Which Microbes Like My Diet and What Does It Mean for My Heart?

Cardiovascular diseases are the most common causes of hospitalization, death and disability in Europe. Despite our knowledge of nonmodifiable and modifiable cardiovascular classical risk factors, the morbidity and mortality in this group of diseases remains high, leading to high social and economic costs. Therefore, it is necessary to explore new factors, such as the gut microbiome, that may play a role in many crucial pathological processes related to cardiovascular diseases. Diet is a potentially modifiable cardiovascular risk factor. Fats, proteins, carbohydrates, vitamins and minerals are nutrients that are essential to the proper function of the human body. The style and composition of the human diet has changed over time, evolving from a hunter-gatherer diet to an industrialized and Westernized modern diet that includes processed products. The relationship between the gut microbiome, diet and cardiovascular diseases is complex and still not fully understood. In this review, we discuss, in the context of diet, why particular microbes occur in individuals and how they can influence the host's cardiovascular system in health and disease. We investigate the role of particular microorganisms and changes in the Firmicutes/Bacteroidetes ratio.

The Origin of Plasma-Derived Bacterial Extracellular Vesicles in Healthy Individuals and Patients with Inflammatory Bowel Disease: A Pilot Study.

The gastrointestinal tract harbors the gut microbiota, structural alterations of which (dysbiosis) are linked with an increase in gut permeability ("leaky gut"), enabling luminal antigens and bacterial products such as nanosized bacterial extracellular vesicles (BEVs) to access the circulatory system. Blood-derived BEVs contain various cargoes and may be useful biomarkers for diagnosis and monitoring of disease status and relapse in conditions such as inflammatory bowel disease (IBD). To progress this concept, we developed a rapid, cost-effective protocol to isolate BEV-associated DNA and used 16S rRNA gene sequencing to identify bacterial origins of the blood microbiome of healthy individuals and patients with Crohn's disease and ulcerative colitis. The 16S rRNA gene sequencing successfully identified the origin of plasma-derived BEV DNA. The analysis showed that the blood microbiota richness, diversity, or composition in IBD, healthy control, and protocol control groups were not significantly distinct, highlighting the issue of 'kit-ome' contamination in low-biomass studies. Our pilot study provides the basis for undertaking larger studies to determine the potential use of blood microbiota profiling as a diagnostic aid in IBD.

Effects of probiotics on body adiposity and cardiovascular risk markers in individuals with overweight and obesity: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND & AIMS: Evidence suggests that gut microbiota is a potential factor in the pathophysiology of both obesity and related metabolic disorders. While individual randomized controlled trials (RCTs) have evaluated the effects of probiotics on adiposity and cardiovascular disease (CVD) risk factors in subjects with overweight and obesity, the results are inconsistent. Thus, this systematic review and meta-analysis aimed to evaluate the effects of probiotic supplementation on body weight, body adiposity and CVD risk markers in overweight and obese subjects. METHODS: A systematic search for RCTs published up to December 2020 was conducted in MEDLINE (via PubMed), EMBASE, Scopus and LILACS. Meta-analysis using a random-effects model was chosen to analyze the impact of combined trials. RESULTS: Twenty-six RCTs (n = 1720) were included. Data pooling showed a significant effect of probiotics in reducing body weight (MD:-0.70 kg; 95%CI:-1.04,-0.35 kg; P < 0.0001), body mass index (BMI) (MD:-0.24 kg/m2; 95%CI:-0.35,-0.12 kg/m2; P = 0.0001), waist circumference (WC) (MD:-1.13 cm; 95%CI:-1.54,-0.73 cm; P < 0.0001), fat mass (MD:-0.71 kg; 95%CI:-1.10,-0.32 kg; P = 0.0004), tumor necrosis factor-α (MD:-0.16 pg/ml; 95%CI:-0.24,-0.08 pg/ml; P = 0.0001), insulin (MD:-0.85mcU/ml; 95%CI:-1.50,-0.21mcU/ml; P = 0.010), total cholesterol (MD:-0.16 mmol/l; 95%CI:-0.26,-0.05 mmol/l; P = 0.003) and LDL (MD:-0.09 mmol/l; 95%CI:-0.16,-0.03 mmol/l; P = 0.006) compared with control groups. There was a significant decrease in body weight, BMI and WC in studies using both single and multi-bacterial species. Decreases in body adiposity parameters were only observed in studies using a probiotic dose of ≥ 1010 CFU and for ≥8 weeks duration. CONCLUSIONS: The present meta-analysis suggests that probiotics consumption may be helpful for improving body weight, body adiposity and some CVD risk markers in individuals with overweight and obesity. The review was registered on PROSPERO (International prospective register of systematic reviews): CRD42020183136.

The Impact of Bacterial Biofilms on End-Organ Disease and Mortality in Patients with Hematologic Malignancies Developing a Bloodstream Infection.

Bacterial bloodstream infection (BSI) represents a significant complication in hematologic patients. However, factors leading to BSI and progression to end-organ disease and death are understood only partially. The study analyzes host and microbial risk factors and assesses their impact on BSI development and mortality. A total of 96 patients with hematological malignancies and BSI were included in the study. Host-associated risk factors and all causes of mortality were analyzed by multivariable logistic regression at 30 days after BSI onset of the first neutropenic episode. The multidrug-resistant profile and biofilm production of bacterial isolates from primary BSI were included in the analysis. Median age was 60 years. The underlying diagnoses were acute leukemia (55%), lymphoma (31%), and myeloma (14%). A total of 96 bacterial isolates were isolated from BSIs. Escherichia coli was the most common isolate (29.2%). Multidrug-resistant bacteria caused 10.4% of bacteremia episodes. Weak biofilm producers (WBPs) were significantly (P < 0.0001) more abundant (72.2%) than strong biofilm producers (SBPs) (27.8%). Specifically, SBPs were 7.1% for E. coli, 93.7% for P. aeruginosa, 50% for K. pneumoniae, and 3.8% for coagulase-negative staphylococci. Mortality at day 30 was 8.3%, and all deaths were attributable to Gram-negative bacteria. About 22% of all BSIs were catheter-related BSIs (CRBSIs) and mostly caused by Gram-positive bacteria (79.0%). However, CRBSIs were not correlated with biofilm production levels (P = 0.75) and did not significantly impact the mortality rate (P = 0.62). Conversely, SBP bacteria were an independent risk factor (P = 0.018) for developing an end-organ disease. In addition, multivariate analysis indicated that SBPs (P = 0.013) and multidrug-resistant bacteria (P = 0.006) were independent risk factors associated with 30-day mortality. SBP and multidrug-resistant (MDR) bacteria caused a limited fraction of BSI in these patients. However, when present, SBPs raise the risk of end-organ disease and, together with an MDR phenotype, can independently and significantly concur at increasing the risk of death. IMPORTANCE Bacterial bloodstream infection (BSI) is a significant complication in hematologic patients and is associated with high mortality rates. Despite improvements in BSI management, factors leading to sepsis are understood only partially. This study analyzes the contribution of bacterial biofilm on BSI development and mortality in patients with hematological malignancies (HMs). In this work, weak biofilm producers (WBPs) were significantly more abundant than strong biofilm producers (SBPs). However, when present, SBP bacteria raised the risk of end-organ disease in HM patients developing a BSI. Besides, SBPs, together with a multidrug-resistant (MDR) phenotype, independently and significantly concur at increasing the risk of death in HM patients. The characterization of microbial biofilms may provide key information for the diagnosis and therapeutic management of BSI and may help develop novel strategies to either eradicate or control harmful microbial biofilms.

Molecular Imaging of Cardiovascular Device Infection: Targeting the Bacteria or the Host-Pathogen Immune Response?

Rapid and accurate diagnosis of cardiovascular device infection remains a challenge in the clinic. Anatomic imaging tools such as echocardiography and cardiac CT or CT angiography are the first-line modalities for clinically suspected endocarditis given their ability to detect vegetation and perivalvular complications. Accumulating data suggest that functional imaging with 18F-FDG PET/CT has unique merits over anatomic imaging and could potentially diagnose early cardiac device infection before morphologic damage ensues and identify infection sources or bacterial emboli in the rest of the body. Although an abnormal finding on 18F-FDG PET/CT was added to the 2015 guidelines of the European Society of Cardiology as a major criterion for the diagnosis of device-related and prosthetic valve endocarditis, that addition has not been incorporated in the U.S. guidelines. Beyond these clinically available imaging tools, attempts have been made to develop bacteria-targeting tracers for specific infection imaging, which include tracers of bacterial maltodextrin transporter, bacterial thymidine kinase, antibiotics, antimicrobial peptides, bacterial antibodies, bacteriophages, and bacterial DNA/RNA hybrid nucleotide oligomers. Most of the tracers have been studied only in experimental animals, except for radiolabeled antibiotics, which have been examined in humans without success in clinical translation for infection imaging. In this article, we compare the roles of anatomic and functional imaging for cardiac device infection and discuss the pros and cons of 18F-FDG and bacteria-targeting tracers. While anticipating continued investigations for bacteria-specific tracers in the future, we recommend that 18F-FDG PET/CT, which represents the host-pathogen immune response to infection, be used clinically for identifying cardiovascular device infection.

The obligatory role of host microbiota in bioactivation of dietary nitrate.

Nitric oxide (NO) is a key signalling molecule in the regulation of cardiometabolic function and impaired bioactivity is considered to play an important role in the onset and progression of cardiovascular and metabolic disease. Research has revealed an alternative NO-generating pathway, independent of NO synthase (NOS), in which the inorganic anions nitrate (NO3-) and nitrite (NO2-) are serially reduced to form NO. This work specifically aimed at investigating the role of commensal bacteria in bioactivation of dietary nitrate and its protective effects in a model of cardiovascular and metabolic disease. In a two-hit model, germ-free and conventional male mice were fed a western diet and the NOS inhibitor l-NAME in combination with sodium nitrate (NaNO3) or placebo (NaCl) in the drinking water. Cardiometabolic parameters including blood pressure, glucose tolerance and body composition were measured after six weeks treatment. Mice in both placebo groups showed increased body weight and fat mass, reduced lean mass, impaired glucose tolerance and elevated blood pressure. In conventional mice, nitrate treatment partly prevented the cardiometabolic disturbances induced by a western diet and l-NAME. In contrast, in germ-free mice nitrate had no such beneficial effects. In separate cardiovascular experiments, using conventional and germ-free animals, we assessed NO-like signalling downstream of nitrate by administration of sodium nitrite (NaNO2) via gavage. In this acute experimental setting, nitrite lowered blood pressure to a similar degree in both groups. Likewise, isolated vessels from germ-free mice robustly dilated in response to the NO donor sodium nitroprusside. In conclusion, our findings demonstrate the obligatory role of host-microbiota in bioactivation of dietary nitrate, thus contributing to its favourable cardiometabolic effects.

Contamination profile in allografts retrieved from multitissue donors: longitudinal analysis.

Microbiological contamination of retrieved tissues has become an issue of key importance and is a critical aspect of allograft safety, especially in the case of multi-tissue donations, which frequently become contaminated during retrieval and handling. We analysed contamination in 11,129 tissues with a longitudinal contamination profile for each individual tissue. Specifically, 10,035 musculoskeletal tissues and 1094 cardiovascular tissues were retrieved from a total of 763 multi-tissue donors, of whom 105 heart-beating organ donors and 658 deceased tissue donors. Of the 1955 tissues found to be contaminated after the first decontamination step, 1401 tissues (72%) were contaminated by the same species as the one(s) isolated at retrieval (Time1) and 554 (28%) by different species. Among the 113 tissues testing positive after the 2nd decontamination (Time3), 36 tissues (32%) were contaminated by the same species detected at Timel while the contaminating species differed from Time1 in 77 tissues (68%). The higher the number of contaminating species per tissue the higher the percentage of tissues in which contamination changed over time compared to Time1. The analysis revealed a 28% incidence of new species in tissues already testing positive after retrieval and of 3.5% of tissues becoming positive after admission to the tissue bank. Of these, coagulase-negative Staphylococcus accounted for over 70% of new contaminations.

The gut microbiota as a novel regulator of cardiovascular function and disease.

The gut microbiome has emerged as a critical regulator of human physiology. Deleterious changes to the composition or number of gut bacteria, commonly referred to as gut dysbiosis, has been linked to the development and progression of numerous diet-related diseases, including cardiovascular disease (CVD). Most CVD risk factors, including aging, obesity, certain dietary patterns, and a sedentary lifestyle, have been shown to induce gut dysbiosis. Dysbiosis is associated with intestinal inflammation and reduced integrity of the gut barrier, which in turn increases circulating levels of bacterial structural components and microbial metabolites that may facilitate the development of CVD. The aim of the current review is to summarize the available data regarding the role of the gut microbiome in regulating CVD function and disease processes. Particular emphasis is placed on nutrition-related alterations in the microbiome, as well as the underlying cellular mechanisms by which the microbiome may alter CVD risk.

Bacteriology testing of cardiovascular tissues: comparison of transport solution versus tissue testing.

Bacteriology testing is mandatory for quality control of recovered cardiovascular allografts (CVA). In this paper, two different bacteriology examinations (A tests) performed before tissue antibiotic decontamination were compared: transport solution filtration analysis (A1) and tissue fragment direct incubation (A2). For this purpose, 521 CVA (326 heart and 195 artery tissues) from 280 donors were collected and analyzed by the European Homograft Bank (EHB). Transport solution (A1) tested positive in 43.25 % of hearts and in 48.21 % of arteries, whereas the tissue samples (A2) tested positive in 38.34 % of hearts and 33.85 % of arteries. The main species identified in both A1 and A2 were Staphylococcus spp. in 55 and 26 % of cases, and Propionibacterium spp. in 8 and 19 %, respectively. Mismatches in bacteriology results between both initial tests A1 and A2 were found. 18.40 % of the heart valves were identified as positive by A1 whilst 13.50 % were considered positive by A2. For arteries, 20.51 % of cases were positive in A1 and negative in A2, and just 6.15 % of artery allografts presented contamination in the A2 test but were considered negative for the A1 test. Comparison between each A test with the B and C tests after antibiotic treatment of the allograft was also performed. A total decontamination rate of 70.8 % of initial positive A tests was obtained. Due to the described mismatches and different bacteria identification percentage, utilization of both A tests should be implemented in tissue banks in order to avoid false negatives.

Dynamics of spread of Salmonella enterica in the systemic compartment.

Traditional microbiological and immunological tools, combined with modern imaging, and molecular and mathematical approaches, have revealed the dispersive nature of Salmonella infections. Bacterial escape from infected cells, spread in the tissues and attempts to restrain this process by the host give rise to fascinating scenarios that underpin the pathogenesis of salmonelloses.

Bacterial invasion of vascular cell types: vascular infectology and atherogenesis.

To portray the chronic inflammation in atherosclerosis, leukocytic cell types involved in the immune response to invading pathogens are often the focus. However, atherogenesis is a complex pathological deterioration of the arterial walls, where vascular cell types are participants with regards to deterioration and disease. Since other recent reviews have detailed the role of both the innate and adaptive immune response in atherosclerosis, herein we will summarize the latest developments regarding the association of bacteria with vascular cell types: infections as a risk factor for atherosclerosis; bacterial invasion of vascular cell types; the atherogenic sequelae of bacterial presence such as endothelial activation and blood clotting; and the identification of the species that are able to colonize this niche. The evidence of a polybacterial infectious component of the atheromatous lesions opens the doors for exploration of the new field of vascular infectology and for the study of atherosclerosis microbiome.

Roles of oral bacteria in cardiovascular diseases--from molecular mechanisms to clinical cases: Cell-surface structures of novel serotype k Streptococcus mutans strains and their correlation to virulence.

Streptococcus mutans is generally known as a pathogen of dental caries, and it is also considered to cause bacteremia and infective endocarditis (IE). S. mutans was previously classified into 3 serotypes, c, e, and f, due to the different chemical compositions of the serotype-specific polysaccharides, which are composed of a rhamnose backbone and glucose side chains. We recently designated non-c/e/f serotype S. mutans strains as novel serotype k, which is characterized by a drastic reduction in the amount of the glucose side chain. A common biological feature of novel serotype-k strains is a lower level of cariogenicity due to alterations of several major cell surface protein antigens. As for virulence in blood, these strains survive in blood for a longer duration due to lower antigenicity, while the detection rate of all strains carrying the gene encoding collagen-binding adhesin has been shown to be high. Furthermore, molecular biological analyses of infected heart valve specimens obtained from IE patients revealed a high detection rate of serotype-k S. mutans. Together, these findings suggest that serotype-k S. mutans strains show low cariogenicity but high virulence in blood as compared to the other serotypes, due to alterations of several cell surface structures.

System analysis of changes in cardiovascular circulatory dynamics in experimental diphtheria in rabbit.

Trivariate correlation analysis of hemodynamic indices of the cardiovascular system in rabbits with diphtheria showed that adaptation of this system to direct action of diphtherin can be visualized by analysis of trivariate correlation tightness for indices of intraventricular pressure in the left and right ventricles and indices of systemic blood pressure. Using empirical production functions for systemic blood pressure indices we found that the contribution of intraventricular pressure in the left and right ventricles on blood pressure values is changed in diphtheria compared to the control. Basing on entropy analysis we established that the regimen of control over values of working intraventricular pressure in both left and right ventricles in diphtheria is changed from quasidetermined to stochastic.

Porphyromonas gingivalis and the autophagic pathway: an innate immune interaction?

Autophagy is a mechanism used to maintain several intracellular functions essential to eukaryotic cells. Recently, a role for autophagy in innate and adaptive immunity has also been established including the elimination of invading bacteria. Although some intracellular pathogens are killed by autophagy, several others subvert autophagy to the pathogen's benefit for survival and replication. Porphyromonas gingivalis, an important periodontal pathogen, has been shown to stimulate autophagy in endothelial cells and to use the autophagic pathway to its advantage. In human coronary artery endothelial cells (HCAEC), P. gingivalis localizes within autophagosomes. After intracellular uptake, P. gingivalis transits from early autophagosomes to late autophagosomes and prevents the formation of autolysosomes, either by delaying the autophagosome-lysosome fusion or by redirecting the normal autophagic trafficking. In addition, P. gingivalis was also found to stimulate autophagy in human aortic endothelial cells (HAEC) since co-localization of LC3-II, an autophagosome marker, with P. gingivalis was observed. The trafficking of P. gingivalis into the autophagic pathway appears to be dependent upon the host cell type. Survival of P. gingivalis through the subversion of the host autophagic pathway can be considered a bacterial strategy to evade the innate immune system and persist in the host.

Biotypes of Candida albicans isolated from cardiovascular system and skin surveillance cultures of hospitalized patients.

The aim of the study was to biotype 59 isolates of Candida (C.) albicans from cardiovascular system samples (blood and intravenous catheter) and 123 isolates of the same species from skin surveillance cultures (swabs of the armpit, groins and intravenous catheter insertion sites) of hospitalized patients using the Odds and Abbott biotyping method. Biotyping of 59 isolates of C. albicans taken from the cardiovascular system samples revealed the presence of 16 biotypes. Biotype 355 was the most common biotype, accounting for 35.6% of all biotype isolates from this system. Biotyping of 123 C. albicans isolates from skin surveillance cultures detected 21 biotypes. Biotype 355 was most common, accounting for 17.9% of all biotype isolates from these samples. The two systems had 10 biotypes in common: 355, 155, 257, 305, 105, 315, 300, 015, 157, and 345. These biotypes accounted for 88.3% and 81.4% of all C. albicans biotypes isolated from the cardiovascular system and skin surveillance cultures, respectively. Biotypes 355, 155, and 257 were the biotypes most frequently shared in isolates from the two systems. These biotypes accounted for 57.7% and 43.1% of all C. albicans biotypes isolated from the cardiovascular system and skin surveillance cultures, respectively.

Immunopathogenesis of atherosclerosis.

Recent clinical studies indicate that the number of microbial infections (the "pathogen burden") critically determines the development and progression of atherosclerotic disease. Viruses or bacteria with a specific tropism for cells of the vascular wall may contribute to the initial vascular injury via direct cytopathic effects or via the induction of genuine autoimmune responses. Immunopathological processes such as molecular mimicry, epitope spreading, or bystander activation of self-reactive lymphocytes most likely fuel the chronic inflammatory process in the vascular wall. Recognition of atherogenesis as a pathogen-driven, immunopathological process makes this disease amenable to new treatment strategies such as vaccination or immunomodulation.

A porcine model of peritonitis and bacteremia simulates human septic shock.

Cardiovascular responses to systemic bacteremia were evaluated in a pre-instrumented, conscious pigs. Basal observations were obtained 5-7 days after instrumentation. On the next day, Escherichia coli 0111.B4 (1.1 to 33 x 10(9) CFU/kg)-laden fibrin clots were implanted intraperitoneally. Nonsurvivors (9/18) demonstrated rapid cardiovascular decompensation. Survivors (9/18) demonstrated significant cardiovascular injury, which was reversed by 5-7 days postimplant. Cardiac inotropicity was significantly reduced in this period, but recovered by day 7. Circulating myocardial depressant substance activity (assayed by serum-induced depression of beating neonatal rat myocytes) was present on days 1-4 of bacteremia and recovered to basal values on day 6. No clinical or cardiovascular changes were seen in pigs implanted with sterile clots (n = 4). These data demonstrate that implantation of bacteria-laden fibrin clots in pigs induces cardiovascular alterations that mimic responses seen in human sepsis.