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Background: Aortic atherosclerosis and dissection cause significant morbidity and mortality. Although atherosclerosis is associated with aortic dissection, points of interaction are unclear. Regulator-of-G-protein signaling 5 (RGS5) is still insufficiently characterized regarding its role in aortic atherosclerosis and dissection. Objectives: We investigated Rgs5-deficiencie’s effects on aortic atherosclerosis and dissection. Methods: ApoE -/- Rgs5 GFP/GFP double knockout mice (rraa, n=15) and WT littermates (RRaa, n=17) were fed a cholesterol-rich diet for 14weeks. Plaque size, plaque morphology (composition and a validated vulnerability score based on Stary criteria), macrophage phenotype and aortic dissection were evaluated. Results: rraa mice displayed more aortic dissections (5/15) compared to WT (0/17; p2 -test). Surprisingly, rraa showed significantly smaller (rraa plaque size 190 657 μm 2 ± 93184 vs. control 398 279 μm 2 ± 153339) and less complicated plaques (5 of 15 mice with >2 vulnerability features) compared to RRaa (14 of 15 with >2 vulnerability features, p+ -myeloid cells revealed increased proportions of macrophages staining positive for pro-inflammatory markers (Cd86/Cd45: 24.71 area% ± 3.75 for RRaa; 60.95 area% ± 5.909, for rraa and iNOS/Cd45: 37.22 area% ± 6.37, for RRaa; 73.99 area% ± 3.997 for rraa, p Conclusions: rraa mice are more prone to aortic dissection despite smaller and less complex plaques with reduced anti-inflammatory but increased numbers of pro-inflammatory macrophages. We hypothesize that pro-inflammatory macrophage polarization along with evasion of anti-inflammatory macrophages in rraa mice could be causative for higher dissection numbers. Our data warrant further studies into the diverging pathomechanistic roles of Rgs5 in aortic dissection and atherosclerosis.

Myocardial infarction and stroke are frequent after surgical procedures and consume a considerable amount of benefit of surgical therapy. Perioperative stress, induced by surgery, is composed of hemodynamic and inflammatory reactions. The effects of perioperative stress on atherosclerotic plaques are ill-defined. Murine models to investigate the influence of perioperative stress on plaque stability and rupture are not available. We developed a model to investigate the influence of perioperative stress on plaque growth and stability by exposing apolipoprotein E-deficient mice, fed a high cholesterol diet for 7 weeks, to a double hit consisting of 30 minutes of laparotomy combined with a substantial blood loss (20% body weight; 400µl). The innominate artery was harvested 72 hours after the intervention. Control groups were sham and baseline controls. Interleukin-6 (IL-6) and Serum Amyloid A plasma levels were determined. Plaque load VSMC- and macrophage-content were quantified. Plaque stability was assessed using the Stary score and frequency of signs of plaque rupture. High-dose atorvastatin (80 mg/kg body weight/day) was administered for 6 days starting 3 days prior to double hit. A single dose of an IL-6-neutralizing antibody or the fusion protein sgp130-Fc selectively targeting IL-6 trans-signaling was subcutaneously injected. IL-6 plasma levels increased peaking at 6h after the intervention. SAA levels peaked at 24 hours (n=4, p Using this model, researchers will be able to further investigate the pathophysiology of perioperative plaque stability, which can result in myocardial infarction, and additionally, to test potential protective strategies.

Purpose: Plaque stability is governed by it's collagen content and VSMC phenotype1. RGS5, a GPCR modulator, has been shown to be associated with plaque stability3. RGS5 may moderate VSMC/endothelial cell interactions4. We examined if RGS5 expression is associated with plaque stability and detailed its role in VSMC/HUVEC behavior in vitro. Methods: With IRB permission, samples from 91 patients undergoing carotid thrombendarterectomy were collected and RNA was extracted. Target-PCRs for RGS5 were normalized for PCR efficiency and 3 housekeeping genes (GAPDH, ATPsynthase, Tubulin) using qBase software. RGS5 was downregulated in human VSMC or HUVEC by siRNA. After 24h, cells were incubated with mytomicin-C for 1 hour, and the confluent monolayer was wounded. Wound closure percentage after 20h, of scrambled vs. RGS5 siRNA transfected VSMCs was measured (ImageJ). HUVECs conditioned medium was used to perform VSMC scratch assays. RGS5 expression in resident vs. migrated VSMCs was assessed by collecting the cells that had migrated off a confluent coverslip. RNA was extracted for qRT-PCR. RGS5 expression was normalized by HPRT using the Δ(ΔCT) method. Scrambeled and RGS5 siRNA transfected HUVECs were cocultured with VSMCs to produce spheroids in a 96 well plate (1:1 ratio, 3000 cell/well). Spheroids structure was scored 24 hours later for HUVEC coverage, spheroid shape and size. Results: RGS5-RNA was increased in stable compared to unstable plaques (3.1±0.5 vs 1.6±0.3 CNRQ, n=91, p