Hyperuricemic Nephropathy Research Articles

Total glucosides of herbaceous peony (Paeonia lactiflora Pall.) flower attenuate adenine- and ethambutol-induced hyperuricaemia in rats

Ethnopharmacological relevanceHerbaceous peony (Paeonia lactiflora Pall.) flower has been used widely in dietotherapy in China and other countries. It has good ethnopharmacological value in the treatment of various metabolic diseases. However, the molecular mechanisms by which it lowers serum uric acid are unknown. The development of pharmaceutical resources is very important. Here, we sought to elucidate the mode of action of herbaceous peony in terms of reducing uric acid levels.Aim of the study: In the present research, the effects of the total glucosides of herbaceous peony flower were investigated in a rat hyperuricaemia model. Another aim of the study was to clarify the mechanism by which herbaceous peony flower (TGPF) lowers serum uric acid levels. Materials and methodsA hyperuricaemic rat model was induced via intragastric administration of 100 mg/kg adenine and 250 mg/kg ethambutol hydrochloride (EH) for 23 d. Then TongFengShu 600 mg/kg, allopurinol 42 mg/kg, or TGPF (50 mg/kg, 100 mg/kg, or 200 mg/kg) was administered 1 h after the adenine and EH treatments. ResultsTGPF improved weight loss and decreased serum UA, XOD, MCP-1, TNF-α, Cr, and BUN in the rats with hyperuricaemic nephropathy. TGPF downregulated renal URAT1 and GLUT9, upregulated renal OAT1, and ameliorated histopathological changes in the thymus, spleen, and kidney. ConclusionTGPF is promising as a therapeutic agent against hyperuricaemia. It regulates the uric acid transporters and diminished serum uric acid levels, and alleviates renal pathology associated with hyperuricaemia.

P0700FLAVONOID FISETIN ALLEVIETES RENAL DYSFUNCTION IN A SEVERE MOUSE MODEL OF HYPERURECEMIC NEPHROPATHY

Abstract Background and Aims Flavonoid Fisetin is a natural product that has a wide distribution in many fruits and vegetables and exerts anti-cancer, anti-oxidant, anti-inflammatory and anti-mitotic effects. The renal protective effects of fisetin have been confirmed in models of diabetic nephropathy, cisplatin-induced AKI, ischemia reperfusion kidney injury and lupus nephritis. The current study instigates the protective effect of fisetin in a severe mouse model of hyperuricemic nephropathy (HN) and explores its underlying mechanisms. Method Twenty-four C57BL6 mice were randomly divided into four groups: Control, Model, Allopurinol and fisetin. HN was established by oral administration of mixture of adenine (160 mg/kg/d)/potassium oxonate (2400 mg/kg/d) every other day for 28 days. Fisetin (100 mg/kg/d) and allopurinol (10 mg/kg/d) was given by gavage simultaneously. At the end of the treatment, serum uric acid, kidney functions (serum creatinine and BUN) kidney pathological changes, as well as underlying mechanisms were investigated by biochemical assay, histopathological score, RT-PCR, and western blotting analysis. Results Oral administration of fisetin to HN mice lowered serum uric acid and improved renal functions. Renal fibrosis and inflammation in HN mice were attenuated by fisetin treatment. fisetin alleviated extracellular matrix deposition and reduced the release of pro-inflammatory cytokine IL-6, IL-1β, TNF-α and in the kidneys of HN mice. Furthermore, fisetin inhibited the activation of TGF-β and STAT3 signaling pathways in the kidneys of HN mice Conclusion These data demonstrated that fiseitn exhibited renoprotective effect in a severe mouse model of hyperuricemic nephropathy (HN). Fisetin exerted anti-inflammatory and antifibrotic effects in HN mice, which might be associated with its inhibition on TGF-β /Smad3 and STAT3 pathways.

P0170ETHANOL EXTRACT OF LIRIODENDRON CHINENSE(HEMSL.) SARG BARKS ALLEVIATES HYPERURICEMIC NEPHROPATHY VIA MEDIATING RENAL FIBROSIS AND INFLAMMATION

Abstract Background and Aims The barks of Liriodendron Chinense (Hemsl.) Sarg is used in folk for expelling “wind and dampness”, alleviating rheumatic arthralgia in traditional Chinese medicine. The aim of the study was to evaluate the protective effect of ethanol extract of the barks of Liriodendron Chinense (Hemsl.) Sarg (EELC) in a mouse model of hyperuricemic nephropathy (HN) and the mechanisms involved. Method EELC at a respective dose of 250 mg/kg/d or 500 mg/kg/d were orally administered to HN mice induced by a mixture of adenine (160 mg/kg/d)/potassium oxonate (2.4 g/kg/d) for 21 days. At the end of the treatment, serum uric acid, kidney functions (serum creatinine, BUN and urine microalbumin), 24-h urine uric acid excretion, as well as kidney pathological changes were investigated by biochemical assay, histopathological score, immunofluorescence and histochemistry, RT-PCR, and western blotting analysis. Results Oral administration of EELC to HN mice lowered serum uric acid, improved renal functions and attenuated renal fibrosis, especially the high-dose of EELC. EELC treatment also inhibited the activation of NF-κB, ASK1/JNK/c-Jun, JAK2/STAT3 signaling pathways and reduced the release of pro-inflammatory cytokine TNF-α in the kidneys of HN mice. Furthermore, EELC remarkably increased urine uric acid excretion of HN mice, which may be achieved by the upregulation of organic anion transporter 1 (OAT1), OAT3 and ATP-binding cassette subfamily G member 2 (ABCG2) proteins. Conclusion EELC alleviated the progression of HN by suppressing the activation of NF-κB, ASK1/JNK/c-Jun and JAK2/STAT3 signaling pathway, reducing the infiltration of inflammatory factors and uric acid accumulation in the kidney. Figure Date are represented as the mean ± SD. *p<0.05,**p<0.01,***p<0.001, ****p<0.0001 vs. control, §p <0.05, §§p<0.01, §§§p<0.001,§§§§p<0.0001 vs. model.

Treatment with a PPAR-γ Agonist Protects Against Hyperuricemic Nephropathy in a Rat Model.

PurposeHyperuricemia is an independent risk factor for renal damage and can promote the progression of chronic kidney disease (CKD). In the present study, we employ a rat model to investigate the effects of rosiglitazone (RGTZ), a peroxisome proliferator-activated receptor-gamma agonist, on the development of hyperuricemic nephropathy (HN), and we elucidate the mechanisms involved.MethodsAn HN rat model was established by oral administration of a mixture of adenine and potassium oxonate daily for 3 weeks. Twenty-four rats were divided into 4 groups: sham treatment, sham treatment plus RGTZ, HN, and HN treated with RGTZ.ResultsAdministration of RGTZ effectively preserved renal function, decreased urine microalbumin, and inhibited interstitial fibrosis and macrophage infiltration in a rat HN model. RGTZ treatment also inhibited TGF-β and NF-κB pathway activation, decreased expression of fibronectin, collagen I, α-SMA, vimentin, MCP-1, RANTES, TNF-α, and IL-1β, and increased E-cadherin expression in the kidneys of HN rats. Furthermore, RGTZ treatment preserved expression of OAT1 and OAT3 in the kidney of HN rats.ConclusionRGTZ attenuates the progression of HN through inhibiting TGF-β signaling, suppressing epithelial-to-mesenchymal transition, reducing inflammation, and lowering serum uric acid levels by preserving expression of urate transporters.

SO013CRUCIAL ROLE OF SERUM RESPONSE FACTOR IN EPITHELIAL-MESENCHYMAL TRANSITION OF RENAL TUBULAR EPITHELIAL CELLS IN HYPERUREICEMIC NEPHROPATHY

Abstract Background and Aims To investigate the role of serum response factor (SRF) in epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells (TECs) in hyperuricemic nephropathy (HN). Method The expression of SRF, epithelial markers (E-cadherin and ZO-1) and mesenchymal markers (fibronectin, α-SMA, FSP-1) was examined in rat renal tubular epithelial cells (NRK-52E cells) or renal medulla tissues following uric acid (UA). SRF was upregulated by SRF plasmids and downregulated by CCG-1423(a small molecule inhibitor of SRF) to investigate how SRF influenced EMT in TECs of HN. Oxonic acid (OA) was used to generate HN in rats. Results Conclusion Together, increased SRF activity promotes EMT and dysfunction of TECs in HN. Targeting SRF by small molecule inhibitor may be an attractive therapeutic strategy for HN.

Delayed treatment with an autophagy inhibitor 3-MA alleviates the progression of hyperuricemic nephropathy

Autophagy is a cell self-renewal process that relies on the degradation of the cytoplasmic proteins or organelles of lysosomes and is associated with development of numerous diseases. However, the therapeutic effect of autophagy inhibition on hyperuricemic nephropathy (HN) and the underlying mechanisms are still unknown. Here, we investigated the effect of delayed treatment with 3-methyladenine (3-MA), a specific autophagy inhibitor, on the development of HN in a rat model. Administration of 3-MA at 21 days following after uric acid injury protected kidney from hyperuricemic-related injuries, as demonstrated by improving renal dysfunction and architecture damage, blocking Beclin-1 and LC3II/I and decreasing the number of autophagic vacuoles. Late treatment with 3-MA was also effective in attenuating renal fibrosis as evidenced by reducing ECM protein deposition, blocking epithelial-to-mesenchymal transition (EMT) and decreasing the number of renal epithelial cells arrested at the G2/M phase of cell cycle. Injury to the kidney resulted in increased expression of TGFβ receptor I, and phosphorylation of Smad3, 3-MA significantly abrogated all these responses. Moreover, inhibition of autophagy suppressed mitochondrial fission, downregulated the expression of Dynamin-related protein 1 (Drp-1), Cofilin and F-actin, and alleviated cell apoptosis. Finally, 3-MA effectively blocked STAT3 and NF-κB phosphorylation and suppressed infiltration of macrophages and lymphocytes as well as release of multiple profibrogenic cytokines/chemokines in the injured kidney. Taken together, these findings indicate that hyperuricemia-induced autophagy is critically involved in the activation of renal fibroblasts, EMT, mitochondrial fission and apoptosis of tubular epithelial cells and development of renal fibrosis. Thus, this study provides evidence for autophagy inhibitors as the treatment of HN patients.

Mangiferin Ameliorates Hyperuricemic Nephropathy Which Is Associated With Downregulation of AQP2 and Increased Urinary Uric Acid Excretion.

Hyperuricemia is characterized by abnormally high level of circulating uric acid in the blood and is associated with increased risk of kidney injury. The pathophysiological mechanisms leading to hyperuricemic nephropathy (HN) involve oxidative stress, endothelial dysfunction, inflammation, and fibrosis. Mangiferin is a bioactive C-glucoside xanthone, which has been exerting anti-inflammatory, anti-fibrotic, and antioxidative effects in many diseases. This study aimed to evaluate the effect of mangiferin treatment in HN. In a mouse model of HN, we observed lower circulating urate levels and ameliorated renal dysfunction with mangiferin treatment, which was associated with reduced renal inflammation and fibrosis. We next investigated the mechanism of urate lowering effect of mangiferin. Metabolic cage experiment showed that mangiferin-administrated mice excreted significantly more urinary uric acid due to elevated urine output, but no marked change in urine uric acid concentration. Expressions of water channels and urate transporters were further assessed by western blot. Renal AQP2 expression was decreased, yet urate transporters URAT1, GLUT9, and OAT1 expressions were not affected by mangiferin in HN mice. Moreover, mangiferin treatment also normalized xanthine oxidase and SOD activity in HN mice, which would decrease uric acid synthesis and improve oxidative stress, respectively. Therefore, our results reveal a novel mechanism whereby mangiferin can reduce serum uric acid levels by promoting AQP2-related urinary uric acid excretion. This study suggested that mangiferin could be a multi-target therapeutic candidate to prevent HN via mechanisms that involve increased excretion and decreased production of uric acid and modulation of inflammatory, fibrotic, and oxidative pathways.

Spontaneous Tumor Lysis Syndrome in Blastoid-Variant Mantle Cell Lymphoma: Considerations for the General Internist

Spontaneous tumor lysis syndrome (SPTLS) is a rare phenomenon that can manifest in rapidly proliferating hematological malignancies and solid tumors prior to initiating cytotoxic therapy. We encountered a patient who originally presented with diffuse lymphadenopathy, abdominal distention, and dyspnea, who had laboratory abnormalities suggestive of SPTLS. His peripheral flow cytometry and lymph node biopsy revealed blastoid-variant mantle cell lymphoma. Prior to initiating chemotherapy, acute kidney injury (AKI) and uric acid had improved with intravenous fluids and the initiation of allopurinol. However, after beginning chemotherapy, the patient developed a second AKI concerning for tumor lysis syndrome (TLS). He went on to have renal recovery and did not require renal replacement therapy. With the exception of case reports, there is limited evidence to guide general medicine clinicians who encounter cases of SPTLS. Expert-based guidelines are available to guide use of rasburicase, an uricase enzyme, before initiation of chemotherapy for certain malignancies when risk for TLS is considered high. Despite these guidelines, the role of rasburicase in preventing AKI remains controversial after inconclusive results in a meta-analysis. The causative relationship between uric acid and AKI in TLS is based on a mechanism of tubular obstruction. There are also mechanisms by which uric acid may cause AKI without tubular obstruction related to acute hyperuricemic nephropathy. Further characterization of the role of uric acid in causing AKI in patients without tubular obstruction may identify new mechanisms of injury and offer insight into new treatment strategies.

Crucial role of serum response factor in renal tubular epithelial cell epithelial-mesenchymal transition in hyperuricemic nephropathy.

Objective: To explore the regulation and function of serum response factor (SRF) in epithelial-mesenchymal transition (EMT) in renal tubular epithelial cells (TECs) in hyperuricemic nephropathy (HN).Results: In NRK-52E cells treated with UA and renal medulla tissue samples from hyperuricemic rats, SRF, fibronectin, α-SMA and FSP-1 expression was upregulated, while ZO-1 and E-cadherin expression was downregulated. SRF upregulation in NRK-52E cells increased slug expression. Blockade of SRF by an SRF-specific siRNA or CCG-1423 reduced slug induction and protected TECs from undergoing EMT both in vitro and in vivo.Conclusion: Increased SRF activity promotes EMT and dysfunction in TECs in HN. Targeting SRF with CCG-1423 may be an attractive therapeutic strategy in HN.Methods: The expression of SRF, mesenchymal markers (fibronectin, α-SMA, and FSP-1), epithelial markers (ZO-1 and E-cadherin) and was examined in rat renal TECs (NRK-52E cells) or renal medulla tissue samples following uric acid (UA) treatment. SRF overexpressed with pcDNA-SRF plasmid and suppressed by CCG-1423 (a small molecule inhibitor of SRF) to study how SRF influences EMT in TECs in HN. Oxonic acid (OA) was used to establish HN in rats.

Targeting kidneys by superparamagnetic allopurinol loaded chitosan coated nanoparticles for the treatment of hyperuricemic nephrolithiasis.

The major short coming of conventional therapy system is that they can't deliver the therapeutics specifically to a site within the body without producing nonspecific toxicity. Present research aimed at developing kidney targeted allopurinol (AP) loaded chitosan coated magnetic nanoparticles (A-MNPs) for the management of hyperuricemic nephropathy manifested in the form of nephrolithiasis. The work includes preparation of magnetic nanoparticles by chemical co-precipitation method and evaluation of the prepared batches for particle size analysis, Transmission electron microscopy, entrapment efficiency, in-vitro release study etc. Further, FTIR spectroscopy, X-ray diffraction, Differential Scanning Calorimetry, Vibrational sample magnetometer (VSM) and in-vivo animal studies were also performed. VSM analysis demonstrates that the prepared nanoparticles exhibit superparamagnetic magnetic behaviour which was retained even after coating by chitosan. In-vivo studies of A-MNPs showed 19.07-fold increase in kidney uptake of AP as compared to serum post 2h of administration in mice whereas no drug was detected in kidney and serum post 2h administration of pure drug (free-form) indicating successful targeting to kidney as well as sustained release of AP from the formulated A-MNPs. The significant (p < 0.01) effectiveness of A-MNPs in management of hyperuricemic nephrolithiasis was observed through estimating pH and uric acid levels in urine and serum samples of mice. These findings were also confirmed by histological examination of isolated kidney samples. Present investigation signifies that a simple external magnetic field is enough for targeting allopurinol to kidneys by formulating A-MNPs which further offers an effective approach for management of hyperuricemic nephrolithiasis. Graphical Abstract.

Abnormal metabolism of gut microbiota reveals the possible molecular mechanism of nephropathy induced by hyperuricemia

The progression of hyperuricemia disease is often accompanied by damage to renal function. However, there are few studies on hyperuricemia nephropathy, especially its association with intestinal flora. This study combines metabolomics and gut microbiota diversity analysis to explore metabolic changes using a rat model as well as the changes in intestinal flora composition. The results showed that amino acid metabolism was disturbed with serine, glutamate and glutamine being downregulated whilst glycine, hydroxyproline and alanine being upregulated. The combined glycine, serine and glutamate could predict hyperuricemia nephropathy with an area under the curve of 1.00. Imbalanced intestinal flora was also observed. Flavobacterium, Myroides, Corynebacterium, Alcaligenaceae, Oligella and other conditional pathogens increased significantly in the model group, while Blautia and Roseburia, the short-chain fatty acid producing bacteria, declined greatly. At phylum, family and genus levels, disordered nitrogen circulation in gut microbiota was detected. In the model group, the uric acid decomposition pathway was enhanced with reinforced urea liver-intestine circulation. The results implied that the intestinal flora play a vital role in the pathogenesis of hyperuricemia nephropathy. Hence, modulation of gut microbiota or targeting at metabolic enzymes, i.e., urease, could assist the treatment and prevention of this disease.

ASSOCIATION OF URINARY LEVELS OF UROMODULIN AND UMOD RS1333226 WITH SERUM URIC ACID

Objective: It was reported that low uromodulin is associated with increased uric acid reabsorption in proximal tubule but also tubular uric acid affect uromodulin excretion. On the other hand, UMOD mutations have been identified in patients with familial juvenile hyperuricemia nephropathy and similar diseases characterized by increased levels of serum uric acid (SUA). Our objective was to find out whether urine uromodulin levels depending on UMOD polymorphism rs1333226 are associated with differences in SUA concentrations. Design and method: A group of 350 untreated subjects (men 45,9 %, mean age 40 years), subgroup of larger cohort from the ENAH study (random sample of rural population) were enrolled into the study. Subjects were divided into 3 groups based on the 33th and 77th percentiles of SUA (Median SUA levels were 210, 299, and 410 mmol/L, respectively). Urinary uromodulin levels were measured by Enzyme Linked Immunosorbent Assay (ELISA) and genotyping for UMOD rs1333226 by RT-PCR with the fluorescence-based TaqMan system. Only samples with urine creatinine in normal ranges were included in analyses. Uromodulin was indexed to urine creatinine. Results: Negative correlation between urine uromodulin and serum uric acid levels was observed (44, 36, and 30 mmol/g in the 1st, 2nd, and 3rd SUA groups (p = 0.01). There were no significant differences among GFR CKD-EPI values among groups. There was a positive correlation between BMI and SUA as well as between waist circumference and SUA. We found no difference in rs1333226 allele frequencies across 3 groups; allele A 82% and allele G 18%. Conclusions: Our findings showed a negative correlation between urinary uromodulin and SUA therefore being in agreement with previous studies reporting that uromodulin affects uric acid kidney excretion. On the other hand we did not find difference in rs1333226 allele frequencies across SUA groups which could mean that this UMOD SNP is not associated with UA reabsorption. However, this should be proven on larger number of patients.

THE NUCLEAR FACTOR OF HEPATOCYTES 1β (HNF1β)–ASSOCIATED DISEASE. CLINIC, DIAGNOSTIC, TREATMENT (LITERATURE REVIEW AND CLINICAL OBSERVATION)

Hepatocyte nuclear factor 1β (HNF1β)-associated disease is a rare autosomal dominant disease caused by various mutations in the HNF1β gene coding the hepatocyte nuclear factor 1β. HNF1β is a transcription factor that is critical for the development of kidney urogenital tract, pancreas, liver, brain, and parathyroid gland. Renal phenotype or HNF1β- nephropathy appeared to be extremely heterogenic: multicystic renal dysplasia, renal hypoplasia, unilateral renal agenesis, horseshoe kidney, atypical familial juvenile hyperuricemic nephropathy, urinary tract malformations and tubular dysfunction. Extrarenal phenotype of HNF1β-associated disease could be maturity-onset diabetes of the young (MODY), pancreatic atrophy and exocrine pancreatic dysfunction, elevated liver enzymes, neonatal cholestasis, congenital abnormalities of the genital tract, hyperparathyroidism, neurological symptoms. The multisystem phenotype makes clinical verification of the diagnosis extremely difficult. In this article, we present a clinical observation of a child with HNF1β – associated disease. The first clinical presentation of HNF1β-associated disease was ultrasound changes in the kidneys (hyperechogenic kidneys?), which were detected by prenatal ultrasonography in pregnancy. Renal ultrasound revealed polycystic kidney disease in the first days of life and bilateral medullary nephrocalcinosis by the age of three. The clinical examination showed a reduced renal function and developed Fanconi syndrome (glycosuria, low molecular proteinuria, hypophosphatemia, aminoaciduria, hyperuricosuria) in the first year of life. Also the child had a non-constant asymptomatic elevation of liver enzymes, hyperparathyroidism, osteoporosis. The diagnosis was confirmed by the results of next generation sequencing which revealed novel heterozygous mutation in exon 4 of the HNF1b gene (chr17: 36091813C&gt;T), p.Cys273Tyr (c.818G&gt;A). The identified mutation was validated by Sanger sequencing. Validation by Sanger sequencing did not reveal a chr17: 36091813C&gt;T mutation in parents, which suggested the appearance of a mutation in the child de novo.

Blockade of ERK1/2 by U0126 alleviates uric acid-induced EMT and tubular cell injury in rats with hyperuricemic nephropathy.

Extracellular signal-regulated kinases 1 and 2 (ERK1/2) are serine/threonine kinases and function as regulators of cellular proliferation and differentiation. Recently, we demonstrated that inhibition of ERK1/2 alleviates the development and progression of hyperuricemia nephropathy (HN). However, its potential roles in uric acid-induced tubular epithelial-mesenchymal transition (EMT) and tubular epithelial cell injury are unknown. In this study, we showed that hyperuricemic injury induced EMT as characterized by downregulation of E-cadherin and upregulation of vimentin and Snail1 in a rat model of HN. This was coincident with epithelial cells arrested at the G2/M phase of cell cycle, activation of Notch1/Jagged-1 and Wnt/β-catenin signaling pathways, and upregulation of matrix metalloproteinase-2 (MMP-2) and MMP-9. Administration of U0126, a selective inhibitor of ERK1/2, blocked all these responses. U0126 was also effective in inhibiting renal tubular cell injury, as shown by decreased expression of lipocalin-2 and kidney injury molecule-1 and active forms of caspase-3. U0126 or ERK1/2 siRNA can inhibit tubular cell EMT and cell apoptosis as characterized with decreased expression of cleaved caspase-3. Moreover, ERK1/2 inhibition suppressed hyperuricemic injury-induced oxidative stress as indicated by decreased malondialdehyde and increased superoxide dismutase. Collectively, ERK1/2 inhibition-elicited renal protection is associated with inhibition of EMT through inactivation of multiple signaling pathways and matrix metalloproteinases, as well as attenuation of renal tubule injury by enhancing cellular resistance to oxidative stress.

New Rice-Derived Short Peptide Potently Alleviated Hyperuricemia Induced by Potassium Oxonate in Rats.

Gout that caused by hyperuricemia affects human health seriously and more efficient drugs are urgently required clinically. In this study, a novel peptide named RDP1 (AAAAGAKAR, 785.91 Da) was identified from the extract of shelled fruits of Oryza sativa. Our results demonstrated that RDP1 (the minimum effective concentration is 10 μg/kg) could significantly reduce the serum uric acid and creatinine and alleviate hyperuricemic nephropathy in rats by intragastric administration. RDP1 inhibited xanthine oxidase, which also was verified at the animal level. Results from molecular docking indicated that RDP1 can inhibit uric acid formation by occupying the binding site of xanthine oxidase to xanthine. Besides, RDP1 showed no toxicity on rats and was stable in several temperatures, demonstrating its advantages for transportation. This research was the first discovery of antihyperuricemic peptide from the shelled fruits of O. Sativa and provided a new candidate for the development of hypouricemic drugs.

Pterostilbene, a bioactive component of blueberries, alleviates renal fibrosis in a severe mouse model of hyperuricemic nephropathy

Accumulating evidences indicated that hyperuricemia was an independent risk factor for kidney diseases and contributed to kidney fibrosis. Preventing and treating renal fibrosis was an optimal treatment for hyperuricemia-induced kidney diseases. In the study, pterostilbene (PTE) as a bioactive component of blueberries was confirmed to possess lowering serum uric acid and renal protective functions by the decrease of serum creatinine, BUN, urine albumin, and urine albumin-to-creatinine ratio (uACR) in a mouse model of hyperuricemic nephropathy (HN). Importantly, PTE treatment remarkably alleviated renal fibrosis of HN mice indicated by the downregulation of fibronectin, collagen I and α-SMA production. Furthermore, PTE could suppress the fibrosis-related protein expressions of TGF-β1/Smad3, Src and STAT3 in the kidneys of HN mice. In conclusion, PTE suppressed the activation of TGF-β1/Smad3, Src and STAT3 signaling pathway to alleviate renal fibrosis of HN mice, highlighting that PTE was a potential antifibrotic strategy for hyperuricemic nephropathy.

Pharmacological inhibition of autophagy by 3-MA attenuates hyperuricemic nephropathy.

Autophagy has been identified as a cellular process of bulk degradation of cytoplasmic components and its persistent activation is critically involved in the renal damage induced by ureteral obstruction. However, the role and underlying mechanisms of autophagy in hyperuricemic nephropathy (HN) remain unknown. In the present study, we observed that inhibition of autophagy by 3-methyladenine (3-MA) abolished uric acid-induced differentiation of renal fibroblasts to myofibroblasts and activation of transforming growth factor-β1 (TGF-β1), epidermal growth factor receptor (EGFR), and Wnt signaling pathways in cultured renal interstitial fibroblasts. Treatment with 3-MA also abrogated the development of HN in vivo as evidenced by improving renal function, preserving renal tissue architecture, reducing the number of autophagic vacuoles, and decreasing microalbuminuria. Moreover, 3-MA was effective in attenuating renal deposition of extracellular matrix (ECM) proteins and expression of α-smooth muscle actin (α-SMA) and reducing renal epithelial cells arrested at the G2/M phase of cell cycle. Injury to the kidney resulted in increased expression of TGF-β1 and TGFβ receptor I, phosphorylation of Smad3 and TGF-β-activated kinase 1 (TAK1), and activation of multiple cell signaling pathways associated with renal fibrogenesis, including Wnt, Notch, EGFR, and nuclear factor-κB (NF-κB). 3-MA treatment remarkably inhibited all these responses. In addition, 3-MA effectively suppressed infiltration of macrophages and lymphocytes as well as release of multiple profibrogenic cytokines/chemokines in the injured kidney. Collectively, these findings indicate that hyperuricemia-induced autophagy is critically involved in the activation of renal fibroblasts and development of renal fibrosis and suggest that inhibition of autophagy may represent a potential therapeutic strategy for HN.

Risk factors analysis for hyperuricemic nephropathy among CKD stages 3–4 patients: an epidemiological study of hyperuricemia in CKD stages 3–4 patients in Ningbo, China

Objective: Uric acid (UA) is a risk marker of CKD and SUA level in CKD 3–4 patients closely correlates with hyperuricemic nephropathy (HN) morbidity. This study was designed to evaluate the risk factors for HN in CKD 3–4 patients. Methods: The 461 CKD 3–4 patients were recruited and all patients were divided into three groups (24 h UUA normal, underexeret, and overproduct type groups) according to the 24 h UUA level after receiving low purine food for five days. Clinical and biochemical characteristics of CKD patients were collected for the logistic regression analysis. Correlation analysis of the mRNA relative expression level of hUAT and hURAT1 with serum UA (SUA) level also was evaluated. Results: There were significant increases in characteristics including average age, waist-to-height ratio (WHR), SUA levels, HN ratio, TG/HDL ratio, body mass index (BMI), blood pressure (BP), uNgal/Cr. ratio, and uKim-1/Cr. ratio in overproduct type group in comparison with the other two groups. Logistic regression analysis showed SUA, CHO, uKim-1/Cr. ratio and uNgal/Cr. ratio were independent and multiple risk factors for HN. Moreover, hUAT and hURAT1 mRNA relative expression levels were significantly correlated with SUA level in the underexeret type CKD 3–4 patients. Conclusions: These results showed SUA and other characteristics contributed to HN morbidity in CKD 3–4 patients.

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Baicalein decreases uric acid and prevents hyperuricemic nephropathy in mice

Baicalein decreases uric acid and prevents hyperuricemic nephropathy in mice