Angiotensin-converting enzyme and chymase, two Ang II-forming enzymes, are locally expressed in aortic valves, and owing to infiltration of macrophages and MCs, are further upregulated in stenotic valves. These novel findings, implicating chronic inflammation and an increased expression of local Ang II-forming systems, suggest that therapeutic interventions aiming at inhibiting these processes may slow AS progression.

In isolated AS, increased LV mass predicts the presence of systolic dysfunction and HF independent of the severity of valvular obstruction. LV hypertrophy may be maladaptive rather than beneficial in AS in man.

In stenotic aortic valves, mast cell-derived cathepsin G may cause adverse valve remodelling and AS progression.

Sorsa T, Uitto V-J, Suomalainen K, Turto H and Lindy S: A trypsin-like protease from Bacteroides gingivalis: partial purification and characterization. J Periodont Res 1987; 22: 375-380. Extracts of cell sonicates of Bacteroides gingivalis were shown to contain proteolytic enzymes capable of degrading connective tissue proteins. In this study, neutral proteolytic enzymes, i.e. coilagenase and a trypsin-like protease, were isolated. The trypsin-like protease was readily separated from coliagenase by affinity chromatography on Benzamidine-Sepharose, Proteases were further purified by gel filtration on Sephacryl S-200; apparent molecular weights of 35 kDa and 70 kDa were obtained for a trypsin-like protease and coilagenase, respectively. Further characterization of the potent trypsin-like protease showed that the enzyme was inhibited by serine protease inhibitors phenylmethylsulfonyl fiuoride and benzamidine and by metalloprotease inhibitor EDTA, as well as ascorbic acid. Activation of the enzyme was observed with reducing agents and human serum. The trypsin-like protease was found to be capable of degrading native type IV collagen and denatured type I collagen but not native type I collagen. Thus, we conclude that in addition to coUagenase a potent trypsin-like protease from Bacteroides gingivalis may be involved in the etiopathogenesis of periodontal disease. Since the trypsin-like protease is able to degrade the basement membrane collagen (type IV) in the presence of human serum, this enzyme may be a potent virulence factor of Bacteroides gingivalis in relation to invasiveness and connective tissue destruction.

Objective-To investigate the possible role of elastolytic cathepsins S, K, and V and their endogenous inhibitor cystatin C in adverse extracellular matrix remodeling of stenotic aortic valves. Methods and Results-Stenotic aortic valves were collected at valve replacement surgery and control valves at cardiac transplantations. The expression of cathepsins S, K, and V and cystatin C was studied by conventional and real-time polymerase chain reaction and by immunohistochemistry. Total cathepsin activity in the aortic valves was quantified by a fluorometric microassay. When compared with control valves, stenotic valves showed increased mRNA expression of cathepsins S, K, and V (PϽ0.05 for each) and a higher total cathepsin activity (PϽ0.001). In stenotic valves, cystatin C mRNA was increased (PϽ0.05), and cystatin C protein was found particularly in areas with infiltrates of inflammatory cells. Both cathepsin S and cystatin C were present in bony areas of the valves, whereas cathepsin V localized to endothelial cells in areas rich of neovascularization. Incubation of thin sections of aortic valves with cathepsins S, K, and V resulted in severe disruption of elastin fibers, and this cathepsin effect could be blocked by adding cystatin C to the incubation system. Key Words: aortic stenosis Ⅲ cathepsin Ⅲ cystatin C Ⅲ elastin Ⅲ heart valves A ortic stenosis is an active inflammatory process resembling atherosclerosis. The pathophysiological changes in the stenotic aortic valves include inflammatory cell infiltration, neoangiogenesis, accumulation of lipids, and active mediators of calcification with extracellular matrix (ECM) degradation. 1-7 Furthermore, aortic valvular myofibroblasts undergo phenotypic changes toward an osteoblast-like phenotype, and active bone formation and remodeling occur in the stenotic valves. 8,9 These processes lead to loss of normal valvular geometry, disruption of the elastic fibers, and accumulation of fibrocalcific masses. This adverse remodeling of the valves is associated with the loss of their mechanical and elastic properties, leading to thickening and stiffening of the valve leaflets and to progression of aortic stenosis. Conclusions-StenoticThe pathophysiological mechanisms involved in the abnormal accumulation and degradation of ECM in the valves are incompletely understood. In atherosclerotic lesions, elastolytic cysteine proteases, including cathepsins S and K, are overexpressed at sites of arterial elastin damage, whereas their endogenous inhibitor, cystatin C, is severely reduced. 10,11 Moreover, a marked deficiency of cystatin C expression with accentuated cathepsin S and K expression in aortic aneurysms and a negative correlation of cystatin C serum levels with the diameter of abdominal aorta has been reported. 11 These observations support the role of an imbalance between cathepsins and cystatin C in diseases characterized by pathological elastin degradation. In addition, cathepsin K has a crucial role in bone matrix degradation necessary for normal bone growth and remodeling...

To investigate the effect of a fall of intrathoracic pressure on left ventricular (LV) hemodynamics and relaxation, simultaneous micromanometric recordings of LV and aortic pressures were performed at rest and during two graded Mueller maneuvers in 16 patients undergoing cardiac catheterization for aortic valve stenosis (n = 8) or chest pain (n = 8). The reductions (means +/- SE) of airway pressure during the lesser and greater maneuvers were 26 +/- 1 and 42 +/- 1 mmHg, respectively. Simultaneously, LV isovolumic-developed pressure increased by 9 +/- 3 and 21 +/- 4 mmHg, respectively (P < 0.03 for both). During the greater maneuver, the individual changes of the time constant of LV isovolumic relaxation (tau) correlated with the changes of LV isovolumic-developed pressure (r = 0.73; P = 0.002). In patients with a > 20-mmHg rise in isovolumic-developed pressure, tau increased by 10.3 +/- 4.6 ms. By multiple-regression analysis, the change of tau was related directly to the change of isovolumic-developed pressure (standardized coefficient beta = 0.80; P = 0.001) and inversely related to the resting systolic LV-aortic pressure gradient (beta = -0.37; P = 0.050). The other hemodynamic changes were independent of aortic valve stenosis. In conclusion, during the Mueller maneuver, the LV isovolumic contraction load increases and tau lengthens, particularly with higher elevations of LV systolic load.

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