The vascular network develops with remodeling in adipose tissue (AT) during obesity. We have found that PDGF-B detaches pericytes from the vasculature, which plays a crucial role in angiogenesis during obesity. The expression of PDGF-B was significantly elevated in obesity-associated infiltrated CD11c-positive (+) AT macrophages (ATMs). Interestingly, the expression was low in both CD11c+ ATMs and CD206+ ATMs of lean mice. Since glycolytic and oxidative metabolism are key metabolic programs that regulate ATMs’ polarity and function, we hypothesized that hyperglycemia and inflammation synergistically drive PDGF-B production by reprogramming metabolic pathways in ATMs.
The expression of PDGF-B was increased in the AT of high-fat diet (HFD)-fed mice and STZ-induced hyperglycemic mice. In accordance, exposure to high glucose led to increase the expression of PDGF-B in association with that of Itgax (CD11c) in RAW264.7 macrophages. In peritoneal macrophages, LPS but not IL-4 provoked PDGF-B expression, which was completely blocked by pretreatment with 2-DG, a glycolysis inhibitor. Moreover, LPS effectively augmented high glucose-induced its expression, and that was abolished by MG132, an NFκB inhibitor. Since macrophages highly accumulated in obese AT, where pericytes were detached from vasculature, we examined directly whether PDGF-B from macrophage involves in AT expansion during obesity. To this end, we intraperitoneally injected liposome-encapsulated clodronate (CL) to mice twice a week for 6 weeks during HFD feeding. ATMs were effectively depleted by CL with reduced PDGF-B expression in AT of HFD-induced obese mice. Importantly, HFD-induced obesity was effectively prevented by CL.
In conclusion, PDGF-B from ATMs has a crucial function in AT expansion during obesity. Hyperglycemia and chronic inflammation reprogram metabolic pathways toward glycolysis, and subsequent activation of NFκB plays a pivotal role in the production of PDGF-B in ATMs during obesity.
Y. Onogi: None. T. Wada: Research Support; Self; Sanwa Kagaku Kenkyusho Co., Ltd.. T. Matsuzawa: None. A. Okekawa: None. E. Watanabe: None. H. Tsuneki: None. T. Sasaoka: None.