scholarly journals Gut Microbiota and Their Derived Metabolites, a Search for Potential Targets to Limit Accumulation of Protein-Bound Uremic Toxins in Chronic Kidney Disease

Toxins ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 809
Author(s):  
Mieke Steenbeke ◽  
Sophie Valkenburg ◽  
Tessa Gryp ◽  
Wim Van Biesen ◽  
Joris R. Delanghe ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Plasma Levels ◽  
Plasma Concentrations ◽  
Intestinal Barrier ◽  
Uremic Toxins ◽  
Intestinal Barrier Function ◽  
Post Translational Modifications ◽  
Gut Dysbiosis ◽  
Cardiovascular Morbidity And Mortality

Chronic kidney disease (CKD) is characterized by gut dysbiosis with a decrease in short-chain fatty acid (SCFA)-producing bacteria. Levels of protein-bound uremic toxins (PBUTs) and post-translational modifications (PTMs) of albumin increase with CKD, both risk factors for cardiovascular morbidity and mortality. The relationship between fecal metabolites and plasma concentrations of PBUTs in different stages of CKD (n = 103) was explored. Estimated GFR tends to correlate with fecal butyric acid (BA) concentrations (rs = 0.212; p = 032), which, in its turn, correlates with the abundance of SCFA-producing bacteria. Specific SCFAs correlate with concentrations of PBUT precursors in feces. Fecal levels of p-cresol correlate with its derived plasma UTs (p-cresyl sulfate: rs = 0.342, p < 0.001; p-cresyl glucuronide: rs = 0.268, p = 0.006), whereas an association was found between fecal and plasma levels of indole acetic acid (rs = 0.306; p = 0.002). Finally, the albumin symmetry factor correlates positively with eGFR (rs = 0.274; p = 0.005). The decreased abundance of SCFA-producing gut bacteria in parallel with the fecal concentration of BA and indole could compromise the intestinal barrier function in CKD. It is currently not known if this contributes to increased plasma levels of PBUTs, potentially playing a role in the PTMs of albumin. Further evaluation of SCFA-producing bacteria and SCFAs as potential targets to restore both gut dysbiosis and uremia in needed.

MO460ASSOCIATION BETWEEN CARBAMYLATED ALBUMIN, GUT MICROBIOTA AND THEIR DERIVED METABOLITES IN CHRONIC KIDNEY DISEASE

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Mieke Steenbeke ◽  
Sophie Valkenburg ◽  
Wim Van Biesen ◽  
Joris Delanghe ◽  
Marijn Speeckaert ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Gut Microbiota ◽  
Plasma Levels ◽  
Pearson Correlation ◽  
Bacterial Species ◽  
Study Cohort ◽  
Gut Dysbiosis ◽  
Symmetry Factor ◽  
Cardiovascular Morbidity And Mortality

Abstract Background and Aims Chronic kidney disease (CKD) is characterized by gut dysbiosis. We recently demonstrated a decrease of short-chain fatty acid (SCFA) producing bacterial species with the progression of CKD. Besides, levels of protein-bound uremic toxins (PBUTs) and post-translational modifications of protein are increased in CKD, both are risk factors for accelerated cardiovascular morbidity and mortality. The link between the gut-kidney axis and protein carbamylation is unclear. The aim of the study was to explore the relation between carbamylated albumin, estimated by the albumin symmetry factor, and plasma levels of PBUTs, fecal levels of SCFAs (ongoing), and the abundance of related gut microbiota in different stages of CKD (1-5). Method The study cohort includes 103 non-dialyzed CKD patients (stages 1-5). Serum proteins were detected by capillary electrophoresis and UV absorbance at 214 nm with the symmetry factor as a marker of albumin carbamylation [the lower the symmetry factor, the more carbamylated albumin]. The quantification of PBUTs and SCFAs in plasma and fecal samples, respectively, using validated UPLC methods. Results The Pearson correlation coefficient (r) shows a positive correlation between the albumin symmetry factor and the estimated glomerular filtration rate (eGFR) (r=0.3025; p=0.0019). The albumin symmetry factor correlates positively with the abundance of Butyricicoccus spp. (r= 0.3211; p=0.0009), Faecalibacterium prausnitzii (r=0.2765; p=0.0047) and Roseburia spp. (r=0.2527; p=0.0100) and negatively with the PBUTs, p-cresyl sulfate (pCS) (r=-0.2819; p=0.0039), p-cresyl glucuronide (pCG) (r=-0.2819; p=0.0039) and indoxyl sulfate (IxS) (r=-0.2650; p=0.0068). Conclusion The decreased abundance of SCFA producing gut bacteria with the progression of CKD can evoke unfavorable conditions in the gut. This can contribute to increased plasma levels of PBUTs potentially (indirectly) playing a role in albumin carbamylation. It will be further explored whether fecal levels of SCFAs are affected in parallel and could be potential targets to restore gut dysbiosis and uremia.

scholarly journals The Role of Gut Dysbiosis in the Bone–Vascular Axis in Chronic Kidney Disease

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 285 ◽  
Author(s):  
Pieter Evenepoel ◽  
Sander Dejongh ◽  
Kristin Verbeke ◽  
Bjorn Meijers
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Intestinal Barrier ◽  
Intestinal Barrier Function ◽  
Mineral Density ◽  
Bone Mineral Density Loss ◽  
Gut Dysbiosis ◽  
Increased Risk ◽  
Fermentation Pattern

Patients with chronic kidney disease (CKD) are at increased risk of bone mineral density loss and vascular calcification. Bone demineralization and vascular mineralization often concur in CKD, similar to what observed in the general population. This contradictory association is commonly referred to as the ‘calcification paradox’ or the bone–vascular axis. Mounting evidence indicates that CKD-associated gut dysbiosis may be involved in the pathogenesis of the bone–vascular axis. A disrupted intestinal barrier function, a metabolic shift from a predominant saccharolytic to a proteolytic fermentation pattern, and a decreased generation of vitamin K may, alone or in concert, drive a vascular and skeletal pathobiology in CKD patients. A better understanding of the role of gut dysbiosis in the bone–vascular axis may open avenues for novel therapeutics, including nutriceuticals.

scholarly journals Chronic Kidney Disease, Gut Dysbiosis, and Constipation: A Burdensome Triplet

2020 ◽  
Vol 8 (12) ◽  
pp. 1862
Author(s):  
Ryota Ikee ◽  
Naomi Sasaki ◽  
Takuji Yasuda ◽  
Sawako Fukazawa
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Inflammatory Responses ◽  
Bacterial Species ◽  
Short Chain Fatty Acids ◽  
Uremic Toxins ◽  
Fermentation Products ◽  
Bacterial Fermentation ◽  
Gut Dysbiosis ◽  
Multiple Drugs

Gut dysbiosis has been implicated in the progression of chronic kidney disease (CKD). Alterations in the gut environment induced by uremic toxins, the dietary restriction of fiber-rich foods, and multiple drugs may be involved in CKD-related gut dysbiosis. CKD-related gut dysbiosis is considered to be characterized by the expansion of bacterial species producing precursors of harmful uremic toxins, such as indoxyl sulfate and p-cresyl sulfate, and the contraction of species generating beneficial short-chain fatty acids, such as butyrate. Gut-derived uremic toxins cause oxidative stress and pro-inflammatory responses, whereas butyrate exerts anti-inflammatory effects and contributes to gut epithelial integrity. Gut dysbiosis is associated with the disruption of the gut epithelial barrier, which leads to the translocation of endotoxins. Research on CKD-related gut dysbiosis has mainly focused on chronic inflammation and consequent cardiovascular and renal damage. The pathogenic relationship between CKD-related gut dysbiosis and constipation has not yet been investigated in detail. Constipation is highly prevalent in CKD and affects the quality of life of these patients. Under the pathophysiological state of gut dysbiosis, altered bacterial fermentation products may play a prominent role in intestinal dysmotility. In this review, we outline the factors contributing to constipation, such as the gut microbiota and bacterial fermentation; introduce recent findings on the pathogenic link between CKD-related gut dysbiosis and constipation; and discuss potential interventions. This pathogenic link needs to be elucidated in more detail and may contribute to the development of novel treatment options not only for constipation, but also cardiovascular disease in CKD.

scholarly journals Gut-Derived Metabolites and Their Role in Immune Dysfunction in Chronic Kidney Disease

Toxins ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 245 ◽  
Author(s):  
Griet Glorieux ◽  
Tessa Gryp ◽  
Alessandra Perna
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Intestinal Barrier ◽  
Uremic Toxins ◽  
Bacterial Metabolism ◽  
Immunomodulatory Effects ◽  
Inflammatory Status ◽  
Current Review ◽  
And Function ◽  
Circulating Levels

Several of the uremic toxins, which are difficult to remove by dialysis, originate from the gut bacterial metabolism. This opens opportunities for novel targets trying to decrease circulating levels of these toxins and their pathophysiological effects. The current review focuses on immunomodulatory effects of these toxins both at their side of origin and in the circulation. In the gut end products of the bacterial metabolism such as p-cresol, trimethylamine and H2S affect the intestinal barrier structure and function while in the circulation the related uremic toxins stimulate cells of the immune system. Both conditions contribute to the pro-inflammatory status of patients with chronic kidney disease (CKD). Generation and/or absorption of these toxin precursors could be targeted to decrease plasma levels of their respective uremic toxins and to reduce micro-inflammation in CKD.

scholarly journals Pharmacokinetics and pharmacodynamics of TTI-101, a STAT3 inhibitor that blocks muscle proteolysis in rats with chronic kidney disease

2020 ◽  
Vol 319 (1) ◽  
pp. F84-F92 ◽  
Author(s):  
Liping Zhang ◽  
Ying Wang ◽  
Yanlan Dong ◽  
Zihong Chen ◽  
Thomas K. Eckols ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Plasma Levels ◽  
Muscle Protein ◽  
Plasma Concentrations ◽  
Maximum Plasma ◽  
Pharmacokinetics And Pharmacodynamics ◽  
Molecule Inhibitor ◽  
Enhancer Binding Protein ◽  
Maximal Plasma

Loss of muscle proteins increases the morbidity and mortality of patients with chronic kidney disease (CKD), and there are no reliable preventive treatments. We uncovered a STAT3/CCAAT-enhancer-binding protein-δ to myostatin signaling pathway that activates muscle protein degradation in mice with CKD or cancer; we also identified a small-molecule inhibitor of STAT3 (TTI-101) that blocks this pathway. To evaluate TTI-101 as a treatment for CKD-induced cachexia, we measured TTI-101 pharmacokinetics and pharmacodynamics in control and CKD rats that were orally administered TTI-101or its diluent. The following two groups of gavage-fed rats were studied: sham-operated control rats and CKD rats. Plasma was collected serially (0, 0.25, 0.5, 1, 2, 4, 8, and 24 h) following TTI-101 administration (at oral doses of 0, 10, 30, or 100 mg/kg). Plasma levels of TTI-101 were measured by LC-MS/MS, and pharmacokinetic results were analyzed with the PKSolver program. Plasma TTI-101 levels increased linearly with doses; the maximum plasma concentrations and time to maximal plasma levels (~1 h) were similar in sham-operated control rats and CKD rats. Notably, gavage treatment of TTI-101 for 3 days produced TTI-101 muscle levels in sham control rats and CKD rats that were not significantly different. CKD rats that received TTI-101 for 7 days had suppression of activated STAT3 and improved muscle grip strength; there also was a trend for increasing body and muscle weights. TTI-101 was tolerated at doses of 100 mg·kg−1·day−1 for 7 days. These results with TTI-101 in rats warrant its development as a treatment for cachexia in humans.

scholarly journals Effects of prebiotic oligofructose-enriched inulin on gut-derived uremic toxins and disease progression in rats with adenine-induced chronic kidney disease

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258145
Author(s):  
Ebru Melekoglu ◽  
M. Alper Cetinkaya ◽  
S. Evrim Kepekci-Tekkeli ◽  
Oguz Kul ◽  
Gulhan Samur
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Disease Progression ◽  
Reactive Oxygen Species Generation ◽  
Uremic Toxins ◽  
Intestinal Barrier Function ◽  
Control Group ◽  
Standard Diet ◽  
Serum Urea ◽  
Sprague Dawley

Recent studies suggest that dysbiosis in chronic kidney disease (CKD) increases gut-derived uremic toxins (GDUT) generation, leads to systemic inflammation, reactive oxygen species generation, and poor prognosis. This study aimed to investigate the effect of oligofructose-enriched inulin supplementation on GDUT levels, inflammatory and antioxidant parameters, renal damage, and intestinal barrier function in adenine-induced CKD rats. Male Sprague-Dawley rats were divided into control group (CTL, n = 12) fed with standard diet; and CKD group (n = 16) given adenine (200 mg/kg/day) by oral gavage for 3-weeks to induce CKD. At the 4th week, CKD rats were subdivided into prebiotic supplementation (5g/kg/day) for four consecutive weeks (CKD-Pre, n = 8). Also, the control group was subdivided into two subgroups; prebiotic supplemented (CTL-Pre, n = 6) and non-supplemented group (CTL, n = 6). Results showed that prebiotic oligofructose-enriched inulin supplementation did not significantly reduce serum indoxyl sulfate (IS) but did significantly reduce serum p-Cresyl sulfate (PCS) (p = 0.002) in CKD rats. Prebiotic supplementation also reduced serum urea (p = 0.008) and interleukin (IL)-6 levels (p = 0.001), ameliorated renal injury, and enhanced antioxidant enzyme activity of glutathione peroxidase (GPx) (p = 0.002) and superoxide dismutase (SOD) (p = 0.001) in renal tissues of CKD rats. No significant changes were observed in colonic epithelial tight junction proteins claudin-1 and occludin in the CKD-Pre group. In adenine-induced CKD rats, oligofructose-enriched inulin supplementation resulted in a reduction in serum urea and PCS levels, enhancement of the antioxidant activity in the renal tissues, and retardation of the disease progression.

scholarly journals Isolation and Quantification of Uremic Toxin Precursor-Generating Gut Bacteria in Chronic Kidney Disease Patients

2020 ◽  
Vol 21 (6) ◽  
pp. 1986 ◽  
Author(s):  
Tessa Gryp ◽  
Geert R.B. Huys ◽  
Marie Joossens ◽  
Wim Van Biesen ◽  
Griet Glorieux ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Kidney Function ◽  
Bacterial Species ◽  
Uremic Toxins ◽  
Bacterial Number ◽  
Uremic Toxin ◽  
Microbial Composition ◽  
Indolic Compounds ◽  
Cardiovascular Morbidity And Mortality

In chronic kidney disease (CKD), impaired kidney function results in accumulation of uremic toxins, which exert deleterious biological effects and contribute to inflammation and cardiovascular morbidity and mortality. Protein-bound uremic toxins (PBUTs), such as p-cresyl sulfate, indoxyl sulfate and indole-3-acetic acid, originate from phenolic and indolic compounds, which are end products of gut bacterial metabolization of aromatic amino acids (AAA). This study investigates gut microbial composition at different CKD stages by isolating, identifying and quantifying PBUT precursor-generating bacteria. Fecal DNA extracts from 14 controls and 138 CKD patients were used to quantify total bacterial number and 11 bacterial taxa with qPCR. Moreover, isolated bacteria from CKD 1 and CKD 5 fecal samples were cultured in broth medium supplemented with AAA under aerobic and anaerobic conditions, and classified as PBUT precursor-generators based on their generation capacity of phenolic and indolic compounds, measured with U(H)PLC. In total, 148 different fecal bacterial species were isolated, of which 92 were PBUT precursor-generators. These bacterial species can be a potential target for reducing PBUT plasma levels in CKD. qPCR indicated lower abundance of short chain fatty acid-generating bacteria, Bifidobacterium spp. and Streptococcus spp., and higher Enterobacteriaceae and E. coli with impaired kidney function, confirming an altered gut microbial composition in CKD.

scholarly journals The gut–kidney–heart axis in chronic kidney disease

2019 ◽  
Vol 106 (3) ◽  
pp. 195-206 ◽  
Author(s):  
K Sumida ◽  
CP Kovesdy
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Gut Microbiota ◽  
Therapeutic Potential ◽  
Intestinal Barrier ◽  
Systemic Circulation ◽  
Biological Properties ◽  
Intestinal Barrier Function ◽  
Multiple Organs ◽  
Health And Disease

The recent explosion of scientific interest in the gut microbiota has dramatically advanced our understanding of the complex pathophysiological interactions between the gut and multiple organs in health and disease. Emerging evidence has revealed that the gut microbiota is significantly altered in patients with chronic kidney disease (CKD), along with impaired intestinal barrier function. These alterations allow translocation of various gut-derived products into the systemic circulation, contributing to the development and progression of CKD and cardiovascular disease (CVD), partly mediated by chronic inflammation. Among potentially toxic gut-derived products identifiable in the systemic circulation, bacterial endotoxin and gut metabolites (e.g., p-cresyl sulfate and trimethylamine-N-oxide) have been extensively studied for their immunostimulatory and atherogenic properties. Recent studies have also suggested similar biological properties of bacterial DNA fragments circulating in the blood of patients with CKD, even in the absence of overt infections. Despite the accumulating evidence of the gut microbiota in CKD and its therapeutic potential for CVD, the precise mechanisms for multidirectional interactions between the gut, kidney, and heart remain poorly understood. This review aims to provide recent evidence on the associations between the gut microbiota, CKD, and CVD, and summarize current understanding of the potential pathophysiological mechanisms underlying the “gut–kidney–heart” axis in CKD.

scholarly journals Intestinal Barrier Function in Chronic Kidney Disease

Toxins ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 298 ◽  
Author(s):  
Björn Meijers ◽  
Ricard Farré ◽  
Sander Dejongh ◽  
Maria Vicario ◽  
Pieter Evenepoel
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Kidney Function ◽  
Intestinal Barrier ◽  
Multilayered Structure ◽  
Toxic Waste ◽  
Intestinal Barrier Function ◽  
Waste Products ◽  
Mucin Layer ◽  
Altered Physiology

The kidneys are key contributors to body homeostasis, by virtue of controlled excretion of excessive fluid, electrolytes, and toxic waste products. The syndrome of uremia equals the altered physiology due to irreversible loss of kidney function that is left uncorrected for, despite therapeutic intervention(s). The intestines and its microbial content are prime contributors to this syndrome. The intestinal barrier separates the self (or the so-called “milieu intérior”) from the environment. In the large intestine, the intestinal barrier keeps apart human physiology and the microbiota. The enterocytes and the extracellular mucin layer functions form a complex multilayered structure, facilitating complex bidirectional metabolic and immunological crosstalk. The current review focuses on the intestinal barrier in chronic kidney disease (CKD). Loss of kidney function results in structural and functional alterations of the intestinal barrier, contribution to the syndrome of uremia.

scholarly journals Gut-Derived Protein-Bound Uremic Toxins

Toxins ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 590 ◽  
Author(s):  
Amanda L. Graboski ◽  
Matthew R. Redinbo
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Gut Microbiota ◽  
Filtration Rate ◽  
Therapeutic Strategies ◽  
Uremic Toxins ◽  
Uremic Toxin ◽  
Risk Of Death ◽  
Gut Dysbiosis ◽  
Causes Of Mortality

Chronic kidney disease (CKD) afflicts more than 500 million people worldwide and is one of the fastest growing global causes of mortality. When glomerular filtration rate begins to fall, uremic toxins accumulate in the serum and significantly increase the risk of death from cardiovascular disease and other causes. Several of the most harmful uremic toxins are produced by the gut microbiota. Furthermore, many such toxins are protein-bound and are therefore recalcitrant to removal by dialysis. We review the derivation and pathological mechanisms of gut-derived, protein-bound uremic toxins (PBUTs). We further outline the emerging relationship between kidney disease and gut dysbiosis, including the bacterial taxa altered, the regulation of microbial uremic toxin-producing genes, and their downstream physiological and neurological consequences. Finally, we discuss gut-targeted therapeutic strategies employed to reduce PBUTs. We conclude that targeting the gut microbiota is a promising approach for the treatment of CKD by blocking the serum accumulation of PBUTs that cannot be eliminated by dialysis.

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