Bariatric surgery, adipose tissue and gut microbiota

Abstract

Human obesity can be viewed as a set of phenotypes that evolve over time in a sequence of stages that need to be precisely measured. Environmental, behavioral, genetic and biological factors interact to cause obesity. This presentation provides a clinical viewpoint on some biological processes that may explain some of the stages in the development of human obesity, its chronic maintenance and occurrence of complications, with a focus on brain structures, genetics, the profound alterations in adipose tissue biology and gut microbiota components. Roux-en-Y gastric bypass surgery is an increasingly effective model to study in this context because it leads to major improvements in glucose and lipid homeostasis and to the amelioration of some systemic inflammatory markers. International Journal of Obesity (2011) 35, S7-S15; doi:10.1038/ijo.2011.141Keywords: human obesity; adipose organ; inflammation; environment; gut microbiota Rapid progression of human obesity: multiple environmental factorsAlthough France is frequently considered as a country protected from obesity, the prevalence of obesity has nevertheless increased, as in many developed countries. Obesity in France is estimated to occur in 14.5% of the population aged over 15 years, and rose by 5-10% between the 1990s and 2000s (OBEPI study, 2009) Genetic factors barely explain the significant increase in the prevalence of obesity. Social and economic factors such as academic achievement, job title and income correlate with obesity epidemics. Eating habits are crucial, and numerous factors drive increased individual food intake, including availability and palatability of foods, visual and olfactory cues, conviviality, cultural attitudes, work-related eating habits and eating disorders. As in many countries, energy density of available foods and serving sizes influence the risk of obesity. 1 Although physical activity-related energy expenditure is increased in obese compared with lean subjects, the level of physical activity is classically lower in obese compared with lean subjects, and low physical activity levelFand increased sedentary behaviorFis associated with weight gain. On the other hand, increased body weight and obesity result in decreased physical activity, and therefore a complex and circular relationship occurs. 2 We are now in uncharted territory, our traditional model for eating is not relevant to modern lifestyles, and the profound changes in eating habits are not conducive to appropriate nutrition. As a result of changes in clothing, heating and means of transportation, we expend less energy than in past years; there is a decrease in the need for manual work and efforts to obtain food. Increased television-viewing time is usually associated with greater intake of energy-dense high-fat foods. Reduced sleep duration has been associated with obesity. 3 The discovery of a negative association between brown adipose tissue amount and outdoor temperature raises the question of a link between global warming and the worldwide progression of obesity. Alth...

The Human Gut Microbiome and Body Metabolism: Implications for Obesity and Diabetes

“…Recent findings raise the possibility that the gut microbiota has an important role in regulating weight and may be partly responsible for the development of obesity. Initial evidence of the relationship between obesity and gut microbial composition was reported 3 decades ago, when surgically induced weight loss through gastric bypass surgery and weight gain through lesions of the ventromedial hypothalamic nucleus were found to be associated with changes in gut microbial ecology ( 25, 26 ) . These earlier studies used culture-dependent methods, which detect a minority of microbes harbored in the gut.…”

Remodeling Intestinal Flora with Sleeve Gastrectomy in Diabetic Rats

“…More studies are about Roux-en-Y gastric bypass with obesity. However, the study of intestinal flora after sleeve gastrectomy in diabetes is still relatively rare [9, 10]. Compared with Roux-en-Y gastric bypass surgery, sleeve gastrectomy has less effects of intestinal structure, and it has not been reported whether it has a similar effect on the intestinal flora.…”

Gut microbiota after gastric bypass in human obesity: increased richness and associations of bacterial genera with adipose tissue genes

“…Along with the amelioration of systemic inflammation, a profound WAT remodeling is observed. It includes changes in histologic characteristics and gene expression (9,10) and modifications in transcriptional control of inflammation (11). RYGB also induces anatomic modifications of the gastrointestinal tract, which results in functional changes such as gut motility, pH, and alterations of bile acid flow and gut hormones secretions (12).…”