The association of plasma lactate with incident cardiovascular outcomes: the ARIC Study

Relationship between lactate-to-albumin ratio and 28-day mortality in patients with exacerbation of chronic obstructive pulmonary disease admitted to the Intensive Care Unit

AIM

To explore the predictive value of lactate-to-albumin ratio (LAR) on 28-day mortality in patients with exacerbation of chronic obstructive pulmonary disease (AECOPD) admitted to the Intensive Care Unit (ICU).

METHODS

According to ICD-9 and ICD-10 diagnosis codes, patients diagnosed with AECOPD in the Medical Information Mart for Intensive Care IV (v.2.2) database were selected. The primary endpoint was 28-day mortality after ICU admission. We used receiver operating characteristic (ROC) curve, Kaplan-Meier (K-M) survival curve, logistic regression analyses and subgroup analysis to assess predictive power of LAR.

RESULTS

606 patients were included in this study. The 28-day mortality was 29.7%. The area under the ROC curves (AUC) for LAR were 0.641 [95% confidence interval (CI) 0.592-0.689], which was comparable with OASIS (AUC: 0.662; 95% CI 0.616-0.709; p = 0.471) and SOFA (AUC: 0.660; 95% CI 0.612-0.708; p = 0.500). The cutoff value of LAR was 0.645 by ROC curve. The high-LAR group showed a bad prognosis in K-M analysis (p < 0.001). Multivariate logistic regression shown that LAR was significantly associated with a poor outcome (odds ratio: 1.77; 95% CI 1.16-2.71; p = 0.008). Subgroup analysis showed no significant interaction of LAR with each subgroup (p for interaction: 0.175-0.775).

CONCLUSION

LAR is a rational and easily accessible marker, which is remarkably associated with 28-day mortality in ICU patients with AECOPD.

Prospective association between an obesogenic dietary pattern in early adolescence and metabolomics derived and traditional cardiometabolic risk scores in adolescents and young adults from the ALSPAC cohort

BACKGROUND

Dietary intake during early life may be a modifying factor for cardiometabolic risk (CMR). Metabolomic profiling may enable more precise identification of CMR in adolescence than traditional CMR scores. We aim to assess and compare the prospective associations between an obesogenic dietary pattern (DP) score at age 13 years with a novel vs. traditional CMR score in adolescence and young adulthood in the Avon Longitudinal Study of Parents and Children (ALSPAC).

METHODS

Study participants were ALSPAC children with diet diary data at age 13. The obesogenic DP z-score, characterized by high energy-density, high % of energy from total fat and free sugars, and low fibre density, was previously derived using reduced rank regression. CMR scores were calculated by combining novel metabolites or traditional risk factors (fat mass index, insulin resistance, mean arterial blood pressure, triacylglycerol, HDL and LDL cholesterol) at age 15 (n = 1808), 17 (n = 1629), and 24 years (n = 1760). Multivariable linear regression models estimated associations of DP z-score with log-transformed CMR z-scores.

RESULTS

Compared to the lowest tertile, the highest DP z-score tertile at age 13 was associated with an increase in the metabolomics CMR z-score at age 15 (β = 0.20, 95% CI 0.09, 0.32, p trend < 0.001) and at age 17 (β = 0.22, 95% CI 0.10, 0.34, p trend < 0.001), and with the traditional CMR z-score at age 15 (β = 0.15, 95% CI 0.05, 0.24, p trend 0.020). There was no evidence of an association at age 17 for the traditional CMR z-score (β = 0.07, 95% CI -0.03, 0.16, p trend 0.137) or for both scores at age 24.

CONCLUSIONS

An obesogenic DP was associated with greater CMR in adolescents. Stronger associations were observed with a novel metabolite CMR score compared to traditional risk factors. There may be benefits from modifying diet during adolescence for CMR health, which should be prioritized for further research in trials.

Recent Developments in Protein Lactylation in PTSD and CVD: Novel Strategies and Targets

In 1938, Corneille Heymans received the Nobel Prize in physiology for discovering that oxygen sensing in the aortic arch and carotid sinus was mediated by the nervous system. The genetics of this process remained unclear until 1991 when Gregg Semenza while studying erythropoietin, came upon hypoxia-inducible factor 1, for which he obtained the Nobel Prize in 2019. The same year, Yingming Zhao found protein lactylation, a posttranslational modification that can alter the function of hypoxia-inducible factor 1, the master regulator of cellular senescence, a pathology implicated in both post-traumatic stress disorder (PTSD) and cardiovascular disease (CVD). The genetic correlation between PTSD and CVD has been demonstrated by many studies, of which the most recent one utilizes large-scale genetics to estimate the risk factors for these conditions. This study focuses on the role of hypertension and dysfunctional interleukin 7 in PTSD and CVD, the former caused by stress-induced sympathetic arousal and elevated angiotensin II, while the latter links stress to premature endothelial cell senescence and early vascular aging. This review summarizes the recent developments and highlights several novel PTSD and CVD pharmacological targets. They include lactylation of histone and non-histone proteins, along with the related biomolecular actors such as hypoxia-inducible factor 1α, erythropoietin, acid-sensing ion channels, basigin, and Interleukin 7, as well as strategies to delay premature cellular senescence by telomere lengthening and resetting the epigenetic clock.

Circulating citric acid cycle metabolites and risk of cardiovascular disease in the PREDIMED study

BACKGROUND AND AIM

Plasma citric acid cycle (CAC) metabolites might be likely related to cardiovascular disease (CVD). However, studies assessing the longitudinal associations between circulating CAC-related metabolites and CVD risk are lacking. The aim of this study was to evaluate the association of baseline and 1-year levels of plasma CAC-related metabolites with CVD incidence (a composite of myocardial infarction, stroke or cardiovascular death), and their interaction with Mediterranean diet interventions.

METHODS AND RESULTS

Case-cohort study from the PREDIMED trial involving participants aged 55-80 years at high cardiovascular risk, allocated to MedDiets or control diet. A subcohort of 791 participants was selected at baseline, and a total of 231 cases were identified after a median follow-up of 4.8 years. Nine plasma CAC-related metabolites (pyruvate, lactate, citrate, aconitate, isocitrate, 2-hydroxyglutarate, fumarate, malate and succinate) were measured using liquid chromatography-tandem mass spectrometry. Weighted Cox multiple regression was used to calculate hazard ratios (HRs). Baseline fasting plasma levels of 3 metabolites were associated with higher CVD risk, with HRs (for each standard deviation, 1-SD) of 1.46 (95%CI:1.20-1.78) for 2-hydroxyglutarate, 1.33 (95%CI:1.12-1.58) for fumarate and 1.47 (95%CI:1.21-1.78) for malate (p of linear trend <0.001 for all). A higher risk of CVD was also found for a 1-SD increment of a combined score of these 3 metabolites (HR = 1.60; 95%CI: 1.32-1.94, p trend <0.001). This result was replicated using plasma measurements after one-year. No interactions were detected with the nutritional intervention.

CONCLUSION

Plasma 2-hydroxyglutarate, fumarate and malate levels were prospectively associated with increased cardiovascular risk.

CLINICAL TRIAL NUMBER

ISRCTN35739639.

Lactate acid level and prognosis of neonatal necrotizing enterocolitis: a retrospective cohort study based on pediatric-specific critical care database

OBJECTIVE

To investigate the relationship between lactate acid level and hospitalization mortality in neonatal necrotizing enterocolitis (NEC).

METHOD

Paediatric-specific critical care database collected clinical data from the intensive care unit of Children's Hospital Affiliated to Zhejiang University Medical College from 2010 to 2018. Clinical and laboratory examination information of NEC patients was collected and divided into the death group and discharge group to find out the risk factors affecting the prognosis through univariate and multivariate analysis.

RESULTS

Among 104 NEC neonates, the admission age was 7.5 days and the weight was 2.03 kg. Comparing the death group with the discharge group, there were significant differences in therapeutic regimen, pH, serum albumin, total protein, creatinine and lactate acid. Multivariate and threshold effect analysis showed that lactate acid had a linear correlation with hospital mortality, and newborns who died in the hospital had much higher lactate levels than those who were discharged. The mortality of NEC newborns increased by 40-45% for every 1 mmol/L increase in lactate acid level.

CONCLUSIONS

There was a correlation between lactate acid level and hospital mortality in newborns with NEC, and lactate acid level was an important index to evaluate the prognosis of NEC.

Advances in Glycolysis Metabolism of Atherosclerosis

Glycolysis is an important way for various cells such as vascular wall endothelial cells, smooth muscle cells, macrophages, and other cells to obtain energy. In pathological conditions, it can participate in the process of AS by regulating lipid deposition, calcification, angiogenesis in plaques, etc., together with its metabolite lactic acid. Recent studies have shown that lactate-related lactylation modifications are ubiquitous in the human proteome and are involved in the regulation of various inflammatory diseases. Combined with the distribution and metabolic characteristics of cells in the plaque in the process of AS, glycolysis-lactate-lactylation modification may be a new entry point for targeted intervention in atherosclerosis in the future. Therefore, this article intends to elaborate on the role and mechanism of glycolysis-lactate-lactylation modification in AS, as well as the opportunities and challenges in targeted therapy, hoping to bring some help to relevant scholars in this field. In atherosclerosis, glycolysis, lactate, and lactylation modification as a metabolic sequence affect the functions of macrophages, smooth muscle cells, endothelial cells, lymphocytes, and other cells and interfere with processes such as vascular calcification and intraplaque neovascularization to influence the progression of atherosclerosis.

Clarifying the link between the blood lactate concentration and cardiovascular risk

The blood lactate value at rest (Lac_rest) is linked to cardiovascular outcomes. It is unclear whether this association holds true in younger, healthy subjects, especially as the pathophysiological connection between Lac_rest and cardiometabolic disease is not well understood. The aim of this study is clarifying the link between Lac_rest and cardiovascular risk, and to study explanatory factors for the variance of Lac_rest concerning metabolism and physical activity in a population of healthy patient-athletes. The distribution and intra-individual variability of Lac_rest was assessed based on 9051 samples. The 10-year cardiovascular risk was then approximated using the Framingham risk score in a group of 1315 samples from patient-athletes. Cross-validated linear regression was used to analyze explanatory variables for Lac_rest and 10-year cardiovascular risk. Lac_rest is weakly associated with the Framingham score. This association disappears when adjusting for blood lipids. Lac_rest is also linked to the predominant type of exercise with endurance athletes featuring a higher Lac_rest. Lac_rest does not independently predict the estimated cardiovascular risk but is associated with lipid parameters. Moreover, the intra-individual variability of Lac_rest is high in a relevant number of subjects, which does not point towards the feasibility to use Lac_rest as an individual risk factor.

LACTATE CAN BE A MARKER OF METABOLIC SYNDROME IN SEVERE OBESITY?

Background:

In the last decades, numerous studies have confirmed the importance of lactate - by-product to the nutrient signal of the intracellular redox state - to regulatory functions in energy metabolism.

Aim:

To evaluate changes in blood lactate in patients with severe obesity and its correlation with body composition and metabolic profile.

Methods:

Twenty-four people with severe obesity (BMI=40 kg/m²) were evaluated in a prospective case-control study before and six months after Roux-in-Y gastric bypass. The blood lactate, total cholesterol, and fractions, C-reactive protein and HOMA-IR were analyzed after 12 h fasting. Body mass composition was evaluated by bioelectrical impedance and respiratory quotient was measured by indirect calorimetry.

Results:

The initial lactate level was 2.5±1.1 mmol/l and returned to normal level (1.9±3.6 mmol/l, p=0.0018) after surgery. This reduction was positively correlated with a decrease in BMI (p=0.0001), % free fat mass (p=0,001), % fat mass (p=0.001) and HOMA-IR (p=0.01). There was normalization of lactatemia in 70% of patients. There was no correlation between lactatemia and C-reactive protein.

Conclusions:

There was a significant improvement of metabolic parameters, normalization of blood lactate, fat mass loss, although these individuals remained with a high BMI.

Elevated levels of urine isocitrate, hydroxymethylglutarate, and formiminoglutamate are associated with arterial stiffness in Korean adults

Recent evidence suggests that cellular perturbations play an important role in the pathogenesis of cardiovascular diseases. Therefore, we analyzed the association between the levels of urinary metabolites and arterial stiffness. Our cross-sectional study included 330 Korean men and women. The brachial-ankle pulse wave velocity was measured as a marker of arterial stiffness. Urinary metabolites were evaluated using a high-performance liquid chromatograph-mass spectrometer. The brachial-ankle pulse wave velocity was found to be positively correlated with l-lactate, citrate, isocitrate, succinate, malate, hydroxymethylglutarate, α-ketoisovalerate, α-keto-β-methylvalerate, methylmalonate, and formiminoglutamate among men. Whereas, among women, the brachial-ankle pulse wave velocity was positively correlated with cis-aconitate, isocitrate, hydroxymethylglutarate, and formiminoglutamate. In the multivariable regression models adjusted for conventional cardiovascular risk factors, three metabolite concentrations (urine isocitrate, hydroxymethylglutarate, and formiminoglutamate) were independently and positively associated with brachial-ankle pulse wave velocity. Increased urine isocitrate, hydroxymethylglutarate, and formiminoglutamate concentrations were associated with brachial-ankle pulse wave velocity and independent of conventional cardiovascular risk factors. Our findings suggest that metabolic disturbances in cells may be related to arterial stiffness.

Glycolysis Metabolites and Risk of Atrial Fibrillation and Heart Failure in the PREDIMED Trial

The increased prevalence of atrial fibrillation (AF) and heart failure (HF) highlights the need to better understand the mechanisms underlying these cardiovascular diseases (CVDs). In the present study, we aimed to evaluate the association between glycolysis-related metabolites and the risk of AF and HF in a Mediterranean population at high risk of CVD. We used two case-control studies nested within the PREDIMED trial. A total of 512 incident AF cases matched to 734 controls, and 334 incident HF cases matched to 508 controls, were included. Plasma metabolites were quantified by using hydrophilic interaction liquid chromatography coupled with high-resolution negative ion mode MS detection. Conditional logistic regression analyses were performed. The results showed no association between baseline plasma glycolysis intermediates and other related metabolites with AF. Only phosphoglycerate was associated with a higher risk of HF (OR _{for 1 SD increase}: 1.28; 95% CI: 1.06, 1.53). The present findings do not support a role of the glycolysis pathway in the pathogenesis of AF. However, the increased risk of HF associated with phosphoglycerate requires further studies.

Insulin resistance and depressed cardiac G6PD activity induced by glucocorticoid exposure during pregnancy are attenuated by maternal estrogen-progestin therapy

This study aimed to investigate the effects of maternal combined oral contraceptive (COC) on dams that were exposed to late gestational glucocorticoids (GC). Twenty-four pregnant female rats were randomly allotted into 4 groups of 6 dams each. Dams received COC (combination of 1.0 μg ethinylestradiol and 5.0 μg levonorgestrel p.o.) between 3rd and 11^th week after delivery with or without prior exposure to GC (dexamethasone; 0.2 mg/kg p.o.) that was administered between gestational days 14-19. Data showed that late-gestational GC exposure led to insulin resistance (IR), increased cardiac adenosine deaminase (ADA), xanthine oxidase (XO), lactate, lactate dehydrogenase (LDH), and disrupted cardiac glucose-6-phosphate dehydrogenase (G6PD)-dependent antioxidant defenses. On the other hand, maternal COC treatment in dams not exposed to gestational GC led to IR, increased cardiac XO, LDH and defective cardiac G6PD-dependent antioxidant defenses. However, maternal COC with prior gestational GC exposure led to attenuated IR, cardiac ADA, UA, LDH, and improved cardiac G6PD-dependent antioxidant defenses but worsened cardiac triglyceride (TG) accumulation when compared with dam with gestational GC exposure without maternal COC. Taken together, the findings of this study provide evidence that maternal COC treatment improves late gestational GC-programmed effects. This is however accompanied with enhanced cardiac TG accumulation.

Dexamethasone causes defective glucose-6-phosphate dehydrogenase dependent antioxidant barrier through endoglin in pregnant and nonpregnant rats

Glucocorticoid therapy has been associated with adverse cardiometabolic effects during pregnancy. Inflammation-mediated cardiac dysfunction, an independent risk factor for morbidity and mortality, has been linked to defective glucose-6-phosphate dehydrogenase (G6PD) dependent antioxidant defenses and increased endoglin expression. We therefore sought to investigate the effects of dexamethasone (DEX) on cardiac endoglin and G6PD-dependent antioxidant defense. Twenty-four rats were randomly assigned to nonpregnant (PRE(-)), DEX-exposed nonpregnant (PRE(-) + DEX), pregnant (PRE(+)), and DEX-exposed pregnant (PRE(+) + DEX) rats, respectively (n = 6 per group). PRE(-) and PRE(+) rats received vehicle (per oral (po)), while PRE(-) + DEX and PRE(+) + DEX groups were administered DEX (0.2 mg/kg po) between gestational days 14 and 19, respectively. Results showed that DEX caused increased cardiac pro-inflammatory markers (adenosine deaminase (ADA) activity, endoglin, vascular cell adhesion molecule-1 (VCAM-1), tissue injury markers (LDH, GGT, AST, ALT, and ALP), metabolic disturbances (elevated fasting plasma glucose, free fatty acid (FFA), lactate, cardiac FFA, and lactate) and depressed G6PD-dependent antioxidant defenses (G6PD activity, reduced glutathione/oxidized glutathione ratio, and nitric oxide) in pregnant and nonpregnant rats. The present study demonstrates that DEX led to increased cardiac endoglin and VCAM-1 that is accompanied by defective G6PD-dependent antioxidant defenses but not cardiac lipid accumulation in both pregnant and nonpregnant rats.

Effect of Schisandra Chinensis Extract Supplementation on Quadriceps Muscle Strength and Fatigue in Adult Women: A Randomized, Double-Blind, Placebo-Controlled Trial

The fruit of Schisandra chinensis (SC) is a well-known traditional herb used for pharmacological purposes in Asian countries (e.g., Korea, China, and Japan). In animal studies, SC extract supplementation had beneficial effects on muscle strength and lactate level. However, the effect of SC extract supplementation on skeletal muscle strength and lactate at rest in humans remains unclear. The purpose of this study was to evaluate the effect of SC extract supplementation on quadriceps muscle strength (QMS) and lactate at rest in adult women. Forty five healthy post-menopausal middle-aged women (61.9 ± 8.4 years) were randomly divided into the SC (n = 24) or the placebo group (n = 21). The SC group consumed 1000 mg of SC extract per day, whereas the placebo group consumed 1000 mg of starch per day for 12 weeks. The difference in muscle mass, physical function, and biomarkers and the relative changes between baseline and 12 weeks were evaluated. We used two-factor repeated measures analysis of variance (ANOVA) to determine interaction (group × time) effects for variables. Statistical significance was accepted at p < 0.05. In ANOVA results, QMS (p = 0.001) and lactate level (p = 0.038) showed significant interactions. With paired t-tests, QMS was significantly increased (p < 0.001) and lactate level at rest was significantly decreased (p < 0.05) after 12 weeks in the SC group. However, no interactions were found between the other variables. Supplementation of SC extract may help to improve QMS as well as decrease lactate level at rest in adult women. We believe that SC extract is a health supplement that can support healthy life in this population.

The utility of point of care serum lactate in predicting serious adverse outcomes among critically ill adult patients at urban emergency departments of tertiary hospitals in Tanzania

Background

Elevated serum lactate levels have been shown in numerous studies to be associated with serious adverse events, including mortality. Point of care lactate level is increasingly available in resource-limited emergency department (ED) settings. However, little is known about the predictive ability of for serious adverse events.

Aim of the study

We aimed to describe the utility of serum lactate level as a predictor of 24-h serious adverse events among adult patients presenting at the Emergency Medicine Department (EMD) of Muhimbili National Hospital (MNH) and MUHAS Academic Medical Center (MAMC).

Methods

This was a prospective observational study involving adult patients presenting to the EMD-MNH and MAMC from 1 September 2018 and 31 October 2018. Eligible patients with at least one lactate level test drawn while in the ED were examined in terms of their demographics, relevant clinical characteristics, and any serious adverse event (SAE) within 24 h of arrival. The sensitivity and specificity of lactate level to predict outcomes of interest were determined using the best cut-off point constructed from AUROC to see how well lactate level could discriminate which patients would have adverse events in the next 24 h. Categorical and continuous variables were compared with the chi-square test and two-sample t test, respectively.

Results

We screened 2057 (20.9%) out of 9828 patients who presented during study period, and enrolled 387 (18.8%). The overall median age was 54 years (interquartile range 40–68 years) and 206 (53.2%) were male. Using local triaging system, a total of 322 (83.2%) was triaged as an emergency category. The mean lactate level was 3.2 ± 3.6 mmol/L, 65 (16.8%) patients developed at least one SAE, with 42 (11%) who required ICU/HDU, 37 (10%) needed ventilator support, 10 (3%) required inotropes, and 9 (2%) developed cardiac arrest. The overall 24-h mortality was 28 (7%). The AUC of serum lactate level for overall 24-h mortality was 0.801 (95%CI, 0.7–0.9, P ≤ 0.001). At the optimal cutoff value (3.8 mmol/L), lactate level had a sensitivity and specificity for 24-h mortality of 64% and 85%, respectively. Mortality of the high-lactate level group (³3.8 mmol/L) was significantly higher than that of the low-lactate level group (< 3.8 mmol/L), 23.8% vs. 2.9%, respectively (95%CI 3.8–17.2, p < 0.001), with the relative risk of mortality in the high-lactate level group being 8.1 times higher compared to the low-lactate level group.

Conclusion

The utility of lactate level in predicting mortality was similar to that seen in high-resource settings. A serum lactate level of ³3.8 mmol/L predicted 24-h serious adverse events in unselected patients seen in the high-acuity area of our ED. Incorporating serum lactate level in ED in lower- and middle-income countries (LMICs) can help identify patients at risk of developing serious adverse events.

High released lactate by epicardial fat from coronary artery disease patients is reduced by dapagliflozin treatment

BACKGROUND AND AIMS

Dapagliflozin, a sodium-glucose co-transporter 2 inhibitor, improves glucose uptake by epicardial adipose tissue (EAT). However, its metabolism might raise the lactate production and acidosis under hypoxia conditions, i.e. coronary artery disease (CAD), or lipogenesis and, in consequence, expand adipose tissue. Since lactate secreted by adipose tissue is correlated with tissue stress and inflammation, our aim was to study glucose metabolism by epicardial fat in CAD and its regulation by dapagliflozin.

METHODS

Paired EAT and subcutaneous adipose tissue (SAT) biopsies from 49 patients who underwent open-heart surgery were cultured and split into three equal pieces, some treated with and others without dapagliflozin at 10 or 100 μM for 6 h. Anaerobic glucose metabolites were measured in supernatants of fat pads, and acidosis on adipogenesis-induced primary culture cells was analysed by colorimetric or fluorescence assays. Gene expression levels were assessed by real-time polymerase chain reaction.

RESULTS

Our results showed that dapagliflozin reduced the released lactate and acidosis in epicardial fat (p < 0.05) without changes in lipid storage-involved genes. In addition, this drug induced gene expression levels of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α), a mitochondrial biogenesis-involved gene in both EAT and SAT (p < 0.05). After splitting the population regarding the presence of CAD, we observed higher lactate production in EAT from these patients (2.46 [1.75-3.47] mM), which was reduced after treatment with dapagliflozin 100 μM (1.99 [1.08-2.99] mM, p < 0.01).

CONCLUSIONS

Dapagliflozin improved glucose metabolism without lipogenesis-involved gene regulation or lactate production, mainly in patients with CAD. These results suggest an improvement of glucose oxidation metabolism that can contribute to cardiovascular benefits.

Targeted Metabolomic Profiling of Plasma and Survival in Heart Failure Patients

OBJECTIVES

This study sought to derive and validate plasma metabolite associations with survival in heart failure (HF) patients.

BACKGROUND

Profiling of plasma metabolites to predict the course of HF appears promising, but validation and incremental value of these profiles are less established.

METHODS

Patients (n = 1,032) who met Framingham HF criteria with a history of reduced ejection fraction were randomly divided into derivation and validation cohorts (n = 516 each). Amino acids, organic acids, and acylcarnitines were quantified using mass spectrometry in fasting plasma samples. We derived a prognostic metabolite profile (PMP) in the derivation cohort using Lasso-penalized Cox regression. Validity was assessed by 10-fold cross validation in the derivation cohort and by standard testing in the validation cohort. The PMP was analyzed as both a continuous variable (PMPscore) and dichotomized at the median (PMPcat), in univariate and multivariate models adjusted for clinical risk score and N-terminal pro-B-type natriuretic peptide.

RESULTS

Overall, 48% of patients were African American, 35% were women, and the average age was 69 years. After a median follow-up of 34 months, there were 256 deaths (127 and 129 in derivation and validation cohorts, respectively). Optimized modeling defined the 13 metabolite PMPs, which was cross validated as both the PMPscore (hazard ratio [HR]: 3.27; p < 2 × 10^-16) and PMPcat (HR: 3.04; p = 2.93 × 10^-8). The validation cohort showed similar results (PMPscore HR: 3.9; p < 2 × 10^-16 and PMPcat HR: 3.99; p = 3.47 × 10^-9). In adjusted models, PMP remained associated with mortality in the cross-validated derivation cohort (PMPscore HR: 1.63; p = 0.0029; PMPcat HR: 1.47; p = 0.081) and the validation cohort (PMPscore HR: 1.54; p = 0.037; PMPcat HR: 1.69; p = 0.043).

CONCLUSIONS

Plasma metabolite profiles varied across HF subgroups and were associated with survival incremental to conventional predictors. Additional investigation is warranted to define mechanisms and clinical applications.

Inhibition of adenosine deaminase and xanthine oxidase by valproic acid abates hepatic triglyceride accumulation independent of corticosteroids in female rats treated with estrogen-progestin

Elevated circulating uric acid has been postulated to play an important pathophysiological role in estrogen-progestin combined oral contraceptive (COC)-induced hypertension and endothelial dysfunction. We hypothesized that disruption of glucoregulation and liver triglyceride (TG) accumulation induced by COC use would be abated by valproic acid (VPA) treatment through suppression of adenosine deaminase (ADA) and xanthine oxidase (XO) activities. Female Wistar rats aged 9-10 weeks were treated with a combination of estrogen-progestin COC steroids (1.0 μg ethinylestradiol and 5.0 μg levonorgestrel; p.o.) with or without VPA (100.0 mg/kg; p.o.) daily for 6 weeks. The result shows that the disrupted glucoregulation and associated elevated hepatic ADA activity, plasma and hepatic XO activity, uric acid (UA), TG/HDL-cholesterol, total cholesterol, and malondialdehyde induced by COC treatment were attenuated by VPA treatment. However, VPA did not have any effect on plasma aldosterone, corticosterone, ADA, circulating and hepatic free fatty acid. Our results demonstrate that suppression of plasma and hepatic XO activities, along with hepatic ADA activity and UA by VPA treatment, protects against disrupted glucoregulation and increased liver TG by COC independent of elevated corticosteroids. The findings imply that VPA would provide protection against the development of cardiometabolic disorder via inhibition of the ADA/XO/UA-mediated pathway.

Circulating metabolomic profile can predict dyslipidemia in HIV patients undergoing antiretroviral therapy

BACKGROUND AND AIMS

Dyslipidemia in HIV-infected patients is unique and pathophysiologically associated with host factors, HIV itself and the use of antiretroviral therapy (ART). The use of nuclear magnetic resonance spectroscopy (NMR) provides additional data to conventional lipid measurements concerning the number of lipoprotein subclasses and particle sizes.

METHODS

To investigate the ability of lipoprotein profile, we used a circulating metabolomic approach in a cohort of 103 ART-naive HIV-infected patients, who were initiating non-nucleoside analogue transcriptase inhibitor (NNRTI)-based ART, and we subsequently followed up these patients for 36 months. Univariate and multivariate analyses were performed to evaluate the predictive power of NMR spectroscopy.

RESULTS

VLDL-metabolism (including VLDL lipid concentrations, sizes, and particle numbers), total triglycerides and lactate levels resulted in good classifiers of dyslipidemia (AUC 0.903). Total particles/HDL-P ratio was significantly higher in ART-associated dyslipidemia compared to ART-normolipidemia (p = 0.001). Large VLDL-Ps were positively associated with both LDL-triglycerides (ρ 0.682, p < 0.001) and lactate concentrations (ρ 0.416, p < 0.001), the last one a marker of mitochondrial low oxidative capacity.

CONCLUSIONS

Our data suggest that circulating metabolites have better predictive values for HIV/ART-related dyslipidemia onset than do the biochemical markers associated with conventional lipid measurements. NMR identifies changes in VLDL-P, lactate and LDL-TG as potential clinical markers of baseline HIV-dyslipidemia predisposition. Differences in circulating metabolomics, especially differences in particle size, are indicators of important derangements of mitochondrial function that are linked to ART-related dyslipidemia.

Molecular Epidemiology of Heart Failure: Translational Challenges and Opportunities

Heart failure (HF) is the end-stage of all heart disease and arguably constitutes the greatest unmet therapeutic need in cardiovascular medicine today. Classic epidemiological studies have established clinical risk factors for HF, but the cause remains poorly understood in many cases. Biochemical analyses of small case-control series and animal models have described a plethora of molecular characteristics of HF, but a single unifying pathogenic theory is lacking. Heart failure appears to result not only from cardiac overload or injury but also from a complex interplay among genetic, neurohormonal, metabolic, inflammatory, and other biochemical factors acting on the heart. Recent development of robust, high-throughput tools in molecular biology provides opportunity for deep molecular characterization of population-representative cohorts and HF cases (molecular epidemiology), including genome sequencing, profiling of myocardial gene expression and chromatin modifications, plasma composition of proteins and metabolites, and microbiomes. The integration of such detailed information holds promise for improving understanding of HF pathophysiology in humans, identification of therapeutic targets, and definition of disease subgroups beyond the current classification based on ejection fraction which may benefit from improved individual tailoring of therapy. Challenges include: 1) the need for large cohorts with deep, uniform phenotyping; 2) access to the relevant tissues, ideally with repeated sampling to capture dynamic processes; and 3) analytical issues related to integration and analysis of complex datasets. International research consortia have formed to address these challenges and combine datasets, and cohorts with up to 1 million participants are being collected. This paper describes the molecular epidemiology of HF and provides an overview of methods and tissue types and examples of published and ongoing efforts to systematically evaluate molecular determinants of HF in human populations.

Kidney Disease Measures and Left Ventricular Structure and Function: The Atherosclerosis Risk in Communities Study

Background

Heart failure is one of the most important complications of chronic kidney disease (CKD). However, few studies comprehensively investigated left ventricular (LV) structure and function in relation to 2 key CKD measures, estimated glomerular filtration rate (eGFR) and urine albumin/creatinine ratio (ACR).

Methods and Results

Among 4175 ARIC (Atherosclerosis Risk in Communities) participants (aged 66–90 years during 2011–2013), we quantified the association of eGFR and ACR with echocardiogram parameters of LV mass, size, systolic function, and diastolic function. Adjusting for demographic variables, both CKD measures were significantly associated with most echocardiogram parameters. Additionally accounting for other potential confounders, we observed significantly higher LV mass index according to reduced eGFR (82.3 [95% confidence interval (CI), 77.6–87.0] g/m² for eGFR <30 mL/min per 1.73 m², 80.9 [95% CI, 77.3–84.6] g/m² for eGFR 30–44 mL/min per 1.73 m², and 80.1 [95% CI, 76.7–83.5] g/m² for eGFR 45–59 mL/min per 1.73 m² compared with 78.7 [95% CI, 75.3–82.1] g/m² for eGFR 75–89 mL/min per 1.73 m²; trend P<0.001). Regarding LV size and function, significant differences were observed for some parameters, particularly at eGFR <30 mL/min per 1.73 m². For ACR, the associations remained significant for most parameters (eg, LV mass index, 91.5 [95% CI, 86.6–96.5] g/m² for ACR ≥300 mg/g and 82.9 [95% CI, 79.4–86.3] g/m² for ACR 30–299 mg/g compared with 77.7 [95% CI, 74.4–81.1] g/m² for ACR <10 mg/g [trend P<0.001]; left arterial volume index, 24.9 [95% CI, 22.9–26.8] and 24.7 [95% CI, 23.4–26.1] mL/m² compared with 23.4 [95% CI, 22.1–24.7] mL/m², respectively [trend P=0.010]). Dichotomizing echo parameters with clinical thresholds, the stronger relationships of ACR over eGFR were further evident.

Conclusions

LV mass was related to both CKD measures, whereas LV size and function were robustly associated with albuminuria. These results have implications for pathophysiological processes behind cardiorenal syndrome and targeted cardiac assessment in patients with CKD.

Exercise timing and blood lactate concentrations in individuals with type 2 diabetes

The purpose of this study was to characterize how resistance exercise prior to or after a meal alters fasting and postprandial blood lactate concentrations in individuals with type 2 diabetes. Obese individuals with type 2 diabetes (N = 12) completed three 2-day trials, including (i) no exercise (NoEx), (ii) resistance exercise prior to dinner (Ex-M), and (iii) resistance exercise beginning at 45 min postdinner (M-Ex). During day 1 of each trial, fasting and postprandial blood lactate concentrations, perceived exertion, and substrate oxidation were measured, and subsequently on day 2 the following morning fasting blood lactate was measured. The premeal lactate incremental area under the curve (iAUC) during Ex-M (109 ± 66 mmol·L−1·1.6 h−1) was over 100-fold greater (P < 0.01) compared with NoEx (−15 ± 24 mmol·L−1·1.6 h−1) and M-Ex (−2 ± 18 mmol·L−1·1.6 h−1). The postprandial lactate iAUC during M-Ex (304 ± 116 mmol·L−1·4 h−1) was over 2-fold greater (P < 0.01) compared with NoEx (149 ± 74 mmol·L−1·4 h−1) and Ex-M (−140 ± 196 mmol·L−1·4 h−1). Average lactate during exercise was ∼45% greater (P = 0.03) during M-Ex (3.2 ± 0.9 mmol/L) compared with Ex-M (2.2 ± 0.9 mmol/L), but the change in lactate during Ex-M (2.4 ± 1.6 mmol/L) or M-Ex (2.3 ± 1.3 mmol/L) was not different (P > 0.05). Perceived exertion, substrate oxidation, or fasting blood lactate concentrations the day after testing were not different between trials. Blood lactate concentrations during acute resistance exercise are greater when exercise is performed in the postprandial period. Acute resistance exercise performed the night prior does not alter fasting blood lactate concentrations the following morning.

Effect of chronic consumption of blackberry extract on high-fat induced obesity in rats and its correlation with metabolic and brain outcomes

Flavonoids have been presented as potential protectors against metabolic and cognitive dysfunction. However, mechanisms underlying these 'claims' have not been sufficiently explored. To analyse the effect of long-term supplementation with blackberry extract (BE) in the context of a high-fat or a standard diet, Wistar rats were divided into 4 groups (n = 6) fed with a standard or a high-fat diet, with or without BE supplementation at 25 mg per kg body weight per day. A high-fat diet significantly impaired glucose tolerance and increased body weight, caloric ingestion, very-low-density lipoprotein, triglycerides and cholesterol. Furthermore, it was observed that a high-fat diet increased dopamine content in the prefrontal cortex and decreased brain derived neurotrophic factor (BDNF) levels both in the prefrontal cortex and in plasma. BE supplementation only affected some of these aspects. BE slightly improved glucose metabolism and significantly decreased levels of lactate, independent of diet. BE decreased levels of BDNF and also interacted with the dopaminergic system, increasing dopamine turnover in the striatum, and reverting dopamine content induced by a high-fat diet in the prefrontal cortex. This study shows that, despite some particular benefits of anthocyanin supplementation, some long-term effects may not be desirable and further studies are needed to optimize ingestion conditions.

Mitochondrial dysfunction and oxidative stress in patients with chronic kidney disease

Mitochondria abnormalities in skeletal muscle may contribute to frailty and sarcopenia, commonly present in patients with chronic kidney disease (CKD). Dysfunctional mitochondria are also a major source of oxidative stress and may contribute to cardiovascular disease in CKD. We tested the hypothesis that mitochondrial structure and function worsens with the severity of CKD. Mitochondrial volume density, mitochondrial DNA (mtDNA) copy number, BNIP3, and PGC1α protein expression were evaluated in skeletal muscle biopsies obtained from 27 subjects (17 controls and 10 with CKD stage 5 on hemodialysis). We also measured mtDNA copy number in peripheral blood mononuclear cells (PBMCs), plasma isofurans, and plasma F2‐isoprostanes in 208 subjects divided into three groups: non‐CKD (eGFR>60 mL/min), CKD stage 3–4 (eGFR 60–15 mL/min), and CKD stage 5 (on hemodialysis). Muscle biopsies from patients with CKD stage 5 revealed lower mitochondrial volume density, lower mtDNA copy number, and higher BNIP3 content than controls. mtDNA copy number in PBMCs was decreased with increasing severity of CKD: non‐CKD (6.48, 95% CI 4.49–8.46), CKD stage 3–4 (3.30, 95% CI 0.85–5.75, P = 0.048 vs. non‐CKD), and CKD stage 5 (1.93, 95% CI 0.27–3.59, P = 0.001 vs. non‐CKD). Isofurans were higher in patients with CKD stage 5 (median 59.21 pg/mL, IQR 41.76–95.36) compared to patients with non‐CKD (median 49.95 pg/mL, IQR 27.88–83.46, P = 0.001), whereas F2‐isoprostanes did not differ among groups. Severity of CKD is associated with mitochondrial dysfunction and markers of oxidative stress. Mitochondrial abnormalities, which are common in skeletal muscle from patients with CKD stage 5, may explain the muscle dysfunction associated with frailty and sarcopenia in CKD. Further studies are required to evaluate mitochondrial function in vivo in patients with different CKD stages.

Increased plasma lactate level is associated with subclinical cardiovascular damage in patient with non-dipping hypertension

OBJECTIVE

To evaluate the difference of plasma lactate level between dipping and non-dipping hypertension, and to investigate the effects of lactate on subclinical cardiovascular damages in dipping and non-dipping hypertension.

METHODS

According to 24 h ambulatory blood pressure monitoring, 236 patients with dipping and 152 with non-dipping hypertension were included. Clinical characteristics were collected and compared between dipping and non-dipping groups. Left ventricle hypertrophy (LVH) and N-terminal pro-B type natriuretic peptide (NT-proBNP) level were used to evaluate subclinical cardiovascular damage. Multivariate regression analysis was performed to evaluate the relationship between lactate and LVH and NT-proBNP elevation.

RESULTS

Compared to dipping hypertension, plasma levels of lactate and NT-proBNP in non-dipping hypertension group were significantly higher. Moreover, the value of left ventricle mass index to height (LVMI/height) was also significantly higher in non-dipping group, and the percentage of patient with LVH was also higher in non-dipping group (36.8% vs. 28.9%, P < 0.05). Multivariate regression analysis revealed that in non-dipping group, after fully adjustment, the associations between lactate with LVH and NT-proBNP remained significant, with odds ratio (OR) of 1.18 (95% confidence interval [CI] of 1.13-1.24) in LVH and OR of 1.16 in NT-proBNP (95% CI of 1.10-1.23), respectively. Nonetheless, the associations between lactate with LVH and NT-proBNP elevation in dipping group were diminished to statistical nonsignificance.

CONCLUSION

Plasma lactate level in non-dipping hypertension is significantly higher than dipping hypertension, and this difference may be the potential mechanism non-dipping hypertension contributes to greater targeted organ damage.

GCKR and PPP1R3B identified as genome-wide significant loci for plasma lactate: the Atherosclerosis Risk in Communities (ARIC) study

AIM

To investigate the genetic influence of circulating lactate level, a marker of oxidative capacity associated with diabetes.

METHODS

We conducted a genome-wide association study of log-transformed plasma lactate levels in 6901 European-American participants in the Atherosclerosis Risk in Communities study. For regions that achieved genome-wide significance in European-American participants, we conducted candidate region analysis in African-American subjects and tested for interaction between metformin use and the index single nucleotide polymorphisms for plasma lactate in European-American subjects.

RESULTS

The genome-wide association study in European-American subjects identified two genome-wide significant loci, GCKR (rs1260326, T allele β=0.08; P=1.8×10(-47) ) and PPP1R3B/LOC157273 (rs9987289, A allele β=0.06; P=1.6×10(-9) ). The index single nucleotide polymorphisms in these two loci explain 3.3% of the variance in log-transformed plasma lactate levels among the European-American subjects. In the African-American subjects, based on a region-significant threshold, the index single nucleotide polymorphism at GCKR was associated with plasma lactate but that at PPP1R3B/LOC157273 was not. Metformin use appeared to strengthen the association between the index single nucleotide polymorphism at PPP1R3B/LOC157273 and plasma lactate in European-American subjects (P for interaction=0.01).

CONCLUSIONS

We identified GCKR and PPP1R3B/LOC157273 as two genome-wide significant loci of plasma lactate. Both loci are associated with other diabetes-related phenotypes. These findings increase our understanding of the genetic control of lactate metabolism.

Characterization of Lactate Sensors Based on Lactate Oxidase and Palladium Benzoporphyrin Immobilized in Hydrogels

An optical biosensor for lactate detection is described. By encapsulating enzyme-phosphor sensing molecules within permeable hydrogel materials, lactate-sensitive emission lifetimes were achieved. The relative amount of monomer was varied to compare three homo- and co-polymer materials: poly(2-hydroxyethyl methacrylate) (pHEMA) and two copolymers of pHEMA and poly(acrylamide) (pAam). Diffusion analysis demonstrated the ability to control lactate transport by varying the hydrogel composition, while having a minimal effect on oxygen diffusion. Sensors displayed the desired dose-variable response to lactate challenges, highlighting the tunable, diffusion-controlled nature of the sensing platform. Short-term repeated exposure tests revealed enhanced stability for sensors comprising hydrogels with acrylamide additives; after an initial "break-in" period, signal retention was 100% for 15 repeated cycles. Finally, because this study describes the modification of a previously developed glucose sensor for lactate analysis, it demonstrates the potential for mix-and-match enzyme-phosphor-hydrogel sensing for use in future multi-analyte sensors.

Endurance training alters basal erythrocyte MCT-1 contents and affects the lactate distribution between plasma and red blood cells in T2DM men following maximal exercise

Chronic elevated lactate levels are associated with insulin resistance in patients with type 2 diabetes mellitus (T2DM). Furthermore, lactacidosis plays a role in limiting physical performance. Erythrocytes, which take up lactate via monocarboxylate transporter (MCT) proteins, may help transport lactate within the blood from lactate-producing to lactate-consuming organs. This study investigates whether cycling endurance training (3 times/week for 3 months) alters the basal erythrocyte content of MCT-1, and whether it affects lactate distribution kinetics in the blood of T2DM men (n = 10, years = 61 ± 9, body mass index = 31 ± 3 kg/m(2)) following maximal exercise (WHO step-incremental cycle ergometer test). Immunohistochemical staining indicated that basal erythrocyte contents of MCT-1 protein were up-regulated (+90%, P = 0.011) post-training. Erythrocyte and plasma lactate increased from before acute exercise (= resting values) to physical exhaustion pre- as well as post-training (pre-training: +309%, P = 0.004; +360%, P < 0.001; post-training: +318%, P = 0.008; +300%, P < 0.001), and did not significantly decrease during 5 min recovery. The lactate ratio (erythrocytes:plasma) remained unchanged after acute exercise pre-training, but was significantly increased after 5 min recovery post-training (compared with the resting value) (+22%, P = 0.022). The results suggest an increased time-delayed influx of lactate into erythrocytes following an acute bout of exercise in endurance-trained diabetic men.

Circulating peroxiredoxin 4 and type 2 diabetes risk: the Prevention of Renal and Vascular Endstage Disease (PREVEND) study

AIMS/HYPOTHESIS

Oxidative stress plays a key role in the development of type 2 diabetes mellitus. We previously showed that the circulating antioxidant peroxiredoxin 4 (Prx4) is associated with cardiometabolic risk factors. We aimed to evaluate the association of Prx4 with type 2 diabetes risk in the general population.

METHODS

We analysed data on 7,972 individuals from the Prevention of Renal and Vascular End-stage Disease (PREVEND) study (49% men, aged 28-75 years) with no diabetes at baseline. Logistic regression models adjusted for age, sex, smoking, waist circumference, hypertension and family history of diabetes were used to estimate the ORs for type 2 diabetes.

RESULTS

During a median follow up of 7.7 years, 496 individuals (288 men; 58%) developed type 2 diabetes. The median (Q1-Q3) Prx4 level was 0.84 (0.53-1.40) U/l in individuals who developed type 2 diabetes and 0.68 (0.43-1.08) U/l in individuals who did not develop type 2 diabetes. For every doubling of Prx4 levels, the adjusted OR (95% CI) for type 2 diabetes was 1.16 (1.05-1.29) in the whole population; by sex, it was 1.31 (1.14-1.50) for men and 1.03 (0.87-1.21) for women. Further adjustment for other clinical measures did not materially change the results. The addition of Prx4 to a validated diabetes risk score significantly improved the prediction of type 2 diabetes in men (p = 0.002 for reclassification improvement).

CONCLUSIONS/INTERPRETATION

Our findings suggest that elevated serum Prx4 levels are associated with a higher risk of incident type 2 diabetes. For men, taking Prx4 into consideration can improve type 2 diabetes prediction over a validated diabetes risk score; in contrast, there is no improvement in risk prediction for women.