, and failure in renal function recovery. Pre-existed CKD and development of acute worsening of renal function during hospitalization were the independent risk factors for in-hospital death after adjustment by the other risk factors. The RIFLE classification predicted all-cause and cardiac mortality in both AKI and ACKI. CONCLUSIONS: Patients with ACKI were at greatest risk of adverse short-term outcomes in ADHF. Monitoring eGFR and identifying CKD should not be ignored in patients with cardiovascular disease.

Accumulation of circulating advanced oxidation protein products is an independent risk factor for ischaemic heart disease in maintenance haemodialysis patients.

AIM: Whether the burden of advanced oxidation protein products (AOPP) accumulation, a marker of oxidative stress, is affected by dialysis modality remains unclear. We compared the serum levels of AOPP in patients on haemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) and tested the hypothesis that an accumulation of AOPP was an independent risk factor for cardiovascular disease. METHODS: This was a cross-section study. A total of 2095 patients (1539 HD, 556 CAPD) were recruited from the nine largest dialysis centres in China. Persons in medical centres for disease screening were selected as controls. Patients maintained on HD were dialyzed twice or thrice weekly. CAPD patients used lactate-buffered, glucose-containing solutions. The patients' data were abstracted from the medical record. The serum levels of AOPP were determined by spectrophotometric detection. RESULTS: The levels of AOPP were significantly elevated in both HD and CAPD patients compared to healthy controls. Accumulation of AOPP was more significant in HD compared to CAPD population. Meanwhile, AOPP accumulation was associated with the presence of ischaemic heart disease (IHD) only in HD, but not CAPD patients. A higher proportion of IHD was found in the HD population among those with higher levels of AOPP in each category of age and irrespective of the presence or absence of high triglyceride. Multivariate regression analysis indicated that accumulation of AOPP was an independent risk factor for IHD in HD population. CONCLUSION: Accumulation of AOPP was more significant in HD compared to CAPD patients. The level of AOPP was independently associated with IHD only in HD patients.

The receptor of advanced glycation end products plays a central role in advanced oxidation protein products-induced podocyte apoptosis.

The accumulation of plasma advanced oxidation protein products (AOPPs) is prevalent in chronic kidney disease. We previously showed that accumulation of AOPPs resulted in podocyte apoptosis and their deletion by a cascade of signaling events coupled with intracellular oxidative stress. The transmembrane receptor that specifically transmits the AOPPs' signals to elicit cellular activity, however, remains unknown. Using co-immunoprecipitation and immunofluorescence, we found that AOPPs colocalized and interacted with the receptor of advanced glycation end products (RAGE) on podocytes. Blocking RAGE by anti-RAGE immunoglobulin G or its silencing by siRNA significantly protected podocytes from AOPPs-induced apoptosis both in vitro and in vivo and ameliorated albuminuria in AOPPs-challenged mice. AOPPs-induced activation of nicotinamide adenine dinucleotide phosphate oxidase and the excessive generation of intracellular superoxide were largely inhibited by anti-RAGE immunoglobulin G or RAGE siRNA. Moreover, blockade of RAGE decreased the activation of the p53/Bax/caspase-dependent proapoptotic pathway induced by AOPPs. Thus, AOPPs interact with RAGE to induce podocyte apoptosis and this, in part, may contribute to the progression of chronic kidney disease.

VEGF ameliorates tubulointerstitial fibrosis in unilateral ureteral obstruction mice via inhibition of epithelial-mesenchymal transition.

AIM: Vascular endothelial growth factor (VEGF) has been shown to be a survival factor for renal tubular epithelial cells. In the present study, we investigated whether administration of VEGF ameliorates tubulointerstitial fibrosis in a mouse model of unilateral ureteral obstruction (UUO). METHODS: Thirty-six male CD-1 mice were randomly divided into three groups: sham-operation, UUO and UUO+VEGF group. VEGF (50 µg/kg) was subcutaneously injected twice daily from d 1 to d 14. Mice in each group were killed at d 3, 7, or 14 after the operation, and the tubulointerstitial fibrosis was histopathologically evaluated. Human proximal tubular epithelial cells (HK-2) were used for in vitro study. The expression levels of α-SMA, E-cadherin, TGF-ß1, CTGF, and BMP-7 in the kidney were determined using Western blot and RT-PCR. RESULTS: In the UUO mice, the degree of interstitial fibrosis was dramatically increased in a time-dependent manner. At d 3, 7, and 14, both the mRNA and protein expression levels for α-SMA, TGF-ß1, and CTGF were significantly upregulated, whereas those for E-cadherin and BMP-7 were significantly downregulated. At d 3 and 7, VEGF treatment significantly reduced interstitial fibrosis and the expression levels for α-SMA, TGF-ß1, and CTGF, while significantly increased the expression of E-cadherin and BMP-7, as compared with the UUO mice. At d 14 after operation, no significant differences were observed in the expression of the examined markers between VEGF-treated mice and UUO mice, with the exception of CTGF. In HK-2 cells, VEGF blocked TGF-ß1-induced α-SMA and vimentin expression and restored E-cadherin expression in a dose-dependent manner. CONCLUSION: VEGF may ameliorate renal tubulointerstitial fibrosis at the early stage in UUO mice. This effect may be related to inhibition of VEGF on renal tubular epithelial-mesenchymal transition (EMT).

Detection of advanced oxidation protein products in patients with chronic kidney disease by a novel monoclonal antibody.

Advanced oxidation protein products (AOPP) as a biomarker of oxidative stress has been demonstrated in chronic kidney disease (CKD) patients; however, current methods to detect the accumulation of AOPP in serum and in tissues are limited and unreliable. This study generated a monoclonal antibody (mAb) designated 3F2, that reacts specifically with hypochlorous acid (HOCl)-modified proteins, but not with the native forms or with other types of oxidative modifications. Notably, mAb 3F2 recognizes the AOPP deposited in renal tissues of AOPP-treated rats and of patients with different kinds of CKD. Moreover, this mAb can almost completely inhibit the production of reactive oxygen species in RAW264.7 cells induced by AOPP (p < 0.001). In conclusion, mAb 3F2 can be used to detect AOPP specifically in serum and in tissues, and this antibody can potentially provide an important tool and new insight into research on diseases related to oxidative stress.

Numb protects renal proximal tubular cells from puromycin aminonucleoside-induced apoptosis through inhibiting Notch signaling pathway.

Numb was originally discovered as an intrinsic cell fate determinant in Drosophila by antagonizing Notch signaling. The present study is to characterize the role of Numb in oxidative stress-induced apoptosis of renal proximal tubular cells. Exposure of NRK52E cells to puromycin aminonucleoside (PA) resulted in caspase 3-dependent apoptosis. Numb expression was downregulated by PA in a time- and dose-dependent manner. Knocking down endogenous Numb by siRNA sensitized NRK52E cells to PA-induced apoptosis, whereas overexpressing Numb protected NRK52E cells from PA-induced apoptosis. Moreover, PA activated Notch signaling in a time- and dose-dependent manner as indicated by increased expression of the intracellular domain of Notch and Hes-1. Notch signaling inhibitor DAPT significantly attenuated Numb siRNA-augmented apoptosis. On the other hand, overexpression of intracellular domain of Notch1 could reverse the protective effect of Numb on PA-induced apoptosis. Taken together, our data demonstrated that, in renal proximal tubular cells, Numb functions as a protective molecule on PA-induced apoptosis through antagonizing Notch signaling activity.

Advanced oxidation protein products decrease expression of nephrin and podocin in podocytes via ROS-dependent activation of p38 MAPK.

Accumulation of plasma advanced oxidation protein products (AOPPs) promotes progression of proteinuria and glomerulosclerosis. To investigate the molecular basis of AOPPs-induced proteinuria, normal Sprague-Dawley rats were treated with AOPPs-modified rat serum albumin. The expression of glomerular podocyte slit diaphragm (PSD)-associated proteins, nephrin and podocin, was significantly decreased coincident with the onset of albuminuria in rats treated with AOPPs. Chronic inhibition of NADPH oxidase by apocynin prevented down-regulation of nephrin and podocin and decreased albuminuria in AOPPs-challenged rats. This suggested that accumulation of AOPPs promotes proteinuria, possibly via down-regulating the expression of PSD-associated proteins.

[Estrogen reduces the expressions of ryanodine receptor type 1 and Cav1.3 L-type calcium channel in the vaginal smooth muscle cells of rats].

OBJECTIVE: To determine the expressions of ryanodine receptor type 1 (RyR1) and Cav1.3 L-type calcium channel (Cav1.3) in the vaginal smooth muscle cells of castrated rats and investigate the correlation of RyR1 and Cav1.3 with estrogen in female sexual dysfunction. METHODS: Forty female SD rats of 8 weeks were randomly divided into Groups A (2-week sham operation), B (4-week sham operation), C (2-week castration) and D (4-week castration). Two and 4 weeks after surgery, the serum estradiol level was determined with the automated immunochemiluminescence system and the expressions of RyR1 and Cav1.3 in the vaginal smooth muscle were detected by immunohistochemistry and RT-PCR. Gray scale ratio was used to represent the mRNA expression levels of RyR1 and Car1.3, and the optical density value to denote their protein expression levels. RESULTS: Serum estradiol was significantly decreased in Group C ([0.210 +/- 0.026] nmol/L) as compared with A ([0.505 +/- 0.053] nmol/L) (P < 0.01), and so was it in Group D ([0.130 +/- 0.031] nmol/L) in comparison with B ([0.476 +/- 0.058] nmol/L) (P < 0.01). RyR1 and Cav1.3 were expressed in all groups. The mRNA expressions of RyR1 and Cav1.3 were significantly reduced in Group C (0. 680 +/- 0.073 and 0.580 +/- 0.043) as compared with A (0.950 +/- 0.064 and 0.870 +/- 0.019) (P < 0.01), as well as in Group D (0.220 +/- 0.032 and 0.190 +/- 0.020) in comparison with B (0.890 +/- 0.072 and 0.820 +/- 0.021) (P < 0.01). The protein expressions of RyR1 and Cav1.3 were significantly down-regulated in Group C (96.67 +/- 7.75 and 87.97 +/- 6.96) as compared with A (123.69 +/- 10.66 and 106.46 +/- 8.04) (P < 0.01), and so were they in D (86.45 +/- 8.16 and 69.43 +/- 8.30) in comparison with B (109.31 +/- 9.87 and 97.38 +/- 7.56) (P < 0.01). CONCLUSION: Both RyR1 and Cav1.3 were expressed in the vaginal smooth muscle cells of the rats, and estrogen might be involved in the regulation of female sexual reaction by acting on the expressions of RyR1 and Cav1.3.

Inhibition of tubulointerstitial fibrosis by pentoxifylline is associated with improvement of vascular endothelial growth factor expression.

AIM: Recent information indicates that pentoxifylline (PTX) has the ability to suppress inflammation and profibrotic cell proliferation. In this study, we investigated the effect of PTX on tubulointerstitial fibrosis and the expression of vascular endothelial growth factor (VEGF) in a rat model of obstructive nephropathy. METHODS: Wistar rats with left ureteral ligation were divided into control and PTX-treated groups. The histopathologic degree of tubulointerstitial fibrosis was scored with PAS and Masson-stained sections. The protein and mRNA for vascular endothelial growth factor (VEGF) were semiquantitatively measured with immunohistochemistry and RT-PCR. The protein for transforming growth factor beta1 (TGFbeta1) and hypoxia-induced factor 1 alpha (HIF-1alpha) was determined by Western blot. RESULTS: Compared with the control group, PTX treatment reduced fibrosis scores at d 7 and d 14 (P<0.05). The reduction was accompanied by inhibited expression of transforming growth factor-beta 1 (TGFbeta1), a key cytokine in tubulointerstitial fibrogenesis (P<0.01). Meanwhile, VEGF protein and mRNA in the kidney were increased in the PTX-treated group compared with the control group (P<0.01). PTX up-regulated expression of VEGF mRNA in a dose- and time-dependent manner in cultured HK-2 cells (P<0.01). However, expression of HIF-1alpha (a key transcription factor for VEGF gene expression) was unchanged by PTX treatment. PTX prolonged the half-life of VEGF mRNA by a 1.07-fold increase. CONCLUSIONS: PTX inhibited tubulointerstitial fibrosis in a rat model of obstructive nephropathy while preventing loss of VEGF. PTX up-regulated expression of VEGF mRNA through stabilization of its mRNA in cultured renal tubular epithelial cells.

Evidence for adipose-muscle cross talk: opposing regulation of muscle proteolysis by adiponectin and Fatty acids.

Illnesses associated with insulin resistance exhibit increases in whole-body protein degradation and amino acid oxidation. However, the mechanisms stimulating muscle catabolism under these conditions are not clear. Because insulin resistance is associated with accumulation of lipids in muscle, we measured protein degradation in muscles of mice fed a high-fat diet. Muscle protein catabolism was accelerated on the high-fat diet, and this was associated with an increase in plasma free fatty acid and a decrease in plasma levels of the adipocyte-derived cytokine adiponectin. To evaluate how free fatty acids influence adiponectin-mediated changes in muscle protein breakdown we examined C2C12 skeletal muscle cells exposed to free fatty acids. Both saturated fatty acids (palmitate) and unsaturated fatty acids (oleate) increased protein degradation (25 and 18%, respectively) in part by activating the E3 ubiquitin ligases. Adenovirus-mediated overexpression of adiponectin blocked fatty acid-induced protein degradation in C2C12 cells. Palmitate activated the E3 ubiquitin ligases by suppressing insulin receptor substrate-1/Akt signaling in the C2C12 muscle cells, whereas adiponectin attenuated the E3 ubiquitin ligase activation by increasing both insulin receptor substrate-1 tyrosine phosphorylation and Akt Ser473 phosphorylation. In related experiments, adiponectin overexpression decreased TNFalpha and IL-6 expression in 3T3-L1 adipocytes, whereas exposure to free fatty acids had the opposite effect. We conclude that the balance between free fatty acids and adiponectin impacts muscle proteolysis in insulin-resistant conditions and suggest a role for adipose tissue-muscle cross talk in diabetes and obesity.

[Effect of bone morphogenetic protein-7 on monocyte chemoattractant protein-1 induced epithelial-myofibroblast transition and TGF-beta1-Smad 3 signaling pathway of HKC cells].

OBJECTIVE: To examine the effect of Bone Morphogenetic protein-7 (BMP-7) on Monocyte chemoattractant protein-1 (MCP-1) induced epithelial-myofibroblast transition (EMT) in cultured renal proximal tubular cells (HK-2) and the relationship between TGF-beta1-smad 3 expressions and MCP-1 induced EMT. METHODS: The cultured HK-2 cells were divided into six groups: a, negative control, b, treated with TGF-beta1 (5 ng/ml) as positive control, c, treated with MCP-1 (0.1, 1, 10, 50 ng/ml), d, treated with BMP-7 (0.1, 1, 10, 50 ng/ml), e. co-treated with MCP-1 (1 ng/ml) and MCP-1 neutralized antibody (1 ng/ml), f. co-treated with MCP-1 (1 ng/ml) and BMP-7 (50 ng/ml). alpha-Smooth Muscle Actin (alpha-SMA) mRNA expression of HK-2 cells was assessed with RT-PCR. Secretion of type I collagen was assessed with RT-PCR and ELISA, respectively. TGF-beta1 and Smad 3 expressions were assessed with Western blot. RESULTS: alpha-SMA mRNA expression significantly increased in HK-2 cells treated with MCP-1 (0.1, 1 ng/ml) compared with negative controls (5.97 +/- 0.35, 23.36 +/- 1.37 vs. 0.59 +/- 0.38, P < 0.01). alpha-SMA mRNA expression of HK-2 cells concomitantly treated with MCP-1 neutralized antibody or BMP-7 (50 ng/ml) and MCP-1 (1 ng/ml) significantly decreased than that in cells treated with MCP-1 (1 ng/ml) alone (1.93 +/- 0.34, 13.59 +/- 0.38 vs. 36.36 +/- 1.37, P < 0.01). Secretion of type I collagen of the cells treated with MCP-1 (0.1, 1 ng/ml) markedly increased compared with negative control (1751 +/- 34, 1876 +/- 45 vs. 1450 +/- 62; P < 0.01). The secretion of type I collagen of the supernatant were also significantly lower than that in cells treated with MCP-1 (1 ng/ml) alone (1462 +/- 56, 1596 +/- 34 vs. 1876 +/- 45, P < 0.05). The expression of TGF-beta1 and Smad 3 of HK-2 cells treated with MCP-1 (1 ng/ml) were markedly higher than that of negative controls, respectively (36.31 +/- 1.37 vs. 0.75 +/- 0.16, P < 0.01; 56.98 +/- 2.61 vs. 23.05 +/- 1.82, P < 0.01). The expressions of TGF-beta1 and Smad 3 in HK-2 cells treated concomitantly with MCP-1 neutralized antibody or BMP-7 (50 ng/ml) and MCP-1 (1 ng/ml) were markedly decreased than that treated with MCP-1 alone, respectively. (4.61 +/- 0.74, 23.74 +/- 2.14 vs. 36.31 +/- 1.37, P < 0.01; 19.63 +/- 1.65, 37.06 +/- 1.82 vs. 56.98 +/- 2.61, P < 0.01). The expressions of TGF-beta1 and Smad 3 in HK-2 cells treated concomitantly with MCP-1 neutralized antibody or BMP-7 (50 ng/ml) and MCP-1 (1 ng/ml) were markedly decreased than that treated with MCP-1 alone, respectively. (4.61 +/- 0.74, 23.74 +/- 2.14 vs. 36.31 +/- 1.37, P < 0.01; 19.63 +/- 1.65, 37.06 +/- 1.82 vs. 56.98 +/- 2.61, P < 0.01). CONCLUSIONS: The results documented that MCP-1 may induce EMT of HK-2 cells in vitro, and this effect is related to up-regulated expression of TGF-beta1 and Smad 3. BMP-7 may partially inhibit MCP-1-induced EMT and this effect is related to the downregulated expression of TGF-beta1 and Smad 3 of the cells. The results also suggest that MCP-1 induced EMT may involve the TGF-beta1-independent pathway of the cells.

[Altered expression of vascular endothelial growth factor and its receptors in transdifferentiated human proximal tubular epithelial cells induced by transforming growth factor beta1].

OBJECTIVE: To examine the expression of vascular endothelial growth factor (VEGF) and its receptors (VEGFR1, VEGFR2) in transdifferentiated human proximal tubular epithelial (HK-2) cell induced by transforming growth factor beta1 (TGFbeta1). METHODS: The transdifferentiation of HK-2 cells was detected by evaluation of expression of alpha-SMA by cytoimmunochemistry and RT-PCR. The VEGF mRNA was evaluated with RT-PCR. The secreted VEGF in the culture media was measured with ELISA. The cellular VEGF, VEGFR1, and VEGFR2 were measured with Western blot. RESULTS: The immunostain of alpha-SMA were positive in HK-2 cell induced by TGFbeta1 at the concentration of 5 and 8 ng/ml for 72 h. The expression of alpha-SMA mRNA was induced by TGFbeta1 in concentration- and time-dependent manners. The expressions of mRNA and protein of VEGF were upregulated by TGFbeta1 at the concentration of 0.1 and 1 ng/ml for 72 h and at the concentration of 8 ng/ml for 12 h and 24 h when compared with the control. But expressions of mRNA and protein of VEGF were downregulated by TGFbeta1 at the concentration of 3, 5, and 8 ng/ml for 72 h and at the concentration of 8 ng/ml for 36, 48, and 72 h, respectively. Meanwhile, Protein levels of VEGFR1 and VEGFR2 were upregulated by TGFbeta1 in concentration- and time- dependent manners. CONCLUSIONS: Increased expression of VEGFR1 and VEGFR2 and two-phase change in VEGF expression occurred in the process of tubular epithelial transdifferentiation induced by TGFbeta1. Reduced expression of VEGF may contribute to tubular epithelial transdifferentiation in a vicious circle.

[Effect of BMP-7 on the transdifferentiation of cultured human tubular epithelial cell induced by TGF-beta1].

OBJECTIVE: To observe the effect of bone morphogenetic protein-7 (BMP-7) on the transdifferentiation of cultured human tubular epithelial cell (HKC) induced by TGF-beta1 and to elucidate its possible mechanism. METHODS: The cultured HKC cells were divided into 5 groups: serum-free group (negative control); single TGF-beta1 treated group (positive control); single BMP-7 treated group; combined TGF-beta1 and BMP-7 treated group; and BMP-7 pre-treated group. Expression of keratin of HKC cells was assessed by indirect enzyme immunohistochemistry (IEI), expression of alpha-smooth muscle actin (alpha-SMA) and E-cadherin by immunohistological method, percentage of alpha-SMA positive HKC cells by flow cytometry, and mRNA expression of alpha-SMA, TGF-beta1, and TGF-beta type II receptor by reverse transcription PCR. RESULTS: The expression of alpha-SMA and the percentage of alpha-SMA positive HKC cells markedly increased after having been treated by TGF-beta1 while the expression of E-cadherin and keratin decreased. In the group pre-treated with BMP-7 (50 ng/ml) and then added with TGF-beta1 (8 ng/ml), expression of alpha-SMA was significantly lower than in the positive control group, while expression of E-cadherin and keratin significantly higher than in the positive control group. Measurement of the percentage of alpha-SMA positive HKC found significant deference between the combined TGF-beta1 and BMP-7 treated group and the positive control group (9.7% vs 19.8%; 5.8% vs 19.8%; P < 0.05). Significant difference existed between the BMP-7 (50 ng/ml) pre-treated group and the positive control group (8.7% vs 19.8%, P < 0.05). mRNA expression of alpha-SMA was measured by RT-PCR and the results showed that it significantly decreased in the group treated or pre-treated with BMP-7 (50 ng/ml) (15% and 12% of the results in the positive control group, respectively). The mRNA expression levels of both TGF-beta1 and its type II receptor significantly decreased (28% and 19%; 47% and 36%, compared with the positive control group, respectively). CONCLUSION: Transdifferentiation of cultured renal epithelial cell induced by TGF-beta1 can be inhibittd by certain levels of BMP-7, cultured together with TGF-beta1 or pretreated. BMP-7 can prevent and inhibit the mRNA expression of TGF-beta1 and its type II receptor, which may be an important mechanism by which BMP-7 inhibit the transdifferentiation of renal tubular epithelial cell.