Protozoa: only parasites or members of a healthy human gut ecosystem?

Summary

Microbial communities in the gut are essential for human health and development. For example, several modern-lifestyle related diseases are accompanied by changes in the gut microbiome and restoring a gut ecosystem could thus help in treating those diseases. However, we still know very little about what exactly a healthy microbiome looks like, and which factors shape its diversity and composition. In addition, most of the research so far has been conducted in industrialized societies that appeared relatively recently. Non-industrialized settings can provide us more insight into factors that have shaped gut microbiome variation throughout the human history and help us identify changes in living conditions that might play role in the rise of lifestyle-related diseases. Finally, most studies so far focused on bacteria and eukaryotes are rarely taken into account apart from parasitological contexts. I will present the analysis of the gut microbiomes of healthy individuals along a small-scale urbanization gradient in Cameroon, allowing to estimate the effect of lifestyle changes without confounding by geography or ethnic origin. Whereas we found only minor changes related to urbanization, the presence of commensal gut eukaryotes was the strongest determinant of gut microbiome variation, being more important than diet and a range of socioeconomic factors. In addition, I will show the first results of the analysis comprising hundreds of metagenomes from various, mostly non-industrialized populations all over the world aiming to assess how gut protozoa, geography and lifestyle shape the gut microbiome functional variation. To summarize, our results so far show that gut protozoa are commonly found in healthy people in traditional societies and their presence is positively correlated with microbiome diversity, indicating their potential role in the maintenance of a healthy gut ecosystem.

Recent publications:

1 Even G*, Lokmer A*, Rodrigues J, Audebert C, Viscogliosi E, Ségurel L, Chabé M. Changes in the Human Gut Microbiota Associated With Colonization by Blastocystis sp. and Entamoeba spp. in Non-Industrialized Populations. Front Cell Infect Microbiol. 2021 Mar 18;11:533528. doi: 10.3389/fcimb.2021.533528. PMID: 33816323; PMCID: PMC8013780. *Equal contribution.

2 Lokmer A, Aflalo S, Amougou N, Lafosse S, Froment A, Tabe FE, Poyet M, Groussin M, Said-Mohamed R, Ségurel L. Response of the human gut and saliva microbiome to urbanization in Cameroon. Sci Rep. 2020 Feb 18;10(1):2856. doi: 10.1038/s41598-020-59849-9. PMID: 32071424; PMCID: PMC7028744.

3 Lokmer A, Cian A, Froment A, Gantois N, Viscogliosi E, Chabé M, Ségurel L. Use of shotgun metagenomics for the identification of protozoa in the gut microbiota of healthy individuals from worldwide populations with various industrialization levels. PLoS One. 2019 Feb 6;14(2):e0211139. doi: 10.1371/journal.pone.0211139. PMID: 30726303; PMCID: PMC6364966.