Review by Dr. Lindsay Rite
The role of the microbiome in human health and disease: an introduction for clinicians.
While gut health has been a long standing pillar at CHANGEpain, it appears to finally be getting some well deserved recognition in the mainstream research realm. Over the past month the British Medical Journal (BMJ) and the British Journal of Sports Medicine (BJSM) released a series on this topic. This week at Research Corner we will briefly review the BMJ article:
Young VB. The role of the microbiome in human health and disease: an introduction for clinicians. BMJ 2017; 356:j831. doi: 10.1136/bmj.j831
This was an exploratory literature review, references were obtained through PubMed and Medline searches of articles published between 1965 and 2016. As few high quality systematic reviews were available on this topic the author noted that recent RCT and high quality reviews were prioritized. Much of the high impact research available was observational and based on animal studies.
The role of clinical microbiology stemmed from Germ Theory and the complex consortia of bacteria in the natural environment. An evolution in our understanding in these arenas prompted an influx in large scale projects such as the National Institutes of Health (NIH) Human Microbiome Project and the MetaHIT consortium. It was highlighted that these and related projects have initiated a fostering towards better understanding of the microbial-human interrelationship.
An extensive summary on the concepts, structure, function, analysis techniques, host-microbe interactions, disease associations, antibiotics, prebiotics, probiotics and microbial restoration were discussed in this article. The focus on this literature review appeared to highlight the current understanding on the various microbiota-host interactions as well as present early stage clinical correlations in addition to proposed future research questions. While this was a lengthy article a few notable highlights include:
Various Microbe-Host Interactions have been studied:
These included the role of microbiota as a preventative strategy for colonization by disease and potentially pathogenic microbes as well as metabolic functions. A key mechanism in metabolic function is through the ability of microbiota to ferment resistant starch to produce a variety of compounds. This can have a variety of effects on the host including anti inflammatory and antitumor activity. Alterations in drug metabolism, bile salts and acids, lipid metabolism, epithelia response and systemic responses were also discussed.
Various microbiota disease associations have been noted:
Infectious Disease such as bacteremia, sepsis, and acute respiratory distress syndrome are now documented as having an association with host microbiome. Persons with inflammatory bowel disease (IBD) appear to have distinct differences compared to those without IBD. Further understanding of IBD appears to show a true “microbiome related disease” as the environment created through the interaction of host and microbe alter the condition. A pathogenic microbiota was also discussed as a proposed contributor to the development of the dysregulation that characterizes Crohn’s disease and ulcerative colitis.
Evidence was presented that showed a clear influence of the microbiota on the handling of nutrients by the intestinal track and close associations with the complex pathogenesis of obesity. Administration of antibiotics was said to disrupt the normal balance and skew individuals towards development of the metabolic syndrome and obesity.
Lastly, cultures suggest that the lungs host a low biomass of relatively diverse microbes. Acute upper respiratory tract infection with rhinovirus can alter the microbiota, and it has been suggested that this can lead to increased susceptibility to infections elsewhere in the respiratory tract, such as otitis media and pneumonia.
The author noted that the term microbiome refers not only to the microbes but also to the environment that they inhabit. Thus the gut microbiome refers not only to the microbes but also to elements of the host such as the host epithelium, immune components, and products of both the microbes and host including metabolites. The author also noted that although much of the work studying the indigenous microbiota has focused on bacteria, viruses and fungi also inhabit most body sites that are occupied by microbes. Various thoughtful future research questions were proposed following this review that may better enhance our current understanding.
As this was a literature review subjective measures were utilized to collect and interpret data.
Application at CHANGEpain:
Publication of this article in BJM highlights the growing interest of the microbiome in human health. While chronic pain was not directly discussed in this paper various chronic disease states such as infectious diseases, metabolic disease and irritable bowel syndrome were highlighted. As we know our chronic pain patients present with a host of comorbidities which of course include those noted. This is a chief reason why nutrition continues to be one of our five pillars of health at CHANGEpain. For further discussion, I recommend you contact Hanna Rakowska: she is our in house Holistic Nutritionist, and she is also an encyclopedia of related information!
This month's BJSM series: