Fig. 5: Macrophage ox-LDL in HFD mice accumulated through the AT1R/ELAVL1/PPARγ/ABCA1 axis.

a–d Peritoneal macrophages derived from ND or HFD mice with or without ARB administration. a Peritoneal macrophages in the HFD mice showed upregulation of angiotensinogen and AT1R. b, c Levels of ox-LDL (b) and mRNAs of the inflammatory cytokines IL-1β, TNFα, and VEGF (c) were increased in macrophages from HFD mice. However, the levels were suppressed by systemic ARB administration. d The levels of ox-LDL in the plasma were not changed by HFD and were increased via AT1R blockade. e–p Peritoneal macrophages from ND mice were cultured with or without ox-LDL. e Adding ox-LDL to the culture-induced angiotensinogen and AT1R mRNAs. f, g ox-LDL loading increased ox-LDL levels (f) and mRNAs of the inflammatory cytokines IL-1β, TNFα, and VEGF (g) in the macrophages, which was suppressed by ARB. h In macrophages cultured without ox-LDL, AT1R KD repressed the cytokines. i ox-LDL loading induced ABCA1, and AT1R blockade further upregulated ABCA1. PPARγ and ELAVL1 were unchanged by ox-LDL and were upregulated by AT1R blockade. j AT1R KD upregulated ELAVL1, PPARγ, and ABCA1; k ELAVL1 KD repressed PPARγ and ABCA1, and l PPARγ KD repressed ABCA1. Under ELAVL1 KD (m), PPARγ KD (n), and ABCA1 KD (o) conditions, the cytokines were upregulated. p ABCA1 KD suppressed the lysosomal mRNAs of Lamp2, Lipa, and Atp6v1b2. q In the macrophages of ND mice, lipid loading induces PPARγ with the direct and/or indirect action of ELAVL1 to upregulate ABCA1 for sufficient efflux of cholesterol. However, in macrophages from HFD mice, excessive lipid loading activates AT1R, which suppresses ELAVL1, resulting in repression of PPARγ and relative suppression of ABCA1; thus, cholesterol efflux becomes insufficient. Resulting in cholesterol accumulation in the macrophages may further activate AT1R, prolonging the cycle. ND normal diet, HFD high-fat diet, AT1R angiotensin II type 1 receptor, ARB AT1R blocker. Respective numbers for ND mice treated with control, ND mice treated with ARB, HFD mice treated with control, and HFD mice treated with ARB were a 8 for each group; b 13, 8, 11, 13; c 10, 8, 10, 8; d 10, 8, 14, 14. e Respective numbers for control and ox-LDL + control were 8 and 11. f n = 8 for each group; h n = 12 for each group. i Respective numbers for control, ox-LDL, and oxLDL + ARB was 8, 10, 9. j–p n = 12 for each group. The samples were all biologically independent. Note that KD experiments were performed using siRNA and had no additional ox-LDL loading. Data are expressed as means ± standard deviation; *P < 0.05, **P < 0.01.