Zhang_2024_J.Adv.Res__

INTRODUCTION: The N-terminal domain of angiopoietin-like protein 3 (ANGPTL3) inhibits lipoprotein lipase activity. Its C-terminal fibrinogen-like (FBN) domain is a ligand of macrophage integrin alphavbeta3. OBJECTIVES: ANGPTL3 might home to plaque where it directly regulates macrophage function via integrin alphavbeta3 for atherosclerosis progression. METHODS: Ldlr(-/-) mice on a high-fat diet and ApoE(-/-) mice on a chow diet were received adeno-associated virus (AAV)-mediated Angptl3 gene transfer and followed up for 12 weeks. ApoE(-/-) mice were injected AAV containing FLAG-tagged Angptl3 cDNA for tracing. Atherosclerotic features were compared between Angptl3(-/-)ApoE(-/-) mice and ApoE(-/-) littermates. THP-1 cells were exposed to 0 or 50 microg/ml ANGPTL3 FBN domain for 24 h to evaluate Toll-like receptor (TLR)4 expression using western blot analysis and circulating cytokine and chemokine profiles by the MILLIPLEX MAP assay. Phospho-proteomic profile was established in ANGPTL3-treated macrophages. Integrin beta3 deficient THP-1 cells were obtained by sgRNAs targeting RGD sequence using Lentivirus-Cas9 system. RESULTS: Angptl3 overexpression increased atherosclerotic progression and CD68(+) macrophages in plaque (p < 0.05 for all). By immunostaining, FLAG(+) cells were identified in plaque of gene transferred ApoE(-/-) mice. Fluorescent immunostaining detected co-localisation of Angptl3 and CD68 in plaque macrophages. Phospho-proteomic analysis revealed that Angptl3 induced phosphorylation of proteins that were involved in the IL-17 signalling pathway in THP-1 cells. In vitro, ANGPTL3 treatment increased the production of interleukin (IL)-1beta and tumour necrosis factor-alpha in THP-1 cells (p < 0.05 for both). Exposure of ANGPTL3 to THP-1 cells induced Akt phosphorylation which was weakened in integrin beta3 deficient ones. ANGPTL3 elevated TLR4 expression via Akt phosphorylation. In response to lipopolysaccharide, nuclear factor-kappaB activity was 2.2-fold higher in THP-1 cells pre-treated with ANGPTL3 than in untreated cells (p < 0.05). CONCLUSIONS: Targeting ANGPTL3 could yield a dual benefit of lowering lipid levels in the blood and suppressing macrophage activation in plaque.