10 Mental Health and Multi-Microbiome Interactions
10 Mental Health and Multi-Microbiome Interactions
Mental Health and Multi-Microbiome Interactions
It may seem obvious that localized microbiomes are responsible for diseases related to their respective areas (e.g., IBD and the gut microbiome or AD and the skin microbiome), however, it is a fascinating phenomenon that various microbiomes can affect each other and influence health in different parts of the body. Even more captivating is the link between certain microbiomes and mental health conditions presuming the brain is devoid of microbes.
These links between microbiomes are referred to as axes, and initial connections began with the most well-studied microbiome, the gut. Since many gut-derived microbial-produced molecules and compounds are spread through the bloodstream, associations with various organs are formed, such as the gut-brain axis, gut-skin axis, gut-lung axis, or a combination of multiple; gut-brain-skin axis. There are likely overlapping connections between all microbial components that form the human holobiome, thus teasing apart the exact members and their functions is a dutiful task.
Gut Interaction with Other Microbiomes
As mentioned earlier, the dissemination of molecules and compounds from the gut to the rest of the body creates an interconnected highway affecting most, if not all, parts of the body. Certainly, juxtaposed regions such as the oral cavity and the proximal portions of the GI tract have a relationship between their microbiomes, which it termed the gut-oral axis (GOA). These linked microbiomes have been shown to have immunomodulatory roles in the development of rheumatoid arthritis (RA) and osteoarthritis (OA) under dysbiosis, where the abundance of oral Porphyromonas gingivalis and intestinal Prevotella copri could be responsible (Drago et al., 2019, du Teil Espina et al., 2019). It has also been proposed that dysbiosis of the gut-oral microbiome axis is implicated in cirrhosis of the liver through pathogen invasion, resultant systemic inflammation, and impaired immunity and liver function (Acharya et al., 2017). Even gastrointestinal conditions like IBD and cancer of the colon, liver, and pancreas are linked with both the gut and oral microbiome dysbiosis, further demonstrating this strong interorgan connection to human health (Park et al., 2021).
The gut and the skin microbiomes are also linked via the gut-skin axis (GSA), and as the primary interface to the environment, they have major roles in physiological health (Figure 1). Dysbiosis of the gut-skin microbiome axis has influence on both GI and cutaneous disorders such as IBD, celiac disease, atopic dermatitis, psoriasis, acne, and other dermatologic issues, where each of these diseases can be associated with the ‘partner disease’ (i.e. a disease in one system linked to a disease in another system) (O’Neill et al., 2016, Salem et al., 2018, De Pessemier et al., 2021). Though crosstalk is bidirectional, more research seems to have focused on skin disorders