Resolution of Inflammation Through the Lipoxin and ALX/FPR2 Receptor Pathway Protects Against Abdominal Aortic Aneurysms
Marcelo H. Petri, Silke Thul, Teodora Andonova, Moritz Lindquist-Liljeqvist, Hong Jin, Nikolaos-Taxiarchis Skenteris, Hildur Arnardottir, Lars Maegdefessel, Kenneth Caidahl, Mauro Perretti, Joy Roy and Magnus Bäck
Decreased Aortic Collagen and Increased Inflammatory Infiltrates in ApoE−/−×Fpr2−/− Mice and Reduced Neutrophil p38 Phosphorylation by the ALX/FPR2 Agonist ATL
(A) Total collagen of aortic aneurysmal lesions by Sirius red stain and orange (thick fibers)-to-green (thin fibers) ratio in ApoE−/−×Fpr2+/+(circles) and ApoE−/−×Fpr2−/−(squares) implanted with osmotic pumps containing Ang II (1 μg/kg/min). (Right) Micrographs of each genotype. (B) Levels of mRNA for MMP-9, MMP-2, Timp-1, and Timp-2 in aortae derived from either ApoE−/−×Fpr2+/+(circles) or ApoE−/−×Fpr2−/−(squares) mice. Six mice in each group, and graphs represent mean ± SEM. (C) Van Gieson elastic stain shows increased elastin breaks in ApoE−/−×Fpr2−/−. (D) Immunohistochemical quantifications of the neutrophil marker Ly6G in sections from abdominal aortas derived from either ApoE−/−×Fpr2+/+(circles) or ApoE−/−×Fpr2−/−(squares) mice treated with Ang II (1 μg/kg/min). n = 5 in each group, and graphs represent mean ± SEM; *p < 0.05. (E) Western blot analysis of bone marrow-derived neutrophils from either ApoE−/−×Fpr2+/+(filled circles) or ApoE−/−×Fpr2−/−(filled squares) mice. Cells were pretreated in the presence or absence of ATL (100 nM) before exposure to UV-C light to induce p38 phosphorylation. UV-induced p38 phosphorylation was significantly inhibited by pretreatment with ATL (100 nM) before UV exposure in neutrophils derived from ApoE−/−×Fpr2+/+(filled circles) but not in those derived from ApoE−/−×Fpr2−/−(filled squares). (Lower panel) Quantification of phosphorylated p38 in relation to total p38 was compared between UV-treated neutrophils in the absence and presence of ATL. Vinculin was used as a loading control. n = 3 in each group, and graphs represent mean ± SEM; *p < 0.05. ATL = aspirin-triggered lipoxin; AU = arbitrary unit; MMP = matrix metalloproteinase; UV = ultraviolet.