The level of serum albumin is associated with renal prognosis and renal function decline in patients with chronic kidney disease.

OBJECTIVE: The study's purpose is to explore the link of serum albumin on renal progression in patients with chronic kidney disease (CKD). METHODS: This study was a secondary analysis of a prospective cohort study in which a total of 954 participants were non-selectively and consecutively collected from the research of CKD-ROUTE in Japan between November 2010 and December 2011. We evaluated the association between baseline ALB and renal prognosis (initiation of dialysis or 50% decline in eGFR from baseline) and renal function decline (annual eGFR decline) using the Cox proportional-hazards and linear regression models, respectively. We performed a number of sensitivity analyses to ensure the validity of the results. In addition, we performed subgroup analyses. RESULTS: The included patients had a mean age of (66.86 ± 13.41) years, and 522 (69.23%) were male. The mean baseline ALB and eGFR were (3.89 ± 0.59) g/dL and (33.43 ± 17.97) ml/min/1.73 m2. The annual decline in eGFR was 2.65 mL/min/1.73 m2/year. 218 (28.9%) individuals experienced renal prognosis during a median follow-up period of 36.0 months. The baseline ALB was inversely linked with renal prognosis (HR = 0.61, 95%CI: 0.45, 0.81) and renal function decline (ß = -1.41, 95%CI: -2.11, -0.72) after controlling for covariates. The renal prognosis and ALB had a non-linear connection, with ALB's inflection point occurring at 4.3 g/dL. Effect sizes (HR) were 0.42 (0.32, 0.56) and 6.11 (0.98, 38.22) on the left and right sides of the inflection point, respectively. There was also a non-linear relationship between ALB and renal function decline, and the inflection point of ALB was 4.1 g/dL. The effect sizes(ß) on the left and right sides of the inflection point were -2.79(-3.62, -1.96) and 0.02 (-1.97, 1.84), respectively. CONCLUSION: This study shows a negative and non-linear association between ALB and renal function decline as well as renal prognosis in Japanese CKD patients. When ALB is lower than 4.1 g/dL, ALB decline was closely related to poor renal prognosis and renal function decline. From a therapeutic point of view, reducing the decline in ALB makes sense for delaying CKD progression.

The Role of AIF-1 in the Aldosterone-Induced Vascular Calcification Related to Chronic Kidney Disease: Evidence From Mice Model and Cell Co-Culture Model.

Increasing evidence suggests that aldosterone (Aldo) plays an essential role in vascular calcification which is a serious threat to cardiovascular disease (CVD) developed from chronic kidney disease (CKD). However, the exact pathogenesis of vascular calcification is still unclear. First, we established CKD-associated vascular calcification mice model and knockout mice model to investigate the causal relationship between allograft inflammatory factor 1 (AIF-1) and vascular calcification. Then, endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) co-culture experiments were performed to further explore the mechanisms of calcification. The results of the Aldo intervention mice model and transgenic mice model showed that Aldo could cause calcification by increasing the AIF-1 level. The results of in vitro co-culture model of ECs and VSMCs showed that AIF-1 silence in ECs may alleviate Aldo-induced calcification of VSMCs. In conclusion, our study indicated that Aldo may induce vascular calcification related to chronic renal failure via the AIF-1 pathway which may provide a potential therapeutic target.

The Crosstalk between Calcium Ions and Aldosterone Contributes to Inflammation, Apoptosis, and Calcification of VSMC via the AIF-1/NF-κB Pathway in Uremia.

Vascular calcification is a major complication of maintenance hemodialysis patients. Studies have confirmed that calcification mainly occurs in the vascular smooth muscle cells (VSMC) of the vascular media. However, the exact pathogenesis of VSMC calcification is still unknown. This study shows that the crosstalk between calcium and aldosterone via the allograft inflammatory factor 1 (AIF-1) pathway contributes to calcium homeostasis and VSMC calcification, which is a novel mechanism of vascular calcification in uremia. In vivo results showed that the level of aldosterone and inflammatory factors increased in calcified arteries, whereas no significant changes were observed in peripheral blood. However, the expression of inflammatory factors markedly increased in the peripheral blood of uremic rats without aortic calcification and gradually returned to normal levels with aggravation of aortic calcification. In vitro results showed that there was an interaction between calcium ions and aldosterone in macrophages or VSMC. Calcium induced aldosterone synthesis, and in turn, aldosterone also triggered intracellular calcium content upregulation in macrophages or VSMC. Furthermore, activated macrophages induced inflammation, apoptosis, and calcification of VSMC. Activated VSMC also imparted a similar effect on untreated VSMC. Finally, AIF-1 enhanced aldosterone- or calcium-induced VSMC calcification, and NF-κB inhibitors inhibited the effect of AIF-1 on VSMC. These in vivo and in vitro results suggest that the crosstalk between calcium ions and aldosterone plays an important role in VSMC calcification in uremia via the AIF-1/NF-κB pathway. Local calcified VSMC induced the same pathological process in surrounding VSMC, thereby contributing to calcium homeostasis and accelerating vascular calcification.

Upregulation of allograft inflammatory factor­1 expression and secretion by macrophages stimulated with aldosterone promotes renal fibroblasts to a profibrotic phenotype.

Macrophages have been identified as a key cell type in the pathogenesis of renal interstitial fibrosis (RIF). However, the mechanism through which macrophages drive fibrosis remains unclear. The current study focuses on the effects and possible underlying mechanism of allograft inflammatory factor­1 (AIF­1), an inflammation­responsive scaffold protein expressed and secreted by macrophages, in promoting fibroblasts to a profibrotic phenotype. In vivo experiments indicated that AIF­1, CD68 and α­smooth muscle actin (α­SMA) were upregulated in kidney tissues of mice subjected to unilateral ureteric obstruction, while their expressions were inhibited by an aldosterone receptor antagonist, spironolactone. Double immunofluorescence staining revealed that AIF­1 expression co­localized with CD68­positive macrophages in the renal interstitium, indicating that AIF­1 expression in macrophages was increased in the RIF animal model. Furthermore, to identify the role of AIF­1 in promoting fibrosis, its expression and secretion by the RAW264.7 macrophage cell line were detected in vitro. The expression levels of α­SMA, phosphorylated p38 (p­p38) and fibronectin (FN) in fibroblasts were examined subsequent to co­culture with macrophages. The increase in AIF­1 expression and secretion was confirmed in RAW264.7 cells in response to aldosterone. After 72 h of co­culture between fibroblasts and macrophages stimulated with aldosterone, the α­SMA expression was induced in fibroblasts, with significantly increased expression levels of FN and p­p38 observed. In addition, AIF­1 expression was reduced by stable transfection of RAW264.7 cells with AIF­1 small interfering RNA, resulting in significantly reduced expression levels of α­SMA, p­p38 and FN in fibroblasts co­cultured with macrophages as compared with normal macrophages. These findings indicate that the expression of AIF­1 in macrophages is critical for the activation of renal fibroblasts to a profibrotic phenotype. AIF­1 expression was upregulated in macrophages, and may be a novel mechanism linking macrophages to the promotion of RIF via the p38 signaling pathway.

Up-regulation of microRNA-93 inhibits TGF-ß1-induced EMT and renal fibrogenesis by down-regulation of Orai1.

TGF-ß1-induced excessive deposition of ECM and EMT process of tubular epithelial cells play critical roles in the development and progression of fibrosis in diabetic nephropathy (DN). Orai1 has been demonstrated to be involved in TGF-ß1-induced EMT via TGF-ß/Smad3 pathway. We are aimed to explore the effects of miR-93 on TGF-ß1-induced EMT process in HK2 cells. In this study, our data showed that miR-93 was dramatically decreased in renal tissues of patients with DN and TGF-ß1-stimulated HK2 cells. Moreover, the decreased level of miR-93 was closely associated with the increased expression of Orai1. Overexpression of miR-93 decreased Orai1 expression, and then suppressed TGF-ß1-mediated EMT and fibrogenesis. Next, we predicted that the Orai1 was a potential target gene of miR-93, and demonstrated that miR-93 could directly target Orai1. SiRNA targeting Orai1 was sufficient to suppress TGF-ß1-induced EMT and fibrogenesis in HK2 cells. Furthermore, Overexpression of Orai1 partially reversed the protective effect of miR-93 overexpression on TGF-ß1-mediated EMT and fibrogenesis in HK2 cells. Taken together, Orai1 and miR-93 significantly impact on the progression of TGF-ß1-mediated EMT and fibrogenesis in HK2 cells, and they may represent novel targets for the prevention strategies of fibrosis in the context of DN.

MicroRNA-34b/c inhibits aldosterone-induced vascular smooth muscle cell calcification via a SATB2/Runx2 pathway.

Increasing evidence shows that aldosterone and specific microRNAs (miRs) contribute to vascular smooth muscle cell (VSMC) calcification. In this study, we aim to explore the mechanistic links between miR-34b/c and aldosterone in VSMC calcification. VSMC calcification models were established both in vitro and in vivo. First, the levels of aldosterone, miR-34b/c and special AT-rich sequence-binding protein 2 (SATB2) were measured. Then, miR-34b/c mimics or inhibitors were transfected into VSMCs to evaluate the function of miR-34b/c. Luciferase reporter assays were used to demonstrate whether SATB2 was a direct target of miR-34b/c. Aldosterone and SATB2 were found to be markedly upregulated during VSMC calcification, whereas miR-34b/c expression was downregulated. Treatment with the mineralocorticoid receptor (MR) antagonist eplerenone inhibited VSMC calcification. In aldosterone-induced VSMC calcification, miR-34b/c levels were downregulated and SATB2 protein was upregulated. Furthermore, miR-34b/c overexpression alleviated aldosterone-induced VSMC calcification as well as inhibited the expression of SATB2 protein, whereas miR-34b/c inhibition markedly enhanced VSMC calcification and upregulated SATB2 protein. In addition, luciferase reporter assays showed that SATB2 is a direct target of miR-34b/c in VSMCs. Overexpression of SATB2 induced Runx2 overproduction and VSMC calcification. Therefore, miR-34b/c participates in aldosterone-induced VSMC calcification via a SATB2/Runx2 pathway. As miR-34b/c appears to be a negative regulator, it has potential as a therapeutic target of VSMC calcification.

MicroRNA-let-7f-1 is induced by lycopene and inhibits cell proliferation and triggers apoptosis in prostate cancer.

Previous studies have suggested that lycopene has cytotoxic effects in a variety of types of human cancer. An improved understanding of the mechanisms underlying the anticancer effects of lycopene may provide novel therapeutic targets for cancer treatment. PC3 cells were treated with different concentrations of lycopene for 24 and 48 h, the level of protein kinase B (AKT2) was detected by reverse transcription­quantitative polymerase chain reaction (RT­qPCR) and western blotting. Additionally, the expression levels of microRNA (miR)­let­7f­1 were measured using RT­qPCR. miR­let­7f­1 function was analyzed using cell proliferation and apoptosis assays in gain­ and loss­of­function experiments. It was observed that lycopene downregulated the expression of AKT2 and upregulated the expression of miR­let­7f­1 in PC3 cells. Re­introduction of miR­let­7f­1 into PC3 cells was able to inhibit cell proliferation and induce apoptosis. Further investigation indicated that miR­let­7f­1 targeted AKT2 in PC3 cells and upregulation of AKT2 could attenuate the effects induced by miR­let­7f­1. The results of the current study indicate that miR­let­7f­1 is involved in the anticancer effects of lycopene and serves an important role in the inhibition of prostate cancer progression through the downregulation of AKT2.

Aldosterone-induced inflammatory response of mesangial cells via angiotension II receptors.

INTRODUCTION: In this study, we investigated whether AngII receptors (AT1a and AT2) contributed to the development of the aldosterone-induced inflammatory response of rat mesangial cells (RMCs). MATERIALS AND METHODS: RMCs were isolated from the glomeruli of normal or diabetic rats which were produced by injection of streptozotocin, and cultured in high-glucose media. In order to evaluate the effects of aldosterone, the expression of AT1a, AT2, NF-κB and MCP-1 was detected. In addition, in order to evaluate the role of Ang II receptors, AT1a and AT2 genes were blocked and the expression of NF-κB and MCP-1 was detected. Moreover, for assessing the relationship between NF-κB and MCP-1, the NF-κB gene was blocked and MCP-1 expression was detected. RESULTS: Aldosterone significantly increased AT1a, AT2, NF-κB and MCP-1 levels in RMCs in a dose-dependent manner, whereas eplerenone (EPI), a selective aldosterone antagonist, partly inhibited the effects of aldosterone. When AT1a and AT2 genes were blocked, the expression of NF-κB and MCP-1 was greatly inhibited. Moreover, when the NF-κB gene was silenced, the expression of MCP-1 was reduced. CONCLUSION: We demonstrated that aldosterone induced an inflammatory response in RMCs cultured in high-glucose media via the AT1a and AT2 pathways.

The aldosterone receptor antagonist spironolactone prevents peritoneal inflammation and fibrosis.

Peritoneal fibrosis is a complication of patients with long-term continuous ambulatory peritoneal dialysis (CAPD). Reports have indicated that angiotensin (Ang) II may correlate with the development of peritoneal fibrosis. However, it is unknown whether aldosterone also has a role in the development of peritoneal inflammation and fibrosis. The aim of the present study was to clarify the role of aldosterone in peritoneal inflammation and fibrosis. A rat model of peritoneal inflammation and fibrosis was established by daily intraperitoneal injection of dialysates and lipopolysaccharide in a 4-day interval over a period of 7 days. The animals were randomly assigned to five groups as follows: control (C); peritoneal dialysis (PD); peritoneal dialysis-spironolactone (PD-S); peritoneal dialysis-cilazapril (PD-C); and peritoneal dialysis-spironolactone-cilazapril (PD-SC). After 30 days, the TGF-ß1 concentration in dialysates from all treatment groups was determined by ELISA. The histopathology of the parietal peritoneum was examined, and the expression of MCP-1, c-Jun, fibronectin (FN) and TGF-ß1 in the abdominal membrane was determined by immunohistochemistry. Mineralocorticoid receptor (MR), 11ß-hydroxysteroid dehydrogenase type 2 (11ß-HSD2) and CYP11B2 (aldosterone synthase) were analyzed by real time-PCR. Collagen deposition was significantly higher in PD compared with the other groups. The expression of MR, 11ß-HSD2 and CYP11B2 was significantly higher in PD compared with the other groups. Spironolactone and/or cilazapril treatment partially ablated the increase in monocyte chemoattractant protein (MCP)-1, p-c-Jun, transforming growth factor (TGF)-ß1, FN, MR, 11ß-HSD2 and CYP11B2. Furthermore, treatment with spironolactone and/or cilazapril also reduced the infiltration of CD-4- and ED-1-positive cells in rat peritoneal tissues after peritoneal fibrosis. Exogenous aldosterone may have a key role in the development of peritoneal inflammation and fibrosis. Spironolactone decreased peritoneal inflammation and fibrosis, which was associated with reduced secretion from peritoneal macrophages, inactivation of the c-Jun N-terminal kinase (JNK) pathway and subsequent downregulation of the expression of TGF-ß1.