Search Results (128)

p-Cresyl sulfate (PCS) is associated with endothelial injury and adverse cardiovascular outcomes. However, its association with endothelial function in patients on peritoneal dialysis (PD) remains unclear. In this cross-sectional study, 82 patients receiving PD were enrolled. Serum PCS concentrations were quantified using high-performance liquid chromatography–mass spectrometry. Endothelial function was evaluated by digital thermal monitoring (DTM), and vascular reactivity was stratified based on vascular reactivity index (VRI) values into good (>2.0), intermediate (1.0–1.9), and poor (<1.0). Overall, 46.3%, 43.9%, and 9.8% of participants had poor, intermediate, and good vascular reactivity, respectively. Poor reactivity was associated with a higher prevalence of diabetes (p = 0.018), old age (p < 0.001), higher waist circumference (p = 0.013), serum C-reactive protein levels (p = 0.010), and PCS levels (p < 0.001) and lower diastolic blood pressure (p = 0.032) and serum creatinine levels (p = 0.005). Higher serum log-transformed PCS levels were associated with reduced VRI after adjustment for covariates (p < 0.001). In multivariable models adjusted for potential confounders, PCS was independently associated with poor vascular reactivity (p = 0.029), with consistent findings observed across penalized regression analyses (all p < 0.001). An inverse relationship was observed between serum PCS levels and endothelial function in patients undergoing PD. Full article

Chronic kidney disease (CKD) is associated with a markedly increased risk of cardiovascular (CV) morbidity and mortality that cannot be fully explained by traditional risk factors. Emerging evidence highlights the central role of the gut–kidney–heart axis, whereby gut microbiota dysbiosis promotes the generation and systemic accumulation of uremic toxins, including indoxyl sulfate (IS), p-cresyl sulfate (PCS), and trimethylamine N-oxide (TMAO). These metabolites contribute to endothelial dysfunction, oxidative stress, inflammation, and vascular remodeling, thereby accelerating CV disease progression in CKD. Dietary patterns represent a key modifiable factor influencing gut microbiota composition and metabolic activity. The Mediterranean diet, characterized by high intake of plant-based foods, dietary fiber, and polyphenols, and low consumption of red and processed meats, has emerged as a promising microbiota-targeted strategy. It promotes saccharolytic fermentation, enhances short-chain fatty acid production, and reduces proteolytic pathways responsible for uremic toxin generation. Accumulating evidence from observational studies, meta-analyses, and dietary intervention trials suggests that adherence to Mediterranean and plant-based dietary patterns is associated with reduced uremic toxin burden, improved renal outcomes, and lower CV risk in CKD populations. However, direct interventional evidence linking Mediterranean diet adherence to changes in specific uremic toxin levels remains limited. This narrative review summarizes current evidence on diet–microbiota interactions in CKD and highlights the Mediterranean diet as a biologically plausible strategy for targeting the gut–kidney–heart axis. Future well-designed randomized controlled trials (RCTs) are needed to confirm causal relationships and support clinical implementation. Full article

Background: p-Cresyl sulfate (PCS) has been linked to vascular dysfunction through endothelial injury and vascular remodeling. Peripheral artery disease (PAD), identified by a low ankle–brachial index (ABI), is associated with increased mortality in kidney transplant (KT) recipients. This study investigated the association between serum PCS levels and PAD (as defined by ABI) in KT recipients. Methods: This cross-sectional, single-center study included 90 KT recipients. Serum total PCS levels were quantified using liquid chromatography–mass spectrometry. ABI was measured using an automated oscillometric device, and PAD was defined as ABI < 0.9. Results: Among the 90 KT recipients, 20 (22.2%) met the ABI for PAD. Patients with ABI-defined PAD had a significantly higher prevalence of diabetes mellitus (p = 0.036) and serum PCS levels (p = 0.001). Multivariate logistic regression analysis adjusting for potential confounders revealed that serum PCS levels remained independently associated with PAD (odds ratio 1.254, 95% confidence interval 1.108–1.419; p < 0.001). PCS levels were inversely correlated with both left (r = −0.339, p = 0.001) and right (r = −0.357, p < 0.001) ABIs. The association remained consistent in penalized regression models. Conclusions: Higher serum PCS levels were independently associated with ABI-defined PAD in KT recipients. The findings indicate that residual uremic toxin burden may contribute to peripheral vascular disease despite the restoration of renal function following transplantation. Full article

Background/Objectives: Protein-bound uremic toxins (PBUTs), particularly p-cresyl sulfate (PCS) and indoxyl sulfate (IS), are associated with cardiovascular toxicity and increased mortality. Conventional hemodialysis (HD) removes PBUTs poorly, and the efficacy of medium cut-off (MCO) dialyzer membranes remains uncertain. Furthermore, PBUT production is influenced by gut microbial metabolism and can be modified through diet. We hypothesized that MCO dialysis would provide superior clearance of PCS and IS compared with online hemodiafiltration (OL-HDF), and that combining MCO dialysis with increased dietary fiber and short-chain fatty acid (SCFA) intake would further reduce PBUT levels. Methods: In this prospective randomized trial, 62 maintenance HD patients underwent a 2-week wash-in period with high-flux HD (HF-HD) and were then randomized to MCO-HD (EXP) or OL-HDF (CON). After a 4-week intervention with the assigned dialysis modality, both groups continued with the same dialysis treatment and received an 8-week dietary intervention consisting of 19 g/day fiber and 1 g/day sodium propionate. The study concluded with a 4-week wash-out period on HF-HD. Primary outcomes were total serum PCS and IS levels measured at four timepoints. Results: Fifty-two patients completed the study. No significant changes in PCS or IS were observed after the dialysis-only intervention. PCS levels remained stable throughout the study. When the aligned dialysis regimen was combined with the dietary intervention, IS levels were significantly lower in the CON than in the EXP group (31.5 ± 10.3 vs. 42.0 ± 15.8 µmol/L; p = 0.006), with a partial rebound after wash-out in the CON group (39.6 ± 20.9 µmol/L; p = 0.003). Conclusions: While MCO-HD and OL-HDF had a similar effect on serum PCS and IS concentrations, only OL-HDF combined with the dietary intervention significantly reduced IS levels. Full article

Patients with chronic kidney disease (CKD) have a markedly increased cardiovascular risk that is not fully explained by traditional risk factors. Gut-derived uremic toxins, indoxyl sulfate (IS), indole-3-acetic acid (IAA), and p-cresyl sulfate (pCS), are poorly cleared by dialysis and may contribute to vascular damage. This cross-sectional observational study included 70 patients with CKD under different clinical conditions (pre-dialysis, peritoneal dialysis, hemodialysis, and kidney transplantation) and 17 healthy controls. Serum levels of IS, IAA, pCS and Klotho were measured, and vascular damage was assessed by carotid intima–media thickness (IMT) using ultrasound. CKD patients showed higher concentrations of IS, IAA, and pCS compared with controls, with the highest levels observed in hemodialysis patients. Peritoneal dialysis was associated with elevated IS and pCS, whereas in kidney transplantation, IS and IAA levels did not differ significantly from controls, and pCS remained elevated. Carotid IMT was higher in patients with diabetes and those undergoing hemodialysis. IAA correlated significantly with left/mean IMT, and mean IMT was the only parameter associated with previous cardiovascular events. These findings suggest that gut-derived uremic toxins, particularly IAA, might be associated with subclinical vascular damage in advanced CKD, although larger studies are needed to confirm these associations. Full article

Chronic kidney disease (CKD), especially diabetic kidney disease (DKD), is characterized not only by progressive loss of renal function but also by profound metabolic disturbances, including insulin resistance (IR). Emerging evidence implicates gut-derived uremic toxins as mediators linking intestinal dysbiosis to metabolic and renal injury. Several microbial metabolites, for example, indoxyl sulfate, p-cresyl sulfate, and trimethylamine-N-oxide, are known to accumulate in CKD due to decreased renal excretion and altered tubular secretion. In vitro and in vivo experiments indicate that these gut-derived nephrotoxins impair insulin signaling pathways in cells. This results in increased production of reactive oxygen species, activation of stress kinases, higher levels of inflammatory cytokines, and inhibitory serine phosphorylation of insulin receptor substrates. Consequently, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling is impaired, reducing cellular glucose uptake. At the same time, these toxins induce endothelial dysfunction and mitochondrial damage, not only causing systemic IR but also contributing to the progression of kidney disease. Observational data link higher plasma toxin levels with components of IR, rapid loss of renal function as measured by estimated glomerular filtration rate, and a high risk of cardiovascular events in CKD patients. Although causality in humans remains unproven, interventions targeting the microbiota, toxin binding, and oxidative stress pathways show promise. We propose an integrated gut–kidney–metabolic framework in which dysbiosis-driven toxin production may amplify IR and DKD progression. Full article

Chronic kidney disease (CKD) is a progressive condition associated with metabolic disturbances, systemic inflammation, and the accumulation of gut-derived uremic toxins. Increasing evidence highlights the role of gut microbiota dysbiosis in the progression of CKD through the gut–kidney axis. Consequently, microbiome-targeted nutritional strategies, including probiotics, prebiotics, and synbiotics, have emerged as promising complementary approaches to modulate intestinal microbial composition and metabolic functions. This review summarizes and critically evaluates the current clinical evidence regarding the use of these interventions in CKD patients. Clinical studies indicate that supplementation with probiotics, prebiotics, and synbiotic formulations may promote beneficial shifts in the composition of the gut microbiota, enhance saccharolytic fermentation, and increase the production of short-chain fatty acids (SCFAs). These changes have been associated with reduced circulating levels of gut-derived uremic toxins such as indoxyl sulfate and p-cresyl sulfate, as well as with the attenuation of systemic inflammation and oxidative stress. However, available trials remain heterogeneous in terms of study design, probiotic strains, prebiotic substrates, dosing regimens, and patient populations, and are frequently limited by small sample sizes and short intervention durations. As a result, evidence for improvements in renal function and long-term clinical outcomes remains inconclusive. While synbiotics may offer theoretical advantages by combining microbial supplementation with targeted substrates that support microbial growth and metabolic activity, current evidence does not consistently demonstrate superior clinical efficacy. Overall, these interventions often improve surrogate biomarkers, but their effects on renal function and hard clinical outcomes remain uncertain. Larger, longer-duration multicenter randomized controlled trials with standardized formulations are needed to establish their clinical utility and to better elucidate microbiota–host interactions in CKD. Advancing this field may support the development of personalized microbiome-based therapeutic strategies aimed at modulating the gut–kidney axis and ultimately improving clinical outcomes in CKD patients. Full article

Diagnosis of atypical parkinsonian syndromes (APS), including progressive supranuclear palsy (PSP) and multiple system atrophy (MSA), rely on clinical criteria that often result in misclassification or delayed confirmation. Cerebrospinal fluid (CSF) metabolomics offers the potential to identify disease-specific biochemical “fingerprints”. The aim of the study is to identify CSF metabolomic biomarkers that distinguish PSP and MSA from each other and from non-neurodegenerative controls. Targeted mass spectrometry-based metabolomics was performed on CSF samples from 30 patients with MSA, 41 with PSP, and 30 age- and sex-matched non-neurodegenerative controls. Global metabolomic profiles showed no clear group separation. Both PSP and MSA showed elevated gut-derived metabolites p-cresyl sulfate and deoxycholic acid versus controls. In PSP, decreased cortisone and increased hexosylceramide d18:1/24:1 were observed, whereas in MSA, dihydroxyphenylalanine was elevated alongside homoarginine and creatinine. In the direct comparison of APS, levels of α-aminoadipic acid were increased in PSP compared to MSA. Pathway analysis highlighted disrupted glycerophospholipid metabolism in both APS disorders. Distinct metabolite panels mainly combining membrane-associated lipids, gut-derived and neurotransmitter-related metabolites demonstrated high diagnostic accuracy for distinguishing PSP and MSA from control groups (AUC = 0.95 for PSP and AUC = 0.98 for MSA), while a separate panel showed moderate performance in differentiating PSP from MSA (AUC = 0.85). Distinct but partially overlapping CSF metabolomic profiles characterize PSP and MSA. These metabolomic fingerprints highlight gut–brain axis involvement, alterations in cell membrane-related lipid metabolism, and disease-specific changes in neurotransmitter-related metabolites. Further, a panel of these metabolites showed strong potential as diagnostic biomarkers. Full article

Background: Vascular calcification (VC) affects up to 90% of patients with end-stage renal disease and increases cardiovascular mortality 3- to 5-fold. Once considered passive mineral deposition, VC is now recognized as an active, toxin-driven process orchestrating vascular smooth muscle cell transdifferentiation, endothelial dysfunction, and matrix remodeling. However, current uremic toxin classifications remain biochemically oriented, providing limited clinical guidance for risk stratification and therapeutic selection. Methods: This comprehensive review reframes uremic toxin-driven VC through an integrated phenotypic lens, synthesizing molecular mechanisms, clinical biomarkers, and therapeutic targets into a unified translational framework. Results: We propose five mechanistic-clinical phenotypes representing distinct biological trajectories of vascular injury. These include (1) inflammatory-oxidative (dominated by indoxyl sulfate, p-cresyl sulfate, NLRP3 inflammasome activation), (2) mineral-metabolic (hyperphosphatemia, FGF23 excess, Klotho deficiency), (3) epigenetic-senescent (histone modifications, microRNA dysregulation, cellular senescence), (4) endocrine cross-talk (vitamin D, PTH, gut-derived metabolites), and (5) integrated toxic continuum (convergence of multiple pathways in advanced disease). A comprehensive biomarker panel spanning inflammatory markers, mineral metabolism parameters, epigenetic indicators, and endocrine-gut metabolites enables phenotypic stratification and therapeutic monitoring. Emerging therapies—including tissue-nonspecific alkaline phosphatase inhibition, ectonucleotide pyrophosphatase/phosphodiesterase 1 enzyme replacement, vitamin K₂ activation, senolytic agents, and SNF472 crystal-growth blockade—are mapped to their optimal phenotypic contexts. Conclusions: This phenotype-oriented paradigm transforms VC from an inevitable complication into a targetable and potentially reversible manifestation of uremic toxicity, establishing a translational foundation for precision-based vascular medicine in chronic kidney disease. The framework enables biomarker-guided patient stratification, rational therapeutic selection, and phenotype-enriched clinical trial design. Full article

Background: Chronic kidney disease (CKD) represents a state of persistent, sterile low-grade inflammation in which sustained innate immune activation accelerates renal decline and cardiovascular complications. Diet-induced gut dysbiosis and intestinal barrier dysfunction lower mucosal immune tolerance, promote metabolic endotoxemia, and position the gut as an upstream modulator of systemic inflammatory signaling along the gut–kidney axis. Scope: Most studies address microbiota-derived metabolites, food-derived bioactive peptides, or omega-3 fatty acids separately. This review integrates evidence across these domains and examines their convergent actions on epithelial barrier integrity, immune polarization, oxidative-inflammatory stress, and inflammasome-dependent pathways relevant to CKD progression. Key mechanisms: CKD-associated dysbiosis is characterized by reduced short-chain fatty acid (SCFA) production and increased generation and accumulation of uremic toxins and co-metabolites, including indoxyl sulfate, p-cresyl sulfate, trimethylamine N-oxide, and altered bile acids. Reduced SCFA availability weakens tight junction-dependent barrier function and regulatory immune programs, favoring Th17-skewed inflammation and endotoxin translocation. Bioactive peptides modulate inflammatory mediator networks and barrier-related pathways through effects on NF-κB/MAPK signaling and redox balance, while omega-3 fatty acids and specialized pro-resolving mediators support resolution-phase immune responses. Across these modalities, shared control points include barrier integrity, metabolic endotoxemia, oxidative stress, and NLRP3 inflammasome activation. Conclusions: Although evidence remains heterogeneous and largely preclinical, combined nutritional modulation targeting these convergent pathways may offer greater immunomodulatory benefit than isolated interventions. Future multi-omics-guided, factorial trials are required to define responder phenotypes and translate precision immunonutrition strategies into clinical CKD care. Full article

Chronic kidney disease (CKD), which affects over 850 million individuals globally, is increasingly regarded as a systemic condition in which the gut microbiota represents a key pathogenic node. This review provides an integrated overview of mechanistic, translational and clinical data implicating the gut–kidney axis in CKD. The CKD-associated microbiota displays a characteristic dysbiosis, marked by depletion of short-chain fatty acid–producing commensals, overgrowth of proteolytic and urease-expressing taxa and disruption of epithelial barrier integrity. These disturbances favor the generation and systemic accumulation of gut-derived uremic toxins, most notably indoxyl sulfate, p-cresyl sulfate, indole-3-acetic acid and trimethylamine-N-oxide, which promote endothelial dysfunction, vascular calcification, fibrosis and chronic inflammation, thereby hastening renal function loss and heightening cardiovascular risk. Microbiome-directed interventions, including dietary modification, prebiotics, probiotics, synbiotics, intestinal dialysis, fecal microbiota transplantation, gut-acting sorbents and nephroprotective phytochemicals, are summarized with emphasis on their effects on uremic toxin burden and clinical surrogates. System-level implications of the gut–kidney axis for cardiovascular disease, immunosenescence and sarcopenia are discussed, together with future priorities for integrating multi-omics profiling and precision microbiome-based strategies into nephrology practice. Full article

Cardiovascular diseases are a major cause of morbidity and mortality in chronic kidney disease (CKD) patients. Integrin-linked kinase (ILK) regulates integrin–extracellular matrix interactions and vascular integrity. This study investigated the role of ILK in CKD-associated vascular alterations. An adenine-supplemented diet induced a progressive CKD in wild-type (WT) and conditional ILK knock-down (cKD-ILK) mice. Aortic tissue was collected for histology and RT-qPCR analysis. Moreover, aortas were incubated ex vivo with the uremic toxins p-cresyl sulfate and indoxyl sulfate. In vitro, human aortic vascular smooth muscle cells were exposed to uremic toxins, and the effect of siRNA-mediated ILK silencing was tested. Aortas of adenine-fed WT mice showed a progressive increase in ILK expression, morphological alterations, and increased fibrosis, which was not observed in cKD-ILK aortas, compared to control mice. Statistically significant correlations between vascular content of ILK and fibrosis markers were observed. Ex vivo, uremic toxins increased ILK and fibrosis protein expression in WT aortas but not in cKD-ILK. In vitro, uremic toxins increased ILK activity and fibrosis markers, like collagen, while ILK-deleted cells prevented collagen increase. ILK depletion prevents CKD-associated vascular fibrosis, suggesting ILK as a potential therapeutic target to prevent arterial alterations in renal patients. Full article

ST-elevation myocardial infarction (STEMI) remains a major health concern despite advances in care. Indoxyl sulfate (IS) and p-cresyl-sulfate (p-CS) are gut-derived uremic toxins linked to higher morbidity and mortality in patients with chronic kidney disease (CKD). IS has been identified as an independent predictor of major adverse cardiovascular events (MACE) after STEMI, but data on p-CS are lacking. This study assessed the predictive value of IS and p-CS in STEMI patients with preserved renal function (cohort # NCT03070496). Plasma IS and p-CS were measured in 260 patients with STEMI who underwent primary coronary angiography. Samples collected 4 h after inclusion were analyzed using ultra-performance liquid chromatography with fluorescence detection. Optimal cut-offs were determined by the Youden index, and associations with MACE were evaluated by log-rank tests and Cox regression. Among 234 analyzed patients, 11.5% experienced MACE within one year. IS and p-CS levels were higher in the MACE group (IS: 3.14 vs. 2.19 µmol/L, p < 0.05; p-CS: 6.76 vs. 2.70 µmol/L, p < 0.01). Elevated p-CS independently predicted MACE (HR 3.79, 95% CI 1.29–11.17, p < 0.05), whereas IS lost significance after adjusting for kidney function. In STEMI patients, plasma p-CS is a stronger independent predictor of MACE than IS, highlighting its potential role in the gut–heart axis. Full article

The interaction between gut microbiota dysbiosis and CKD progression via the “gut–kidney axis” is increasingly recognized. Gut-derived uremic toxins (e.g., indoxyl sulfate and p-cresyl sulfate) accumulate systemically, while beneficial metabolites like short-chain fatty acids (SCFAs) decrease, contributing to inflammation, oxidative stress, and kidney fibrosis. Traditional Chinese Medicine (TCM), including complex formulae, single herbs, and active ingredients, has long been used to manage CKD. Emerging evidence—primarily from animal studies—highlights its potential to alleviate the disease by modulating the gut microbiota. This review summarizes how TCM interventions re-establish gut microbial symbiosis by regulating microbial composition, reducing toxin load, and reinforcing intestinal barrier integrity, thereby ameliorating systemic inflammation and protecting kidney function. Targeting the gut microbiota represents a promising therapeutic frontier for CKD, and TCM offers a rich resource for developing novel microbiota-modulating strategies. However, future research must focus on validating molecular mechanisms, standardizing TCM preparations, and conducting rigorous clinical trials to facilitate clinical translation. Full article

Aim: To explore the associations between protein-bound uraemic toxins (PBTs), fibre intake and patient-focused outcomes in patients on kidney replacement therapy. Background: Despite removal of small water-soluble uraemic toxins, dialysis patients continue to experience high morbidity and mortality. Recent evidence suggests strong associations between PBTs and poorer patient outcomes and symptom burden. Reducing the generation of PBTs by increasing dietary fibre may be an alternate approach to better patient outcomes. Method: This was a cross-sectional study of haemodialysis (HD), peritoneal dialysis (PD) and kidney transplant patients to determine the associations between uraemic toxins [p-cresyl sulfate (PCS) and indoxyl sulfate (IS)], fibre intake and patient-focused outcomes, incorporating the Integrated Palliative Outcome Scale-Renal (IPOS-renal) and EQ-5D-5L to determine symptom burden and quality of life, while physical capacity was determined using the timed up and go(TUG) test and handgrip strength (HGS). Results: Ninety participants completed the study (n = 30 in each group). There was a correlation between PBTs and the IPOS-renal score, where higher toxin levels were associated with a higher symptom burden. This was the strongest for PCS, where the significance remained after accounting for age and co-morbidities (p < 0.05). Higher PBT levels were also associated with lower HGS (p < 0.05). There was a negative correlation between fibre intake and PBTs, serum PCS (r = −0.36, p < 0.05) and serum IS (r = −0.27, p < 0.05). Lower fibre intake was also associated with a higher symptom burden measured by the IPOS-renal (p < 0.05). Transplant patients consistently performed better, with a reduced symptom burden and improved physical ability compared to dialysis patients. Conclusion: PBTs were associated with symptom burden, and lower physical ability was associated with both PBTs and patient-focused outcomes, and this needs to be further investigated in larger studies. Full article