Density of Chlamydia pneumoniae is increased in fibrotic and calcified areas of degenerative aortic stenosis

Background The process of aortic degeneration associated with calcified aortic stenosis shares many similarities with coronary artery atherosclerosis. Inflammation and infection are involved in both diseases. Chlamydia pneumoniae has been identified in atherosclerotic plaques. However, the studies about the presence of C. pneumoniae in degenerative aortic stenotic valves are not conclusive. Objective We investigated whether an association exists between the density of C. pneumoniae and fibrosis or calcification in aortic stenosis. Design Autopsy and surgical specimens were divided into 3 groups: Normal, 11 normal autopsy valves Atherosclerosis, 10 autopsy valves from patients with systemic atherosclerosis and no aortic stenosis and Aortic stenosis, 14 surgical specimens of aortic valves replaced due to aortic stenosis. Setting Heart Institute (InCor), University of São Paulo Medical School. Patients Aortic valves from patients aged 52 ± 16 years, 69 ± 9 years, and 71 ± 8 years. Invention Specimens were evaluated by immunohistochemical technique (to detect C. pneumoniae antigens), in situ hybridization, and electron microscopy (to quantify the density of C. pneumoniae in the valves). Measurements The aortic stenosis group was analyzed according to 3 subregions: aortic stenosis-preserved, peripheral preserved regions; aortic stenosis-fibrosis, peri-calcified fibrotic tissue; and aortic stenosis-calcification, calcified nodules. Results The median values of C. pneumoniae antigens were 0.09, 0.30, 0.18, 1.33, and 3.3 in groups Normal, Atherosclerosis, Aortic stenosis-preserved, Aortic stenosis-fibrosis, and Aortic stenosis-calcification, respectively. The amount of C. pneumoniae was greater in the Atherosclerosis and Aortic stenosis-calcification groups than in the Normal group (P < 0.05). C. pneumoniae was greater in the Aortic stenosis group in the calcified and fibrotic regions than in preserved region (P < 0.05). Conclusion An association was found between the higher density of C. pneumoniae and fibrosis/calcification in stenotic aortic valves.