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1.
Aging (Albany NY) ; 16(5): 4236-4249, 2024 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-38385990

RESUMEN

BACKGROUND AND HYPOTHESIS: Pruritus is a common and distressing symptom that affects patients with chronic kidney disease. The concentration of protein bounded uremic toxin was associated with the uremic pruritus. The aim is to assess the efficacy of AST-120 for uremic pruritus in hemodialysis patients. MATERIALS AND METHODS: The participants were enrolled and then divided into the AST-120 treatment group and control group with a ratio of 2:1. All participants underwent pre-observation screenings two weeks before the study with three visits. In the treatment phase (week 1 to week 4), the treatment group added 6g/day of AST-120 along with routine anti-pruritic treatment. Visual analog scale (VAS) and biochemical parameters were measured. RESULTS: The VAS score began to be lower in the AST-120 treatment group after the 5th visiting (p < 0.05). The reduction in indoxyl sulfate (IS) at 5th week along with TNF-alpha. The reduction ratio of indoxyl sulfate correlated with reduction of parathyroid hormone. CONCLUSION: This study has demonstrated that the four-week treatment of AST-120 decreased the severity of uremic pruritus in patients with ESRD. The concentration of IS and TNF-alpha decreased in the AST-120 treatment group. The reduction of iPTH correlated with the reduction of IS in the AST-120 treatment.


Asunto(s)
Carbono , Indicán , Óxidos , Uremia , Humanos , Uremia/complicaciones , Uremia/metabolismo , Citocinas , Factor de Necrosis Tumoral alfa , Diálisis Renal/efectos adversos , Prurito/tratamiento farmacológico , Prurito/etiología
3.
Ann Biomed Eng ; 52(3): 526-541, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37993752

RESUMEN

Inadequate clearance of protein-bound uremic toxins (PBUTs) during dialysis is associated with morbidities in chronic kidney disease patients. The development of high-permeance membranes made from materials such as graphene raises the question whether they could enable the design of dialyzers with improved PBUT clearance. Here, we develop device-level and multi-compartment (body) system-level models that account for PBUT-albumin binding (specifically indoxyl sulfate and p-cresyl sulfate) and diffusive and convective transport of toxins to investigate how the overall membrane permeance (or area) and system parameters including flow rates and ultrafiltration affect PBUT clearance in hemodialysis. Our simulation results indicate that, in contrast to urea clearance, PBUT clearance in current dialyzers is mass-transfer limited: Assuming that the membrane resistance is dominant, raising PBUT permeance from 3 × 10-6 to 10-5 m s-1 (or equivalently, 3.3 × increase in membrane area from ~ 2 to ~ 6 m2) increases PBUT removal by 48% (from 22 to 33%, i.e., ~ 0.15 to ~ 0.22 g per session), whereas increasing dialysate flow rates or adding adsorptive species have no substantial impact on PBUT removal unless permeance is above ~ 10-5 m s-1. Our results guide the future development of membranes, dialyzers, and operational parameters that could enhance PBUT clearance and improve patient outcomes.


Asunto(s)
Toxinas Biológicas , Uremia , Humanos , Tóxinas Urémicas , Uremia/terapia , Uremia/metabolismo , Unión Proteica , Diálisis Renal/métodos , Toxinas Biológicas/metabolismo
4.
Ther Apher Dial ; 27(6): 1023-1027, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37596835

RESUMEN

INTRODUCTION: Indoxyl sulfate (IS) is a protein-bound uremic toxin that causes uremic sarcopenia. IS has poor dialysis clearance; however, the addition of a binding competitor improves its removal efficiency. METHODS: Dialysis experiments were performed using N-acetyl-l-tryptophan (L-NAT) instead of l-tryptophan (Trp) using pooled sera obtained from dialysis patients. The molecular structures of L-NAT and Trp were similar to that of IS. Therefore, we examined whether Trp and L-NAT were involved in muscle atrophy in the same manner as IS by performing culture experiments using a human myotube cell line. RESULTS: The removal efficiency of L-NAT was the same as that of Trp. However, L-NAT concentrations in the pooled sera increased at the end of the experiment. Trp (1 mM) decreased the area of human myocytes, similar to IS, whereas L-NAT did not. CONCLUSION: L-NAT is a binding competitor with the ability to remove protein-bound IS while preventing sarcopenia.


Asunto(s)
Sarcopenia , Uremia , Humanos , Sarcopenia/metabolismo , Uremia/metabolismo , Indicán , Triptófano , Tóxinas Urémicas
5.
Thromb Haemost ; 123(12): 1116-1128, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37364609

RESUMEN

BACKGROUND: Although thrombosis events are the leading complication of uremia, their mechanism is largely unknown. The interaction between endothelial cells (ECs) and red blood cells (RBCs) in uremic solutes and its prothrombotic role need to be investigated. METHODS AND RESULTS: Here, we established an in vitro co-incubation model of uremic RBC and EC as well as a uremic rat model induced by adenine. Using flow cytometry, confocal microscopy, and electron microscopy, we found increased erythrophagocytosis by EC accompanied by increased reactive oxygen species, lipid peroxidation, and impairment of mitochondria, indicating that ECs undergo ferroptosis. Further investigations showed increased proteins' expression of heme oxygenase-1 and ferritin and labile iron pool accumulation in EC, which could be suppressed by deferoxamine (DFO). The ferroptosis-negative regulators glutathione peroxidase 4 and SLC7A11 were decreased in our erythrophagocytosis model and could be enhanced by ferrostatin-1 or DFO. In vivo, we observed that vascular EC phagocytosed RBC and underwent ferroptosis in the kidney of the uremic rat, which could be inhibited by blocking the phagocytic pathway or inhibiting ferroptosis. Next, we found that the high tendency of thrombus formation was accompanied by erythrophagocytosis-induced ferroptosis in vitro and in vivo. Importantly, we further revealed that upregulated TMEM16F expression mediated phosphatidylserine externalization on ferroptotic EC, which contributed to a uremia-associated hypercoagulable state. CONCLUSION: Our results indicate that erythrophagocytosis-triggered ferroptosis followed by phosphatidylserine exposure of EC may play a key role in uremic thrombotic complications, which may be a promising target to prevent thrombogenesis of uremia.


Asunto(s)
Ferroptosis , Trombosis , Uremia , Ratas , Animales , Células Endoteliales/metabolismo , Fosfatidilserinas/metabolismo , Eritrocitos , Uremia/metabolismo
6.
Eur J Pharm Sci ; 187: 106462, 2023 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-37169097

RESUMEN

Chronic kidney disease is multifactorial and estimated to affect more than 840 million people worldwide constituting a major global health crisis. The number of patients will continue to rise mostly because of the aging population and the increased prevalence of comorbidities such as diabetes and hypertension. Patients with advanced stages display a loss of kidney function leading to an accumulation of, a.o. protein-bound uremic toxins that are poorly eliminated by renal replacement therapies. This systemic retention of toxic metabolites, known as the uremic syndrome, affects other organs. Indeed, neurological complications such as cognitive impairment, uremic encephalopathy, and anxiety have been reported in chronic kidney disease patients. Several factors are involved, including hemodynamic disorders and blood-brain barrier (BBB) impairment. The BBB guarantees the exchange of solutes between the blood and the brain through a complex cellular organization and a diverse range of transport proteins. We hypothesize that the increased exposure of the brain to protein-bound uremic toxins is involved in BBB disruption and induces a perturbation in the activity of endothelial membrane transporters. This phenomenon could play a part in the evolution of neurological disorders driven by this kidney-brain crosstalk impairment. In this review, we present chronic kidney disease-induced neurological complications by focusing on the pathological relationship between the BBB and protein-bound uremic toxins. The importance of mechanistically delineating the impact of protein-bound uremic toxins on BBB integrity and membrane drug transporter expression and function in brain endothelial capillary cells is highlighted. Additionally, we put forward current knowledge gaps in the literature.


Asunto(s)
Enfermedades del Sistema Nervioso , Insuficiencia Renal Crónica , Toxinas Biológicas , Uremia , Humanos , Anciano , Barrera Hematoencefálica/metabolismo , Tóxinas Urémicas , Uremia/metabolismo , Uremia/terapia , Toxinas Biológicas/metabolismo , Toxinas Biológicas/toxicidad , Insuficiencia Renal Crónica/complicaciones , Insuficiencia Renal Crónica/metabolismo , Insuficiencia Renal Crónica/terapia
7.
Int J Mol Sci ; 24(8)2023 Apr 18.
Artículo en Inglés | MEDLINE | ID: mdl-37108613

RESUMEN

Chronic kidney disease is the gradual progression of kidney dysfunction and involves numerous co-morbidities, one of the leading causes of mortality. One of the primary complications of kidney dysfunction is the accumulation of toxins in the bloodstream, particularly protein-bound uremic toxins (PBUTs), which have a high affinity for plasma proteins. The buildup of PBUTs in the blood reduces the effectiveness of conventional treatments, such as hemodialysis. Moreover, PBUTs can bind to blood plasma proteins, such as human serum albumin, alter their conformational structure, block binding sites for other valuable endogenous or exogenous substances, and exacerbate the co-existing medical conditions associated with kidney disease. The inadequacy of hemodialysis in clearing PBUTs underscores the significance of researching the binding mechanisms of these toxins with blood proteins, with a critical analysis of the methods used to obtain this information. Here, we gathered the available data on the binding of indoxyl sulfate, p-cresyl sulfate, indole 3-acetic acid, hippuric acid, 3-carboxyl-4-methyl-5-propyl-2-furan propanoic acid, and phenylacetic acid to human serum albumin and reviewed the common techniques used to investigate the thermodynamics and structure of the PBUT-albumin interaction. These findings can be critical in investigating molecules that can displace toxins on HSA and improve their clearance by standard dialysis or designing adsorbents with greater affinity for PBUTs than HSA.


Asunto(s)
Toxinas Biológicas , Uremia , Humanos , Albúmina Sérica Humana/metabolismo , Tóxinas Urémicas , Diálisis Renal/efectos adversos , Uremia/metabolismo , Unión Proteica , Proteínas Sanguíneas/metabolismo , Toxinas Biológicas/metabolismo
8.
Bioanalysis ; 14(24): 1563-1581, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36846891

RESUMEN

Aim: Protein-bound uremic toxins (PBUTs) may displace drugs from the plasma proteins and render them more liable to clearance. This study aims to investigate the possible interplay between PBUTs and directly acting antivirals (DAAs). Methods: PBUT plasma protein binding was compared to those of paritaprevir (PRT), ombitasivir (OMB) and ritonavir (RTV) in silico to assess the possible competitive displacement. The three drugs were LC-MS/MS determined in seven patients across dialysis and non-dialysis days and results were compared. Results & conclusion: Results showed that the PBUT exhibited a lower binding than DAA reducing the liability of their competitive displacement. This was echoed by an unaltered plasma concentration across dialysis days. Results may indicate that PBUT accumulation may have limited effect on disposition of DAA.


Asunto(s)
Toxinas Biológicas , Uremia , Humanos , Antivirales , Cromatografía Liquida , Uremia/metabolismo , Espectrometría de Masas en Tándem , Diálisis Renal/métodos , Proteínas Sanguíneas/metabolismo , Toxinas Biológicas/metabolismo
9.
Toxins (Basel) ; 15(2)2023 01 28.
Artículo en Inglés | MEDLINE | ID: mdl-36828424

RESUMEN

End-stage renal disease (ESRD) patients rely on renal replacement therapies to survive. Hemodialysis (HD), the most widely applied treatment, is responsible for the removal of excess fluid and uremic toxins (UTs) from blood, particularly those with low molecular weight (MW < 500 Da). The development of high-flux membranes and more efficient treatment modes, such as hemodiafiltration, have resulted in improved removal rates of UTs in the middle molecular weight range. However, the concentrations of protein-bound uremic toxins (PBUTs) remain essentially untouched. Due to the high binding affinity to large proteins, such as albumin, PBUTs form large complexes (MW > 66 kDa) which are not removed during HD and their accumulation has been strongly associated with the increased morbidity and mortality of patients with ESRD. In this review, we describe adsorption- and displacement-based approaches currently being studied to enhance the removal of PBUTs. The development of mixed matrix membranes (MMMs) with selective adsorption properties, infusion of compounds capable of displacing UTs from their binding site on albumin, and competitive binding membranes show promising results, but the road to clinical application is still long, and further investigation is required.


Asunto(s)
Fallo Renal Crónico , Toxinas Biológicas , Uremia , Humanos , Tóxinas Urémicas , Uremia/metabolismo , Adsorción , Unión Proteica , Toxinas Biológicas/metabolismo , Diálisis Renal/métodos , Albúminas/metabolismo
10.
Toxins (Basel) ; 15(2)2023 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-36828430

RESUMEN

Patients with chronic kidney disease (CKD) have a higher cardiovascular risk compared to the average population, and this is partially due to the plasma accumulation of solutes known as uremic toxins. The binding of some solutes to plasma proteins complicates their removal via conventional therapies, e.g., hemodialysis. Protein-bound uremic toxins originate either from endogenous production, diet, microbial metabolism, or the environment. Although the impact of diet on uremic toxicity in CKD is difficult to quantify, nutrient intake plays an important role. Indeed, most uremic toxins are gut-derived compounds. They include Maillard reaction products, hippurates, indoles, phenols, and polyamines, among others. In this review, we summarize the findings concerning foods and dietary components as sources of uremic toxins or their precursors. We then discuss their endogenous metabolism via human enzyme reactions or gut microbial fermentation. Lastly, we present potential dietary strategies found to be efficacious or promising in lowering uremic toxins plasma levels. Aligned with current nutritional guidelines for CKD, a low-protein diet with increased fiber consumption and limited processed foods seems to be an effective treatment against uremic toxins accumulation.


Asunto(s)
Insuficiencia Renal Crónica , Toxinas Biológicas , Uremia , Humanos , Tóxinas Urémicas , Toxinas Biológicas/toxicidad , Insuficiencia Renal Crónica/metabolismo , Alimentos , Dieta con Restricción de Proteínas , Uremia/metabolismo
11.
J Chromatogr B Analyt Technol Biomed Life Sci ; 1215: 123578, 2023 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-36610265

RESUMEN

Protein-bound uremic retention solutes, such as indole-3-acetic acid, indoxyl sulfate, p-cresol and p-cresol sulfate, are associated with the development of several pathologies, namely renal, cardiovascular, and bone toxicities, due to their potential accumulation in the human body, thus requiring analytical methods for monitoring and evaluation. The present review addresses conventional and advanced sample treatment procedures for sample handling and the chromatographic analytical methods developed for quantification of these compounds in different biological fluids, with particular focus on plasma, serum, and urine. The sample preparation and chromatographic methods coupled to different detection systems are critically discussed, focusing on the different steps involved for sample treatment, namely elimination of interfering compounds present in the sample matrix, and the evaluation of their environmental impact through the AGREEprep tool. There is a clear trend for the application of liquid-chromatography coupled to tandem mass spectrometry, which requires protein precipitation, solid-phase extraction and/or dilution prior to analysis of biological samples. Furthermore, from a sustainability point of view, miniaturized methods resorting to microplate devices are highly recommended.


Asunto(s)
Fallo Renal Crónico , Uremia , Humanos , Uremia/metabolismo , Tóxinas Urémicas , Cresoles , Cromatografía Liquida , Manejo de Especímenes
12.
J Mater Chem B ; 11(1): 55-60, 2022 12 22.
Artículo en Inglés | MEDLINE | ID: mdl-36504125

RESUMEN

Hemodialysis fails to remove protein-bound uremic toxins that are attributed with high cardiovascular risk. Application of adsorption materials is a viable strategy, but suitable biocompatible adsorbents are still not available. Here, we demonstrate that adsorbents based on the bottom-up assembly of the intrinsically biocompatible protein cage ferritin are applicable for toxin adsorption. Due to the size-exclusion effect of its pores, only small molecules such as uremic toxins can enter the protein cage. Protein redesign techniques that target selectively the inner surface were used to introduce anchor sites for chemical modification. Porous crystalline adsorbents were fabricated by bottom-up assembly of the protein cage. Linkage of up to 96 phenylic or aliphatic molecules per container was verified by ESI-MS. Materials based on unmodified ferritin cages can already adsorb the uremic toxins. The adsorption capacity could be increased by about 50% through functionalization with hydrophobic molecules reaching 458 µg g-1 for indoxyl sulfate. The biohybrid materials show no contamination with endotoxins and do not activate blood platelets. These findings demonstrate the great potential of protein-based adsorbents for the clearance of uremic toxins: modifications enhance toxin adsorption without diminishing the biocompatibility of the final protein-based material.


Asunto(s)
Toxinas Biológicas , Uremia , Humanos , Tóxinas Urémicas , Uremia/metabolismo , Adsorción , Diálisis Renal/métodos , Ferritinas
13.
Ren Fail ; 44(1): 1819-1832, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36299239

RESUMEN

BACKGROUND/AIM: Uremic cardiomyopathy (UCM) is a characteristic cardiac pathology that is commonly found in patients with chronic kidney disease. This study dissected the mechanism of SPI1 in myocardial fibrosis and inflammation induced by UCM through S100A8/A9. METHODS: An UCM rat model was established, followed by qRT-PCR and western blot analyses of SPI1 and S100A8/A9 expression in myocardial tissues. After alterations of SPI1 and S100A8/A9 expression in UCM rats, the blood specimens were harvested from the cardiac apex of rats. The levels of creatine phosphokinase-MB (CK-MB), blood creatinine, blood urea nitrogen (BUN), and inflammatory cytokines (interleukin [IL]-6, IL-1ß, and tumor necrosis factor-α [TNF-α]) were examined in the collected blood. Collagen fibrosis was assessed by Masson staining. The expression of fibrosis markers [transforming growth factor (TGF)-ß1, α-smooth muscle actin (SMA), Collagen 4a1, and Fibronectin], IL-6, IL-1ß, and TNF-α was measured in myocardial tissues. Chromatin immunoprecipitation and dual-luciferase reporter gene assays were conducted to test the binding relationship between SPI1 and S100A8/A9. RESULTS: S100A8/A9 and SPI1 were highly expressed in the myocardial tissues of UCM rats. Mechanistically, SPI1 bound to the promoter of S100A8/A9 to facilitate S100A8/A9 transcription. S100A8/A9 or SPI1 knockdown reduced myocardial fibrosis and inflammation and the levels of CK-MB, blood creatinine, and BUN, as well as the expression of TGF-ß1, α-SMA, Collagen 4a1, Fibronectin, IL-6, TNF-α, and IL-1ß in UCM rats. CONCLUSION: SPI1 knockdown diminished S100A8/A9 transcription, thus suppressing myocardial fibrosis and inflammation caused by UCM.


Asunto(s)
Calgranulina A , Calgranulina B , Cardiomiopatías , Animales , Ratas , Actinas/metabolismo , Calgranulina A/genética , Calgranulina A/metabolismo , Calgranulina B/genética , Calgranulina B/metabolismo , Cardiomiopatías/genética , Cardiomiopatías/metabolismo , Cardiomiopatías/patología , Cardiomiopatías/prevención & control , Creatina Quinasa , Creatinina , Citocinas/metabolismo , Regulación hacia Abajo , Fibronectinas/metabolismo , Fibrosis/genética , Fibrosis/metabolismo , Islas Genómicas , Inflamación/genética , Inflamación/metabolismo , Interleucina-6/metabolismo , Luciferasas/genética , Luciferasas/metabolismo , Proteína SUMO-1/genética , Proteína SUMO-1/metabolismo , Factor de Crecimiento Transformador beta1/metabolismo , Factores de Crecimiento Transformadores/genética , Factores de Crecimiento Transformadores/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Uremia/complicaciones , Uremia/genética , Uremia/metabolismo
14.
Ter Arkh ; 93(6): 729-735, 2021 Jun 15.
Artículo en Ruso | MEDLINE | ID: mdl-36286841

RESUMEN

Chronic kidney disease (CKD) is characterized by high mortality from cardiovascular diseases, the development of which is facilitated by traditional risk factors (typical for the general population) and by nontraditional ones (specific to patients with CKD) as well. These factors include also uremic toxins, for which a causal relationship has been established with specific pathological processes in patients with CKD, comprising the development of vascular dysfunction and accelerated progression of atherosclerosis. Urea has long been considered not as a uremic toxin, but as a marker of metabolic imbalance or dialysis efficiency (Kt/V) in CKD patients. In recent years, more and more publications have appeared on the study of the toxic effects of urea with the development of toxic-uremic complications and the phenotype of premature aging, common in CKD. It was found that an increase in urea levels in uremic syndrome causes damage to the intestinal epithelial barrier with translocation of bacterial toxins into the bloodstream and the development of systemic inflammation, provokes apoptosis of vascular smooth muscle cells, as well as endothelial dysfunction, which directly contributes to the development of cardiovascular complications. The indirect effects of increased urea levels are associated with carbamylation reactions, when isocyanic acid (a product of urea catabolism) changes the structure and function of proteins in the body. Carbamylation of proteins in CKD patients is associated with the development of renal fibrosis, atherosclerosis and anemia. Thus, urea is now regarded as an important negative agent in the pathogenesis of complications in CKD. Studies on a low-protein diet with using ketoanalogues of essential amino acids to minimize the accumulation of urea and other uremic toxins demonstrate the clinical benefit of such an intervention in slowing the progression of CKD and the development of cardiovascular complications.


Asunto(s)
Aterosclerosis , Toxinas Bacterianas , Insuficiencia Renal Crónica , Uremia , Humanos , Dieta con Restricción de Proteínas/efectos adversos , Carbamilación de Proteína , Urea , Aminoácidos Esenciales , Tóxinas Urémicas , Insuficiencia Renal Crónica/complicaciones , Proteínas/metabolismo , Toxinas Bacterianas/metabolismo , Aterosclerosis/complicaciones , Uremia/complicaciones , Uremia/metabolismo
15.
Curr Nutr Rep ; 11(4): 765-779, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36138326

RESUMEN

PURPOSE OF REVIEW: This narrative review aimed to summarize the current evidence on the connection between dysbiosis and vitamin K deficiency in patients with chronic kidney disease (CKD). The presence of dysbiosis (perturbations in the composition of the microbiota) has been described in several non-communicable diseases, including chronic kidney disease, and it has been hypothesized that dysbiosis may cause vitamin K deficiency. Patients with CKD present both vitamin K deficiency and gut dysbiosis; however, the relationship between gut dysbiosis and vitamin K deficiency remains to be addressed. RECENT FINDINGS: Recently, few studies in animals have demonstrated that a dysbiotic environment is associated with low production of vitamin K by the gut microbiota. Vitamin K plays a vital role in blood coagulation as well as in the cardiovascular and bone systems. It serves as a cofactor for γ-glutamyl carboxylases and thus is essential for the post-translational modification and activation of vitamin K-dependent calcification regulators, such as osteocalcin, matrix Gla protein, Gla-rich protein, and proteins C and S. Additionally, vitamin K executes essential antioxidant and anti-inflammatory functions. Dietary intake is the main source of vitamin K; however, it also can be produced by gut microbiota. This review discusses the effects of uremia on the imbalance in gut microbiota, vitamin K-producing bacteria, and vitamin K deficiency in CKD patients, leading to a better understanding and raising hypothesis for future clinical studies.


Asunto(s)
Insuficiencia Renal Crónica , Uremia , Deficiencia de Vitamina K , Animales , Humanos , Disbiosis , Vitamina K/metabolismo , Insuficiencia Renal Crónica/microbiología , Uremia/metabolismo , Uremia/microbiología , Deficiencia de Vitamina K/complicaciones , Deficiencia de Vitamina K/metabolismo
16.
Cell Biochem Funct ; 40(8): 856-864, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36121199

RESUMEN

Oxidative stress (OS) is essential in uremia-associated comorbidities, including renal anemia. Complications experienced by hemodialysis (HD) patients, such as hypoxemia and uremic toxins accumulation, induce OS and premature death of red blood cells (RBC). We aimed to characterize reactive oxygen species (ROS) production and antioxidant pathways in HD-RBC and RBC from healthy controls (CON-RBC) and evaluate the role of uremia and hypoxia in these pathways. ROS production, xanthine oxidase (XO) and superoxide dismutase (SOD) activities, glutathione (GSH), and heme oxygenase-1 (HO-1) levels were measured using flow cytometry or spectrophotometry in CON-RBC and HD-RBC (pre- and post-HD), at baseline and after 24 h incubation with uremic serum (S-HD) and/or under hypoxic conditions (5% O2 ). Ketoprofen was used to inhibit RBC uremic toxins uptake. HD-RBC showed higher ROS levels and lower XO activity than CON-RBC, particularly post-HD. GSH levels were lower, while SOD activity and HO-1 levels of HD-RBC were higher than control. Hypoxia per se triggered ROS production in CON-RBC and HD-RBC. S-HD, on top of hypoxia, increased ROS levels. Inhibition of uremic toxins uptake attenuated ROS of CON and HD-RBC under hypoxia and uremia. CON-RBC in uremia and hypoxia showed lower GSH levels than cells in normoxia and non-uremic conditions. Redox mechanisms of HD-RBC are altered and prone to oxidation. Uremic toxins and hypoxia play a role in unbalancing these systems. Hypoxia and uremia participate in the pathogenesis of OS in HD-RBC and might induce RBC death and thus compound anemia.


Asunto(s)
Anemia , Uremia , Humanos , Eritrocitos/metabolismo , Uremia/metabolismo , Diálisis Renal , Estrés Oxidativo , Glutatión/metabolismo , Hipoxia/metabolismo , Anemia/metabolismo
17.
J Am Soc Nephrol ; 33(10): 1841-1856, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-36038265

RESUMEN

BACKGROUND: Bleeding diatheses, common among patients with ESKD, can lead to serious complications, particularly during invasive procedures. Chronic urea overload significantly increases cyanate concentrations in patients with ESKD, leading to carbamylation, an irreversible modification of proteins and peptides. METHODS: To investigate carbamylation as a potential mechanistic link between uremia and platelet dysfunction in ESKD, we used liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to quantify total homocitrulline, and biotin-conjugated phenylglyoxal labeling and Western blot to detect carbamylated integrin α IIb ß 3 (a receptor required for platelet aggregation). Flow cytometry was used to study activation of isolated platelets and platelet-rich plasma. In a transient transfection system, we tested activity and fibrinogen binding of different mutated forms of the receptor. We assessed platelet adhesion and aggregation in microplate assays. RESULTS: Carbamylation inhibited platelet activation, adhesion, and aggregation. Patients on hemodialysis exhibited significantly reduced activation of α IIb ß 3 compared with healthy controls. We found significant carbamylation of both subunits of α IIb ß 3 on platelets from patients receiving hemodialysis versus only minor modification in controls. In the transient transfection system, modification of lysine 185 in the ß 3 subunit was associated with loss of receptor activity and fibrinogen binding. Supplementation of free amino acids, which was shown to protect plasma proteins from carbamylation-induced damage in patients on hemodialysis, prevented loss of α IIb ß 3 activity in vitro. CONCLUSIONS: Carbamylation of α IIb ß 3-specifically modification of the K185 residue-might represent a mechanistic link between uremia and dysfunctional primary hemostasis in patients on hemodialysis. The observation that free amino acids prevented the carbamylation-induced loss of α IIb ß 3 activity suggests amino acid administration during dialysis may help to normalize platelet function.


Asunto(s)
Complejo GPIIb-IIIa de Glicoproteína Plaquetaria , Uremia , Humanos , Complejo GPIIb-IIIa de Glicoproteína Plaquetaria/química , Complejo GPIIb-IIIa de Glicoproteína Plaquetaria/genética , Complejo GPIIb-IIIa de Glicoproteína Plaquetaria/metabolismo , Carbamilación de Proteína , Espectrometría de Masas en Tándem , Plaquetas , Uremia/complicaciones , Uremia/metabolismo , Fibrinógeno/química , Fibrinógeno/metabolismo , Aminoácidos
18.
J Mol Med (Berl) ; 100(9): 1321-1330, 2022 09.
Artículo en Inglés | MEDLINE | ID: mdl-35916902

RESUMEN

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.


Asunto(s)
Fallo Renal Crónico , Uremia , Calcificación Vascular , Adenina/uso terapéutico , Envejecimiento , Animales , Modelos Animales de Enfermedad , Inflamación/complicaciones , Ratones , Ratas , Ratas Sprague-Dawley , Uremia/metabolismo , Uremia/patología , Calcificación Vascular/etiología
19.
Toxins (Basel) ; 14(6)2022 06 11.
Artículo en Inglés | MEDLINE | ID: mdl-35737063

RESUMEN

In patients with severe kidney disease, renal clearance is compromised, resulting in the accumulation of a plethora of endogenous waste molecules that cannot be removed by current dialysis techniques, the most often applied treatment. These uremic retention solutes, also named uremic toxins, are a heterogeneous group of organic compounds of which many are too large to be filtered and/or are protein-bound. Their renal excretion depends largely on renal tubular secretion, by which the binding is shifted towards the free fraction that can be eliminated. To facilitate this process, kidney proximal tubule cells are equipped with a range of transport proteins that cooperate in cellular uptake and urinary excretion. In recent years, innovations in dialysis techniques to advance uremic toxin removal, as well as treatments with drugs and/or dietary supplements that limit uremic toxin production, have provided some clinical improvements or are still in progress. This review gives an overview of these developments. Furthermore, the role protein-bound uremic toxins play in inter-organ communication, in particular between the gut (the side where toxins are produced) and the kidney (the side of their removal), is discussed.


Asunto(s)
Toxinas Biológicas , Uremia , Humanos , Riñón/metabolismo , Diálisis Renal/métodos , Toxinas Biológicas/metabolismo , Uremia/metabolismo , Tóxinas Urémicas
20.
Mol Biol Rep ; 49(8): 8139-8143, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-35661049

RESUMEN

Acetaminophen (APAP) is commonly prescribed as an antipyretic and analgesic agent in the practical field. Like every other drug(s), APAP also undergo metabolism by oxidation or conjugation by glucuronate and sulphate to form the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI). Moreover, the NAPQI is detoxified by conjugation with reduced glutathione (GSH). Interestingly, APAP is also metabolized in the kidney by deacetylation reaction in the presence of N-deacetylase enzyme into another severely toxic but minor metabolite, p-aminophenol. Both NAPQI and p-aminophenol shows nephrotoxicity as well as hepatotoxicity. Hence, the long-term therapeutic dose use and unnecessary overdose of APAP are of great concern as prolonged negligence may cost the nephrotoxicity that may lead to uremia and finally to kidney failure. It has recently been investigated that probiotic supplementation inhibits the sequential events associated with APAP-induced nephrotoxicity. This review emphasizes the role of different probiotics that have already been investigated in nephrotoxicity or uremia caused by APAP overdose.


Asunto(s)
Probióticos , Insuficiencia Renal , Uremia , Acetaminofén/efectos adversos , Glutatión/metabolismo , Humanos , Probióticos/uso terapéutico , Uremia/metabolismo
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