Macrophage Differentiation and Cholesterol Efflux

THP-1 human monocytes (RIKEN, Tsukuba, Japan) were cultured in an RPMI-1640 medium containing 10% fetal bovine serum (Life Technologies Co, Carlsbad, CA, USA), 100 units/mL of penicillin G, and 100 μg/mL of streptomycin. THP-1 cells were treated with 10 μg/mL of PMA and 3.4% β-mercaptoethanol for 72 h prior to differentiation to macrophages [31 (link)]. After differentiation, the RPMI-1640 was used with with 4.5 g/L of high glucose for cholesterol efflux. For all experiments, cells were maintained in a serum-free medium containing 0.2% BSA supplemented with or without additives (5 μmol/L of T0901317 and 9-cis-retinoic acid or GLP-1). Sitagliptin phosphate, exendin-(9–39), and a PKA inhibitor were added 30 min prior to incubation with GLP-1. The concentrations of the DPP-4 inhibitor and GLP-1 in this study were selected in accordance with previous reports [24 (link),30 (link),32 (link),33 (link)].