ABSTRACT
Defining what is “normal” in healthy microbiota communities is an ongoing process. Currently, there are key players that have already come to light with regard to many diseases. This chapter serves to identify which microorganisms and related mechanisms play a role in cardiovascular disease.
The gut microbiome regulates and influences many metabolic processes in the body. Research clearly indicates that the gut microbiome has a profound impact on the pathogenesis of cardiovascular disease. The gut microbiota is the collection of 40 trillion microorganisms living in the gastrointestinal tract, whereas the gut microbiome is the collection of total genes of these microorganisms. The cells of the human body are outnumbered by microbial cells 10 to 1 and the genes 150 to 1.1 These genes are so influential in many biological processes that there has been a major shift in the realm of research to examine these microorganisms as they relate to every function and dysfunction of the body. So far, there isn’t one chronic disease where an imbalance of this ecosystem hasn’t been observed.
The term “gut microbiome” was only coined in 2001, 2 but it wasn’t until 2007 that the science and understanding of the gut microbiome really progressed. Using technology developed for the Human Genome Project, scientists began to realize that the gut microbiome is essential to human health. This resulted in the National Institute of Health’s Human Microbiome Project, which set out to catalog the microorganisms living across the various human body’s “ecosystems.” The differences in diversity of the strains found in the human body are so vast, 3 and they dwarf the differences in biodiversity found between a tropical rainforest and a savanna when you combine all their respective flora and fauna.
A unique characteristic of the gut microbiome is that it appears to shift and adapt rapidly depending on what resources are present to meet the metabolic needs of the host. This means it is more important that we map the metabolic pathways (the means of obtaining a byproduct) and functions (the byproducts themselves) of these organisms, rather than focus on specific strains, because their behavior is dependent on their resources and the presence of other organisms.
It’s worth mentioning that some of the language used to describe microorganisms needs to change. Since strains once labeled “pathogenic” are proving to play vital roles in human health when they are in the appropriate numbers and location within the body, the more appropriate term is now considered “opportunistic.” Some bacteria are able to be either symbiotic or parasitic depending on the context, which is also called amphibiosis. An example of this is Helicobacter pylori, 4 which is generally associated with acute gastritis but has been found to also be protective against acid reflux. Another concern is the translocation of particular strains, which can sometimes cause issues. An example of this would be a condition called small intestinal bacterial overgrowth (SIBO), where colonic-type bacteria proliferate in large numbers in the small intestine.
