Uremic mouse model to study vascular calcification and "inflamm-aging".

Calcification and chronic inflammation of the vascular wall is a high-risk factor for cardiovascular mortality, especially in patients with chronic uremia. For the reduction or prevention of rapid disease progression, no specific treatment options are currently available. This study aimed to evaluate an adenine-based uremic mouse model for studying medial vessel calcification and senescence-associated secretory phenotype (SASP) changes of aortic tissue to unravel molecular pathogenesis and provide a model for therapy testing. The dietary adenine administration induced a stable and similar degree of chronic uremia in DBA2/N mice with an increase of uremia blood markers such as blood urea nitrogen, calcium, creatinine, alkaline phosphatase, and parathyroid hormone. Also, renal fibrosis and crystal deposits were detected upon adenine feeding. The uremic condition is related to a moderate to severe medial vessel calcification and subsequent elastin disorganization. In addition, expression of osteogenic markers as Bmp-2 and its transcription factor Sox-9 as well as p21 as senescence marker were increased in uremic mice compared to controls. Pro-inflammatory uremic proteins such as serum amyloid A, interleukin (Il)-1ß, and Il-6 increased. This novel model of chronic uremia provides a simple method for investigation of signaling pathways in vascular inflammation and calcification and therefore offers an experimental basis for the development of potential therapeutic intervention studies.

[Patients with IgA nephropathy often develop terminal uraemia]. / Patienter med IgA-nefropati utvecklar ofta terminal njursvikt.

IgA nephropathy is the most common form of inflammatory kidney disease causing uraemia world-wide and initially often a silent disease with microscopic haematuria as the only clinical finding. If left untreated, progress to terminal uraemia and dialysis is not uncommon as at least 30 % develop end stage renal failure. Awareness of the existence of the disease among GPs, internists and urologists may be helpful, not disregarding microscopic haematuria, particularly in combination with albuminuria or finding of renal casts in the urine, especially in younger individuals. No diagnostic marker in blood or urine for the disease has yet been established so kidney biopsy is still needed to confirm diagnosis. The degree of renal dysfunction, hypertension, albuminuria, and histology findings at time of diagnosis have significant impact on renal outcome. Potential biomarkers for progressive disease have been described but no one has so far been implicated in clinical practice. Until now, the only evidence-based medication consists of blockers of the renin-angiotensin-system and corticosteroids. However, new and potentially more specific drugs are under clinical investigation. Early intervention is mandatory to prevent disease progression. Thus, we want to alarm other specialists to an increased alertness for this disease, referring patients at an early stage of possible IgA nephropathy to the nephrologist for diagnosis and interventions.

Omega-3 Polyunsaturated Fatty Acid Attenuates Uremia-Induced Brain Damage in Mice.

Although the cause of neurological disease in patients with chronic kidney disease (CKD) has not been completely identified yet, recent papers have identified accumulated uremic toxin as its main cause. Additionally, omega-3 polyunsaturated fatty acid (ω-3 PUFA) plays an important role in maintaining normal nerve function, but its protective effects against uremic toxin is unclear. The objective of this study was to identify brain damage caused by uremic toxicity and determine the protective effects of ω-3 PUFA against uremic toxin. We divided mice into the following groups: wild-type (wt) sham (n = 8), ω-3 PUFA sham (n = 8), Fat-1 sham (n = 8), ischemia-reperfusion (IR) (n = 20), and ω-3 PUFA+IR (n = 20) Fat-1+IR (n = 20). Brain tissue, kidney tissue, and blood were collected three days after the operation of mice (sham and IR operation). This study showed that Ki67 and neuronal nuclei (NeuN) decreased in the brain of uremic mice as compared to wt mice brain, but increased in the ω-3 PUFA-treated uremic mice and the brain of uremic Fat-1 mice as compared to the brain of uremic mice. The pro-apoptotic protein expressions were increased, whereas anti-apoptotic protein expression decreased in the brain of uremic mice as compared to wt mice brain. However, apoptotic protein expression decreased in the ω-3 PUFA-treated uremic mice and the brain of uremic Fat-1 mice as compared to the brain of uremic mice. Furthermore, the brain of ω-3 PUFA-treated uremic mice and uremic Fat-1 mice showed increased expression of p-PI3K, p-PDK1, and p-Akt as compared to the brain of uremic mice. We confirm that uremic toxin damages the brain and causes cell death. In these injuries, ω-3 PUFA plays an important role in neuroprotection through PI(3)K-Akt signaling.

Dextromethorphan Reduces Oxidative Stress and Inhibits Uremic Artery Calcification.

Medial vascular calcification has emerged as a key factor contributing to cardiovascular mortality in patients with chronic kidney disease (CKD). Vascular smooth muscle cells (VSMCs) with osteogenic transdifferentiation play a role in vascular calcification. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors reduce reactive oxygen species (ROS) production and calcified-medium-induced calcification of VSMCs. This study investigates the effects of dextromethorphan (DXM), an NADPH oxidase inhibitor, on vascular calcification. We used in vitro and in vivo studies to evaluate the effect of DXM on artery changes in the presence of hyperphosphatemia. The anti-vascular calcification effect of DXM was tested in adenine-fed Wistar rats. High-phosphate medium induced ROS production and calcification of VSMCs. DXM significantly attenuated the increase in ROS production, the decrease in ATP, and mitochondria membrane potential during the calcified-medium-induced VSMC calcification process (p < 0.05). The protective effect of DXM in calcified-medium-induced VSMC calcification was not further increased by NADPH oxidase inhibitors, indicating that NADPH oxidase mediates the effect of DXM. Furthermore, DXM decreased aortic calcification in Wistar rats with CKD. Our results suggest that treatment with DXM can attenuate vascular oxidative stress and ameliorate vascular calcification.

Uremic serum damages endothelium by provoking excessive neutrophil extracellular trap formation.

Cardiovascular disease (CVD) is the leading cause of death in patients with chronic kidney disease (CKD). Endothelial cell (EC) dysfunction is a key CKD-specific risk factor; however, the mechanisms by which uremia harms the endothelium are still unclear. We report a role for excessive neutrophil extracellular trap (NET) formation induced by uremic serum on EC injury. Level of plasma nucleosome and myeloperoxidase-DNA, established in vivo markers of NETs, as well as intracellular adhesion molecule (ICAM)-1 were measured in hemodialysis (HD) patients and healthy volunteers (HV) and their prognostic role evaluated. For in vitro studies, HV-derived neutrophils and differentiated HL-60 cells by retinoic acid were used to determine the effect of uremic serum-induced NETs on human umbilical vein EC (HUVEC). The level of in vivo NETs was significantly higher in incident HD patients compared to HV, and these markers were strongly associated with ICAM-1. Specifically, nucleosome and ICAM-1 levels were independent predictors of a composite endpoint, all-cause mortality, or vascular access failure. In vitro, HD-derived uremic serum significantly increased NET formation both in dHL-60 and isolated neutrophils compared to control serum, and these NETs decreased EC viability and induced their apoptosis. In addition, the level of ICAM-1, E-selectin and von Willebrand factor in HUVEC supernatant was significantly increased by uremic serum-induced NETs compared to control serum-induced NETs. Dysregulated neutrophil activities in the uremic milieu may play a key role in vascular inflammatory responses. The high mortality and CVD rates in ESRD may be explained in part by excessive NET formation leading to EC damage and dysfunction.

Humoral and cellular response to SARS-CoV-2 BNT162b2 mRNA vaccine in hemodialysis patients.

BACKGROUND: Hemodialysis (HD) patients have an increased risk of acquiring infections due to many health care contacts and may, in addition, have a suboptimal response to vaccination and a high mortality from Covid-19 infection. METHODS: In 50 HD patients (mean age 69.4 years, 62% men) administration of SARS-CoV-2BNT162b2 mRNA vaccine began in Dec 2020 and the immune response was evaluated 7-15 weeks after the last dose. Levels of Covid-19 (SARS-CoV-2) IgG antibody against the nucleocapsid antigen (anti-N) and the Spike antigen (anti-S) and T-cell reactivity testing against the Spike protein using ELISPOT technology were evaluated. RESULTS: Out of 50 patients, anti-S IgG antibodies indicating a vaccine effect or previous Covid-19 infection, were detected in 37 (74%), 5 (10%) had a borderline response and 8 (16%) were negative after two doses of vaccine. T-cell responses were detected in 29 (58%). Of the 37 patients with anti-S antibodies, 25 (68%) had a measurable T-cell response. 2 (40%) out of 5 patients with borderline anti-S and 2 (25%) without anti-S had a concomitant T-cell response. Twenty-seven (54%) had both an antibody and T-cell response. IgG antibodies to anti-N indicating a previous Covid-19 disease were detected in 7 (14%) patients. CONCLUSIONS: Most HD patients develop a B- and/or T-cell response after vaccination against Covid-19 but approx. 20% had a limited immunological response. T-cell reactivity against Covid-19 was only present in a few of the anti-S antibody negative patients.

Comparison of the antiremodeling effects of losartan and mirabegron in a rat model of uremic cardiomyopathy.

Uremic cardiomyopathy is characterized by diastolic dysfunction (DD), left ventricular hypertrophy (LVH), and fibrosis. Angiotensin-II plays a major role in the development of uremic cardiomyopathy via nitro-oxidative and inflammatory mechanisms. In heart failure, the beta-3 adrenergic receptor (ß3-AR) is up-regulated and coupled to endothelial nitric oxide synthase (eNOS)-mediated pathways, exerting antiremodeling effects. We aimed to compare the antiremodeling effects of the angiotensin-II receptor blocker losartan and the ß3-AR agonist mirabegron in uremic cardiomyopathy. Chronic kidney disease (CKD) was induced by 5/6th nephrectomy in male Wistar rats. Five weeks later, rats were randomized into four groups: (1) sham-operated, (2) CKD, (3) losartan-treated (10 mg/kg/day) CKD, and (4) mirabegron-treated (10 mg/kg/day) CKD groups. At week 13, echocardiographic, histologic, laboratory, qRT-PCR, and Western blot measurements proved the development of uremic cardiomyopathy with DD, LVH, fibrosis, inflammation, and reduced eNOS levels, which were significantly ameliorated by losartan. However, mirabegron showed a tendency to decrease DD and fibrosis; but eNOS expression remained reduced. In uremic cardiomyopathy, ß3-AR, sarcoplasmic reticulum ATPase (SERCA), and phospholamban levels did not change irrespective of treatments. Mirabegron reduced the angiotensin-II receptor 1 expression in uremic cardiomyopathy that might explain its mild antiremodeling effects despite the unchanged expression of the ß3-AR.

Mechanism of lncRNA-ANRIL/miR-181b in autophagy of cardiomyocytes in mice with uremia by targeting ATG5.

OBJECTIVES: This study is to investigate whether the cardiac microvascular endothelial cells (CMECs) can regulate the autophagy of cardiomyocytes (CMs) by secreting lncRNA-ANRIL/miR-181b exosomes, thus participating in the occurrence of uremic cardiovascular disease (CVD). METHODS: A 5/6 nephrectomy uremia model was established, with the mice injected with ANRIL-shRNA lentivirus vector, miR-181b agomir, and related control reagents, containing the serum creatinine and urea nitrogen measured. The renal tissue sections of mice were stained with Periodic Acid-Schiff (PAS), TUNEL, and Hematoxylin-Eosin (HE) performed on myocardial tissue sections of mice. ANRIL-shRNA, miR-181b mimics, and related control reagents were transfected into CMECs, in which the exosomes were extracted and co-cultured with CMs. The expressions of ANRIL, miR-181b and ATG5 were detected by qRT-PCR, and the expressions of autophagy related proteins by Western blot, as well as the binding of ANRIL and miR-181b by the double luciferase reporter gene experiment. RESULTS: ANRIL down-regulation or miR-181b up-regulation can increase the weight of mice with uremia, as well as the expressions of p62 and miR-181b, and reduce the content of serum creatinine and urea nitrogen, the damage of kidney and myocardial tissues, the number of apoptotic cells in myocardial tissues, as well as the expressions of ANRIL, ATG5, Beclin1, and LC3. CMs can absorb the exosomes of CMECs. Compared with IS+ CMEC-Exo group, the expressions of ANRIL and ATG5 in CMs of IS+ CMEC-Exo + sh lncRNA ANRIL and IS+CMEC-Exo+miR-181b mimics groups was down-regulated, as well as the expressions of ATG5, Beclin1, and LC3, while miR-181b expression was up-regulated as well as P62 expression. CONCLUSIONS: CMECs can regulate autophagy of CMs by releasing exosomes containing ANRIL and miR-181b.

Globular adiponectin inhibits osteoblastic differentiation of vascular smooth muscle cells through the PI3K/AKT and Wnt/ß-catenin pathway.

Lipid metabolism is closely related to the improvement of vascular calcification (VC) in chronic kidney disease (CKD). Globular adiponectin (gAd) has been reported to be involved in the development of VC in CKD, but the detailed regulatory role remains unclear. The present study is aimed to investigate the biological function and the underlying regulation mechanism of gAd in the process of VC during CKD. Vascular smooth muscle cells (VSMCs) calcification was determined by Alizarin Red S staining. Protein signaling related with VC was tested by western blotting. The expression and intracellular localization of runt-related transcription factor 2 (Runx2) was detected by immunofluorescence and uraemic rat with VC was established by a two-step nephrectomy. Combined with the results of Alizarin Red S staining, we discovered that ß-glycerophosphate (ß-Gp)-induced the osteoblastic differentiation of VSMCs was significantly reversed by gAd treatment. Along with the VSMCs calcification and the increase of Runx2 in ß-Gp-exposed VSMCs, the activities of protein kinase B (AKT) and Wnt/ß-catenin pathway were enhanced, but that were counteracted by the exposure of gAd in rat and human VSMCs. After administration with agonists of the Wnt (SKL2001) and AKT (SC79), there appeared more osteoblastic differentiation and higher expression of Runx2 in gAd-treated VSMCs, but showing lower impact in the presence of SC79 than that in the presence of SKL2001. In the in vivo experiments, intravenous injection of gAd also significantly inhibited VC and Runx2 level in uraemic rat in a dose-dependent manner, possibly through regulating Wnt/ß-catenin pathway. This study demonstrates that gAd ameliorates osteoblastic differentiation of VSMCs possibly by blocking PI3K/AKT and Wnt/ß-catenin signaling transduction. The findings provide an important foundation for gAd in treating VC in kidney diseases.

Early inflammatory changes and CC chemokine ligand-8 upregulation in the heart contribute to uremic cardiomyopathy.

Uremic cardiomyopathy is a common complication in chronic kidney disease (CKD) patients, accounting for a high mortality rate. Several mechanisms have been proposed to link CKD and cardiac alterations; however, the early cardiac modifications that occur in CKD that may trigger cardiac remodeling and dysfunction remain largely unexplored. Here, in a mouse model of CKD induced by 5/6 nephrectomy, we first analyzed the early transcriptional and inflammatory changes that occur in the heart. Five days after 5/6 nephrectomy, RNA-sequencing showed the upregulation of 54 genes in the cardiac tissue of CKD mice and the enrichment of biological processes related to immune system processes. Increased cardiac infiltration of T-CD4+ lymphocytes, myeloid cells, and macrophages during early CKD was observed. Next, since CC chemokine ligand-8 (CCL8) was one of the most upregulated genes in the heart of mice with early CKD, we investigated the effect of acute and transient CCL8 inhibition on uremic cardiomyopathy severity. An increase in CCL8 protein levels was confirmed in the heart of early CKD mice. CCL8 inhibition attenuated the early infiltration of T-CD4+ lymphocytes and macrophages to the cardiac tissue, leading to a protection against chronic cardiac fibrotic remodeling, inflammation and cardiac dysfunction induced by CKD. Altogether, our data show the occurrence of transcriptional and inflammatory changes in the heart during the early phases of CKD and identify CCL8 as a key contributor to the early cardiac inflammatory state that triggers further cardiac remodeling and dysfunction in uremic cardiomyopathy.

Uremia and Inadequate Oxygen Supply Induce Eryptosis and Intracellular Hypoxia in Red Blood Cells.

BACKGROUND/AIMS: Chronic kidney disease is frequently accompanied by anemia, hypoxemia, and hypoxia. It has become clear that the impaired erythropoietin production and altered iron homeostasis are not the sole causes of renal anemia. Eryptosis is a process of red blood cells (RBC) death, like apoptosis of nucleated cells, characterized by Ca2+ influx and phosphatidylserine (PS) exposure to the outer RBC membrane leaflet. Eryptosis can be induced by uremic toxins and occurs before senescence, thus shortening RBC lifespan and aggravating renal anemia. We aimed to assess eryptosis and intracellular oxygen levels of RBC from hemodialysis patients (HD-RBC) and their response to hypoxia, uremia, and uremic toxins uptake inhibition. METHODS: Using flow cytometry, RBC from healthy individuals (CON-RBC) and HD-RBC were subjected to PS (Annexin-V), intracellular Ca2+ (Fluo-3/AM) and intracellular oxygen (Hypoxia Green) measurements, at baseline and after incubation with uremic serum and/or hypoxia (5% O2), with or without ketoprofen. Baseline levels of uremic toxins were quantified in serum and cytosol by high performance liquid chromatography. RESULTS: Here, we show that HD-RBC have less intracellular oxygen and that it is further decreased post-HD. Also, incubation in 5% O2 and uremia triggered eryptosis in vitro by exposing PS. Hypoxia itself increased the PS exposure in HD-RBC and CON-RBC, and the addition of uremic serum aggravated it. Furthermore, inhibition of the organic anion transporter 2 with ketoprofen reverted eryptosis and restored the levels of intracellular oxygen. Cytosolic levels of the uremic toxins pCS and IAA were decreased after dialysis. CONCLUSION: These findings suggest the participation of uremic toxins and hypoxia in the process of eryptosis and intracellular oxygenation.

Uremic Toxins and Their Relation with Oxidative Stress Induced in Patients with CKD.

The presence of toxins is believed to be a major factor in the development of uremia in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Uremic toxins have been divided into 3 groups: small substances dissolved in water, medium molecules: peptides and low molecular weight proteins, and protein-bound toxins. One of the earliest known toxins is urea, the concentration of which was considered negligible in CKD patients. However, subsequent studies have shown that it can lead to increased production of reactive oxygen species (ROS), and induce insulin resistance in vitro and in vivo, as well as cause carbamylation of proteins, peptides, and amino acids. Other uremic toxins and their participation in the damage caused by oxidative stress to biological material are also presented. Macromolecules and molecules modified as a result of carbamylation, oxidative stress, and their adducts with uremic toxins, may lead to cardiovascular diseases, and increased risk of mortality in patients with CKD.

Hyperoxalemia Leads to Oxidative Stress in Endothelial Cells and Mice with Chronic Kidney Disease.

INTRODUCTION: Cardiovascular disease is the most common cause of morbidity and mortality in patients with ESRD. In addition to phosphate overload, oxalate, a common uremic toxin, is also involved in vascular calcification in patients with ESRD. The present study investigated the role and mechanism of hyperoxalemia in vascular calcification in mice with uremia. METHODS: A uremic atherosclerosis (UA) model was established by left renal excision and right renal electrocoagulation in apoE-/- mice to investigate the relationship between oxalate loading and vascular calcification. After 12 weeks, serum and vascular levels of oxalate, vascular calcification, inflammatory factors (TNF-α and IL-6), oxidative stress markers (malondialdehyde [MDA], and advanced oxidation protein products [AOPP]) were assessed in UA mice. The oral oxalate-degrading microbe Oxalobacter formigenes (O. formigenes) was used to evaluate the effect of a reduction in oxalate levels on vascular calcification. The mechanism underlying the effect of oxalate loading on vascular calcification was assessed in cultured human aortic endothelial cells (HAECs) and human aortic smooth muscle cells (HASMCs). RESULTS: Serum oxalate levels were significantly increased in UA mice. Compared to the control mice, UA mice developed more areas of aortic calcification and showed significant increases in aortic oxalate levels and serum levels of oxidative stress markers and inflammatory factors. The correlation analysis showed that serum oxalate levels were positively correlated with the vascular oxalate levels and serum MDA, AOPP, and TNF-α levels, and negatively correlated with superoxide dismutase activity. The O. formigenes intervention decreased serum and vascular oxalate levels, while did not improve vascular calcification significantly. In addition, systemic inflammation and oxidative stress were also improved in the O. formigenes group. In vitro, high concentrations of oxalate dose-dependently increased oxidative stress and inflammatory factor expression in HAECs, but not in HASMCs. CONCLUSIONS: Our results indicated that hyperoxalemia led to the systemic inflammation and the activation of oxidative stress. The reduction in oxalate levels by O. formigenes might be a promising treatment for the prevention of oxalate deposition in calcified areas of patients with ESRD.

Uremic endothelial-derived extracellular vesicles: Mechanisms of formation and their role in cell adhesion, cell migration, inflammation, and oxidative stress.

p-Cresyl sulfate (PCS), indoxyl sulfate (IS), and inorganic phosphate (Pi) are uremic toxins found in chronic kidney disease (CKD) that are closely related to endothelial extracellular vesicles (EVs) formation. The present study aimed to understand the role of EVs and their role in cell adhesion and migration, inflammation, and oxidative stress. Human endothelial cells were treated with PCS, IS, and Pi in pre-established uremic and kinetic recommendations. EVs were characterized using scanning electron microscopy, flow cytometry, and NanoSight assays. The concentrations of EVs were established using Alamar Blue and MTT assays. Cell adhesion to extracellular matrix proteins was analyzed using an adhesion assay. Inflammation and oxidative stress were assessed by vascular cell adhesion molecule-1 expression/monocyte migration and reactive oxygen species production, respectively. The capacity of EVs to stimulate endothelial cell migration was evaluated using a wound-healing assay. Our data showed that endothelial cells stimulated with uremic toxins can induce the formation of EVs of different sizes, quantities, and concentrations, depending on the uremic toxin used. Cell adhesion was significantly (P < 0.01) stimulated in cells exposed to PCS-induced extracellular vesicles (PCSEVs) and inorganic phosphate-induced extracellular vesicles (PiEVs). Cell migration was significantly (P < 0.05) stimulated by PCSEVs. VCAM-1 expression was evident in cells treated with PCSEVs and IS-induced extracellular vesicles (ISEVs). EVs are not able to stimulate monocyte migration or oxidative stress. In conclusion, EVs may be a biomarker of endothelial injury and the inflammatory process, playing an important role in cell-to-cell communication and pathophysiological processes, although more studies are needed to better understand the mechanisms of EVs in uremia.

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.

Concerted outcome of metformin and low dose of radiation in modulation of cisplatin induced uremic encephalopathy via renal and neural preservation.

AIM: The therapeutic expediency of cisplatin was limited due to its nephrotoxic side effects, so this study planned to assess the nephrotic and neuroprotective impact of metformin (MET) and low-dose radiation (LDR) in cisplatin-prompted kidney injury and uremic encephalopathy (UE). METHODS: The effect of the 10-day MET treatment (200 mg/kg, orally) and/or fractionated LDR (0.25 Gy, of the total dose of 0.5 Gy, 1st and 7th day, respectively) on (5 mg/kg, intraperitoneally) cisplatin as a single dose was administered at the 5th day. Serum urea, creatinine and renal kidney injury molecule-1 were measured for the assessment of kidney function. Furthermore, the antioxidant potential in the renal and brain tissues was evaluated through, malondialdehyde and reduced glutathione estimation. Moreover, renal apoptotic markers: AMP-activated protein kinase, lipocalin, B-cell lymphoma 2 associated X protein, B-cell lymphoma 2, P53 and beclin 1 were estimated. UE was evaluated through the determination of serum inflammatory markers: nuclear factor kappa B, tumor-necrosis factor-α and interleukin 1 beta likewise, the cognitive deficits were assessed via forced swimming test, gamma-aminobutyric acid, n-methyl-d-aspartate and neuronal nitric oxide synthases besides AMP-activated protein kinase, light chain 3 and caspase3 levels in rats' cerebella. KEY FINDINGS: The obtained results revealed a noticeable improvement in the previously mentioned biochemical factors and behavioral tasks that was reinforced by histopathological examination when using the present remedy. SIGNIFICANCE: metformin and low doses of radiation afforded renoprotection and neuroprotection against cisplatin-induced acute uremic encephalopathy.

Endothelial glycocalyx damage in kidney disease correlates with uraemic toxins and endothelial dysfunction.

BACKGROUND: Damage to the endothelial glycocalyx is an early indicator of vascular damage and a potential marker of endothelial dysfunction. This study aimed to assess the relationship between markers of glycocalyx damage, endothelial dysfunction, and uraemic toxins in patients with chronic kidney disease. METHODS: Healthy controls, CKD patients, dialysis patients, and kidney transplant recipients had biochemical markers of glycocalyx damage (syndecan-1 and hyaluronan), endothelial dysfunction (von Willebrand factor; vWF and vascular cell adhesion molecule; VCAM-1), and uraemic toxins (indoxyl sulphate and p-cresyl sulphate) measured. In addition, Sidestream Darkfield imaging was performed using the novel GlycoCheck™ device to measure glycocalyx width by the perfused boundary region (PBR) in the sublingual microcirculation. RESULTS: Serum markers of glycocalyx damage were highest in the dialysis group (n = 33), followed by CKD patients (n = 32) and kidney transplant recipients (n = 30) compared to controls (n = 30): hyaluronan: 137 (16-1414), 79 (11-257), 57 (14-218) and 23 (8-116) ng/mL, respectively, p < 0.0001; syndecan-1: 81 (40-529), 46 (21-134), 39 (23-72), and 30 (12-138) ng/mL, respectively, p < 0.0001. Markers of endothelial dysfunction followed a similar pattern. No difference in the width of the PBR was detected between these groups (2.01 ± 0.35, 2.07 ± 0.27, 2.06 ± 0.28, and 2.05 ± 0.3 µm, respectively, p = 0.89). Glycocalyx damage correlated with markers of endothelial dysfunction (log-hyaluronan and log-VCAM-1: r = 0.64, p < 0.001) and levels of uraemic toxins (log-hyaluronan and log-indoxyl sulphate: r = 0.48, p < 0.001). CONCLUSIONS: Levels of biochemical markers of glycocalyx and endothelial cell damage are highest in patients receiving dialysis. Glycocalyx and endothelial damage markers correlated with each other, and with uraemic toxins. Although we could not demonstrate a change in PBR, the biochemical markers suggest that glycocalyx damage is most marked in patients with higher levels of uraemic toxins.

The Crosstalk between Calcium Ions and Aldosterone Contributes to Inflammation, Apoptosis, and Calcification of VSMC via the AIF-1/NF-κB Pathway in Uremia.

Vascular calcification is a major complication of maintenance hemodialysis patients. Studies have confirmed that calcification mainly occurs in the vascular smooth muscle cells (VSMC) of the vascular media. However, the exact pathogenesis of VSMC calcification is still unknown. This study shows that the crosstalk between calcium and aldosterone via the allograft inflammatory factor 1 (AIF-1) pathway contributes to calcium homeostasis and VSMC calcification, which is a novel mechanism of vascular calcification in uremia. In vivo results showed that the level of aldosterone and inflammatory factors increased in calcified arteries, whereas no significant changes were observed in peripheral blood. However, the expression of inflammatory factors markedly increased in the peripheral blood of uremic rats without aortic calcification and gradually returned to normal levels with aggravation of aortic calcification. In vitro results showed that there was an interaction between calcium ions and aldosterone in macrophages or VSMC. Calcium induced aldosterone synthesis, and in turn, aldosterone also triggered intracellular calcium content upregulation in macrophages or VSMC. Furthermore, activated macrophages induced inflammation, apoptosis, and calcification of VSMC. Activated VSMC also imparted a similar effect on untreated VSMC. Finally, AIF-1 enhanced aldosterone- or calcium-induced VSMC calcification, and NF-κB inhibitors inhibited the effect of AIF-1 on VSMC. These in vivo and in vitro results suggest that the crosstalk between calcium ions and aldosterone plays an important role in VSMC calcification in uremia via the AIF-1/NF-κB pathway. Local calcified VSMC induced the same pathological process in surrounding VSMC, thereby contributing to calcium homeostasis and accelerating vascular calcification.

Uremic Toxins Affecting Cardiovascular Calcification: A Systematic Review.

Cardiovascular calcification is highly prevalent and associated with increased morbidity in chronic kidney disease (CKD). This review examines the impact of uremic toxins, which accumulate in CKD due to a failing kidney function, on cardiovascular calcification. A systematic literature search identified 41 uremic toxins that have been studied in relation to cardiovascular calcification. For 29 substances, a potentially causal role in cardiovascular calcification was addressed in in vitro or animal studies. A calcification-inducing effect was revealed for 16 substances, whereas for three uremic toxins, namely the guanidino compounds asymmetric and symmetric dimethylarginine, as well as guanidinosuccinic acid, a calcification inhibitory effect was identified in vitro. At a mechanistic level, effects of uremic toxins on calcification could be linked to the induction of inflammation or oxidative stress, smooth muscle cell osteogenic transdifferentiation and/or apoptosis, or alkaline phosphatase activity. For all middle molecular weight and protein-bound uremic toxins that were found to affect cardiovascular calcification, an increasing effect on calcification was revealed, supporting the need to focus on an increased removal efficiency of these uremic toxin classes in dialysis. In conclusion, of all uremic toxins studied with respect to calcification regulatory effects to date, more uremic toxins promote rather than reduce cardiovascular calcification processes. Additionally, it highlights that only a relatively small part of uremic toxins has been screened for effects on calcification, supporting further investigation of uremic toxins, as well as of associated post-translational modifications, on cardiovascular calcification processes.