Metabolic syndrome is a group of human conditions including abdominal obesity, hypertension, dyslipidemia and hyperglycemia, all of which are risk factors for type 2 diabetes, cardiovascular disease and steatotic liver disease associated with metabolic dysfunction.
All these diseases constitute a global public health problem, with a very significant increase in frequency associated with the adoption of the modern Western lifestyle. Diet is a well-known risk factor for MetS, but other changes associated with the modern Western lifestyle could also contribute to the metabolic syndrome. We hypothesized that the disappearance of commensal amoebae, which have always resided in our intestines, could contribute to the emergence of MetS in association with dietary changes.
To test this hypothesis in animals, mice were fed a high-fat diet or a normal diet and colonized or not withEntamoebamuris, a commensal amoeba. 70 days after inoculation, cecal microbiota and bile acid composition were analyzed by high-throughput 16S rDNA sequencing and mass spectrometry respectively. Cytokine concentrations were measured in intestine, liver and mesenteric fat in search of low-grade inflammation. The impact of the high-fat diet on liver metabolic dysfunction was explored by Oil Red O staining, triglyceride and cholesterol concentrations and expression of genes involved in beta-oxidation and lipogenesis.
Colonization withE. murisahad a beneficial impact, with reduced dysbiosis, lower levels of fecal secondary bile acids and improved hepatic steatosis, arguing for a protective role of commensal amoebae in the metabolic syndrome and more specifically in liver disease associated with the high-fat diet.
This work complements a recent publication in the journal “Cell” showing that the presence of another protozoan(Blastocystishominis) in the gut was associated with a lower incidence of metabolic syndrome in humans(https://linkinghub.elsevier.com/retrieve/pii/S0092867424006925).
It therefore seems that the eukaryotic microbiota may play a protective role in metabolic adaptation to the modern Western diet.
The article is available here: https://www.tandfonline.com/doi/full/10.1080/19490976.2024.2409210#d1e685
Inserm press release: https: //www.inserm.fr/actualite/maladie-du-foie-gras-un-effet-protecteur-des-amibes-intestinales/