腹主動脈瘤是一種慢性發炎血管疾病，當主動脈壁因結構受損而異常膨大，。目前已知的風險因素有高齡、男性與抽菸習慣，。主動脈有三層主要結構，分別為內層、中層與外層，平滑肌細胞為構成中層主要的細胞，在主動脈瘤發生時，往往會有平滑肌細胞流失、免疫細胞浸潤與彈性膜受損等現象發生。過去實驗室針對血管內皮細胞在動脈粥狀硬化的研究發現，CCN1(Cellular communication network factor 1)透過結合整合素(integrin)α6β1引起氧化壓力並造成發炎反應並促使更多的CCN1表現，然而CCN1是否參與在主動脈瘤的疾病進展與其角色目前尚不了解，因此，推測CCN1可能會透過相似的途徑參與主動脈瘤的病程中。首先，我們使用Ccn1+/LacZ小鼠（帶有LacZ報導基因之基因突變小鼠) 並透過氯化鈣誘導腹主動脈瘤的小鼠動物模式，探討在主動脈瘤的病程中CCN1表達之時間點參與細胞種類，在健康對照組中，腹主動脈是不表現CCN1，然而我們發現於誘導主動脈瘤發生後的早期（誘導後3至7天），CCN1由平滑肌細胞大量表達，也有發現部分內皮細胞與巨噬細胞有表達CCN1；於誘導主動脈瘤發生後的中後期（誘導後14至28天），於血管外觀上CCN1呈現點狀的表現在特殊的位置，在後續切片中發現這些點都有基質重組發生，CCN1主要也是由平滑肌細胞表達。因此我們推測CCN1參與主動脈瘤的病程發展並且和平滑肌細胞在其中扮演重要角色。為了探討CCN1參與在主動脈瘤中的作用，我們使用Ccn1dm/dm小鼠（於CCN1上有兩處突變位點之基因位點突變小鼠)，於Ccn1有此兩處突變造成CCN1蛋白無法與整合素?6?1結合之小鼠，並透過氯化鈣誘導腹主動脈瘤的小鼠動物模式，探討在抑制結合的狀況下，CCN1在主動脈瘤病程中扮演的角色。於28天的動物模式中我們發現，當阻止的CCN1和整合素?6?1結合的情況下，發現有減少平滑肌細胞的流失、組織的重組的狀況也較不嚴重，並且也有較少巨噬細胞浸潤的現象。因此我們想知道在早期，CCN1大量表現的時期，CCN1如何調節並參與主動脈瘤的發生，因此我們使用Ccn1dm/dm小鼠並選擇在第七天觀察組織的發炎反應與氧化壓力，於第七天時，Ccn1dm/dm相較於控制組在平滑肌細胞中有明顯降低發炎因子TNF-α與IL-1β的表現，並且也有降低氧化壓力的現象，。因此我們推測，綜合上述結果顯示CCN1於透過結合整合素?6?1提升氧化壓力與發炎反應參與導致主動脈瘤的病程的進展，未來可發展為治療主動脈瘤的標的。

Abdominal aortic aneurysm (AAA) is a chronic vascular disease, characterized by aortic bulges and with a high mortality rate due to aortic rupture. Vascular smooth muscle cell (VSMC) loss, extracellular matrix degradation, vascular inflammation and oxidative stress are the known processes in AAA pathogenesis. Our lab previously identified the matricellular protein CCN1 (Cellular communication network factors 1) as an atherogenic factor through promoting inflammation and oxidative stress in the arterial wall, the same risk factors for AAA. CCN1 promotes VSMC adhesion and chemotaxis through integrin ?6?1. We hypothesized that CCN1 induces AAA through elevating oxidative stress and inflammation by engaging integrin ?6?1. We induced aneurysm by periaortic application of 0.5 M CaCl2 for 15 mins, then washed with saline. CCN1 expression in AAA formation was examined in Ccn1+/LacZ mice, which carry a lacZ reporter gene knocked-in to be driven by the Ccn1 promoter. After induction of aneurysm, aortae were whole-mount X-gal stained to reveal CCN1 expression. We found that CCN1 was highly induced in VSMCs during the early stages (3 and 7 days) of aneurysm formation. CCN1 expression became lower after the mid stage (14 to 28 days). CCN1 expression was found at the breakages of tunica media, suggesting a correlation between CCN1 and AAA formation. To explore the role of CCN1 in AAA, Ccn1dm/dm mice, carrying the ?6?1-binding-defective CCN1 mutant CCN1-DM, were used in the AAA mouse model. We found that the CaCl2-induced aneurysm AAA formation was inhibited in Ccn1dm/dm mice comparing with the wild-type controls, suggesting that CCN1 is associated with aneurysm formation through integrin ?6?1. The disruption of elastic membranes is a common feature of aneurysm. We observed more break points of medial elastic membranes in WT mice while the elastincomparing to the better maintained elastic membranes in Ccn1dm/dm mice maintained better structural integrity. 28 days after CaCl2 treatment, VSMCs were significantly eliminated in the tunica media of WT aortas, and collagen fibers were disintegrated. In contrast, Ccn1dm/dm mice preserved the majority of VSMCs and collagen matrix. To examine calcification, alizarin red staining (ARS) was performed. The tunica media of WT mice developed severe calcification. Though the media of Ccn1dm/dm mice was also calcified, the structure remained compactintact. To examine the CCN1 involvement in the early-stage aneurysm formation, aortae were harvested 7 days after CaCl2 treatment, Ccn1dm/dm was found decreased thewith less inflammatory cytokines, TNF-α and IL-1β, and lower levels of oxidative stress in VSMCs. We provide evidencefound that CCN1 induced by CaCl2calcium promotes aneurysm formation through binding to integrin ?6?1 in mice. CCN1/?6?1 engagement potentially can be developed as a therapeutic target for AAA.

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