A concept originating from 1999 is that our gut is our second brain, with gut bacteria as an integral part. Indeed, our gut microbiota is producing many signaling molecules (e.g. serotonin), influencing distant parts of our body, including our actual brain, or the skin.
Many of the known species of bacteria and fungi that we encounter are pathogenic, or at least opportunistic; they could be part of a normal microbiota, but under the right circumstances, they will switch from commensal to predatory. However, contemporaries of Pasteur, notably Élie Metchnikoff (1845-1916), put forth the idea that many of our commensal micro-organisms are more than neutral, but beneficial. And the more we have been looking at the microbiota, the more this proved to be true. Commensal bacteria are an important part of our defense against pathogenic microbes, and the benefices do not stop there.
Babies get the seeds of their microbiota, oral, skin and guts, from their mother as they go through the birth canal, and later collect other germs from their caregivers, and their environment at large. A fascinating field of study is the impact of birth by c-section: babies delivered this way start with a different microbiota. Eventually, they acquire skin and gut microbiota similar to babies born vaginally, but the time spent with an immature microbiota has bad consequences: c-section babies have a higher risk of autoimmune diseases, allergies, and infections. Ensuring that newborn babies quickly achieve properly diverse microbiota is a current research topic.
On the other end of the human experience, in the elderly, microbiota has been linked to aging markers, from skin wrinkles to the onsets of some illness, including dementia and Alzheimer’s disease. It remains to be determined which type of microbiota would be protecting and which one would be harmful.
Recent research is suggesting that our skin microbiota is exchanging signals with distant organs and microbiota, notably the guts-brain axis. If anything, skin microbiota is deeply involved in skin health and aging. These studies showing the extend of the signaling between microbiota and host, inside one microbiota, and maybe between microbiota, are pointing to a key parameter of a healthy microbiota: the metabolic functions a microbial community is providing are likely as important, if not more, than its composition.
Phylogene has been proposing targeted techniques like qPCR to search and monitor specific species of bacteria or fungi, allowing to show the specific impact – or lack of an impact – of a condition on microbial population.
For a larger-scale view, Phylogene can produce metagenomics analyses: the overall sequencing of species-specific regions (16S rRNA or fungal ITS), to describe the species composition of a microbiota population and show the impact of the tested condition on microbial diversity.
Finally, Phylogene developed metaproteomics analyses: the identification and relative quantification between two or more conditions of the present proteins from both the microbes and the host. This approach will focus on the functional aspect of microbiota in addition to its composition, shows which pathways are being more involved in a tested condition, and more generally the impact of a tested condition on both the microbiota and the host, e.g. the host skin health if studying the skin microbiota, while still providing data about the microbiota taxa composition and diversity. To complement metaproteomics analyses, we are proposing a bioinformatics analysis, HolXplore TM, in which the data is submitted to a taxonomic analysis and a functional analysis, helping data interpretation in the context of the tested conditions and the generation of claims.
References
Cao F, Ogonowski NS, et al. Unravelling the causal link between gut microbiota and acne risk using a genetic approach. Skin Health Dis. 2025 – doi: 10.1093/skinhd/vzaf077
Hawkins B, Montgomery M, et al. Gut microbiota dysbiosis at the interface of neuropsychiatric disorders and their dermatological comorbidities. Gut Microbes. 2025 – doi: 10.1080/19490976.2025.2574934
Wang Y, Xing J, et al. The complex interplay between psoriasis and depression: from molecular mechanisms to holistic treatment approaches. Front Immunol. 2025 – doi: 10.3389/fimmu.2025.1659346
Challa V, Prajapati SK,et al. Microbiome-Aging-Wrinkles Axis of Skin: Molecular Insights and Microbial Interventions. Int J Mol Sci. 2025 – doi: 10.3390/ijms262010022
CONTACT
Mrs Camille Drubigny
c.drubigny@albhades.com
