Impact of Uremic Toxins on Endothelial Dysfunction in Chronic Kidney Disease: A Systematic Review

Sulfation pathways in the maintenance of functional beta-cell mass and implications for diabetes

Diabetes Type 1 and Type 2 are widely occurring diseases. In spite of a vast amount of biomedical literature about diabetic processes in general, links to certain biological processes are only becoming evident these days. One such area of biology is the sulfation of small molecules, such as steroid hormones or metabolites from the gastrointestinal tract, as well as larger biomolecules, such as proteins and proteoglycans. Thus, modulating the physicochemical propensities of the different sulfate acceptors, resulting in enhanced solubility, expedited circulatory transit, or enhanced macromolecular interaction. This review lists evidence for the involvement of sulfation pathways in the maintenance of functional pancreatic beta-cell mass and the implications for diabetes, grouped into various classes of sulfated biomolecule. Complex heparan sulfates might play a role in the development and maintenance of beta-cells. The sulfolipids sulfatide and sulfo-cholesterol might contribute to beta-cell health. In beta-cells, there are only very few proteins with confirmed sulfation on some tyrosine residues, with the IRS4 molecule being one of them. Sulfated steroid hormones, such as estradiol-sulfate and vitamin-D-sulfate, may facilitate downstream steroid signaling in beta-cells, following de-sulfation. Indoxyl sulfate is a metabolite from the intestine, that causes kidney damage, contributing to diabetic kidney disease. Finally, from a technological perspective, there is heparan sulfate, heparin, and chondroitin sulfate, that all might be involved in next-generation beta-cell transplantation. Sulfation pathways may play a role in pancreatic beta-cells through multiple mechanisms. A more coherent understanding of sulfation pathways in diabetes will facilitate discussion and guide future research.

Associations of circulating total p-cresylsulfate and indoxyl sulfate concentrations with central obesity in patients with stable coronary artery disease: sex-specific insights

BACKGROUND/AIMS

Elevated systemic inflammation, common in obesity, increases cardiovascular disease risk. Obesity is linked to a pro-inflammatory gut microbiota that releases uremic toxins like p-cresylsulfate (PCS) and indoxyl sulfate (IS), which are implicated in coronary atherosclerosis, insulin resistance, and chronic kidney disease. This study examines the relationship between total PCS and IS levels and central obesity in patients with stable coronary artery disease (CAD).

METHODS

A cross-sectional study was conducted on 373 consecutive patients with stable CAD from a single center. Serum levels of total PCS and IS were measured using an Ultra Performance LC System. Central obesity was evaluated using a body shape index (ABSI) and conicity index (CI). Six obesity-related proteins were also analyzed. Structural equation modeling (SEM) assessed direct and indirect effects of total PCS, IS, and the six obesity-related proteins on central obesity.

RESULTS

Significant positive correlations were found between total PCS and IS with waist-to-hip ratio (WHR) (r = 0.174, p = 0.005 for total PCS; r = 0.144, p = 0.021 for IS), CI (r = 0.273, p < 0.0001 for total PCS; r = 0.260, p < 0.0001 for IS), and ABSI (r = 0.297, p < 0.0001 for total PCS; r = 0.285, p < 0.0001 for IS) in male patients, but not in female patients. Multivariate analysis showed higher odds ratios (ORs) for elevated CI (OR = 3.18, 95% CI: 1.54-6.75, p = 0.002) and ABSI (OR = 3.28, 95% CI: 1.54-7.24, p = 0.002) in patients with high PCS levels, and elevated CI (OR = 2.30, 95% CI: 1.15-4.66, p = 0.018) and ABSI (OR = 2.22, 95% CI: 1.07-4.72, p = 0.033) in those with high IS levels, compared to those with low toxin levels. SEM analysis indicated that total PCS and IS directly impacted central obesity indices and indirectly influenced central adiposity measures like WHR through high sensitivity C-reactive protein (hs-CRP) (β = 0.252, p < 0.001).

CONCLUSIONS

Circulating total PCS and IS contribute to central obesity in male patients with stable CAD, partially mediated by hs-CRP.

The SGLT2 inhibitor dapagliflozin ameliorates renal fibrosis in hyperuricemic nephropathy

Hyperuricemic nephropathy (HN) is a global metabolic disorder characterized by uric acid (UA) metabolism dysfunction, resulting in hyperuricemia (HUA) and tubulointerstitial fibrosis (TIF). Sodium-dependent glucose transporter 2 inhibitor, dapagliflozin, has shown potential in reducing serum UA levels in patients with chronic kidney disease (CKD), though its protective effects against HN remain uncertain. This study investigates the functional, pathological, and molecular changes in HN through histological, biochemical, and transcriptomic analyses in patients, HN mice, and UA-stimulated HK-2 cells. Findings indicate UA-induced tubular dysfunction and fibrotic activation, which dapagliflozin significantly mitigates. Transcriptomic analysis identifies estrogen-related receptor α (ERRα), a downregulated transcription factor in HN. ERRα knockin mice and ERRα-overexpressed HK-2 cells demonstrate UA resistance, while ERRα inhibition exacerbates UA effects. Dapagliflozin targets ERRα, activating the ERRα-organic anion transporter 1 (OAT1) axis to enhance UA excretion and reduce TIF. Furthermore, dapagliflozin ameliorates renal fibrosis in non-HN CKD models, underscoring the therapeutic significance of the ERRα-OAT1 axis in HN and CKD.

Cellular metabolism changes in atherosclerosis and the impact of comorbidities

Cell activation and nutrient dysregulation are common consequences of atherosclerosis and its preceding risk factors, such as hypertension, dyslipidemia, and diabetes. These diseases may also impact cellular metabolism and consequently cell function, and the other way around, altered cellular metabolism can impact disease development and progression through altered cell function. Understanding the contribution of altered cellular metabolism to atherosclerosis and how cellular metabolism may be altered by co-morbidities and atherosclerosis risk factors could support the development of novel strategies to lower the risk of CVD. Therefore, we briefly review disease pathogenesis and the principles of cell metabolic pathways, before detailing changes in cellular metabolism in the context of atherosclerosis and comorbidities. In the hypoxic, inflammatory and hyperlipidemic milieu of the atherosclerotic plaque riddled with oxidative stress, metabolism shifts to increase anaerobic glycolysis, the pentose-phosphate pathway and amino acid use. We elaborate on metabolic changes for macrophages, neutrophils, vascular endothelial cells, vascular smooth muscle cells and lymphocytes in the context of atherosclerosis and its co-morbidities hypertension, dyslipidemia, and diabetes. Since causal relationships of specific key genes in a metabolic pathway can be cell type-specific and comorbidity-dependent, the impact of cell-specific metabolic changes must be thoroughly explored in vivo, with a focus on also systemic effects. When cell-specific treatments become feasible, this information will be crucial for determining the best metabolic intervention to improve atherosclerosis and its interplay with co-morbidities.

Post-translational modifications in kidney diseases and associated cardiovascular risk

Patients with chronic kidney disease (CKD) are at an increased cardiovascular risk compared with the general population, which is driven, at least in part, by mechanisms that are uniquely associated with kidney disease. In CKD, increased levels of oxidative stress and uraemic retention solutes, including urea and advanced glycation end products, enhance non-enzymatic post-translational modification events, such as protein oxidation, glycation, carbamylation and guanidinylation. Alterations in enzymatic post-translational modifications such as glycosylation, ubiquitination, acetylation and methylation are also detected in CKD. Post-translational modifications can alter the structure and function of proteins and lipoprotein particles, thereby affecting cellular processes. In CKD, evidence suggests that post-translationally modified proteins can contribute to inflammation, oxidative stress and fibrosis, and induce vascular damage or prothrombotic effects, which might contribute to CKD progression and/or increase cardiovascular risk in patients with CKD. Consequently, post-translational protein modifications prevalent in CKD might be useful as diagnostic biomarkers and indicators of disease activity that could be used to guide and evaluate therapeutic interventions, in addition to providing potential novel therapeutic targets.

Endothelial dysfunction: molecular mechanisms and clinical implications

Cardiovascular disease (CVD) and its complications are a leading cause of death worldwide. Endothelial dysfunction plays a crucial role in the initiation and progression of CVD, serving as a pivotal factor in the pathogenesis of cardiovascular, metabolic, and other related diseases. The regulation of endothelial dysfunction is influenced by various risk factors and intricate signaling pathways, which vary depending on the specific disease context. Despite numerous research efforts aimed at elucidating the mechanisms underlying endothelial dysfunction, the precise molecular pathways involved remain incompletely understood. This review elucidates recent research findings on the pathophysiological mechanisms involved in endothelial dysfunction, including nitric oxide availability, oxidative stress, and inflammation-mediated pathways. We also discuss the impact of endothelial dysfunction on various pathological conditions, including atherosclerosis, heart failure, diabetes, hypertension, chronic kidney disease, and neurodegenerative diseases. Furthermore, we summarize the traditional and novel potential biomarkers of endothelial dysfunction as well as pharmacological and nonpharmacological therapeutic strategies for endothelial protection and treatment for CVD and related complications. Consequently, this review is to improve understanding of emerging biomarkers and therapeutic approaches aimed at reducing the risk of developing CVD and associated complications, as well as mitigating endothelial dysfunction.

Identification of renal protective gut microbiome derived-metabolites in diabetic chronic kidney disease: An integrated approach using network pharmacology and molecular docking

Metabolites from the gut microbiota define molecules in the gut-kidney cross talks. However, the mechanistic pathway by which the kidneys actively sense gut metabolites and their impact on diabetic chronic kidney disease (DCKD) remains unclear. This study is an attempt to investigate the gut microbiome metabolites, their host targeting genes, and their mechanistic action against DCKD. Gut microbiome, metabolites, and host targets were extracted from the gutMgene database and metabolites from the PubChem database. DCKD targets were identified from DisGeNET, GeneCard, NCBI, and OMIM databases. Computational examination such as protein-protein interaction networks, enrichment pathway, identification of metabolites for potential targets using molecular docking, hubgene-microbes-metabolite-samplesource-substrate (HMMSS) network architecture were executed using Network analyst, ShinyGo, GeneMania, Cytoscape, Autodock tools. There were 574 microbial metabolites, 2861 DCKD targets, and 222 microbes targeting host genes. After screening, we obtained 27 final targets, which are used for computational examination. From enrichment analysis, we found NF-ΚB1, AKT1, EGFR, JUN, and RELA as the main regulators in the DCKD development through mitogen activated protein kinase (MAPK) pathway signalling. The (HMMSS) network analysis found F.prausnitzi, B.adolescentis, and B.distasonis probiotic bacteria that are found in the intestinal epithelium, colonic region, metabolize the substrates like tryptophan, other unknown substrates might have direct interaction with the NF-kB1 and epidermal growth factor receptor (EGFR) targets. On docking of these target proteins with 3- Indole propionic acid (IPA) showed high binding energy affinity of -5.9 kcal/mol and -7.4kcal/mol. From this study we identified, the 3 IPA produced by F. prausnitzi A2-165 was found to have renal sensing properties inhibiting MAPK/NF-KB1 inflammatory pathway and would be useful in treating CKD in diabetics.

Natural antagonistic flavones for AhR inhibit indoxyl sulfate-induced inflammatory gene expression in vitro and renal pathological damages in vivo

Background

Uremic toxin indoxyl sulfate (IS) induces vascular inflammation, a crucial event in renal failure, and vascular complications in patients with chronic kidney disease (CKD). In endothelial cells, IS increases the production of inflammatory cytokines partially via the activation of the aryl hydrocarbon receptor (AhR), and several food flavonoids have been reported to act as antagonists of AhR.

Objective

This study aimed to investigate whether antagonistic flavonoids can attenuate IS-induced inflammatory responses in vascular endothelial cells in vitro and renal failure in vivo.

Design

Human umbilical vein endothelial cells (HUVECs) pretreated with the flavones apigenin, chrysin, or luteolin were stimulated with IS. Expression levels of genes involved in AhR signaling, inflammatory cytokine production, and reactive oxygen species (ROS) production were analyzed. Uninephrectomized mice were orally administered chrysin and received daily intraperitoneal injections of IS for 4 weeks.

Results

In HUVECs, IS upregulated the mRNA expression of AhR-targeted genes (CYP1A1 and AhRR), and genes involved in inflammation (NOX4, MCP-1, IL-6, and COX2) and monocyte invasion/adhesion (ICAM1). All three flavones attenuated the IS-induced increase in the expression of these mRNAs. They also suppressed the IS-induced nuclear translocation of AhR and intracellular ROS production. Furthermore, IS-induced phosphorylation of the signal transducer and activator of transcription 3 (STAT3) was inhibited by treatment with these flavones. The results of in-vivo experiments showed that administration with chrysin attenuated the elevation of blood urea nitrogen levels and AhR-target gene expression and the pathological impairment of renal tissues in mice, regardless of higher serum levels of IS.

Conclusions

Natural food flavones antagonizing AhR exerted protective effects against IS-induced inflammation through the inhibition of the AhR-STAT3 pathway in HUVECs. Moreover, chrysin ameliorated IS-induced renal dysfunction in a mouse model of CKD. These flavonoids could be a therapeutic strategy for vascular inflammation in CKD.

C-Phycoerythrin Prevents Chronic Kidney Disease-Induced Systemic Arterial Hypertension, Avoiding Oxidative Stress and Vascular Dysfunction in Remanent Functional Kidney

Chronic kidney disease (CKD) is a burden in low- and middle-income countries, and a late diagnosis with systemic arterial hypertension (SAH) is the major complication of CKD. C-phycoerythrin (CPE) is a bioactive compound derived from Phormidium persicinum that presents anti-inflammatory and antioxidant effects in vitro and nephroprotective effects in vivo. In the current study, we determine the antihypertensive effect of CPE in a 5/6 nephrectomy-induced CKD model using twenty normotensives male Wistar rats, grouped into four groups (n = 5): sham; sham + CPE; 5/6 nephrectomy (NFx); and NFx + CPE. Treatment started a week post-surgery and continued for five weeks, with weekly hemodynamic evaluations. Following treatment, renal function, oxidative stress, and the expression of vascular dysfunction markers were assessed. The renal function analysis revealed CKD hyperfiltration, and the hemodynamic evaluation showed that SAH developed at the third week. AT1R upregulation and AT2R downregulation together with Mas1/p-Akt/p-eNOS axis were also observed. CPE treatment mitigated renal damage, preserved renal function, and prevented SAH with the modulation of the vasodilative AT1R, AT2R, and Mas1/pAKT/peNOS axis. This result reveals that CPE prevented CKD progression to SAH by avoiding oxidative stress and vascular dysfunction in the kidneys.

Association of retinal age gap with chronic kidney disease and subsequent cardiovascular disease sequelae: a cross-sectional and longitudinal study from the UK Biobank

Background

Chronic kidney disease (CKD) increases the risk of cardiovascular disease (CVD) and is more prevalent in older adults. Retinal age gap, a biomarker of aging based on fundus images, has been previously developed and validated. This study aimed to investigate the association of retinal age gap with CKD and subsequent CVD complications.

Methods

A deep learning model was trained to predict the retinal age using 19 200 fundus images of 11 052 participants without any medical history at baseline. Retinal age gap, calculated as retinal age predicted minus chronological age, was calculated for the remaining 35 906 participants. Logistic regression models and Cox proportional hazards regression models were used for the association analysis.

Results

A total of 35 906 participants (56.75 ± 8.04 years, 55.68% female) were included in this study. In the cross-sectional analysis, each 1-year increase in retinal age gap was associated with a 2% increase in the risk of CKD prevalence [odds ratio 1.02, 95% confidence interval (CI) 1.01-1.04, P = .012]. A longitudinal analysis of 35 039 participants demonstrated that 2.87% of them developed CKD in follow-up, and each 1-year increase in retinal age gap was associated with a 3% increase in the risk of CKD incidence (hazard ratio 1.03, 95% CI 1.01-1.05, P = .004). In addition, a total of 111 CKD patients (15.81%) developed CVD in follow-up, and each 1-year increase in retinal age gap was associated with a 10% increase in the risk of incident CVD (hazard ratio 1.10, 95% CI 1.03-1.17, P = .005).

Conclusions

We found that retinal age gap was independently associated with the prevalence and incidence of CKD, and also associated with CVD complications in CKD patients. This supports the use of this novel biomarker in identifying individuals at high risk of CKD and CKD patients with increased risk of CVD.

Chronic Kidney Disease Increases Mortality and Reduces the Chance of a Favorable Outcome in Stroke Patients Treated with Mechanical Thrombectomy-Single-Center Study

Background/Objectives: Chronic kidney disease (CKD) is identified as a risk factor for the occurrence of ischemic stroke. There is substantial evidence that CKD is linked to a worse prognosis and higher mortality rates in stroke patients. This study aimed to evaluate the characteristics and factors affecting favorable outcomes and mortality in patients treated using mechanical thrombectomy (MT) for ischemic stroke, with particular emphasis on patients suffering from CKD. Methods: The retrospective study included an analysis of data from 723 patients (139; 19.4% had CKD) with ischemic stroke treated with MT between March 2019 and July 2022. Results: Patients with CKD were significantly older (median age 76.5 vs. 65.65, p < 0.001) and more often female (59.7% vs. 42.6%, p < 0.001). CKD decreased the likelihood of achieving a favorable outcome (0-2 points in modified Rankin scale; OR: 0.56, CI95%: 0.38-0.81) and increased mortality (OR: 2.59, CI95%: 1.74-3.84) on the 90th day after stroke. In addition, CKD was associated with intracranial hemorrhage (ICH) in patients who underwent posterior circulation MT (13.85% vs. 50%, p = 0.022). In patients with CKD, inter alia, higher levels of C-reactive protein (OR: 0.94, CI95%: 0.92-0.99) reduced the chance of a favorable outcome. In addition, the occurrence of ICH in patients with CKD increased mortality on the 90th day after stroke (OR: 4.18, CI95%: 1.56-11.21), which was almost twice as high as in patients without CKD (OR: 2.29, CI95%: 1.54-3.40). Conclusions: Patients suffering from CKD had a lower probability of achieving a favorable outcome and had increased mortality following MT for ischemic stroke. It is crucial to understand the variations between patients with unimpaired and impaired renal function, as this could aid in predicting the outcomes of this method.

Production of Toxins by the Gut Microbiota: The Role of Dietary Protein

PURPOSE OF REVIEW

This narrative review will discuss how the intake of specific protein sources (animal and vegetable) providing specific amino acids can modulate the gut microbiota composition and generate toxins. A better understanding of these interactions could lead to more appropriate dietary recommendations to improve gut health and mitigate the risk of complications promoted by the toxic metabolites formed by the gut microbiota.

RECENT FINDINGS

Gut microbiota is vital in maintaining human health by influencing immune function and key metabolic pathways. Under unfavorable conditions, the gut microbiota can produce excess toxins, which contribute to inflammation and the breakdown of the integrity of the intestinal barrier. Genetic and environmental factors influence gut microbiota diversity, with diet playing a crucial role. Emerging evidence indicates that the gut microbiota significantly metabolizes amino acids from dietary proteins, producing various metabolites with beneficial and harmful effects. Amino acids such as choline, betaine, l-carnitine, tyrosine, phenylalanine, and tryptophan can increase the production of uremic toxins when metabolized by intestinal bacteria. The type of food source that provides these amino acids affects the production of toxins. Plant-based diets and dietary fiber are associated with lower toxin formation than animal-based diets due to the high amino acid precursors in animal proteins.

Association of endothelial dysfunction and peripheral arterial disease with sarcopenia in chronic kidney disease

BACKGROUND

Endothelial dysfunction and peripheral arterial disease (PAD), which disturb skeletal muscle microperfusion, are highly prevalent in patients with chronic kidney disease (CKD). We evaluated the association of endothelial dysfunction and PAD with sarcopenia in patients with non-dialysis CKD.

METHODS

This cross-sectional study included 420 patients with stages 3-5 non-dialysis CKD aged 69.0 ± 11.8 years. Skeletal muscle index (skeletal muscle mass/height2), handgrip strength, 6-m gait speed and strength of hip flexion and knee extension were measured. Sarcopenia was defined according to the Asian Working Group for Sarcopenia 2019. Endothelial dysfunction and PAD were assessed using the vascular reactivity index (VRI) and ankle-brachial index (ABI), respectively. A VRI < 1.0 was classified as poor endothelial function, and an ABI < 0.9 was defined as PAD. Additionally, endothelial and inflammatory biomarkers, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), asymmetric dimethylarginine, endothelin-1 (ET-1) and interleukin-6, were measured in a subgroup of 262 patients.

RESULTS

Among the participants, 103 (24.5%) were classified as having sarcopenia. Compared with patients without sarcopenia, those with sarcopenia had significantly lower ABI (1.04 ± 0.16 vs. 1.08 ± 0.15, P = 0.028 for the right ABI; 1.01 ± 0.16 vs. 1.06 ± 0.16, P = 0.002 for the left ABI) and VRI (0.83 ± 0.57 vs. 1.08 ± 0.56, P < 0.001) and had higher serum levels of ICAM-1 (P < 0.001), VCAM-1 (P = 0.003) and ET-1 (P = 0.037). Multivariate logistic regression revealed that, beyond age and body mass index, the average ABI (odds ratio [OR]: 0.81/0.1 increase; 95% confidence interval [CI]: 0.67-0.98; P = 0.032) and VRI (OR: 0.93/0.1 increase; 95% CI: 0.88-0.98; P = 0.010) were independently associated with sarcopenia. Among the endothelial biomarkers measured, ICAM-1 (OR: 2.47/1-SD increase; 95% CI: 1.62-3.75) and VCAM-1 (OR: 1.91/1-SD increase; 95% CI: 1.27-2.87) were independent predictors of sarcopenia. Group stratification based on the cut-offs of VRI and ABI showed that those with both poor VRI and ABI had the greatest risk for sarcopenia (OR: 4.22; 95% CI: 1.69-10.49), compared with those with normal VRI and ABI.

CONCLUSIONS

Endothelial dysfunction and PAD are independently associated with sarcopenia in patients with stages 3-5 CKD, suggesting the dominant role of vascular dysfunction in sarcopenia.

Roles of AhR/CYP1s signaling pathway mediated ROS production in uremic cardiomyopathy

PURPOSE

Uremic cardiomyopathy (UCM) is the leading cause of chronic kidney disease (CKD) related mortality. Uremic toxins including indoxyl sulfate (IS) play important role during the progression of UCM. This study was to explore the underlying mechanism of IS related myocardial injury.

METHODS

UCM rat model was established through five-sixths nephrectomy to evaluate its effects on blood pressure, cardiac impairment, and histological changes using echocardiography and histological analysis. Additionally, IS was administered to neonatal rat cardiomyocytes (NRCMs) and the human cardiomyocyte cell line AC16. DHE staining and peroxide-sensitive dye 2',7'-dichlorofluorescein diacetate (H2DCFDA) was conducted to assess the reactive oxygen species (ROS) production. Cardiomyocyte hypertrophy was estimated using wheat germ agglutinin (WGA) staining and immunofluorescence. Aryl hydrocarbon receptor (AhR) translocation was observed by immunofluorescence. The activation of AhR was evaluated by immunoblotting of cytochrome P450 1 s (CYP1s) and quantitative real-time PCR (RT-PCR) analysis of AHRR and PTGS2. Additionally, the pro-oxidative and pro-hypertrophic effects were evaluated using the AhR inhibitor CH-223191, the CYP1s inhibitor Alizarin and the ROS scavenger N-Acetylcysteine (NAC).

RESULTS

UCM rat model was successfully established, and cardiac hypertrophy, accompanied by increased blood pressure, and myocardial fibrosis. Further research confirmed the activation of the AhR pathway in UCM rats including AhR translocation and downstream protein CYP1s expression, accompanied with increasing ROS production detected by DHE staining. In vitro experiment demonstrated a translocation of AhR triggered by IS, leading to significant increase of downstream gene expression. Subsequently study indicated a close relationship between the production of ROS and the activation of AhR/CYP1s, which was effectively blocked by applying AhR inhibitor, CYP1s inhibitor and siRNA against AhR. Moreover, the inhibition of AhR/CYP1s/ROS pathway collectively blocked the pro-hypertrophic effect of IS-mediated cardiomyopathy.

CONCLUSION

This study provides evidence that the AhR/CYP1s pathway is activated in UCM rats, and this activation is correlated with the uremic toxin IS. In vitro studies indicate that IS can stimulate the AhR translocation in cardiomyocyte, triggering to the production of intracellular ROS via CYP1s. This process leads to prolonged oxidative stress stimulation and thus contributes to the progression of uremic toxin-mediated cardiomyopathy.

Effect of medium cut-off and high-flux hemodialysis membranes on blood pressure assessed by ambulatory blood pressure monitoring

BACKGROUND

Hypertension is one of the most critical risk factors for cardiovascular disease, which is the leading cause of death in hemodialysis (HD) patients. Medium cut-off (MCO) membrane increases the clearance of medium molecules, which could improve blood pressure (BP) control. This study aimed to compare the effect of MCO and high-flux hemodialysis membranes on BP assessed by ambulatory blood pressure monitoring (ABPM).

METHODS

This is a pre-established secondary analysis of a 28-week, randomized, open-label crossover clinical trial. Patients were randomized to HD with MCO or high-flux membranes over 12 weeks, followed by a 4-week washout period, and then switched to the alternate membrane treatment for 12 weeks. ABPM was started before the HD session and ended at least 24 h later in weeks 1, 12, 16, and 28.

RESULTS

32 patients, 59% male, with a mean age of 52.7 years, and 40% with unknown CKD etiology, were enrolled. The dialysis vintage was 8 years, and more than 70% of the patients had hypertension. Regarding 24-h BP control, morning diastolic BP showed an increase in the high-flux compared to stability in the MCO group (interaction effect, p = 0.039). The adjusted ANOVA models showed no significant difference in the morning BP levels between the groups. Considering only the period of the HD session, patients in the MCO, compared to those in the high-flux membrane group, showed greater BP stability during dialysis, characterized by smaller variation in the pre-post HD systolic and minimum systolic BP (treatment effect, p = 0.039, and p = 0.023, respectively).

CONCLUSIONS

MCO membrane seems to have a beneficial effect on morning BP and favors better BP stability during HD sessions.

Factors associated with early-onset intracranial aneurysms in patients with autosomal dominant polycystic kidney disease

BACKGROUND

Recently, the importance of attribute-based medicine has been emphasized. The effects of early-onset intracranial aneurysms on patients can be significant and long-lasting. Herein, we compared the factors associated with intracranial aneurysms in patients with autosomal dominant polycystic kidney disease (ADPKD) according to age categories (≥ 50 years, < 50 years).

METHODS

We included 519 ADPKD patients, with a median age of 44 years, estimated glomerular filtration rate of 54.5 mL/min/1.73 m2, and total follow-up duration of 3104 patient-years. Logistic regression analyses were performed to determine factors associated with intracranial aneurysms.

RESULTS

Regarding the presence of intracranial aneurysm, significant interactions were identified between the age category (age ≥ 50 years), female sex (P = 0.0027 for the interaction) and hypertension (P = 0.0074 for the interaction). Female sex and hypertension were associated with intracranial aneurysm risk factors only in patients aged ≥ 50 years. The presence of intracranial aneurysm was significantly associated with chronic kidney disease (CKD) stages 4-5 (odds ratio [OR] = 3.87, P = 0.0007) and family history of intracranial aneurysm or subarachnoid hemorrhage (OR = 2.30, P = 0.0217) in patients aged < 50 years. For patients aged ≥ 50 years, in addition to the abovementioned factors [OR = 2.38, P = 0.0355 for CKD stages 4-5; OR = 3.49, P = 0.0094 for family history of intracranial aneurysm or subarachnoid hemorrhage], female sex (OR = 4.51, P = 0.0005), and hypertension (OR = 5.89, P = 0.0012) were also associated with intracranial aneurysm.

CONCLUSION

Kidney dysfunction and family history of intracranial aneurysm or subarachnoid hemorrhage are risk factors for early-onset intracranial aneurysm. Patients aged < 50 years with a family history of intracranial aneurysm or subarachnoid hemorrhage or with CKD stages 4-5 may be at an increased risk of early-onset intracranial aneurysm.

Deciphering the Impact of Defecation Frequency on Gut Microbiome Composition and Diversity

This study explores the impact of defecation frequency on the gut microbiome structure by analyzing fecal samples from individuals categorized by defecation frequency: infrequent (1-3 times/week, n = 4), mid-frequent (4-6 times/week, n = 7), and frequent (daily, n = 9). Utilizing 16S rRNA gene-based sequencing and LC-MS/MS metabolome profiling, significant differences in microbial diversity and community structures among the groups were observed. The infrequent group showed higher microbial diversity, with community structures significantly varying with defecation frequency, a pattern consistent across all sampling time points. The Ruminococcus genus was predominant in the infrequent group, but decreased with more frequent defecation, while the Bacteroides genus was more common in the frequent group, decreasing as defecation frequency lessened. The infrequent group demonstrated enriched biosynthesis genes for aromatic amino acids and branched-chain amino acids (BCAAs), in contrast to the frequent group, which had a higher prevalence of genes for BCAA catabolism. Metabolome analysis revealed higher levels of metabolites derived from aromatic amino acids and BCAA metabolism in the infrequent group, and lower levels of BCAA-derived metabolites in the frequent group, consistent with their predicted metagenomic functions. These findings underscore the importance of considering stool consistency/frequency in understanding the factors influencing the gut microbiome.

Metabolic Communication by SGLT2 Inhibition

BACKGROUND

SGLT2 (sodium-glucose cotransporter 2) inhibitors (SGLT2i) can protect the kidneys and heart, but the underlying mechanism remains poorly understood.

METHODS

To gain insights on primary effects of SGLT2i that are not confounded by pathophysiologic processes or are secondary to improvement by SGLT2i, we performed an in-depth proteomics, phosphoproteomics, and metabolomics analysis by integrating signatures from multiple metabolic organs and body fluids after 1 week of SGLT2i treatment of nondiabetic as well as diabetic mice with early and uncomplicated hyperglycemia.

RESULTS

Kidneys of nondiabetic mice reacted most strongly to SGLT2i in terms of proteomic reconfiguration, including evidence for less early proximal tubule glucotoxicity and a broad downregulation of the apical uptake transport machinery (including sodium, glucose, urate, purine bases, and amino acids), supported by mouse and human SGLT2 interactome studies. SGLT2i affected heart and liver signaling, but more reactive organs included the white adipose tissue, showing more lipolysis, and, particularly, the gut microbiome, with a lower relative abundance of bacteria taxa capable of fermenting phenylalanine and tryptophan to cardiovascular uremic toxins, resulting in lower plasma levels of these compounds (including p-cresol sulfate). SGLT2i was detectable in murine stool samples and its addition to human stool microbiota fermentation recapitulated some murine microbiome findings, suggesting direct inhibition of fermentation of aromatic amino acids and tryptophan. In mice lacking SGLT2 and in patients with decompensated heart failure or diabetes, the SGLT2i likewise reduced circulating p-cresol sulfate, and p-cresol impaired contractility and rhythm in human induced pluripotent stem cell-derived engineered heart tissue.

CONCLUSIONS

SGLT2i reduced microbiome formation of uremic toxins such as p-cresol sulfate and thereby their body exposure and need for renal detoxification, which, combined with direct kidney effects of SGLT2i, including less proximal tubule glucotoxicity and a broad downregulation of apical transporters (including sodium, amino acid, and urate uptake), provides a metabolic foundation for kidney and cardiovascular protection.

Increased cardiovascular risk in patients with chronic kidney disease

Cardiovascular disease (CVD) is highly prevalent in patients suffering from chronic kidney disease (CKD). The risk of patients with CKD developing CVD is manifested already in the early stages of CKD development. The impact of declined kidney function on increased cardiovascular risk and the underlying mechanisms are complex and multifactorial. This review discusses the impact of (a) traditional cardiovascular risk factors such as smoking, dyslipidemia, diabetes, and hypertension as well as (b) CKD-specific pathophysiological and molecular mechanisms associated with an increased cardiovascular risk. The latter include uremic toxins, post-translational modifications and uremic lipids, innate immune cell activation and inflammation, oxidative stress, endothelial cell dysfunction, increased coagulation and altered platelet responses, vascular calcification, renin-angiotensin-aldosterone-system (RAAS) and sympathetic activation, as well as anemia. Unraveling the complex interplay of different risk factors, especially in the context of patient subcohorts, will help to find new therapeutic approaches in order to reduce the increased cardiovascular risk in this vulnerable patient cohort.

Effect of Hemodialysis with Medium Cut-Off versus High-Flux Membranes on Endothelial Function of Patients with Chronic Kidney Disease

INTRODUCTION

Endothelial dysfunction (ED) is considered a marker of vascular complications, especially in patients with end-stage kidney disease (ESKD). Inflammation and the uremic state contribute to ED in patients undergoing hemodialysis (HD). Recently, the medium cut-off (MCO) dialysis membrane has been proposed to efficiently remove inflammatory cytokines and large, middle-sized uremic toxins, with the potential effect to improve endothelial function. This study aimed to compare the effect of dialysis with MCO or high-flux membranes on the endothelial function of patients on chronic HD.

METHODS

A prospective, randomized, crossover study in which 32 patients with ESKD were dialyzed for 12 weeks with each membrane, including a 4-week washout period between treatments. Endothelial function was assessed by flow-mediated dilation (FMD) using brachial artery ultrasound at weeks 1, 12, 16, and 28.

RESULTS

The population consisted of 59% men, 52.7 ± 13.4 years, 16% non-black, on HD for 8.8 (4.1-15.1) years, and 72% with arteriovenous fistula. Hypertension was the most common etiology of chronic kidney disease, and 34% of patients had previous cardiovascular disease. Patients were grouped, regardless of treatment sequence, into MCO or high-flux groups, since no carryover (p = 0.634) or sequence (p = 0.998) effects were observed in the FMD assessment. The ANOVA model with repeated measures showed no effects of treatment (p = 0.426), time (p = 0.972), or interaction (p = 0.413) in the comparison of FMD between the MCO and high-flux groups.

CONCLUSION

Dialysis performed with MCO, or high-flux membranes, had no influence on endothelial function in patients undergoing HD. However, a trend towards increased FMD was observed with the use of the MCO membrane.

Comprehensive proteomics of monocytes indicates oxidative imbalance functionally related to inflammatory response in chronic kidney disease-related atherosclerosis

Atherosclerosis-induced cardiovascular events are the leading cause of mortality in chronic kidney disease (CKD) patients. Monocytes are involved in the formation of atherosclerotic plaques and mediate in the overproduction of ROS, promoting inflammation and oxidative stress. However, the relationship between monocytes, inflammation, and oxidative status in CKD-associated atherosclerosis has not been thoroughly investigated. Monocytes and plasma derived from two groups of CKD patients with varying degrees of atherosclerosis and two groups of patients with cardiovascular disease (CVD) and non-CKD atherosclerosis were analyzed. This study was designed to perform a comprehensive proteomic analysis of monocytes in combination with functional bioinformatics. In addition, a targeted investigation of oxidative stress- and inflammatory-related factors to explore CKD-associated atherosclerosis was applied. Dysregulation of proteins involved in lipid oxidation, cell survival, ROS synthesis and metabolism, and inflammatory responses has been revealed. The characteristic disturbances in the monocyte proteome changed with the progression of CKD. A closer examination of oxidative stress's triggers, mediators, and effects on protein and lipid levels showed alterations in the oxidative imbalance between CKD and CVD. CKD monocytes demonstrated a significant increase of oxidized glutathione without changing the level of its reduced form. Evaluation of enzymatic antioxidants, sources of ROS, and modifications caused by ROS also revealed significant alterations between the study groups. In CKD, inflammation and oxidative imbalance correlated and drove each other. However, in CVD, oxidative stress-related factors were associated with each other but not to inflammatory proteins. Moreover, lipid abnormalities were more specific to classical CVD and unrelated to CKD. Such a comprehensive characterization of monocytes and oxidative stress in CKD and CVD patients has never been presented so far. Obtained results support the involvement of distinct mechanisms underlying the acceleration of atherosclerotic and non-atherosclerotic CKD.

The role and mechanism of RIPK1 in vascular endothelial dysfunction in chronic kidney disease

Endothelial dysfunction is common in patients with chronic kidney disease (CKD) and cardiovascular events, but the mechanism is unclear. In our study, we found elevated levels of RIPK1 in patients with CKD and cardiovascular events through bioinformation analysis. Elevated RIPK1 levels were found in serum samples of CKD patients and were associated with vascular endothelial dysfunction and renal function. We constructed the five of six nephrectomy of CKD mice model, finding that RIPK1 expressions were elevated in abdominal aorta endothelial cells. After RIPK1 inhibition and overexpression, it was found that RIPK1 could regulate the expression of endothelial nitric oxide synthase (eNOS) and cell adhesion molecule 1 (ICAM-1), and activation of inflammatory responses and endoplasmic reticulum (ER) stress. In addition, uremic toxin induced abnormal expression of RIPK1 in vitro. We observed RIPK1-mediating endothelial dysfunction and inflammation responses by ER stress pathways through gain and loss of function. In order to explore the specific mechanism, we conducted co-immunoprecipitation and expression regulation of RIPK1 and IKK, finding that RIPK1 formed complex with IKK and regulated IKK expression. In conclusion, we demonstrated that RIPK1 levels were closely associated with vascular endothelial dysfunction in patients with CKD. With uremic toxins, RIPK1 expression was elevated, which led to the activation of inflammation through the ER stress pathway, resulting in vascular endothelial injury. Besides, activation of RIPK1-IKK-NF-κB axis was a key driver of endothelial dysfunction in CKD. Our study provides a new perspective for the study of cardiovascular events in CKD.

The functional role of cellular senescence during vascular calcification in chronic kidney disease

Vascular calcification (VC) has emerged as a key predictor of cardiovascular events in patients with chronic kidney disease (CKD). In recent years, an expanding body of research has put forth the concept of accelerated vascular aging among CKD patients, highlighting the significance of vascular cells senescence in the process of VC. Within the milieu of uremia, senescent vascular endothelial cells (VECs) release extracellular microvesicles (MV) that promote vascular smooth muscle cells (VSMCs) senescence, thereby triggering the subsequent osteogenic phenotypic switch and ultimately contributing to the VC process. In addition, senescent vascular progenitor or stem cells with diminished ability to differentiate into VECs and VSMCS, compromise the repair of vascular integrity, on the other hand, release a cascade of molecules associated with senescence, collectively known as the senescence-associated secretory phenotype (SASP), perpetuating the senescence phenomenon. Furthermore, SASP triggers the recruitment of monocytes and macrophages, as well as adjacent VECs and VSMCs into a pro-adhesive and pro-inflammatory senescent state. This pro-inflammatory microenvironment niche not only impacts the functionality of immune cells but also influences the differentiation of myeloid immune cells, thereby amplifying the reduced ability to effectively clear senescent cells of senescent macrophages, promoted calcification of VSMCs. The objective of this paper is to provide a comprehensive review of the contribution of vascular cell senescence to the emergence and advancement of VC. Gaining a comprehensive understanding of the involvement of cellular senescence within the vessel wall is pivotal, especially when it comes to its intersection with VC. This knowledge is essential for advancing groundbreaking anti-aging therapies, aiming to effectively mitigate cardiovascular diseases.

Exercise for chronic kidney disease: effects on vascular and cardiopulmonary function

Patients with chronic kidney disease (CKD) have an exacerbated prevalence of cardiovascular disease (CVD). Vascular dysfunction, characterized by impaired endothelial function and arterial stiffness, and markedly low cardiorespiratory fitness levels are hallmark manifestations of the disease that contribute to the CVD burden. Despite advancements in blood pressure and lipid lowering pharmacological therapies, CVD remains markedly prevalent across the spectrum of CKD. This highlights a stagnation in effective clinical strategies to improve cardiovascular health and reinforces the critical need for adjuvant lifestyle strategies such as physical activity and exercise training to be incorporated into routine clinical care. This narrative review provides an overview of the known effects of exercise on vascular and cardiopulmonary function across the spectrum of CKD. The physiological mechanisms of vascular dysfunction that serve as exercise-specific therapeutic targets are highlighted and future perspectives are discussed.

Sweet, bloody consumption - what we eat and how it affects vascular ageing, the BBB and kidney health in CKD

In today's industrialized society food consumption has changed immensely toward heightened red meat intake and use of artificial sweeteners instead of grains and vegetables or sugar, respectively. These dietary changes affect public health in general through an increased incidence of metabolic diseases like diabetes and obesity, with a further elevated risk for cardiorenal complications. Research shows that high red meat intake and artificial sweeteners ingestion can alter the microbial composition and further intestinal wall barrier permeability allowing increased transmission of uremic toxins like p-cresyl sulfate, indoxyl sulfate, trimethylamine n-oxide and phenylacetylglutamine into the blood stream causing an array of pathophysiological effects especially as a strain on the kidneys, since they are responsible for clearing out the toxins. In this review, we address how the burden of the Western diet affects the gut microbiome in altering the microbial composition and increasing the gut permeability for uremic toxins and the detrimental effects thereof on early vascular aging, the kidney per se and the blood-brain barrier, in addition to the potential implications for dietary changes/interventions to preserve the health issues related to chronic diseases in future.

Metabolomics Assessment of Volume Overload-Induced Heart Failure and Oxidative Stress in the Kidney

The incidence of heart failure (HF) is increasing and is associated with a poor prognosis. Moreover, HF often coexists with renal dysfunction and is associated with a worsened outcome. In many experimental studies on cardiac dysfunction, the function of other organs was either not addressed or did not show any decline. Until now, the exact mechanisms for initiating and sustaining this interaction are still unknown. The objective of this study is to use volume overload to induce cardiac hypertrophy and HF in aortocaval fistula (ACF) rat models, and to elucidate how volume overload affects metabolic changes in the kidney, even with normal renal function, in HF. The results showed the metabolic changes between control and ACF rats, including taurine metabolism; purine metabolism; glycine, serine, and threonine metabolism; glycerophospholipid metabolism; and histidine metabolism. Increasing the downstream purine metabolism from inosine to uric acid in the kidneys of ACF rats induced oxidative stress through xanthine oxidase. This result was consistent with HK-2 cells treated with xanthine and xanthine oxidase. Under oxidative stress, taurine accumulation was observed in ACF rats, indicating increased activity of the hypotaurine-taurine pathway as a defense mechanism against oxidative stress in the kidney. Another antioxidant, ascorbic acid 2-sulfate, showed lower levels in ACF rats, indicating that the kidneys experience elevated oxidative stress due to volume overload and HF. In summary, metabolic profiles are more sensitive than clinical parameters in reacting to damage to the kidney in HF.

Cardiomyopathy in chronic kidney disease: clinical features, biomarkers and the contribution of murine models in understanding pathophysiology

The cardiorenal syndrome (CRS) is described as a multi-organ disease encompassing bidirectionally heart and kidney. In CRS type 4, chronic kidney disease (CKD) leads to cardiac injury. Different pathological mechanisms have been identified to contribute to the establishment of CKD-induced cardiomyopathy, including a neurohormonal dysregulation, disturbances in the mineral metabolism and an accumulation of uremic toxins, playing an important role in the development of inflammation and oxidative stress. Combined, this leads to cardiac dysfunction and cardiac pathophysiological and morphological changes, like left ventricular hypertrophy, myocardial fibrosis and cardiac electrical changes. Given that around 80% of dialysis patients suffer from uremic cardiomyopathy, the study of cardiac outcomes in CKD is clinically highly relevant. The present review summarizes clinical features and biomarkers of CKD-induced cardiomyopathy and discusses underlying pathophysiological mechanisms recently uncovered in the literature. It discloses how animal models have contributed to the understanding of pathological kidney-heart crosstalk, but also provides insights into the variability in observed effects of CKD on the heart in different CKD mouse models, covering both "single hit" as well as "multifactorial hit" models. Overall, this review aims to support research progress in the field of CKD-induced cardiomyopathy.

Leukocyte-endothelial interaction in CKD

Chronic kidney disease (CKD) represents an independent risk factor for cardiovascular diseases (CVD). Accordingly, CKD patients show a substantial increased risk of cardiovascular mortality. Inflammation represents an important link between CKD and CVD. The interaction between endothelial cells and effector cells of the innate immune system plays a central role in the development and progression of inflammation. Vascular injury causes endothelial dysfunction, leading to augmented oxidative stress, increased expression of leukocyte adhesion molecules and chronic inflammation. CKD induces numerous metabolic changes, creating a uremic milieu resulting in the accumulation of various uremic toxins. These toxins lead to vascular injury, endothelial dysfunction and activation of the innate immune system. Recent studies describe CKD-dependent changes in monocytes that promote endothelial dysfunction and thus CKD progression and CKD-associated CVD. The NLR family pyrin domain containing 3-interleukin-1β-interleukin-6 (NLRP3-IL-1β-IL-6) signaling pathway plays a pivotal role in the development and progression of CVD and CKD alike. Several clinical trials are investigating targeted inhibition of this pathway indicating that anti-inflammatory therapeutic strategies may emerge as novel approaches in patients at high cardiovascular risk and nonresolving inflammation. CKD patients in particular would benefit from targeted anti-inflammatory therapy, since conventional therapeutic regimens have limited efficacy in this population.

Prevalence, clinical profile, and risk factors of peripheral artery disease in an Iraqi cohort of chronic kidney disease

Peripheral artery disease (PAD) is prevalent in patients with chronic kidney disease (CKD) and is associated with substantial morbidity, mortality, and a lower quality of life. This study aimed to determine the prevalence of PAD, clinical profile, and related risk factors among patients with CKD in Iraq (a low-to middle-income country). A cross sectional study comprised 175 CKD patients, of them 60% were male, their mean age was 56 ± 12.5 years, attending Nephrology unit, Hawler Teaching Hospital, Erbil, Iraq between march 2022 and November 2022. Data on demographic and baseline characteristics were collected. Laboratory tests were performed. All participants underwent a detailed history and clinical examination. Vascular lesions in the lower limbs were assessed using the ankle-brachial index. PAD was diagnosed based on an ankle-brachial index value ˂ 0.9, relevant symptoms, and clinical findings. Forty-nine patients (28%) had PAD, and only 17 (34.7%) were symptomatic. PAD was significantly associated with older age (P = .008), male sex (P = .039), diabetes (P = .012), and hypertension (P = .023). In addition, PAD prevalence was significantly higher in patients with prior coronary artery disease (P < .001), advanced CKD stages (P .032), low estimated glomerular filtration rate (P .03), albuminuria (P .002), elevated glycated hemoglobin (P .04), and high sensitive C-reactive protein (P < .001). No significant association was detected between PAD and body mass index, smoking, CKD duration, cerebrovascular disease, dyslipidemia, albumin, creatinine, hemoglobin, total PTH, and phosphate. Peripheral artery disease was prevalent in patients with CKD in Iraq, and the most affected patients were asymptomatic. Older age, male sex, hypertension, diabetes, prior coronary artery disease, advanced CKD stages, albuminuria, higher glycated hemoglobin level, and increased high-sensitivity C-reactive protein level were identified as risk factors. Early detection of occult PAD might enhance efforts toward proper prevention and treatment.

Serum Osteoprotegerin Levels and the Vascular Reactivity Index in Patients with Hypertension

Background and Objectives: Osteoprotegerin (OPG), a soluble glycoprotein found in serum, has been associated with both the presence and severity of atherosclerosis. OPG is regarded as the mediator in the process of vascular endothelial dysfunction. Impaired endothelial function has an intimate link with hypertension (HTN) and is associated with significant morbidity and mortality. This study was to investigate the connection between OPG and endothelial dysfunction in patients having HTN. Materials and Methods: There are 102 patients with HTN included. For the purpose of determining the levels of OPG, a commercial enzyme-linked immunosorbent test kit was applied. The vascular reactivity index (VRI), which is assessed via the digital thermal monitoring, provides information on endothelial function. Results: Ten patients with HTN (9.8%) were classified as having poor vascular reactivity (VRI < 1.0), 46 HTN patients (45.1%) as having intermediate vascular reactivity (1.0 ≤ VRI < 2.0), and 46 HTN patients (45.1%) were classified as having high vascular reactivity (VRI ≥ 2.0). A greater serum OPG level (p < 0.001) and older age (p = 0.022) were linked to impaired vascular reactivity. The estimated glomerular filtration rate (r = 0.196, p = 0.048) was positively correlated with VRI values in hypertensive participants, while advanced age (r = -0.222, p = 0.025) and the log-transformed OPG level (log-OPG, r = -0.357, p < 0.001) were negatively correlated with VRI. Serum log-OPG level was shown to be strongly and independently correlated with VRI values in HTN individuals after multivariable forward stepwise linear regression analysis (β = -0.357, adjusted R2 change = 0.119, p < 0.001). Conclusions: In patients with HTN, serum OPG levels were adversely correlated with VRI and probably had a role in endothelial dysfunction.

In-hospital mortality predictors among hospitalized adults and those with chronic kidney disease with dengue

BACKGROUND

Accurately identifying risk factors that predict fatality in dengue is crucial for patient triage and clinical management. Our objective was to identify predictors of death associated with dengue and investigate the clinical characteristics and risk factors among patients with chronic kidney disease (CKD) who died from dengue.

METHODS

A multicenter longitudinal observation study conducted from 2008 to 2019.

RESULTS

A total of 1272 patients (113 who died and 1186 who recovered) diagnosed with dengue were included. Old age, CKD, and an elevated white blood cell count at hospital presentation were identified as independent predictors of in-hospital mortality among individuals infected with the dengue virus. In a subgroup analysis of 138 patients with CKD infected with dengue virus, 64 (46.3%) patients died, with 46 (33.3%) patients dying within 7 days after symptom onset. Among 64 fatal dengue patients with CKD, 34.4% were in stages 2 and 3 of kidney disease, 51.5% were in stages 4 and 5, and 14.1% had end stage renal disease as per the classification by Kidney Disease Improving Global Outcomes. Multivariate analysis revealed that initial altered consciousness, pulmonary edema, and leukocytosis during hospitalization were independently associated with in-hospital mortality in CKD patients infected with the dengue virus. Leukocytosis during hospitalization and severe hepatitis were independent risk factors for death within 7 days after dengue illness onset in CKD patients.

CONCLUSIONS

This study offers valuable insights into predictors linked to fatality in dengue and reinforces the importance of optimizing patient triage to improve the quality of care.

Optical Real-Time Cardiorenal Toxin Uric Acid Measurement During Hemodialysis Using a Miniaturized Optical Sensor

Patients with chronic kidney disease (CKD) are at higher cardiovascular risk than the general population. Cardiovascular diseases, vascular calcification among them, are the leading cause of death in these patients. Factors influencing vascular calcification are oxidative stress, inflammation, and accumulation of uremic toxins during CKD. Uric acid is a cardiorenal toxin that accumulates in the case of kidney malfunction. The primary therapy for replacing kidney function and removing toxins from end-stage renal disease patients is hemodialysis. Effective removal of toxins can be estimated by blood or dialysate lab analysis or optical monitoring. In this study, the authors tested a miniaturized optical sensor for monitoring uric acid levels and removal for the first time in a more extensive clinical study, including Hemodialysis (HD) and Post-dilutional online hemodiafiltration (HDF) procedures with different settings in Tallinn, Estonia. The results (Mean±SD, Lab vs. Sensor) of the uric acid concentration 57.20±34.05 vs. 57.22±33.09 µmol/L, reduction ratio 68.72±10.91 vs. 67.89±12.48 %, and total removed amount 7.00±2.10 vs. 7.33±2.29 mmol did not differ significantly from the values obtained from the clinical laboratory (p<0.05).Clinical Relevance-During this study, a miniaturized optical sensor was tested for the first time in the clinic in different dialysis settings. The results confirm that the sensor is reliable for regularly monitoring cardiorenal toxin uric acid removal during hemodialysis.

Effect of Low Protein Diet Supplemented with Ketoanalogs on Endothelial Function and Protein-Bound Uremic Toxins in Patients with Chronic Kidney Disease

Studies have demonstrated that a low-protein diet supplemented with ketoanalogs (KAs) could significantly retard progression of renal function in patients with chronic kidney disease (CKD) stages 3-5. However, its effects on endothelial function and serum levels of protein-bound uremic toxins remain elusive. Therefore, this study explored whether a low-protein diet (LPD) supplemented with KAs affects kidney function, endothelial function, and serum uremic toxin levels in a CKD-based cohort. In this retrospective cohort, we enrolled 22 stable CKD stage 3b-4 patients on LPD (0.6-0.8 g/day). Patients were categorized into control (LPD only) and study groups (LPD + KAs 6 tab/day). Serum biochemistry, total/free indoxyl sulfate (TIS/FIS), total/free p-cresyl sulfate (TPCS/FPCS), and flow-mediated dilation (FMD) were measured before and after 6 months of KA supplementation. Before the trial, there were no significant differences in kidney function, FMD, or uremic toxin levels between the control and study groups. When compared with the control group, the paired t-test showed a significant decrease in TIS and FIS (all p < 0.05) and a significant increase in FMD, eGFR, and bicarbonate (all p < 0.05). In multivariate regression analysis, an increase in FMD (p < 0.001) and a decrease in FPCS (p = 0.012) and TIS (p < 0.001) remained persistent findings when adjusted for age, systolic blood pressure (SBP), sodium, albumin, and diastolic blood pressure (DBP). LPD supplemented with KAs significantly preserves kidney function and provides additional benefits on endothelial function and protein-bound uremic toxins in patients with CKD.

NETs-Induced Thrombosis Impacts on Cardiovascular and Chronic Kidney Disease

Arterial and venous thrombosis constitute a major source of morbidity and mortality worldwide. Association between thrombotic complications and cardiovascular and other chronic inflammatory diseases are well described. Inflammation and subsequent initiation of thrombotic events, termed immunothrombosis, also receive growing attention but are still incompletely understood. Nevertheless, the clinical relevance of aberrant immunothrombosis, referred to as thromboinflammation, is evident by an increased risk of thrombosis and cardiovascular events in patients with inflammatory or infectious diseases. Proinflammatory mediators released from platelets, complement activation, and the formation of NETs (neutrophil extracellular traps) initiate and foster immunothrombosis. In this review, we highlight and discuss prominent and emerging interrelationships and functions between NETs and other mediators in immunothrombosis in cardiovascular disease. Also, with patients with chronic kidney disease suffering from increased cardiovascular and thrombotic risk, we summarize current knowledge on neutrophil phenotype, function, and NET formation in chronic kidney disease. In addition, we elaborate on therapeutic targeting of NETs-induced immunothrombosis. A better understanding of the functional relevance of antithrombotic mediators which do not increase bleeding risk may provide opportunities for successful therapeutic interventions to reduce thrombotic risk beyond current treatment options.

Endothelial Cell Dysfunction and Increased Cardiovascular Risk in Patients With Chronic Kidney Disease

The endothelium is considered to be the gatekeeper of the vessel wall, maintaining and regulating vascular integrity. In patients with chronic kidney disease, protective endothelial cell functions are impaired due to the proinflammatory, prothrombotic and uremic environment caused by the decline in kidney function, adding to the increase in cardiovascular complications in this vulnerable patient population. In this review, we discuss endothelial cell functioning in healthy conditions and the contribution of endothelial cell dysfunction to cardiovascular disease. Further, we summarize the phenotypic changes of the endothelium in chronic kidney disease patients and the relation of endothelial cell dysfunction to cardiovascular risk in chronic kidney disease. We also review the mechanisms that underlie endothelial changes in chronic kidney disease and consider potential pharmacological interventions that can ameliorate endothelial health.

A Molecular (Not Very Becoming) Picture of Stressed Arteries and Heart, with Some Therapeutic Hope

This Special Issue has focused on molecular mechanisms (vascular calcification, endothelial dysfunction, cardiac remodelling, inflammation, oxidative stress, etc [...].

The Molecular Mechanism and Therapeutic Strategy of Cardiorenal Syndrome Type 3

Cardiorenal syndrome type 3 (CRS3) is defined as acute kidney injury (AKI)-induced acute cardiac dysfunction, characterized by high morbidity and mortality. CRS3 often occurs in elderly patients with AKI who need intensive care. Approximately 70% of AKI patients develop into CRS3. CRS3 may also progress towards chronic kidney disease (CKD) and chronic cardiovascular disease (CVD). However, there is currently no effective treatment. Although the major intermediate factors that can mediate cardiac dysfunction remain elusive, recent studies have summarized the AKI biomarkers, identified direct mechanisms, including mitochondrial dysfunction, inflammation, oxidative stress, apoptosis and activation of the sympathetic nervous system (SNS) and renin-angiotensin-aldosterone system (RAAS), inflammasome, as well as indirect mechanisms such as fluid overload, electrolyte imbalances, acidemia and uremic toxins, which are involved in the pathophysiological changes of CRS3. This study reviews the main pathological characteristics, underlying molecular mechanisms, and potential therapeutic strategies of CRS3. Mitochondrial dysfunction and inflammatory factors have been identified as the key initiators and abnormal links between the impaired heart and kidney, which contribute to the formation of a vicious circle, ultimately accelerating the progression of CRS3. Therefore, targeting mitochondrial dysfunction, antioxidants, Klotho, melatonin, gene therapy, stem cells, exosomes, nanodrugs, intestinal microbiota and Traditional Chinese Medicine may serve as promising therapeutic approaches against CRS3.

Epigallocatechin-3-Gallate Decreases Plasma and Urinary Levels of p-Cresol by Modulating Gut Microbiota in Mice

p-Cresol (PC), a gut bacterial product of tyrosine catabolism, is recognized as a uremic toxin that has negative biological effects. Lowering the plasma PC level by manipulating the gut bacterial composition represents a promising therapeutic strategy in chronic kidney disease. This study was conducted to reveal whether epigallocatechin-3-gallate (EGCG) decreases plasma PC levels by limiting its bacterial production in a mouse model. The PC concentration in the samples was measured by high-performance liquid chromatography (HPLC) after treatments with sulfatase and β-glucuronidase. The results showed that the addition of EGCG to the diet decreased the plasma and urinary concentrations of PC in a dose-dependent manner, with a statistically significant difference between the control group and the 0.2% EGCG group. However, once EGCG was enzymatically hydrolyzed to epigallocatechin (EGC) and gallic acid, such effects were lost almost completely. The addition of 0.2% EGCG in the diet was accompanied by a decreased abundance of Firmicutes at the phylum level and Clostridiales at the order level, which constitute a large part of PC produced from tyrosine. In conclusion, EGCG, not EGC, reduced plasma and urinary concentrations of PC in mice by suppressing its bacterial production with accompanying alteration of the relative abundance of PC producers.

Hypertension in chronic kidney disease: What lies behind the scene

Hypertension is a frequent condition encountered during kidney disease development and a leading cause in its progression. Hallmark factors contributing to hypertension constitute a complexity of events that progress chronic kidney disease (CKD) into end-stage renal disease (ESRD). Multiple crosstalk mechanisms are involved in sustaining the inevitable high blood pressure (BP) state in CKD, and these play an important role in the pathogenesis of increased cardiovascular (CV) events associated with CKD. The present review discusses relevant contributory mechanisms underpinning the promotion of hypertension and their consequent eventuation to renal damage and CV disease. In particular, salt and volume expansion, sympathetic nervous system (SNS) hyperactivity, upregulated renin–angiotensin–aldosterone system (RAAS), oxidative stress, vascular remodeling, endothelial dysfunction, and a range of mediators and signaling molecules which are thought to play a role in this concert of events are emphasized. As the control of high BP via therapeutic interventions can represent the key strategy to not only reduce BP but also the CV burden in kidney disease, evidence for major strategic pathways that can alleviate the progression of hypertensive kidney disease are highlighted. This review provides a particular focus on the impact of RAAS antagonists, renal nerve denervation, baroreflex stimulation, and other modalities affecting BP in the context of CKD, to provide interesting perspectives on the management of hypertensive nephropathy and associated CV comorbidities.

Serum P-Cresyl Sulfate Level Is an Independent Marker of Peripheral Arterial Stiffness as Assessed Using Brachial-Ankle Pulse Wave Velocity in Patients with Non-Dialysis Chronic Kidney Disease Stage 3 to 5

p-Cresyl sulfate (PCS) is a uremic toxin that causes cardiovascular injury and progression in patients with chronic kidney disease (CKD). Peripheral arterial stiffness (PAS) as measured using the brachial-ankle pulse wave velocity (baPWV) is considered a valuable predictor of cardiovascular event risk in the general population. The study investigated the correlation between serum PCS levels and PAS (baPWV > 18.0 m/s) in 160 patients with stage 3−5 CKD. Liquid chromatography−mass spectrometry was used to assay serum PCS levels. PAS was detected in 54 patients (33.8%), and it was linked to older age, a higher prevalence of hypertension, higher systolic and diastolic blood pressure, higher serum calcium−phosphorus product and PCS levels, and lower height and body weight. Multivariable logistic regression analysis for independent factors associated with PAS illustrated that, in addition to age and diastolic blood pressure, serum PCS levels exhibited an odds ratio (OR) of 1.098 (95% confidence interval = 1.029−1.171, p = 0.005). These findings demonstrated that serum PCS levels were associated with PAS among patients with stage 3−5 CKD.