Hyperlipidemia does not affect development of elastase-induced abdominal aortic aneurysm in mice

Abstract

Background and aims: Hyperlipidemia is a suggested risk factor for abdominal aortic aneurysm (AAA). However, whether hyperlipidemia is causally involved in AAA progression remains elusive. Here, we tested the hypothesis that hyperlipidemia aggravates AAA formation in the widely used porcine pancreatic elastase (PPE) model of AAA in mice with varying levels of plasma lipids. Methods: Prior to PPE-surgery, 8-week-old male C57BL/6J mice (n = 32) received 1⋅10 11 viral genomes of rAAV8-D377Y-mPcsk9 or control rAAV8 via the tail vein. Mice were fed either western type diet or regular chow. At baseline and during the 28 days following PPE-surgery, mice underwent weekly ultrasonic assessment of AAA progression. Experiments were repeated using Apolipoprotein E knockout (ApoE − /− ) mice (n = 7) and wildtype C57BL/6J mice (n = 5). Results: At sacrifice, maximal intergroup plasma cholesterol and non-HDL/HDL ratio differences were >5-fold and >20-fold, respectively. AAA diameters expanded to 150% of baseline, but no intergroup differences were detected. This was verified in an independent experiment comparing 8-week-old male ApoE − /− mice with wildtype mice. Histological evaluation of experimental AAA lesions revealed accumulated lipid in neointimal and medial layers, and analysis of human AAA lesions (n = 5) obtained from open repair showed medial lipid deposition. Conclusions: In summary, we find that lipid deposition in the aortic wall is a feature of PPE-induced AAA in mice as well as human AAA lesions. Despite, our data do not support the hypothesis that hyperlipidemia contributes to AAA progression.

Basement membrane collagen IV deficiency promotes abdominal aortic aneurysm formation

“…Preparation of samples for mass spectrometry have been described previously 17 . Snap frozen unchallenged aortas or formalin-fixed AAA segments from mice were homogenized using a TissueLyser system (Qiagen) with stainless steel beads (Qiagen) in a lysis buffer [100 mM DTT, 5% sodium deoxycholate, 1% β-octylglucoside, 20 mM Tris, pH 8.8, supplemented with complete, Mini, EDTA-free Protease Inhibitor Cocktail Tablets and PhosSTOP (Roche)].…”

“…For explorative proteomics of mouse aortas, samples (4 µg tryptic peptides per sample) were randomly labelled with 10-plex tandem mass tags (TMT, Thermo Scientific) and combined into 2 × 3 samples, high-pH fractionated, and analyzed by nano-LC–MS/MS virtually as previously described 17 .…”

A paradoxical increase of force development in saphenous and tail arteries from heterozygous ANO1 knockout mice

“…Tagged peptide samples were mixed and subsequently fractionated by high‐pH reversed phase liquid chromatography and analyzed by reversed phase nano‐liquid chromatography tandem mass spectrometry (RP‐nanoLC‐MSMS). In brief, the tagged peptide samples were combined, lyophilized, purified, and fractionated into five fractions by high pH liquid chromatography virtually as previously described (Mulorz et al., 2020). Fractions were analyzed in triplicates by RP‐nanoLC‐MS/MS analysis on an Orbitrap Eclipse mass spectrometer (Thermo Fisher Scientific) equipped with a nanoHPLC interface (Dionex UltiMate 3000 nano HPLC).…”

“…Fractions were analyzed in triplicates by RP‐nanoLC‐MS/MS analysis on an Orbitrap Eclipse mass spectrometer (Thermo Fisher Scientific) equipped with a nanoHPLC interface (Dionex UltiMate 3000 nano HPLC). Briefly, samples were separated also as previously described (Mulorz et al., 2020). Mass spectra of eluting peptides were acquired in positive ion mode applying automatic data‐dependent switch between an Orbitrap survey MS scan in the mass range of 400–1,200 m/z followed by peptide fragmentation applying a normalized collisional energy of 40% in a 3‐s duty cycle.…”

“…Ion selection threshold was set to 25,000 counts. Selected sequenced ions were dynamically excluded for 60 s. All raw data files were processed and quantified using Proteome Discoverer version 2.4 (Thermo Scientific) also as previously described (Mulorz et al., 2020).…”