Altered macrophage-like functions of preadipocytes in inflammation and genetic obesity

We recently demonstrated that preadipocytes exhibit functional features of macrophages, such as phagocytosis and anti-microbial activity, suggesting t hat preadipose cells could play a role in the inflammatory process or immun e response. The aim of this study was to compare these functions of both ma crophages and cells from stroma-vascular fraction (SVF) of the adipose tiss ue in two different situations, obesity and inflammation, characterized by alterations in immune responsiveness. We demonstrated that ob/ob mice exhib ited strong decrease in antimicrobial activity of both macrophages and SVF. This defect is compensated in SVF, at least in part, by an enhancement of phagocytosis that does not seem to be due to an increased macrophage number . In vitro leptin treatment of SVF and macrophages from obese mice did not restore their immune defects. Thioglycol late treatment of lean and obese m ice induced an inflammatory process that led to an increase in macrophage a ctivity in both strains. This stimulation also observed in SVF from lean mi ce is not present in obese ones. This work demonstrated that SVF immune fun ctions could be modified in different pathological situations such as infla mmation and obesity and sustained the new physiological role of preadipocyt es in these processes. (C) 2001 Wiley-Liss, Inc.