Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Sep:85:358-370.
doi: 10.1016/j.avsg.2022.05.024. Epub 2022 Jun 6.

Genetic and Pharmacological Disruption of Interleukin-1α Leads to Augmented Murine Aortic Aneurysm

Morgan Salmon  1 , Robert B Hawkins  2 , Jolian Dahl  3 , Erik Scott  3 , W Forrest Johnston  4 , Gorav Ailawadi  2
Affiliations

Genetic and Pharmacological Disruption of Interleukin-1α Leads to Augmented Murine Aortic Aneurysm

Morgan Salmon et al. Ann Vasc Surg. 2022 Sep.

Abstract

Background: Interleukin-1 (IL-1) signaling has an established role as a cytokine signaling pathway important for progression of abdominal aortic aneurysms (AAAs). While the IL-1β ligand and IL-1R1 have been previously investigated, the role of the IL-1α ligand in AAAs remains unknown. In this study, we sought to examine the role of IL-1α in AAAs using genetic and pharmacologic approaches.

Methods: Eight-week-old wild-type (WT) or IL-1α knock-out (KO) male and female mice (n = 10-16/group) underwent experimental AAA and were harvested 14 days following surgery to assess AAA size and characteristics. In separate studies, 8-week-old WT mice were treated with an inhibitor to IL-1α during AAA formation and harvested 14 days following surgery. Finally, WT and IL-1α KO mice were administered Anakinra, an IL-R1 inhibitor, during AAA formation to determine the effect of inhibiting IL-1R1 when IL-1α is knocked out.

Results: Male and female IL-1α KO mice had larger AAAs compared to WT AAAs (male: 153% vs. 89.2%, P = 0.0001; female: 86.6% vs. 63.5%, P = 0.02). IL-1α KO mice had greater elastin breakage (P = 0.01), increased levels of macrophage staining (P = 0.0045), and greater pro-metallo proteinase 2 (P = 0.02). Pharmacologic inhibition of WT male mice with an IL-1α neutralizing antibody resulted in larger AAAs (133.1% vs. 77.0%, P < 0.001). Finally, treatment of IL-1α KO male mice with Anakinra decreased AAA formation compared with vehicle control AAAs (Anakinra + IL-1α KO: 47.7% vs. WT: 147.1%; P = 0.0001).

Conclusions: IL-1α disruption using either genetic or pharmacologic approaches worsens AAAs.

PubMed Disclaimer

Figures

Fig. 1.
Fig. 1.
Male and female IL-1α knock-out mice demonstrated augmented AAA formation in comparison to wild-type mice in a topical elastase AAA model. (A) Schematic of the experiment approach used to investigate IL-1α elimination in AAAs. (B) Schematic of the topical elastase surgical model and groups used in the genetic mouse knock-out studies. (C) WT (n = 13/group) and IL-1α (n = 16/group) male mice were harvested 14 days following topical elastase AAA formation and aortic dilation data were measured (P < 0.001; WT: 89.19 ± 5.835% versus IL-1α: 153.0 ± 14.13%). (D) WT (n = 11/group) and IL-1α (n = 10/group) female mice were also harvested 14 days following topical elastase AAA formation and aortic dilation was measured (P = 0.02; WT: 64.36 ± 4.645 versus IL-1α: 86.60 ± 6.138). (E) Male and female human AAA samples (n = 6/group) were embedded, paraffin section and stained for IL-1α, and quantified to determine whether IL-1α is gender dependent in human AAAs.
Fig. 2.
Fig. 2.
IL-1α knock-out mice demonstrated increased elastin degradation, endothelial cell, and macrophage staining following topical elastase AAA formation. (A) Male WT and IL-1α knock-out mice (n = 5–10/group) were harvested, fixed with 4% paraformaldehyde, paraffin embedded, and stained separately for VVG stain, LGAL3, Ly-6B, SM-actin, CD3, CD31, S100A4, cleaved caspase 3 or Ki67, and counter-stained with hematoxylin. Staining demonstrated increased elastin breaks (P = 0.01, n = 5–10/group), increased macrophage staining (LGAL3; P = 0.05, n = 5–10/group), increased SM-actin staining (SM-actin; P = 0.0091, n = 5–10/group), and increased endothelial cell staining (CD31; P = 0.007, n = 5–10/group) in the IL-1α KO mice. (B) Pro-MMP9 levels in WT and IL-1α knock-out mice were measured using gelatin zymography (n = 4–6/group). MMP9 levels were measured using gelatin zymography (n = 4–6/group). (C) Pro-MMP2 levels were measured using gelatin zymography (65,431 vs. 187,315 densitometry units, P = 0.0279, n = 4–6/group). MMP2 levels were measured in WT and IL-1α knock-out male mice using gelatin zymogram (1,825 vs. 155,721 densitometry units, P = 0.007, n = 4–6/group).
Fig. 3.
Fig. 3.
Pharmacologic inhibition of IL-1α in WT male mice demonstrated increased aortic dilation and increased SM-actin and S100A4 expression. (A) Schematic of the topical elastase surgical model and groups used in the IL-1α pharmacologic mouse inhibition studies. (B) WT (n = 12/group) male mice underwent topical elastase application and underwent injections of either an IL-1α antibody or IgG antibody on days 2, 4, 6, 8, 10, and 12 following surgery. Male mice were harvested 14 days following topical elastase AAA formation and aortic dilation data were measured (P < 0.001; IgG antibody: 77.03 ± 6.061% versus IL-1α antibody: 133.1 ± 17.32%). (C) Following harvest, a subset was analyzed for immunohistochemical analysis using VVG, LGAL3, Ly-6B, SM-actin, CD-3, CD31, S100A4, cleaved caspase 3, or Ki67 staining. VVG staining demonstrated a trend toward increased elastin breaks (P = 0.0801, n = 5–6/group), as did SM-actin (P = 0.0301, n = 5–6/group), S100A4 (P = 0.01, n = 5–6/group), and Ki67 (P = 0.01, n = 5–6/group), whereas LGAL3, CD3, Ly-6B, CD31, and cleaved caspase 3 exhibited no change (n = 5–6/group).
Fig. 4.
Fig. 4.
Genetic inhibition of IL-1α in male mice demonstrated increased IL-1b, IL-1R1, and IL-6 staining 14 days following AAA formation. (A) IL-1a, IL-1b, and IL-1R1 were stained via immunohistochemistry in control mice without surgery (n = 6/group) and WT mice that underwent elastase application to the abdominal aorta and harvest 14 days later (n = 6/group). (B) IL-1a, IL-1b, and IL-1R1 were measured via ELISA in control mice without surgery (n = 8/group) and WT AAA mice harvested at 14 days post AAA surgery (n = 11/group). (C) IL-1a, IL-1b, IL-1R1 knock-out, and WT (n = 5/group) male mice underwent elastase AAA surgeries. Male mice were harvested 14 days following topical elastase AAA formation, fixed in PFA and stained for IL-1a, IL-1b, IL-1R1, and IL-6 and results were quantified. (D) Serum was analyzed from WT and IL-1a male mice (n = 5/group) harvested 14 days following AAA formation for IL-1b and IL-1a. (E) Separately, serum was analyzed from WT male mice injected with either IgG or IL-1a antibody (n = 5/group) and harvested 14 days following AAA formation for IL-1b and IL-1a.
Fig. 5.
Fig. 5.
Pharmacologic inhibition of IL-1R1 using Anakinra in IL-1α knock-out mice demonstrates decreased aortic dilation and decreased elastin breaks. (A) Schematic of the topical elastase surgical model and groups used in the WT and IL-1a knock-out pharmacologic mouse inhibition studies. (B) WT (n = 11/group) and IL-1α knock-out (n = 4/group) male mice underwent topical elastase application and underwent injections of either an Anakinra (100 mg/kg) or vehicle control daily (100 mg/kg). Male mice were harvested 14 days following topical elastase AAA formation and aortic dilation data were measured (vehicle antibody: 147.1 ± 24.47 % versus Anakinra: 51.35 ± 24.46% versus IL-1α knock-out plus Anakinra: 47.68 ± 8.628%; P = 0.0001 vehicle versus Anakinra per Student’s t-test; P = 0.0016 vehicle versus IL-1α knock-out plus Anakinra per Student’s t-test). (C) Following harvest, a subset was analyzed for immunohistochemical analysis using VVG staining.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

References

    1. Lindholt JS, Vammen S, Juul S, et al. The validity of ultrasonographic scanning as screening method for abdominal aortic aneurysm. Eur J Vasc Endovasc Surg 1999;17:472–5. - PubMed
    1. Norman PE, Semmens JB, Lawrence-Brown MMD. Long-term relative survival following surgery for abdominal aortic aneurysm: a review. Cardiovasc Surg 2001;9:219–24. - PubMed
    1. Scott RA, Wilson NM, Ashton HA, et al. Influence of screening on the incidence of ruptured abdominal aortic aneurysm: 5-year results of a randomized controlled study. Br J Surg 1995;82:1066–70. - PubMed
    1. Scott RAP, Bridgewater SG, Ashton HA. Randomized clinical trial of screening for abdominal aortic aneurysm in women. Br J Surg 2002;89:283–5. - PubMed
    1. Kontopodis N, Pantidis D, Dedes A, et al. The - not So - Solid 5.5 cm threshold for abdominal aortic aneurysm repair: facts, misinterpretations, and future directions. Front Surg 2016;3:1. - PMC - PubMed

MeSH terms