The metabolic signature of cardiovascular disease and arterial calcification in patients with chronic kidney disease

Serum tryptophan and kynurenine levels and risk of heart failure among patients with chronic kidney disease

BACKGROUND AND AIMS

Chronic kidney disease (CKD) is often complicated by heart failure (HF), leading to increased mortality. Emerging evidence suggests that Tryptophan metabolites, through the Kynurenine pathway (KP), play a significant role in HF pathophysiology. Therefore, we explored the association of Tryptophan (TRP), Kynurenine (KYN), and the Kynurenine to Tryptophan ratio (KTR) with HF in CKD, hypothesizing a link between KP alterations and HF occurrence in this population.

METHODS

673 non-dialysis patients aged 30 to 75 with CKD stages 1-5 were included. Incident HF data were collected through medical record reviews, and the median follow-up time was 3.9 years. Serum concentrations of KYN and TRP were measured using High-Performance Liquid Chromatography (HPLC).

RESULTS

Patients with more advanced stages of CKD had higher levels of KYN and KTR, and lower levels of TRP (p < 0.001). Following adjustments for age, sex, BMI, hypertension, and hypercholesterolemia, serum KYN and KTR remained significantly associated with prevalent HF in patients with CKD (p = 0.012, p = 0.028 respectively). Furthermore, Cox-regression analysis indicated that KTR concentration was associated with incident HF after adjusting for confounders such as age, sex, BMI, hypertension, hypercholesterolemia and diabetes (p = 0.019).

CONCLUSION

In conclusion, the present analysis suggests that changes in the kynurenine pathway may be a new biomarker for HF in patients with CKD. Thus, KTR concentration might be associated with prevalent and future HF in patients with CKD. Further research is needed to understand the mechanisms and potential of these metabolites in refining HF risk prediction and prevention in CKD patients.

Association of Small HDL Subclasses with Mortality Risk in Chronic Kidney Disease

High-density lipoproteins (HDL) exist in various subclasses, with smaller HDL particles possessing the highest anti-oxidative and anti-inflammatory properties. Understanding the role of these specific subclasses in chronic kidney disease (CKD) could provide valuable insights into disease progression and potential therapeutic targets. In the present study, we assessed HDL subclass composition in 463 patients with CKD stage 2-4 using nuclear magnetic resonance spectroscopy. Over a mean follow-up period of 5.0 years, 18.6% of patients died. Compared to survivors, deceased patients exhibited significantly lower levels of cholesterol, ApoA-I, and ApoA-II within the small and extra-small (XS) HDL subclasses. Multivariable Cox regression analysis, adjusted for traditional cardiovascular and renal risk factors, demonstrated that reduced levels of XS-HDL-cholesterol, XS-HDL-ApoA-I, and XS-HDL-ApoA-II were independently associated with an increased risk of mortality. Furthermore, receiver operating characteristic analysis identified XS-HDL-ApoA-II as the most potent prognostic marker for mortality. In conclusion, reduced small and XS-HDL subclasses, especially XS-HDL-ApoA-II, are strongly associated with increased all-cause mortality risk in CKD patients. Assessment of HDL subclass distribution could provide valuable clinical information and help identify patients at high risk.

Plasma activin A rises with declining kidney function and is independently associated with mortality in patients with chronic kidney disease

Background

Plasma (p-)activin A is elevated in chronic kidney disease-mineral and bone disorder (CKD-MBD). Activin A inhibition ameliorates CKD-MBD complications (vascular calcification and bone disease) in rodent CKD models. We examined whether p-activin A was associated with major adverse cardiovascular events (MACE), all-cause mortality and CKD-MBD complications in CKD patients.

Methods

The study included 916 participants (741 patients and 175 controls) from the prospective Copenhagen CKD cohort. Comparisons of p-activin A with estimated glomerular filtration rate (eGFR), coronary and thoracic aorta Agatston scores, and bone mineral density (BMD) were evaluated by univariable linear regression using Spearman's rank correlation, analysis of covariance and ordinal logistic regression with adjustments. Association of p-activin A with rates of MACE and all-cause mortality was evaluated by the Aalen-Johansen or Kaplan-Meier estimator, with subsequent multiple Cox regression analyses.

Results

P-activin A was increased by CKD stage 3 (124-225 pg/mL, P < .001) and correlated inversely with eGFR (r = -0.53, P < 0.01). P-activin A was associated with all-cause mortality [97 events, hazard ratio 1.55 (95% confidence interval 1.04; 2.32), P < 0.05] after adjusting for age, sex, diabetes mellitus (DM) and eGFR. Median follow-up was 4.36 (interquartile range 3.64-4.75) years. The association with MACE was not significant after eGFR adjustment. Agatston scores and BMD were not associated with p-activin A.

Conclusion

P-activin A increased with declining kidney function and was associated with all-cause mortality independently of age, sex, DM and eGFR. No association with MACE, vascular calcification or BMD was demonstrated.

Circulating Metabolites and Cardiovascular Disease in Asians with Chronic Kidney Disease

INTRODUCTION

Chronic kidney disease (CKD) is a growing public health problem, with significant burden of cardiovascular disease and mortality. The risk of cardiovascular disease in CKD is elevated beyond that predicted by traditional cardiovascular risk factors, suggesting that other factors may account for this increased risk. Through metabolic profiling, this study aimed to investigate the associations between serum metabolites and prevalent cardiovascular disease in Asian patients with CKD to provide insights into the complex interactions between metabolism, cardiovascular disease and CKD.

METHODS

This was a single-center cross-sectional study of 1,122 individuals from three ethnic cohorts in the population-based Singapore Epidemiology of Eye Disease (SEED) study (153 Chinese, 262 Indians, and 707 Malays) aged 40-80 years with CKD (estimated glomerular filtration rate <60 mL/min/1.73 m2). Nuclear magnetic resonance spectroscopy was used to quantify 228 metabolites from the participants' serum or plasma. Prevalent cardiovascular disease was defined as self-reported myocardial infarction, angina, or stroke. Multivariate logistic regression identified metabolites independently associated with cardiovascular disease in each ethnic cohort. Metabolites with the same direction of association with cardiovascular disease in all three cohorts were selected and subjected to meta-analysis.

RESULTS

Cardiovascular disease was present in 275 (24.5%). Participants with cardiovascular disease tend to be male; of older age; with hypertension, hyperlipidemia, and diabetes; with lower systolic and diastolic blood pressure (BP); lower high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol than those without cardiovascular disease. After adjusting for age, sex, systolic BP, diabetes, total cholesterol, and HDL cholesterol, 10 lipoprotein subclass ratios and 6 other metabolites were significantly associated with prevalent cardiovascular disease in at least one cohort. Meta-analysis with Bonferroni correction for multiple comparisons found that lower tyrosine, leucine, and valine concentrations and lower cholesteryl esters to total lipid ratio in intermediate-density lipoprotein (IDL) were associated with cardiovascular disease.

CONCLUSION

In Chinese, Indian, and Malay participants with CKD, prevalent cardiovascular disease was associated with tyrosine, leucine, valine, and cholesteryl esters to total lipid ratios in IDL. Increased cardiovascular risk in CKD patients may be contributed by altered amino acid and lipoprotein metabolism. The presence of CKD and ethnic differences may affect interactions between metabolites in health and disease, hence greater understanding will allow us to better risk stratify patients, and also individualize care with consideration of ethnic disparities.

Atherosclerosis Burdens in Diabetes Mellitus: Assessment by PET Imaging

Arteriosclerosis and its sequelae are the most common cause of death in diabetic patients and one of the reasons why diabetes has entered the top 10 causes of death worldwide, fatalities having doubled since 2000. The literature in the field claims almost unanimously that arteriosclerosis is more frequent or develops more rapidly in diabetic than non-diabetic subjects, and that the disease is caused by arterial inflammation, the control of which should therefore be the goal of therapeutic efforts. These views are mostly based on indirect methodologies, including studies of artery wall thickness or stiffness, or on conventional CT-based imaging used to demonstrate tissue changes occurring late in the disease process. In contrast, imaging with positron emission tomography and computed tomography (PET/CT) applying the tracers 18F-fluorodeoxyglucose (FDG) or 18F-sodium fluoride (NaF) mirrors arterial wall inflammation and microcalcification, respectively, early in the course of the disease, potentially enabling in vivo insight into molecular processes. The present review provides an overview of the literature from the more than 20 and 10 years, respectively, that these two tracers have been used for the study of atherosclerosis, with emphasis on what new information they have provided in relation to diabetes and which questions remain insufficiently elucidated.