Differences in the characteristic of gut microbiota and metabolome in adult subjects with healthy and unhealthy obesity

Introduction: Obesity, an urgent and growing global public health threat, is a significant risk for cardio-metabolic diseases. Studies suggest that metabolically healthy obese subjects are at lower risk of cardio-metabolic diseases than metabolically unhealthy obese ones. To date, the role of microbiota in the development of these two different obesity phenotypes is still unknown. The aim of this study was to characterize gut microbiota and metabolome composition and functionality in metabolically healthy and unhealthy obese adult subjects considering their clinical data and dietary conditions. Materials and Methods: An observational study was conducted on healthy controls and metabolically healthy and unhealthy obese subjects. Blood samples and food questionnaires were collected. The gut microbiota was characterized in faecal samples through quantitative PCR. Gas chromatography coupled with mass spectrometry was performed for the analysis of untargeted metabolites and short-chain fatty acids. Result: The amount of Clostridium coccoides was lower in metabolically unhealthy obese than in healthy controls (q-value = 0.0003). Lactobacillus genus (q-value = 0.015) and Lactiplantibacillus plantarum (q-value = 0.015) species were higher in metabolically healthy obese subjects, while Prevotella (q-value = 0.03), Desulfovibrio (q-value = 0.02), and Lactiplantibacillus plantarum (q-value = 0.04) enriched the microbiome of metabolically unhealthy obese. The level of Acetone, beta-Myrcene, Tetradecane, 1,5,9-Undecatriene-2,6,10-trimethyl, 7-Hexadecanol, Estragole, alpha-Terpineol, Undec-6-en-2-one, 5,9-Undecadien-2-one-6,10-dimethyl, 2-Piperidinone, Nonanoic acid, 2,4-Ditertbutylphenol, and 6-Pentadecen-1-ol metabolites were significantly different among the three groups. In addition, a lower presence of Butanoic acid was observed in metabolically unhealthy obese. Conclusion: Lower proportions of Lactobacillus genus and Clostridium coccoides, higher proportions of Prevotella, Desulfovibrio, and Lactiplantibacillus plantarum, and metabolome diversity could be indicators of metabolic unhealthy obesity. These differences in microbiota and metabolome in adults with healthy and unhealthy obesity suggest that some characteristics of gut microbiota and metabolome could be involved in the link between morbid obesity and cardio-metabolic diseases.