Increased p-cresyl sulfate level is independently associated with poor outcomes in patients with heart failure

Longitudinal Plasma Metabolome Patterns and Relation to Kidney Function and Proteinuria in Pediatric CKD

Key Points

Background

Understanding plasma metabolome patterns in relation to changing kidney function in pediatric CKD is important for continued research for identifying novel biomarkers, characterizing biochemical pathophysiology, and developing targeted interventions. There are a limited number of studies of longitudinal metabolomics and virtually none in pediatric CKD.

Methods

The CKD in Children study is a multi-institutional, prospective cohort that enrolled children aged 6 months to 16 years with eGFR 30–90 ml/min per 1.73 m2. Untargeted metabolomics profiling was performed on plasma samples from the baseline, 2-, and 4-year study visits. There were technologic updates in the metabolomic profiling platform used between the baseline and follow-up assays. Statistical approaches were adopted to avoid direct comparison of baseline and follow-up measurements. To identify metabolite associations with eGFR or urine protein-creatinine ratio (UPCR) among all three time points, we applied linear mixed-effects (LME) models. To identify metabolites associated with time, we applied LME models to the 2- and 4-year follow-up data. We applied linear regression analysis to examine associations between change in metabolite level over time (∆level) and change in eGFR (∆eGFR) and UPCR (∆UPCR). We reported significance on the basis of both the false discovery rate (FDR) <0.05 and P < 0.05.

Results

There were 1156 person-visits (N: baseline=626, 2-year=254, 4-year=276) included. There were 622 metabolites with standardized measurements at all three time points. In LME modeling, 406 and 343 metabolites associated with eGFR and UPCR at FDR <0.05, respectively. Among 530 follow-up person-visits, 158 metabolites showed differences over time at FDR <0.05. For participants with complete data at both follow-up visits (n=123), we report 35 metabolites with ∆level–∆eGFR associations significant at FDR <0.05. There were no metabolites with significant ∆level–∆UPCR associations at FDR <0.05. We report 16 metabolites with ∆level–∆UPCR associations at P < 0.05 and associations with UPCR in LME modeling at FDR <0.05.

Conclusions

We characterized longitudinal plasma metabolomic patterns associated with eGFR and UPCR in a large pediatric CKD population. Many of these metabolite signals have been associated with CKD progression, etiology, and proteinuria in previous CKD Biomarkers Consortium studies. There were also novel metabolite associations with eGFR and proteinuria detected.

Metabolomics and Cardiovascular Risk in Patients with Heart Failure: A Systematic Review and Meta-Analysis

The associations of plasma metabolites with adverse cardiovascular (CV) outcomes are still underexplored and may be useful in CV risk stratification. We performed a systematic review and meta-analysis to establish correlations between blood metabolites and adverse CV outcomes in patients with heart failure (HF). Four cohorts were included, involving 83 metabolites and 37 metabolite ratios, measured in 1158 HF patients. Hazard ratios (HR) of 42 metabolites and 3 metabolite ratios, present in at least two studies, were combined through meta-analysis. Higher levels of histidine (HR 0.74, 95% CI [0.64; 0.86]) and tryptophan (HR 0.82 [0.71; 0.96]) seemed protective, whereas higher levels of symmetric dimethylarginine (SDMA) (HR 1.58 [1.30; 1.93]), N-methyl-1-histidine (HR 1.56 [1.27; 1.90]), SDMA/arginine (HR 1.38 [1.14; 1.68]), putrescine (HR 1.31 [1.06; 1.61]), methionine sulfoxide (HR 1.26 [1.03; 1.52]), and 5-hydroxylysine (HR 1.25 [1.05; 1.48]) were associated with a higher risk of CV events. Our findings corroborate important associations between metabolic imbalances and a higher risk of CV events in HF patients. However, the lack of standardization and data reporting hampered the comparison of a higher number of studies. In a future clinical scenario, metabolomics will greatly benefit from harmonizing sample handling, data analysis, reporting, and sharing.

Circulating Metabolomic Associations with Neurocognitive Outcomes in Pediatric CKD

BACKGROUND

Children with CKD are at risk for impaired neurocognitive functioning. We investigated metabolomic associations with neurocognition in children with CKD.

METHODS

We leveraged data from the Chronic Kidney Disease in Children (CKiD) study and the Neurocognitive Assessment and Magnetic Resonance Imaging Analysis of Children and Young Adults with Chronic Kidney Disease (NiCK) study. CKiD is a multi-institutional cohort that enrolled children aged 6 months to 16 years with eGFR 30-90 ml/min per 1.73 m 2 ( n =569). NiCK is a single-center cross-sectional study of participants aged 8-25 years with eGFR<90 ml/min per 1.73 m 2 ( n =60) and matched healthy controls ( n =67). Untargeted metabolomic quantification was performed on plasma (CKiD, 622 metabolites) and serum (NiCK, 825 metabolites) samples. Four neurocognitive domains were assessed: intelligence, attention regulation, working memory, and parent ratings of executive function. Repeat assessments were performed in CKiD at 2-year intervals. Linear regression and linear mixed-effects regression analyses adjusting for age, sex, delivery history, hypertension, proteinuria, CKD duration, and glomerular versus nonglomerular diagnosis were used to identify metabolites associated with neurocognitive z-scores. Analyses were performed with and without adjustment for eGFR.

RESULTS

There were multiple metabolite associations with neurocognition observed in at least two of the analytic samples (CKiD baseline, CKiD follow-up, and NiCK CKD). Most of these metabolites were significantly elevated in children with CKD compared with healthy controls in NiCK. Notable signals included associations with parental ratings of executive function: phenylacetylglutamine, indoleacetylglutamine, and trimethylamine N-oxide-and with intelligence: γ -glutamyl amino acids and aconitate.

CONCLUSIONS

Several metabolites were associated with neurocognitive dysfunction in pediatric CKD, implicating gut microbiome-derived substances, mitochondrial dysfunction, and altered energy metabolism, circulating toxins, and redox homeostasis.

Gut microbiome supplementation as therapy for metabolic syndrome

The gut microbiome is defined as an ecological community of commensal symbiotic and pathogenic microorganisms that exist in our body. Gut microbiome dysbiosis is a condition of dysregulated and disrupted intestinal bacterial homeostasis, and recent evidence has shown that dysbiosis is related to chronic inflammation, insulin resistance, cardiovascular diseases (CVD), type 2 diabetes mellitus (T2DM), and obesity. It is well known that obesity, T2DM and CVD are caused or worsened by multiple factors like genetic predisposition, environmental factors, unhealthy high calorie diets, and sedentary lifestyle. However, recent evidence from human and mouse models suggest that the gut microbiome is also an active player in the modulation of metabolic syndrome, a set of risk factors including obesity, hyperglycemia, and dyslipidemia that increase the risk for CVD, T2DM, and other diseases. Current research aims to identify treatments to increase the number of beneficial microbiota in the gut microbiome in order to modulate metabolic syndrome by reducing chronic inflammation and insulin resistance. There is increasing interest in supplements, classified as prebiotics, probiotics, synbiotics, or postbiotics, and their effect on the gut microbiome and metabolic syndrome. In this review article, we have summarized current research on these supplements that are available to improve the abundance of beneficial gut microbiota and to reduce the harmful ones in patients with metabolic syndrome.

Oral administration of vancomycin alleviates heart failure triggered by chronic kidney disease

Chronic kidney disease (CKD) induces an imbalance in the intestinal microbiota, affecting various physiological functions and leading to cardiovascular inflammation and fibrosis. However, the cardiotoxic impact of intestinal microbiota-derived uremic substances in advanced renal dysfunction remains unexplored. Therefore, we developed a 5/6 nephrectomy (5/6Nx) mouse model to investigate the intestinal microbiota and the effects of administering vancomycin (VCM) on the microbiota and the cardiac pathology associated with CKD. Despite VCM administration after the development of irreversible glomerulosclerosis and tubulointerstitial fibrosis, blood indoxyl sulfate and phenyl sulfate levels, which are intestinal bacteria-derived uremic substances, brain natriuretic peptide levels, and the fibrotic area in the heart were decreased. Moreover, VCM administration prevented 5/6Nx-induced weight loss and prolonged survival time. Our findings suggest that VCM-induced changes in the intestinal microbiota composition ameliorate heart failure and improve survival rates by reducing intestinal microbiota-derived cardiotoxic substances despite advanced renal dysfunction. This highlights the potential of using the intestinal microbiota as a target to prevent and treat cardiovascular conditions associated with CKD.

The Effects of Increasing Dietary Fat on Serum Lipid Profile and Modification of Gut Microbiome in C57BL/6N Mice

Hyperlipidemia is a condition where the blood shows an elevated level of lipid, such as cholesterol and triglyceride. It is considered a risk factor for all coronary artery death globally. Association of microbiome with non-communicable diseases (NCDs) including hyperlipidemia has been reportedly associated. In this study, we hypothesize that the change in microbiome is correlated to the change in serum lipid level, which resulted by increasing dietary fat consumption. The 32 male, 14-week-old, C57BL/6N were divided into 4 groups, each group received control diet, 10%, 20%, and 40% kcal fat diet prepared from purified pork lard, respectively for 28 days. Fasting serum lipids and fecal microbiome were then analyzed. The group of animals assigned to 40% kcal fat showed significantly increased serum cholesterol, LDL, and HDL (p < 0.05). Microbiome analysis revealed the abundance of Muribaculaceae and Saccharimonadaceae were significantly decreased (p < 0.05). On the contrary, the abundance of Clostridia_UCG014, Akkermansiaceae, Bacteroidaceae, Oscillospiraceae, and Erysipelotrichaceae were significantly increased (p < 0.05). Spearman correlation indicated that the abundance of Akkermansiaceae and Bacteroidaceae were positively associated with the increased of serum cholesterol and LDL (p < 0.05), while the abundance of Muribaculaceae, Clostridia_UCG-014, and Saccharimonadaceae were negatively associated (p < 0.05). These results suggest that dietary fat have ability to manipulated microbiome with relative to elevation of serum lipid profile.

Gut Microbiota-Derived Metabolites and Cardiovascular Disease Risk: A Systematic Review of Prospective Cohort Studies

Gut microbiota-derived metabolites have recently attracted considerable attention due to their role in host-microbial crosstalk and their link with cardiovascular health. The MEDLINE-PubMed and Elsevier’s Scopus databases were searched up to June 2022 for studies evaluating the association of baseline circulating levels of trimethylamine N-oxide (TMAO), secondary bile acids, short-chain fatty acids (SCFAs), branched-chain amino acids (BCAAs), tryptophan and indole derivatives, with risk of cardiovascular disease (CVD). A total of twenty-one studies were included in the systematic review after evaluating 1210 non-duplicate records. There were nineteen of the twenty-one studies that were cohort studies and two studies had a nested case–control design. All of the included studies were of high quality according to the “Newcastle–Ottawa Scale”. TMAO was positively associated with adverse cardiovascular events and CVD/all-cause mortality in some, but not all of the included studies. Bile acids were associated with atrial fibrillation and CVD/all-cause mortality, but not with CVD. Positive associations were found between BCAAs and CVD, and between indole derivatives and major adverse cardiovascular events, while a negative association was reported between tryptophan and all-cause mortality. No studies examining the relationship between SCFAs and CVD risk were identified. Evidence from prospective studies included in the systematic review supports a role of microbial metabolites in CVD.

Does the gut microbiome mediate antipsychotic-induced metabolic side effects in schizophrenia?

INTRODUCTION

Second-generation antipsychotics (SGAs) are the most effective treatment for people with schizophrenia. Despite their effectiveness in treating psychotic symptoms, they have been linked to metabolic, cardiovascular and gastrointestinal side-effects. The gut microbiome has been implicated in potentiating symptoms of schizophrenia, response to treatment and medication-induced side effects and thus presents a novel target mediating second-generation antipsychotic-induced side effects in patients.

AREAS COVERED

This narrative review presents evidence from clinical and pre-clinical studies exploring the relationship between the gut microbiome, schizophrenia, second-generation antipsychotics and antipsychotic-induced side-effects. It also covers evidence for psychobiotic treatment as a potential supplementary therapy for people with schizophrenia.

EXPERT OPINION

The gut microbiome has the potential to mediate antipsychotic-induced side-effects in people with schizophrenia. Microbiome-focused treatments should be considered in combination with standard therapy in order to ameliorate debilitating drug-induced side effects, increase quality of life and potentially improve psychotic symptoms. Future studies should aim to collect not only microbiome data, but also metabolomic measures, dietary information and behavioral data.

p-Cresyl Sulfate Predicts Ischemic Stroke among Patients on Hemodialysis: A Prospective Cohort Study

Background and Purpose. Hemodialysis patients face a higher risk of ischemic stroke. p-Cresyl sulfate is a typical protein-bound uremic toxin that contributes to chronic kidney disease and cardiovascular disease progression, as well as mortality in hemodialysis patients. The present study was aimed at elucidating the association between p-cresyl sulfate and the risk of ischemic stroke in hemodialysis patients. Method. Patients on hemodialysis over 6 months were enrolled in this prospective cohort study and were divided into 2 groups based on plasma p-cresyl sulfate level. The primary end point was the first episode of ischemic stroke during follow-up. The association between p-cresyl sulfate and ischemic stroke incidence was analyzed by Kaplan-Meier method and Cox proportional hazard model. Results. 220 patients were enrolled in this study. 44 patients experienced episodes of first ischemic stroke during follow-up for 87.8 (47.6-119.5) months. Kaplan-Meier analysis demonstrated that the incidence of ischemic stroke in the high p-cresyl sulfate group was significantly higher than that in the low p-cresyl sulfate group (Log-Rank $P=0.007$ ). Cox regression analysis as well proved that p-cresyl sulfate level was significantly associated with the first incidence of ischemic stroke (HR (hazard ratio) 2.332, 95% CI (95% confidence interval) 1.236-4.399, $P=0.009$ ). After being adjusted for other confounding risk factors, the results persisted significant (model 11: HR 2.061, 95% CI 1.030-4.125, $P=0.041$ ). Conclusion. Plasma p-cresyl sulfate predicts the first incidence of ischemic stroke in hemodialysis patients.

Gut microbiome and cardiovascular disease

PURPOSE OF REVIEW

This review aims to highlight the association between gut microbiome and cardiovascular disease (CVD) with emphasis on the possible molecular mechanisms by which how gut microbiome contributes to CVD.

RECENT FINDINGS

Increasingly, the roles of gut microbiome in cardiovascular health and disease have gained much attention. Most of the investigations focus on how the gut dysbiosis contributes to CVD risk factors and which gut microbial-derived metabolites mediate such effects.

SUMMARY

In this review, we discuss the molecular mechanisms of gut microbiome contributing to CVD, which include gut microbes translocalization to aortic artery because of gut barrier defect to initiate inflammation and microbial-derived metabolites inducing inflammation-signaling pathway and renal insufficiency. Specifically, we categorize beneficial and deleterious microbial-derived metabolites in cardiovascular health. We also summarize recent findings in the gut microbiome modulation of drug efficacy in treatment of CVD and the microbiome mechanisms by which how physical exercise ameliorates cardiovascular health. Gut microbiome has become an essential component of cardiovascular research and a crucial consideration factor in cardiovascular health and disease.

Decreases in Circulating Concentrations of Short-Chain Acylcarnitines are Associated with Systolic Function Improvement After Decompensated Heart Failure

Impaired fatty acid metabolism is associated with heart failure (HF) prognosis. However, specific changes in acylcarnitine profiles and their potential clinical value have not been well explored in patients recovering from acute decompensation.This study recruited 79 HF patients hospitalized because of acute decompensation with a left ventricular ejection fraction (LVEF) of < 40% and 51 normal controls. Patients were dichotomized into two groups, namely, the "improved (IMP) " and the "non-improved (NIMP) " groups, as defined by the changes in LVEF from baseline to 12 months after discharge. Mass spectrometry was used to quantify the acylcarnitine concentrations at baseline and 6 and 12 months after discharge. The IMP and NIMP groups contained 42 and 37 patients, respectively. At baseline, HF patients had higher plasma concentrations of specific long-, medium-, and short-chain acylcarnitines compared to normal controls. From baseline to 12 months post-discharge, the IMP group showed significant decreases in long- and short-chain acylcarnitine concentrations, but significant increases in medium-chain acylcarnitines. In the NIMP group, none of the acylcarnitines significantly decreased, and significant increases were noted in long-, medium-, and short-chain acylcarnitines. Generalized estimating equations demonstrated that nine acylcarnitines could discriminate the IMP group from the NIMP group, including three long-chain (C18:1, C16, and C16:1) and six short-chain acylcarnitines (C5, C5-OH, C4, C4:1-DC, C3, and C2). After adjusting for age, the six short-chain acylcarnitines remained significant. Changes in short-chain acylcarnitine profiles are independently associated with the improvement in cardiac systolic function after acute decompensation.

Metabolomics Research Conducted by Nurse Scientists: A Systematic Scoping Review

Metabolomics, one of the newest omics, allows for investigation of holistic responses of living systems to myriad biological, behavioral, and environmental factors. Researcher use metabolomics to examine the underlying mechanisms of clinically observed phenotypes. However, these methods are complex, potentially impeding their uptake by scientists. In this scoping review, we summarize literature illustrating nurse scientists' use of metabolomics. Using electronic search methods, we identified metabolomics investigations conducted by nurse scientists and published in English-language journals between 1990 and November 2019. Of the studies included in the review (N = 30), 9 (30%) listed first and/or senior authors that were nurses. Studies were conducted predominantly in the United States and focused on a wide array of clinical conditions across the life span. The upward trend we note in the use of these methods by nurse scientists over the past 2 decades mirrors a similar trend across scientists of all backgrounds. A broad range of study designs were represented in the literature we reviewed, with the majority involving untargeted metabolomics (n = 16, 53.3%) used to generate hypotheses (n = 13, 76.7%) of potential metabolites and/or metabolic pathways as mechanisms of clinical conditions. Metabolomics methods match well with the unique perspective of nurse researchers, who seek to integrate the experiences of individuals to develop a scientific basis for clinical practice that emphasizes personalized approaches. Although small in number, metabolomics investigations by nurse scientists can serve as the foundation for robust programs of research to answer essential questions for nursing.

Prognostic Value of Asymmetric Dimethylarginine in Patients with Heart Failure: A Systematic Review and Meta-analysis

Objective

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis, is reported to be a risk factor for cardiovascular disease. The purpose of the present study is to investigate whether ADMA is an independent predictor for future mortality and adverse clinical events among patients with heart failure (HF).

Methods

Electronic literature databases (Central, MEDLINE, and Embase) were searched for relevant observational studies on the prognostic value of ADMA in HF patients published before January 2019. Pooled hazard ratios (HRs) or odds ratio and the corresponding 95% confidence interval (CI) were calculated for risk evaluation.

Results

10 studies with 2195 participants were identified and analyzed. The pooled HR of composite clinical events for the highest vs. lowest quartiles from categorical variable results was 1.34 (95% CI: 1.15-1.57, P < 0.001, I² = 0%), which is 1.31 (95% CI: 1.10-1.55, P < 0.005, I² = 0%) in the subgroup of acute decompensated HF. The pooled HR of composite clinical events from continuous variable results was 1.41 (95% CI: 1.21-1.63, P < 0.001, I² = 21.9%), with 0.1 μM increment accounting for the increasing 25% risk for composite adverse clinical events. The pooled HR for all-cause mortality was 2.38 (95% CI: 1.48-3.82, P < 0.001, I² = 0%) after sensitivity analysis. Two studies reporting the HR of inhospital mortality in HF patients regarded it as a prognostic indicator, with categorical variable HR as 1.26 (95% CI: 1.07-1.84, P < 0.05) and continuous variable OR as 2.15 (95% CI: 1.17–4.29, P < 0.05).

Conclusions

ADMA is an independent predictor for composite clinical outcomes among HF patients with both short-term and long-term prognostic value.

Applying mass spectrometry-based assays to explore gut microbial metabolism and associations with disease

The workings of the gut microbiome have gained increasing interest in recent years through the mounting evidence that the microbiota plays an influential role in human health and disease. A principal focus of this research seeks to further understand the production of metabolic by-products produced by bacteria resident in the gut, and the subsequent interaction of these metabolites on host physiology and pathophysiology of disease. Gut bacterial metabolites of interest are predominately formed via metabolic breakdown of dietary compounds including choline and ʟ-carnitine (trimethylamine N-oxide), amino acids (phenol- and indole-containing uremic toxins) and non-digestible dietary fibers (short-chain fatty acids). Investigations have been accelerated through the application of mass spectrometry (MS)-based assays to quantitatively assess the concentration of these metabolites in laboratory- and animal-based experiments, as well as for direct circulating measurements in clinical research populations. This review seeks to explore the impact of these metabolites on disease, as well as to introduce the application of MS for those less accustomed to its use as a clinical tool, highlighting pertinent research related to its use for measurements of gut bacteria-mediated metabolites to further understand their associations with disease.

Elevated intracellular copper contributes a unique role to kidney fibrosis by lysyl oxidase mediated matrix crosslinking

Copper ions play various roles in mammalian cells, presumably due to their involvement in different enzymatic reactions. Some studies indicated that serum copper correlates with fibrosis in organs, such as liver and lung. However, the mechanism is unknown. Here, we explored the role of copper in kidney fibrosis development and possible underlying mechanisms. We found that copper transporter 1 (CTR1) expression was increased in the kidney tissues in two fibrosis models and in patients with kidney fibrosis. Similar results were also found in renal tubular epithelial cells and fibroblast cells treated with transforming growth factor beta (TGF-β). Mechanistically, the upregulation of CTR1 required Smads-dependent TGF-β signaling pathway and Smad3 directly binded to the promoter of CTR1 in renal fibroblast cells using chromatin immunoprecipitation. Elevated CTR1 induced increase of copper intracellular influx. The elevated intracellular copper ions activated lysyl oxidase (LOX) to enhance the crosslinking of collagen and elastin, which then promoted kidney fibrosis. Reducing intracellular copper accumulation by knocking down CTR1 ameliorated kidney fibrosis in unilateral ureteral obstruction induced renal fibrosis model and renal fibroblast cells stimulated by TGF-β. Treatment with copper chelator tetrathiomolybdate (TM) also alleviated renal fibrosis in vivo and in vitro. In conclusion, intracellular copper accumulation plays a unique role to kidney fibrosis by activating LOX mediated collagen and elastin crosslinking. Inhibition of intracellular copper overload may be a potential portal to alleviate kidney fibrosis.

Unambiguous Characterization of p-Cresyl Sulfate, a Protein-Bound Uremic Toxin, as Biomarker of Heart and Kidney Disease

p-Cresyl sulfate is one of the bound uremic toxins whose level increases in the sera of patients with the severity of chronic kidney disease and is therefore used as a standard for clinical investigations. Our first attempts to obtain p-cresyl sulfate led exclusively to the product of sulfonation of the aromatic ring instead of sulfation on the OH moiety. Nevertheless, this initial discouraging result allowed us to handle both p-cresyl sulfate and 2-hydroxy-5-methylbenzenesulfonic acid obtained by different synthetic pathways. Interestingly, the comparison between the two isomers pointed out that the two molecules show the same fragmentation pattern and are indistinguishable by mass spectrometry. They cannot be separated on several commercially available columns. The only difference between the two compounds is a 10-fold higher ionization yield under negative ion electrospray ionization. NMR spectral studies definitely confirmed the different molecular structures. We present here an unambiguous biomimetic synthetic route for p-cresyl sulfate and the spectroscopic characterization of both the compounds by nuclear magnetic resonance and mass spectrometry.

Amino Acid-Based Metabolic Profile Provides Functional Assessment and Prognostic Value for Heart Failure Outpatients

Functional capacity is a crucial parameter correlated with outcomes. The currently used New York Heart Association functional classification (NYHA Fc) system has substantial limitations, leading to inaccurate classification. This study investigated whether amino acid-based assessment on metabolic status provides an objective way to assess functional capacity and prognosis in heart failure (HF) outpatients. Plasma concentrations of histidine, ornithine, and phenylalanine (HOP) were measured on 890 HF outpatients to assess metabolic status by calculating the HOP score. Cardiopulmonary exercise testing (CPET) was performed in 387 patients to measure metabolic equivalents (MET) in order to define the functional class based on MET (MET Fc). Patients were followed for composite events (death/HF-related rehospitalization) up to one year. We found only 47% concordance between the MET Fc and NYHA Fc. HOP scores worked better than NYHA Fc for discriminating patients with MET Fc II and III from those with MET Fc I, with the optimal cutoff value set at 8.8. HOP scores ≥ 8.8 were associated with risk factors for composite events in different kinds of HF populations and were a powerful predictor of composite events in univariate analysis. In multivariable analysis, HOP scores ≥ 8.8 remained a powerful event predictor, independent of other risk factors. Kaplan-Meier curves revealed that HOP scores of ≥8.8 stratified patients at higher risk of composite events in a variety of HF populations. In conclusion, amino acid-based assessment of metabolic status correlates with functional capacity in HF outpatients and provides prognostic value for a variety of HF populations.

Urinary Excretion of Sulfur Metabolites and Risk of Cardiovascular Events and All-Cause Mortality in the General Population

Aims: Thiosulfate and sulfate are metabolites of hydrogen sulfide (H₂S), a gaseous signaling molecule with cardiovascular (CV) protective properties. Urinary thiosulfate excretion and sulfate excretion are associated with favorable disease outcome in high-risk patient groups. We investigated the relationship between urinary excretion of sulfur metabolites, and risk of CV events and all-cause mortality in the general population. Results: Subjects (n = 6839) of the Prevention of Renal and Vascular End-stage Disease (PREVEND) study were followed prospectively. At baseline, 24-h urinary excretion of thiosulfate and sulfate was determined. Median urinary thiosulfate and sulfate excretion values were 1.27 (interquartile range [IQR] 0.89-2.37) μmol/24 h and 15.7 (IQR 12.0-20.3) mmol/24 h, respectively. Neither thiosulfate nor sulfate excretion showed an independent association with risk of CV events. Sulfate, but not thiosulfate, was inversely associated with risk of all-cause mortality, independent of potential confounders (hazard ratio 0.73 [95% confidence interval 0.63-0.84], p < 0.001). This association appeared most pronounced for normolipidemic subjects (p_interaction = 0.019). Innovation: The strong association between sulfate excretion and mortality in the general population emphasizes the (patho)physiological importance of sulfate or its precursor H₂S. Conclusion: We hypothesize that urinary sulfate excretion, which is inversely associated with all-cause mortality in the general population, holds clinical relevance as a beneficial modulator in health and disease. Antioxid. Redox Signal. 30, 1999-2010.

Phenylalanine- and leucine-defined metabolic types identify high mortality risk in patients with severe infection

OBJECTIVE

To investigate the prognostic value of phenylalanine and leucine in patients with severe infection.

METHODS

Ninety-three patients with infection who had a quick Sequential Organ Failure Assessment (qSOFA) score ≥2 were enrolled. Plasma phenylalanine, leucine, albumin, C-reactive protein, pre-albumin, and transferrin were measured and the SOFA score at enrollment was calculated after hospitalization.

RESULTS

During the 3-month follow-up, 30 (32.3%) patients died. Death was associated with higher SOFA scores, a higher incidence of bacteremia and admission to the intensive care unit, higher C-reactive protein and phenylalanine levels, worse kidney function, and lower pre-albumin and transferrin levels. Patients were categorized into three groups: high-risk type 1 (phenylalanine ≥84μM), high-risk type 2 (phenylalanine <84μM and leucine <93μM), and low-risk (other). Compared to the low-risk type patients, high-risk type 1 and 2 patients had higher mortality rates (hazard ratio 10.1 (95% CI 2.33-43.5) and hazard ratio 5.56 (95% CI 1.22-25.4), respectively). Type 1 patients had higher SOFA scores, a higher incidence of admission to the intensive care unit, and higher C-reactive protein and leucine levels. Type 2 patients had lower albumin and hemoglobin levels. Multivariable analysis showed that both high-risk types were independent predictors of death.

CONCLUSIONS

Phenylalanine- and leucine-defined risk classifications provide metabolic information with prognostic value for patients with severe infection.

Lipidomics reveals accumulation of the oxidized cholesterol in erythrocytes of heart failure patients

Lipids play an important role in the pathogenesis of cardiovascular disease. Changes in lipids of erythrocytes are indicative of the outcome of pathophysiological processes. In the present study, we assessed whether the lipid profiles of erythrocytes from heart failure (HF) patients are informative of their disease risk. The lipidomes of erythrocytes from 10 control subjects and 29 patients at different HF stages were analyzed using liquid chromatography time-of-flight mass spectrometry. The lipid composition of erythrocytes obtained from HF patients was significantly different from that of normal controls. The levels of phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), and sphingomyelins decreased in HF erythrocytes as compared with those of control subjects; however, the levels of lysoPCs, lysoPEs, and ceramides increased in HF erythrocytes. Notably, the oxidized cholesterol 7-ketocholesterol (7KCh) accumulated to higher level in HF erythrocytes than in plasma from the same patients. We further validated our findings with a cohort of 115 subjects of control subjects (n=28) and patients (n=87). Mechanistically, 7KCh promoted reactive oxygen species (ROS) formation in cardiomyocytes; and induced their death, probably through an ATF4-dependent pathway. Our findings suggest that erythrocytic 7KCh can be a risk factor for HF, and is probably implicated in its pathophysiology.

The fate of sulfate in chronic heart failure

New leads to advance our understanding of heart failure (HF) pathophysiology are urgently needed. Previous studies have linked urinary sulfate excretion to a favorable cardiovascular risk profile. Sulfate is not only the end product of hydrogen sulfide metabolism but is also directly involved in various (patho)physiological processes, provoking scientific interest in its renal handling. This study investigates sulfate clearance in chronic HF (CHF) patients and healthy individuals and considers its relationship with disease outcome. Parameters related to renal sulfate handling were determined in and compared between 96 previously characterized CHF patients and sex-matched healthy individuals. Among patients, sulfate clearance was analyzed for associations with clinical and outcome parameters. In CHF patients, plasma sulfate concentrations are significantly higher, whereas 24-h urinary excretion, fractional excretion, and clearance of sulfate are significantly lower, compared with healthy individuals. Among patients, sulfate clearance is independently associated with diuretics use, creatinine clearance and 24-h urinary sodium excretion. Sulfate clearance is associated with favorable disease outcome [hazard ratio per SD increase 0.38 (95% confidence interval 0.23-0.63), P < 0.001]. Although significance was lost after adjustment for creatinine clearance, the decrease of sulfate clearance in patients is independent of this parameter, indicating that sulfate clearance is not merely a reflection of renal function. This exploratory study reveals aberrant sulfate clearance as a potential contributor to CHF pathophysiology, with reduced levels in patients and a positive association with favorable disease outcome. Further research is needed to unravel the nature of its involvement and to determine its potential as a biomarker and target for therapy.NEW & NOTEWORTHY Sulfate clearance is decreased in chronic heart failure patients compared with healthy individuals. Among patients, sulfate clearance is positively associated with favorable disease outcome, i.e., a decreased rehospitalization rate and increased patient survival. Hence, decreased sulfate clearance may be involved in the pathophysiology of heart failure.

Untargeted plasma and tissue metabolomics in rats with chronic kidney disease given AST-120

Chronic kidney disease (CKD) results in the accumulation of metabolic waste products that are normally cleared by the kidney, known as uremia. Many of these waste products are from bacteria metabolites in the gut. Accumulation of uremic toxins in plasma and tissue, as well as the gut-plasma-tissue metabolic axis are important for understanding pathophysiological mechanisms of comorbidities in CKD. In this study, an untargeted metabolomics approach was used to determine uremic toxin accumulation in plasma, liver, heart and kidney tissue in rats with adenine-induced CKD. Rats with CKD were also given AST-120, a spherical carbon adsorbent, to assess metabolic changes in plasma and tissues with the removal of gut-derived uremic toxins. AST-120 decreased >55% of metabolites that were increased in plasma, liver and heart tissue of rats with CKD. CKD was primarily defined by 8 gut-derived uremic toxins, which were significantly increased in plasma and all tissues. These metabolites were derived from aromatic amino acids and soy protein including: indoxyl sulfate, p-cresyl sulfate, hippuric acid, phenyl sulfate, pyrocatechol sulfate, 4-ethylphenyl sulfate, p-cresol glucuronide and equol 7-glucuronide. Our results highlight the importance of diet and gut-derived metabolites in the accumulation of uremic toxins and define the gut-plasma-tissue metabolic axis in CKD.