Supervisors info:
Εμμανουήλ Λέανδρος, Ομότιμος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ, Επιβλέπων
Κωνσταντίνος Γ. Τούτουζας, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Δημήτριος Θεοδώρου, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Summary:
The prevalence of obesity is exploding worldwide in our post-industrial era, with increasing morbidity and mortality.
The human gut microbiome exhibits a cardinal role in nutritional, physiological, metabolic, and immunological functions of the human body, and due to this multiplexity some authors consider it as an independent virtual organ by itself. Due to the big progress in phylogenetic investigation and quantification of gut microbiome through modern high-throughput sequencing, our understanding of the gut microbiome in health and diseases is rapidly advancing, and several studies have examined its role in obesity and its changes that occur following bariatric surgery.
There is growing evidence that obesity is associated to a specific profile of the gut microbiome which confers to the host an augmented ability for calories extraction, and reduced gut microbial diversity. However, the mechanism through which the gut microbiota and their by-products affect obesity remain mainly undiscovered and therefore more research is required to better comprehend the empirically observed connection between gut microbiome alterations and obesity.
On the other hand, bariatric surgery procedures, such as Roux-en-Y gastric bypass and vertical sleeve gastrectomy, are the most effective interventions for achieving pronounced and sustained weight loss and to normalize glycemic metabolism in obese patients. Bariatric surgery interventions are restoring a healthier microbiome, a leaner metabolic profile and this microbe rearrangement potentially contributes to the observed fat mass reduction, lean mass increase, and resolution of co-morbidities such as those observed following bariatric surgery. The exact mechanism is not certain, but it could be mediated by altering the enterohepatic bile acid circulation as well as altering the bile acid structure. Moreover, the bile acid activated farnesoid X transcription factor (FXR), is crucial for the beneficial effects of bariatric surgery on weight loss and glycose control improvement. However, recent data showed that the gut microbiota is not fully restored after bariatric surgery. Additionally, unidentified downstream targets such as the gut derived peptide FGF15/19, may potentially explain the positive metabolic effects of bariatric surgery.
More randomized controlled trials and larger prospective studies including well-defined cohorts are necessary to better identify the associations between the gut microbiome, obesity, and bariatric surgery.
Keywords:
Bariatric Surgery, Obesity, Gut Microbiota, Microbioma, Micronutrient Deficiency, Probiotics
