The microbes inhabiting the human body generally exist within niche-specific microbiomes. Well-described microbiomes include those of gut, skin, oral cavity, oesophagus and lung. These niche-specific microbiomes appear to communicate via axes of activity that lead to changes in a spatially distant microbiome.
Communication between microbiomes has largely been defined by a cause and effect relationship, where a change within one niche-specific microbiome appears unlikely to have happened without a change at the other niche-specific microbiome site. 16S rRNA and whole genomic sequencing enables researchers to enumerate microbiota at phylum, class, genus and species level, and carry out comparative longitudinal and cross-sectional studies to identify changes in one microbiome compared to another. Perturbations in microbiota levels and the proteins expressed within a niche-specific microbiome can indicate the presence of a condition or disease state, and these effects may be transmitted via an axis of activity to another niche site. Examples include: increased short-chain fatty acid-expressing species in the gut microbiome enhancing persistence of Mycobacterium tuberculosis in the lung microbiome, and asthma in the lung linked to increased concentration of the histamine-secreting gut species Morganella morganii.
A more unusual cause-effect relationship involves Helicobacter pylori infection and Parkinson’s disease (PD). H. pylori gastric infection leads to worse outcomes for PD sufferers and eradication of H. pylori significantly improves motor function as well as the uptake of a drug used in the treatment of PD. This talk explores the axes of activity and potential pathways involved in this relationship.