Figure 1. Trem1 genetic deletion reduces aneurysm development in angiotensin II–induced AAA.

(A) Hypercholesterolemic Apoe^–/– mice were implanted with subcutaneous osmotic minipumps infusing PBS (control group) or AngII (1000 ng/kg/min). Quantification of Trem1 mRNA expression in the aorta at day 3 by RT-qPCR (n = 6 in PBS-infused group; n = 5 in AngII-infused group). (B) Immunofluorescence staining in the aortic wall of PBS- (left) or AngII-infused (right) animals at day 3, DAPI (blue), TREM-1 (red), and CD68 (green). Scale bars: 50 μm. (C) Apoe^–/–Trem1^+/+ and Apoe^–/–Trem1^–/– mice were implanted with subcutaneous osmotic minipumps infusing AngII (1000 ng/kg/min). Analyses were done at different time points following AngII infusion. (D) TREM-1 expression on circulating CD11b⁺Ly6G^– monocytes of Apoe^–/–Trem1^+/+ (pink) and Apoe^–/–Trem1^–/– mice (black) at day 3 after AngII infusion. (E) Quantitative analysis and representative photomicrographs of the maximal aortic diameter at day 28 (n = 11 in Apoe^–/–Trem1^+/+ group, n = 9 in Apoe^–/–Trem1^–/– group). Scale bars: 1 mm. (F) Quantification of the number of elastin layers in the aortic wall by orcein staining at day 7 (n = 7/group). Scale bars: 50 μm. (G) FMT quantification of MMP-2, -3, -9, and -13 activity in aorta at day 7 (n = 4 in Apoe^–/–Trem1^+/+ group, n = 3 in Apoe^–/–Trem1^–/– group). (H) Quantification of Il1b, Tnfa, Mmp2, and Mmp9 mRNA expression in aorta at day 7 by RT-qPCR (n = 9 in Apoe^–/–Trem1^+/+ group, n = 6 in Apoe^–/–Trem1^–/– group). (I) Quantification and representative photomicrographs of CD68⁺ macrophages in the aorta at day 7 (n = 7/group). Scale bars: 50 μm. (J) Flow cytometry quantification of Ly6C^hi classical monocyte infiltration in the aortic wall at day 3 (n = 5 in each group). (K) Flow cytometry quantification of circulating Ly6C^hi classical monocytes at day 3 (n = 8 in Apoe^–/–Trem1^+/+ group, n = 7 in Apoe^–/–Trem1^–/– group). Kruskal-Wallis test, Mann-Whitney test; *P < 0.05, ** P < 0.01, ***P < 0.001.