Cohorte Obésité Bichat LOuis Mourier

The prevalence of obesity rapidly increased in the past decades in the French population with multiple health consequences (including hypertension, diabetes, sleep apnea syndrome, cardiovascular events, cancers…) responsible for excess mortality. In the same period of time, the number of bariatric procedures has developed exponentially. Indeed, there is presently little or no therapeutic alternatives in severe obesity, the pharmacotherapy of obesity having a poor efficacy. Despite its great efficacy on weight loss and resolution of comorbidities, bariatric surgery is not without risks. Indeed, it can be accompanied by side effects, including gastrointestinal disorders (transit disturbances, gastro-esophageal reflux, or dumping syndrome), surgical complications (gastric fistulas and bowel obstruction) and multiples nutritional deficiencies deleterious for health (anemia, neurological complication, bone loss, and protein malnutrition).

The mechanisms of development of obesity are still imperfectly known and, moreover, the observations made in murine models are not always transposable to humans. This is why it is necessary to establish human cohorts to specify better the pathophysiological mechanisms underlying the development of obesity and its complications and to identify new markers of response to medical and surgical treatments of obesity, in order to propose targeted therapies. In particular, the digestive tract, at the interface between the intake of nutrients and their metabolism, has a central role both in the development of obesity and in the effects of bariatric surgery.

Since 2000, bariatric surgery has been developed in University Hospital group of Paris Nord Val de Seine (HYPNVS) with a significant activity of about 600 procedures per year (mainly gastric bypass and sleeve gastrectomy). The well-systematized multidisciplinary clinical management makes it possible to phenotype the patients precisely. The collaboration between the obesity center and the INSERM 1149 research team promotes the implementation of transversal projects ranging from clinical research to basic research to deepen the physio-pathological mechanisms of obesity. Some perioperative biological samples (blood, DNA, adipose tissue, liver, intestine) were temporally collected in the surgical cohort of HUPNVS, leading to several research projects and international publications.

The team focuses on the mechanisms of gastrointestinal changes during obesity and bariatric surgery and previously showed profound changes in intestinal architecture, permeability, transport functions, metabolism, or in neuro-hormonal activity of the digestive tract. In these studies, it has been observed a plasticity of the epithelial cells constituting the gastrointestinal tract (including endocrine cells and enterocytes) that needs to be further documented. This plasticity that affects self-renewal, endocrine and digestive system and enteric nervous system, may allow epithelia to adapt to changes in the luminal environment (nutritional changes, modification of the microbiota, etc.) induced by obesity and bariatric surgery. Similarly, the connections of gastrointestinal tract with other tissues involved in metabolism and in particular the liver and adipose tissues affected by chronic inflammation and whose functions are impaired during obesity should be explored.

Our hypothesis is that a better understanding of the physio-pathological consequences of obesity and bariatric surgery, notably on the gastrointestinal tract, may allow to improve the treatment of obesity and to find alternatives to bariatric surgery.