The effect of low-dose proteasome inhibition on pre-existing atherosclerosis in LDL receptor-deficient mice

Dysfunction of the ubiquitin-proteasome system (UPS) has been implicated in atherosclerosis development. However, the nature of UPS dysfunction has been proposed to be specific to certain stages of atherosclerosis development, which has implications for proteasome inhibition as a potential treatment option. Recently, low-dose proteasome inhibition with bortezomib has been shown to attenuate early atherosclerosis in low-density lipoprotein receptor-deficient (LDLR(-/-)) mice. The present study investigates the effect of low-dose proteasome inhibition with bortezomib on pre-existing advanced atherosclerosis in LDLR(-/-) mice. We found that bortezomib treatment of LDLR(-/-) mice with pre-existing atherosclerosis does not alter lesion burden. Additionally, macrophage infiltration of aortic root plaques, total plasma cholesterol levels, and pro-inflammatory serum markers were not influenced by bortezomib. However, plaques of bortezomib-treated mice exhibited larger necrotic core areas and a significant thinning of the fibrous cap, indicating a more unstable plaque phenotype. Taking recent studies on favorable effects of proteasome inhibition in early atherogenesis into consideration, our data support the hypothesis of stage-dependent effects of proteasome inhibition in atherosclerosis

Effect of a probiotic on blood pressure in grade 1 hypertension (HYPRO): protocol of a randomized controlled study

BACKGROUND: Arterial hypertension is a major risk factor for cardiovascular disease and leads to target organ damage including stroke, heart failure, and kidney disease. About 1.5 billion people worldwide have hypertension, and it is estimated that it causes about 8 million deaths each year. Although there are several drugs available to lower blood pressure (BP), a great proportion of treated patients does not reach recommended treatment targets. Typical antihypertensive drugs target the vessels, the kidneys, and the heart. However, our gut microbiota also influences cardiovascular health, and gut dysbiosis is associated with hypertension. In this study protocol, we investigate the potential BP-lowering effect of a probiotic in patients with grade 1 hypertension. METHODS: This study is an exploratory, randomized, double-blind, placebo-controlled, parallel-group study. One hundred ten patients with grade 1 hypertension (treated or untreated) will be randomized to either the probiotic Vivomixx® or placebo. The primary endpoint is the nocturnal systolic BP measured by ambulatory blood pressure monitoring after 8 weeks adjusted for the baseline value. The secondary endpoints are changes from baseline in nocturnal diastolic BP, antihypertensive medication, fecal microbiome composition, fecal and serum metabolome, immune cell phenotypes, glucose variability after three standardized breakfasts, and health-related quality of life (PROMIS-29). We also assess the safety profile of the intervention. DISCUSSION: We postulate that various administrated bacteria (Lactobacilli, Bifidobacteria, and Streptococcus thermophilus) convert dietary components into active metabolites that positively affect immune cell function. A reduction of pro-inflammatory immune cell function could promote a BP-lowering effect. TRIAL REGISTRATION: ClinicalTrials.gov NCT03906578 . Registered on 08 April 2019

The role of the gut microbiota and microbial metabolites in neuroinflammation

Recent literature indicates a potential importance of the gut microbiota for immune mediated diseases. For instance, decreased diversity of commensals or an outgrowth of some bacterial strains, referred to as gut dysbiosis, was recently linked to hypertension, colitis, lupus, rheumatoid arthritis and multiple sclerosis (MS). Studies in experimental autoimmune encephalomyelitis (EAE) as pivotal animal model of MS revealed a potential importance of microbial metabolites, including short-chain fatty acids or tryptophan metabolites. Both metabolites may influence the disease by modulation of the immune system, mainly by inducing regulatory T cells. These studies prompted researchers to investigate the contribution of the gut microbiota and microbial metabolites in the pathogenesis of MS. This review summarizes recent findings on the gut microbiota in MS patients and discusses the potential mechanisms how microbial metabolites may affect neuroinflammation. Many of these studies have been performed in the EAE model and were later reversely translated to humans. We also give a short summary on dietary high-salt effects on microbiota components and discuss the potential relevance of high-salt as a risk factor in MS. This article is protected by copyright. All rights reserved

Bacterial metabolites and cardiovascular risk in children with chronic kidney disease

Cardiovascular complications are the major cause of the marked morbidity and mortality associated with chronic kidney disease (CKD). The classical cardiovascular risk factors such as diabetes and hypertension undoubtedly play a role in the development of cardiovascular disease (CVD) in adult CKD patients; however, CVD is just as prominent in children with CKD who do not have these risk factors. Hence, the CKD-specific pathophysiology of CVD remains incompletely understood. In light of this, studying children with CKD presents a unique opportunity to analyze CKD-associated mechanisms of CVD more specifically and could help to unveil novel therapeutic targets.Here, we comprehensively review the interaction of the human gut microbiome and the microbial metabolism of nutrients with host immunity and cardiovascular end-organ damage. The human gut microbiome is evolutionary conditioned and modified throughout life by endogenous factors as well as environmental factors. Chronic diseases, such as CKD, cause significant disruption to the composition and function of the gut microbiome and lead to disease-associated dysbiosis. This dysbiosis and the accompanying loss of biochemical homeostasis in the epithelial cells of the colon can be the result of poor diet (e.g., low-fiber intake), medications, and underlying disease. As a result of dysbiosis, bacteria promoting proteolytic fermentation increase and those for saccharolytic fermentation decrease and the integrity of the gut barrier is perturbed (leaky gut). These changes disrupt local metabolite homeostasis in the gut and decrease productions of the beneficial short-chain fatty acids (SCFAs). Moreover, the enhanced proteolytic fermentation generates unhealthy levels of microbially derived toxic metabolites, which further accumulate in the systemic circulation as a consequence of impaired kidney function. We describe possible mechanisms involved in the increased systemic inflammation in CKD that is associated with the combined effect of SCFA deficiency and accumulation of uremic toxins. In the future, a more comprehensive and mechanistic understanding of the gut-kidney-heart interaction, mediated largely by immune dysregulation and inflammation, might allow us to target the gut microbiome more specifically in order to attenuate CKD-associated comorbidities

Increased salt intake decreases diet-induced thermogenesis in healthy volunteers: a randomized placebo-controlled study

High salt intake ranks among the most important risk factors for noncommunicable diseases. Western diets, which are typically high in salt, are associated with a high prevalence of obesity. High salt is thought to be a potential risk factor for obesity independent of energy intake, although the underlying mechanisms are insufficiently understood. A high salt diet could influence energy expenditure (EE), specifically diet-induced thermogenesis (DIT), which accounts for about 10% of total EE. We aimed to investigate the influence of high salt on DIT. In a randomized, double-blind, placebo-controlled, parallel-group study, 40 healthy subjects received either 6 g/d salt (NaCl) or placebo in capsules over 2 weeks. Before and after the intervention, resting EE, DIT, body composition, food intake, 24 h urine analysis, and blood pressure were obtained. EE was measured by indirect calorimetry after a 12 h overnight fast and a standardized 440 kcal meal. Thirty-eight subjects completed the study. Salt intake from foods was 6 g/d in both groups, resulting in a total salt intake of 12 g/d in the salt group and 6 g/d in the placebo group. Urine sodium increased by 2.29 g/d (p < 0.0001) in the salt group, indicating overall compliance. The change in DIT differed significantly between groups (placebo vs. salt, p = 0.023). DIT decreased by 1.3% in the salt group (p = 0.048), but increased by 0.6% in the placebo group (NS). Substrate oxidation indicated by respiratory exchange ratio, body composition, resting blood pressure, fluid intake, hydration, and urine volume did not change significantly in either group. A moderate short-term increase in salt intake decreased DIT after a standardized meal. This effect could at least partially contribute to the observed weight gain in populations consuming a Western diet high in salt

Short-chain fatty acid propionate protects from hypertensive cardiovascular damage

BACKGROUND: Arterial hypertension and its organ sequelae show characteristics of T cell mediated inflammatory diseases. Experimental anti-inflammatory therapies have been shown to ameliorate hypertensive end-organ damage. Recently, the CANTOS study targeting interleukin-1β demonstrated that anti-inflammatory therapy reduces cardiovascular risk. The gut microbiome plays pivotal role in immune homeostasis and cardiovascular health. Short-chain fatty acids (SCFA) are produced from dietary fiber by gut bacteria and affect host immune homeostasis. Here, we investigated effects of the SCFA propionate in two different mouse models of hypertensive cardiovascular damage. METHODS: To investigate the effect of SCFA on hypertensive cardiac damage and atherosclerosis, wild-type NMRI (WT) or ApoE(-/-) deficient mice received propionate (200mM) or control in the drinking water. To induce hypertension, WT mice were infused with Angiotensin (Ang)II (1.44mg/kg/d s.c.) for 14 days. To accelerate the development of atherosclerosis, ApoE(-/-) mice were infused with AngII (0.72mg/kg/d s.c.) for 28 days. Cardiac damage and atherosclerosis were assessed using histology, echocardiography, in vivo electrophysiology, immunofluorescence, and flow cytometry. Blood pressure was measured by radiotelemetry. Regulatory T cell (Treg) depletion using PC61 antibody was used to examine the mode of action of propionate. RESULTS: Propionate significantly attenuated cardiac hypertrophy, fibrosis, vascular dysfunction, and hypertension in both models. Susceptibility to cardiac ventricular arrhythmias was significantly reduced in propionate-treated AngII-infused WT mice. Aortic atherosclerotic lesion area was significantly decreased in propionate-treated ApoE(-/-). Systemic inflammation was mitigated by propionate treatment, quantified as a reduction in splenic effector memory T cell frequencies and splenic T helper 17 cells in both models, and a decrease in local cardiac immune cell infiltration in WT mice. Cardioprotective effects of propionate were abrogated in Treg-depleted AngII-infused mice, suggesting the effect is Treg-dependent. CONCLUSIONS: Our data emphasize an immune-modulatory role of SCFAs and their importance for cardiovascular health. The data suggest that lifestyle modifications leading to augmented SCFA production could be a beneficial non-pharmacological preventive strategy for patients with hypertensive cardiovascular disease

Safety and Immunogenicity of an HIV Adenoviral Vector Boost after DNA Plasmid Vaccine Prime by Route of Administration: A Randomized Clinical Trial

In the development of HIV vaccines, improving immunogenicity while maintaining safety is critical. Route of administration can be an important factor.This multicenter, open-label, randomized trial, HVTN 069, compared routes of administration on safety and immunogenicity of a DNA vaccine prime given intramuscularly at 0, 1 and 2 months and a recombinant replication-defective adenovirus type 5 (rAd5) vaccine boost given at 6 months by intramuscular (IM), intradermal (ID), or subcutaneous (SC) route. Randomization was computer-generated by a central data management center; participants and staff were not blinded to group assignment. The outcomes were vaccine reactogenicity and humoral and cellular immunogenicity. Ninety healthy, HIV-1 uninfected adults in the US and Peru, aged 18-50 were enrolled and randomized. Due to the results of the Step Study, injections with rAd5 vaccine were halted; thus 61 received the booster dose of rAd5 vaccine (IM: 20; ID:21; SC:20). After the rAd5 boost, significant differences by study arm were found in severity of headache, pain and erythema/induration. Immune responses (binding and neutralizing antibodies, IFN-γ ELISpot HIV-specific responses and CD4+ and CD8+ T-cell responses by ICS) at four weeks after the rAd5 booster were not significantly different by administration route of the rAd5 vaccine boost (Binding antibody responses: IM: 66.7%; ID: 70.0%; SC: 77.8%; neutralizing antibody responses: IM: 11.1%; ID: 0.0%; SC 16.7%; ELISpot responses: IM: 46.7%; ID: 35.3%; SC: 44.4%; CD4+ T-cell responses: IM: 29.4%; ID: 20.0%; SC: 35.3%; CD8+ T-cell responses: IM: 29.4%; ID: 16.7%; SC: 50.0%.)This study was limited by the reduced sample size. The higher frequency of local reactions after ID and SC administration and the lack of sufficient evidence to show that there were any differences in immunogenicity by route of administration do not support changing route of administration for the rAd5 boost.ClinicalTrials.gov NCT00384787

Salt transiently inhibits mitochondrial energetics in mononuclear phagocytes

BACKGROUND: Dietary high salt (HS) is a leading risk factor for mortality and morbidity. Serum sodium transiently increases postprandially, but can also accumulate at sites of inflammation affecting differentiation and function of innate and adaptive immune cells. Here, we focus on how changes in extracellular sodium, mimicking alterations in the circulation and tissues, affect the early metabolic, transcriptional and functional adaption of human and murine mononuclear phagocytes (MNP). METHODS: Using Seahorse technology, pulsed stable isotope-resolved metabolomics and enzyme activity assays we characterize the central carbon metabolism and mitochondrial function of human and murine MNP under HS in vitro. HS as well as pharmacologic uncoupling of the electron transport chain (ETC) under normal salt (NS) is used to analyze mitochondrial function on immune cell activation and function (as determined by E.coli killing and CD4(+) T cell migration capacity). In two independent clinical studies we analyze the impact of a HS diet over two weeks (NCT02509962) and short-term salt challenge by a single meal (NCT04175249) on mitochondrial function of human monocytes in vivo. RESULTS: Extracellular sodium was taken up into the intracellular compartment followed by the inhibition of mitochondrial respiration in murine and human macrophages (MΦ). Mechanistically, HS reduces mitochondrial membrane potential, ETC complex II activity, oxygen consumption, and ATP production independently of the polarization status of MΦ. Subsequently, cell activation is altered with improved bactericidal function in HS-treated M1-like MΦ and diminished CD4(+) T cell migration in HS-treated M2-like MΦ. Pharmacologic uncoupling of the ETC under NS phenocopies HS-induced transcriptional changes and bactericidal function of human and murine MNP. Clinically, also in vivo rise in plasma sodium concentration within the physiological range reversibly reduces mitochondrial function in human monocytes. In both, a 14-day and single meal HS challenge, healthy volunteers displayed a plasma sodium increase of ̃x = 2mM and ̃x = 2.3mM, respectively, that correlated with decreased monocytic mitochondrial oxygen consumption. CONCLUSIONS: Our data identify the disturbance of mitochondrial respiration as the initial step by which HS mechanistically influences immune cell function. While these functional changes might help to resolve bacterial infections, a shift towards pro-inflammation could accelerate inflammatory CVD

Quantifying the impact of gut microbiota on inflammation and hypertensive organ damage

AIMS: Hypertension (HTN) can lead to heart and kidney damage. The gut microbiota has been linked to HTN, although it is difficult to estimate its significance due to the variety of other features known to influence HTN. In the present study, we used germ-free (GF) and colonized (COL) littermate mice to quantify the impact of microbial colonization on organ damage in HTN. METHODS AND RESULTS: Four-week-old male GF C57BL/6J littermates were randomized to remain GF or receive microbial colonization. HTN was induced by subcutaneous infusion with angiotensin (Ang) II (1.44 mg/kg/d) and 1% NaCl in the drinking water; sham-treated mice served as control. Renal damage was exacerbated in GF mice, whereas cardiac damage was more comparable between COL and GF, suggesting that the kidney is more sensitive to microbial influence. Multivariate analysis revealed a larger effect of HTN in GF mice. Serum metabolomics demonstrated that the colonization status influences circulating metabolites relevant to HTN. Importantly, GF mice were deficient in anti-inflammatory fecal short-chain fatty acids (SCFA). Flow cytometry showed that the microbiome has an impact on the induction of anti-hypertensive myeloid-derived suppressor cells and pro-inflammatory Th17 cells in HTN. In vitro inducibility of Th17 cells was significantly higher for cells isolated from GF than conventionally raised mice. CONCLUSIONS: Microbial colonization status of mice had potent effects on their phenotypic response to a hypertensive stimulus, and the kidney is a highly microbiota-susceptible target organ in HTN. The magnitude of the pathogenic response in GF mice underscores the role of the microbiome in mediating inflammation in HTN. TRANSLATION PERSPECTIVE: To assess the potential of microbiota-targeted interventions to prevent organ damage in hypertension, an accurate quantification of microbial influence is necessary. We provide evidence that the development of hypertensive organ damage is dependent on colonization status and suggest that a healthy microbiota provides anti-hypertensive immune and metabolic signals to the host. In the absence of normal symbiotic host-microbiome interactions, hypertensive damage to the kidney in particular is exacerbated. We suggest that hypertensive patients experiencing perturbations to the microbiota, which are common in CVD, may be at a greater risk for target-organ damage than those with a healthy microbiome