Interleukin-6 Receptor Signaling and Abdominal Aortic Aneurysm Growth Rates

Figures

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  Figure 1.. Sex- and age-adjusted change in abdominal aortic aneurysm growth rate (mm/y) per copy of the IL (interleukin)-6 minor allele.

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  Figure 2.. Anti-IL (interleukin)-6R prevents Ang II (angiotensin II)–induced hypertension but does not protect against aortic rupture induced by Ang II and anti-TGF (transforming growth factor)-β infusion. Mice were treated with anti-IL-6R or isotype control (n=22 mice/group) starting one week before Ang II and anti-TGF-β infusion. A, Plasma concentration of cytokines at day 0 (before Ang II and anti-TGF-β infusion) and day 7 to 14. *P<0.05 isotype vs anti-IL-6R; **P<0.01 isotype vs anti-IL-6R; 2-way ANOVA followed by uncorrected Fisher test. B, Plasma concentration of serum amyloid A (SAA) at day 0 (before Ang II and anti-TGF-β infusion) and day 7 to 14. ***P<0.05 isotype vs anti-IL-6R; 2-way ANOVA followed by uncorrected Fisher test. C, Systolic blood pressure measurement using tail cuff at day 0 and 7 after Ang II and anti-TGF-β infusion. ***P<0.001 isotype vs anti-IL-6R; 2-way ANOVA followed by uncorrected Fisher test. D, Survival curves of mice after Ang II and anti-TGF-β infusion. All data for the generation of the graphs shown in Figure 2 were generated in 2 independent experiments and then pooled together.

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  Figure 3.. Selective blockage of the IL (interleukin)-6 trans-signaling pathway using sgp130 in the Ang II (angiotensin II) + anti-TGF (transforming growth factor)-β model reduces aortic rupture. Mice were treated with sgp130Fc or human IgG1-Fc (Hum-Fc; n=10 mice/group) starting one week before Ang II and anti-TGF-β infusion. A, Plasma concentration of cytokines at day 0 (before Ang II and anti-TGF-β infusion) and day 7. *P<0.05 Hum-Fc vs sgp130; ***P<0.001 Hum-Fc vs sgp130; 2-way ANOVA followed by uncorrected Fisher test. B, Plasma concentration of serum amyloid A (SAA) at day 0 (before Ang II and anti-TGF-β infusion) and day 7. C, Systolic blood pressure measurement using tail cuff at day 0 and day 7 after Ang II and anti-TGF-β infusion. D, Survival curves of mice after Ang II and anti-TGF-β infusion. *P<0.05 Hum-Fc vs sgp130; Gehan-Breslow-Wilcoxon test. All data for the generation of the graphs shown in Figure 3 were generated in one independent experiment.

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  Figure 4.. Blockage of the IL (interleukin)-6 pathway using anti-IL-6R in the elastase + anti-TGF (transforming growth factor)-β model enhances T-cell infiltration and rupture of the aorta. Mice were treated with anti-IL-6R or isotype control (n=12 mice/group) starting one week before the application of elastase and the infusion anti-TGF-β. A, Survival curves of mice after the application of elastase and the infusion anti-TGF-β. *P<0.05 isotype vs anti-IL-6R; Gehan-Breslow-Wilcoxon test. B, Representative macroscopic pictures of abdominal aortic aneurysms from mice treated with elastase and anti-TGF-β and isotope or anti-IL-6R, at day 16. Note that the aneurysm from the isotype treated mouse was not ruptured. C, Analysis of the aortic diameter (µm) based on the perimeter obtained from aortic cross sections. D, Quantification and representative images of collagen content of the aortic wall analyzed using Sirius Red staining under polarized light. E and F, Quantification and representative images of myeloperoxidase (MPO) (D) and CD3 (E) immunofluorescent stainings on aortic cross section. *P<0.05 isotype vs anti-IL-6R; Mann-Whitney test. All data for the generation of the graphs shown in…

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  Figure 5.. Selective blockage of the IL (interleukin)-6 trans-signaling pathway using sgp130 in the elastase + anti-TGF (transforming growth factor)-β model increases collagen deposition and prevents aortic rupture. Mice were treated with sgp130 or Hum-Fc (n=12 mice/group) starting on the day of the application of elastase and the infusion anti-TGF-β. A, Survival curves of mice after the application of elastase and the infusion anti-TGF-β. *P<0.05 Hum-Fc vs sgp130; Gehan-Breslow-Wilcoxon test. B, Representative macroscopic pictures of abdominal aortic aneurysms from mice treated with elastase and anti-TGF-β and isotope or anti-IL-6R, at day 16. Note that the aneurysm from the Hum-Fc treated mouse was ruptured. C, Analysis of the aortic diameter (µm) based on the perimeter obtained from aortic cross sections. D, Quantification and representative images of collagen content of the aortic wall analyzed using Sirius Red staining under polarized light. *P<0.05 Hum-Fc vs sgp130; Mann-Whitney test. E and F, Quantification and representative images of lymphocyte antigen 6 complex, locus G (Ly6G) (D) and cluster of differentiation 3 (CD3) (E) immunofluorescent stainings on aortic cross-section. All…

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  Figure 6.. Overview of the IL (interleukin)-6 classical and trans-signaling pathways and their potential role in abdominal aortic aneurysm (AAA) growth. A, In classical IL-6 signaling (left), the binding of the cytokine IL-6 to the mIL-6R (membrane-bound IL-6 receptor) leads to the dimerization of its coreceptor gp130, and subsequently, triggers downstream signaling in a restricted subset of cells. In IL-6 trans-signaling (right), IL-6 forms a complex with sIL-6R (soluble IL-6 receptor) that can stimulate cells expressing gp130 even in the absence of mIL-6R. The minor allele of a functional variant in the IL6R gene, Asp358Ala (rs2228145 A>C) results in more efficient proteolytic cleavage of mIL-6R, thereby reducing levels of mIL-6R and classical IL-6 signaling but potentially increasing trans-signaling. B, In mouse models of AAA, the blockage of both the classical and trans-signaling pathways with anti-IL-6R (ie, MR16-1, the animal-equivalent of tocilizumab) did not have a conclusive effect on the time to aneurysm rupture. C, Specific blockage of the trans-signaling pathway with sgp130 resulted in improved survival rates in mouse models of AAA.