Tympanosclerosis and atherosclerosis plaques: a comparative analytical study on some new microbiological and immunohistochemical aspects.

Purpose: The aim of this study was to compare chemical contents, expression of BMP-8a, and the presence of Mycoplasma and ExoS-ExoU exotoxins producing Pseudomonas aeruginosa in tympanosclerosis (TS) and atherosclerosis (AS) plaques.

Methods: Thirty-six cases with TS and AS plaques (18 each) were selected and examined for chemical, immunohistochemical, and microbial analysis. SPSS ver. 21 and t test analysis were used for comparing the findings, and the level of significance was considered as p < 0.05.

Results: TS plaques showed lower carbon, higher calcium, and phosphorous contents compared to AS plaques (p value < 0.05). Chlorine was detected in AS plaques (1.8 w%) which could probably be due to the presence of myeloperoxidase (MPO) in atherosclerotic artery. Contrary to spherical shape of the surface of TS plaques, AS plaques were needle shaped. BMP-8a expression in TS plaques (59.5%) was significantly higher (p value < 0.0001) than AS plaques (20%). Of the 18 TS specimens, 12, 14, and 3 were positive for ExoS, ExoU Pseudomonas aeruginosa, and Mycoplasma genes, respectively, while of the 18 AS specimens, 2, 2, and 3 were positive for ExoS, ExoU Pseudomonas aeruginosa, and Mycoplasma genes, respectively.

Conclusion: TS plaques are different from AS plaques in terms of elemental components, surface morphology, and BMP-8a expression. Therefore, different calcification process and pathogenesis may be responsible for these two diseases. The results of our study showed that both TS and AS plaques have genetic footprint of Mycoplasma, but the level of calcium concentration-dependent exotoxins genes was found only in TS plaques.