Gut Microbiota and Cardiovascular Disease

Cardiovascular diseases are the leading cause of death worldwide.

One of the more important risk factors for atherosclerosis (hardening of the arteries) are lipid metabolism disorders, such as hypercholesterolemia (high cholesterol).

Bacteria

Improper metabolic processes play a contributory role in the development of certain cardiovascular diseases (CVDs) and are complex in nature. Atherosclerosis results from the interaction of a number of risk factors, such as the presence of lipid metabolism disorders like high cholesterol.

The first study to provide considerable evidence to link elevated lipid levels and coronary artery disease (CAD) was the renown Framingham Heart Study.

The International INTERHEART study revealed 9 independent risk factors for CAD:  dyslipidemia (abnormal lipids), arterial hypertension (high blood pressure), central (abdominal) obesity, diabetes, smoking, psychosocial factors, fruit and vegetable deficiency, alcohol abuse, and physical inactivity. Most of these are considered modifiable risk factors with dyslipidemia occurring most often.

However, even with large studies like these, there is insufficient data and CVD pathogenesis continues to need more thorough studies. Researchers have been focusing on finding new mechanisms that would enable more effective diagnostic and treatment methods.

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The role of microorganisms has been well documented among patients undergoing surgical procedures like pacemaker implantation and artificial heart valve replacement. Development of new technologies have resulted in improved knowledge of the human microbiome’s diversity.

The gut microbiome is referred to as a “virtual endocrine organ” due to the role it plays in the synthesis of short-chain fatty acids, amino acids, vitamins, and metabolites, and also affects processes that take place outside the digestive tract. This interaction between the host and digestive tract microbes is one determinant of host health.

Previous analyses have shown that changes in gut microbiota composition accounts for many metabolic disorders such as obesity, inflammatory bowel disease, rheumatoid arthritis, and type 2 diabetes.

It has also been proven that the gut microbiome of obese subject differs from that of healthy weight individuals.

The World Microbiome Project revealed how race, place of residence, and diet affect gut microbiota composition. Efforts have been made to assess if it is possible to modify microbiome composition so as to promote beneficial bacteria and develop prevention and therapeutic strategies.

Bacteria and virus seamless pattern inversion

Data was obtained from metagenomics analysis from twenty middle-aged male participants in Poland. Fifteen of these men had CAD and five had no cardiovascular problems. Twelve subjects lived in the city and eights lived in the countryside. All participants had central obesity and considered overweight or obese.

As in previous research, the gut microbiota of these men were considerably dominated by the phyla Firmicutes and Bacteroidetes.

Intestinal microbiota was found to be predominately Firmicutes (49%), Bacteriodetes (44%), Proteoacteria, and Actinobacteria orders. At the family level, Bacteroidaceae (25%), Ruminococcaceae (21%), Prevotellaceae (13%), Lachnospiraceae (13%), Veilonellaceae (11%), and Enterobacteriaceae (3%) dominated of the 45 microbial families. 67 genera were identified.

Analysis revealed changed within microbiota composition according to lipid parameters. Provotella was more abundant in patients with improper LDL cholesterol levels and/or improper total cholesterol levels vs. those with ideal levels, whereas Bacteroides was less abundant. Participants with ideal total cholesterol levels shows increased levels of Clostridium and Faecalibacterium compared to those with improper total cholesterol levels. Dialister was more pronounced in those with improper triglyceride levels. Higher Bacteroides = higher Parabacteroides. Higher Provotella = higher Desulfovibrio.

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The Polish study indicates that there is a higher abundance of Prevotella co-occurring with total cholesterol and LDL cholesterol disorders – the cholesterol fractions shown to be most responsible for CVD development.

Previous research has led to the conclusion that microbes can contribute to the development of atherosclerosis via food amines metabolism and the process of bile acids transformation.

Butyric acid is an important source of energy for intestinal epithelium (skin) cells and the intestinal effects f its activities include the improvement of inflammation, oxidative status, epithelial defense barrier regulation, and the modulation of visceral sensitivity and intestinal motility. Butyrate also down-regulates nine key genes involved in intestinal cholesterol biosynthesis, potentially inhibiting its pathway. Faecalibacterium, present in higher levels in those of healthy cholesterol levels, is one of the most abundant butyrate-producing bacterium in the gastrointestinal tract.

The way microbes affect our health does not result only from their quantity. It is also important to discover how they relate to one another and how the products of their metabolism affect us.

Rather than prescribing statin (cholesterol-lowering) drugs, perhaps we should instead consider the pro-atherogenic composition of gut microbiota as a possible cause – and therefore possible solution to – the problem.

SOURCE
Gozd-Barszczewska et al. “Gut microbiome as a biomarker of cardiometabolic disorders”. Ann Agric Environ Med. 2017;24(3):416-422. doi: 10.26444/aaem/75456
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