Macrophages in human obesity – the effect of laparoscopic gastric bypass surgery on subcutaneous adipose tissue inflammation

Excess weight and obesity relate to multiple comorbidities, lost quality of life and mortality and cause major burden to healthcare and society. Most obesity seems to trace to changes in lifestyle and the food environment in the last few decades. The comorbidities related to obesity are increasingly viewed as a result of low-grade inflammation characterizing the state of excess adiposity. On microscopic level, this associates with the infiltration of immune cells, particularly macrophages, into adipose tissue. Bariatric surgery and weight loss repeal these alterations.
In this thesis, two behaviorally distinct macrophage pools are identified in subcutaneous adipose tissue of subjects with obesity. Of these, only the macrophages associated with pyroptotic adipocyte deaths decreased after laparoscopic Roux-en-Y gastric bypass for obesity. These macrophages were also highly imbued by known pro-inflammatory proteins, NLRP3 inflammasome and Caspase-1 which are associated with type 2 diabetes and insulin resistance in adipose tissue. The surgery associated with a shift of adipocyte size towards smaller populations.
In addition, a novel method was developed for fat cell size and count analysis using free open-source software.