Chronic Kidney Disease Rats Research Articles

Psyllium seed husk regulates the gut microbiota and improves mucosal barrier injury in the colon to attenuate renal injury in 5/6 nephrectomy rats

Chronic kidney disease (CKD) can cause gut microbiota dysbiosis and thus impair intestinal barrier function. Disruption of intestinal homeostasis facilitates the production of enterogenic toxins, which exacerbate CKD-induced uremic toxicity and inflammation. Dietary fiber, by targeting the gut–kidney axis, could be used for CKD treatment. Psyllium seed husk (PSH) extracted from the seeds of Plantago ovata contains highly branched, gel-forming arabinoxylan. Positive effects of PSH on host physiology have been demonstrated but whether it also acts on the microbial ecosystem in CKD patients is unknown. In this study, the effects of dietary PSH on the gut microbiota, intestinal barrier function, systemic inflammation, uremic toxins, and renal injury were investigated in 5/6 nephrectomy (5/6Nx) CKD rats. Blood, feces, and kidney and colon tissues were collected from PSH-treated and control rats and subjected to biochemical and histological analyses, enzyme-linked immunosorbent assays, and 16SrRNA sequencing. PSH supplementation reduced serum creatinine and blood urea nitrogen levels, and attenuated renal tubular interstitial injury, in 5/6Nx rats. 16SrRNA sequencing showed that PSH improved the gut microbiota and intestinal barrier function in addition to down-regulating serum interleukin (IL)-1, IL-6, and indoxyl sulfate levels. Together, these results demonstrate the potential of PSH supplementation for treating CKD, including by improving intestinal microecology, reducing uremic toxin levels and systemic inflammation, and delaying disease progression.

Noninvasive Assessment of Renal Fibrosis of Chronic Kidney Disease in Rats by [68Ga]Ga-FAPI-04 Small Animal PET/CT and Biomarkers

Renal fibrosis is the most common pathological feature and common pathway of progression in chronic kidney disease (CKD). We evaluated [68Ga]Ga-FAPI-04 small animal positron emission tomography/computed tomography (PET/CT) and biomarkers as noninvasive assessments of renal fibrosis (RF) in CKD rats to generate new ideas for clinical diagnosis. A rat model of renal fibrosis was administered adenine by gavage (n = 28), and the control group was given 0.9% NaCl by gavage (n = 20). At different time points (weeks 1, 2, 4, and 6), five rats were randomly selected from the two groups for [68Ga]Ga-FAPI-04 small animal PET/CT imaging. At the same time, the expression of Fibroblast activation protein (FAP) in renal tissue and the expression levels of type III procollagen N-terminal peptide (PIIINP), transforming growth factor (TGF-β1), Klotho, and sex-determining region Y-box protein 9 (SOX9) in blood and urine were determined. FAP was highly expressed in the renal tissue of rats in the CKD group and expression increased with the progression of renal fibrosis. [68Ga]Ga-FAPI-04 small animal PET/CT examination showed that the uptake of radioactive tracers in the CKD group was higher than that in the control group, and SUVmax (r = 0.9405) and target-to-background ratio (TBR) (r = 0.9392) were positively correlated with renal fibrosis. The serum levels of PIIINP, TGF-β1, and SOX9 in CKD rats were significantly higher than those in the control group and were positively correlated with RF (r = 0.8234, r = 0.7733, and r = 0.7135, respectively) and SUVmax (r = 0.8412, r = 0.7763, and r = 0.6814, respectively). Compared with the control group, the level of serum Klotho decreased and was negatively correlated with RF (r = -0.6925) and SUVmax (r = -0.6322). Compared with the control group, the levels of PIIINP and TGF-β1 in urine were positively correlated with RF (r = 0.8127 and r = 0.8077, respectively) and SUVmax (r = 0.8400 and r = 0.8177, respectively). Urine Klotho decreased compared with the control group and was negatively correlated with RF (r = -0.5919) and SUVmax (r = -0.5995). The change in urine SOX9 was not statistically significant. In conclusion, compared with renal biopsy, [68Ga]Ga-FAPI-04 small animal PET/CT shows renal fibrosis quickly and noninvasively. PIIINP, TGF-β1, and Klotho in serum and urine may be used as biomarkers of RF, and serum SOX9 is expected to become a new diagnostic biomarker of RF.

Cardiac remodeling associated with chronic kidney disease is enhanced in a rat model of metabolic syndrome: Preparation of mesenchymal transition.

Cardiac alteration due to chronic kidney disease is described by tissue fibrosis. This remodeling involves myofibroblasts of various origins, including epithelial or endothelial to mesenchymal transitions. In addition, obesity and insulin resistance together or separately seem to exacerbate cardiovascular risk in chronic kidney disease (CKD). The main objective of this study was to assess if pre-existing metabolic disease exacerbates CKD-induced cardiac alterations. In addition, we hypothesised that endothelial to mesenchymal transition participates in this enhancement of cardiac fibrosis. Rats fed cafeteria type diet for 6months underwent a subtotal nephrectomy at 4months. Cardiac fibrosis was evaluated by histology and qRT-PCR. Collagens and macrophages were quantified by immunohistochemistry. Endothelial to mesenchymal transitions were assessed by qRT-PCR (CD31, VE-cadherin, α-SMA, nestin) and also by CD31 immunofluorescence staining. Rats fed with cafeteria type regimen were obese, hypertensive and insulin resistant. Cardiac fibrosis was predominant in CKD rats and was highly majored by cafeteria regimen. Collagen-1 and nestin expressions were higher in CKD rats, independently of regimen. Interestingly, in rats with CKD and cafeteria diet we found an increase of CD31 and α-SMA co-staining with suggest an implication of endothelial to mesenchymal transition during heart fibrosis. We showed that rats already obese and insulin resistant had an enhanced cardiac alteration to a subsequent renal injury. Cardiac fibrosis process could be supported by a involvement of the endothelial to mesenchymal transition phenomenon.

Bupi Yishen formula may prevent kidney fibrosis by modulating fatty acid metabolism in renal tubules

BackgroundBupi Yishen formula (BYF), a traditional Chinese herbal mixture, has demonstrated better effectiveness than Losartan in preserving renal function and preventing composite severe adverse outcomes in patients with advanced chronic kidney disease (CKD) in a recent randomized controlled trial. Prior studies have shown that BYF exerts anti-inflammatory and anti-fibrotic effects in the kidneys of CKD models, but the underlying mechanisms have not been fully elucidated. PurposeThe aim of this study was to investigate the protective effects of BYF administration on profibrotic phenotypic changes in the kidney and to elucidate its fundamental mechanisms of action. MethodsAdenine and 5/6 nephrectomy rat models were administered with two doses of BYF extract (15 or 30 g/kg/d) by intragastric administration, and Losartan treatment was used as a positive control group. The relationship between BYF renoprotection and restoration of fatty acid dysregulation was examined using the two fibrosis models and TGFb1-induced human tubular HK2 cells. Transcriptomic profiles of the fibrotic kidneys obtained from adenine-induced CKD rats were used to identify the key mechanisms that are affected by BYF intervention. Human relevance and clinical implications were established by re-analysis of the microarray databases of CKD patients and immunostaining on human biopsy specimens. ResultsBYF effectively prevented kidney histological damage and ameliorated renal malfunction in the adenine rat model of CKD. BYF robustly attenuated the significant increase in profibrotic and proapoptotic markers in fibrotic kidneys of adenine-induced CKD rats. Transcriptomic analyses of the fibrotic kidneys of the adenine rats identified fatty acid metabolism as the key dysregulated pathway affected by BYF prevention. BYF significantly reversed defective fatty acid oxidation (FAO) and the intracellular lipids accumulation in the fibrotic kidneys induced by 5/6 nephrectomy. Furthermore, BYF prevented dysfunctional fatty acid metabolism, which were associated with the significant improvement of TGFb1-induced profibrotic changes in HK2 human proximal tubular cells. Furthermore, analyses of kidney microarray databases and biopsy specimens of CKD patients suggested that FAO defect is common in CKD in humans. ConclusionOur exploratory study found that BYF may exert protective effects on renal fibrosis by regulating the fatty acid metabolism of renal tubular cells, which may be a key mechanism for preventing kidney fibrosis in CKD.

Altered Lung Heat Shock Protein-70 Expression and Severity of Sepsis-Induced Acute Lung Injury in a Chronic Kidney Disease Rat Model

Enhanced heat shock protein-70 (HSP-70) expression in the lungs is associated with attenuated acute lung injury (ALI) in a sepsis model. Chronic kidney disease (CKD) significantly contributes to the poor prognosis of patients with sepsis. This study examined the relationship between sepsis-induced ALI severity and altered lung HSP-70 expression in CKD. Experimental rats underwent a sham operation (control group) or 5/6 nephrectomy (CKD group). Sepsis was induced with cecal ligation and puncture (CLP). Laboratory tests and lung harvest were performed in the control group (without CLP and after 3, 12, 24, and 72 h of CLP) and in the CKD group (without CLP and after 72 h of CLP). ALI was the most severe after 12 h of sepsis. The mean lung injury score at 72 h after sepsis was significantly higher in the CKD group than in the control group (4.38 versus 3.30, p < 0.01). Nonetheless, enhanced lung HSP-70 expression was not observed in the CKD group. This study shows that altered lung HSP-70 expression is associated with the worsening of sepsis-induced ALI in patients with CKD. Enhancing lung HSP-70 is a novel treatment target for patients with CKD and sepsis-induced ALI.

Magnesium Improves Cardiac Function in Experimental Uremia by Altering Cardiac Elastin Protein Content.

Cardiovascular complications are accompanied by life-threatening complications and represent the major cause of death in patients with chronic kidney disease (CKD). Magnesium is important for the physiology of cardiac function, and its deficiency is common in CKD. In the present study, we investigated the impact of oral magnesium carbonate supplementation on cardiac function in an experimental model of CKD induced in Wistar rats by an adenine diet. Echocardiographic analyses revealed restoration of impaired left ventricular cardiac function in animals with CKD. Cardiac histology and real-time PCR confirmed a high amount of elastin protein and increased collagen III expression in CKD rats supplemented with dietary magnesium as compared with CKD controls. Both structural proteins are crucial in maintaining cardiac health and physiology. Aortic calcium content increased in CKD as compared with tissue from control animals. Magnesium supplementation numerically lowered the increases in aortic calcium content as it remained statistically unchanged, compared with controls. In summary, the present study provides evidence for an improvement in cardiovascular function and aortic wall integrity in a rat model of CKD by magnesium, as evidenced by echocardiography and histology.

VX-765 ameliorates CKD VSMC calcification by regulating STAT3 activation

BackgroundRecent clinical evidences show that caspase-1 inhibitor-VX-765 attenuates atherosclerosis in ApoE deficient mice. However, there is rarely information about the effect of VX-765 on hyperphosphatemia-induced vascular smooth muscle cells (VSMCs) calcification or vascular calcification in chronic kidney disease (CKD) rats. Here we investigate the effect of VX-765 on vascular calcification in uremia circumstances. MethodsHyperphosphatemia-induced VSMC calcification were evaluated by Alizarin Red S. Aortas from CKD rats which were gavaged with VX-765 were examined for calcification signal using micro-CT. Levels of NLRP3, caspase-1, and GSDMD were measured by quantitative real-time PCR, western blotting, immunofluorescence assay, and immunohistochemistry. ResultsWe demonstrated for the first time that the levels of NLRP3, caspase-1, GSDMD, IL-1β, and IL-18 were up-regulated in hyperphosphatemia-induced calcifying VSMCs. Blockade of caspase-1 activation by VX-765 inhibited pyroptosis-related molecules and VSMC calcification in a concentration-dependent manner in vitro. Further analysis of aortas from calcified CKD rats showed an up-regulation of caspase-1 and GSDMD expression compared with those non-calcified vascular tissue from control rats or with those decreased-calcified vascular tissue from CKD rats treated with 50 mg/kg/d, which indicated that pyroptotic indicators were tightly correlated with CKD arterial calcification. In vitro studies further demonstrated that VX-765 ameliorated hyperphosphatemia-induced VSMCs calcification through inhibiting the STAT3 activation. ConclusionsOur findings indicated that VX-765 could inhibit hyperphosphatemia-induced calcifying VSMCs and ameliorate vascular calcification in CKD rats. VX-765 might be a potential treatment strategy for CKD vascular calcification.

PRE-084 ameliorated kidney injury by reducing endoplasmic reticulum stress in the rat model of adenine-induced chronic kidney disease.

Endoplasmic reticulum (ER) stress plays an important role in the development of chronic kidney disease (CKD). Sigma-1 receptors (σ1Rs) are novel chaperone proteins that regulate ER stress. However, effect of σ1R activation on renal ER stress is yet unexplored. So, in the present study we investigated the effects of PRE-084, aσ1R agonist on renal injury and ER stress in the rat model of CKD. CKD group rats were fed adenine for 28 days and CKD treatment group rats were additionally administered PRE-084 intraperitoneally at 1, 3 and 10mg/kg body weight dose from Day 22-28. ER stress markers were evaluated using molecular biology techniques such as immunohistochemistry and Western blot. Marked kidney injury was observed in CKD rats as revealed by biochemical and histological findings. Expression of ER stress proteins such as phosphorylated protein kinase R-like ER kinase (p-PERK), cleaved activating transcription factor-6 (ATF-6f), phosphorylated inositol requiring enzyme1α (p-IRE1α) and caspase-12 were higher in CKD rats. Nevertheless, CKD rats treated with PRE-084 particularly at 10mg/kg dose showed considerably lesser kidney injury along with higher expression of σ1R and marked reduction of all the ER stress proteins studied. Results reveal that PRE-084 likely ameliorated the adenine-induced kidney injury by lowering ER stress through increased σ1R expression.

Sodium thiosulfate through preserving mitochondrial dynamics ameliorates oxidative stress induced renal apoptosis and ferroptosis in 5/6 nephrectomized rats with chronic kidney diseases.

Chronic kidney disease (CKD) progression may be evoked through dysregulated mitochondrial dynamics enhanced oxidative stress and inflammation contributing to high cardiovascular morbidity and mortality. Previous study has demonstrated sodium thiosulfate (STS, Na2S2O3) could effectively attenuate renal oxidative injury in the animal model of renovascular hypertension. We explored whether the potentially therapeutic effect of STS is available on the attenuating CKD injury in thirty-six male Wistar rats with 5/6 nephrectomy. We determined the STS effect on reactive oxygen species (ROS) amount in vitro and in vivo by an ultrasensitive chemiluminescence-amplification method, ED-1 mediated inflammation, Masson's trichrome stained fibrosis, mitochondrial dynamics (fission and fusion) and two types of programmed cell death, apoptosis and ferroptosis by western blot and immunohistochemistry. Our in vitro data showed STS displayed the strongest scavenging ROS activity at the dosage of 0.1 g. We applied STS at 0.1 g/kg intraperitoneally 5 times/week for 4 weeks to these CKD rats. CKD significantly enhanced the degree in arterial blood pressure, urinary protein, BUN, creatinine, blood and kidney ROS amount, leukocytes infiltration, renal 4-HNE expression, fibrosis, dynamin-related protein 1 (Drp1) mediated mitochondrial fission, Bax/c-caspase 9/c-caspase 3/poly (ADP-ribose) polymerase (PARP) mediated apoptosis, iron overload/ferroptosis and the decreased xCT/GPX4 expression and OPA-1 mediated mitochondrial fusion. STS treatment significantly ameliorated oxidative stress, leukocyte infiltration, fibrosis, apoptosis and ferroptosis and improved mitochondrial dynamics and renal dysfunction in CKD rats. Our results suggest that STS as drug repurposing strategy could attenuate CKD injury through the action of anti-mitochondrial fission, anti-inflammation, anti-fibrosis, anti-apoptotic, and anti-ferroptotic mechanisms.

High-intensity interval training using electrical stimulation improves mitochondrial dysfunction and muscle endurance in rats with chronic kidney disease.

Mitochondrial dysfunction in skeletal muscle has recently been highlighted as a major pathophysiological factor of chronic kidney disease (CKD)-associated muscle fatigue. However, effective therapeutic interventions to improve mitochondrial function have not been established. Here we examined the effects of high-intensity interval training (HIIT) using electrical stimulation (ES) intervention on skeletal muscle in CKD rats. CKD was induced by 5/6 nephrectomy (Nx) in male Wistar rats, and sham-operated rats served as controls (Sham). We defined the left leg of Nx rat trained with HIIT as the Nx-HIIT leg and the untrained right leg as the Nx-CNT leg. HIIT was enforced by electrically stimulating plantar flexor muscles every other day for 4 weeks. In vivo muscle endurance analysis using repeated fatiguing stimulation measured 24 h after the last training session showed a significantly greater force depression in the Nx-CNT leg compared to that in the Sham leg, which was significantly improved in the Nx-HIIT leg. Pyruvate/malate-driven ADP- and uncoupler-stimulated mitochondrial respiration in isolated muscle mitochondria from the Nx-CNT leg assessed by Seahorse XFe96 analyzer were significantly decreased compared with those from the Sham leg, which were also significantly recovered in those of the Nx-HIIT leg. Consistent with improved mitochondrial function, myosin heavy chain (MyHC) electrophoresis showed a significant increase in the proportion of fast-twitch MyHC IIB fibers in the Nx-CNT leg compared to that in the Sham and the Nx-HIIT leg. HIIT with ES improved muscle fatigue and mitochondrial function in a rat model of CKD-associated cachexia. HIIT with ES may lead to an innovative therapeutic intervention that can be utilized for patients with CKD-associated cachexia who have difficulty with full-body exercise.

Upacicalcet, a positive allosteric modulator of the calcium-sensing receptor, prevents vascular calcification and bone disorder in a rat adenine-induced secondary hyperparathyroidism model.

Secondary hyperparathyroidism (SHPT) is a major comorbidity of chronic kidney disease (CKD). Chronic elevation of PTH levels is associated with cortical bone deterioration and increase in the risk of fractures in CKD patients. Here, we evaluated the effect of repeated administration of upacicalcet, a novel positive allosteric modulator of the calcium-sensing receptor, in a rat model of adenine-induced renal failure, by determining serum levels of intact PTH (iPTH), calcium, phosphorus, creatinine, and urea nitrogen. Furthermore, parathyroid hyperplasia (parathyroid gland weight and Ki-67-positive cell density), ectopic calcification (calcium content in the thoracic aorta, kidney and heart and positive von Kossa staining in the thoracic aorta), and bone morphometry parameters (cortical porosity and fibrosis volume) were evaluated. Rats treated with either 0.2mg/kg or 1mg/kg upacicalcet exhibited significantly lower serum iPTH levels than CKD-control rats, as early as 7days after the first dose. Repeated administration of upacicalcet reduced serum iPTH levels and inhibited parathyroid hyperplasia in rats with adenine-induced severe renal failure. Moreover, it suppressed ectopic calcification and cortical pore formation. In contrast, serum calcium and phosphorus levels were not significantly affected, suggesting a low risk of hypocalcemia, which often occurs with SHPT treatment. In conclusion, repeated administration of upacicalcet decreased serum iPTH levels and suppressed parathyroid hyperplasia in the adenine-induced CKD rat model of SHPT. Furthermore, ectopic calcification and cortical pore formation were suppressed without significant changes in blood mineral parameters. Upacicalcet safely inhibited the progression of SHPT in an adenine-induced CKD rat model.

Salt-induced phosphoproteomic changes in the subfornical organ in rats with chronic kidney disease

Objectives Subfornical organ (SFO) is vital in chronic kidney disease (CKD) progression caused by high salt levels. The current study investigated the effects of high salt on phosphoproteomic changes in SFO in CKD rats. Methods 5/6 nephrectomized rats were fed a normal-salt diet (0.4%) (NC group) or a high-salt diet (4%) (HC group) for three weeks, while sham-operated rats were fed a normal-salt diet (0.4%) (NS group). For phosphoproteomic analysis of SFO in different groups, TiO2 enrichment, isobaric tags for relative and absolute quantification (iTRAQ) labeling, and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used. Results There were 6808 distinct phosphopeptides found, which corresponded to 2661 phosphoproteins. NC group had 168 upregulated and 250 downregulated phosphopeptides compared to NS group. Comparison to NC group, HC group had 154 upregulated and 124 downregulated phosphopeptides. Growth associated protein 43 (GAP43) and heat shock protein 27 (Hsp27) were significantly upregulated phosphoproteins and may protect against high-salt damage. Differential phosphoproteins with tight functional connection were synapse proteins and microtubule-associated proteins, implying that high-salt diet disrupted brain’s structure and function. Furthermore, differential phosphoproteins in HC/NC comparison group were annotated to participate in GABAergic synapse signaling pathway and aldosterone synthesis and secretion, which attenuated inhibitory neurotransmitter effects and increased sympathetic nerve activity (SNA). Discussion This large scale phosphoproteomic profiling of SFO sheds light on how salt aggravates CKD via the central nervous system.

Dietary Resveratrol Butyrate Monoester Supplement Improves Hypertension and Kidney Dysfunction in a Young Rat Chronic Kidney Disease Model.

Chronic kidney disease (CKD) remains a public health problem. Certain dietary supplements can assist in the prevention of CKD progression. In this regard, resveratrol is a polyphenol and has a potential therapeutic role in alleviating CKD. We previously utilized butyrate in order to improve the bioavailability of resveratrol via esterification and generated a resveratrol butyrate monoester (RBM). In this study, the hypothesis that RBM supplementation is able to protect against kidney dysfunction and hypertension was tested by using an adenine-induced CKD model. For this purpose, three-week-old male Sprague Dawley rats (n = 40) were equally categorized into: group 1-CN (sham control); group 2-CKD (adenine-fed rats); group 3-REV (CKD rats treated with 50 mg/L resveratrol); group 4-MEL (CKD rats treated with 25 mg/L RBM); and group 5-MEH (CKD rats treated with 50 mg/L RBM). At the end of a 12-week period, the rats were then euthanized. The adenine-fed rats displayed hypertension and kidney dysfunction, which were attenuated by dietary supplementation with RBM. The CKD-induced hypertension coincided with: decreased nitric oxide (NO) bioavailability; augmented renal protein expression of a (pro)renin receptor and angiotensin II type 1 receptor; and increased oxidative stress damage. Additionally, RBM and resveratrol supplementation shaped distinct gut microbiota profiles in the adenine-treated CKD rats. The positive effect of high-dose RBM was shown together with an increased abundance of the genera Duncaniella, Ligilactobacillus, and Monoglobus, as well as a decrease in Eubacterium and Schaedierella. Importantly, the mechanism of action of the RBM supplementation may be related to the restoration of NO, rebalancing of the RAS, a reduction in oxidative stress, and alterations to the gut microbiota. Moreover, RBM supplementation shows promise for the purposes of improving CKD outcomes and hypertension. As such, further translation to human studies is warranted.

Chronic kidney disease to osteoporosis: histopathological analysis on animal model with unilateral ureteral obstruction method

Background: One of the most frequent complications due to the progression of chronic kidney disease (CKD) is the occurrence of disturbances in mineral metabolism.. Increased bone remodeling results in osteopenia, which can progressively lead to osteoporosis. Wistar albino rats (Rattus norvegicus) are one of the most well-known and easy-to-obtain laboratory test animals. Data regarding the duration of bone pathological progression in CKD-induced Wistar strain rats by the unilateral ureteral obstruction method are limited. Methods: This was a descriptive observational study, with a prospective cohort approach. The aim was to determine the histopathological onset of osteoporosis in Wistar rats with the CKD model. We used 13 male Wistar rats (Rattus norvegicus). The CKD rat models were randomized and put into four containers, each containing three rats. Each group was treated in the same way for predetermined durations, which were the 7th day, 14th day, 21st day, and 28th day after CKD modeling, before being sacrificed for femoral bone histopathological collection. Results: On the 7th day after CKD modeling, we discovered thickening of the periosteal fibrous tissue. On the 14th and 21st days, there was an increase in the thickness of the periosteal fibrous tissue in the metaphyseal and diaphyseal areas. This thickening progression was in line with the length of treatment time. On the 21st day, we began to see the increasing gap between the trabecular tissues. On the 28th day, the histopathological analysis of femoral bone tissue showed thinning of the bone trabecular tissue and the most distant inter-trabecular spaces, suggesting the appearance of osteoporosis. Conclusion: The histopathological picture of osteoporosis in the Wistar strain rat model of CKD appeared most clearly and worst on the 28th day after CKD. It was marked by the thinning of the trabecular bone tissue and the most distant spaces between the trabeculae.

Bone marrow mesenchymal stem cells inhibit ferroptosis via regulating the Nrf2-keap1/p53 pathway to ameliorate chronic kidney disease injury in the rats

Purpose Although bone marrow mesenchymal stem cells (BMMSCs) have been reported to exhibit a protective effect on animal models of chronic kidney disease (CKD), the exact mechanisms involved require further investigation. This study aims to investigate the underlying molecular mechanisms of BMMSCs in inhibiting ferroptosis and preventing an Adriamycin (ADR)-induced CKD injury. Methods A rat model of long-term CKD induced through the injection of ADR administered twice weekly via the tail vein was used in this study. After BMMSCs were systemically administered through the renal artery, pathological staining, western blotting, ELISA, and transmission electron microscopy were used to analyze ferroptosis. Results Analyses of renal function and histopathological findings indicated that ADR-mediated renal dysfunction improved in response to the BMMSC treatment, which was also sufficient to mediate the partial reversal of renal injury and mitochondrial pathological changes. BMMSCs decreased the ferrous iron (Fe2+) and reactive oxygen species and elevated glutathione (GSH) and GSH peroxidase 4. Moreover, the BMMSC treatment activated the expression of ferroptosis-related regulator NF-E2-related factor 2 (Nrf2) and inhibited Keap1 and p53 in CKD rat kidney tissues. Conclusions BMMSCs alleviate CKD, possibly resulting from the inhibition of kidney ferroptosis by regulating the Nrf2–Keap1/p53 pathway.

Effect of Uremic Clearance Granules on improvement of chronic kidney disease in rats based on microbiome-metabolomics and its mechanism

This research aimed to study the effect of Uremic Clearance Granules on chronic kidney disease in SD rats by using the methods of microbial functional genomics combined with metabolomics, and to preliminarily explore its mechanism. The SD rat model of chronic kidney disease was established by the adenine-induced method. After the model was successfully induced, the animals were randomly divided into a negative control group, a Uremic Clearance Granule treatment group, and a normal control group, with 8 rats in each group. After 4 weeks of administration, animal feces and serum were collected, and 16S rDNA sequencing technology was used to analyze the abundance, diversity, and function prediction of intestinal microorganisms. Liquid chromatography-mass spectrometry(LC-MS) technology was used to perform high-throughput sequencing to detect animal serum metabolites. The MetPA database was used to screen out potential biomarkers of chronic kidney disease in rats and conduct the enrichment analysis of metabolic pathways. Spearman's method was used to analyze the correlation between the two omics. The results showed that Uremic Clearance Granules effectively improved the body weight loss and renal function-related biochemical and appearance indicators in rats with chronic kidney disease. The results of 16S rDNA sequencing showed that Uremic Clearance Granules regulated the diversity and composition of the intestinal flora in rats with chronic kidney disease. The changes in the intestinal flora affected functional metabolic pathways such as amino acid biosynthesis and metabolism, lipid metabolism, and carbohydrate metabolism. The results of LC-MS showed that as compared with the negative control group, 15 metabolites were reversed in the Uremic Clearance Granule treatment group, among which 11 potential marker metabolites were significantly up-regulated and 4 potential marker metabolites were significantly down-regulated. Five amino acid metabolic pathways were mainly involved, which were significantly correlated with changes in the intestinal flora. Therefore, Uremic Clearance Granules can improve the renal function of rats with chronic kidney disease, and the mechanism may be related to its effect on the amino acid metabolism pathway by regulating the intestinal flora.

Akkermansia muciniphila ameliorates chronic kidney disease interstitial fibrosis via the gut-renal axis.

Chronic kidney disease (CKD) affects approximately 10% of the global population. The abundance of Akkermansia muciniphila (AKK) is significantly reduced in CKD patients. This study investigated the effects of AKK bacteria on kidney damage and the renal interstitium in rats with CKD. CKD model 5/6 nephrectomy rats were used. CKD rats were supplemented with AKK (2×108cfu/0.2mL) for 8 weeks. AKK administration significantly suppressed epithelial-mesenchymal transition (EMT), and high-throughput 16S rRNA pyrosequencing showed that AKK supplementation restored the disordered intestinal microecology in CKD rats. AKK also enhanced the intestinal mucosal barrier function. AKK may regulate the intestinal microecology and reduce renal interstitial fibrosis by enhancing the abundance of probiotics and reducing damage to the intestinal mucosal barrier. The results suggest that AKK administration could be a novel therapeutic strategy for treating renal fibrosis and CKD.

Vascular Calcification Exacerbates Abnormal Blood Pressure Variability in Chronic Kidney Disease: A “Two-Step” Study in Rats

Introduction: Vascular calcification (VC) is a common complication of chronic kidney disease (CKD) with poor cardiovascular prognosis. The aim of this study was to explore the impact of VC on blood pressure variability (BPV) in animal models of CKD. Methods: Two optimal modelling methods, adenine high-phosphorus (HP) diet + calcitriol and 5/6 nephrectomy (Nx) + HP diet + calcitriol, for CKD-VC were chosen from the first-step experiment for the next step. A total of 36 male Wistar rats were randomly assigned to the standard-chow, sham-operated, adenine, 5/6Nx, adenine-VC, and 5/6Nx-VC groups. Continuous blood pressure (BP) measurement using the BP-2000 animal noninvasive BP analyser was started at the 9th week for the standard-chow, adenine, and adenine-VC groups and at the 7th week for the sham-operated, 5/6Nx, and 5/6Nx-VC groups. BPV metrics (BPVs), including the difference between maximum and minimum values, standard deviation, coefficient of variation, average real variability, and residuals derived from the generalized linear model of BP, were calculated. Results: The first experiment showed that the use of calcitriol accelerated the progression of VC in CKD rats (the modelling period was shortened from 16 weeks to 4–8 weeks) and confirmed the occurrence of VC at weeks 8 and 6 in the adenine-VC and 5/6Nx-VC groups, respectively. In the second experiment, 13 of 20 hour-to-hour BPVs increased significantly with the development of CKD and VC. BPV differences among the standard-chow, adenine, and adenine-VC groups were mainly due to the differences between the standard-chow and adenine-VC groups (7 of 10 BPVs were significantly different), followed by the differences between the standard-chow and adenine groups (3 of 10). BPV differences among the sham-operated, 5/6Nx, and 5/6Nx-VC groups were caused by the differences between the 5/6Nx-VC and 5/6Nx groups (4 of 10) or the 5/6Nx-VC and sham-operated groups (3 of 10). Conclusion: An increased BPV is observed in CKD rats, and VC further aggravates the abnormality of BPVs independent of CKD.

Oxidized-LDL Deteriorated the Renal Residual Function and Parenchyma in CKD Rat through Upregulating Epithelial Mesenchymal Transition and Extracellular Matrix-Mediated Tubulointerstitial Fibrosis-Pharmacomodulation of Rosuvastatin.

This study tested the hypothesis that intrarenal arterial transfusion of oxidized low-density lipoprotein (ox-LDL) jeopardized the residual renal function and kidney architecture in rat chronic kidney disease ((CKD), i.e., induced by 5/6 nephrectomy) that was reversed by rosuvastatin. Cell culture was categorized into A1 (NRK-52E cells), A2 (NRK-52E + TGF-β), A3 (NRK-52E + TGF-β + ox-LDL) and A4 (NRK-52E + TGF-β + ox-LD). The result of in vitro study showed that cell viability (at 24, 48 and 72 h), NRK-52E ox-LDL-uptake, protein expressions of epithelial-mesenchymal-transition (EMT) markers (i.e., p-Smad2/snail/α-SMA/FSP1) and cell migratory and wound healing capacities were significantly progressively increased from A1 to A4 (all p &lt; 0.001). SD rats were categorized into group 1 (sham-operated control), group 2 (CKD), group 3 (CKD + ox-LDL/0.2 mg/rat at day 14 after CKD induction) and group 4 (CKD + ox-LDL-treated as group 3+ rosuvastatin/10 mg/kg/day by days 20 to 42 after CKD induction) and kidneys were harvested at day 42. The circulatory levels of BUN and creatinine, ratio of urine-protein to urine-creatinine and the protein expressions of the above-mentioned EMT, apoptotic (cleaved-caspase3/cleaved-PARP/mitochondrial-Bax) and oxidative-stress (NOX-1/NOX-2/oxidized-protein) markers were lowest in group 1, highest in group 3 and significantly higher in group 4 than in group 2 (all p &lt; 0.0001). Histopathological findings demonstrated that the kidney injury score, fibrotic area and kidney injury molecule-1 (KIM-1) displayed an identical pattern, whereas the cellular expression of podocyte components (ZO-1/synaptopodin) exhibited an opposite pattern of EMT markers (all p &lt; 0.0001). In conclusion, ox-LDL damaged the residual renal function and kidney ultrastructure in CKD mainly through augmenting oxidative stress, EMT and fibrosis that was remarkably reversed by rosuvastatin.

Identification of ferroptosis‑associated genes in chronic kidney disease.

Ferroptosis serves a pivotal role in developing chronic kidney disease (CKD). The present study aimed to detect and confirm the relevance of potential ferroptosis-related genes in CKD using bioinformatics and experimentation strategies. The original GSE15072 mRNA expression dataset was retrieved from the Gene Expression Omnibus database. Subsequently, the potential differentially expressed genes associated with ferroptosis of CKD were screened using R software. Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analyses, correlation analysis and protein-protein interactions (PPI) were performed for differentially expressed ferroptosis-associated genes (DFGs). Lastly, the expression levels of the top nine DFGs were measured in the kidney tissue of Adriamycin-induced CKD rats and healthy controls via reverse transcription-quantitative (RT-q)PCR analysis. Overall, 49 DFGs among 21 patients with CKD and nine healthy controls were identified. GO and KEGG enrichment analyses demonstrated that these DFGs were primarily involved in 'ferroptosis' and 'mitophagy'. PPI findings indicated that these ferroptosis-associated genes interacted with one another. RT-qPCR of CKD tissue from the rat model revealed that STAT3, MAPK14, heat shock protein (HSP)A5, MTOR and solute carrier family 2 member 1 (SLC2A1) mRNA levels in CKD were upregulated. Overall, 49 potential ferroptosis-associated genes of CKD were identified via bioinformatics analyses. STAT3, MAPK14, HSPA5, MTOR and SLC2A1 may influence CKD onset by regulating ferroptosis. The present results add to the existing body of knowledge about CKD and may be useful in the treatment of CKD.