Preadipocyte Conversion to Macrophage

Abstract

Preadipocytes are present throughout adult life in adipose tissues and can proliferate and differentiate into mature adipocytes according to the energy balance. An increasing number of reports demonstrate that cells from adipose lineages (preadipocytes and adipocytes) and macrophages share numerous functional or antigenic properties. No large scale comparison reflecting the phenotype complexity has been performed between these different cell types until now. We used profiling analysis to define the common features shared by preadipocyte, adipocyte, and macrophage populations. Our analysis showed that the preadipocyte profile is surprisingly closer to the macrophage than to the adipocyte profile. From these data, we hypothesized that in a macrophage environment preadipocytes could effectively be converted into macrophages. We injected labeled stroma-vascular cells isolated from mouse white adipose tissue or 3T3-L1 preadipocyte cell line into the peritoneal cavity of nude mice and investigated changes in their phenotype. Preadipocytes rapidly and massively acquired high phagocytic activity and index. 60 -70% of preadipocytes also expressed five macrophagespecific antigens: F4/80, Mac-1, CD80, CD86, and CD45. These values were similar to those observed for peritoneal macrophages. In vitro experiments showed that cell-to-cell contact between preadipocytes and peritoneal macrophages partially induced this preadipocyte phenotype conversion. Overall, these results suggest that preadipocyte and macrophage phenotypes are very similar and that preadipocytes have the potential to be very efficiently and rapidly converted into macrophages. This work emphasizes the great cellular plasticity of adipose precursors and reinforces the link between adipose tissue and innate immunity processes.

Macrophage-conditioned medium inhibits the differentiation of 3T3-L1 and human abdominal preadipocytes

“…Of course, the nature of paracrine interactions between macrophages and adipose cells in vivo are likely to be more complex. Infiltrating macrophages could represent a special subpopulation of circulating monocytes, and it has even been suggested that adipose tissue macrophages may arise from adipose stromal cells [38]. Furthermore, the profile of cytokines secreted by resident macrophages may be influenced by adipose cells.…”

Developing dendritic cells become ‘lacy’ cells packed with fat and glycogen

“…29 Pre-adipocytes are reported to have properties of macrophages, 33,34 and cells from adipose tissue can transdifferentiate into macrophages in vivo. 35 Indeed, cells within fat have some general properties of pluripotential stem cells or of haematopoietic stem cells. [36][37][38][39] Myeloid cells from adipose tissue also contribute to immune responses.…”

Heat shock protein 60: Evidence for receptor‐mediated induction of proinflammatory mediators during adipocyte differentiation

“…Adipocytes are a population of mesenchymal-derived cells with a close phylogenetic relationship to innate immune cells [1]. They develop from precursor cells, the preadipocytes, which represent a prevalent population of the stromal vascular cell fraction.…”