Dynamic magnetic resonance measurements of calf muscle oxygenation and energy metabolism in peripheral artery disease

Background

Clinical assessments of peripheral artery disease (PAD) severity are insensitive to pathophysiological changes in muscle tissue oxygenation and energy metabolism distal to the affected artery.

Purpose

To quantify the blood oxygenation level‐dependent (BOLD) response and phosphocreatine (PCr) recovery kinetics on a clinical MR system during a single exercise‐recovery session in PAD patients.

Study Type

Case–control study.

Subjects

Fifteen Fontaine stage II patients, and 18 healthy control subjects

Field Strength/Sequence

Interleaved dynamic multiecho gradient‐echo ¹H T₂* mapping and adiabatic pulse‐acquire ³¹P‐MR spectroscopy at 3T.

Assessment

Blood pressure in the arms and ankles were measured to determine the ankle‐brachial index (ABI). Subjects performed a plantar flexion exercise‐recovery protocol. The gastrocnemius and soleus muscle BOLD responses were characterized using the T₂* maps. High‐energy phosphate metabolite concentrations were quantified by fitting the series of ³¹P‐MR spectra. The PCr recovery time constant (τ_PCr) was derived as a measure of in vivo mitochondrial oxidative capacity.

Statistical Tests

Comparisons between groups were performed using two‐sided Mann–Whitney U‐tests. Relations between variables were assessed by Pearson's r correlation coefficients.

Results

The amplitude of the functional hyperemic BOLD response in the gastrocnemius muscle was higher in PAD patients compared with healthy subjects (–3.8 ± 1.4% vs. –1.4 ± 0.3%; P < 0.001), and correlated with the ABI (r = 0.79; P < 0.001). PCr recovery was slower in PAD patients (τ_PCr = 52.0 ± 13.5 vs. 30.3 ± 9.7 sec; P < 0.0001), and correlated with the ABI (r = –0.64; P < 0.001). Moreover, τ_PCr correlated with the hyperemic BOLD response in the gastrocnemius muscle (r = –0.66; P < 0.01).

Data Conclusion

MR readouts of calf muscle tissue oxygenation and high‐energy phosphate metabolism were acquired essentially simultaneously during a single exercise‐recovery session. A pronounced hypoxia‐triggered vasodilation in PAD is associated with a reduced mitochondrial oxidative capacity.

Level of Evidence: 2

Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:98–107.

Multimodal Positron Emission Tomography Imaging to Quantify Uptake of 89Zr-Labeled Liposomes in the Atherosclerotic Vessel Wall

Nanotherapy has recently emerged as an experimental treatment option for atherosclerosis. To fulfill its promise, robust noninvasive imaging approaches for subject selection and treatment evaluation are warranted. To that end, we present here a positron emission tomography (PET)-based method for quantification of liposomal nanoparticle uptake in the atherosclerotic vessel wall. We evaluated a modular procedure to label liposomal nanoparticles with the radioisotope zirconium-89 (⁸⁹Zr). Their biodistribution and vessel wall targeting in a rabbit atherosclerosis model was evaluated up to 15 days after intravenous injection by PET/computed tomography (CT) and PET/magnetic resonance imaging (PET/MRI). Vascular permeability was assessed in vivo using three-dimensional dynamic contrast-enhanced MRI (3D DCE-MRI) and ex vivo using near-infrared fluorescence (NIRF) imaging. The ⁸⁹Zr-radiolabeled liposomes displayed a biodistribution pattern typical of long-circulating nanoparticles. Importantly, they markedly accumulated in atherosclerotic lesions in the abdominal aorta, as evident on PET/MRI and confirmed by autoradiography, and this uptake moderately correlated with vascular permeability. The method presented herein facilitates the development of nanotherapy for atherosclerotic disease as it provides a tool to screen for nanoparticle targeting in individual subjects' plaques.

N-Glycosylation Defects in Humans Lower Low-Density Lipoprotein Cholesterol Through Increased Low-Density Lipoprotein Receptor Expression

BACKGROUND

The importance of protein glycosylation in regulating lipid metabolism is becoming increasingly apparent. We set out to further investigate this by studying patients with type I congenital disorders of glycosylation (CDGs) with defective N-glycosylation.

METHODS

We studied 29 patients with the 2 most prevalent types of type I CDG, ALG6 (asparagine-linked glycosylation protein 6)-deficiency CDG and PMM2 (phosphomannomutase 2)-deficiency CDG, and 23 first- and second-degree relatives with a heterozygous mutation and measured plasma cholesterol levels. Low-density lipoprotein (LDL) metabolism was studied in 3 cell models-gene silencing in HepG2 cells, patient fibroblasts, and patient hepatocyte-like cells derived from induced pluripotent stem cells-by measuring apolipoprotein B production and secretion, LDL receptor expression and membrane abundance, and LDL particle uptake. Furthermore, SREBP2 (sterol regulatory element-binding protein 2) protein expression and activation and endoplasmic reticulum stress markers were studied.

RESULTS

We report hypobetalipoproteinemia (LDL cholesterol [LDL-C] and apolipoprotein B below the fifth percentile) in a large cohort of patients with type I CDG (mean age, 9 years), together with reduced LDL-C and apolipoprotein B in clinically unaffected heterozygous relatives (mean age, 46 years), compared with 2 separate sets of age- and sex-matched control subjects. ALG6 and PMM2 deficiency led to markedly increased LDL uptake as a result of increased cell surface LDL receptor abundance. Mechanistically, this outcome was driven by increased SREBP2 protein expression accompanied by amplified target gene expression, resulting in higher LDL receptor protein levels. Endoplasmic reticulum stress was not found to be a major mediator.

CONCLUSIONS

Our study establishes N-glycosylation as an important regulator of LDL metabolism. Given that LDL-C was also reduced in a group of clinically unaffected heterozygotes, we propose that increasing LDL receptor-mediated cholesterol clearance by targeting N-glycosylation in the LDL pathway may represent a novel therapeutic strategy to reduce LDL-C and cardiovascular disease.

A 3-SNP gene risk score and a metabolic risk score both predict hypertriglyceridemia and cardiovascular disease risk

BACKGROUND

Evidence on the causal link between plasma triglyceride (TG) levels and risk for cardiovascular disease (CVD) has recently emerged. Individuals with the metabolic syndrome have an increased risk for acquiring elevated TG levels later in life. Moreover, common DNA sequence variations in genes affecting TG levels identify individuals at risk for elevated plasma TG levels.

OBJECTIVE

We evaluated whether a 3-single nucleotide polymorphism (SNP) TG gene risk score (GRS) and a metabolic risk score (MetRS) both improved CVD risk prediction.

METHODS

A 3-SNP GRS and MetRS were generated in the EPIC-Norfolk cohort (n = 20,074) based on 3 SNPs in LPL and APOA5 or the number of Metabolic Syndrome criteria present (maximum 5), respectively. The associations between the 3-SNP GRS, MetRS, TG levels, and CVD risk were evaluated.

RESULTS

The 3-SNP GRS and MetRS were both linearly associated with plasma TG levels, that is, +0.25 mmol/L [95% CI 0.22-0.27] per allele change (P < .001) and +0.72 mmol/L [95% CI 0.70-0.73] per increase of number of metabolic syndrome risk score points (P < .001), respectively. We observed a positive association between the 3-SNP GRS and the risk of CVD with an adjusted hazard ratio (HR) of 1.35 [95% CI 1.04-1.74] for the highest versus the lowest GRS, which was independent of the MetRS. For the MetRS, the adjusted HR was 2.03 [95% CI 1.73-2.40] for the highest versus the lowest MetRS.

CONCLUSION

Both the 3-SNP GRS and the MetRS are associated with increased plasma TG levels and increased risk for CVD.

Predictive value of targeted proteomics for coronary plaque morphology in patients with suspected coronary artery disease

Background

Risk stratification is crucial to improve tailored therapy in patients with suspected coronary artery disease (CAD). This study investigated the ability of targeted proteomics to predict presence of high-risk plaque or absence of coronary atherosclerosis in patients with suspected CAD, defined by coronary computed tomography angiography (CCTA).

Methods

Patients with suspected CAD (n = 203) underwent CCTA. Plasma levels of 358 proteins were used to generate machine learning models for the presence of CCTA-defined high-risk plaques or complete absence of coronary atherosclerosis. Performance was tested against a clinical model containing generally available clinical characteristics and conventional biomarkers.

Findings

A total of 196 patients with analyzable protein levels (n = 332) was included for analysis. A subset of 35 proteins was identified predicting the presence of high-risk plaques. The developed machine learning model had fair diagnostic performance with an area under the curve (AUC) of 0·79 ± 0·01, outperforming prediction with generally available clinical characteristics (AUC = 0·65 ± 0·04, p < 0·05). Conversely, a different subset of 34 proteins was predictive for the absence of CAD (AUC = 0·85 ± 0·05), again outperforming prediction with generally available characteristics (AUC = 0·70 ± 0·04, p < 0·05).

Interpretation

Using machine learning models, trained on targeted proteomics, we defined two complementary protein signatures: one for identification of patients with high-risk plaques and one for identification of patients with absence of CAD. Both biomarker subsets were superior to generally available clinical characteristics and conventional biomarkers in predicting presence of high-risk plaque or absence of coronary atherosclerosis. These promising findings warrant external validation of the value of targeted proteomics to identify cardiovascular risk in outcome studies.

Fund

This study was supported by an unrestricted research grant from HeartFlow Inc. and partly supported by a European Research Area Network on Cardiovascular Diseases (ERA-CVD) grant (ERA CVD JTC2017, OPERATION). Funders had no influence on trial design, data evaluation, and interpretation.

Sympathetic activation by lower body negative pressure decreases kidney perfusion without inducing hypoxia in healthy humans

Purpose

There is ample evidence that systemic sympathetic neural activity contributes to the progression of chronic kidney disease, possibly by limiting renal blood flow and thereby inducing renal hypoxia. Up to now there have been no direct observations of this mechanism in humans. We studied the effects of systemic sympathetic activation elicited by a lower body negative pressure (LBNP) on renal blood flow (RBF) and renal oxygenation in healthy humans.

Methods

Eight healthy volunteers (age 19–31 years) were subjected to progressive LBNP at − 15 and − 30 mmHg, 15 min per level. Brachial artery blood pressure was monitored intermittently. RBF was measured by phase-contrast MRI in the proximal renal artery. Renal vascular resistance was calculated as the MAP divided by the RBF. Renal oxygenation (R2*) was measured for the cortex and medulla by blood oxygen level dependent (BOLD) MRI, using a monoexponential fit.

Results

With a LBNP of − 30 mmHg, pulse pressure decreased from 50 ± 10 to 43 ± 7 mmHg; MAP did not change. RBF decreased from 1152 ± 80 to 1038 ± 83 mL/min to 950 ± 67 mL/min at − 30 mmHg LBNP (p = 0.013). Heart rate and renal vascular resistance increased by 38 ± 15% and 23 ± 8% (p = 0.04) at − 30 mmHg LBNP, respectively. There was no change in cortical or medullary R2* (20.3 ± 1.2 s⁻¹ vs 19.8 ± 0.43 s⁻¹; 28.6 ± 1.1 s⁻¹ vs 28.0 ± 1.3 s⁻¹).

Conclusion

The results suggest that an increase in sympathetic vasoconstrictor drive decreases kidney perfusion without a parallel reduction in oxygenation in healthy humans. This in turn indicates that sympathetic activation suppresses renal oxygen demand and supply equally, thus allowing adequate tissue oxygenation to be maintained.

Monocyte and haematopoietic progenitor reprogramming as common mechanism underlying chronic inflammatory and cardiovascular diseases

A large number of cardiovascular events are not prevented by current therapeutic regimens. In search for additional, innovative strategies, immune cells have been recognized as key players contributing to atherosclerotic plaque progression and destabilization. Particularly the role of innate immune cells is of major interest, following the recent paradigm shift that innate immunity, long considered to be incapable of learning, does exhibit immunological memory mediated via epigenetic reprogramming. Compelling evidence shows that atherosclerotic risk factors promote immune cell migration by pre-activation of circulating innate immune cells. Innate immune cell activation via metabolic and epigenetic reprogramming perpetuates a systemic low-grade inflammatory state in cardiovascular disease (CVD) that is also common in other chronic inflammatory disorders. This opens a new therapeutic area in which metabolic or epigenetic modulation of innate immune cells may result in decreased systemic chronic inflammation, alleviating CVD, and its co-morbidities.

Relationship of lipoprotein-associated apolipoprotein C-III with lipid variables and coronary artery disease risk: The EPIC-Norfolk prospective population study

BACKGROUND

Plasma apolipoprotein C-III (apoC-III) levels are associated with coronary artery disease (CAD) risk.

OBJECTIVE

To assess whether lipoprotein-associated apoC-III levels predict risk of CAD events.

METHODS

apoC-III associated with apoB, apoAI, and Lp(a) (apoCIII-apoB, apoCIII-apoAI, and apoCIII-Lp(a), respectively) were measured using high-throughput chemiluminescent enzyme-linked immunoassays in 2711 subjects (1879 controls and 832 cases with CAD) in the European Prospective Investigation into Cancer and Nutrition-Norfolk prospective population study with 7.4 years of follow-up. These measures were correlated with a variety of lipid measurements and the presence of CAD. The indices of "total apoCIII-apoB" and "total apoCIII-apoAI" were derived by multiplying plasma apoB and apoAI, respectively.

RESULTS

apoCIII-apoB (P = .001), apoCIII-Lp(a) (P < .001), apoCIII-apoAI (P = .005) were higher in cases vs controls; tended to correlate positively with body mass index, hsCRP, apoC-III, low-density lipoprotein (LDL) cholesterol, triglycerides, remnant cholesterol, very low density lipoprotein, LDL and high-density lipoprotein particle number and very low density lipoprotein size; but negatively with LDL and high-density lipoprotein particle size (P < .001 for all). apoCIII-apoB, apoCIII-apoAI, apoCIII-Lp(a), total apoCIII-Lp(a), and total apoCIII-apoB were predictors of CAD after adjustment of age, sex, body mass index, smoking, diabetes, hypertensive and lipid-lowering drug use, but they lost their significance after further adjustment of lipid and lipoprotein variables.

CONCLUSIONS

This study suggests that enzyme-linked immunoassay-measured lipoprotein-associated apoC-III markers reflect atherogenic lipid particles but do not independently predict risk of CAD events.

Author Correction: Efficacy and safety assessment of a TRAF6-targeted nanoimmunotherapy in atherosclerotic mice and non-human primates

In the version of this Article originally published, the surname of the author Edward A. Fisher was spelt incorrectly as 'Fischer'. This has now been corrected.

Sympathetic Neuronal Activation Triggers Myeloid Progenitor Proliferation and Differentiation

There is a growing body of research on the neural control of immunity and inflammation. However, it is not known whether the nervous system can regulate the production of inflammatory myeloid cells from hematopoietic progenitor cells in disease conditions. Myeloid cell numbers in diabetic patients were strongly correlated with plasma concentrations of norepinephrine, suggesting the role of sympathetic neuronal activation in myeloid cell production. The spleens of diabetic patients and mice contained higher numbers of tyrosine hydroxylase (TH)-expressing leukocytes that produced catecholamines. Granulocyte macrophage progenitors (GMPs) expressed the β2 adrenergic receptor, a target of catecholamines. Ablation of splenic sympathetic neuronal signaling using surgical, chemical, and genetic approaches diminished GMP proliferation and myeloid cell development. Finally, mice lacking TH-producing leukocytes had reduced GMP proliferation, resulting in diminished myelopoiesis. Taken together, our study demonstrates that catecholamines produced by leukocytes and sympathetic nerve termini promote GMP proliferation and myeloid cell development.

Cardiovascular disease risk associated with elevated lipoprotein(a) attenuates at low low-density lipoprotein cholesterol levels in a primary prevention setting

Aims

Lipoprotein(a) (Lp(a)) elevation is a causal risk factor for cardiovascular disease (CVD). It has however been suggested that elevated Lp(a) causes CVD mainly in individuals with high low-density lipoprotein cholesterol (LDL-C) levels. We hypothesized that the risk associated with high Lp(a) levels would largely be attenuated at low LDL-C levels.

Methods and results

In 16 654 individuals from the EPIC-Norfolk prospective population study, and in 9448 individuals from the Copenhagen City Heart Study (CCHS) parallel statistical analyses were performed. Individuals were categorized according to their Lp(a) and LDL-C levels. Cut-offs were set at the 80th cohort percentile for Lp(a). Low-density lipoprotein cholesterol cut-offs were set at 2.5, 3.5, 4.5, and 5.5 mmol/L. Low-density lipoprotein cholesterol levels in the primary analyses were corrected for Lp(a)-derived LDL-C (LDL-Ccorr). Multivariable-adjusted hazard ratios were calculated for each category. The category with LDL-Ccorr <2.5 mmol/L and Lp(a) <80th cohort percentile was used as reference category. In the EPIC-Norfolk and CCHS cohorts, individuals with an Lp(a) ≥80th percentile were at increased CVD risk compared with those with Lp(a) <80th percentile for any LDL-Ccorr levels ≥2.5 mmol/L. In contrast, for LDL-Ccorr <2.5 mmol/L, the risk associated with elevated Lp(a) attenuated. However, there was no interaction between LDL-Ccorr and Lp(a) levels on CVD risk in either cohort.

Conclusion

Lipoprotein(a) and LDL-C are independently associated with CVD risk. At LDL-C levels below <2.5 mmol/L, the risk associated with elevated Lp(a) attenuates in a primary prevention setting.

Efficacy and safety assessment of a TRAF6-targeted nanoimmunotherapy in atherosclerotic mice and non-human primates

Macrophage accumulation in atherosclerosis is directly linked to the destabilization and rupture of plaque, causing acute atherothrombotic events. Circulating monocytes enter the plaque and differentiate into macrophages, where they are activated by CD4+ T lymphocytes through CD40-CD40 ligand signalling. Here, we report the development and multiparametric evaluation of a nanoimmunotherapy that moderates CD40-CD40 ligand signalling in monocytes and macrophages by blocking the interaction between CD40 and tumour necrosis factor receptor-associated factor 6 (TRAF6). We evaluated the biodistribution characteristics of the nanoimmunotherapy in apolipoprotein E-deficient (Apoe-/-) mice and in non-human primates by in vivo positron-emission tomography imaging. In Apoe-/- mice, a 1-week nanoimmunotherapy treatment regimen achieved significant anti-inflammatory effects, which was due to the impaired migration capacity of monocytes, as established by a transcriptome analysis. The rapid reduction of plaque inflammation by the TRAF6-targeted nanoimmunotherapy and its favourable toxicity profiles in both mice and non-human primates highlights the translational potential of this strategy for the treatment of atherosclerosis.

Effect of Vegan Fecal Microbiota Transplantation on Carnitine- and Choline-Derived Trimethylamine-N-Oxide Production and Vascular Inflammation in Patients With Metabolic Syndrome

BACKGROUND

Intestinal microbiota have been found to be linked to cardiovascular disease via conversion of the dietary compounds choline and carnitine to the atherogenic metabolite TMAO (trimethylamine-N-oxide). Specifically, a vegan diet was associated with decreased plasma TMAO levels and nearly absent TMAO production on carnitine challenge.

METHODS AND RESULTS

We performed a double-blind randomized controlled pilot study in which 20 male metabolic syndrome patients were randomized to single lean vegan-donor or autologous fecal microbiota transplantation. At baseline and 2 weeks thereafter, we determined the ability to produce TMAO from d6-choline and d3-carnitine (eg, labeled and unlabeled TMAO in plasma and 24-hour urine after oral ingestion of 250 mg of both isotope-labeled precursor nutrients), and fecal samples were collected for analysis of microbiota composition. 18F-fluorodeoxyglucose positron emission tomography/computed tomography scans of the abdominal aorta, as well as ex vivo peripheral blood mononuclear cell cytokine production assays, were performed. At baseline, fecal microbiota composition differed significantly between vegans and metabolic syndrome patients. With vegan-donor fecal microbiota transplantation, intestinal microbiota composition in metabolic syndrome patients, as monitored by global fecal microbial community structure, changed toward a vegan profile in some of the patients; however, no functional effects from vegan-donor fecal microbiota transplantation were seen on TMAO production, abdominal aortic 18F-fluorodeoxyglucose uptake, or ex vivo cytokine production from peripheral blood mononuclear cells.

CONCLUSIONS

Single lean vegan-donor fecal microbiota transplantation in metabolic syndrome patients resulted in detectable changes in intestinal microbiota composition but failed to elicit changes in TMAO production capacity or parameters related to vascular inflammation.

CLINICAL TRIAL REGISTRATION

URL: http://www.trialregister.nl. Unique identifier: NTR 4338.

Inflammation-Sensitive Myosin-X Functionally Supports Leukocyte Extravasation by Cdc42-Mediated ICAM-1-Rich Endothelial Filopodia Formation

Leukocyte transendothelial migration is key to inflammation. Leukocytes first start rolling over the inflamed endothelium, followed by firmly adhering to it. Under inflammatory conditions, endothelial cells express small finger-like protrusions that stick out into the lumen. The function and regulation of these structures are unclear. We present evidence that these ICAM-1- and F-actin-rich endothelial finger-like protrusions are filopodia and function as adhesive structures for leukocytes to transit from rolling to crawling but are dispensable for diapedesis. Mechanistically, these structures require the motor function of myosin-X, activity of the small GTPase Cdc42, and p21-activated kinase 4. Moreover, myosin-X expression is under control of TNF-α-mediated c-Jun N-terminal kinase activity and is upregulated in human atherosclerotic regions. To our knowledge, this is the first study to identify that regulation of endothelial filopodia is crucial for leukocyte extravasation, in particular for the initiation of leukocyte adhesion under flow conditions.

Increased haematopoietic activity in patients with atherosclerosis

Aims

Experimental work posits that acute ischaemic events trigger haematopoietic activity, driving monocytosis, and atherogenesis. Considering the chronic low-grade inflammatory state in atherosclerosis, we hypothesized that haematopoietic hyperactivity is a persistent feature in cardiovascular disease (CVD). Therefore, we aimed to assess the activity of haematopoietic organs and haematopoietic stem and progenitor cells (HSPCs) in humans.

Methods and results

First, we performed 18F-fluorodeoxyglucose positron emission tomographic (18F-FDG PET) imaging in 26 patients with stable atherosclerotic CVD (ischaemic event >12 months ago), and 25 matched controls. In splenic tissue, 18F-FDG uptake was 2.68 ± 0.65 in CVD patients vs. 1.75 ± 0.54 in controls (1.6-fold higher; P< 0.001), and in bone marrow 3.20 ± 0.76 vs. 2.72 ± 0.46 (1.2-fold higher; P = 0.003), closely related to LDL cholesterol levels (LDLc, r = 0.72). Subsequently, we determined progenitor potential of HSPCs harvested from 18 patients with known atherosclerotic CVD and 30 matched controls; both groups were selected from a cohort of cancer patients undergoing autologous stem cell transplantation. In CVD patients, the normalized progenitor potential, expressed as the number of colony-forming units-granulocyte/monocyte (CFU-GM) colonies/CD34+ cell, was 1.6-fold higher compared with matched controls (P < 0.001). Finally, we assessed the effects of native and oxidized lipoproteins on HSPCs harvested from healthy donors in vitro. Haematopoietic stem and progenitor cells displayed a 1.5-fold increased CFU-GM capacity in co-culture with oxidized LDL in vitro (P = 0.002), which was inhibited by blocking oxidized phospholipids via E06 (P = 0.001).

Conclusion

Collectively, these findings strengthen the case for a chronically affected haematopoietic system, potentially driving the low-grade inflammatory state in patients with atherosclerosis.

The maturation of a 'neural-hematopoietic' inflammatory axis in cardiovascular disease

PURPOSE OF REVIEW

Atherogenesis is the result of a complex interplay between lipids and innate immune cells, which are descendants of upstream progenitors residing in hematopoietic organs. In this review, we will discuss recent advances in the connection between hematopoiesis and atherogenesis.

RECENT FINDINGS

The relevance of a neural-hematopoietic axis was recently supported by the demonstration of a correlation between metabolic activity in the amygdala and the bone marrow. During follow-up, both amygdalar and bone marrow activities also predicted cardiovascular risk in patients, lending further support to a connection between neural stress and cardiovascular events mediated via increased hematopoietic activity.In parallel, functional changes in hematopoietic stem cells may also convey cardiovascular risk. In experimental models, knock-out of the ten-eleven translocation 2 (TET2) gene leading to monocyte-macrophage hyperresponsiveness, was associated with accelerated atherogenesis in murine experiments. In humans, whole-exome sequencing reporting on the 'clonal hematopoiesis of indeterminate potential' gene substantiated a two-fold elevated risk for developing coronary heart disease compared with noncarriers.

SUMMARY

Recent studies support the relevance of a 'neural-hematopoietic' inflammatory axis and clonal hematopoiesis as drivers of atherogenesis in humans. These data warrant further studies addressing the role of novel 'hematopoietic' targets for the treatment of patients with increased cardiovascular risk.

Intestinal Ralstonia pickettii augments glucose intolerance in obesity

An altered intestinal microbiota composition has been implicated in the pathogenesis of metabolic disease including obesity and type 2 diabetes mellitus (T2DM). Low grade inflammation, potentially initiated by the intestinal microbiota, has been suggested to be a driving force in the development of insulin resistance in obesity. Here, we report that bacterial DNA is present in mesenteric adipose tissue of obese but otherwise healthy human subjects. Pyrosequencing of bacterial 16S rRNA genes revealed that DNA from the Gram-negative species Ralstonia was most prevalent. Interestingly, fecal abundance of Ralstonia pickettii was increased in obese subjects with pre-diabetes and T2DM. To assess if R. pickettii was causally involved in development of obesity and T2DM, we performed a proof-of-concept study in diet-induced obese (DIO) mice. Compared to vehicle-treated control mice, R. pickettii-treated DIO mice had reduced glucose tolerance. In addition, circulating levels of endotoxin were increased in R. pickettii-treated mice. In conclusion, this study suggests that intestinal Ralstonia is increased in obese human subjects with T2DM and reciprocally worsens glucose tolerance in DIO mice.

Omega-3 carboxylic acids in patients with severe hypertriglyceridemia: EVOLVE II, a randomized, placebo-controlled trial

BACKGROUND

Adult patients with severe hypertriglyceridemia (SHTG) are at increased risk of developing acute pancreatitis and cardiovascular disease. Omega-3 carboxylic acids (OM3-CA) are approved for treatment as an adjunct to diet to reduce triglyceride (TG) concentrations in patients with SHTG.

OBJECTIVE

The aim of the study was to assess efficacy and safety of the intermediate dose of OM3-CA (2 g daily), compared with olive oil 2 g daily, in reducing serum TG and lipid concentrations in patients with SHTG.

METHODS

A randomized, double-blind, olive oil-controlled, parallel-group trial involving 162 adults with qualifying serum TG concentrations of at least 500 mg/dL (5.65 mmol/L) and <2500 mg/dL (28.25 mmol/L; <2000 mg/dL [22.60 mmol/L] in Canada). The treatment period after randomization was 12 weeks. Blood samples for measurement of fasting serum lipid concentrations were taken at baseline, 6, 10, and 12 weeks.

RESULTS

Treatment with OM3-CA 2 g daily led to a significant reduction in TG concentrations (median of differences, -14.2% [95% confidence interval: -26.2%, -2.8%; P = .017]) and non-high-density lipoprotein cholesterol concentrations (median of differences, -9.0% [95% confidence interval: -14.8%, -2.8%; adjusted P = .018]) from baseline to the Week 12 endpoint, when compared with olive oil 2 g daily. These treatment effects were more pronounced in patients with qualifying TG concentrations >885 mg/dL (10 mmol/L).

CONCLUSION

An intermediate dose of OM3-CA (2 g daily) significantly lowers TG and non-high-density lipoprotein cholesterol concentrations in patients with SHTG and may benefit individuals at risk of acute pancreatitis and cardiovascular disease.

Characterization of immune cell, endothelial, and renal responses upon experimental human endotoxemia

INTRODUCTION

Although the effects of relatively high concentrations of endotoxin on endothelial activation/dysfunction and kidney markers has been described in literature, detailed insight in the LPS concentration-effect relationship, the magnitude, variability and timing of the response, and potential effects of endotoxemia on the kidneys is lacking. A study was performed to assess the effects of low- to moderate dose (0.5, 1 or 2ng/kg) endotoxemia on the endothelium and kidneys as measured by a panel of novel highly sensitive kidney injury markers.

METHODS

This was a randomized, double-blind, placebo-controlled study with single ascending doses of LPS (0.5, 1 or 2ng/kg) administered to healthy male volunteers (3 cohorts of 8 subjects, LPS:placebo 6:2). Endothelial measures included selectins, cell adhesion molecules, and thrombomodulin. Renal measures included novel, sensitive and specific biomarkers of acute kidney injury.

RESULTS

Endotoxin exposure resulted in consistent LPS dose-dependent responses in inflammatory markers, E- and P- Selectin, VCAM1, ICAM1, and thrombomodulin. The observed biological responses were transient, reaching a level of significance of at least <0.01 in the highest dose group and with an effect size which was dependent on the administered LPS dose. LPS-induced inflammatory and endothelial effects did not translate into a change in renal damage biomarkers, although at 2ng/kg LPS, subtle and transient biomarker changes were observed that may relate to (subclinical) tubular damage.

DISCUSSION

We demonstrated that administration of a single LPS dose of 2ng/kg to healthy volunteers results in significant inflammatory and endothelial responses, without inducing clinically relevant signs of kidney injury. These findings support the application of the human endotoxemia model in future clinical pharmacology studies.