Search Results (31)

Background: Diabetes mellitus (DM) and chronic kidney disease (CKD) are major contributors to global morbidity and mortality, with disease progression being closely linked to persistent inflammation, oxidative damage, and apoptotic pathways. Icariin (ICA), a bioactive flavonoid compound isolated from Epimedium brevicornum Maxim, has attracted considerable interest because of its diverse pharmacological properties. We evaluated the effect of ICA on streptozotocin (STZ)-induced diabetic rats with or without adenine-induced CKD. This combined model reproduces several key structural and functional characteristics observed in human diabetic kidney disease and advanced CKD. Methods: Male Wistar rats were allocated to five treatment groups and followed for 35 days. Group 1 served as the untreated control and received standard chow; Group 2 was administered streptozotocin (STZ); Group 3 received STZ together with icariin (ICA); Group 4 received a combination of adenine and STZ; and Group 5 was treated with adenine, STZ, and ICA. ICA was administered at a dose of 200 mg/kg by oral gavage. Biochemical, oxidative stress and inflammatory markers were assessed. Results: Rats treated with STZ, with or without adenine, exhibited significant hyperglycemia, elevated plasma levels of cystatin C and indoxyl sulphate, increased urinary levels of N-acetyl-β-D-glucosaminidase (NAG) and NAG/creatinine ratio, and reduced creatinine clearance. Additionally, there were significant decreases in renalase activity and urine osmolality, significant increases in interleukins IL-1β and IL-6 and TNF-alpha levels, and a decrease in IL-10 level. Oxidative stress biomarkers were also significantly impaired in both groups, along with significant renal histopathological changes. ICA significantly ameliorated these alterations in both experimental groups. Conclusions: These findings demonstrate that ICA exerts renoprotective and anti-inflammatory effects in a clinically relevant model of advanced diabetic CKD. Further studies are warranted to elucidate the underlying mechanisms and determine the translational relevance of these findings. Full article

Background: Dietary fibre has been increasingly recognised for its potential role in modulating inflammation, gut-derived uraemic toxins, nutritional status, and kidney-related outcomes in chronic kidney disease (CKD), particularly through mechanisms involving the gut–liver–kidney axis. While nutritional management in CKD has traditionally focused on protein intake, despite growing evidence supporting soluble and insoluble types, the role of dietary fibre remains insufficiently reflected in clinical guidelines. Objective: This systematic review evaluated the effects of dietary fibre intake on inflammatory markers, gut-derived uraemic toxins, nutritional status, kidney function, and mechanistic pathways relevant to gut–liver–kidney axis among CKD patients. Methods: PubMed, Scopus and Medline Complete were searched for observational and interventional human studies. Review articles and animal studies were excluded. A total of 45 met eligibility criteria. Risk-of-bias (RoB) was assessed using domain-based tools, and findings were synthesised narratively across predefined outcome domains. Results: Higher fibre intake was generally associated with reductions in interleukin-6 (IL-6) and selective improvements in inflammatory tone including Tumor Necrosis Factor alpha (TNF-α), while effects on C-reactive protein (CRP) varied. Several fermentable fibres were frequently linked with reduced gut-derived uraemic toxins, including indoxyl sulphate (IS), p-cresyl sulphate (pCS), and less consistently trimethylamine-N-oxide (TMAO). Nutritional markers such as albumin, BMI and overall diet quality were typically maintained or improved. Kidney function was stable across short-term interventions, with suggestions of slower decline in longer studies incorporating fibre-rich dietary patterns. Mechanistic studies frequently reported increased saccharolytic activity and favourable changes in fermentation profiles. Despite growing evidence, soluble fibre remains an underrepresented component in CKD dietary guidelines, warranting further high-quality interventional studies to confirm its therapeutic potential. Full article

Background: Patients with kidney failure requiring dialysis experience a high burden of vaccine-preventable diseases, and vaccine hypo-responsiveness is a key contributor. Uraemic toxins and gut dysbiosis are potential causes of hypo-responsiveness. Aim: This study aimed to determine whether uraemic toxin concentrations or gut dysbiosis are associated with vaccine response in haemodialysis patients. Methods: This was a single centre, observational cohort study of maintenance dialysis patients receiving a conventional 2-dose primary COVID-19 vaccination course. Demographic, clinical and vaccination data were collected from the eMR. Vaccine response (Elecsys Anti-SARS-CoV-2 immunoassay), serum uraemic toxin concentrations (indoxyl sulphate, p-cresyl sulphate, and trimethylamine N-oxide by liquid chromatography), and stool microbiome (16S rRNA gene sequencing) were measured 8 weeks after the second dose of vaccine. Results: Forty participants (43% female, mean age 66 years; 59% Caucasian) were included, 70% of whom were classified as a vaccine responder. Antibiotic exposure, prednisolone use and lymphopenia were significantly associated with hypo-responsiveness. Microbiome profiling identified differences in beta diversity between responders and non-responders, positively correlated with short-chain fatty acid producers (Parabacteriodes) and negatively with pathobionts (Escherichia/Shigella). Differential abundance analysis identified lower levels of Tyzzerella, Gemmiger, and Hungatella and higher levels of Turicibacter in vaccine responders. Total uraemic toxin burden and individual toxin concentrations did not differ between responders and hypo-responders (all p > 0.05). Stratification by low versus high/very high toxin burden groupings was not associated with response (p > 0.99). Conclusions: Differences in gut microbial composition were observed between vaccine responder groups, while uraemic toxin concentrations were not associated with vaccine responsiveness. These findings suggest gut microbiota composition may contribute to vaccine hypo-responsiveness in individuals receiving dialysis and warrant further investigation in larger mechanistic studies. Full article

Background and Objectives: In many neurodegenerative diseases, the pathological changes occurring in the central nervous system may be reflected in the periphery. The aim of this study was to examine the possible relationship between the retina, choroid, and nerve fibre layer thicknesses measured on optic coherence tomography (OCT) and the serum microbiota metabolite levels of trimethyl amine-N-oxide (TMAO), S-equol, Indoxyl sulphate (IS), and Maresin 1 (MaR1). Materials and Methods: This study included a total of 60 subjects, comprising 30 patients diagnosed with schizophrenia and a control group of 30 healthy individuals. A sociodemographic form was given to all the subjects and the Positive and Negative Syndrome Scale (PANSS) to the schizophrenia patients. The eye fundus was evaluated with OCT. A 5 mL blood sample was taken from the arm of each subject, and the microbiota metabolite levels of TMAO, S-equol, IS, and MaR1 were examined. Results: The retina nerve fibre layer (RNFL) analysis results showed that the RNFL superior (p = 0.016), inferior (p = 0.002), central choroid (p = 0.033), nasal choroid (p = 0.004), temporal choroid (p = 0.038), and TMAO (p = 0.001) values were significantly lower in the schizophrenia patients than in the control group. In the patient group, a significant negative correlation was determined between the RNFL temporal measurements and IS, as well as a significant positive correlation between the central choroid measurement and the nasal choroid and temporal choroid measurements and between the nasal choroid and temporal choroid measurements. A statistically significant positive correlation was seen between S-equol and TMAO. A significant negative correlation was seen between the MaR1 level and age and disease duration. Conclusions: The study results showed that fundus changes are associated with serum microbiota metabolite levels in schizophrenia patients. Therefore, these parameters may be considered potential exploratory biomarkers; however, their clinical applicability requires validation in larger longitudinal studies. Full article

Chronic kidney disease (CKD) accelerates vascular dysfunction and cardiovascular disease, partly through the accumulation of the uraemic toxin indoxyl sulphate (IS). Thrombospondin-1 (TSP1) and its receptor CD47 have been implicated in vascular pathology, but their role in CKD-associated vascular remodelling is unknown. We investigated the contribution of TSP1–CD47 signalling to vascular smooth muscle cell (VSMC) dysfunction in CKD. Human aortic VSMCs (hVSMCs) were exposed to IS, TSP1, or plasma from patients with CKD. CKD was induced in wild-type (WT) and CD47-deficient (CD47KO) mice using 5/6 nephrectomy. Vascular changes were assessed by histology, immunohistochemistry, and molecular analyses. IS, TSP1, and CKD plasma increased TSP1 expression in hVSMCs, reduced proliferation, elevated β-galactosidase activity, and activated phosphorylated ERK1/2 and cytoplasmic aryl hydrocarbon receptor. These effects were attenuated by CD47 blockade. CKD plasma further enhanced IS- and TSP1-induced senescence. In vivo, 5/6 nephrectomy induced aortic wall thickening in WT but not in CD47KO mice. Aortic pERK1/2 was reduced in CD47KO mice despite persistent TSP1 upregulation. IS and TSP1 promote VSMC senescence through CD47-dependent ERK1/2 and AhR signalling. CD47 deletion protects against CKD-induced vascular remodelling, suggesting that CD47 blockade may represent a novel therapeutic strategy to mitigate vascular complications in CKD. Full article

Protein-bound uremic toxins (PBUT), particularly indoxyl sulphate (IS) and p-cresyl sulphate (pCS), are poorly removed by conventional haemodialysis because of their strong albumin binding. These toxins are associated with cardiovascular morbidity and mortality in haemodialysis patients. Displacer molecules such as ibuprofen enhance PBUT clearance by competing for albumin-binding sites, but the optimal dose and route of administration remain unclear. The aim of this study was to evaluate the effect of different ibuprofen doses, infusion durations, and routes of administration on the removal of IS and pCS during on-line hemodiafiltration (OL-HDF). In this prospective, single-centre, crossover study, 21 chronic haemodialysis patients receiving intradialytic analgesia underwent nine OL-HDF sessions. Ibuprofen was administered at two doses (400 or 800 mg) either in the arterial pre-filter line (infusion over 1 h, 2 h, or 3 h) or in the venous post-filter line (30 min). Reduction ratios (RR) of total IS and pCS were determined by LC-MS and corrected for haemoconcentration. Statistical analysis included repeated-measures ANOVA with post-hoc testing. Baseline RR for IS and pCS were 53.7 ± 9.9% and 47.1 ± 10.9%, respectively. The highest RR was achieved with 800 mg ibuprofen infused via the arterial line over 2 h (IS: 60.8 ± 8.6%; pCS: 57.8 ± 9.7%). All arterial-line 800 mg regimens and the 3-h 400 mg infusion significantly improved pCS clearance versus baseline; IS clearance improved significantly only with arterial-line 800 mg regimens and with the 400 mg 3-h infusion. Infusion rate (1–3 h) had no significant effect on RR within the same dose group. Pain scores decreased significantly after dialysis regardless of ibuprofen regimen. Arterial-line administration of ibuprofen enhances total IS and pCS removal during OL-HDF, with higher doses yielding greater clearance. Prolonged low-dose infusion appears similarly effective for pCS and may reduce systemic exposure, potentially lowering toxicity risk. These findings support the arterial line as the preferred route for displacer administration in clinical practice. Full article

Nephrotoxin-mediated kidney injury is an important clinical problem, as it can lead to acute kidney injury and chronic kidney disease. Both entities are associated with significant morbidity, increased hospitalisation, healthcare utilisation, and cardiovascular mortality. With the loss of kidney function, there is an accumulation of uraemic toxins, of which the protein-bound toxins—indoxyl sulphate and p-cresyl sulphate—can further inflict damage to the kidneys and the cardiovascular system, culminating in a vicious cycle. Therefore, it is imperative that clinicians have a firm understanding of the common causes and mechanisms of toxin-mediated kidney injury, as well as their clinical presentations and histopathologic features, in order to reduce the prevalence of this pernicious condition. Full article

Background: Obesity is a risk factor for several non-communicable diseases and premature death. The Western-type diet, rich in calories and diverse in tastes, smells, and textures, promotes the onset and progression of obesity. We compared the effects of two Western-style palatable obesogenic diets—the cafeteria (CAF) diet, which allows for self-selection of calorie-dense food items consumed by humans, and the fast-food diet (FFD)—composed of a fixed combination of cheeseburgers and fries—on the manifestation of obesity-related complications. Methods: 3-month-old female rats consumed either the control (CTRL), FFD, or CAF diet for 12 months. Body weight was monitored weekly. At the end of the experiment, rats underwent metabolic and behavioral testing. Cardiometabolic markers and those characterizing glycoxidative and carbonyl stress, inflammatory status, and tryptophan metabolism were determined. Results: The CAF rats gain most weight (CTRL: +111 ± 40 g; FFD: +211 ± 77 g; CAF: 316 ± 87 g). CAF feeding produced a classical metabolic syndrome–like profile with severe obesity, insulin resistance, dyslipidemia, and liver steatosis, whereas the FFD model led to moderate obesity with preserved insulin sensitivity but elevated blood pressure and hepatic cholesterol accumulation. Thus, the CAF group developed a severe metabolic syndrome-like pathology assessed as continuous metabolic syndrome z-core (CTRL: −2.3 ± 1.0; FFD: −0.4 ± 1.9; CAF: 3.0 ± 2.4). Despite these differences, both diets promoted neuroinflammation and social deficits, likely mediated through gut microbiota–derived metabolites such as 5-HIAA and indoxyl sulfate. Conclusions: In female rats, self-selected CAF diet drives more severe and distinct pattern of metabolic syndrome-like pathology than a fixed FFD. Full article

Furosemide appears to contribute to the accumulation of protein-bound uremic toxins (PBUTs) and to induce adverse drug reactions. We investigated the extent to which the association between the furosemide dose and serum PBUT concentrations mediates the relationship between the furosemide dose and the symptom burden in patients with chronic kidney disease (CKD). This cross-sectional analysis included patients with CKD stages 2 to 5 from the CKD-REIN cohort and with data on the baseline serum concentrations of the free fractions of indoxyl sulphate (IS), kynurenine (KYN), p-cresyl sulphate (PCS), and indole-3-acetic acid (IAA), as measured by liquid chromatography–tandem mass spectrometry. The symptom burden was also assessed with a modified (8-item) symptom subscale from the Kidney Disease Quality of Life-36 (e.g., muscle soreness, cramps, itchy skin, dry skin, dizziness, appetite, numbness, and nausea). We used beta regressions to model the association between the furosemide dose and the symptom burden and used structural equation models to quantify the mediating effect of PBUT on this association. Among the 2053 included patients (males: 66%, median age: 68; mean estimated glomerular filtration rate: 35 mL/min/1.73 m²), those prescribed high-dose furosemide (>120 mg/day) had higher symptom burden than those not prescribed furosemide (i.e., a 5.67-point lower symptom score, 95%CI 1.41–9.93). The sum of PBUTs explained 3.78% (95%CI 0.10–18.01%) of this association. Similar results were observed for IS, KYN, and IAA, considered separately, but not for PCS, whose estimated mediation effect was nearly null. Although high-dose furosemide was associated with a greater symptom burden in patients with CKD, mediation by PBUT accumulation appeared to be minimal. Full article

Protein-bound uraemic toxins (PBUTs), such as indoxyl sulphate (IS) and p-cresyl sulphate (PCS), are poorly cleared by conventional haemodialysis (HD) or haemodiafiltration (HDF). Haemoadsorption combined with HD (HAHD) using the novel pHA130 cartridge may increase PBUT removal, and this trial aimed to compare its efficacy and safety with HDF in patients with end-stage renal disease (ESRD). In this single-centre, open-label trial, 30 maintenance HD patients were randomized (1:1:1) to HDF once every two weeks (HDF-q2w), HAHD once every two weeks (HAHD-q2w), or HAHD once weekly (HAHD-q1w) for 8 weeks, with the primary endpoint being the single-session reduction ratio (RR) of IS. The combined HAHD group (n = 20) demonstrated a significantly greater IS reduction than the HDF-q2w group (n = 10) (46.9% vs. 31.8%; p = 0.044) and superior PCS clearance (44.6% vs. 31.4%; p = 0.003). Both HAHD regimens significantly reduced predialysis IS levels at Week 8. Compared with HDF, weekly HAHD provided greater relief from pruritus and improved sleep quality, with comparable adverse events among groups. In conclusion, HAHD with the pHA130 cartridge is more effective than HDF for enhancing single-session PBUT removal and alleviating uraemic symptoms in patients with ESRD, with weekly application showing optimal symptomatic benefits. Full article

High levels of social stress are known to negatively impact pig welfare. The aim of this study was to evaluate the impact of social stress in growing–finishing pigs by measuring serum metabolome changes and saliva biomarkers. Seventy-two undocked pigs (thirty-six males and thirty-six females) were housed in single-sex pens of four, with the second dominant pig in each pen selected as the focal pig. A social challenge was conducted by mixing the focal pig with three new pigs in its home pen on two consecutive days on trial days 62–64. Saliva and blood samples were collected, and the pigs’ behaviour and body lesions were evaluated pre- and post-challenge. A total of 630 serum metabolites were analysed, 292 of which could be statistically compared using Biocrates WebIDQ v5 software. Salivary haptoglobin concentrations and the number of body lesions significantly increased after the challenge (p < 0.001), whereas the average daily weight gain decreased (p < 0.05). The serum showed decreases in essential amino acids (Thr, Met, and Phe), non-essential amino acids (Glu, Asn, Asp, Pro, and Tyr), betaine, ornithine, indoxyl sulphate, taurine, and some blood di- and triacylglycerols (q < 0.05), and increases in oleic, eicosanoic, eicosadienoic, and dihomo-gamma-linolenic acids; EPA; and DHA post-challenge (q < 0.05). Overall, the results suggest the potential of metabolomics as a tool providing a more holistic view of the impact of social stress. Full article

In this investigation, we outline the applications of a data mining technique known as Subgroup Discovery (SD) to the analysis of a sample size-limited metabolomics-based dataset. The SD technique utilized a supervised learning strategy, which lies midway between classificational and descriptive criteria, in which given the descriptive property of a dataset (i.e., the response target variable of interest), the primary objective was to discover subgroups with behaviours that are distinguishable from those of the complete set (albeit with a differential statistical distribution). These approaches have, for the first time, been successfully employed for the analysis of aromatic metabolite patterns within an NMR-based urinary dataset collected from a small cohort of patients with the lysosomal storage disorder Niemann–Pick class 1 (NPC1) disease (n = 12) and utilized to distinguish these from a larger number of heterozygous (parental) control participants. These subgroup discovery strategies discovered two different NPC1 disease-specific metabolically sequential rules which permitted the reliable identification of NPC1 patients; the first of these involved ‘normal’ (intermediate) urinary concentrations of xanthurenate, 4-aminobenzoate, hippurate and quinaldate, and disease-downregulated levels of nicotinate and trigonelline, whereas the second comprised ‘normal’ 4-aminobenzoate, indoxyl sulphate, hippurate, 3-methylhistidine and quinaldate concentrations, and again downregulated nicotinate and trigonelline levels. Correspondingly, a series of five subgroup rules were generated for the heterozygous carrier control group, and ‘biomarkers’ featured in these included low histidine, 1-methylnicotinamide and 4-aminobenzoate concentrations, together with ‘normal’ levels of hippurate, hypoxanthine, quinolinate and hypoxanthine. These significant disease group-specific rules were consistent with imbalances in the combined tryptophan–nicotinamide, tryptophan, kynurenine and tyrosine metabolic pathways, along with dysregulations in those featuring histidine, 3-methylhistidine and 4-hydroxybenzoate. In principle, the novel subgroup discovery approach employed here should also be readily applicable to solving metabolomics-type problems of this nature which feature rare disease classification groupings with only limited patient participant and sample sizes available. Full article

Atherosclerosis is initiated by the activation of endothelial cells that allows monocyte adhesion and transmigration through the vascular wall. The accumulation of uremic toxins such as indoxyl sulphate (IS) and p-cresol (PC) has been associated with atherosclerosis. Currently, miRNAs play a crucial role in the regulation of monocyte activation, adhesion, and trans-endothelial migration. The aim of the present study is to evaluate the effect of IS and PC on monocyte adhesion and migration processes in monocytes co-cultured with endothelial cells as well as to determine the underlying mechanisms. The incubation of HUVECs and THP-1 cells with both IS and PC toxins resulted in an increased migratory capacity of THP-1 cells. Furthermore, the exposure of THP-1 cells to both uremic toxins resulted in the upregulation of BMP-2 and miRNAs-126-3p, -146b-5p, and -223-3p, as well as the activation of nuclear factor kappa B (NF-κB) and a decrease in its inhibitor IĸB. Uremic toxins, such as IS and PC, enhance the migratory and adhesion capacity of THP-1 cells to the vascular endothelium. These toxins, particularly PC, contribute significantly to uremia-associated vascular disease by increasing in THP-1 cells the expression of BMP-2, NF-κB, and key miRNAs associated with the development of atherosclerotic vascular diseases. Full article

Autism spectrum disorder (ASD) is a complex developmental disorder in which communication and behavior are affected. A number of studies have investigated potential biomarkers, including uremic toxins. The aim of our study was to determine uremic toxins in the urine of children with ASD (143) and compare the results with healthy children (48). Uremic toxins were determined with a validated high-performance liquid chromatography coupled to mass spectrometry (LC-MS/MS) method. We observed higher levels of p-cresyl sulphate (pCS) and indoxyl sulphate (IS) in the ASD group compared to the controls. Moreover, the toxin levels of trimethylamine N-oxide (TMAO), symmetric dimethylarginine (SDMA), and asymmetric dimethylarginine (ADMA) were lower in ASD patients. Similarly, for pCS and IS in children classified, according to the intensity of their symptoms, into mild, moderate, and severe, elevated levels of these compounds were observed. For mild severity of the disorder, elevated levels of TMAO and comparable levels of SDMA and ADMA for ASD children as compared to the controls were observed in the urine. For moderate severity of ASD, significantly elevated levels of TMAO but reduced levels of SDMA and ADMA were observed in the urine of ASD children as compared to the controls. When the results obtained for severe ASD severity were considered, reduced levels of TMAO and comparable levels of SDMA and ADMA were observed in ASD children. Full article

Kidney transplantation (KTx) is the preferred form of renal replacement therapy in chronic kidney disease (CKD) patients, owing to increased quality of life and reduced mortality when compared to chronic dialysis. Risk of cardiovascular disease is reduced after KTx; however, it is still a leading cause of death in this patient population. Thus, we aimed to investigate whether functional properties of the vasculature differed two years post-KTx (postKTx) compared to baseline (time of KTx). Using the EndoPAT device in 27 CKD patients undergoing living-donor KTx, we found that vessel stiffness significantly improved while endothelial function worsened postKTx vs. baseline. Furthermore, baseline serum indoxyl sulphate (IS), but not p-cresyl sulphate, was independently negatively associated with reactive hyperemia index, a marker of endothelial function, and independently positively associated with P-selectin postKTx. Finally, to better understand the functional effects of IS in vessels, we incubated human resistance arteries with IS overnight and performed wire myography experiments ex vivo. IS-incubated arteries showed reduced bradykinin-mediated endothelium-dependent relaxation compared to controls via reduced nitric oxide (NO) contribution. Endothelium-independent relaxation in response to NO donor sodium nitroprusside was similar between IS and control groups. Together, our data suggest that IS promotes worsened endothelial dysfunction postKTx, which may contribute to the sustained CVD risk. Full article