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Matrix metalloproteinase-9 expression is associated with the presence of Chlamydia pneumoniae in human coronary atherosclerotic plaques
  1. G Arno,
  2. J C Kaski,
  3. D A Smith,
  4. J P Akiyu,
  5. S E Hughes,
  6. C Baboonian
  1. Department of Cardiological Sciences, St Georges Hospital Medical School, London, UK
  1. Correspondence to:
    Gavin Arno
    Department of Cardiological Sciences, St Georges Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK;


Objective: To investigate the association between Chlamydia pneumoniae and matrix metalloproteinase-9 (MMP-9) in atherosclerotic plaques.

Design: 31 coronary atherosclerotic plaque specimens were studied by immunohistochemistry, polymerase chain reaction (PCR), and reverse transcription PCR for the presence of C pneumoniae antigen and genomic DNA, and of MMP-9 protein and transcripts.

Results: Immunohistochemical analysis identified a strong association between the presence of C pneumoniae antigen and production of MMP-9 in coronary atherosclerotic plaques (p  =  0.001). Furthermore, analysis of the intralesional amount of C pneumoniae and MMP-9 indicated an increased number of cells positive for MMP-9 in arterial sections that had increased C pneumoniae positivity (p < 0.05).

Conclusions: This study provides evidence of an association between expression of MMP-9 and the intravascular presence of C pneumoniae and may suggest a potential pathological mechanism whereby C pneumoniae may contribute to the progression of coronary atherosclerosis.

  • MMP, matrix metalloproteinase
  • PCR, polymerase chain reaction
  • RT-PCR, reverse transcription polymerase chain reaction
  • atherosclerosis
  • Chlamydia pneumoniae
  • immunohistochemistry
  • matrix metalloproteinase
  • polymerase chain reaction

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