Bacterial DNA in Calcified Aortic Valve Tissue Using Targeted qPCR
Max Sundström
Calcific aortic valve disease is characterized by progressive fibrosis and calcification of the valve, but the factors contributing to its development are not fully understood. Previous studies have identified bacterial material, including DNA from oral-associated microorganisms, in diseased cardiovascular tissues. To investigate bacterial DNA in calcified aortic valve tissue, DNA was extracted from samples collected during aortic valve replacement surgery and analysed using targeted quantitative PCR assays for selected bacterial taxa. Bacterial DNA was detected across several targets, with substantial variation in detection frequency. Fusobacterium nucleatum was detected most frequently in 120 of 162 samples (74.1%), followed by Veillonella parvula in 77 samples (47.5%) and Staphylococcus epidermidis in 76 samples (46.9%). Clostridium leptum was detected in 41 samples (25.3%), while viridans group streptococci and Enterobacter spp. were detected in 39 (24.1%) and 38 samples (23.5%) respectively. Atypical amplification signals were manually reviewed, and selected qPCR products were further assessed using TapeStation electrophoresis. Total extracted DNA concentration showed no strong apparent relationship with bacterial qPCR signal. Previously prepared immunohistochemical material from the same surgical sample series was also reviewed as complementary histological material, showing immunoreactivity for Veillonella spp. and viridans group streptococci in calcified aortic valve tissue. Bacterial target DNA was detected across several bacterial taxa in the analysed calcified aortic valve samples.
Supervisors: Pekka Karhunen (TUNI), Kirsikka Musta (TUNI), and Janne Ihalainen (JYU)
