Rat Model Of Chronic Kidney Disease Research Articles

Study on the mechanism of hirudin multi target delaying renal function decline in chronic kidney disease based on the "gut-kidney axis" theory.

The disorder of the "gut-kidney axis" exacerbates renal function decline in chronic kidney disease (CKD), and current CKD therapy is insufficient to address this issue. Hirudin has a palliative effect on the decline of renal function. However, whether hirudin can delay CKD by regulating the "intestinal renal axis" disorder remains unclear. Unilateral ureteral ligation (UUO) induced CKD rat model, and the rats were treated with bifidobacterium and hirudin for 36 days. After 14 and 36 days of modeling, kidney and colon tissues were collected for pathology, western blot (WB) assay, and quantitative real-time PCR (qPCR) detection. Serum samples were collected for renal function testing. Fecal samples were used for 16S rRNA sequencing and research on fecal bacterial transplantation. Lipopolysaccharide combine with adenosine 5'-triphosphate (LPS + ATP)-induced intestinal epithelial cell injury was treated with a nod-like receptor pyrin domain-associated protein 3 (NLRP3) inhibitor and hirudin. Protein expression was detected using WB and qPCR. The kidneys and colons of the CKD rats exhibited varying degrees of lesions. Creatinine (CRE), blood urea nitrogen (BUN), N-acetyl-β-D-glucosidase (NAG) enzyme, and serum uremic toxins were elevated. The expression of claudin-1 and occludin was decreased, NLRP3 inflammatory-related proteins were increased, and the gut microbiota was disrupted. These pathological changes were more pronounced after 36 days of modeling. Meanwhile, high-dose hirudin treatment significantly improved these lesions and restored the intestinal flora to homeostasis in CKD rats. In vitro, hirudin demonstrated comparable effects to NLRP3 inhibitors by upregulating claudin-1 and occludin expression, and downregulating NLRP3 inflammatory-related proteins expression. The dysbiosis of the gut microbiota and impaired intestinal epithelial barrier function in CKD are associated with renal dysfunction in CKD. Hirudin delays the progression of CKD by regulating the disorder of the "gut-kidney axis" and inhibiting the activation of the NLRP3-ASC-caspase-1 pathway.

Kidney disease associated with pre-pubertal obesity initiates pathological alterations in the brain of Dahl salt-sensitive rats

Childhood/pre-pubertal obesity (PPO) is implicated in the development of chronic kidney disease (CKD), and there is evidence that PPO also increases the risk of developing Alzheimer disease (AD) later in life. In the current study, we aim to investigate the correlation between CKD and the development of AD-like pathology in a rat model of CKD associated with PPO. We hypothesize that systemic inflammation due to PPO exacerbates CKD and induces AD-like pathology in the brain at older age. In our preliminary studies, we utilized the Dahl salt sensitive leptin receptor mutant rat (SSLepRmutant), which is a novel model of PPO. 6-week-old Dahl salt-sensitive (SS) (control, n=3) and SSLepRmutant rats (n=5) were monitored for proteinuria every 3 weeks, for a 12-week period. Throughout the study, we observed significantly elevated proteinuria in SSLepRmutant rats (Week-6: 337±81 mg/day, Week-9: 371±147 mg/day, Week-18: 1920±318 mg/day) compared to SS rats (Week-6: 25±7 mg/day, Week-9: 35±39 mg/day, Week-18: 35±33 mg/day). At 18-week, creatinine levels were significantly higher in SSLepRmutant rats (1.5±0.5 mg/dL) versus SS rats (0.4±0.03 mg/dL) indicating CKD. Additionally, we found significant elevation of triglycerides in SSLepRmutant rats (5134±1211 mg/dL) compared to SS rats (79±21 mg/dL). To investigate the brain pathology, we performed immunochemical analysis (dot-blot assay) using A11 antibody to determine the levels of Amyloid-beta oligomers (Aβo). Our results show that there was tendency for Aβo levels to be increased in the brains from obese SSLepRmutant rats compared to SS. Finally, we tested the permeability of the blood-brain barrier to Evans blue dye and observed that the brain of SSLepRmutant rats was more permeable to the dye compared to SS rats as early as 8 weeks of age. Overall, these results indicate that PPO obesity not only increases the susceptibility to develop CKD but also causes Alzheimer-like pathology during the prepubescent stage. NIDDK (DK109133) and AG (AG057842) awarded to Jan M. Williams. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of cholecalciferol and omega-3 fatty acids on hepcidin levels in 5/6 nephrectomy rats

Background: Anemia is a common complication of chronic kidney disease (CKD). In patients with CKD-related anemia, an inverse relationship between vitamin D and hepcidin levels has been observed. Hepcidin is a key regulator of iron homeostasis, mediated via binding to ferroportin. The aim of this study was to investigate the effects of cholecalciferol and omega-3 fatty acids (FA) on hepcidin levels using 5/6 nephrectomized (Nx) rats.Methods: Male Sprague-Dawley rats were divided into five groups: sham control, 5/6 Nx, 5/6 Nx treated with cholecalciferol, 5/6 Nx treated with omega-3 FA, and 5/6 Nx treated with both cholecalciferol and omega-3 FA. We measured the hepcidin and ferroportin levels in the kidney and liver by enzyme-linked immunosorbent assays and Western blots. We evaluated hepcidin expression in the kidney by immunohistochemical staining.Results: Among the five groups, 5/6 Nx rats exhibited the worst kidney function. Compared with the sham controls, 5/6 Nx rats showed significantly increased serum hepcidin levels and decreased vitamin D levels. Supplementation with either omega-3 FA or cholecalciferol decreased hepcidin and increased vitamin D levels, with a concurrent improvement of anemia. Furthermore, 5/6 Nx rats treated with omega-3 FA/cholecalciferol showed decreased ferroportin and ferritin levels, while iron and total iron-binding capacity levels increased.Conclusions: Treatment with a combination of cholecalciferol and omega-3 FA may improve anemia in a CKD rat model by decreasing hepcidin levels.

Linking renal hypoxia and oxidative stress in chronic kidney disease: Based on clinical subjects and animal models.

This study aims to explore the relationships between renal function, hypoxia, and oxidative stress in chronic kidney disease (CKD). Seventy-six non-dialysis patients with CKD stages 1-5 and eight healthy subjects were included in the clinical research. They were divided into three groups: healthy subjects, CKD stages 1-3, and CKD stages 4-5. In the animal study, 16 rat models of CKD were established through 5/6 renal ablation/infarction (A/I) surgery, and 8 normal rats were split into 3 groups: Sham, CKD, and losartan groups. Blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) was used to measure cortical and medullary T2* values (COT2* and MET2*) in all subjects and rats to evaluate renal oxygenation. Biochemical indicators were used to assess renal function and antioxidant capacity. Furthermore, the effects of losartan on renal fibrosis, hypoxia, and oxidative stress were examined using immunoblotting, colorimetric, and fluorometric assays. The results demonstrated significant positive associations between COT2* and MET2* with estimated glomerular filtration rate (eGFR). Patients with CKD stages 4-5 showed significantly lower serum superoxide dismutase (SOD) levels, which also had positive correlations with eGFR, COT2*, and MET2*. Furthermore, losartan treatment resulted in improved renal function and fibrosis, leading to increased levels of COT2*, MET2*, and SOD levels in 5/6 A/I rats. This was accompanied by reduced levels of hypoxia-inducible factor-1 alpha (HIF-1α) and malondialdehyde. Furthermore, losartan restored the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and suppressed the expression of Kelch-like ECH-associated protein 1 (Keap1) in 5/6 A/I kidneys. The study indicates that decline in renal oxygenation and antioxidant capacity is associated with the severity of renal failure in CKD. Losartan can potentially alleviate renal hypoxia and oxidative stress in the treatment of CKD via Keap1-Nrf2/HO-1 pathway.

Liver and spleen predominantly mediate calciprotein particle clearance in a rat model of chronic kidney disease.

Calciprotein particles (CPPs) provide an efficient mineral buffering system to prevent the complexation of phosphate and calcium in the circulation. However, in chronic kidney disease (CKD), the phosphate load exceeds the mineral buffering capacity, resulting in the formation of crystalline CPP2 particles. CPP2 have been associated with cardiovascular events and mortality. Moreover, CPP2 have been demonstrated to induce calcification in vitro. In this study, we examined the fate of CPP2 in a rat model of CKD. Calcification was induced in Sprague-Dawley rats by 5/6 nephrectomy (5/6-Nx) combined with a high-phosphate diet. Control rats received sham surgery and high-phosphate diet. Twelve weeks after surgery, kidney failure was significantly induced in 5/6-Nx rats as determined by enhanced creatinine and urea plasma levels and abnormal kidney histological architecture. Subsequently, radioactive and fluorescent (FITC)-labeled CPP2 ([89Zr]Zr-CPP2-FITC) were injected intravenously to determine clearance in vivo. Using positron emission tomography scans and radioactive biodistribution measurements, it was demonstrated that [89Zr]Zr-CPP2-FITC are mainly present in the liver and spleen in both 5/6-Nx and sham rats. Immunohistochemistry showed that [89Zr]Zr-CPP2-FITC are predominantly taken up by Kupffer cells and macrophages. However, [89Zr]Zr-CPP2-FITC could also be detected in hepatocytes. In the different parts of the aorta and in the blood, low values of [89Zr]Zr-CPP2-FITC were detectable, independent of the presence of calcification. CPP2 are cleared rapidly from the circulation by the liver and spleen in a rat model of CKD. In the liver, Kupffer cells, macrophages, and hepatocytes contribute to CPP2 clearance.NEW & NOTEWORTHY Calciprotein particles (CPPs) buffer calcium and phosphate in the blood to prevent formation of crystals. In CKD, increased phosphate levels may exceed the buffering capacity of CPPs, resulting in crystalline CPPs that induce calcification. This study demonstrates that labeled CPPs are predominantly cleared from the circulation in the liver by Kupffer cells, macrophages, and hepatocytes. Our results suggest that targeting liver CPP clearance may reduce the burden of crystalline CPP in the development of vascular calcification.

Musculoskeletal Health Worsened from Carnitine Supplementation and Not Impacted by a Novel Individualized Treadmill Training Protocol

Introduction: Chronic kidney disease (CKD) negatively affects musculoskeletal health, leading to reduced mobility, and quality of life. In healthy populations, carnitine supplementation and aerobic exercise have been reported to improve musculoskeletal health. However, there are inconclusive results regarding their effectiveness and safety in CKD. We hypothesized that carnitine supplementation and individualized treadmill exercise would improve musculoskeletal health in CKD. Methods: We used a spontaneously progressive CKD rat model (Cy/+ rat) (n = 11–12/gr): (1) Cy/+ (CKD-Ctrl), (2) CKD-carnitine (CKD-Carn), and (3) CKD-treadmill (CKD-TM). Carnitine (250 mg/kg) was injected daily for 10 weeks. Rats in the treadmill group ran 4 days/week on a 5° incline for 10 weeks progressing from 30 min/day for week one to 40 min/day for week two to 50 min/day for the remaining 8 weeks. At 32 weeks of age, we assessed overall cardiopulmonary fitness, muscle function, bone histology and architecture, and kidney function. Data were analyzed by one-way ANOVA with Tukey’s multiple comparisons tests. Results: Moderate to severe CKD was confirmed by biochemistries for blood urea nitrogen (mean 43 ± 5 mg/dL CKD-Ctrl), phosphorus (mean 8 ± 1 mg/dL CKD-Ctrl), parathyroid hormone (PTH; mean 625 ± 185 pg/mL CKD-Ctrl), and serum creatinine (mean 1.1 ± 0.2 mg/mL CKD-Ctrl). Carnitine worsened phosphorous (mean 11 ± 3 mg/dL CKD-Carn; p p p p p Conclusion: Carnitine supplementation worsened CKD progression, mineral metabolism biochemistries, and cortical porosity and did not have an impact on physical function. Individualized treadmill running improved maximal aerobic capacity but did not have an impact on CKD progression or bone properties. Future studies should seek to better understand carnitine doses in conditions of compromised renal function to prevent toxicity which may result from elevated carnitine levels and to optimize exercise prescriptions for musculoskeletal health.

The protective effect and mechanism of piperazine ferulate in rats with 5/6 nephrectomy-caused chronic kidney disease.

Chronic kidney disease (CKD) is a type of chronic disease in which multiple factors are responsible for the structural and functional disorders of the kidney. Piperazine ferulate (PF) has anti-platelet and anti-fibrotic effects, and its mechanism of action remains to be elucidated. This study aimed to investigate the protective effect of PF against CKD in rats and to determine its mechanism of action. Network pharmacology was used to predict potential PF action targets in the treatment of CKD and to further validate them. A rat model of CKD was established; blood was collected, etc., for the assessment of the renal function; renal pathologic damage was examined using hematoxylin and eosin (HE) staining and Masson staining; changes in the levels of TGF-β1 and α-SMA were determined with ELISA; EPOR, FN, and COL I expression were detected utilizing immunohistochemistry; and HIF-1α, HIF-2α, and EPO protein molecules were analyzed deploying western blotting. PF reduces Scr, BUN, and 24h UP levels; decreases FN and COL I expression; and attenuates renal injury. Additionally, PF inhibited TGF-β1 and stimulated the production of HIF-1α and HIF-2α, which downregulated α-SMA and upregulated EPO. PF attenuated the progression of the CKD pathology, and the mechanism of its action is possibly associated with the promotion of HIF-1α/HIF-2α/EPO production and TGF-β1 reduction.

Colonic microflora and plasma metabolite-based comparative analysis of unilateral ureteral obstruction-induced chronic kidney disease after treatment with the Chinese medicine FuZhengHuaYuJiangZhuTongLuo and AST-120

BackgroundMany researchers have investigated the use of Chinese herbs to delay the progression of chronic kidney disease (CKD) through their effects on colonic microflora and microbiota-derived metabolites. However, whether FuZhengHuaYuJiangZhuTongLuo (FZHY) has effects that are similar to those of AST-120 on CKD needs to be elucidated. MethodsIn this study, we compared the effects of FZHY and AST-120 on the colonic microbiota and plasma metabolites in the CKD rat model. We developed a unilateral ureteral obstruction (UUO)-induced CKD rat model and then administered FZHY and AST-120 to these model rats. Non-targeted metabolomic LC-MS analysis, 16S rRNA sequencing, and histopathological staining were performed on plasma, stool, and kidney tissues, respectively, and the joint correlation between biomarkers and metabolites of candidate bacteria was analyzed. ResultsOur results showed that administering FZHY and AST-120 effectively ameliorated UUO-induced abnormal renal function and renal fibrosis and regulated the composition of microbiota and metabolites. Compared to the UUO model group, the p_Firmicutes and o_Peptostreptococcales_Tissierellales were increased, while 14 negative ion metabolites were upregulated and 21 were downregulated after FZHY treatment. Additionally, 40 positive ion metabolites were upregulated and 63 were downregulated. On the other hand, AST-120 treatment resulted in an increase in the levels of g_Prevotellaceae_NK3B31_group and f_Prevotellaceae, as well as 12 upregulated and 23 downregulated negative ion metabolites and 56 upregulated and 63 downregulated positive ion metabolites. Besides, FZHY increased the levels of candidate bacterial biomarkers that were found to be negatively correlated with some poisonous metabolites, such as 4-hydroxyretinoic acid, and positively correlated with beneficial metabolites, such as l-arginine. AST-120 increased the levels of candidate bacterial biomarkers that were negatively correlated with some toxic metabolites, such as glycoursodeoxycholic acid, 4-ethylphenol, and indole-3-acetic acid. ConclusionFZHY and AST-120 effectively reduced kidney damage, in which, the recovery of some dysregulated bacteria and metabolites are probably involved. As their mechanisms of regulation were different, FZHY might play a complementary role to AST-120 in treating CKD.

Elevated luminal inorganic phosphate suppresses intestinal Zn absorption in 5/6 nephrectomized rats.

Zinc (Zn) is an essential trace element in various biological processes. Chronic kidney disease (CKD) often leads to hypozincemia, resulting in further progression of CKD. In CKD, intestinal Zn absorption, the main regulator of systemic Zn metabolism, is often impaired; however, the mechanism underlying Zn malabsorption remains unclear. Here, we evaluated intestinal Zn absorption capacity in a rat model of CKD induced by 5/6 nephrectomy (5/6 Nx). Rats were given Zn and the incremental area under the plasma Zn concentration-time curve (iAUC) was measured as well as the expression of ZIP4, an intestinal Zn transporter. We found that 5/6 Nx rats showed lower iAUC than sham-operated rats, but expression of ZIP4 protein was upregulated. We therefore focused on other Zn absorption regulators to explore the mechanism by which Zn absorption was substantially decreased. Because some phosphate compounds inhibit Zn absorption by coprecipitation and hyperphosphatemia is a common symptom in advanced CKD, we measured inorganic phosphate (Pi) levels. Pi was elevated in not only serum but also the intestinal lumen of 5/6 Nx rats. Furthermore, intestinal intraluminal Pi administration decreased the iAUC in a dose-dependent manner in normal rats. In vitro, increased Pi concentration decreased Zn solubility under physiological conditions. Furthermore, dietary Pi restriction ameliorated hypozincemia in 5/6 Nx rats. We conclude that hyperphosphatemia or excess Pi intake is a factor in Zn malabsorption and hypozincemia in CKD. Appropriate management of hyperphosphatemia will be useful for prevention and treatment of hypozincemia in patients with CKD.NEW & NOTEWORTHY We demonstrated that elevated intestinal luminal Pi concentration can suppress intestinal Zn absorption activity without decreasing the expression of the associated Zn transporter. Increased intestinal luminal Pi led to the formation of an insoluble complex with Zn while dietary Pi restriction or administration of a Pi binder ameliorated hypozincemia in chronic kidney disease model rats. Therefore, modulation of dietary Pi by Pi restriction or a Pi binder might be useful for the treatment of hypozincemia and hyperphosphatemia.

D-box-binding protein alleviates vascular calcification in rats with chronic kidney disease by activating microRNA-195-5p and downregulating cyclin D1.

Vascular calcification (VC) is a critical complication in chronic kidney disease (CKD), where transcription factors (TFs) and microRNAs (miRs) could potentially play a pivotal role in its pathogenesis and progression. To explore the potential molecular mechanism by which the TF D-box-binding protein (DBP) regulates the miR-195-5p/cyclin D1 (CCND1) axis and its impact on aortic VC in CKD rats, we established a rat model of CKD with VC through a 5/6 nephrectomy procedure. This model was treated with lentivirus overexpressing DBP or CCND1 to analyze their roles in aortic VC. Additionally, an in vitro cell model of VC was induced by high phosphorus. This model underwent transfection with lentivirus overexpressing DBP or miR-195-5p mimic/inhibitor to confirm their regulatory roles in aortic VC in vitro. We assessed the interactions between DBP and miR-195-5p, as well as between miR-195-5p and CCND1. Our results indicated that the expression of DBP and miR-195-5p was reduced, while CCND1 levels were elevated in both the rat and cell models. Overexpression of miR-195-5p inhibited VC in vascular smooth muscle cells (VSMCs). Bioinformatics prediction and dual luciferase assays confirmed that DBP could act as a TF to enhance miR-195-5p expression, with Ccnd1 identified as a downstream target gene of miR-195-5p. Overexpression of DBP inhibited aortic calcification in CKD rats, whereas overexpression of CCND1 produced the opposite effect. In conclusion, the TF DBP can inhibit CCND1 expression through transcriptional activation of miR-195-5p, thereby preventing VC in rats with CKD.

Role of symbiotic microbiota dysbiosis in the progression of chronic kidney disease accompanied with vascular calcification.

Background: Chronic kidney disease (CKD) is now globally recognized as a critical public health concern. Vascular calcification (VC) represents a significant risk factor for cardiovascular events in individuals with CKD. It is the accessible and precise diagnostic biomarkers for monitoring the progression of CKD and the concurrent VC are urgently needed. Methods: The adenine diet-induced CKD rat model was utilized to investigate chronic kidney injury, calcification in the kidney and thoracic aorta, and dysregulation of biochemical indices. Enzyme-linked immune sandwich assays were employed to analyze changes in calcification-related proteins. 16S rRNA sequencing was performed to delineate the microbiota characteristics in the gut and blood of CKD-afflicted rats. Additionally, transcriptome sequencing of kidney tissue was conducted to explore the relationship between CKD-associated microbiota features and alterations in kidney function. Results: The adenine diet-induced CKD inhibited body weight gain, and led to kidney injury, and pronounced calcification in kidney and thoracic aorta. The microbiota both in the gut and blood of these affected rats exhibited significantly lower alpha diversity and distinctive beta diversity than those in their healthy counterparts. CKD resulted in dysregulation of several biochemical indices (including elevated levels of creatinine, low-density lipoprotein-cholesterol, sodium, phosphorous, total cholesterol, and urea and decreased levels of albumin, calcium, lactate dehydrogenase, and total bilirubin). Moreover, it upregulated calcification-related factors (bone sialoprotein [BSP], Klotho, fibroblast growth factor [FGF]-23, and sclerostin [SOST]) and lipopolysaccharide (LPS). Notably, the increased Acinetobacter in the blood was positively associated with calcifications in the kidney and thoracic aorta, in addition to the positive correlation with gut microbiota. The enrichment of Acinetobacter was concurrent with increases in calcification factors (BSP, FGF-23, and SOST), LPS, and phosphorous. Furthermore, transcriptome sequencing revealed that the enrichment of Acinetobacter was positively correlated with the majority of upregulated genes and negatively correlated with downregulated genes involved in the mineral absorption pathway. Conclusion: Our findings, for the first time, underscore that dysbiosis of symbiotic microbiota, both in the gut and blood, is involved in the progression of CKD. Particularly, the enrichment of Acinetobacter in blood emerges as a potential risk factor for CKD and its accompanying VC.

Effects of Patiromer and Sodium Zirconium Cyclosilicate on Blood Pressure in Rats with Chronic Kidney Disease.

Potassium-binders patiromer and sodium zirconium cyclosilicate (SZC) are approved to treat hyperkalaemia, which is frequently observed in chronic kidney disease (CKD). Elevated blood pressure (BP) is common in CKD, due in part to impaired sodium excretion. The effect of patiromer, which exchanges calcium for potassium and SZC, which exchanges sodium or hydrogen for potassium, on BP was assessed in a CKD rat model. Thirty-six Sprague Dawley rats with 5/6 nephrectomy were randomised to three groups (n = 12/group) to receive 4 g/kg/day patiromer or SZC, or vehicle treatment, for 8 weeks. BP was determined by radiotelemetry and urinary protein and electrolytes were measured. At Week 8, systolic BP (sBP) increased in all groups; however, patiromer led to a lower mean (standard deviation) sBP than vehicle or SZC (141 [2.9] vs 158 [5.2] or 162 [6.1] mm Hg, respectively, both p < 0.001), with no difference in sBP between vehicle and SZC (p = 0.08). Similar results were observed for diastolic BP. Serum potassium levels fell with SZC (p < 0.02), but not vehicle or patiromer. Urine potassium decreased with both patiromer and SZC versus vehicle (p < 0.01); urine sodium increased with SZC (p < 0.01); and urine calcium increased with patiromer (p < 0.01). Urine phosphorus decreased with patiromer (p < 0.01) but increased with SZC (p < 0.01). Patiromer resulted in less proteinuria than vehicle or SZC (both p < 0.017). After 8 weeks, treatment with patiromer resulted in lower BP in rats than vehicle or SZC. Further studies are needed to determine the mechanism of the differential effect of potassium binders on rat BP.

CD44 expression in renal tubular epithelial cells in the kidneys of rats with cyclosporine-induced chronic kidney disease.

Renal tubular epithelial cell (TEC) injury is the most common cause of drug-induced kidney injury (DIKI). Although TEC regeneration facilitates renal function and structural recovery following DIKI, maladaptive repair of TECs leads to irreversible fibrosis, resulting in chronic kidney disease (CKD). CD44 is specifically expressed in TECs during maladaptive repair in several types of rat CKD models. In this study, we investigated CD44 expression and its role in renal fibrogenesis in a cyclosporine (CyA) rat model of CKD. Seven-week-old male Sprague-Dawley rats fed a low-salt diet were subcutaneously administered CyA (0, 15, or 30 mg/kg) for 28 days. CD44 was expressed in atrophic, dilated, and hypertrophic TECs in the fibrotic lesions of the CyA groups. These TECs were collected by laser microdissection and evaluated by microarray analysis. Gene ontology analysis suggested that these TECs have a mesenchymal phenotype, and pathway analysis identified CD44 as an upstream regulator of fibrosis-related genes, including fibronectin 1 (Fn1). Immunohistochemistry revealed that epithelial and mesenchymal markers of TECs of fibrotic lesions were downregulated and upregulated, respectively, and that these TECs were surrounded by a thickened basement membrane. In situ hybridization revealed an increase in Fn1 mRNA in the cytoplasm of TECs of fibrotic lesions, whereas fibronectin protein was localized in the stroma surrounding these tubules. Enzyme-linked immunosorbent assay revealed increased serum CD44 levels in CyA-treated rats. Collectively, these findings suggest that CD44 contributes to renal fibrosis by inducing fibronectin secretion in TECs exhibiting partial epithelial-mesenchymal transition and highlight the potential of CD44 as a biomarker of renal fibrosis.

The Dietary Fiber Inulin Slows Progression of Chronic Kidney Disease-Mineral Bone Disorder (CKD-MBD) in a Rat Model of CKD.

Chronic kidney disease (CKD)-mineral bone disorder (CKD-MBD) leads to fractures and cardiovascular disease. Observational studies suggest beneficial effects of dietary fiber on both bone and cardiovascular outcomes, but the effect of fiber on CKD-MBD is unknown. To determine the effect of fiber on CKD-MBD, we fed the Cy/+ rat with progressive CKD a casein-based diet of 0.7% phosphate with 10% inulin (fermentable fiber) or cellulose (non-fermentable fiber) from 22 weeks to either 30 or 32 weeks of age (~30% and ~15% of normal kidney function; CKD 4 and 5). We assessed CKD-MBD end points of biochemistry, bone quantity and quality, cardiovascular health, and cecal microbiota and serum gut-derived uremic toxins. Results were analyzed by two-way analysis of variance (ANOVA) to evaluate the main effects of CKD stage and inulin, and their interaction. The results showed that in CKD animals, inulin did not alter kidney function but reduced the increase from stage 4 to 5 in serum levels of phosphate and parathyroid hormone, but not fibroblast growth factor-23 (FGF23). Bone turnover and cortical bone parameters were similarly improved but mechanical properties were not altered. Inulin slowed progression of aorta and cardiac calcification, left ventricular mass index, and fibrosis. To understand the mechanism, we assessed intestinal microbiota and found changes in alpha and beta diversity and significant changes in several taxa with inulin, together with a reduction in circulating gut derived uremic toxins such as indoxyl sulfate and short-chain fatty acids. In conclusion, the addition of the fermentable fiber inulin to the diet of CKD rats led to a slowed progression of CKD-MBD without affecting kidney function, likely mediated by changes in the gut microbiota composition and lowered gut-derived uremic toxins. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Effects of cerium oxide nanoparticles on adenine-induced chronic kidney disease model rats.

Cerium oxide, particularly in nanoparticle form (nanoceria), has been investigated for biomedical applications as a promising new agent for treating several pathologies. The aim of the present study was to characterize the pharmacologic effects of nanoceria in an animal model of chronic kidney disease. We created the chronic kidney disease animal model by feeding rats a 0.25% adenine diet. Male Wistar rats were divided into five groups: normal diet, 0.25% adenine diet, or adenine diet containing three different doses or durations of nanoceria treatment. Blood was collected weekly from the tail veins of each rat and analyzed for renal function markers. After 5 weeks, various biochemical markers in serum, plasma, and urine were also analyzed. In the adenine-treated group, body weight was significantly decreased, and the kidneys lost much of their healthy reddish color and became lumpy and white in appearance. In addition, levels of serum creatinine, blood urea nitrogen, and plasma uremic toxins were significantly increased in adenine-treated rats compared with controls. Renal functional and structural damage in adenine diet model rats tended to be ameliorated by nanoceria ingestion. The high-dose cerium-treated group maintained reddish areas in the kidneys, and the increases in biomarker levels of creatinine, blood urea nitrogen, and inorganic phosphorus were markedly reduced, regardless of treatment duration. Ingestion of nanoceria may be effective for improving or preventing renal damage caused by adenine. Geriatr Gerontol Int 2024; 24: 88-95.

Effects Of Quercetin and Vitamin D3 on Klotho Gene Expression in Relation to Neurological Functions in Chronic Kidney Disease Rat Model

Effects Of Quercetin and Vitamin D3 on Klotho Gene Expression in Relation to Neurological Functions in Chronic Kidney Disease Rat Model

Effects of bisphosphonates and treadmill exercise on bone and kidney in adenine-induced chronic kidney disease rats.

The increasing prevalence of osteoporosis and chronic kidney disease (CKD) due to the aging of society has highlighted the need for development of effective treatments for elderly patients. This study examined whether the combination of treadmill exercise therapy and alendronate (ALN) can improve bone mineral density (BMD) and bone strength without worsening renal function in adenine-induced CKD model rats. 8-week-old male Wistar rats (n = 70) were divided into experimental groups based on the treatment protocol, i.e., non-CKD (control), vehicle only (CKD), ALN only, exercise only, and combined ALN plus exercise. A 0.75% adenine diet was used to induce CKD. Groups were killed at either 20 or 30weeks of age. Comprehensive assessments included serum and urine biochemistry tests, renal histology, bone histomorphometry, BMD measurement, micro-computed tomography examinations, and biomechanical testing. Blood biochemistry tests, urine analyses and histological evaluations of the kidney demonstrated that ALN treatment did not worsen renal function or kidney fibrosis in moderate-stage CKD model rats. Both ALN and treadmill exercise significantly suppressed bone resorption (p < 0.05-p < 0.01). Moreover, ALN monotherapy and combined ALN and treadmill exercise significantly improved BMD of the lumbar spine and femur, bone microstructure, and trabecular bone strength (p < 0.05-p < 0.01). Treadmill exercise was also shown to decrease cortical porosity at the mid-diaphysis of the femur and improve kidney fibrosis. The combination of ALN and treadmill exercise is effective in improving BMD, the microstructure of trabecular and cortical bone, and bone strength, without compromising renal function in adenine-induced CKD model rats.

Role of CD44 expressed in renal tubules during maladaptive repair in renal fibrogenesis in an allopurinol-induced rat model of chronic kidney disease.

The kidney is a major target organ for the adverse effects of pharmaceuticals; renal tubular epithelial cells (TECs) are particularly vulnerable to drug-induced toxicity. TECs have regenerative capacity; however, maladaptive repair of TECs after injury leads to renal fibrosis, resulting in chronic kidney disease (CKD). We previously reported the specific expression of CD44 in failed-repair TECs of rat CKD model induced by ischemia reperfusion injury. Here, we investigated the pathophysiological role of CD44 in renal fibrogenesis in allopurinol-treated rat CKD model. Dilated or atrophic TECs expressing CD44 in fibrotic areas were collected by laser microdissection and subjected to microarray analysis. Gene ontology showed that extracellular matrix (ECM)-related genes were upregulated and differentiation-related genes were downregulated in dilated/atrophic TECs. Ingenuity Pathway Analysis identified CD44 as an upstream regulator of fibrosis-related genes, including Fn1, which encodes fibronectin. Immunohistochemistry demonstrated that dilated/atrophic TECs expressing CD44 showed decreases in differentiation markers of TECs and clear expression of mesenchymal markers during basement membrane attachment. In situ hybridization revealed an increase in Fn1 mRNA in the cytoplasm of dilated/atrophic TECs, whereas fibronectin was localized in the stroma around these TECs, supporting the production/secretion of ECM by dilated/atrophic TECs. Overall, these data indicated that dilated/atrophic TECs underwent a partial epithelial-mesenchymal transition (pEMT) and that CD44 promoted renal fibrogenesis via induction of ECM production in failed-repair TECs exhibiting pEMT. CD44 was detected in the urine and serum of APL-treated rats, which may reflect the expression of CD44 in the kidney.

Abstract 103: Combined Dapagliflozine And Eplerenone Treatment Improve Cardiorenal Function In Rats With Chronic Kidney Disease.

Background: Patients with chronic kidney disease (CKD) present higher risk of cardiovascular (CV) complications as well as renal function decline. The DAPA-CKD trial showed reduced CV events in diabetic and non-diabetic CKD patients treated with Dapagliflozine (DAPA). Mineralocorticoid Receptor Antagonists (MRAs) have shown similar beneficial effects in diabetic CKD patients (FIDELIO-CKD &amp; FIGARO-CKD trials) but impact in non-diabetic CKD patients is unkown. The aim of this study was to compare DAPA and Eplerenone (EPLE), alone or in combination on renal and CV functions in a non-diabetic rat CKD model. Methods: CKD was induced in Sprague Dawley rats by 5/6 nephrectomy. Rats were treated with DAPA (10 mg/kg/day PO), EPLE (100 mg/kg/day PO) or the combination during 3 months. Results: After 3 months kidney fibrosis is decreased in the 3 treated groups compared to untreated CKD. No changes of creatinine clearance were observed while albuminuria increased in the DAPA groups with no significant effects of EPLE. The fractional shortening and the cardiac output were not modified by the treatments (not shown). Cardiac hemodynamic was improved with reduced LV end diastolic pressure (LVEDP) in the CKD rats treated with EPLE or a combination of EPLE and DAPA while LV end diastolic pressure volume relationship (LVEDPVR) was decrease by both DAPA and EPLE and further decreased by DAPA + EPLE. Decreased cardiac perfusion was prevented with EPLE alone or with the combination. Conclusion: The use of DAPA + EPLE appears to be more effective than DAPA or EPLE alone on diastolic function in non-diabetic CKD rats while cardiac perfusion is improved by EPLE only.

Endothelial Dysfunction in Superior Mesenteric Arteries Isolated from Adenine-Induced Renal Failure in Model Rats.

Endothelial dysfunction-a hallmark of chronic kidney disease (CKD)-is one of the major risk factors for cardiovascular diseases (CVD). Imbalances in endothelium-derived relaxing factors (EDRFs) and contracting factors (EDCFs) specific to endothelial dysfunction in CKD are yet to be studied. Therefore, using adenine-treated rats-a CKD rat model-we investigated the responsiveness of superior mesenteric artery (SMA) endothelium to acetylcholine (ACh) stimulation under different experimental conditions. Nine-week-old male Wistar rats were treated daily with adenine (200 and 600 mg/kg body weight) by oral gavage, for 10 d; the two groups were named adenine-200 (200 mg/kg body weight) and adenine-600 (600 mg/kg body weight). The systolic blood pressure (measured 1-, 8-, and 15 d post-treatment) was significantly increased in the adenine-600 group compared with that in the control group; whereas that in the adenine-200 group showed only a slight increase. Moreover, in the adenine-600 group the serum creatinine and blood urea nitrogen (BUN) levels (measured at 18 d post-treatment) were significantly elevated when compared with those in control or adenine-200 groups. The ACh-mediated relaxation was slightly reduced in the adenine-200 group. The ACh- and sodium nitroprusside (SNP)-mediated relaxations were impaired in the adenine-600 group. Although no ACh-mediated contraction was observed in the presence of a nitric oxide (NO) synthase inhibitor, ACh-induced endothelium-derived hyperpolarizing factor-mediated relaxation was largely impaired in the adenine-600 mg/kg group. This study revealed that in the SMA of adenine-induced CKD model rats, EDCF signaling remained unaltered while the NO and EDHF signaling were impaired.