EGF Receptor Inhibition Alleviates Hyperuricemic Nephropathy

Fasudil attenuates oxidative stress-induced partial epithelial-mesenchymal transition of tubular epithelial cells in hyperuricemic nephropathy via activating Nrf2

Anti-partial epithelial-mesenchymal transition (pEMT) treatment of renal tubular epithelial cells (TECs) represents a promising therapeutic approach. Hyperuricemia nephropathy (HN) arises as a consequence of hyperuricemia (HUA)-induced tubulointerstitial fibrosis (TIF). Studies have suggested that the Ras homolog member A (RhoA)/Rho-associated kinase (ROCK) pathway is a crucial signaling transduction system in renal fibrosis. Fasudil, a RhoA/ROCK inhibitor, has exhibited the potential to prevent fibrosis progress. However, its impact on the pEMT of TECs in HN remains unclear. Here, an HN rat model and an uric acid (UA)-stimulated human kidney 2 (HK2) cell model were established and treated with Fasudil to explore its effects. Furthermore, the underlying mechanism of action involved in the attenuation of pEMT in TECs by Fasudil during HN was probed by using multiple molecular approaches. The HN rat model exhibited significant renal dysfunction and histopathological damage, whereas in vitro and in vivo experiments further confirmed the pEMT status accompanied by RhoA/ROCK pathway activation and oxidative stress in tubular cells exposed to UA. Notably, Fasudil ameliorated these pathological changes, and this was consistent with the trend of ROCK silencing in vitro. Mechanistically, we identified the Neh2 domain of nuclear factor erythroid 2-related factor 2 (Nrf2) as a target of Fasudil for the first time. Fasudil targets Nrf2 activation and antagonizes oxidative stress to attenuate the pEMT of TECs in HN. Our findings suggest that Fasudil attenuates oxidative stress-induced pEMT of TECs in HN by targeting Nrf2 activation. Thus, Fasudil is a potential therapeutic agent for the treatment of HN.

Simiao pills alleviates renal injury associated with hyperuricemia: A multi-omics analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Simiao Pills, a classical traditional Chinese medicine prescription recorded in Cheng Fang Bian Du, has been traditionally used to treat hyperuricemia due to its heat-clearing and diuretic properties. Studies have shown that Simiao Pills effectively reduce uric acid levels. However, further research is needed to elucidate the precise composition of Simiao Pills for treating hyperuricemia and their potential pharmacological mechanism.

AIM OF THE STUDY

This study aimed to investigate the therapeutic effects of Simiao Pills on hyperuricemia, with a particular focus on evaluating their protective role against hyperuricemia-induced renal injury and elucidating the underlying mechanism of action.

MATERIALS AND METHODS

UPLC-MS/MS was used to identify the components of Simiao Pills. The hyperuricemia model mice were established by intraperitoneal injecting potassium oxonate (PO) and oral administrating hypoxanthine (HX). Network pharmacology, transcriptome, and metabolomics analyses were integrated to explore the mechanism of Simiao Pills in reducing uric acid and protecting the kidney. Mechanistic and functional studies were conducted to validate the potential mechanisms.

RESULTS

Simiao Pills were found to contain 12 characteristic components. Treatment with Simiao Pills significantly reduced serum uric acid levels and ameliorated hyperuricemia-induced renal injury. Simiao Pills inhibited the enzymatic activities of XOD and XDH, and regulated the uric acid transporters in the kidney and ileum. Transcriptome and network pharmacology analyses highlighted quercetin, berberine, kaempferol, and baicalein as the principal active components of Simiao Pills acting on the kidney during hyperuricemia treatment, primarily impacting fibrosis, apoptosis, and inflammation-related signaling pathways. Metabolomic analysis unveiled 21 differential metabolites and 5 metabolic pathways associated with Simiao Pills against renal injury associated with hyperuricemia. Further experimental results validated that Simiao Pills reduced renal fibrosis, apoptotic renal cells, serum inflammation levels, and inhibited the NF-κB/NLRP3/IL-1β signaling pathway.

CONCLUSION

This study demonstrated that Simiao Pills significantly reduced serum uric acid levels and improved renal injury by regulating inflammation, apoptosis, and renal fibrosis. These findings have provided a robust scientific pharmacological basis for the use of Simiao Pills in treating hyperuricemia patients.

Direct GPCR-EGFR interaction enables synergistic membrane-to-nucleus information transfer

We addressed the heteromerization of the epidermal growth factor receptor (EGFR) with G-protein coupled receptors (GPCR) on the basis of angiotensin-II-receptor-subtype-1(AT1R)-EGFR interaction as proof-of-concept and show its functional relevance during synergistic nuclear information transfer, beyond ligand-dependent EGFR transactivation. Following in silico modelling, we generated EGFR-interaction deficient AT1R-mutants and compared them to AT1R-wildtype. Receptor interaction was assessed by co-immunoprecipitation (CoIP), Förster resonance energy transfer (FRET) and fluorescence-lifetime imaging microscopy (FLIM). Changes in cell morphology, ERK1/2-phosphorylation (ppERK1/2), serum response factor (SRF)-activation and cFOS protein expression were determined by digital high content microscopy at the single cell level. FRET, FLIM and CoIP confirmed the physical interaction of AT1R-wildtype with EGFR that was strongly reduced for the AT1R-mutants. Responsiveness of cells transfected with AT1R-WT or -mutants to angiotensin II or EGF was similar regarding changes in cell circularity, ppERK1/2 (direct and by ligand-dependent EGFR-transactivation), cFOS-expression and SRF-activity. By contrast, the EGFR-AT1R-synergism regarding these parameters was completely absent for in the interaction-deficient AT1R mutants. The results show that AT1R-EGFR heteromerisation enables AT1R-EGFR-synergism on downstream gene expression regulation, modulating the intensity and the temporal pattern of nuclear AT1R/EGFR-information transfer. Furthermore, remote EGFR transactivation, via ligand release or cytosolic tyrosine kinases, is not sufficient for the complete synergistic control of gene expression.

Xanthoceras sorbifolium leaves alleviate hyperuricemic nephropathy by inhibiting the PI3K/AKT signaling pathway to regulate uric acid transport

ETHNOPHARMACOLOGICAL RELEVANCE

In China, Xanthoceras sorbifolium Bunge was first documented as "Wen Guan Hua" in the "Jiu Huang Ben Cao" in 1406 A.D. According to the "National Compilation of Chinese Herbal Medicine," X. sorbifolium leaves are sweet and flat in nature and can dispel wind and dampness, suggesting that their extract can be used to treat rheumatoid arthritis. X. sorbifolium Bunge has also been used to treat arteriosclerosis, hyperlipidemia, hypertension, chronic hepatitis, and rheumatism, complications associated with hyperuricemic nephropathy (HN), a condition characterized by kidney damage resulting from high levels of uric acid (UA) in the blood.

AIM OF THE STUDY

The purpose of this study was to investigate the effects and underlying mechanisms of a 70% ethanol extract from X. sorbifolium leaves (EX) in alleviating HN.

MATERIALS AND METHODS

A mouse model of hyperuricemia was established to initially evaluate the hypouricemic effects and determine the effective dose of EX. Phytochemical analyses were conducted using ultra high-performance liquid chromatography and liquid chromatography-mass spectroscopy. The potential key pathways of EX in the alleviation of HN were inferred using network pharmacology and bioinformatics. An HN rat model was then established, and experiments including biomarker detection, western blotting, reverse transcription quantitative polymerase chain reaction, immunohistochemical and Masson's trichrome staining, and transmission electron microscopy were conducted to evaluate the effect of EX on UA transporter expression in vitro.

RESULTS

Network pharmacology and bioinformatics analyses revealed that the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway was the key pathway for the alleviation of HN progression by EX. EX treatment reduced serum biomarkers in HN rats, downregulated the expression of p-PI3K, p-AKT, glucose transporter 9 (GLUT9), urate transporter 1 (URAT1), Collagen I, matrix metalloproteinase (MMP)-2, and MMP-9, and upregulated the expression of ATP binding cassette subfamily G member 2 (ABCG2) to improve renal interstitial fibrosis in HN rats. A high content of both quercitrin and cynaroside were identified in EX; their administration inhibited the increased expression of GLUT9 and URAT1 in damaged HK-2 cells.

CONCLUSION

Our study provides evidence that EX alleviates HN. The potential mechanism underlying this effect may be the regulation of UA transporters, such as GLUT9 and URAT1, by limiting the activation of the PI3K/AKT signaling pathway to improve renal injury.

Mechanisms of norcantharidin against renal tubulointerstitial fibrosis

Renal tubulointerstitial fibrosis (RTIF) is a common feature and inevitable consequence of all progressive chronic kidney diseases, leading to end-stage renal failure regardless of the initial cause. Although research over the past few decades has greatly improved our understanding of the pathophysiology of RTIF, until now there has been no specific treatment available that can halt the progression of RTIF. Norcantharidin (NCTD) is a demethylated analogue of cantharidin, a natural compound isolated from 1500 species of medicinal insect, the blister beetle (Mylabris phalerata Pallas), traditionally used for medicinal purposes. Many studies have found that NCTD can attenuate RTIF and has the potential to be an anti-RTIF drug. This article reviews the recent progress of NCTD in the treatment of RTIF, with emphasis on the pharmacological mechanism of NCTD against RTIF.

Pharmacological inhibition of Src family kinases attenuates hyperuricemic nephropathy

Hyperuricemia is an independent risk factor for chronic kidney disease and contributes to renal fibrosis. This study aims to investigate the effect of Src family kinase (SFK) inhibition on the development of hyperuricemic nephropathy (HN) and the mechanisms involved. In a rat model of HN, feeding rats a mixture of adenine and potassium oxonate increased Src phosphorylation, severe glomerular sclerosis, and renal interstitial fibrosis, accompanied by renal dysfunction and increased urine microalbumin excretion. Administration of PP1, a highly selective SFK inhibitor, prevented renal dysfunction, reduced urine microalbumin, and inhibited activation of renal interstitial fibroblasts and expression of extracellular proteins. PP1 treatment also inhibited hyperuricemia-induced activation of the TGF-β1/Smad3, STAT3, ERK1/2, and NF-κB signaling pathways and expression of multiple profibrogenic cytokines/chemokines in the kidney. Furthermore, PP1 treatment significantly reduced serum uric acid levels and xanthine oxidase activity. Thus, blocking Src can attenuate development of HN via a mechanism associated with the suppression of TGF-β1 signaling, inflammation, and uric acid production. The results suggest that Src inhibition might be a promising therapeutic strategy for HN.

Caspase-11/GSDMD contributes to the progression of hyperuricemic nephropathy by promoting NETs formation

Hyperuricemia is an independent risk factor for chronic kidney disease (CKD) and promotes renal fibrosis, but the underlying mechanism remains largely unknown. Unresolved inflammation is strongly associated with renal fibrosis and is a well-known significant contributor to the progression of CKD, including hyperuricemia nephropathy. In the current study, we elucidated the impact of Caspase-11/Gasdermin D (GSDMD)-dependent neutrophil extracellular traps (NETs) on progressive hyperuricemic nephropathy. We found that the Caspase-11/GSDMD signaling were markedly activated in the kidneys of hyperuricemic nephropathy. Deletion of Gsdmd or Caspase-11 protects against the progression of hyperuricemic nephropathy by reducing kidney inflammation, proinflammatory and profibrogenic factors expression, NETs generation, α-smooth muscle actin expression, and fibrosis. Furthermore, specific deletion of Gsdmd or Caspase-11 in hematopoietic cells showed a protective effect on renal fibrosis in hyperuricemic nephropathy. Additionally, in vitro studies unveiled the capability of uric acid in inducing Caspase-11/GSDMD-dependent NETs formation, consequently enhancing α-smooth muscle actin production in macrophages. In summary, this study demonstrated the contributory role of Caspase-11/GSDMD in the progression of hyperuricemic nephropathy by promoting NETs formation, which may shed new light on the therapeutic approach to treating and reversing hyperuricemic nephropathy.

Anti-Hyperuricemic Effects of Extracts from Chaenomeles speciosa (Sweet) Nakai Fruits on Hyperuricemic Rats

Chaenomeles speciosa (Sweet) Nakai (C. speciosa) fruit has medicinal and food applications and exhibits beneficial pharmacological properties. This study aimed to explore the hypouricemic effect of C. speciosa fruit extracts on hyperuricemic rats and uncover potential protective mechanisms. The rats were given hypoxanthine (HX, 100 mg/kg) and potassium oxonate (PO, 300 mg/kg) for 14 days to induce hyperuricemia. Subsequently, the rats were orally administered C. speciosa fruits total extract (CSFTE, 250, 500, and 1000 mg/kg) and allopurinol (AP, 10 mg/kg) one hour after exposure to HX and PO. The results showed that CSFTE had significant xanthine oxidase (XOD) inhibitory activity in vitro (IC50 value of 334.2 μg/mL) and exhibited hypouricemic effects in vivo, reducing uric acid (UA), creatinine (CRE), and blood urea nitrogen (BUN) levels in serum. CSFTE increased UA excretion through the regulation of URAT1, GLUT9, OAT1, and OAT3 protein expression in the kidneys of hyperuricemic rats. Additionally, CSFTE (500 and 1000 mg/kg) was more effective than AP in improving renal injury and protecting kidney function in hyperuricemic rats. Our study demonstrated that CSFTE effectively reduced UA levels and protected the kidneys by inhibiting XOD expression in vitro and regulating UA, CRE, BUN, URAT1, GLUT9, OAT1, and OAT3 proteins in vivo.

SLC2A9 rs16890979 reduces uric acid absorption by kidney organoids

Introduction: The excretion and absorption of uric acid (UA) by the kidneys helps regulate serum UA levels. GLUT9, encoded by SLC2A9, is mainly expressed in the renal tubules responsible for UA absorption. SLC2A9 polymorphisms are associated with different serum UA levels. However, the lack of proper in vitro models has stalled research on the mechanisms of single nucleotide polymorphisms (SNPs) that affect UA metabolism in human urate transporters. Methods: In this study, we constructed a gene-edited human embryonic stem cells-9 (ESC-H9) derived kidney organoid bearing rs16890979, an SLC2A9 missense mutation with undetermined associations with hyperuricemia or hypouricemia. Kidney organoids derived from ESC-H9 with genetical overexpression (OE) and low expression (shRNA) of SLC2A9 to serve as controls to study the function of SLC2A9. The function of rs16890979 on UA metabolism was evaluated after placing the organoids to urate-containing medium and following histopathological analysis. Results: The kidney organoids with heterozygous or homozygous rs16890979 mutations showed normal SLC2A9 expression levels and histological distribution, phenotypically similar to the wild-type controls. However, reduced absorption of UA by the kidney organoids with rs16890979 mutants was observed. This finding together with the observation that UA absorption is increased in organoids with SLC2A9 overexpression and decreased in those with SLC2A9 knockdown, suggest that GLUT9 is responsible for UA absorption, and the rs16890979 SNP may compromise this functionality. Moreover, epithelial-mesenchymal transition (EMT) was detected in organoids after UA treatment, especially in the kidney organoid carrying GLUT9OE, suggesting the cytobiological mechanism explaining the pathological features in hyperuricosuria-related renal injury. Discussion: This study showing the transitional value of kidney organoid modeling the function of SNPs on UA metabolism. With a defined genetic background and a confirmed UA absorption function should be useful for studies on renal histological, cellular, and molecular mechanisms with this organoid model.

Fisetin ameliorates fibrotic kidney disease in mice via inhibiting ACSL4-mediated tubular ferroptosis

Kidney fibrosis is the hallmark of chronic kidney disease (CKD) progression, whereas no effective anti-fibrotic therapies exist. Recent evidence has shown that tubular ferroptosis contributes to the pathogenesis of CKD with persistent proinflammatory and profibrotic responses. We previously reported that natural flavonol fisetin alleviated septic acute kidney injury and protected against hyperuricemic nephropathy in mice. In this study, we investigated the therapeutic effects of fisetin against fibrotic kidney disease and the underlying mechanisms. We established adenine diet-induced and unilateral ureteral obstruction (UUO)-induced CKD models in adult male mice. The two types of mice were administered fisetin (50 or 100 mg·kg-1·d-1, i.g.) for 3 weeks or 7 days, respectively. At the end of the experiments, the mice were euthanized, and blood and kidneys were gathered for analyzes. We showed that fisetin administration significantly ameliorated tubular injury, inflammation, and tubulointerstitial fibrosis in the two types of CKD mice. In mouse renal tubular epithelial (TCMK-1) cells, treatment with fisetin (20 μM) significantly suppressed adenine- or TGF-β1-induced inflammatory responses and fibrogenesis, and improved cell viability. By quantitative real-time PCR analysis of ferroptosis-related genes, we demonstrated that fisetin treatment inhibited ferroptosis in the kidneys of CKD mice as well as in injured TCMK-1 cells, as evidenced by decreased ACSL4, COX2, and HMGB1, and increased GPX4. Fisetin treatment effectively restored ultrastructural abnormalities of mitochondrial morphology and restored the elevated iron, the reduced GSH and GSH/GSSG as well as the increased lipid peroxide MDA in the kidneys of CKD mice. Notably, abnormally high expression of the ferroptosis key marker ACSL4 was verified in the renal tubules of CKD patients (IgAN, MN, FSGS, LN, and DN) as well as adenine- or UUO-induced CKD mice, and in injured TCMK-1 cells. In adenine- and TGF-β1-treated TCMK-1 cells, ACSL4 knockdown inhibited tubular ferroptosis, while ACSL4 overexpression blocked the anti-ferroptotic effect of fisetin and reversed the cytoprotective, anti-inflammatory, and anti-fibrotic effects of fisetin. In summary, we reveal a novel aspect of the nephroprotective effect of fisetin, i.e. inhibiting ACSL4-mediated tubular ferroptosis against fibrotic kidney diseases.

GRP/GRPR signaling pathway aggravates hyperuricemia-induced renal inflammation and fibrosis via ABCG2-dependent mechanisms

The gastrin-releasing peptide receptor (GRPR) binds to ligands such as gastrin-releasing peptide (GRP) and plays a variety of biological roles. In this study, we investigated the therapeutic effect of a novel gastrin-releasing peptide receptor antagonist RH-1402 in hyperuricemia-induced kidney fibrosis and its underlying mechanisms. We conducted enzyme linked immunosorbent assay (ELISA) and immunohistochemical analyses and found that proGRP and GRPR expression levels were significantly increased in patients with hyperuricemic nephropathy (HN) and HN mice. GRPR knockdown significantly attenuated inflammatory and fibrotic responses in adenosine-treated human proximal tubule epithelial cells. GRPR knockout or GRPR conditional knockout in renal tubular epithelial cells significantly alleviated the decline in renal function and fibrosis in HN mice in vivo. RNA-seq and String database analysis revealed that GRP/GRPR promoted HN by suppressing the ABCG2/PDZK1 and increasing TGF-β/Smad3 levels by activating the NF-κB pathway. Overexpression of GRPR increased TGF-β/Smad3 levels, where as it reduced ABCG2/PDZK1 levels in adenosine-treated HK2 cells, which was reversed by the NF-κB inhibitor. Furthermore, we evaluated the therapeutic effects of the novel GRPR inhibitor RH-1402 on hyperuricaemia-induced renal injury and evaluated the inflammatory and fibrosis responses in vivo and in vitro. Pre-treatment with RH-1402 attenuated hyperuricaemia-induced renal injury, restored renal function, and suppressed renal inflammation and fibrosis. Taken together, GRPR enhances hyperuricaemia-induced tubular injury, inflammation, and renal fibrosis via ABCG2-dependent mechanisms and may serve as a promising therapeutic target for HN treatment.

Coffee Leaf Tea Extracts Improve Hyperuricemia Nephropathy and Its Associated Negative Effect in Gut Microbiota and Amino Acid Metabolism in Rats

Hyperuricemia nephropathy (HN) is a metabolic disease characterized by tubular damage, tubulointerstitial fibrosis, and uric acid kidney stones and has been demonstrated to be associated with hyperuricemia. Coffee leaf tea is drunk as a functional beverage. However, its prevention effects on HN remain to be explored. This study showed that coffee leaf tea extracts (TE) contain 19 polyphenols, with a total content of 550.15 ± 27.58 mg GAE/g. TE decreased serum uric acid levels via inhibiting XOD activities and modulating the expression of urate transporters (GLUT9, OAT3, and ABCG2) in HN rats. TE prevented HN-induced liver and kidney damage and attenuated renal fibrosis. Moreover, it upregulated the abundance of SCFA-producing bacteria (Phascolarctobacterium, Alloprevotella, and Butyricicoccus) in the gut and reversed the amino acid-related metabolism disorder caused by HN. TE also decreased the circulating LPS and d-lactate levels and increased the fecal SCFA levels. This study supported the preliminary and indicative effect of coffee leaf tea in the prevention of hyperuricemia and HN.

Coptisine, the Characteristic Constituent from Coptis chinensis, Exhibits Significant Therapeutic Potential in Treating Cancers, Metabolic and Inflammatory Diseases

Naturally derived alkaloids belong to a class of quite significant organic compounds. Coptisine, a benzyl tetrahydroisoquinoline alkaloid, is one of the major bioactive constituents in Coptis chinensis Franch., which is a famous traditional Chinese medicine. C. chinensis possesses many kinds of functions, including the ability to eliminate heat, expel dampness, purge fire, and remove noxious substances. In Asian countries, C. chinensis is traditionally employed to treat carbuncle and furuncle, diabetes, jaundice, stomach and intestinal disorders, red eyes, toothache, and skin disorders. Up to now, there has been plenty of research of coptisine with respect to its pharmacology. Nevertheless, a comprehensive review of coptisine-associated research is urgently needed. This paper was designed to summarize in detail the progress in the research of the pharmacology, pharmacokinetics, safety, and formulation of coptisine. The related studies included in this paper were retrieved from the following academic databases: The Web of Science, PubMed, Google scholar, Elsevier, and CNKI. The cutoff date was January 2023. Coptisine manifests various pharmacological actions, including anticancer, antimetabolic disease, anti-inflammatory disease, and antigastrointestinal disease effects, among others. Based on its pharmacokinetics, the primary metabolic site of coptisine is the liver. Coptisine is poorly absorbed in the gastrointestinal system, and most of it is expelled in the form of its prototype through feces. Regarding safety, coptisine displayed potential hepatotoxicity. Some novel formulations, including the [Formula: see text]-cyclodextrin-based inclusion complex and nanocarriers, could effectively enhance the bioavailability of coptisine. The traditional use of C. chinensis is closely connected with the pharmacological actions of coptisine. Although there are some disadvantages, including poor solubility, low bioavailability, and possible hepatotoxicity, coptisine is still a prospective naturally derived drug candidate, especially in the treatment of tumors as well as metabolic and inflammatory diseases. Further investigation of coptisine is necessary to facilitate the application of coptisine-based drugs in clinical practice.

The effect of lipid metabolism disorder on patients with hyperuricemia using Multi-Omics analysis

A multiomics study was conducted to investigate how lipid metabolism disorders affect the immune system in Xinjiang patients with hyperuricemia. The serum of 60 healthy individuals and 60 patients with hyperuricemia was collected. This study used LC-MS and HPLC to analyze differential lipid metabolites and enrichment pathways. It measured levels of immune factors tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), carnitine palmitoyltransferase-1 (CPT1), transforming growth factor-β1 (TGF-β1), glucose (Glu), lactic acid (LD), interleukin 10 (IL-10), and selenoprotein 1 (SEP1) using ELISA, as well as to confirm dysregulation of lipid metabolism in hyperuricemia. 33 differential lipid metabolites were significantly upregulated in patients with hyperuricemia. These lipid metabolites were involved in arachidonic acid metabolism, glycerophospholipid metabolism, linoleic acid metabolism, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, and alpha-Linolenic acid metabolism pathways. Moreover, IL-10, CPT1, IL-6, SEP1, TGF-β1, Glu, TNF-α, and LD were associated with glycerophospholipid metabolism. In patients with hyperuricemia of Han and Uyghur nationalities, along with healthy individuals, significant differences in CPT1, TGF-β1, Glu, and LD were demonstrated by ELISA (P < 0.05). Furthermore, the levels of SEP1, IL-6, TGF-β1, Glu, and LD differed considerably between groups of the same ethnicity (P < 0.05). It was found that 33 kinds of lipid metabolites were significantly different in patients with hyperuricemia, which mainly involved 5 metabolic pathways. According to the results of further studies, it is speculated that CPT1, TGF-β1, SEP1, IL-6, Glu and LD may increase fatty acid oxidation and mitochondrial oxidative phosphorylation in patients through glycerophospholipid pathway, reduce the rate of glycolysis, and other pathways to change metabolic patterns, promote different cellular functions, and thus affect the disease progression in patients with hyperuricemia.

Chloroquine inhibits NLRP3 inflammasomes activation and alleviates renal fibrosis in mouse model of hyperuricemic nephropathy with aggravation by a high-fat-diet

Numerous epidemiological studies have demonstrated that hyperuricemia (HUA) is a risk factor for renal diseases and renal fibrosis. Dietary patterns can influence serum urate levels and hyperuricemic nephropathy (HN). NLRP3 inflammasomes play a crucial role in various inflammatory responses and contribute to HN progression. Chloroquine (CQ) is an anti-inflammatory and disease-modifying anti-rheumatic drug (DMARD) utilized in treating autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. In this study, we examined the effects and underlying mechanisms of CQ in a high-fat-diet (HFD) exacerbated mouse model of HN. C57BL/6 mice were randomized into either a control group or an HN group (induced by adenine/potassium oxonate treatment), followed by a normal diet or HFD, with or without CQ treatment. Our findings revealed that the HN group exhibited elevated serum levels of blood urea nitrogen (BUN) and creatinine compared to the control group. Additionally, the HN + HFD group displayed increased serum levels of uric acid, BUN, and creatinine relative to the control + HFD group. Moreover, the HFD exacerbated renal uric acid crystal deposition and fibrosis in HN mice compared to a normal diet. CQ ameliorated renal dysfunction, as evidenced by reduced serum creatinine levels, renal fibrosis, and renal tubular injury scores, and significantly decreased NLRP3, ASC, caspase-1, and IL-1β levels in HN mice. These findings suggest that CQ inhibits the activation of NLRP3 inflammasomes and may serve as a potential therapeutic strategy for HN treatment.

Qinling liquid ameliorates renal immune inflammatory damage via activating autophagy through AMPK/Stat3 pathway in uric acid nephropathy

BACKGROUND

Excessive deposition of uric acid (UA) is one of the risk factors for kidney damage. Qinling liquid (QL) has a certain therapeutic effect on uric acid nephropathy (UAN), but its regulation mechanism is still unclear.

METHODS

UAN rat models and UA induced rat renal tubular epithelial cells (NRK-52E) were constructed to evaluate the functional roles of QL. We firstly evaluated the kidney function and the degree of kidney damage in rats after QL treatment. Then, effects of QL on autophagy and NLRP3 inflammasome activation were assessed. Moreover, the regulation of QL in AMPK and Stat3 phosphorylation levels and the relationship among autophagy, AMPK/Stat3 pathway and NLRP3 inflammasomes were determined.

RESULTS

QL could alleviate the inflammatory damage in UAN rats and promote the activation of autophagy. In addition, QL suppressed UA-induced activation of NLRP3 inflammasomes in rat renal tubular epithelial cells, which was partially reversed by autophagy inhibitor. Further, AMPK/Stat3 axis-mediated autophagy participated in the regulation of UA-induced NLRP3 inflammasome activation in NRK-52E cells. Finally, we confirmed that inhibiting AMPK/Stat3 pathway partly deteriorated the ameliorating effect of QL on renal immune inflammatory injury in UAN rats.

CONCLUSION

Through in vivo and in vitro experiments, we found that QL promotes autophagy by activating the AMPK/Stat3 pathway, thereby improving renal immune inflammatory injury in UAN.

Ubiquitin-specific protease 11 promotes partial epithelial-to-mesenchymal transition by deubiquitinating the epidermal growth factor receptor during kidney fibrosis

The aberrant expression of ubiquitin-specific protease 11 (USP11) is believed to be related to tumor progression. However, few studies have reported the biological function and clinical importance of USP11 in kidney fibrosis. Here, we demonstrated USP11 was highly upregulated in the kidneys from patients with chronic kidney disease and correlated positively with fibrotic lesion but negatively with kidney function. Conditional USP11 deletion or pharmacologic inhibition with Mitoxantrone attenuated pathological lesions and improved kidney function in both hyperuricemic nephropathy (HN)- and folic acid (FA)-induced mouse models of kidney fibrosis. Mechanistically, by RNA sequencing, USP11 was found to be involved in nuclear gene transcription of the epidermal growth factor receptor (EGFR). USP11 co-immunoprecipitated and co-stained with extra-nuclear EGFR and deubiquitinated and protected EGFR from proteasome-dependent degradation. Genetic or pharmacological depletion of USP11 facilitated EGFR degradation and abated augmentation of TGF-β1 and downstream signaling. This consequently alleviated the partial epithelial-mesenchymal transition, G2/M arrest and aberrant secretome of profibrogenic and proinflammatory factors in uric acid-stimulated tubular epithelial cells. Moreover, USP11 deletion had anti-fibrotic and anti-inflammatory kidney effects in the murine HN and FA models. Thus, our study provides evidence supporting USP11 as a promising target for minimizing kidney fibrosis and that inhibition of USP11 has potential to be an effective strategy for patients with chronic kidney disease.

Mechanism of Xiezhuo Huayu Yiqi Tongluo Formula in the Treatment of Uric Acid Nephropathy Based on Network Pharmacology, Molecular Docking, and In Vivo Experiments

Background

Xiezhuo Huayu Yiqi Tongluo Formula (XHYTF) consists of 14 Chinese herbal medicines. In this study, we investigated the potential mechanism of XHYTF in the treatment of uric acid nephropathy (UAN) through network pharmacology, molecular docking, and in vivo methods.

Methods

Using various pharmacological databases and analysis platforms, information on the active ingredients and targets of Chinese herbal medicine was collected, and UAN disease targets were retrieved using OMIM, Gene Cards, and NCBI. Then common target proteins were integrated. A Drug-Component-Target (D-C-T) map was constructed to screen core compounds and build a protein-protein interaction (PPI) network. Further, Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed for common targets, and a Drug-Component-Target-Pathway (D-C-T-P) network diagram was constructed. The molecular docking simulation was performed to verify the binding affinity between core components and hub targets. Subsequently, the UAN rat model was established, followed by the collection of serum and renal tissues. The expression levels of indicators in the serum were determined using an enzyme-linked immunosorbent assay. The pathological changes of renal tissues were detected using H & E staining and Masson staining. The expression of related proteins in renal tissue was detected by western blot.

Results

In the study, 216 active ingredients and 439 targets in XHYTF were screened, and 868 targets were identified as being related to UAN. Among them, 115 were common targets. Based on the D-C-T network, quercetin, luteolin, β-sitosterol, and stigmasterol were observed to be the key active ingredients of XHYTF that were effective against UAN. The analysis of the PPI network revealed TNF, IL6, AKT1, PPARG, and IL1β as the 5 key targets. GO enrichment analysis revealed that the pathways were mainly concentrated in cell killing, regulation of signaling receptor activity, and other activities. Subsequently, KEGG pathway analysis revealed that multiple signaling pathways, including the HIF-1, PI3K-Akt, IL-17, and other signaling pathways, were closely related to the action of XHYTF. All 5 key targets were confirmed to interact with all core active ingredients. In vivo experiments indicated that XHYTF significantly reduced blood uric acid and creatinine levels, alleviated inflammatory cell infiltration in kidney tissues, reduced the levels of serum inflammatory factors such as TNF-α and IL1β, and ameliorated renal fibrosis in rats with UAN. Finally, western blot revealed decreased levels of PI3K and AKT1 proteins in the kidney, which confirmed the hypothesis.

Conclusion

Collectively, our observations demonstrated that XHYTF significantly protects kidney function, including alleviation of inflammation and renal fibrosis via multiple pathways. This study provided novel insights into the treatment of UAN using traditional Chinese medicines.

Therapeutic effects of traditional Chinese medicine on gouty nephropathy: Based on NF-κB signalingpathways

As the final product of purine metabolism, excess serum uric acid (SUA) aggravates the process of some metabolic diseases. SUA causes renal tubule damage, interstitial fibrosis, and glomerular hardening, leading to gouty nephropathy (GN). A growing number of investigations have shown that NF-κB mediated inflammation and oxidative stress have been directly involved in the pathogenesis of GN. Traditional Chinese medicine's treatment methods of GN have amassed a wealth of treatment experience. In this review, we first describe the mechanism of NF-κB signaling pathways in GN. Subsequently, we highlight traditional Chinese medicine that can treat GN through NF-κB pathways. Finally, commenting on promising candidate targets of herbal medicine for GN treatment via suppressing NF-κB signaling pathways was summarized.

Emodin ameliorates renal injury and fibrosis via regulating the miR-490-3p/HMGA2 axis

Renal fibrosis is a major pathological feature of chronic kidney disease (CKD). While emodin is reported to elicit anti-fibrotic effects on renal injury, little is known about its effects on microRNA (miRNA)-modulated mechanisms in renal fibrosis. In this study, we established a unilateral ureteral obstruction (UUO) model and a transforming growth factor (TGF)-β1-induced normal rat renal tubular epithelial cell line (NRK-52E) model to investigate the protective effects of emodin on renal fibrosis and its miRNA/target gene mechanisms. Dual-luciferase assay was performed to confirm the direct binding of miRNA and target genes in HEK293 cells. Results showed that oral administration of emodin significantly ameliorated the loss of body weight and the increase in physicochemical parameters, including serum uric acid, creatinine, and urea nitrogen in UUO mice. Inflammatory cytokines, including tumor necrosis factor-α, monocyte chemoattractant protein-1, and interleukin (IL)-1β, but not IL-6, were down-regulated by emodin administration. Emodin decreased the expression levels of TGF-β1 and fibrotic-related proteins, including alpha-smooth muscle actin, Collagen IV, and Fibronectin, and increased the expression of E-cadherin. Furthermore, miR-490-3p was decreased in UUO mice and negatively correlated with increased expression of high migration protein A2 (HMGA2). We further confirmed HMGA2 was the target of miR-490-3p. Transfection of miR-490-3p mimics decreased, while transfection of miR-490-3p inhibitors increased fibrotic-related proteins and HMGA2 expression levels in TGF-β1-induced NRK-52E cells. Furthermore, transfection of miR-490-3p mimics enhanced the anti-fibrotic effects of emodin, while transfection of miR-490-3p inhibitors abolished the protective effects of emodin. Thus, as a novel target of emodin that prevents renal fibrosis in the HMGA2-dependent signaling pathway, miR-490-3p has potential implications in CKD pathology.

Interaction of Harmful Alcohol Use and Tea Consumption on Hyperuricemia Among Han Residents Aged 30-79 in Chongqing, China

Objective

The prevalence of hyperuricemia appears to be high worldwide. We aimed to explore the interaction between harmful alcohol use and tea consumption on hyperuricemia.

Methods

This study recruited 22,449 Han residents based on the data from the China Multi-Ethnic Cohort (CMEC) study, Chongqing province, to have a face-to-face electronic questionnaire, physical examination, and clinical laboratory tests. The difference in hyperuricemia between the different populations was compared by the Chi-square test. The interaction between harmful alcohol use and tea consumption was analyzed by the multivariate logistic regression model.

Results

Amongst 22,449 participants, the mean age was 51.5±11.8 years, and 46.83% of them were males. The proportion of harmful alcohol use, tea consumption, and harmful alcohol use and tea consumption were 14.01%, 21.01%, and 6.54%, respectively. Multivariate logistic regression showed that the odds ratio (OR) of harmful alcohol use and tea consumption (OR=2.21, 95% CI: 1.58-3.10) was greater than that of harmful alcohol use (OR=1.63, 95% CI:1.17-2.27) and tea consumption (OR=1.34, 95% CI:1.10-1.63). Among males, the results were similar (harmful alcohol use and tea consumption: OR=2.02, 95% CI: 1.43-2.84; harmful alcohol use: OR=1.61, 95% CI: 1.14-2.27; tea consumption: OR=1.28, 95% CI: 1.05-1.57). However, among females, the odds ratio of harmful alcohol use and tea consumption (OR=15.50, 95% CI: 1.36-176.50) was more than 10 times than that of only harmful alcohol use (OR=1.55, 95% CI: 0.42-5.69) or tea consumption (OR=1.22, 95% CI: 0.52-2.82).

Conclusion

The interaction of harmful alcohol use and tea consumption was a positive risk for hyperuricemia in Han residents aged 30-79 years in China.

Lipidomics analysis facilitate insight into the molecular mechanisms of urate nephropathy in a gout model induced by combination of MSU crystals injection and high-fat diet feeding

Renal injury is one of the most common clinical manifestations of patients with hyperuricaemia/gout. The precise pathophysiological mechanism(s) for the renal injury is still unknown. Furthermore, it is also unclear whether the clinical therapies (e.g., colchicine and febuxostat) could prevent its progression or not. Lipids are involved in almost all of important biological processes and play critical roles in maintaining the renal functions. Herein, shotgun lipidomics was performed for class-targeted lipid analysis of cellular lipidomes in renal tissue of a gouty model induced by combination of monosodium urate crystals injection and high-fat diet feeding with/without treatment with either colchicine or febuxostat. Serum uric acid (UA), proinflammatory cytokines (i.e., TNF-α and IL-6), xanthine oxidase activity, footpad swelling, and pain threshold were determined to evaluate the gouty severity. Renal histopathological changes, blood urea nitrogen, creatinine, and kidney index were used to reflect renal injury. Lipidomics analysis revealed that altered triacylglycerol (TAG) profile, impaired mitochondrial function resulted by decreased tetra 18:2 cardiolipin, reduced 4-hydroxyalkenal (HNE) species, and elevated lysophospholipids were already present in the kidneys at early stage of renal injury, probably contributing to its occurrence and development. In addition to significantly reduce the UA level and relief the gouty severity, treatment with either colchicine or febuxostat could restore HNE bioavailability, thereby delaying the progression of renal injury. However, both of them could not recover the altered TAG profile and the impaired mitochondrial function, indicating that treatment with either of them could not completely prevent the development of renal injury in the gouty model.

Fibroblast Growth Factor 21 Attenuates the Progression of Hyperuricemic Nephropathy through Inhibiting Inflammation, Fibrosis and Oxidative stress

Elevated levels of circulating fibroblast growth factor 21 (FGF21) have been reported in patients with hyperuricemia. However, the effect of FGF21 in hyperuricemic nephropathy (HN) remains unexplored. Here, we investigated the effect and mechanism of action of FGF21 on HN. HN model was induced with adenine and potassium oxysalt in wild-type C57BL/6 mice and FGF21^-/- mice. For in vitro studies, human renal tubular epithelial (HK-2) cells were exposed to uric acid with/without FGF21 or β-Klotho-siRNA. Here, we reported aggravated renal dysfunction and structural damage in the FGF21^-/- mice compared to the wild-type mice. These were evident in the upsurge of inflammatory factors IL-1β, TNF-α, IL-6 and IL-18, fibrotic markers Collagen I and α-SMA, and oxidation products ROS and MDA. However, exogenous administration of FGF21 to wild-type HN mice significantly reversed these negative effects. In terms of mechanism, FGF21 significantly inhibited NF-κB/NLRP3 and TGF-β1/Smad3 pathways and promoted nuclear translocation of Nrf2 both in vivo and in vitro. Furthermore, the silencing of β-Klotho was marked by the attenuation of the improved effect of FGF21 on cell damage. In conclusion, our studies revealed that exogenous FGF21 treatment significantly improved HN, which was achieved by the inhibition of inflammation, fibrosis and oxidative stress.

lncRNA TUG1 regulates hyperuricemia-induced renal fibrosis in a rat model

Renal fibrosis is most common among chronic kidney diseases. Molecular studies have shown that long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) participate in renal fibrosis, while the roles of lncRNA taurine upregulated gene 1 (TUG1) and miR-140-3p in hyperuricemia-induced renal fibrosis remain less investigated. In this study, a rat hyperuricemia model is constructed by oral administration of adenine. TUG1, miR-140-3p, and cathepsin D (CtsD) expression levels in rat models are measured. After altering TUG1, miR-140-3p, or CtsD expression in modelled rats, biochemical indices, including uric acid (UA), serum creatine (SCr), blood urea nitrogen (BUN), and 24-h urine protein are detected, pathological changes in the renal tissues, and renal fibrosis are examined. In renal tissues from hyperuricemic rats, TUG1 and CtsD are upregulated, while miR-140-3p is downregulated. Inhibiting TUG1 or CtsD or upregulating miR-140-3p relieves renal fibrosis in hyperuricemic rats. Downregulated miR-140-3p reverses the therapeutic effect of TUG1 reduction, while overexpression of CtsD abolishes the role of miR-140-3p upregulation in renal fibrosis. Collectively, this study highlights that TUG1 inhibition upregulates miR-140-3p to ameliorate renal fibrosis in hyperuricemic rats by inhibiting CtsD.

Chlorogenic Acid Prevents Hyperuricemia Nephropathy via Regulating TMAO-Related Gut Microbes and Inhibiting the PI3K/AKT/mTOR Pathway

Hyperuricemia is an independent hazard factor of renal injury and can induce renal fibrosis, promoting the development of chronic kidney disease (CKD). This study aimed to explore the probability of chlorogenic acid (CGA) as a potential substance for preventing hyperuricemia nephropathy (HN). Pretreatment with CGA downregulated SUA, BUN, and CR levels, relieved oxidative stress and inflammatory response, alleviated kidney fibrosis, and contributed to the prevention of HN. In the gut microbiota, Blautia, Enterococcus, and Faecalibaculum related to trimethylamine N-oxide (TMAO) synthesis were significantly increased in HN rats. In addition, it showed a significant increase in serum TMAO content in HN rats. However, CGA regulated the cascade response of the microbiota-TMAO signaling to reverse the increase of serum TMAO. CGA also decreased the protein expression of protein kinase B (AKT) phosphorylation, phosphatidylinositide 3-kinase (PI3K), and mammalian target of rapamycin (mTOR) by reducing the production of TMAO. CGA delayed kidney fibrosis in HN rats as evidenced by regulating the cascade response of the microbiota-TMAO-PI3K/AKT/mTOR signaling pathway. In summary, CGA can be an excellent candidate for HN prevention.

Beneficial herb-drug interaction of Gnaphalium affine extract on benzbromarone: A pharmacokinetic and pharmacodynamic study in rats

BACKGROUND

Gnaphalium affine D. Don extract (GAD) enhanced efficacy and reduced toxicity of benzbromarone (BBR) in combination use. However, little is known about effects of GAD on the pharmacokinetics (PKs) and metabolic enzymes of BBR.

PURPOSE

To investigate the pharmacokinetic (PK) and pharmacodynamic (PD) mechanism of the herb-drug interactions (HDIs) between GAD and BBR.

STUDY DESIGN AND METHODS

Intragastric single BBR (4.5 or 50 mg/kg), single BBR (4.5 or 50 mg/kg) + single GAD (450 mg/kg, 2 h after BBR-administration), or single BBR (4.5 or 50 mg/kg) + multiple GAD (450 mg/kg/day, once daily for 7 days) were administered to both sexes for BBR PK studies in normal rats. Intragastric multiple BBR (4.5 mg/kg/day), or multiple BBR (4.5 mg/kg/day) + multiple GAD (450 mg/kg/day, 2 h after BBR-administration) were administered for BBR PK and PD studies in male rats with hyperuricemic nephropathy (HN). The cumulative anti-hyperuricemic effects of BBR and BBR+GAD were determined by plasma uric acid (UA) concentration-time curve and area under curve (AUC_UA). An in vivo cocktail approach was employed to determine the effects of GAD on cytochrome P450 (CYP) 2C11(9) and 1A2 - mediated drug metabolism.

RESULTS

In normal rats, the repeated dose administration of GAD induced a significant increase of BBR AUC and prolonged the mean residence time (MRT) (p < 0.05). systemic exposure to BBR and metabolically derived hydroxybenzbromarones was significantly greater in female compared with male rats (p < 0.05). In HN rats, post-administration of GAD resulted in significantly higher bioavailability and enterohepatic recycling (ER) of BBR relative to the BBR alone administrated group from the prolongation of terminal elimination half-life (T_1/2) and MRT of BBR (p < 0.05). Significantly higher urate-lowering effect of BBR+GAD compared with BBR alone was generally observed at post-dosing most time points with a maximal effect of 84.3% (acute treatment), 71.4% (7-day subchronic treatment) and 82.5% (14-day subchronic treatment) reduction in UA levels. Additionally, GAD showed a significant inhibitory effect on CYP2C11(9)-mediated tolbutamide (probe substrate) metabolism with ≥ 1.25 but < 2-fold increase in AUC_tolbutamide.

CONCLUSIONS

PD synergism demonstrated with the BBR+GAD combination could be explained by the PK interaction observed partially from CYP2C11(9)-mediation and enterohepatic recycling.

Tea Consumption is Associated with an Increased Risk of Hyperuricemia in an Occupational Population in Guangdong, China

Purpose

Chronic hyperuricemia leads to long-term deposition of monosodium urate crystals that may damage the joint structure and affect quality of life. Although hyperuricemia prevalence varies, most studies indicate increased cases of hyperuricemia worldwide. The relationship between hyperuricemia and tea consumption is uncertain. This cross-sectional study investigated the effect of tea consumption on the risk of hyperuricemia in the working population in Guangdong, China.

Patients and Methods

Data on weight, height, blood pressure, laboratory test results, and health questionnaire responses of 7644 adults aged ≥18 years were obtained from the health examinee dataset of Nanfang Hospital. The characteristics of subjects with and without hyperuricemia were compared using t-tests or non-parametric Mann–Whitney U-tests for continuous variables and chi-square tests for categorical variables. Relationships between hyperuricemia and participant characteristics (sex, age, education level, smoking history, alcohol consumption, hypertension, body mass index, tea consumption, and other dietary factors) were examined using univariate and multivariate logistic regression models to identify independent risk factors for hyperuricemia.

Results

Tea consumption was associated with a higher risk of hyperuricemia in the crude model (odds ratio [OR] 1.74, 95% confidence interval [CI] 1.48–2.05, once a month through twice a week vs never, P<0.001; OR 2.44, 95% CI 2.07–2.89, ≥3 times a week vs never, P<0.001). The adjusted OR for hyperuricemia was 1.30 (95% CI 1.08–1.56, P=0.006) in participants who consumed tea once a month through twice a week and 1.35 (95% CI 1.11–1.64, P=0.003) in those who consumed tea ≥3 times a week compared with the “never” reference group after adjusting for sociodemographic factors, anthropometric and biochemical indices, and dietary factors. This relationship remained significant in men but not women in subgroup analysis.

Conclusion

Tea consumption is an independent risk factor for hyperuricemia and is more pronounced in men than women.

Cordyceps cicadae Ameliorates Renal Hypertensive Injury and Fibrosis Through the Regulation of SIRT1-Mediated Autophagy

Hypertensive renal injury is a complication of hypertension. Cordyceps cicadae (C. cicadae) is a traditional Chinese medicine used to treat chronic kidney diseases especially renal fibrosis. Autophagy is described as a cell self-renewal process that requires lysosomal degradation and is utilized for the maintenance of cellular energy homeostasis. The present study explores the mechanism underlying C. cicadae’s renoprotection on hypertensive nephropathy (HN). First, HN rat models were established on spontaneously hypertensive rats (SHRs). The expression of fibrosis-related protein and autophagy-associated protein was detected in vivo. NRK-52E cells exposed to AngII were chosen to observe the potential health benefits of C. cicadae on renal damage. The level of extracellular matrix accumulation was detected using capillary electrophoresis immunoquantification and immunohistochemistry. After treatment with lysosomal inhibitors (chloroquine) or an autophagy activator (rapamycin), the expression of Beclin-1, LC3II, and SQSTM1/p62 was further investigated. The study also investigated the change in sirtuin1 (SIRT1), fork head box O3a (FOXO3a), and peroxidation (superoxide dismutase (SOD) and malondialdehyde (MDA)) expression when intervened by resveratrol. The changes in SIRT1 and FOXO3a were measured in patients and the SHRs. Here, we observed that C. cicadae significantly decreased damage to renal tubular epithelial cells and TGFβ1, α-smooth muscle actin (α-SMA), collagen I (Col-1), and fibronectin expression. Meanwhile, autophagy defects were observed both in vivo and in vitro. C. cicadae intervention significantly downregulated Beclin-1 and LC3II and decreased SQSTM1/p62, showing an inhibition of autophagic vesicles and the alleviation of autophagy stress. These functions were suppressed by rapamycin, and the results were just as effective as the resveratrol treatment. HN patients and the SHRs exhibited decreased levels of SIRT1 and FOXO3a. We also observed a positive correlation between SIRT1/FOXO3a and antifibrotic effects. Similar to the resveratrol group, the expression of SIRT1/FOXO3a and oxidative stress were elevated by C. cicadae in vivo. Taken together, our findings show that C. cicadae ameliorates tubulointerstitial fibrosis and delays HN progression. Renoprotection was likely attributable to the regulation of autophagic stress mediated by the SIRT1 pathway and achieved by regulating FOXO3a and oxidative stress.

Natural Flavonoid Pectolinarigenin Alleviated Hyperuricemic Nephropathy via Suppressing TGFβ/SMAD3 and JAK2/STAT3 Signaling Pathways

Natural flavonoid pectolinarigenin (PEC) was reported to alleviate tubulointerstitial fibrosis of unilateral ureteral obstruction (UUO) mice in our previous study. To further investigate nephroprotective effects of PEC in hyperuricemic nephropathy (HN), adenine and potassium oxonate induced HN mice and uric acid-treated mouse kidney epithelial (TCMK-1) cells were employed in the study. As a result, PEC significantly lowered serum uric acid level and restored hyperuricemia-related kidney injury in HN mice. Meanwhile, PEC alleviated inflammation, fibrosis, and reduced adipokine FABP4 content in the kidneys of HN mice and uric acid-treated TCMK-1 cells. Mechanistically, PEC inhibited the TGF-β1 expression as well as the phosphorylation of transcription factor SMAD3 and STAT3 to regulate the corresponding inflammatory and fibrotic gene expression in kidney tissues. In conclusion, our results suggested that PEC could inhibit the activation of SMAD3 and STAT3 signaling to suppress inflammation and fibrosis, and thereby alleviate HN in mice.

Depleted HDAC3 attenuates hyperuricemia-induced renal interstitial fibrosis via miR-19b-3p/SF3B3 axis

Dysfunctional histone deacetylases (HDACs) elicit unrestrained fibrosis and damage to organs. With regard to the link between HDACs and fibrosis, this research is practiced to decipher the concrete mechanism of HDAC3 in hyperuricemia (HN)-induced renal interstitial fibrosis (RIF) from microRNA-19b-3p/splicing factor 3b subunit 3 (miR-19b-3p/SF3B3) axis.The HN model was established on rats to induce RIF by oral administration of adenine and potassium oxalate. HN rats were injected with miR-19b-3p- or HDAC3-related vectors to figure out their effects on RIF through detecting 24-h urine protein, uric acid (UA), blood urea nitrogen (BUN) and serum creatinine (Scr) contents and α-smooth muscle actin (α-SMA), transforming growth factor β1 (TGF-β1) and fibronectin (FN) contents in renal tissues and observing pathological damages and RIF index of renal tissues. HDAC3, miR-19b-3p and SF3B3 expression in renal tissues were tested, along with their interactions.Elevated HDAC3 and SF3B3 and reduced miR-19b-3p were displayed in renal tissues of HN rats. Suppressed HDAC3 or promoted miR-19b-3p relieved HN-induced RIF, as reflected by their inhibitory effects on 24 h urine protein, UA, BUN, Scr, α-SMA, TGF-β1, and FN contents and RIF index and their ameliorated effects on pathological damages of renal tissues. HDAC3 bound to the promoter of miR-19b-3p to regulate SF3B3. MiR-19b-3p depletion abrogated down-regulated HDAC3-induced effects on HN-induced RIF.It is delineated that depressed HDAC3 relives HN-induced RIF through restoring miR-19b-3p and knocking down SF3B3, replenishing the references for RIF curing.

Synergy of epidermal growth factor (EGFR) and angiotensin II (AT1R) receptor determines composition and temporal pattern of transcriptome variation

The tyrosine kinase receptor EGFR and the G-protein-coupled receptor AT1R induce essential cellular responses, in part via receptor crosstalk with an unknown role in nuclear information transfer and transcription regulation. We investigated whether this crosstalk results in linear, EGFR-mediated nuclear signalling or in parallel, synergistic information transfer leading to qualitative and temporal variations, relevant for gene expression and environment interaction. AT1R and EGFR synergistically activate SRF via the ERK1/2-TCF and actin-MRTF pathways. Synergism, comprised of switch-like and graded single cell response, converges on the transcription factors AP1 and EGR, resulting in synergistic transcriptome alterations, in qualitative (over-additive number of genes), quantitative (over-additive expression changes of individual genes) and temporal (more late onset and prolonged expressed genes) terms. Gene ontology and IPA^® pathway analysis indicate prolonged cell stress (e.g. hypoxia-like) and dysregulated vascular biology. Synergism occurs during separate but simultaneous activation of both receptors and during AT1R-induced EGFR transactivation. EGFR and AT1R synergistically regulate gene expression in qualitative, quantitative and temporal terms with (patho)physiological relevance, extending the importance of EGFR-AT1R crosstalk beyond cytoplasmic signalling.

Drug Transporters in the Kidney: Perspectives on Species Differences, Disease Status, and Molecular Docking

The kidneys are a pair of important organs that excretes endogenous waste and exogenous biological agents from the body. Numerous transporters are involved in the excretion process. The levels of these transporters could affect the pharmacokinetics of many drugs, such as organic anion drugs, organic cationic drugs, and peptide drugs. Eleven drug transporters in the kidney (OAT1, OAT3, OATP4C1, OCT2, MDR1, BCRP, MATE1, MATE2-K, OAT4, MRP2, and MRP4) have become necessary research items in the development of innovative drugs. However, the levels of these transporters vary between different species, sex-genders, ages, and disease statuses, which may lead to different pharmacokinetics of drugs. Here, we review the differences of the important transports in the mentioned conditions, in order to help clinicians to improve clinical prescriptions for patients. To predict drug-drug interactions (DDIs) caused by renal drug transporters, the molecular docking method is used for rapid screening of substrates or inhibitors of the drug transporters. Here, we review a large number of natural products that represent potential substrates and/or inhibitors of transporters by the molecular docking method.

iTRAQ-based quantitative proteomic analysis reveals the toxic mechanism of diclofenac sodium on the kidney of broiler chicken

Diclofenac sodium (DS) is one of the nonsteroidal anti-inflammatory drugs (NSAIDs), which exhibits potent toxicity to birds. To search the molecular mechanism of DS induced nephrotoxicity in broiler chicken, 20 apparently healthy 30-day old broiler chickens were separated randomly into two groups (n = 10): Group A was kept as control while DS was administered at the dose rate of 10 mg/kg body weight in group B through oral gavage. Kidney samples were collected, and the proteins were identified and quantified by iTRAQ. 434 differentially expressed proteins (DEPs) were screened, including 277 up-regulated DEPs and 157 down-regulated DEPs. The functional annotation and classification results indicated that DEPs were significantly enriched in apoptosis and metabolism-related pathways via GO and KEGG analysis. Compared with the control group, the most significant enrichment pathways are "ribosome", "metabolic pathways" and "protein processing in endoplasmic reticulum". Based on the proteomic results and relevant literature, some DEPs that potentially related to the toxicity of DS were screened. The mRNA transcript levels of these DEPs were characterized by qRT-PCR, and the results showed that Slc22a7, Gatm, Glud1, Agxt2 and Gldc were significantly down-regulated, while Gsl, Gpt2 and Asns were significantly up-regulated. We speculate that the toxic mechanism of DS to chicken might be that it induces kidney cell apoptosis, interferes with purine metabolism and inhibits the expression of OAT2. The current study provides a reference for elucidating the nephrotoxic mechanism of diclofenac sodium to broiler chicken from the molecular perspective.

Constructing a passive targeting and long retention therapeutic nanoplatform based on water-soluble, non-toxic and highly-stable core-shell poly(amino acid) nanocomplexes

Drug delivery nanoplatforms have been applied in bioimaging, medical diagnosis, drug delivery and medical therapy. However, insolubility, toxicity, instability, nonspecific targeting and short retention of many hydrophobic drugs limit their extensive applications. Herein, we have constructed a passive targeting and long retention therapeutic nanoplatform of core-shell gefitinib/poly (ethylene glycol)-polytyrosine nanocomplexes (Gef-PY NCs). The Gef-PY NCs have good water-solubility, non-toxicity (correspond to 1/10 dosage of effective gefitinib (hydrochloride) (Gef·HCl) (normal drug administration and slow-release) and high stability (120 days, 80% drug retention at 4 or 25 °C). The core-shell Gef-PY NCs present unexpected kidney targeting and drug slow-release capacity (ca. 72 h). The good water-solubility, non-toxicity and high stability of Gef-PY NCs effectively solve the bottleneck question that Gef-based therapy could be used only in intraperitoneal injection due to its insolubility and severe toxicity. Such excellent properties (e.g., water-solubility, non-toxicity, high stability, kidney targeting and long retention) of Gef-PY NCs create their prominent anti-fibrosis capabilities, such as decreasing approximately 40% tubulointerstitial fibrosis area and 68% expression of collagen I within 7 days. This therapeutic efficacy is well-matched with that of 10 times the dosage of toxic Gef·HCl. It is very hopeful that Gef-PY NCs could realize clinical applications and such a strategy offers an effective route to design high-efficiency treatments for kidney- and tumor-related diseases.

Enhanced Efficacy and Reduced Hepatotoxicity by Combination of Gnaphalium affine Extract and Benzbromarone in the Treatment of Rats with Hyperuricemic Nephropathy

Simultaneous oral intake of herbal medicine with chemical drugs may result in beneficial pharmacodynamic efficacy, including additive and synergistic effects with reduced toxicity. Gnaphalium affine D. Don (GAD) is a traditional Chinese Medicine that has been used for the management of hyperuricemia and gout. Benzbromarone (BBR) is one of the first-line drugs used for urate-lowering therapy in China but is toxic to the liver. The present study aimed to determine the effects of GAD and BBR, both alone and in co-treatment (with dosing interval of 1 hour), on chronic hyperuricemic nephropathy (HN) and hepatotoxicity in rats. Our data indicated that GAD significantly inhibited the elevation of serum uric acid, blood urea nitrogen, and creatinine levels in chronic HN rats at doses of 450 and 900 mg/kg/day. The rise in serum alanine aminotransferase and aspartate aminotransferase in BBR (or vehicle)-treated HN rats was significantly reduced by pre- (or post)-administration of GAD (450 mg/kg/day). The q-value >1.15 (by Jin method) indicated synergistic effects of co-treatments of BBR (50 mg/kg) with GAD (450 mg/kg). The synergistic beneficial effects were validated by comparison of BBR alone at a dose of clinical usage (4.5 mg/kg/day, in two divided doses) and BBR + GAD at half dose plus half dose (2.25 + 225 mg/kg/day) or half dose plus full dose (2.25 + 450 mg/kg/day). In conclusion, co-treatment with GAD and BBR holds promise for the management of hyperuricemia and gout.

Sonneratia apetala seed oil attenuates potassium oxonate/hypoxanthine-induced hyperuricemia and renal injury in mice

Sonneratia apetala seeds are considered as prospective nutraceuticals with a high content of unsaturated fatty acids (UFAs) which are mainly distributed in the oil. It is well-known that UFAs could exhibit urate-lowering potency and protect against renal injury, indicating that S. apetala seed oil (SSO) may possess hypouricemic and nephroprotective effects. Consequently, the present work attempted to probe into the effects and mechanisms of SSO on potassium oxonate/hypoxanthine-induced hyperuricemia and associated renal injury. The results indicated that SSO treatment prominently inhibited the increase of serum uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) levels and hepatic xanthine oxidase (XOD) activity in hyperuricemia mice. Kidney indexes and histopathological lesions were also remarkably ameliorated. Additionally, SSO treatment improved the renal anti-oxidant status in hyperuricemia mice by significantly reversing the increase in ROS and MDA levels as well as the decline in SOD, CAT and GSH-Px activities. SSO dramatically downregulated the expression and secretion of pro-inflammatory factors involving MCP-1, IL-1β, IL-6, IL-18 and TNF-α elicited by hyperuricemia. Furthermore, after SSO treatment, increased protein expressions of GLUT9, URAT1 and OAT1 in the hyperuricemia mice were obviously reversed. SSO treatment enormously restored Nrf2 activation and subsequent translation of related anti-oxidative enzymes in the kidneys. TXNIP/NLRP3 inflammasome activation was also obviously suppressed by SSO. In conclusion, SSO exerted favorable hypouricemic effects owing to its dual functions of downregulating the XOD activity and modulating the expressions of renal urate transport-associated proteins, and it also could alleviate hyperuricemia-induced renal injury by restoring the Keap1-Nrf2 pathway and blocking the TXNIP/NLRP3 inflammasome activation.

Fisetin Improves Hyperuricemia-Induced Chronic Kidney Disease via Regulating Gut Microbiota-Mediated Tryptophan Metabolism and Aryl Hydrocarbon Receptor Activation

The intestinal flora serves a critical role in the development of hyperuricemia-induced chronic kidney disease (CKD). We previously found that natural flavonol fisetin exhibited nephroprotective effects in hyperuricemic mice. However, the mechanism remains largely unknown. To investigate the underlying mechanism of fisetin, mice were fed with potassium oxonate and adenine to introduce hyperuricemia-induced CKD. Fisetin improved kidney function, ameliorated renal fibrosis, and restored enteric dysbacteriosis in hyperuricemia-induced CKD mice. Meanwhile, gut microbiota-derived tryptophan metabolites, especially l-kynurenine, showed correlations with nephroprotective profiles of fisetin. Additionally, the kidney expression of the aryl hydrocarbon receptor (AHR), an endogenous receptor of l-kynurenine, was enhanced in hyperuricemic mice and further reduced in fisetin-treated mice. Finally, in vitro results showed that inhibition of AHR activation attenuated l-kynurenine-induced fibrosis. These results highlighted that fisetin protected against hyperuricemia-induced CKD via modulating gut microbiota-mediated tryptophan metabolism and AHR activation.

Mesenchymal stem cells transplantation attenuates hyperuricemic nephropathy in rats

Mesenchymal stem cells (MSCs), due to their multi-directional differentiation, paracrine and immunomodulation potentials, and the capacity of homing to target organ, have been reported to facilitate regeneration and repair of kidney and improve kidney function in acute or chronic kidney injury. The present study was aimed to evaluate whether MSCs could have a protective effect in hyperuricemic nephropathy (HN) and the underlying mechanisms. A rat HN model was established by oral administration of a mixture of potassium oxonate (PO, 1.5 g/kg) and adenine (Ad, 50 mg/kg) daily for 4 weeks. For MSCs treatment, MSCs (3 × 10⁶ cells/kg per week) were injected via tail vein from the 2nd week for 3 times. The results showed that along with the elevated uric acid (UA) in HN rats, creatinine (CREA), blood urea nitrogen (BUN), microalbuminuria (MAU) and 24-hour urinary protein levels were significantly increased comparing with the normal control rats, while decreased after MSCs treatment. Moreover, the mRNA levels of inflammation and fibrosis-related gene were reduced in UA + MSCs group. Consistently, hematoxylin-eosin (HE) staining results showed the destruction of kidney structure and fibrosis were significantly alleviated after MSCs administration. Similarly, in vitro, NRK-52Es cells were treated with high concentration UA (10 mg/dL) in the presence of MSCs, and we found that MSCs co-culture could inhibited UA-induced cell injury, characterized as improvement of cell viability and proliferation, inhibition of apoptosis, inflammation, and fibrosis. Collectively, MSCs treatment could effectively attenuate UA-induced renal injury, and thus it might be a potential therapy to hyperuricemia-related renal diseases.

Function of Uric Acid Transporters and Their Inhibitors in Hyperuricaemia

Disorders of uric acid metabolism may be associated with pathological processes in many diseases, including diabetes mellitus, cardiovascular disease, and kidney disease. These diseases can further promote uric acid accumulation in the body, leading to a vicious cycle. Preliminary studies have proven many mechanisms such as oxidative stress, lipid metabolism disorders, and rennin angiotensin axis involving in the progression of hyperuricaemia-related diseases. However, there is still lack of effective clinical treatment for hyperuricaemia. According to previous research results, NPT1, NPT4, OAT1, OAT2, OAT3, OAT4, URAT1, GLUT9, ABCG2, PDZK1, these urate transports are closely related to serum uric acid level. Targeting at urate transporters and urate-lowering drugs can enhance our understanding of hyperuricaemia and hyperuricaemia-related diseases. This review may put forward essential references or cross references to be contributed to further elucidate traditional and novel urate-lowering drugs benefits as well as provides theoretical support for the scientific research on hyperuricemia and related diseases.

Local NF-κB Activation Promotes Parathyroid Hormone Synthesis and Secretion in Uremic Patients

Secondary hyperparathyroidism (SHPT) in uremic patients is characterized by parathyroid gland (PTG) hyperplasia and parathyroid hormone (PTH) elevation. Previously, we demonstrated that NF-κB activation contributed to parathyroid cell proliferation in rats with chronic kidney disease. Although vitamin D inhibits inflammation and ameliorates SHPT, the contribution of vitamin D deficiency to SHPT via local NF-κB activation remains to be clarified. PTGs collected from 10 uremic patients with advanced SHPT were used to test the expressions of vitamin D receptor (VDR), NF-κB, and proliferating cell nuclear antigen (PCNA). Freshly excised PTG tissues were incubated for 24 hours in vitro with VDR activator (VDRA) calcitriol or NF-κB inhibitor pyrrolidine thiocarbamate (PDTC). Chromatin immunoprecipitation (ChIP) and luciferase reporter assays were performed to investigate the regulation of PTH transcription by NF-κB. We found higher levels of activated NF-κB and lower expression of VDR in nodular hyperplastic PTGs than in diffuse hyperplasia. In cultured PTG tissues, treatment with VDRA or PDTC inhibited NF-κB activation and PCNA expression, and downregulated preproPTH mRNA and intact PTH levels. ChIP assays demonstrated the presence of NF-κB binding sites in PTH promoter. Furthermore, in luciferase reporter assays, addition of exogenous p65 significantly increased PTH luciferase activity by 2.4-fold (P < 0.01), while mutation of NF-κB binding site at position -908 of the PTH promoter suppressed p65-induced PTH reporter activity (P < 0.01). In summary, local NF-κB activation contributes to SHPT and mediates the transcriptional activation of PTH directly in uremic patients. Vitamin D deficiency may be involved in SHPT via the activation of NF-κB pathway.

The Rho kinase signaling pathway participates in tubular mitochondrial oxidative injury and apoptosis in uric acid nephropathy

Introduction

Oxidative stress is a pathologic feature of hyperuricemia that is highly prevalent and that contributes to kidney tubular interstitial fibrosis. Rho-kinase is closely related to mitochondrial-induced oxidative stress. Herein, we designed a study to explore the expression and role of Rho-kinase in hyperuricemia nephropathy. The secondary objective was to investigate whether the Rho-kinase signaling pathway regulates hyperuricemic tubular oxidative injury and apoptosis via the mitochondrial pathway in addition to the mechanisms that are involved.

Materials and methods

HK-2 cells were divided into the following five groups: normal; uric acid (UA); UA+Fasudil; UA+ROCK1 si-RNA; and UA+sc-siRNA. Rho-kinase activity, mitochondrial oxidative injury, and apoptosis-related protein levels were measured in each group. A t-test was used to analyze the difference between groups.

Results

Myosin phosphatase target subunit 1 (MYPT1) overexpression was shown in HK-2 cells, which was caused by UA. High concentrations of UA also up-regulated Rho-kinase expression and mitochondrial and apoptosis-related protein expression, while treatment with fasudil and ROCK1 si-RNA significantly attenuated these responses.

Conclusion

The Rho-kinase signaling pathway participates in tubular mitochondrial oxidative injury and apoptosis via regulating mitochondrial dyneins/biogenic genes in UA nephropathy, which suggests that the mitochondrial pathway might be a potential therapeutic target for hyperuricemia nephropathy.

Vitamin C alleviates hyperuricemia nephropathy by reducing inflammation and fibrosis

Hyperuricemia contributes to chronic kidney disease development. However, it has been historically viewed with limited research interest. In this study, we mimicked the development of hyperuricemic nephropathy by using a potassium oxonate-induced hyperuricemia rat model. We found that administering vitamin C at 10 mg/kg/day effectively ameliorated hyperuricemic nephropathy. Compared to the control group, rats with hyperuricemia had significantly increased serum uric acid level, xanthine oxidase activity, and urine microalbumin level, by 5-fold, 1.5-fold, and 4-fold, respectively. At the same time, vitamin C supplementation reverted these values by 20% for serum uric acid level and xanthine oxidase activity and 50% for microalbumin level. Vitamin C also alleviated renal pathology and decreased the expression of pro-inflammatory and pro-fibrotic markers. A further mechanistic study suggested that vitamin C might attenuate hyperuricemic nephropathy in renal tubular epithelial cells induced by monosodium urate (MSU) crystal, at least in part, by directly inhibiting IL-6/JAK2/STAT3 signaling pathway. Meanwhile, in macrophages, vitamin C inhibited the expression of TGF-β, and reduced ROS level induced by MSU by about 35%. In short, our results suggest that vitamin C supplementation delay the progression of hyperuricemic nephropathy.

Tea consumption and serum uric acid levels among older adults in three large-scale population-based studies in China

Background and aims

The association between serum uric acid (SUA) and tea consumption has been studied in previous work, and there were arguments among various population group employed as well as different statistical approaches. The aim of this work is to investigate the tea effect on SUA levels among older adults by comparing three large-scale populations with both cross-sectional and longitudinal analyses.

Method

We examined the relationship between intake and SUA levels among older adults using linear regression. All the studies include the parameters SUA levels, tea intake, age, sex, education level, smoking status, alcohol drinking status, body mass index (BMI), and health history (diabetes, hypertension, and fasting plasma glucose). The cross-sectional analyses were conducted with 4579 older adults in the Weitang Geriatric Diseases Study (WGDS, ≥60 years), 2440 in the China Health and Nutrition Survey (CHNS, ≥60 years) and 1236 in the Chinese Longitudinal Healthy Longevity Survey (CLHLS, ≥62 years); and the longitudinal analyses were performed with 3870 (84.5%) in the WGDS and 420 (34.0%) in the CLHLS. Multivariable linear regression analyses were performed in both cross-sectional and longitudinal studies.

Results

Cross-sectional studies showed that tea consumers tended to have higher SUA levels than non-tea consumers in all the three datasets (P < 0.05). However, longitudinal associations of SUA levels with tea consumption had no statistical significance (P>0.05). The results of sex-stratified analyses were consistent with those of the whole datasets.

Conclusions

This work implied that any possible association between tea consumption and SUA levels could be very weak.

Hyperuricemia causes kidney damage by promoting autophagy and NLRP3-mediated inflammation in rats with urate oxidase deficiency

Epidemiological research has shown that elevated serum urate concentration is a risk factor for the development of kidney disease; however, the mechanisms underlying this process have not yet been elucidated. To examine the role of urate in the kidney, we used Wistar rats to functionally disrupt expression of urate oxidase (UOX) by using the CRISPR/Cas9 system. In comparison to wild-type (WT) rats, serum urate levels spontaneously and persistently increased in UOX-KO rats, without showing a significant decrease in survival rate. Architecture and function of the kidneys in UOX-KO rats were impaired. Injury to the kidney resulted in increased interstitial fibrosis, macrophage infiltration, increased expression of NLRP3 and IL-1β, and activation of multiple cell-signaling pathways associated with autophagy, such as AMPK, p38 MAPK, ERK and JNK pathways. Inhibition of autophagy with the PI3K inhibitor 3-MA abrogated the development of kidney damage and attenuated renal fibrosis, macrophage infiltration, and expression of NLRP3 and IL-1β in injured kidneys. In conclusion, the UOX-KO rat is a great model to study hyperuricemia-related diseases. Hyperuricemia-induced autophagy and NLRP3-dependent inflammation are critically involved in the development of renal damage and, therefore, highlight the inhibition of autophagy and inflammation in search of therapeutic strategies to treat uric acid nephropathy.

Natural flavonol fisetin attenuated hyperuricemic nephropathy via inhibiting IL-6/JAK2/STAT3 and TGF-β/SMAD3 signaling

BACKGROUND

The naturally occurring flavonol fisetin (3,3',4',7-tetrahydroxyflavone), widely dispersed in fruits, vegetables and nuts, has been reported to exert anti-inflammatory, antioxidant and anti-angiogenic effects. Our previous study indicated fisetin ameliorated inflammation and apoptosis in septic kidneys. However, the potential nephroprotective effect of fisetin in hyperuricemic mice remains unknown.

PURPOSE

The current study was designed to investigate the effect of fisetin on hyperuricemic nephropathy (HN) and explore the underlying mechanisms.

METHODS

The HN was induced in mice by mixing of potassium oxonate (2400 mg/kg) and adenine (160 mg/kg) in male C57BL/6J mice. Fisetin (50 or 100 mg/kg) was orally administrated either simultaneously with the establishment of HN or after HN was induced. As a positive control, allopurinol of 10 mg/kg was included. Uric acid levels in the serum and urine as well as renal function parameters were measured. Renal histological changes were measured by periodic acid-Schiff (PAS) and Masson's trichrome stainings. The expression of gene/protein in relation to inflammation, fibrosis, and uric acid excretion in the kidneys of HN mice or uric acid-treated mouse tubular epithelial (TCMK-1) cells were measured by RNA-seq, RT-PCR, western blot and immunohistochemical analysis.

RESULTS

Treatment with fisetin, regardless of administration regimen, dose-dependently attenuated hyperuricemia-induced kidney injury as indicated by the improved renal function, preserved tissue architecture, and decreased urinary albumin-to-creatinine ratio. Additionally, fisetin lowered uricemia by modulating the expression of kidney urate transporters including urate transporter 1(URAT1), organic anion transporter 1 (OAT1), organic anion transporter 3 (OAT3) and ATP binding cassette subfamily G member 2 (ABCG2). Moreover, hyperuricemia-induced secretions of proinflammatory factors including tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6) and monocyte chemoattractant protein-1(MCP-1) in HN mice and uric acid-stimulated TCMK-1 cells were mitigated by fisetin treatment. Meanwhile, fisetin attenuated kidney fibrosis in HN mice with restored expressions of alpha-smooth muscle actin (α-SMA), collagen I and fibronectin. Mechanistically, fisetin regulated the aberrant activation of signal transducer and activator of transcription-3 (STAT3) signaling and transforming growth factor-β (TGF-β) signaling in the HN kidneys and uric acid-stimulated TCMK-1 cells.

CONCLUSION

Fisetin lowered uricemia, suppressed renal inflammatory response, and improved kidney fibrosis to protect against hyperuricemic nephropathy via modulation of STAT3 and TGF-β signaling pathways. The results highlighted that fisetin might represent a potential therapeutic strategy against hyperuricemic nephropathy.

Histone Methyltransferase EZH2: A Potential Therapeutic Target for Kidney Diseases

Enhancer of zeste homolog 2 (EZH2) is a histone-lysine N-methyltransferase enzyme that catalyzes the addition of methyl groups to histone H3 at lysine 27, leading to gene silencing. Mutation or over-expression of EZH2 has been linked to many cancers including renal carcinoma. Recent studies have shown that EZH2 expression and activity are also increased in several animal models of kidney injury, such as acute kidney injury (AKI), renal fibrosis, diabetic nephropathy, lupus nephritis (LN), and renal transplantation rejection. The pharmacological and/or genetic inhibition of EZH2 can alleviate AKI, renal fibrosis, and LN, but potentiate podocyte injury in animal models, suggesting that the functional role of EZH2 varies with renal cell type and disease model. In this article, we summarize the role of EZH2 in the pathology of renal injury and relevant mechanisms and highlight EZH2 as a potential therapeutic target for kidney diseases.

Pharmacologic Targeting of BET Proteins Attenuates Hyperuricemic Nephropathy in Rats

Hyperuricemia is an independent risk factor for renal damage and promotes the progression of chronic kidney disease. In this study, we investigated the effect of I-BET151, a small-molecule inhibitor targeting the bromodomain and extraterminal (BET) proteins, on the development of hyperuricemic nephropathy (HN), and the mechanisms involved. Expression levels of bromodomain-containing protein 2 and 4, but not 3 were increased in the kidney of rats with HN; administration of I-BET151 effectively prevented renal dysfunction, decreased urine microalbumin, and attenuated renal fibrosis as indicated by reduced activation of renal interstitial fibroblasts and expression of fibronectin and collagen I in HN rats. Mechanistic studies show that I-BET151 treatment inhibited transition of renal epithelial cells to a mesenchymal cell type as evidenced by preservation of E-cadherin and reduction of vimentin expression. This was coincident with reduced expression of TGF-β1 and dephosphorylation of Smad3 and ERK1/2. I-BET151 was also effective in inhibiting phosphorylation of NF-κB, expression of multiple cytokines and chemokines, and infiltration of macrophages to the injured kidney. Although there were increased serum levels of uric acid and xanthine oxidase, an enzyme that catalyzes production of uric acid, and decreased expression of renal organic anion transporter 1 and 3 that promote urate excretion in the model of HN, and reduced expression levels of urine uric acid, I-BET151 treatment did not affect these responses. Collectively, our results indicate that I-BET151 alleviates HN by inhibiting epithelial to mesenchymal transition and inflammation in association with blockade of TGF-β, ERK1/2 and NF-κB signaling.