Cholesterol accumulation in macrophages drives NETosis in atherosclerotic plaques via IL-1β secretion

• Published in: Cardiovascular research 2023-05, Vol.119 (4), p.969-981
• Main Authors: Yalcinkaya, Mustafa, Fotakis, Panagiotis, Liu, Wenli, Endo-Umeda, Kaori, Dou, Huijuan, Abramowicz, Sandra, Xiao, Tong, Libby, Peter, Wang, Nan, Tall, Alan R, Westerterp, Marit
• Format: Article
• Language: English
• Subjects: Animals; Cholesterol - metabolism; Inflammasomes - metabolism; Macrophages - metabolism; Mice; Mice, Knockout; NLR Family, Pyrin Domain-Containing 3 Protein - genetics; NLR Family, Pyrin Domain-Containing 3 Protein - metabolism; Original; Plaque, Atherosclerotic - metabolism
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1093/cvr/cvac189

Abstract Aims Neutrophil extracellular trap formation (NETosis) increases atherosclerotic plaque vulnerability and athero-thrombosis. However, mechanisms promoting NETosis during atherogenesis are poorly understood. We have shown that cholesterol accumulation due to myeloid cell deficiency of the cholesterol transporters ATP Binding Cassette A1 and G1 (ABCA1/G1) promotes NLRP3 inflammasome activation in macrophages and neutrophils and induces prominent NETosis in atherosclerotic plaques. We investigated whether NETosis is a cell-intrinsic effect in neutrophils or is mediated indirectly by cellular crosstalk from macrophages to neutrophils involving IL-1β. Methods and results We generated mice with neutrophil or macrophage-specific Abca1/g1 deficiency (S100A8CreAbca1fl/flAbcg1fl/fl or CX3CR1CreAbca1fl/flAbcg1fl/fl mice, respectively), and transplanted their bone marrow into low-density lipoprotein receptor knockout mice. We then fed the mice a cholesterol-rich diet. Macrophage, but not neutrophil Abca1/g1 deficiency activated inflammasomes in macrophages and neutrophils, reflected by caspase-1 cleavage, and induced NETosis in plaques. NETosis was suppressed by administering an interleukin (IL)-1β neutralizing antibody. The extent of NETosis in plaques correlated strongly with the degree of neutrophil accumulation, irrespective of blood neutrophil counts, and neutrophil accumulation was decreased by IL-1β antagonism. In vitro, IL-1β or media transferred from Abca1/g1-deficient macrophages increased NETosis in both control and Abca1/Abcg1 deficient neutrophils. This cell-extrinsic effect of IL-1β on NETosis was blocked by an NLRP3 inhibitor. Conclusion These studies establish a new link between inflammasome-mediated IL-1β production in macrophages and NETosis in atherosclerotic plaques. Macrophage-derived IL-1β appears to increase NETosis both by increasing neutrophil recruitment to plaques and by promoting neutrophil NLRP3 inflammasome activation. Graphical Abstract Graphical abstract