Activation of transglutaminase type 2 for aortic wall protection in a rat abdominal aortic aneurysm formation.
The altered structure and composition of the vascular extracellular matrix (ECM) influences the formation of abdominal aortic aneurysms (AAA). Transglutaminase type 2 (TG2), which is a Ca(2+)-dependent cross-linking enzyme, has been proven the importance for ECM homeostasis, but there is no evidence of TG2 in AAA formation. The hypothesis was investigated that TG2 contributes to protect aortic walls during remodeling of the AAAs.
In a rat abdominal aortic aneurysm model using a combination of intraluminal elastase infusion and extraluminal calcium chloride, TG2 expression and activity were evaluated at 1 and 8 weeks after the AAA preparation (n = 6 at each endpoint), compared with those of the non-prepared aorta (n = 6). Additionally, ex vivo experiments of isolated AAA tissue culture with recombinant human TG2, TG2 inhibitor cystamine, or tissue necrosis factor (TNF)-α were performed.
TG2 mRNA expression in the AAAs was significantly upregulated at both 1 and 8 weeks (22.4-fold and 5.4-fold increases of the non-prepared aorta, P = .0022 and P = .0048, respectively). TG2 protein expression and activity were also enhanced by fluorescent staining of the AAAs. Similar mRNA upregulation of TNF-α, interleukin-1β, matrix metalloproteinases (MMP)-2, MMP-9, and tissue inhibitors of metalloproteinases (TIMP)-1 and TIMP-2 was observed in the AAAs, and TG2 and TNF-α were colocalized in the aortic walls at 1 week. Ex vivo experiments showed that mRNA expressions of TNF-α, MMP-2, and MMP-9 in the cultured AAA tissue were decreased by exogenous TG2, whereas were increased by cystamine. TNF-α exposure to the AAA tissues was significantly upregulated TG2 mRNA expression (P = .0333).
TG2 expression and activity in AAA formation were enhanced, possibly due to compensatory reaction. TG2 has a potential role of ECM protector in aortic walls during remodeling of the AAAs.
Munezane T
，Hasegawa T
，Suritala
，Tanaka A
，Okada K
，Okita Y
... -
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Free-radical scavenger edaravone inhibits both formation and development of abdominal aortic aneurysm in rats.
An ideal pharmaceutical treatment for abdominal aortic aneurysm (AAA) is to prevent aneurysm formation and development (further dilatation of pre-existing aneurysm). Recent studies have reported that oxidative stress with reactive oxygen species (ROS) is crucial in aneurysm formation. We hypothesized that edaravone, a free-radical scavenger, would attenuate vascular oxidative stress and inhibit AAA formation and development.
An AAA model induced with intraluminal elastase and extraluminal calcium chloride was created in 42 rats. Thirty-six rats were divided three groups: a low-dose (group LD; 1 mg/kg/d), high-dose (group HD; 5 mg/kg/d), and control (group C, saline). Edaravone or saline was intraperitoneally injected twice daily, starting 30 minutes before aneurysm preparation. The remaining six rats (group DA) received a delayed edaravone injection (5 mg/kg/d) intraperitoneally, starting 7 days after aneurysm preparation to 28 days. AAA dilatation ratio was calculated. Pathologic examination was performed. ROS expression was semi-quantified by dihydroethidium staining and the oxidative product of DNA induced by ROS, 8-hydroxydeoxyguanosine (8-OHdG), by immunohistochemical staining.
At day 7, ROS expression and 8-OHdG-positive cells in aneurysm walls were decreased by edaravone treatment (ROS expression: 3.0 ± 0.5 in group LD, 1.7 ± 0.3 in group HD, and 4.8 ± 0.7 in group C; 8-OHdG-positive cells: 106.2 ± 7.8 cells in group LD, 64.5 ± 7.7 cells in group HD, and 136.6 ± 7.4 cells in group C; P < .0001), compared with group C. Edaravone treatment significantly reduced messenger RNA expressions of cytokines and matrix metalloproteinases (MMPs) in aneurysm walls (MMP-2: 1.1 ± 0.5 in group LD, 0.6 ± 0.1 in group HD, and 2.3 ± 0.4 in group C; P < .001; MMP-9: 1.2 ± 0.1 in group LD, 0.2 ± 0.6 in group HD, and 2.4 ± 0.2 in group C; P < .001). At day 28, aortic walls in groups LD and HD were less dilated, with increased wall thickness and elastin content than those in group C (dilatation ratio: 204.7% ± 16.0% in group C, 156.5% ± 6.6% in group LD, 136.7% ± 2.0% in group HD; P < .0001). Delayed edaravone administration significantly prevented further aneurysm dilatation, with increased elastin content (155.2% ± 2.9% at day 7, 153.1% ± 11.6% at day 28; not significant).
Edaravone inhibition of ROS can prevent aneurysm formation and expansion in the rat AAA model. Free-radical scavenger edaravone might be an effective pharmaceutical agent for AAA in clinical practice.
Morimoto K
，Hasegawa T
，Tanaka A
，Wulan B
，Yu J
，Morimoto N
，Okita Y
，Okada K
... -
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Controlled release of ascorbic acid from gelatin hydrogel attenuates abdominal aortic aneurysm formation in rat experimental abdominal aortic aneurysm model.
Abdominal aortic aneurysms (AAAs) are associated with oxidative stress and inflammatory response. We investigated the hypothesis that the known antioxidant ascorbic acid, which can also promote elastin and collagen production by smooth muscle cells, would prevent AAA formation in a rat model.
An intraluminal elastase and extraluminal calcium chloride-induced rat AAA model was used, and the animals were divided into three groups: control (group C, n = 18), the aorta wrapped with a saline-impregnated gelatin hydrogel sheet (group G, n = 18), and the aorta wrapped with a gelatin hydrogel sheet incorporating ascorbic acid (group A, n = 18). Wrapping of the sheet was completed at the end of treatment for AAA creation. The aortic dilatation ratio was measured, and aortic tissues were further examined for oxidative stress and oxidative DNA damage using biochemical and histologic techniques.
Aortic dilatation at both 4 and 8 weeks was inhibited in group A (dilatation ratio [%] at 4 weeks: 186.2 ± 21.8 in group C, 152.3 ± 10.2 in group G, 126.8 ± 11.6 in group A; P < .0001; dilatation ratio [%] at 8 weeks: 219.3 ± 37.5 in group C, 194.0 ± 11.6 in group G, 145.7 ± 8.3 in group A; P = .0002). Elastin and collagen content were significantly preserved in group A (elastin, P = .0015; collagen, P < .0001). The messenger RNA expressions of matrix metalloproteinase (MMP)-9, monocyte chemotactic protein-1, interleukin-1β, and tissue necrosis factor-α (P = .0024, P < .0001, P < .0001, and P < .0001, respectively) were downregulated in group A (P = .0024), whereas tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 were both upregulated in group A (TIMP-1, P = .0014; TIMP-2, P < .0001). Gelatin zymography showed activities of pro-MMP-2, MMP-2, and MMP-9 were significantly suppressed in group C (P < .0001 for each). Reactive oxygen species expression and 8-hydroxydeoxyguanosine and cluster of differentiation 68 staining were significantly suppressed in group A (reactive oxygen species expression, P < .0001; 8-hydroxydeoxyguanosine-positive cells, P < .0001; cluster of differentiation 68 positive cells, P < .0001).
Controlled release of ascorbic acid using gelatin hydrogel sheet-attenuated AAA formation through antioxidant and anti-inflammatory effect, regulation of MMP-2, TIMP-1, and TIMP-2, and preserving elastin and collagen in this animal model.
Tanaka A
，Hasegawa T
，Morimoto K
，Bao W
，Yu J
，Okita Y
，Tabata Y
，Okada K
... -
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A Novel Modification of the Murine Elastase Infusion Model of Abdominal Aortic Aneurysm Formation.
To create a novel procedure that will decrease the mortality of experimental animals in the intraarterial infusion of elastase abdominal aortic aneurysm (AAA) model.
Novel models were created by means of direct puncture in the infrarenal abdominal aortic aorta, intraluminal elastase in the 1-cm segment of abdominal aorta. Femoral artery cannula approach and infusing with elastase was considered as the traditional group and that infusing with saline solution as the control group. Survival rate, morphology and histology of aneurysms, and inflammation mediators were calculated.
Among the 36 rats, the average length from testicular arteries to left iliolumbar artery was 1.18 ± 0.22 cm, and 77.8% of them were longer than 1 cm. Procedure time was significantly shorter in novel group than that in 2 other groups (P = 0.006; P < 0.0001). During 24 hr postoperation, no death was observed in the novel group. Within 4 wk, survival rate in the control group was 60.6% and 80.8% in the novel group whereas 41.0% in the traditional group. Till the second week, all rats in the traditional and novel group had formed AAAs. And then, the survival rates and rupture rates of AAA between the 2 groups were similar within the following 2 wk (P = 0.487; P = 0.539). Inflammation degree and elastase content in intima media of aneurysms were similar (P = 0.720). However, Tumor necrosis factor alpha and Interleukin-1 beta levels were significantly lower in the novel group than those in the traditional group (P < 0.0001; P < 0.0001).
A novel rat AAA model was created by intraluminal elastase infusion through direct puncture the infrarenal aorta. This model is efficient and reliable, with a high survival rate and with similar morphology and histology of aortic aneurysms.
Hu G
，Dong Z
，Fu W
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ResearchGate
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