Delayed enhancement on computed tomography in abdominal aortic aneurysm wall.

The purpose of this study was to evaluate delayed enhancement (DE) of the aortic wall of atherosclerotic aneurysms using computed tomography and to evaluate the relationships between DE and wall thickness of abdominal aortic aneurysm (AAA), diameter of AAA, serum levels of C-reactive protein (CRP) which indicate inflammation status, and pathological findings. Computed tomographic images of atherosclerotic AAA in 110 patients were studied between July 2001 and March 2003. Computed tomography (CT) scanning included unenhanced, enhanced early, and enhanced delayed phases. Pathological findings were obtained from 19 of the 110 patients. We determined DE of the AAA wall and assessed the association between DE and AAA wall thickness, AAA diameter, serum levels of CRP, and pathological findings. Delayed enhancement on CT was demonstrated in 66 of 110 patients with atherosclerotic AAA (60.0%). Patients with DE demonstrated significantly larger AAA diameter (4.8 +/- 0.9 versus 3.9 +/- 0.6 cm, P < 0.0001) and significantly higher levels of CRP (5.0 +/- 6.0 versus 2.3 +/- 2.9 mg/l, P = 0.033) than those patients without DE. Patients with DE also had significantly thicker and more severe atheroma and a tendency toward more prominent inflammation and vascularity in pathologic findings. There was no significant difference in wall thickness between AAA with and without DE (1.44 +/- 0.7 versus 1.24 +/- 0.22 mm, P = 0.352). Delayed enhancement on CT demonstrated in over half of atherosclerotic AAA may be associated with chronic inflammation by atherosclerosis.

Matrix metalloproteinase 2 is suppressed by trapidil, a CD40-CD40 ligand pathway inhibitor, in human abdominal aortic aneurysm wall.

BACKGROUND: The activation of inflammatory cells and the production of matrix metalloproteinases (MMPs) are important in the pathogenesis of abdominal aortic aneurysm (AAA). Previous studies have demonstrated that the antiplatelet agent trapidil has multiple actions, including suppression of MMP expression through the inhibition of the CD40-CD40 ligand (CD40-CD40L) pathway in cultured cells. A recent clinical study suggested that trapidil might have functions beyond its antiplatelet action. Methods and results In the present study, we performed immunohistochemical analysis and semiquantitative reverse transcription-polymerase chain reaction to evaluate the effect of trapidil on the production of MMPs in cultured aortic tissues from patients with infrarenal AAA (n = 9) and control patients with aortoiliac occlusive disease (n = 7). The tissue concentrations of both MMP-2 and MMP-9 were significantly higher in AAA walls than in control aortic walls. Both trapidil and an anti-CD154 (CD40L) antibody significantly suppressed the protein production and mRNA expression of MMP-2 but did not inhibit those of MMP-9 in organ cultures of AAA wall specimens. MMP-9 was produced by macrophages and a lot of neutrophils in AAA tissues, whereas MMP-2 was derived from macrophages. CD40 was expressed on macrophages but not on neutrophils, and this expression could explain the differential effect of trapidil on the production of MMP-2 and MMP-9. CONCLUSIONS: Trapidil, a CD40-CD40L pathway inhibitor, suppressed mRNA expression and protein production of MMP-2 in AAA tissues, suggesting a potential therapeutic approach for the prevention or treatment of AAA.

Expression of peroxisome proliferator-activated receptor-gamma in vascular smooth muscle cells is upregulated in cystic medial degeneration of annuloaortic ectasia in Marfan syndrome.

BACKGROUND: Cystic medial degeneration (CMD) is a histological abnormality that is common in annuloaortic ectasia (AAE) and aortic dissection with Marfan syndrome. Apoptosis and loss of vascular smooth muscle cells (VSMCs) is one of the features of CMD, but little is known about its pathogenesis. Peroxisome proliferator-activated receptor-gamma (PPARgamma), a transcription factor of the nuclear receptor superfamily, has been reported to show antiproliferative effects on VSMCs as well as anti-inflammatory effects on macrophages. PPARgamma agonist has been recently reported to induce apoptosis of cultured VSMCs. METHODS: We examined the histopathology of ascending aortas in AAE of Marfan patients (n=21) and control patients (n=6) at surgery. RT-PCR was performed to demonstrate expression of PPARgamma in CMD. Localization of PPARgamma was determined by double immunostaining using antibodies against PPARgamma and cell-specific markers (ie, SMCs, macrophages, and T lymphocytes). RESULTS: PPARgamma expression was upregulated in AAE samples but minimal in control samples by RT-PCR (P=0.07). Immunoreactivity against PPARgamma in numerous nuclei of VSMCs was observed in CMD lesions. Severity of CMD correlated with positive immunoreactivity of PPARgamma in medial VSMCs (P=0.03). No inflammatory cells (ie, macrophages or T lymphocytes) were detected in CMD lesions. CONCLUSION: PPARgamma expression is upregulated in SMCs of CMD without any inflammatory response. Activated PPARgamma in VSMCs might be involved in the pathogenesis of CMD in Marfan's aortas. Regulation of PPARgamma might lead to clinical implication in protection against progression of AAE.

An angiotensin-converting enzyme inhibitor, not an angiotensin II type-1 receptor blocker, prevents beta-aminopropionitrile monofumarate-induced aortic dissection in rats.

OBJECTIVE: Cystic medial degeneration (CMD) is a histologic abnormality that is common in aortic diseases such as aortic dilation, aneurysm, or dissection. Although little is known about the mechanism underlying CMD, we have previously demonstrated that angiotensin II signaling via angiotensin II type 2 receptor (AT2R) plays a central role in apoptosis of vascular smooth muscle cells (VSMCs) occurring in CMD associated with Marfan syndrome. The aim of this study is to elucidate the role of angiotensin II signaling in THE pathogenesis of aortic diseases associated with CMD. METHOD: We investigated the effects of angiotensin-converting enzyme inhibitor (ACEI), temocapril (n = 15), angiotensin II receptor type-1 (AT1R) blocker, CS-866 (n = 15), and vehicle control (n = 17) on 0.25% beta-aminopropionitrile monofumarate (BAPN)-induced aortic dissection and histopathologic findings in a rat model. RESULTS: Temocapril significantly prevented aortic dissection (P <.05), CMD (P <.01), and VSMC apoptosis (P <.01) compared with vehicle control in BAPN-fed rats. However, CS-866 did not show any preventive effect. Reversed transcriptase-polymerase chain reaction demonstrated that expression of both AT1R and AT2R was detected in control rat aortas, and that AT2R expression was significantly upregulated in the aortas of BAPN-fed rats (P <.01). Blood pressure was significantly and equally lowered in both temocapril and CS-866 groups compared with control. CONCLUSIONS: Differential expression of angiotensin II receptors and AT2R signaling are involved in the pathogenesis of CMD and aortic dissection in BAPN-fed rats. ACEIs might be of clinical value for the prevention and treatment of aortic diseases related to CMD.

A 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, cerivastatin, suppresses production of matrix metalloproteinase-9 in human abdominal aortic aneurysm wall.

AIM: Abdominal aortic aneurysm (AAA) is a common vascular degenerative disease. AAA wall contains inflammatory cells that produce matrix metalloproteinases (MMPs) that probably contribute to elastolysis and remodeling of the aneurysm. 3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have been shown to reduce the expression of various molecules (including MMPs) independently of their cholesterol-lowering effect. The aims of this study are to investigate whether statins could modulate the biology of AAA wall and have a potential therapeutic value against AAAs. METHODS: We performed immunohistochemical analysis, evaluated MMP-9 production in the aortic wall from patients with infrarenal AAA (n = 10) and control patients with aortoiliac occlusive disease (n = 8), and examined the effect of cerivastatin on MMP-9 production in the AAA wall with organ culture. RESULTS: Neutrophils and macrophages were the cellular sources of MMP-9 in the AAA wall. The tissue concentrations of both total and active MMP-9 were significantly higher in tissues from AAA walls than in control aortic walls. Cerivastatin (0.001 to 0.1 micromol/L) significantly reduced the tissue levels of both total and active MMP-9 in a concentration-dependent manner (P <.001), and the production of tissue inhibitor of MMP-1 was unaffected. Cerivastatin neither reduced the number of infiltrating neutrophils and macrophages nor enhanced apoptosis of those cells, as evaluated with terminal transferase-mediated deoxyurisine triphosphate nick end labeling. CONCLUSION: These results suggest that cerivastatin can directly modulate the biology of the AAA wall and suppress MMP-9 production in the AAA wall by inhibiting the activation of neutrophils and macrophages, indicating that statin therapy could be useful for the prevention or treatment of AAA.