Abstract
Angiolipomas are benign subcutaneous nodules composed of mature adipose tissue with thin-walled, dilated and tortuous small blood vessels, displaying intraluminal deposition of fibrin microthrombi formed from fibrinogen. The latter, considered not only as a diagnostic hallmark of angiolipoma, but also as a marker of vascular permeability. It is known that human adipose tissue (AT) growth, expansion, and maintenance is angiogenesis dependent and involves adipocytes, immune cells , fibroblasts, adipose stem cells and preadipocytes, all of them supported by an extracellular matrix. Interestingly, emerging evidence have emphasized that adipocytes maintain a bidirectional communication (crosstalk) with adipose endothelial cells (ECs) in healthy and pathological tissues and that this reciprocal and dynamic communication is crucial not only for the growth, expansion and maintenance of the AT, but also for the formation of new capillaries (angiogenesis) or microvasculature remodeling. However, the signals and mediators involved in this communication remain to be investigated.
Herein, we show that in angiolipoma GAL-1, -3 and -8 and some of their binding partners that includes proteoglycans such as perlecan, agrin, CD44 and endocan, as well as glycoproteins including TLR4, fibronectin, thrombospondin-1, integrin β1, PECAM-1, endoglin, VE-cadherin, and neuropilin-1, were immunolocalized around mature adipocytes that were in close proximity to small blood vessels, as well as in the ECs lining the lumen of these vessels.
We propose that in angiolipoma, GAL-1, -3 and -8 acting in concert with their binding partners form a supramolecular multivalent structure on the surface of mature adipocytes and ECs that might be facilitating the bidirectional communication (crosstalk) between adipocytes and ECs, contributing to the mature adipocytic expansion and the new vasculature formation (angiogenesis) or microvasculature remodeling.