Laufs, U. | bioRxiv Science

bioRxiv2023

Membrane-bound Interleukin-1α mediates leukocyte adhesion during atherogenesis

BackgroundThe interleukin-1 (IL-1) family and the NLR family pyrin domain-containing 3 (NLRP3) inflammasome contribute to atherogenesis but the underlying mechanism are incompletely understood. Unlike IL-1{beta}, IL-1 is not dependent on the NLRP3 inflammasome to exert its pro-inflammatory effects. Here, a non-genetic model was applied to characterize the role of IL-1, IL-1{beta} and NLRP3 for the pathogenesis of atherosclerosis. MethodsAtherogenesis was induced by gain-of-function PCSK9-AAV8 mutant viruses and feeding of a high-fat western diet (WTD) for 12 weeks in C57Bl6/J wildtype mice (control) and in Il1a-/-, Nlrp3-/-, and Il1b-/- mice. ResultsIl1a-/- mice showed reduced atherosclerotic plaque area in the aortic root with lower lipid accumulation, while no difference was observed between wildtype, Nlrp3-/- and Il1b-/- mice. Serum proteomic analysis showed a reduction of pro-inflammatory cytokines (e.g. IL-1{beta}, IL-6) in Il1a-/- as well as in Nlrp3-/- and Il1b-/- mice. Bone marrow dendritic cells (BMDC) of WT, Nlrp3-/- and Il1b-/- mice and primary human monocytes showed translocation of IL-1 to the plasma membrane (csIL-1) upon stimulation with LPS. The translocation of IL-1 to the cell surface was regulated by myristoylation and increased in mice with hypercholesterolemia. CsIL-1 and IL1R1 protein-protein interaction on endothelial cells induced VCAM1 expression and monocyte adhesion, which was abrogated by the administration of neutralizing antibodies against IL-1 and IL1R1. ConclusionsIl1a-/- mice, but not Nlrp3-/- or Il1b-/- mice, are protected from atherosclerosis after induction of hypercholesterolemia independent of circulating cytokines. Myristoylation and translocation of IL-1 to the cell surface in myeloid cells facilitates leukocyte adhesion and contributes to the development of atherosclerosis. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/543077v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@c54814org.highwire.dtl.DTLVardef@1ff1971org.highwire.dtl.DTLVardef@df5605org.highwire.dtl.DTLVardef@889a1a_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstract.C_FLOATNO The role of cell-surface (cs) IL-1a in the initiation of atherosclerosis. C_FIG

immunology↗

bioRxiv2021

A novel non-genetic murine model of hyperglycemia and hyperlipidemia-associated accelerated atherosclerosis

ObjectiveAtherosclerosis, the main pathology underlying cardiovascular diseases is accelerated in diabetic patients. Genetic mouse models require breeding efforts which are time-consuming and costly. Our aim was to establish a new nongenetic model of inducible metabolic risk factors that mimics hyperlipidemia, hyperglycemia, or both and allows the detection of phenotypic differences dependent on the metabolic stressor(s). Methods and ResultsWild-type mice were injected with gain-of-function PCSK9D377Y (proprotein convertase subtilisin/kexin type 9) mutant adeno-associated viral particles (AAV) and streptozotocin and fed either a high-fat diet (HFD) for 12 or 20 weeks or a high-cholesterol/high-fat diet (Paigen diet, PD) for 8 weeks. To evaluate atherosclerosis, two different vascular sites (aortic sinus and the truncus of the brachiocephalic artery) were examined in the mice. Combined hyperlipidemic and hyperglycemic (HGHCi) mice fed a HFD or PD displayed characteristic features of aggravated atherosclerosis when compared to hyperlipidemia (HCi HFD or PD) mice alone. Atherosclerotic plaques of HGHCi HFD animals were larger, showed a less stable phenotype (measured by the increased necrotic core area, reduced fibrous cap thickness, and less -SMA-positive area) and had more inflammation (increased plasma IL-1{beta} level, aortic pro-inflammatory gene expression, and MOMA-2-positive cells in the BCA) after 20 weeks of HFD. Differences between the HGHCi and HCi HFD models were confirmed using RNA-seq analysis of aortic tissue, revealing that significantly more genes were dysregulated in mice with combined hyperlipidemia and hyperglycemia than in the hyperlipidemia-only group. The HGHCi-associated genes were related to pathways regulating inflammation (increased Cd68, iNos, and Tnfa expression) and extracellular matrix degradation (Adamts4 and Mmp14). When comparing HFD with PD, the PD aggravated atherosclerosis to a greater extent in mice and showed plaque formation after 8 weeks. Hyperlipidemic and hyperglycemic mice fed a PD (HGHCi PD) showed less collagen (Sirius red) and increased inflammation (CD68-positive cells) within aortic plaques than hyperlipidemic mice (HCi PD). HGHCi-PD mice represent a directly inducible hyperglycemic atherosclerosis model compared with HFD-fed mice, in which atherosclerosis is severe by 8 weeks. ConclusionWe established a nongenetically inducible mouse model allowing comparative analyses of atherosclerosis in HCi and HGHCi conditions and its modification by diet, allowing analyses of multiple metabolic hits in mice.

pharmacology and toxicology↗