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Fularski P, Czarnik W, Frankenstein H, Gąsior M, Młynarska E, Rysz J, Franczyk B. Unveiling Selected Influences on Chronic Kidney Disease Development and Progression. Cells 2024; 13:751. [PMID: 38727287 PMCID: PMC11083010 DOI: 10.3390/cells13090751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 04/14/2024] [Accepted: 04/16/2024] [Indexed: 05/13/2024] Open
Abstract
Currently, more and more people are suffering from chronic kidney disease (CKD). It is estimated that CKD affects over 10% of the population worldwide. This is a significant issue, as the kidneys largely contribute to maintaining homeostasis by, among other things, regulating blood pressure, the pH of blood, and the water-electrolyte balance and by eliminating unnecessary metabolic waste products from blood. What is more, this disease does not show any specific symptoms at the beginning. The development of CKD is predisposed by certain conditions, such as diabetes mellitus or hypertension. However, these disorders are not the only factors promoting the onset and progression of CKD. The primary purpose of this review is to examine renin-angiotensin-aldosterone system (RAAS) activity, transforming growth factor-β1 (TGF-β1), vascular calcification (VC), uremic toxins, and hypertension in the context of their impact on the occurrence and the course of CKD. We firmly believe that a deeper comprehension of the cellular and molecular mechanisms underlying CKD can lead to an enhanced understanding of the disease. In the future, this may result in the development of medications targeting specific mechanisms involved in the decline of kidney function. Our paper unveils the selected processes responsible for the deterioration of renal filtration abilities.
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Affiliation(s)
- Piotr Fularski
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland (M.G.)
| | - Witold Czarnik
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland (M.G.)
| | - Hanna Frankenstein
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland (M.G.)
| | - Magdalena Gąsior
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland (M.G.)
| | - Ewelina Młynarska
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland (M.G.)
| | - Jacek Rysz
- Department of Nephrology, Hypertension and Family Medicine, University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland
| | - Beata Franczyk
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland (M.G.)
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Schildboeck C, Harm S, Hartmann J. In vitro Removal of Protein-Bound Retention Solutes by Extracorporeal Blood Purification Procedures. Blood Purif 2024; 53:231-242. [PMID: 38262384 DOI: 10.1159/000534906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 10/26/2023] [Indexed: 01/25/2024]
Abstract
INTRODUCTION When the kidneys or liver fail, toxic metabolites accumulate in the patient's blood, causing cardiovascular and neurotoxic complications and increased mortality. Conventional membrane-based extracorporeal blood purification procedures cannot remove these toxins efficiently. The aim of this in vitro study was to determine whether commercial hemoperfusion adsorbers are suitable for removing protein-bound retention solutes from human plasma and whole blood as well as to compare the removal to conventional hemodialysis. METHODS For in vitro testing of the removal of protein-bound substances, whole blood and plasma were spiked with uremic retention solutes (homocysteine, hippuric acid, indoxyl sulfate, 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid) and the toxins of liver failure (bilirubin, cholic acid, tryptophan, phenol). Subsequently, the protein binding of each retention solute was determined. The adsorption characteristics of the hemoperfusion adsorbers, Jafron HA and Biosky MG, both approved for the adsorption of protein-bound uremic retention solutes and Cytosorb, an adsorber recommended for adsorption of cytokines, were tested by incubating them in spiked whole blood or plasma for 1 h. Subsequently, the adsorption characteristics of the adsorbers were tested in a dynamic system. For this purpose, a 6-h in vitro hemoperfusion treatment was compared with an equally long in vitro hemodialysis treatment. RESULTS Hippuric acid, homocysteine, indoxyl sulfate, and tryptophan were most effectively removed by hemodialysis. Bilirubin and cholic acid were removed best by hemoperfusion with Cytosorb. A treatment with Jafron HA and Biosky MG showed similar results for the adsorption of the tested retention solutes and were best for removing phenol. 3-Carboxy-4-methyl-5-propyl-2-furanpropionic acid could not be removed with any treatment method. DISCUSSION/CONCLUSION A combination of hemodialysis with hemoperfusion seems promising to improve the removal of some toxic metabolites in extracorporeal therapies. However, some very strongly protein-bound metabolites cannot be removed adequately with the adsorbers tested.
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Affiliation(s)
- Claudia Schildboeck
- Department for Biomedical Research, University for Continuing Education Krems, Krems, Austria
| | - Stephan Harm
- Department for Biomedical Research, University for Continuing Education Krems, Krems, Austria
| | - Jens Hartmann
- Department for Biomedical Research, University for Continuing Education Krems, Krems, Austria
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Dehghan Niestanak V, Unsworth LD. Detailing Protein-Bound Uremic Toxin Interaction Mechanisms with Human Serum Albumin in the Pursuit of Designing Competitive Binders. Int J Mol Sci 2023; 24:ijms24087452. [PMID: 37108613 PMCID: PMC10139063 DOI: 10.3390/ijms24087452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/12/2023] [Accepted: 04/15/2023] [Indexed: 04/29/2023] Open
Abstract
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.
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Affiliation(s)
- Vida Dehghan Niestanak
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB T6G 2G4, Canada
| | - Larry D Unsworth
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
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Ding W, Ding S, Meng Z, Wang X. Hierarchically structural polyacrylonitrile/
MIL
‐101(Cr) nanofibrous membranes with super adsorption performance for indoxyl sulfate. J Appl Polym Sci 2022. [DOI: 10.1002/app.53399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Weihong Ding
- State Key Lab for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering Donghua University Shanghai China
| | - Siping Ding
- State Key Lab for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering Donghua University Shanghai China
| | - Zheyi Meng
- State Key Lab for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering Donghua University Shanghai China
| | - Xuefen Wang
- State Key Lab for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering Donghua University Shanghai China
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Cerebrovascular Disease, Cardiovascular Disease, and Chronic Kidney Disease: Interplays and Influences. Curr Neurol Neurosci Rep 2022; 22:757-766. [PMID: 36181576 DOI: 10.1007/s11910-022-01230-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/26/2022] [Indexed: 01/27/2023]
Abstract
PURPOSE OF REVIEW We reviewed reasons for the high cardiovascular risk (CVD) of patients with chronic kidney disease (CKD), and explored alternatives to treatment of traditional risk factors to reduce CVD in CKD. RECENT FINDINGS Besides traditional risk factors, patients with CKD are exposed to uremic toxins of two kinds: systemically derived toxins include asymmetric dimethylarginine (ADMA), total homocysteine (tHcy), thiocyanate, tumor necrosis factor alpha, and interleukin 6. Gut-derived uremic toxins (GDUT), products of the intestinal microbiome, include hippuric acid, indoxyl sulfate, p-cresyl sulfate, p-cresyl glucuronide, phenylacetylglutamine, and trimethylamine N-oxide (TMAO). Cyanocobalamin is toxic in patients with CKD. Approaches to reducing plasma levels of these uremic toxins would include diet to reduce GDUT, kidney transplantation, more intensive dialysis, and vitamin therapy to lower tHcy with methylcobalamin rather than cyanocobalamin. The high CVD risk in CKD requires consideration of therapies beyond treatment of traditional risk factors.
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Production of Indole and Indole-Related Compounds by the Intestinal Microbiota and Consequences for the Host: The Good, the Bad, and the Ugly. Microorganisms 2022; 10:microorganisms10050930. [PMID: 35630374 PMCID: PMC9145683 DOI: 10.3390/microorganisms10050930] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/19/2022] [Accepted: 04/26/2022] [Indexed: 02/06/2023] Open
Abstract
The intestinal microbiota metabolic activity towards the available substrates generates myriad bacterial metabolites that may accumulate in the luminal fluid. Among them, indole and indole-related compounds are produced by specific bacterial species from tryptophan. Although indole-related compounds are, first, involved in intestinal microbial community communication, these molecules are also active on the intestinal mucosa, exerting generally beneficial effects in different experimental situations. After absorption, indole is partly metabolized in the liver into the co-metabolite indoxyl sulfate. Although some anti-inflammatory actions of indole on liver cells have been shown, indoxyl sulfate is a well-known uremic toxin that aggravates chronic kidney disease, through deleterious effects on kidney cells. Indoxyl sulfate is also known to provoke endothelial dysfunction. Regarding the central nervous system, emerging research indicates that indole at excessive concentrations displays a negative impact on emotional behavior. The indole-derived co-metabolite isatin appears, in pre-clinical studies, to accumulate in the brain, modulating brain function either positively or negatively, depending on the doses used. Oxindole, a bacterial metabolite that enters the brain, has shown deleterious effects on the central nervous system in experimental studies. Lastly, recent studies performed with indoxyl sulfate report either beneficial or deleterious effects depending once again on the dose used, with missing information on the physiological concentrations that are reaching the central nervous system. Any intervention aiming at modulating indole and indole-related compound concentrations in the biological fluids should crucially take into account the dual effects of these compounds according to the host tissues considered.
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Szymaszek P, Fiedor P, Chachaj-Brekiesz A, Tyszka-Czochara M, Świergosz T, Ortyl J. Molecular interactions of bovine serum albumin (BSA) with pyridine derivatives as candidates for non-covalent protein probes: a spectroscopic investigation. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118262] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Berg AH, Kumar S, Karumanchi SA. Indoxyl sulfate in uremia: an old idea with updated concepts. J Clin Invest 2022; 132:155860. [PMID: 34981787 PMCID: PMC8718144 DOI: 10.1172/jci155860] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Patients with end-stage kidney disease (ESKD) have increased vascular disease. While protein-bound molecules that escape hemodialysis may contribute to uremic toxicity, specific contributing toxins remain ambiguous. In this issue of the JCI, Arinze et al. explore the role of tryptophan metabolites in chronic kidney disease–associated (CKD-associated) peripheral arterial disease. The authors used mouse and zebrafish models to show that circulating indoxyl sulfate (IS) blocked endothelial Wnt signaling, which impaired angiogenesis. Plasma levels of IS and other tryptophan metabolites correlated with adverse peripheral vascular disease events in humans. These findings suggest that lowering IS may benefit individuals with CKD and ESKD.
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Affiliation(s)
| | - Sanjeev Kumar
- Medicine and Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - S Ananth Karumanchi
- Medicine and Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Deparment of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
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Bowry SK, Kotanko P, Himmele R, Tao X, Anger M. The membrane perspective of uraemic toxins: which ones should, or can, be removed? Clin Kidney J 2021; 14:i17-i31. [PMID: 34987783 PMCID: PMC8711755 DOI: 10.1093/ckj/sfab202] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Indexed: 11/15/2022] Open
Abstract
Informed decision-making is paramount to the improvement of dialysis therapies and patient outcomes. A cornerstone of delivery of optimal dialysis therapy is to delineate which substances (uraemic retention solutes or 'uraemic toxins') contribute to the condition of uraemia in terms of deleterious biochemical effects they may exert. Thereafter, decisions can be made as to which of the accumulated compounds need to be targeted for removal and by which strategies. For haemodialysis (HD), the non-selectivity of membranes is sometimes considered a limitation. Yet, considering that dozens of substances with potential toxicity need to be eliminated, and targeting removal of individual toxins explicitly is not recommended, current dialysis membranes enable elimination of several molecules of a broad size range within a single therapy session. However, because HD solute removal is based on size-exclusion principles, i.e. the size of the substances to be removed relative to the mean size of the 'pores' of the membrane, only a limited degree of selectivity of removal is possible. Removal of unwanted substances during HD needs to be weighed against the unavoidable loss of substances that are recognized to be necessary for bodily functions and physiology. In striving to improve the efficiency of HD by increasing the porosity of membranes, there is a greater potential for the loss of substances that are of benefit. Based on this elementary trade-off and availability of recent guidance on the relative toxicity of substances retained in uraemia, we propose a new evidence-linked uraemic toxin elimination (ELUTE) approach whereby only those clusters of substances for which there is a sufficient body of evidence linking them to deleterious biological effects need to be targeted for removal. Our approach involves correlating the physical properties of retention solutes (deemed to express toxicity) with key determinants of membranes and separation processes. Our analysis revealed that in attempting to remove the relatively small number of 'larger' substances graded as having only moderate toxicity, uncontrolled (and efficient) removal of several useful compounds would take place simultaneously and may compromise the well-being or outcomes of patients. The bulk of the uraemic toxin load comprises uraemic toxins below <30 000 Da and are adequately removed by standard membranes. Further, removal of a few difficult-to-remove-by-dialysis (protein-bound) compounds that express toxicity cannot be achieved by manipulation of pore size alone. The trade-off between the benefits of effective removal of the bulk of the uraemic toxin load and risks (increased loss of useful substances) associated with targeting the removal of a few larger substances in 'high-efficiency' HD treatment strategies needs to be recognized and better understood. The removability during HD of substances, be they toxic, inert or beneficial, needs be revised to establish the pros and cons of current dialytic elimination strategies. .
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Affiliation(s)
- Sudhir K Bowry
- Dialysis-at-Crossroads (D@X) Advisory, Bad Nauheim, Germany
| | | | - Rainer Himmele
- Global Medical Information and Education, Fresenius Medical Care, Charlotte, NC, USA
| | - Xia Tao
- Renal Research Institute, New York, NY, USA
| | - Michael Anger
- Global Medical Office, Fresenius Medical Care, Waltham, MA, USA
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10
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Lisowska-Myjak B, Zborowska H, Jaźwiec R, Karlińska M, Skarżyńska E. Serum indoxyl sulphate and its relation to albumin and α1-acid glycoprotein as a potential biomarkers of maternal intestinal metabolism during pregnancy and postpartum. PLoS One 2021; 16:e0259501. [PMID: 34739491 PMCID: PMC8570491 DOI: 10.1371/journal.pone.0259501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 10/20/2021] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Serum indoxyl sulfate (IS) levels depend on the production of indole in the gut. The biological effects of IS in the vascular bed could be confirmed by changes in the levels of individual serum proteins during normal pregnancy and in the postpartum period as compared with non-pregnant controls. Albumin (Alb) and α1-acid glycoprotein (AGP, orosomucoid) are the most abundant serum carrier proteins with potential interrelationships with serum levels of IS. METHODS Serum levels of IS, Alb and AGP were measured in 84 pregnant women in the first, second and third trimester of pregnancy and in the postpartum period, as well as in non-pregnant controls (n = 20), using ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry (IS), colorimetric assay (Alb) and immunoturbidimetric assay (AGP). RESULTS The postpartum serum levels [mg/L] of IS were lower (p = 0.027) than in the second trimester (mean±SD: 0.85±0.39 vs 0.58±0.32). There were no differences in the IS to ALB ratio calculated in the three trimesters of pregnancy, the postpartum period, and in the non-pregnant controls. The IS/AGP ratio increased from the first to the second trimester (p = 0.039), and decreased in the postpartum period (p<0.05), when it was lower than in the second and third trimester. CONCLUSIONS The variability of the serum IS/AGP ratio during pregnancy and in the postpartum period may reflect shared involvement in the regulation of their intravascular relationships. The link between serum levels of IS derived from the gut and AGP could serve a potential biomarkers of maternal intestinal metabolism during pregnancy and postpartum.
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Affiliation(s)
- Barbara Lisowska-Myjak
- Department of Biochemistry and Clinical Chemistry, Medical University of Warsaw, Warsaw, Poland
| | - Hanna Zborowska
- Department of Laboratory Diagnostics, Medical University of Warsaw, Warsaw, Poland
| | - Radosław Jaźwiec
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Maria Karlińska
- Department of Medical Informatics and Telemedicine, Medical University of Warsaw, Warsaw, Poland
| | - Ewa Skarżyńska
- Department of Biochemistry and Clinical Chemistry, Medical University of Warsaw, Warsaw, Poland
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Abstract
PURPOSE OF REVIEW Improvement in hemodialysis treatment and membrane technology are focused on two aims: the first one is to achieve a better control of circulating uremic solutes by enhancing removal capacity and by broadening molecular weight spectrum of solutes cleared; the second one is to prevent inflammation by improving hemocompatibility of the global dialysis system. RECENT FINDINGS Despite impressive progresses in polymers chemistry few hazards are still remaining associated with leaching or sensitization to polymer additives. Research has focused on developing more stable polymers by means of additives or processes aiming to minimize such risks. Membrane engineering manufacturing with support of nanocontrolled spinning technology has opened up membrane to middle and large molecular weight substances, while preserving albumin losses. Combination of diffusive and enhanced convective fluxes in the same hemodialyzer module, namely hemodiafiltration, provides today the highest solute removal capacity over a broad spectrum of solutes. SUMMARY Dialysis membrane is a crucial component of the hemodialysis system to optimize solute removal efficacy and to minimize blood membrane biological reactions. Hemodialyzer is much more than a membrane. Dialysis membrane and hemodialyzer choice are parts of a treatment chain that should be operated in optimized conditions and adjusted to patient needs and tolerance, to improve patient outcomes.
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Affiliation(s)
- Bernard Canaud
- Global Medical Office, FMC Deutschland, Bad Homburg, Germany
- University of Montpellier, UFR of Medicine, Montpellier, France
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Challenges of reducing protein-bound uremic toxin levels in chronic kidney disease and end stage renal disease. Transl Res 2021; 229:115-134. [PMID: 32891787 DOI: 10.1016/j.trsl.2020.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 08/24/2020] [Accepted: 09/02/2020] [Indexed: 12/11/2022]
Abstract
The prevalence of chronic kidney disease (CKD) in the worldwide population is currently estimated between 11% and 13%. Adequate renal clearance is compromised in these patients and the accumulation of a large number of uremic retention solutes results in an irreversible worsening of renal function which can lead to end stage renal disease (ESRD). Approximately three million ESRD patients currently receive renal replacement therapies (RRTs), such as hemodialysis, which only partially restore kidney function, as they are only efficient in removing mainly small, unbound solutes from the circulation while leaving larger and protein-bound uremic toxins (PBUTs) untouched. The accumulation of PBUTs in patients highly increases the risk of cardiovascular events and is associated with higher mortality and morbidity in CKD and ESRD. In this review, we address several strategies currently being explored toward reducing PBUT concentrations, including clinical and medical approaches, therapeutic techniques, and recent developments in RRT technology. These include preservation of renal function, limitation of colon derived PBUTs, oral sorbents, adsorbent RRT technology, and use of albumin displacers. Despite the promising results of the different approaches to promote enhanced removal of a small percentage of the more than 30 identified PBUTs, on their own, none of them provide a treatment with the required efficiency, safety and cost-effectiveness to prevent CKD-related complications and decrease mortality and morbidity in ESRD.
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Uremic Toxins in the Progression of Chronic Kidney Disease and Cardiovascular Disease: Mechanisms and Therapeutic Targets. Toxins (Basel) 2021; 13:toxins13020142. [PMID: 33668632 PMCID: PMC7917723 DOI: 10.3390/toxins13020142] [Citation(s) in RCA: 119] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 12/24/2022] Open
Abstract
Chronic kidney disease (CKD) is a progressive loss of renal function. The gradual decline in kidney function leads to an accumulation of toxins normally cleared by the kidneys, resulting in uremia. Uremic toxins are classified into three categories: free water-soluble low-molecular-weight solutes, protein-bound solutes, and middle molecules. CKD patients have increased risk of developing cardiovascular disease (CVD), due to an assortment of CKD-specific risk factors. The accumulation of uremic toxins in the circulation and in tissues is associated with the progression of CKD and its co-morbidities, including CVD. Although numerous uremic toxins have been identified to date and many of them are believed to play a role in the progression of CKD and CVD, very few toxins have been extensively studied. The pathophysiological mechanisms of uremic toxins must be investigated further for a better understanding of their roles in disease progression and to develop therapeutic interventions against uremic toxicity. This review discusses the renal and cardiovascular toxicity of uremic toxins indoxyl sulfate, p-cresyl sulfate, hippuric acid, TMAO, ADMA, TNF-α, and IL-6. A focus is also placed on potential therapeutic targets against uremic toxicity.
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Smith J, Pfaendtner J. Elucidating the Molecular Interactions between Uremic Toxins and the Sudlow II Binding Site of Human Serum Albumin. J Phys Chem B 2020; 124:3922-3930. [DOI: 10.1021/acs.jpcb.0c02015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Josh Smith
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195-1750, United States
| | - Jim Pfaendtner
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195-1750, United States
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Gut microbiota and chronic kidney disease: evidences and mechanisms that mediate a new communication in the gastrointestinal-renal axis. Pflugers Arch 2020; 472:303-320. [PMID: 32064574 DOI: 10.1007/s00424-020-02352-x] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 01/06/2020] [Accepted: 01/21/2020] [Indexed: 02/06/2023]
Abstract
Chronic kidney disease (CKD) represents a growing public health problem associated with loss of kidney function and cardiovascular disease (CVD), the main leading cause of morbidity and mortality in CKD. It is well established that CKD is associated with gut dysbiosis. Over the past few years, there has been a growing interest in studying the composition of the gut microbiota in patients with CKD as well as the mechanisms by which gut dysbiosis contributes to CKD progression, in order to identify possible therapeutic targets to improve the morbidity and survival in CKD. The purpose of this review is to explore the clinical evidence and the mechanisms involved in the gut-kidney crosstalk as well as the possible interventions to restore a normal balance of the gut microbiota in CKD. It is well known that the influence of the gut microbiota on the gut-kidney axis acts in a reciprocal way: on the one hand, CKD significantly modifies the composition and functions of the gut microbiota. On the other hand, gut microbiota is able to manipulate the processes leading to CKD onset and progression through inflammatory, endocrine, and neurologic pathways. Understanding the complex interaction between these two organs (gut microbiota and kidney) may provide novel nephroprotective interventions to prevent the progression of CKD by targeting the gut microbiota. The review is divided into three main sections: evidences from clinical studies about the existence of a gut microbiota dysbiosis in CKD; the complex mechanisms that explain the bidirectional relationship between CKD and gut dysbiosis; and reports regarding the effects of prebiotic, probiotic, and synbiotic supplementation to restore gut microbiota balance in CKD.
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Xu X, Angioletti-Uberti S, Lu Y, Dzubiella J, Ballauff M. Interaction of Proteins with Polyelectrolytes: Comparison of Theory to Experiment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5373-5391. [PMID: 30095921 DOI: 10.1021/acs.langmuir.8b01802] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We discuss recent investigations of the interaction of polyelectrolytes with proteins. In particular, we review our recent studies on the interaction of simple proteins such as human serum albumin (HSA) and lysozyme with linear polyelectrolytes, charged dendrimers, charged networks, and polyelectrolyte brushes. In all cases discussed here, we combined experimental work with molecular dynamics (MD) simulations and mean-field theories. In particular, isothermal titration calorimetry (ITC) has been employed to obtain the respective binding constants Kb and the Gibbs free energy of binding. MD simulations with explicit counterions but implicit water demonstrate that counterion release is the main driving force for the binding of proteins to strongly charged polyelectrolytes: patches of positive charges located on the surface of the protein become multivalent counterions of the polyelectrolyte, thereby releasing a number of counterions condensed on the polyelectrolyte. The binding Gibbs free energy due to counterion release is predicted to scale with the logarithm of the salt concentration in the system, which is verified by both simulations and experiment. In several cases, namely, for the interaction of proteins with linear polyelectrolytes and highly charged hydrophilic dendrimers, the binding constant could be calculated from simulations to very good approximation. This finding demonstrated that in these cases explicit hydration effects do not contribute to the Gibbs free energy of binding. The Gibbs free energy can also be used to predict the kinetics of protein uptake by microgels for a given system by applying dynamic density functional theory. The entire discussion demonstrates that the direct comparison of theory with experiments can lead to a full understanding of the interaction of proteins with charged polymers. Possible implications for applications, such as drug design, are discussed.
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Affiliation(s)
- Xiao Xu
- School of Chemical Engineering , Nanjing University of Science and Technology , 200 Xiao Ling Wei , Nanjing 210094 , P. R. China
| | - Stefano Angioletti-Uberti
- Department of Materials , Imperial College London , London SW7 2AZ - UK , U.K
- International Research Centre for Soft Matter , Beijing University of Chemical Technology , 100099 Beijing , PR China
| | - Yan Lu
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Institute of Chemistry , University of Potsdam , 14467 Potsdam , Germany
| | - Joachim Dzubiella
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Physikalisches Institut , Albert-Ludwigs-Universität , 79104 Freiburg , Germany
| | - Matthias Ballauff
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Institut für Physik , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
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Madero M, Cano KB, Campos I, Tao X, Maheshwari V, Brown J, Cornejo B, Handelman G, Thijssen S, Kotanko P. Removal of Protein-Bound Uremic Toxins during Hemodialysis Using a Binding Competitor. Clin J Am Soc Nephrol 2019; 14:394-402. [PMID: 30755453 PMCID: PMC6419294 DOI: 10.2215/cjn.05240418] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 01/03/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND OBJECTIVES Current hemodialysis techniques fail to efficiently remove the protein-bound uremic toxins p-cresyl sulfate and indoxyl sulfate due to their high degree of albumin binding. Ibuprofen, which shares the same primary albumin binding site with p-cresyl sulfate and indoxyl sulfate, can be infused during hemodialysis to displace these toxins, thereby augmenting their removal. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We infused 800 mg ibuprofen into the arterial bloodline between minutes 21 and 40 of a conventional 4-hour high-flux hemodialysis treatment. We measured arterial, venous, and dialysate outlet concentrations of indoxyl sulfate, p-cresyl sulfate, tryptophan, ibuprofen, urea, and creatinine before, during, and after the ibuprofen infusion. We report clearances of p-cresyl sulfate and indoxyl sulfate before and during ibuprofen infusion and dialysate concentrations of protein-bound uremic toxins normalized to each patient's average preinfusion concentrations. RESULTS We studied 18 patients on maintenance hemodialysis: age 36±11 years old, ten women, and mean vintage of 37±37 months. Compared with during the preinfusion period, the median (interquartile range) clearances of indoxyl sulfate and p-cresyl sulfate increased during ibuprofen infusion from 6.0 (6.5) to 20.2 (27.1) ml/min and from 4.4 (6.7) to 14.9 (27.1) ml/min (each P<0.001), respectively. Relative median (interquartile range) protein-bound uremic toxin dialysate outlet levels increased from preinfusion 1.0 (reference) to 2.4 (1.2) for indoxyl sulfate and to 2.4 (1.0) for p-cresyl sulfate (each P<0.001). Although median serum post- and predialyzer levels in the preinfusion period were similar, infusion led to a marked drop in serum postdialyzer levels for both indoxyl sulfate and p-cresyl sulfate (-1.0 and -0.3 mg/dl, respectively; each P<0.001). The removal of the nonprotein-bound solutes creatinine and urea was not increased by the ibuprofen infusion. CONCLUSIONS Infusion of ibuprofen into the arterial bloodline during hemodialysis significantly increases the dialytic removal of indoxyl sulfate and p-cresyl sulfate and thereby, leads to greater reduction in their serum levels.
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Affiliation(s)
- Magdalena Madero
- Division of Nephrology, Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de Mexico, Mexico
| | - Karla B. Cano
- Division of Nephrology, Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de Mexico, Mexico
| | - Israel Campos
- Renal Research Institute, Research Division, New York, New York
| | - Xia Tao
- Renal Research Institute, Research Division, New York, New York
| | | | - Jillian Brown
- Biomedical and Nutritional Sciences, University of Massachusetts, Lowell, Massachusetts; and
| | - Beatriz Cornejo
- Division of Nephrology, Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de Mexico, Mexico
| | - Garry Handelman
- Biomedical and Nutritional Sciences, University of Massachusetts, Lowell, Massachusetts; and
| | | | - Peter Kotanko
- Renal Research Institute, Research Division, New York, New York
- Department of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York
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Kemp JA, Esgalhado M, Macedo RA, Regis B, Damasceno NRT, da Silva Torres EAF, Gonçalinho GHF, Borges NA, Nakao LS, Fouque D, Mafra D. A possible link between polyunsaturated fatty acids and uremic toxins from the gut microbiota in hemodialysis patients: A hypothesis. Hemodial Int 2019; 23:189-197. [PMID: 30779317 DOI: 10.1111/hdi.12725] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/30/2018] [Accepted: 12/06/2018] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Indoxyl sulfate (IS) and p-cresyl sulfate (p-CS) are albumin-bound uremic toxins that are difficult to remove by hemodialysis (HD). Human serum albumin (HSA) carries several compounds, including fatty acids that can bind to site II of HSA and represent competing ligands for uremic toxins. The aim of this study was to investigate the association between fatty acids and uremic toxin plasma levels in patients undergoing HD. METHODS Thirty-three HD patients (51.5% male, 54.9 ± 10.2 years old, 44.63 ± 28.4 months on HD, albumin level of 3.8 ± 0.3 g/dL) were evaluated. The erythrocyte fatty acid content (saturated fatty acid [SFA], monounsaturated fatty acid [MUFA], and polyunsaturated fatty acid [PUFA]) was measured by gas chromatography, and total IS and p-CS plasma levels were measured by reversed-phase high-performance liquid chromatography. FINDINGS The mean percentages of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) + DHA and gamma-linolenic (GLA) acid in the erythrocyte membrane were 1.35% ± 0.74%, 1.85% ± 0.79%, and 0.33% ± 0.26%, respectively. The mean levels of IS and p-CS were 19.4 ± 11.9 mg/dL and 101.5 ± 57.2 mg/dL, respectively. There was no significant association between SFA and MUFA and IS and p-CS; however, a negative correlation was found between p-CS and specific PUFAs, and the association between GLA and p-CS levels was retained after adjusting for potential confounding variables (β = -0.49, P = 0.007). DISCUSSION Polyunsaturated fatty acids may contribute to the decrease in p-CS uremic toxin plasma levels in patients with chronic kidney disease undergoing HD.
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Affiliation(s)
- Julie Ann Kemp
- Post-Graduate Program in Medical Sciences, Federal University Fluminense (UFF), Niterói, Rio de Janeiro, Brazil
| | - Marta Esgalhado
- Post-Graduate Program in Cardiovascular Sciences, Federal University Fluminense (UFF), Niterói, Rio de Janeiro, Brazil
| | - Renata Azevedo Macedo
- Post-Graduate Program in Cardiovascular Sciences, Federal University Fluminense (UFF), Niterói, Rio de Janeiro, Brazil
| | - Bruna Regis
- Post-Graduate Program in Medical Sciences, Federal University Fluminense (UFF), Niterói, Rio de Janeiro, Brazil
| | | | | | | | - Natália Alvarenga Borges
- Post-Graduate Program in Cardiovascular Sciences, Federal University Fluminense (UFF), Niterói, Rio de Janeiro, Brazil
| | - Lia Sumie Nakao
- Basic Pathology Department, Federal University of Paraná (UFPR), Curitiba, Puerto Rico, Brazil
| | - Denis Fouque
- Department of Nephrology, Centre Hopitalier Lyon Sud, INSERM 1060, CENS, Université de Lyon, France
| | - Denise Mafra
- Post-Graduate Program in Medical Sciences, Federal University Fluminense (UFF), Niterói, Rio de Janeiro, Brazil.,Post-Graduate Program in Cardiovascular Sciences, Federal University Fluminense (UFF), Niterói, Rio de Janeiro, Brazil
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In silico comparison of protein-bound uremic toxin removal by hemodialysis, hemodiafiltration, membrane adsorption, and binding competition. Sci Rep 2019; 9:909. [PMID: 30696874 PMCID: PMC6351554 DOI: 10.1038/s41598-018-37195-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 12/04/2018] [Indexed: 11/19/2022] Open
Abstract
Protein-bound uremic toxins (PBUTs) are poorly removed during hemodialysis (HD) due to their low free (dialyzable) plasma concentration. We compared PBUT removal between HD, hemodiafiltration (HDF), membrane adsorption, and PBUT displacement in HD. The latter involves infusing a binding competitor pre-dialyzer, which competes with PBUTs for their albumin binding sites and increases their free fraction. We used a mathematical model of PBUT/displacer kinetics in dialysis comprising a three-compartment patient model, an arterial/venous tube segment model, and a dialyzer model. Compared to HD, improvements in removal of prototypical PBUTs indoxyl sulfate (initial concentration 100 µM, 7% free) and p-cresyl sulfate (150 µM, 5% free) were: 5.5% and 6.4%, respectively, for pre-dilution HDF with 20 L replacement fluid; 8.1% and 9.1% for post-dilution HDF 20 L; 15.6% and 18.3% for pre-dilution HDF 60 L; 19.4% and 22.2% for complete membrane adsorption; 35.0% and 41.9% for displacement with tryptophan (2000 mg in 500 mL saline); 26.7% and 32.4% for displacement with ibuprofen (800 mg in 200 mL saline). Prolonged (one-month) use of tryptophan reduces the IS and pCS time-averaged concentration by 28.1% and 29.9%, respectively, compared to conventional HD. We conclude that competitive binding can be a pragmatic approach for improving PBUT removal.
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20
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Ooi CH, Ling YP, Pung SY, Yeoh FY. Mesoporous hydroxyapatite derived from surfactant-templating system for p-Cresol adsorption: Physicochemical properties, formation process and adsorption performance. POWDER TECHNOL 2019. [DOI: 10.1016/j.powtec.2018.10.043] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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21
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Yu S, Kent B, Jafta CJ, Petzold A, Radulescu A, Schuchardt M, Tölle M, van der Giet M, Zidek W, Ballauff M. Stability of human serum albumin structure upon toxin uptake explored by small angle neutron scattering. POLYMER 2018. [DOI: 10.1016/j.polymer.2018.02.060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Li J, Han L, Liu S, He S, Cao Y, Xie J, Jia L. Removal of indoxyl sulfate by water-soluble poly-cyclodextrins in dialysis. Colloids Surf B Biointerfaces 2018; 164:406-413. [DOI: 10.1016/j.colsurfb.2018.01.056] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 01/05/2018] [Accepted: 01/27/2018] [Indexed: 10/18/2022]
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23
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Evaluation of the Toxin-to-Protein Binding Rates during Hemodialysis Using Sorbent-Loaded Mixed-Matrix Membranes. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8040536] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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24
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Maheshwari V, Thijssen S, Tao X, Fuertinger D, Kappel F, Kotanko P. A novel mathematical model of protein-bound uremic toxin kinetics during hemodialysis. Sci Rep 2017; 7:10371. [PMID: 28871178 PMCID: PMC5583320 DOI: 10.1038/s41598-017-10981-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 08/10/2017] [Indexed: 11/17/2022] Open
Abstract
Protein-bound uremic toxins (PBUTs) are difficult to remove by conventional hemodialysis; a high degree of protein binding reduces the free fraction of toxins and decreases their diffusion across dialyzer membranes. Mechanistic understanding of PBUT kinetics can open new avenues to improve their dialytic removal. We developed a comprehensive model of PBUT kinetics that comprises: (1) a three-compartment patient model, (2) a dialyzer model. The model accounts for dynamic equilibrium between protein, toxin, and the protein-toxin complex. Calibrated and validated using clinical and experimental data from the literature, the model predicts key aspects of PBUT kinetics, including the free and bound concentration profiles for PBUTs and the effects of dialysate flow rate and dialyzer size on PBUT removal. Model simulations suggest that an increase in dialysate flow rate improves the reduction ratio (and removal) of strongly protein-bound toxins, namely, indoxyl sulfate and p-cresyl sulfate, while for weakly bound toxins, namely, indole-3-acetic acid and p-cresyl glucuronide, an increase in blood flow rate is advantageous. With improved dialyzer performance, removal of strongly bound PBUTs improves gradually, but marginally. The proposed model can be used for optimizing the dialysis regimen and for in silico testing of novel approaches to enhance removal of PBUTs.
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Affiliation(s)
| | | | - Xia Tao
- Renal Research Institute, New York, USA
| | | | - Franz Kappel
- Institute for Mathematics and Scientific Computing, University of Graz, Graz, Austria
| | - Peter Kotanko
- Renal Research Institute, New York, USA.,Icahn School of Medicine at Mount Sinai, New York, USA
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Chechłacz M, Korytowska N. ZWIĄZKI WIĄŻĄCE SIĘ Z BIAŁKAMI OSOCZA U LUDZI. ZNACZENIE W TERAPII ORAZ METODY OZNACZANIA WOLNEJ FRAKCJI. PROSPECTS IN PHARMACEUTICAL SCIENCES 2017. [DOI: 10.56782/pps.76] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Wiele substancji endogennych oraz egzogennych wykazuje zdolność do wiązania się z białkami osocza, głównie z ludzką albuminą surowicy oraz α-1-kwaśną glikoproteiną. Substancje te w krwioobiegu występują zarówno w formie wolnej jak i związanej z białkami. Białko posiada na swojej powierzchni miejsca wiązania charakterystyczne dla danego związku, różniące się wielkością, kształtem oraz powinowactwem. Wiązanie z białkami następuje w wyniku oddziaływań hydrofobowych, van der Waalsa oraz elektrostatycznych. Stopień związania z białkami osocza zależy od m.in. obecności stanu zapalnego, występowania chorób nerek i wątroby oraz wieku. Jedynie forma wolna związku jest aktywna biologicznie oraz jest zdolna do pokonywania barier biologicznych. W związku z tym duże znaczenie mają metody pomiaru stężenia frakcji niezwiązanej z białkami w osoczu. Najczęściej stosowana jest dializa równowagowa, uznawana za metodę referencyjną. Inne metody to m.in. ultrafiltracja, ultrawirowanie, mikrodializa, mikroekstrakcja, wysokosprawna analiza czołowa oraz ekstrakcja w punkcie zmętnienia.
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26
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Deltombe O, de Loor H, Glorieux G, Dhondt A, Van Biesen W, Meijers B, Eloot S. Exploring binding characteristics and the related competition of different protein-bound uremic toxins. Biochimie 2017; 139:20-26. [DOI: 10.1016/j.biochi.2017.05.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/16/2017] [Indexed: 11/25/2022]
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27
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Disposition and clinical implications of protein-bound uremic toxins. Clin Sci (Lond) 2017; 131:1631-1647. [DOI: 10.1042/cs20160191] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/10/2017] [Accepted: 04/11/2017] [Indexed: 12/11/2022]
Abstract
In patients with chronic kidney disease (CKD), adequate renal clearance is compromised, resulting in the accumulation of a plethora of uremic solutes. These uremic retention solutes, also named uremic toxins, are a heterogeneous group of organic compounds with intrinsic biological activities, many of which are too large to be filtered and/or are protein bound. The renal excretion of protein-bound toxins depends largely on active tubular secretion, which shifts the binding and allows for active secretion of the free fraction. To facilitate this process, renal proximal tubule cells are equipped with a range of transporters that co-operate in basolateral uptake and luminal excretion. Many of these transporters have been characterized as mediators of drug disposition, but have recently been recognized for their importance in the proximal renal tubular transport of uremic toxins as well. This also indicates that during uremia, drug disposition may be severely affected as a result of drug–uremic toxin interaction. In addition, CKD patients receive various drugs to treat their complications potentially resulting in drug–drug interactions (DDIs), also for drugs that are non-renally excreted. This review discusses the current knowledge on formation, disposition and removal of protein-bound uremic toxins. Furthermore, implications associated with drug treatment in kidney failure, as well as innovative renal replacement therapies targetting the protein-bound uremic toxins are being discussed. It will become clear that the complex problems associated with uremia warrant a transdisciplinary approach that unites research experts in the area of fundamental biomedical research with their colleagues in clinical nephrology.
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Favretto G, Souza LM, Gregório PC, Cunha RS, Maciel RAP, Sassaki GL, Toledo MG, Pecoits-Filho R, Souza WM, Stinghen AEM. Role of Organic Anion Transporters in the Uptake of Protein-Bound Uremic Toxins by Human Endothelial Cells and Monocyte Chemoattractant Protein-1 Expression. J Vasc Res 2017; 54:170-179. [PMID: 28472795 DOI: 10.1159/000468542] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 03/05/2017] [Indexed: 12/12/2022] Open
Abstract
Organic anion transporters (OATs) are involved in the uptake of uremic toxins such as p-cresyl sulfate (PCS) and indoxyl sulfate (IS), which play a role in endothelial dysfunction in patients with chronic kidney diseases (CKD). In this study, we investigated the role of OAT1 and OAT3 in the uptake of PCS and IS into human endothelial cells. PCS was synthesized via p-cresol sulfation and characterized using analytical methods. The cells were treated with PCS and IS in the absence and presence of probenecid (Pb), an OAT inhibitor. Cell viability was assessed using the MTT assay. The absorbed toxins were analyzed using chromatography, OAT expression using immunocytochemistry and western blot, and monocyte chemoattractant protein-1 (MCP-1) expression using enzyme-linked immunosorbent assay. Cell viability decreased after toxin treatment in a dose-dependent manner. PCS and IS showed significant internalization after 60 min treatment, while no internalization was observed in the presence of Pb, suggesting that OATs are involved in the transport of both toxins. Immunocytochemistry and western blot demonstrated OAT1 and OAT3 expression in endothelial cells. MCP-1 expression increased after toxins treatment but decreased after Pb treatment. PCS and IS uptake were mediated by OATs, and OAT blockage could serve as a therapeutic strategy to inhibit MCP-1 expression.
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Affiliation(s)
- Giane Favretto
- Experimental Nephrology Laboratory, Basic Pathology Department, Universidade Federal do Paraná, Curitiba, Brazil
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29
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Krieter DH, Devine E, Körner T, Rüth M, Wanner C, Raine M, Jankowski J, Lemke HD. Haemodiafiltration at increased plasma ionic strength for improved protein-bound toxin removal. Acta Physiol (Oxf) 2017; 219:510-520. [PMID: 27259463 DOI: 10.1111/apha.12730] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/01/2016] [Accepted: 05/31/2016] [Indexed: 11/27/2022]
Abstract
AIM Protein-bound uraemic toxin accumulation causes uraemia-associated cardiovascular morbidity. Enhancing the plasma ionic strength releases toxins from protein binding and makes them available for removal during dialysis. This concept was implemented through high sodium concentrations ([Na+ ]) in the substituate of pre-dilution haemodiafiltration at increased plasma ionic strength (HDF-IPIS). METHODS Ex vivo HDF-IPIS with blood tested increasing [Na+ ] to demonstrate efficacy and haemocompatibility. Haemocompatibility was further assessed in sheep using two different HDF-IPIS set-ups and [Na+ ] between 350 and 600 mmol L-1 . Safety and efficacy of para-cresyl sulphate (pCS) and indoxyl sulphate (IS) removal was further investigated in a randomized clinical pilot trial comparing HDF-IPIS to HD and HDF. RESULTS Compared to [Na+ ] of 150 mmol L-1 , ex vivo HDF-IPIS at 500 mmol L-1 demonstrated up to 50% higher IS removal. Haemolysis in sheep was low even at [Na+ ] of 600 mmol L-1 (free Hb 0.016 ± 0.001 g dL-1 ). In patients, compared to HD, a [Na+ ] of 240 mmol L-1 in HDF-IPIS resulted in 40% greater reduction (48.7 ± 23.6 vs. 67.8 ± 7.9%; P = 0.013) in free IS. Compared to HD and HDF (23.0 ± 14.8 and 25.4 ± 10.5 mL min-1 ), the dialytic clearance of free IS was 31.6 ± 12.8 mL min-1 (P = 0.017) in HDF-IPIS, but [Na+ ] in arterial blood increased from 132 ± 2 to 136 ± 3 mmol L-1 (0 vs. 240 min; P < 0.001). CONCLUSION HDF-IPIS is technically and clinically feasible. More effective HDF-IPIS requires higher temporary plasma [Na+ ], but dialysate [Na+ ] has to be appropriately adapted to avoid sodium accumulation.
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Affiliation(s)
- D. H. Krieter
- Division of Nephrology; Department of Medicine; University Hospital Würzburg; Würzburg Germany
| | | | - T. Körner
- Division of Nephrology; Department of Medicine; University Hospital Würzburg; Würzburg Germany
| | - M. Rüth
- eXcorLab GmbH; Obernburg Germany
| | - C. Wanner
- Division of Nephrology; Department of Medicine; University Hospital Würzburg; Würzburg Germany
| | - M. Raine
- eXcorLab GmbH; Obernburg Germany
| | - J. Jankowski
- Institute of Molecular Cardiovascular Research; University Hospital RWTH Aachen; Aachen Germany
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30
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Ellis RJ, Small DM, Vesey DA, Johnson DW, Francis R, Vitetta L, Gobe GC, Morais C. Indoxyl sulphate and kidney disease: Causes, consequences and interventions. Nephrology (Carlton) 2016; 21:170-7. [PMID: 26239363 DOI: 10.1111/nep.12580] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2015] [Indexed: 12/28/2022]
Abstract
In the last decade, chronic kidney disease (CKD), defined as reduced renal function (glomerular filtration rate (GFR) < 60 mL/min per 1.73 m(2) ) and/or evidence of kidney damage (typically manifested as albuminuria) for at least 3 months, has become one of the fastest-growing public health concerns worldwide. CKD is characterized by reduced clearance and increased serum accumulation of metabolic waste products (uremic retention solutes). At least 152 uremic retention solutes have been reported. This review focuses on indoxyl sulphate (IS), a protein-bound, tryptophan-derived metabolite that is generated by intestinal micro-organisms (microbiota). Animal studies have demonstrated an association between IS accumulation and increased fibrosis, and oxidative stress. This has been mirrored by in vitro studies, many of which report cytotoxic effects in kidney proximal tubular cells following IS exposure. Clinical studies have associated IS accumulation with deleterious effects, such as kidney functional decline and adverse cardiovascular events, although causality has not been conclusively established. The aims of this review are to: (i) establish factors associated with increased serum accumulation of IS; (ii) report effects of IS accumulation in clinical studies; (iii) critique the reported effects of IS in the kidney, when administered both in vivo and in vitro; and (iv) summarize both established and hypothetical therapeutic options for reducing serum IS or antagonizing its reported downstream effects in the kidney.
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Affiliation(s)
- Robert J Ellis
- Centre for Kidney Disease Research, Translational Research Institute, School of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - David M Small
- Centre for Kidney Disease Research, Translational Research Institute, School of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - David A Vesey
- Centre for Kidney Disease Research, Translational Research Institute, School of Medicine, University of Queensland, Brisbane, Queensland, Australia.,Department of Renal Medicine, University of Queensland at Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | - David W Johnson
- Centre for Kidney Disease Research, Translational Research Institute, School of Medicine, University of Queensland, Brisbane, Queensland, Australia.,Department of Renal Medicine, University of Queensland at Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | - Ross Francis
- Department of Renal Medicine, University of Queensland at Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | - Luis Vitetta
- Sydney Medical School - Medical Sciences, Medlab, Sydney, New South Wales, Australia.,Medlab Clinical Ltd., Medlab, Sydney, New South Wales, Australia
| | - Glenda C Gobe
- Centre for Kidney Disease Research, Translational Research Institute, School of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - Christudas Morais
- Centre for Kidney Disease Research, Translational Research Institute, School of Medicine, University of Queensland, Brisbane, Queensland, Australia
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31
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Karbowska M, Kaminski T, Pawlak D. Methods of reducing the level of indoxyl sulfate – one of the most potent protein-bound uremic toxins. TOXIN REV 2016. [DOI: 10.1080/15569543.2016.1222442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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32
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Vanholder RC, Eloot S, Glorieux GLRL. Future Avenues to Decrease Uremic Toxin Concentration. Am J Kidney Dis 2015; 67:664-76. [PMID: 26500179 DOI: 10.1053/j.ajkd.2015.08.029] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 08/19/2015] [Indexed: 01/13/2023]
Abstract
In this article, we review approaches for decreasing uremic solute concentrations in chronic kidney disease and in particular, in end-stage renal disease (ESRD). The rationale to do so is the straightforward relation between concentration and biological (toxic) effect for most toxins. The first section is devoted to extracorporeal strategies (kidney replacement therapy). In the context of high-flux hemodialysis and hemodiafiltration, we discuss increasing dialyzer blood and dialysate flows, frequent and/or extended dialysis, adsorption, bioartificial kidney, and changing physical conditions within the dialyzer (especially for protein-bound toxins). The next section focuses on the intestinal generation of uremic toxins, which in return is stimulated by uremic conditions. Therapeutic options are probiotics, prebiotics, synbiotics, and intestinal sorbents. Current data are conflicting, and these issues need further study before useful therapeutic concepts are developed. The following section is devoted to preservation of (residual) kidney function. Although many therapeutic options may overlap with therapies provided before ESRD, we focus on specific aspects of ESRD treatment, such as the risks of too-strict blood pressure and glycemic regulation and hemodynamic changes during dialysis. Finally, some recommendations are given on how research might be organized with regard to uremic toxins and their effects, removal, and impact on outcomes of uremic patients.
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Affiliation(s)
| | - Sunny Eloot
- Nephrology Department, University Hospital, Gent, Belgium
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Exploring Protein Binding of Uremic Toxins in Patients with Different Stages of Chronic Kidney Disease and during Hemodialysis. Toxins (Basel) 2015; 7:3933-46. [PMID: 26426048 PMCID: PMC4626712 DOI: 10.3390/toxins7103933] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/16/2015] [Accepted: 09/22/2015] [Indexed: 12/12/2022] Open
Abstract
As protein binding of uremic toxins is not well understood, neither in chronic kidney disease (CKD) progression, nor during a hemodialysis (HD) session, we studied protein binding in two cross-sectional studies. Ninety-five CKD 2 to 5 patients and ten stable hemodialysis patients were included. Blood samples were taken either during the routine ambulatory visit (CKD patients) or from blood inlet and outlet line during dialysis (HD patients). Total (CT) and free concentrations were determined of p-cresylglucuronide (pCG), hippuric acid (HA), indole-3-acetic acid (IAA), indoxyl sulfate (IS) and p-cresylsulfate (pCS), and their percentage protein binding (%PB) was calculated. In CKD patients, %PB/CT resulted in a positive correlation (all p < 0.001) with renal function for all five uremic toxins. In HD patients, %PB was increased after 120 min of dialysis for HA and at the dialysis end for the stronger (IAA) and the highly-bound (IS and pCS) solutes. During one passage through the dialyzer at 120 min, %PB was increased for HA (borderline), IAA, IS and pCS. These findings explain why protein-bound solutes are difficult to remove by dialysis: a combination of the fact that (i) only the free fraction can pass the filter and (ii) the equilibrium, as it was pre-dialysis, cannot be restored during the dialysis session, as it is continuously disturbed.
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Yu S, Xu X, Yigit C, van der Giet M, Zidek W, Jankowski J, Dzubiella J, Ballauff M. Interaction of human serum albumin with short polyelectrolytes: a study by calorimetry and computer simulations. SOFT MATTER 2015; 11:4630-4639. [PMID: 25959568 DOI: 10.1039/c5sm00687b] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present a comprehensive study of the interaction of human serum albumin (HSA) with poly(acrylic acid) (PAA; number average degree of polymerization: 25) in aqueous solution. The interaction of HSA with PAA is studied in dilute solution as a function of the concentration of added salt (20-100 mM) and temperature (25-37 °C). Isothermal titration calorimetry (ITC) is used to analyze the interaction and to determine the binding constant and related thermodynamic data. It is found that only one PAA chain is bound per HSA molecule. The free energy of binding ΔGb increases with temperature significantly. ΔGb decreases with increasing salt concentration and is dominated by entropic contributions due to the release of bound counterions. Coarse-grained Langevin computer simulations treating the counterions in an explicit manner are used to study the process of binding in detail. These simulations demonstrate that the PAA chains are bound in the Sudlow II site of HSA. Moreover, ΔGb is calculated from the simulations and found to be in very good agreement with the measured data. The simulations demonstrate clearly that the driving force of binding is the release of counterions in full agreement with the ITC-data.
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Affiliation(s)
- Shun Yu
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109 Berlin, Germany.
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Ascenzi P, Leboffe L, di Masi A, Trezza V, Fanali G, Gioia M, Coletta M, Fasano M. Ligand binding to the FA3-FA4 cleft inhibits the esterase-like activity of human serum albumin. PLoS One 2015; 10:e0120603. [PMID: 25790235 PMCID: PMC4366387 DOI: 10.1371/journal.pone.0120603] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 01/24/2015] [Indexed: 12/19/2022] Open
Abstract
The hydrolysis of 4-nitrophenyl esters of hexanoate (NphOHe) and decanoate (NphODe) by human serum albumin (HSA) at Tyr411, located at the FA3-FA4 site, has been investigated between pH 5.8 and 9.5, at 22.0°C. Values of Ks, k+2, and k+2/Ks obtained at [HSA] ≥ 5×[NphOXx] and [NphOXx] ≥ 5×[HSA] (Xx is NphOHe or NphODe) match very well each other; moreover, the deacylation step turns out to be the rate limiting step in catalysis (i.e., k+3 << k+2). The pH dependence of the kinetic parameters for the hydrolysis of NphOHe and NphODe can be described by the acidic pKa-shift of a single amino acid residue, which varies from 8.9 in the free HSA to 7.6 and 7.0 in the HSA:NphOHe and HSA:NphODe complex, respectively; the pK>a-shift appears to be correlated to the length of the fatty acid tail of the substrate. The inhibition of the HSA-Tyr411-catalyzed hydrolysis of NphOHe, NphODe, and 4-nitrophenyl myristate (NphOMy) by five inhibitors (i.e., diazepam, diflunisal, ibuprofen, 3-indoxyl-sulfate, and propofol) has been investigated at pH 7.5 and 22.0°C, resulting competitive. The affinity of diazepam, diflunisal, ibuprofen, 3-indoxyl-sulfate, and propofol for HSA reflects the selectivity of the FA3-FA4 cleft. Under conditions where Tyr411 is not acylated, the molar fraction of diazepam, diflunisal, ibuprofen, and 3-indoxyl-sulfate bound to HSA is higher than 0.9 whereas the molar fraction of propofol bound to HSA is ca. 0.5.
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Affiliation(s)
- Paolo Ascenzi
- Interdepartmental Laboratory of Electron Microscopy, Roma Tre University, Via della Vasca Navale 79, I-00146 Roma, Italy
| | - Loris Leboffe
- Department of Sciences, Roma Tre University, Viale Guglielmo Marconi 446, I-00146 Roma, Italy
| | - Alessandra di Masi
- Department of Sciences, Roma Tre University, Viale Guglielmo Marconi 446, I-00146 Roma, Italy
| | - Viviana Trezza
- Department of Sciences, Roma Tre University, Viale Guglielmo Marconi 446, I-00146 Roma, Italy
| | - Gabriella Fanali
- Biomedical Research Division, Department of Theoretical and Applied Sciences, University of Insubria, Via Alberto da Giussano 12, I-21052 Busto Arsizio (VA), Italy
| | - Magda Gioia
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, Via Montpellier 1, I-00133 Roma, Italy
- Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, Via Celso Ulpiani 27, I-70126 Bari, Italy
| | - Massimo Coletta
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, Via Montpellier 1, I-00133 Roma, Italy
- Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, Via Celso Ulpiani 27, I-70126 Bari, Italy
| | - Mauro Fasano
- Biomedical Research Division, Department of Theoretical and Applied Sciences, University of Insubria, Via Alberto da Giussano 12, I-21052 Busto Arsizio (VA), Italy
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Lekawanvijit S. Role of Gut-Derived Protein-Bound Uremic Toxins in Cardiorenal Syndrome and Potential Treatment Modalities. Circ J 2015; 79:2088-97. [DOI: 10.1253/circj.cj-15-0749] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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