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Infectious agents is a risk factor for myxomatous mitral valve degeneration: A case control study

Marcos Gradim Tiveron¹, Pablo Maria Alberto Pomerantzeff², Maria de Lourdes Higuchi²

¹Program in Thoracic and Cardiovascular Surgery, Medical School, University of Sao Paulo, Av. Dr. Enéas de Carvalho Aguiar, 44, Sao Paulo, 05403-900, Sao Paulo, Brazil. mgtiveron@yahoo.com.br.

BMC Infectious Diseases

|April 23, 2017

Abstract

Background:

The etiology of myxomatous mitral valve degeneration (MVD) is not fully understood and may depend on time or environmental factors for which the interaction of infectious agents has not been documented. The purpose of the study is to analyze the effect of Mycoplasma pneumoniae (Mp), Chlamydophila pneumoniae (Cp) and Borrelia burgdorferi (Bb) on myxomatous mitral valve degeneration pathogenesis and establish whether increased in inflammation and collagen degradation in myxomatous mitral valve degeneration etiopathogenesis.

Methods:

An immunohistochemical test was performed to detect the inflammatory cells (CD20, CD45, CD68) and Mp, Bb and MMP9 antigens in two groups. The in situ hybridization was performed to detect Chlamydophila pneumoniae and the bacteria study was performed using transmission electron microscopy. Group 1 (n = 20), surgical specimen composed by myxomatous mitral valve degeneration, and group 2 (n = 20), autopsy specimen composed by normal mitral valve. The data were analyzed using SigmaStat version 20 (SPSS Inc., Chicago, IL, USA). The groups were compared using Student's t test, Mann-Whitney test. A correlation analysis was performed using Spearman's correlation test. P values lower than 0.05 were considered statistically significant.

Results:

By immunohistochemistry, there was a higher inflammatory cells/mm2 for CD20 and CD45 in group 1, and CD68 in group 2. Higher number of Mp and Cp antigens was observed in group 1 and more Bb antigens was detected in group 2. The group 1 exhibited a positive correlation between the Bb and MVD percentage, between CD45 and Mp, and between MMP9 with Mp. These correlations were not observed in the group 2. Electron microscopy revealed the presence of structures compatible with microorganisms that feature Borrelia and Mycoplasma characteristics.

Conclusions:

The presence of infectious agents, inflammatory cells and collagenases in mitral valves appear to contribute to the pathogenesis of MVD. Mycoplasma pneumoniae was strongly related with myxomatous mitral valve degeneration. Despite of low percentage of Borrelia burgdorferi in MD group, this agent was correlated with myxomatous degeneration and this may occour due synergistic actions between these infectious agents likely contribute to collagen degradation.

Insights

Infectious agents like Mycoplasma pneumoniae may contribute to myxomatous mitral valve degeneration (MVD). This study found a strong link between Mycoplasma pneumoniae and MVD, suggesting a role for infections in heart valve disease.

Area of Science:

Cardiovascular Pathology
Infectious Diseases
Molecular Biology

Background:

The exact causes of myxomatous mitral valve degeneration (MVD) remain unclear, with limited documentation on the role of infectious agents.
Investigating potential environmental or time-dependent factors is crucial for understanding MVD etiology.

Purpose of the Study:

To determine the impact of Mycoplasma pneumoniae (Mp), Chlamydophila pneumoniae (Cp), and Borrelia burgdorferi (Bb) on MVD pathogenesis.
To assess the role of inflammation and collagen degradation in MVD.

Main Methods:

Immunohistochemistry was used to detect inflammatory cells (CD20, CD45, CD68) and antigens (Mp, Bb, MMP9).
In situ hybridization identified Chlamydophila pneumoniae, and transmission electron microscopy examined bacterial structures.
Surgical MVD specimens (n=20) were compared with normal autopsy mitral valve specimens (n=20).

Main Results:

Group 1 (MVD) showed higher CD20 and CD45 inflammatory cells compared to Group 2 (normal).
Mp and Cp antigens were more prevalent in MVD valves, while Bb was more frequent in normal valves.
Positive correlations were found between Bb and MVD percentage, CD45 and Mp, and MMP9 and Mp in the MVD group.

Conclusions:

Infectious agents, inflammatory cells, and collagenases likely contribute to MVD pathogenesis.
Mycoplasma pneumoniae demonstrated a significant association with MVD.
Borrelia burgdorferi, despite lower prevalence, correlated with MVD, suggesting synergistic action with other agents in collagen degradation.

Read full analysis

Keywords:

Borrelia burgdorferi Chlamydophila pneumoniae Inflammatory markers Metalloproteinases Mitral valve Mycoplasma pneumoniae Myxomatous degeneration

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