Characterization of the gut microbiota and metabolome in healthy and unhealthy obese patients

Metabolically healthy (MHO) and unhealthy (OB) obese patients showed different risk of related comorbidities, e.g., diabetes, cardio-metabolic diseases, and cancer. The gut microbiota plays a pivotal role in the regulation of host metabolism and several studies reported the link between obesity and dysbiosis. Here, based on clinical data and dietary life-style habits, the characterization of gut microbiota and faecal volatile metabolome were investigated in both MHO and OB cohorts. We here carried out an observational study where obese patients stratified into two groups were compared with healthy control subjects (HC). Blood samples and food questionnaires were collected. Faecal samples were used for characterization of i) gut microbiota, through quantitative PCR; and ii) gut metabolome with gas chromatography coupled with mass spectrometry. A dedicated statistical approach, i.e., rotating factor and discriminant analysis of principal components, was used to focus the attention on a subpanel of variable that clinically support the pathologic obese status. Biochemical profile of HC and MHO subjects showed statistically significant differences compared to OB patients. Taxa content in terms of presence/ absence and abundances was inspected and, as a result, the abundance of Clostridium coccoides was higher in HC subjects than both obese groups. Lactobacillus genus and Lactiplantibacillus plantarum were detected to be higher in MHO subjects compared to HC, whereas a greater amount of Prevotella, Desulfovibrio, and Lactiplantibacillus plantarum characterized OB subjects. Pattern of metabolites, including acetone, beta-myrcene, alphaterpineol, and other volatile compounds, differentiated the three groups. In addition, Butanoic acid was lower in OB subjects, compared to MHO. The gut microbiota differences between healthy and obese subjects contribute to the understanding of the association between the gut microbiota and these metabolic diseases and, if confirmed by further large-scale studies, could represent potential biomarkers for a less invasive diagnosis of morbid obesity.