Abdominal aortic aneurysm (AAA) is characterized by chronic aortic wall inflammation and loss of matrix components. Proinflammatory cytokines such as tumour necrosis factor-alpha (TNF-alpha) are thought to be involved in this inflammatory process and, therefore, to play an important role in the pathogenesis of human AAA. TNF-alpha-converting enzyme (TACE) has recently been purified and cloned as a disintegrin and metalloproteinase that converts TNF-alpha precursor into its mature form. The aim of the present study was to determine whether TNF-alpha and TACE were expressed and localized in aortic tissues in human AAA. Infrarenal aortic tissues were obtained from AAA patients (n=19) undergoing elective aneurysm reconstruction and from autopsy cases without cardiovascular disorders as normal controls (n=5). Internal thoracic artery samples were also obtained from patients with coronary artery disease undergoing coronary artery bypass grafting to represent biopsied conduit vessels (n=5). The AAA specimens were taken from the mid-portion of the aneurysm and from the longitudinal transition zone between the non-dilated aorta and the proximal aspect of the aneurysm. TNF-alpha and TACE mRNA levels were determined by real-time quantitative reverse transcriptase-PCR. Expression levels of both TNF-alpha mRNA and TACE mRNA were significantly greater in the transition zone than in the mid-portion (both P<0.05). Expression levels of both forms of mRNA were significantly higher in AAA samples than in control aortas or atherosclerotic arteries. There was a significant correlation between the expression of TNF-alpha mRNA with that of TACE mRNA in AAA (r=0.54, P<0.005). Immunostaining was positive for both TNF-alpha and TACE in CD68-positive macrophages in the media and adventitia obtained from the transition zone in AAA, whereas neither TNF-alpha nor TACE was expressed in control vessels. In conclusion, the concomitant activation and localization of TNF-alpha and TACE in the media and adventitia of the transition zone in human AAA underlines the importance of this system in the pathogenesis of this disorder.

This study has shown that increased myocardial TACE expression is associated with elevated myocardial TNF-alpha expression in both mRNA and protein levels in clinically advanced DCM.

These findings indicate that the expression of TNF-alpha and TACE may have important implications in the pathogenesis of myocarditis and may influence advanced cardiac dysfunction in myocarditis.

The pathway of tissue aldosterone production may exist in the heart, and may be an important contributory factor to myocardial fibrosis and cardiac remodelling in the failing heart. CYP11B2 (aldosterone synthase) catalyses the final step of aldosterone production. The aim of the present study was to determine whether CYP11B2 and CYP11B1 (11beta-hydroxylase) are expressed in myocardial tissues, and whether these enzymes contribute to collagen accumulation and myocardial dysfunction in the failing human heart. Endomyocardial tissues were obtained from 23 patients with chronic heart failure (CHF) and 10 controls. CYP11B2 and CYP11B1 mRNA levels were measured by real-time quantitative reverse transcriptase-PCR. The myocardial collagen volume fraction (CVF) was determined by digital planimetry. CYP11B2 mRNA expression was greater in the CHF group than in the controls (P<0.05), while CYP11B1 mRNA was barely expressed in either group. There was a positive correlation between CYP11B2 mRNA levels and CVF (r=0.64, P=0.001). CYP11B2 mRNA was particularly highly expressed in subgroups of CHF patients with a large left ventricular end-systolic diameter (>55 mm) or a low left ventricular ejection fraction (<30%). CYP11B2 mRNA expression and CVF were lower in a CHF subgroup treated with a combination of spironolactone and angiotensin-converting enzyme inhibitors (ACEIs) than in a subgroup not treated with these drugs. In conclusion, this study has shown that increased myocardial expression of CYP11B2 mRNA is associated with increased myocardial fibrosis and with the severity of left ventricular dysfunction in human CHF. In addition, CYP11B2 expression and cardiac fibrosis are found to be decreased in CHF patients on drug therapy comprising spironolactone combined with ACEIs.

No abstract