[Chlamydia pneumoniae and cytomegalovirus in degenerative aortic valve stenoses]

Recent evidence suggests a causal relationship between inflammatory as well as infectious pathomechanisms and valvular degeneration. Based on the concept of chronic Chlamydia pneumoniae and cytomegalovirus (CMV) infections, and of variable stressors working on valvular microecology, the present study sought to assess the presence of the specific chlamydial heat shock protein (cHSP) 60, of CMV, of macrophages and of the human homologue hHSP60. Serial sections of high-grade degenerated native (n = 16) and prosthetic (n = 6) aortic valves were analyzed by immunohistochemistry for the presence of these determinants. Degenerated aortic valves revealed prevalence of Chlamydia pneumoniae in 41% (10 of 22) and CMV in 73% (16 of 22), while immunoreactive hHSP60 was present in 64% (14 of 22) and CD68 in 86% (19 of 22). Chlamydial HSP60, CMV and hHSP60 were predominantly found in valvular fibrosa; CMV showed a second predilection site at the ventricular luminal border. Both microorganisms revealed a strong correlation between each other (r = 0.73; p < 0.001) as well as with hHSP60 (cHSP60: r = 0.74; p < 0.001; CMV: r = 0.80; p < 0.001). Macrophage infiltration correlated with cHSP60 (r = 0.78; r < 0.001), CMV (r = 0.78; r < 0.001) and hHSP60 (r = 0.56; r = 0.007). Of note, the frequency of cHSP60, CMV and CD68 signaling was increased more than 5-fold in prosthetic valves compared to native valves (p = 0.017, p = 0.002 and p = 0.005). In summary, valvular infections of Chlamydia pneumoniae and of cytomegalovirus are frequently seen in degenerated aortic valves, irrespective of native or prosthetic origin. Colocalization of both HSP60 homologues and cytomegalovirus within macrophages in valvular fibrosa points to regional stressor effects that might be at least partly attributable to chronic persistent pathogen burden and molecular mimicry.