PAF signaling plays a role in obesity-induced adipose tissue remodeling

Platelet-activating factor receptor (PAFR) activation controls adipose tissue (AT) expansion in animal models. Our objective was twofold: (i) to check whether PAFR signaling is involved in human obesity and (ii) investigate the PAF pathway role in hematopoietic or non-hematopoietic cells to control adipocyte size.

Clinical parameters and adipose tissue gene expression were evaluated in subjects with obesity. Bone marrow (BM) transplantation from wild-type (WT) or PAFR^-/- mice was performed to obtain chimeric PAFR-deficient mice predominantly in hematopoietic or non-hematopoietic-derived cells. A high carbohydrate diet (HC) was used to induce AT remodeling and evaluate in which cell compartment PAFR signaling modulates it. Also, 3T3-L1 cells were treated with PAF to evaluate fat accumulation and the expression of genes related to it.

PAFR expression in omental AT from humans with obesity was negatively correlated to different corpulence parameters and more expressed in the stromal vascular fraction than adipocytes. Total PAFR^-/- increased adiposity compared with WT independent of diet-induced obesity. Differently, WT mice receiving PAFR^-/--BM exhibited similar adiposity gain as WT chimeras. PAFR^-/- mice receiving WT-BM showed comparable augmentation in adiposity as total PAFR^-/- mice, demonstrating that PAFR signaling modulates adipose tissue expansion through non-hematopoietic cells. Indeed, the PAF treatment in 3T3-L1 adipocytes reduced fat accumulation and expression of adipogenic genes.

Therefore, decreased PAFR signaling may favor an AT accumulation in humans and animal models. Importantly, PAFR signaling, mainly in non-hematopoietic cells, especially in adipocytes, appears to play a significant role in regulating diet-induced AT expansion.