Candidate metabolite markers of peripheral neuropathy in Chinese patients with type 2 diabetes.

OBJECTIVES: To analyze the serum and urine metabolites present in type 2 diabetes mellitus (T2DM) patients and T2DM patients with diabetic peripheral neuropathy (DPN) and to select differentially expressed biomarkers for early diagnosis of DPN. METHODS: Serum and urine metabolites from 74 T2DM patients with peripheral neuropathy and 41 without peripheral neuropathy were analyzed using gas chromatograph system with time-of-flight mass spectrometer metabolomics to detect biomarkers of peripheral neuropathy in T2DM. RESULTS: There were increased serum triglycerides, alanine aminotransferase, and decreased C-peptide, and total cholesterol levels in T2DM patients with DPN compared to those without peripheral neuropathy. Metabolomic analysis revealed visible differences in metabolic characteristics between two groups, and overall 53 serum differential metabolites and 56 urine differential metabolites were identified with variable influence on projection (VIP) >1 and P<0.05. To further analyze the correlation between the identified metabolites and DPN, four serum metabolites and six urine metabolites were selected with VIP>2, and fold change (FC) >1, including serum ß-alanine, caproic acid, ß-alanine/L-aspartic acid, and L-arabinose/L-arabitol, and urine gluconic acid, erythritol, galactonic acid, guanidoacetic acid, cytidine, and aminoadipic acid. Furthermore, five serum biomarkers and six urine biomarkers were found to show significant changes (P<0.05, VIP>1, and FC>1) respectively in patients with mild, moderate, and severe DPN. In addition, we found that glyoxylate and dicarboxylate metabolism was a differential metabolic pathway not only between T2DM and DPN, but also among different degrees of DPN. The differential metabolites such as ß-alanine and caproic acid are expected to be biomarkers for DPN patients, and the significant changes in glyoxylate and dicarboxylate metabolism may be related to the pathogenesis of DPN. CONCLUSION: There were serum and urine spectrum metabolomic differences in patients with DPN, which could serve as biomarkers for T2DM and DPN patients.

Astragaloside IV prevents endothelial dysfunction by improving oxidative stress in streptozotocin-induced diabetic mouse aortas.

Oxidative stress serves a role in endothelial dysfunction exhibited by patients with diabetes mellitus. Astragaloside IV (AS-IV) is a major active ingredient of Radix Astragali, which is considered to exhibit vasoprotective effects through unknown mechanisms. Thus, the current study was performed to investigate the protective effects of AS-IV in streptozotocin (STZ)-induced endothelial dysfunction and to explore whether antioxidant mechanisms were involved. The protective effects of AS-IV on the endothelium-dependent relaxation and contraction of aortic rings were determined by isometric tension recordings. NADPH subunits and endothelial nitric oxide synthase (eNOS) expression was identified via western blotting. Superoxide dismutase and malondialdehyde levels were assayed using ELISA. Furthermore, the generation of reactive oxygen species (ROS) and nitric oxide (NO) was detected via dihydroethidium and 4,5-diaminofluorescein diacetate staining, respectively. The results revealed that STZ-injected mice exhibited increased aortic endothelium-dependent vasoconstriction and decreased vasorelaxation to acetylcholine. However, AS-IV treatment reversed these effects. NG-nitro-L-arginine was subsequently used to completely inhibit impaired relaxation. Accordingly, impaired NO generation was restored following AS-IV treatment by increasing eNOS phosphorylation levels. Furthermore, ROS formation was also depressed following AS-IV treatment compared with that in STZ-injected mice. AS-IV also decreased the expression of various NADPH subunits, including human neutrophil cytochrome b light chain, neutrophil cytosolic factor 1, NADPH oxidase (NOX)2, NOX4 and Rac-1. The results of the current study may provide novel evidence that diabetes-induced vascular injury arises from either the inhibition of eNOS or the activation of NOX-derived ROS generation. In addition, the results warrant further investigation into the application of AS-IV treatment, leading to the improvement of oxidative stress, in patients with diabetes exhibiting endothelial dysfunction.

Protective effects of probucol on Ox-LDL-induced epithelial-mesenchymal transition in human renal proximal tubular epithelial cells via LOX­1/ROS/MAPK signaling.

Oxidized low-density lipoprotein (Ox-LDL), as a strong oxidant, results in renal injury through multiple mechanisms. The aim of the present study was to determine the injury effects of Ox­LDL and the potential protective effects of the antioxidant reagent probucol on epithelial­mesenchymal transition (EMT) in human renal proximal tubular epithelial cells (HK­2) and to further explore the role and interrelation of lectin­like oxidized low­density lipoprotein receptor­1 (LOX­1), reactive oxygen species (ROS) and mitogen­activated protein kinase (MAPK) pathway. In the present study, concentrations of 0­100 µg/ml Ox­LDL were used to induce HK­2 cell EMT. Then, probucol (20 µmol/l) and the LOX­1 inhibitor, polyinosinic acid (250 µg/ml), were also used to pretreat HK­2 cells. Intracellular ROS activity was evaluated using the specific probe 2',7'­dichlorodihydrofluorescein diacetate (DCFH­DA). Concentration of nitric oxide (NO) was determined using a biochemical colorimetric method. Expression of E­cadherin, α­smooth muscle actin (SMA), LOX­1, NADPH oxidase 4 (NOX4), cytochrome b­245 α chain (p22phox), extracellular signal­regulated kinase (ERK), and p38 MAPK protein levels were examined by western blotting. The results revealed that Ox­LDL induced the expression of LOX­1 and α­SMA and reduced the expression of E­cadherin in a dose­dependent manner, and these effects were inhibited by polyinosinic acid or probucol pretreatment. Stimulation with 50 µg/ml Ox­LDL induced the expression of NOX4 and p22phox and increased intracellular ROS activity, but NO production in the cell supernatants was not affected. The Ox­LDL­mediated increases in Nox4 and p22phox expression and in ROS activity were inhibited by probucol pretreatment. Further investigations into the underlying molecular pathways demonstrated that ERK and p38 MAPK were activated by Ox­LDL stimulation and then inhibited by probucol pretreatment. The findings of the present study therefore suggest that Ox­LDL induced EMT in HK­2 cells, the mechanism of which may be associated with LOX­1­related oxidative stress via the ERK and p38 MAPK pathways. Notably, pretreatment with probucol inhibited the Ox­LDL­induced oxidative stress by reducing the expression of LOX­1, and blocked the progression of EMT.

HuangQi Decoction Ameliorates Renal Fibrosis via TGF-ß/Smad Signaling Pathway In Vivo and In Vitro.

OBJECTIVE: Traditional Chinese Medicine compound HuangQi decoction is widely used in clinical treatment of chronic kidney disease, but its role on renal interstitial fibrosis and the underlying mechanism remains unclear. The aim of this study is to investigate the effect of HuangQi decoction on renal interstitial fibrosis and its association with the TGF-ß/Smad signaling pathway Methods: A total of 120 C57/BL mice were randomly divided into six groups: sham group, sham plus high-dose HuangQi decoction (1.08g/kg) group, unilateral ureteral obstruction (UUO) model group, and UUO model plus low to high doses of HuangQi decoction (0.12g/kg, 0.36g/kg and 1.08g/kg respectively) groups. Animals were sacrificed 14 days after the administration and ipsilateral kidney tissue was sampled for pathologic examinations. Immunohistochemistry, PCR and western blot were used to detect the expressions of related molecules in the TGF-ß/Smad signaling pathway. TGF-ß1 was used in in vitro experiments to induce human kidney proximal tubule epithelial cells (HK2). RESULTS: HuangQi decoction improved ipsilateral kidney fibrosis in UUO mice and downregulated the expressions of TGF-ß1, TßRI, TßRII, Smad4, Smad2/3, P-Smad2/3, α-SMA, collagen type I, III and IV in a dose-dependent manner while upregulated the expression of Smad7 in the same fashion. Similar results were found in in vitro studies. CONCLUSION: The protective effect of HuangQi decoction for unilateral ureteral obstruction kidney damage in mice was mediated by downregulating the TGF-ß/Smad signaling pathway.

Astragaloside IV prevents high glucose-induced podocyte apoptosis via downregulation of TRPC6.

Diabetic nephropathy (DN) is one of the most important causes of end­stage renal disease. Astragaloside IV (AS-IV) is a saponin isolated from Astragalus membranaceus, which possesses various pharmacological activities. AS­IV prevents podocyte apoptosis and ameliorates renal injury in DN; however, few studies have focused on its effects on ion channels. The transient receptor potential channel 6 (TRPC6) is an important Ca2+­permeable ion channel in podocytes, which is involved in high glucose (HG)-induced podocyte apoptosis. The aim of the present study was to investigate whether AS­IV prevented HG­induced podocyte apoptosis via TRPC6. Cultured podocytes were pre­treated with 10, 20 or 40 µM AS­IV for 1 h prior to HG exposure for 24 h. Apoptosis, cell viability, expression of TRPC6, nuclear factor of activated T cells (NFAT2) and B­cell lymphoma 2­associated X protein (Bax), as well as the intracellular Ca2+ concentration were subsequently analyzed. The results indicated that HG induced podocyte apoptosis and upregulation of TRPC6, and increased intracellular Ca2+. Furthermore, enhanced NFAT2 and Bax expression was detected. Conversely, AS­IV protected HG­induced podocyte apoptosis, downregulated TRPC6 expression and suppressed intracellular Ca2+ in HG-stimulated podocytes. AS­IV also suppressed NFAT2 and Bax expression. These results suggest that AS­IV may prevent HG-induced podocyte apoptosis via downregulation of TRPC6, which is possibly mediated via the calcineurin/NFAT signaling pathway.

Ursodeoxycholic acid and 4-phenylbutyrate prevent endoplasmic reticulum stress-induced podocyte apoptosis in diabetic nephropathy.

Endoplasmic reticulum (ER) stress, resulting from the accumulation of misfolded and/or unfolded proteins in ER membranes, is involved in the pathogenesis of diabetic nephropathy (DN). The aim of this study was to investigate the role of ER stress inhibitors ursodeoxycholic acid (UDCA) and 4-phenylbutyrate (4-PBA) in the treatment of DN in db/db mice. Findings have revealed that diabetic db/db mice were more hyperglycemic than their non-diabetic controls, and exhibited a marked increase in body weight, water intake, urine volume, fasting plasma glucose, systolic blood pressure, glucose and insulin tolerance. UDCA (40 mg/kg/day) or 4-PBA (100 mg/kg/day) treatment for 12 weeks resulted in an improvement in these biochemical and physical parameters. Moreover, UDCA or 4-PBA intervention markedly decreased urinary albuminuria and attenuated mesangial expansion in diabetic db/db mice, compared with db/db mice treated with vehicle. These beneficial effects of UDCA or 4-PBA on DN were associated with the inhibition of ER stress, as evidenced by the decreased expression of BiP, phospho-IRE1α, phospho-eIF2α, CHOP, ATF-6 and spliced X-box binding protein-1 in vitro and in vivo. UDCA or 4-PBA prevented hyperglycemia-induced or high glucose (HG)-induced apoptosis in podocytes in vivo and in vitro via the inhibition of caspase-3 and caspase-12 activation. Autophagy deficiency was also seen in glomeruli in diabetic mice and HG-incubated podocytes, exhibiting decreased expression of LC3B and Beclin-1, which could be restored by UDCA or 4-PBA treatment. Taken together, our results have revealed an important role of ER stress in the development of DN, and UDCA or 4-PBA treatment may be a potential novel therapeutic approach for the treatment of DN.

HuangQi Decoction Improves Renal Tubulointerstitial Fibrosis in Mice by Inhibiting the Up-Regulation of Wnt/ß-Catenin Signaling Pathway.

OBJECT: To explore the effects of HuangQi decoction on tubulointerstitial fibrosis in mice and the Wnt/ß-catenin signaling pathway. METHODS: Unilateral ureteral obstruction (UUO) model was used. A total of 120 C57/BL mice were randomly divided into 6 groups, sham group, sham+HuangQi decoction group (1.08 g/kg), UUO group, UUO+HuangQi decoction group (0.12, 0.36, 1.08 g/kg). Immunohistochemical analysis, RT-PCR and Western blot were employed to examine the proteins and genes related to the Wnt/ß-catenin signaling pathway. RESULTS: In UUO mice models, expression levels of Wnt3,4, Frizzled4, LRP5,6, ß-catenin, LEF-1, TCF-1, Snail, MMP2,7 genes were positively correlated with the degree of renal tubulointerstitial fibrosis, while expression levels of GSK-3ß, Axin, APC, CK1 were negatively correlated. HuangQi decoction could down-regulate expression levels of Wnt3,4, Frizzled4, LRP5,6, ß-catenin, LEF-1, TCF-1, Snail, Twist, MMP2,7 and up-regulate expression levels of GSK-3ß, Axin, APC, CK1 and E-cadherin. CONCLUSION: HuangQi decoction could effectively inhibit the up-regulation of Wnt/ß-catenin signaling pathway induced by UUO, implying a possible role in improving renal interstitial fibrosis.

Reduced mir-29b-3p expression up-regulate CDK6 and contributes to IgA nephropathy.

IgA nephropathy (IgAN) is the most common glomerulonephritis and the etiology of which is complex and multiple, and the pathological damage of IgAN is diversified. MicroRNA is a kind of gene expression suppressor and recently, researchers have found that microRNAs may play an important role in the pathogenesis of IgAN. Herein, we found that miR-29b-3p not miR-29a or miR-29c was significantly down regulated in IgAN patients' renal tissues. Predicted by bioinformatics tools and confirmed by dual luciferase assay and western blot, we found that the expression of CDK6 was repressed by miR-29b-3p directly. Subsequently, we found that miR-29b-3p down-regulation caused CDK6 overexpression can promote NF-κB signal by phosphorylating p65 which may enhance inflammation during IgAN pathogenesis.

[Wenyang Huoxue Recipe up-regulates the expression of angiopoietin-1 mRNA in rats with chronic aristolochic acid nephropathy].

OBJECTIVE: To investigate the effects of Wenyang Huoxue Recipe (WRHXR), a compound traditional Chinese herbal medicine for warming yang and promoting blood flow, on the expression of angiopoietin mRNA in rats with chronic aristolochic acid nephropathy induced by Caulis Aristolochia Manshuriensis (CAM) decoction, and to explore the protection mechanism of WYHXR against kidney damage. METHODS: Twenty-eight male SD rats were randomly divided into normal control group, CAM group and WYHXR-treated group. Rats in the normal control group (n=8) and CAM group (n=10) were intragastrically administered with normal saline 10 ml/(kg.d) or CAM decoction 10 ml/(kg.d) respectively. Rats in the WYHXR-treated group (n=10) were intragastrically administered with WYHXR 30 g/(kg.d) and CAM decoction 10 ml/(kg.d). The expressions of Ang-l and Ang-2 mRNAs were detected by real-time reverse transcription polymerase chain reaction (RT-PCR) after 20-week treatment. RESULTS: Compared with the normal control group, the expression of Ang-l mRNA was significantly decreased, and the expression of Ang-2 mRNA was significantly increased in the CAM group (P<0.01). Compared with the CAM group, the expression of Ang-l mRNA was increased in the WYHXR-treated group (P<0.01). The expression of Ang-2 mRNA had no significant difference between the CAM group and the WYHXR-treated group (P>0.05). Renal pathology showed that renal damage in WYHXR-treated group was significantly reduced as compared with the CAM group. CONCLUSION: WYHXR can up-regulate the expression of Ang-l mRNA, which may be its action mechanism in protecting the kidneys.