Uric acid (UA), the final product of human purine metabolism, can cause hyperuricemia (HUA) when excessively accumulated. HUA is closely linked to chronic kidney diseases (CKD) and is considered an independent risk factor. Hyperuricemic nephropathy, a form of CKD induced by HUA, has seen significant advances in understanding through research into the pathogenic roles of uric acid and the development of HUA animal models. Although progress has been made in understanding the pathophysiological mechanisms by which UA induces CKD, much remains to be learned about its pathological molecular mechanisms. New approaches in animal modeling or the selection of model animals may potentially lead to significant breakthroughs in research on hyperuricemia as well as related CKD. This paper reviews the research progress on the molecular mechanisms of hyperuricemic nephropathy, focusing on oxidative stress, inflammation, autophagy, fibrosis, and gut microbiota. Oxidative stress is induced by uric acid intracellularly through xanthine oxidase, NADPH oxidases, and mitochondria, leading to cellular damage. In terms of inflammation, uric acid crystals can activate the NLRP3 inflammasome, triggering an inflammatory cascade. The role of free uric acid as a pro-inflammatory agent, however, remains controversial. Depending on the study conducted, autophagy has been found to either alleviate or exacerbate inflammation induced by uric acid. Fibrosis, particularly through epithelial-mesenchymal transition (EMT), is a major mechanism by which uric acid causes glomerulosclerosis and tubulointerstitial fibrosis. Extensive research has explored various signaling pathways involved in uric acid-induced EMT. Beneficial gut microbiota protect the kidneys by synthesizing short-chain fatty acids, reducing urea’s enterohepatic circulation, and decreasing uric acid production. This paper aims to enhance understanding of the complex relationships between HUA and CKD, serving as a reference for further research and new drug development.

Objective To observe the effects of different ligation sites and fasting method on a C57BL/6J mouse model of partial bile duct ligation(pBDL)-induced cholestasis,to establish a pBDL modeling method with a high modeling rate,typical symptoms,and good stability.Methods C57BL/6J mice were subjected to selective ligation of the left hepatic bile duct(L-pBDL)and left-to-median bile duct junction ligation(ML-pBDL)for modeling,and the effects of different pBDL ligation method on serum alanine aminotransferase,aspartate aminotransferase,alkaline phosphatase(ALP),total bilirubin,total bile acid,and liver histopathology were observed.The effects of different fasting method on symptoms and liver injury in the ML-pBDL model were also observed after fasting for 12 and 16 h before surgery,and for 4 h after surgery.Results(1)The incidence of jaundice in the ML-pBDL group was 52.94%and the survival rate within 3 weeks after surgery was 64.71%,while the incidence of jaundice in the L-pBDL group was 11.76%and the survival rate within 3 weeks after surgery was 82.35%.Compared with those in the sham surgery group,serum liver function indicators were significantly increased in the L-pBDL and ML-pBDL groups(P＜0.01),and ALP activity was significantly higher in the ML-pBDL group than in the L-pBDL group(P＜0.05).Compared with mice in the L-pBDL group,mice in the ML-pBDL group had more severe liver fibrosis at 3 weeks post-surgery(P＜0.01).(2)In addition,the incidence of jaundice in the 16 h fasting group was 93.33%and the survival rate within 3 weeks after surgery was 73.77%,while the incidence of jaundice in the 12 h fasting group was 42.86%and the survival rate within 3 weeks after surgery was 71.42%.Compared with those in the normal group,ALP activity,alanine aminotransferase/aspartate aminotransferase ratio,total bile acid level,and proportion of collagen fiber area were all significantly increased in the 16 h and 12 h fasting groups(P＜0.05).Although the observed indicators were higher in the 16 h fasting group compared with those in the 12 h fasting group,the difference was not significant(P＞0.05).Mice in the 12 h and 16 h fasting groups both showed significant bile duct hyperplasia and liver fibrosis(P＜0.01),with more severe liver fibrosis in the 16 h fasting group(P＜0.01).Conclusions Both L-pBDL and ML-pBDL ligation method can be used to establish a mouse model of cholestasis;however,symptoms in the L-pBDL model only exhibit transient damage characteristics,while the liver lesions in the ML-pBDL model are typical and stable.Prolonging the preoperative fasting time can improve the modeling rate and stability of the ML-pBDL model and produce more-typical pathological symptoms.

Objective To establish a rat model of hyperuricemic nephropathy(HN)using a multifactorial induction method of potassium oxazinate combined with adenine and yeast feed to observe the intervention effect of Qiling granules(QLG).Methods Fifty-eight SPF-grade male SD rats were selected,and 10 rats were randomly allocated to the normal control(NC)group.The remaining rats were induced by multiple factors to establish HN rat models.After 2 weeks of modeling,submandibular blood samples were taken to detect serum UA,CREA,BUN,TG,and TC.Forty HN rats with bleeding clearance UA and body weight close to the mean were selected.They were randomly divided into a model(M)group,QLG low dose(QLG-L)groups,QLG high dose(QLG-H)group,and a positive control(PC)group,with 10 rats in each group,using a stratified randomization method.Each group was given corresponding drugs by gavage daily,and after continuous administration for 4 weeks,submandibular blood samples were taken to detect serum UA,CREA,BUN,TG,and TC.After euthanasia of the rats,liver tissue was taken to detect XOD and ADA activity.Renal tissue was taken for HE and Gomori hexamine silver staining,and the protein expression of GLUT9,OAT1,VCAM-1,and TGF-β in the kidneys was observed using immunohistochemistry and Western blot method.Results Compared with the NC group,the M group's serum levels of UA,CREA,BUN,TC,and TG,as well as liver XOD and ADA activities,were significantly increased(P＜0.01).The renal tissue of the model rats showed significant pathological changes.The area of renal tubules positive for urate and the expression of GLUT9,VCAM-1,and TGF-β proteins in the kidneys were significantly increased(P＜0.01,P＜0.05),while the expression of OAT1 was significantly reduced(P＜0.01).Compared with the M group,each treatment group showed significantly reduced serum UA levels,liver XOD,ADA activity,and renal VCAM-1 protein expression(P＜0.01,P＜0.05).The serum CREA and BUN levels and renal TGF-β protein expression of rats in the QLG-L group were significantly reduced(P＜0.05,P＜0.01).The serum CREA and BUN levels and renal GLUT9 protein expression of rats in the QLG-H group were also significantly reduced(P＜0.01,P＜0.05).The urate deposition and renal injury caused by each treatment were reduced to varying degrees,but there were no significant differences among groups(P＞0.05).Conclusions A stable HN rat model can be induced by gavage of potassium oxyzinate and adenine in combination with yeast feed.QLG can effectively treat HN by improving UA metabolic disorders,reducing the renal inflammation and urate deposition that cause renal damage in HN model rats.Its mechanism of action is related to a reduction in serum UA,CREA,BUN,and TG levels;liver XOD and ADA activities;and the expression of GLUT9,OAT1,VCAM-1,and TGF-β proteins in the kidneys.