In vitro degradation of aortic elastin by Chlamydia pneumoniae

Quantification and location of Chlamydia pneumoniae-specific antigen in the walls of abdominal aortic aneurysms

BACKGROUND

To evaluate the prevalence and quantity of Chlamydia pneumoniae-specific antigen in the three layers (intima, media, and adventitia) of abdominal aortic aneurysms (AAAs), so as to further investigate the pathogenesis of AAAs.

METHODS

Aortic walls were collected from 20 patients with AAA and 11 healthy organ donors. Immunohistochemistry was used to identify the C pneumoniae-specific antigen, and image analysis system was used to quantify and locate it.

RESULTS

The positive rate of C pneumoniae-specific antigen was higher in the AAA group than in the control group (100% vs. 54.54%, p = 0.003), positive intensity decreased from the tunica intima to the adventitia in the AAA group (16.32% ± 2.13%, 14.84% ± 1.80%, and 14.25% ± 1.67%, respectively, p = 0.003). In the control group, positive cells were mainly found in focal lesion areas.

CONCLUSION

We have demonstrated the presence and differentiation of C pneumoniae-specific antigen in the three layers of AAAs, which are in accordance with pathology, thus suggesting a pathogenic role of the antigen.

Persistent Chlamydophila pneumoniae infection in thoracic aortic aneurysm and aortic dissection?

OBJECTIVES

Chlamydophila pneumoniae (C. pneumoniae) has been associated with atherosclerosis and abdominal aortic aneurysm and is probably disseminated by peripheral blood mononuclear cells (PBMC). Viable and metabolically active bacteria can be demonstrated by the presence of bacterial mRNA and on-going dissemination by the presence of bacteria in PBMC. The aim of this study was to determine the prevalence of C. pneumoniae DNA and mRNA in aortic biopsies and C. pneumoniae DNA in PBMC in thoracic aortic aneurysm and aortic dissection patients.

DESIGN

Real-time PCR was used to detect C. pneumoniae DNA and mRNA in biopsies and C. pneumoniae DNA in PBMC.

RESULTS

C. pneumoniae DNA was found in biopsies in 26% (6/23) of aneurysm patients and 11% (2/18) of dissection patients but in none of the forensic autopsy controls. C. pneumoniae mRNA was not found in any biopsy, and all PBMC were C. pneumoniae-negative.

CONCLUSIONS

Presence of C. pneumoniae DNA but not mRNA in aortic biopsies and no evidence of C. pneumoniae in PBMC suggest that the infection in the aorta has passed into a state of persistence.

Chlamydia pneumoniae in patients undergoing surgery for thoracic aortic disease

OBJECTIVE

To investigate if Chlamydia pneumoniae is present in the wall of the thoracic aorta in patients operated on for aneurysm or aortic dissection.

DESIGN

Consecutive patients undergoing surgery for thoracic aortic aneurysm (TAA, 32 patients) and for aortic dissection (6 patients) were included in this prospective study. Tissue samples from the aorta were analysed for the presence of C. pneumoniae by polymerase chain reaction (PCR), histopathology, immunohistochemistry and in one aortic tissue sample C. pneumoniae was verified by electron microscopy and immunogold labelling technique. Cultured Hep 2 cells infected with C. pneumoniae were used as a positive control for electron microscopy. Sera for microimmunofluorescence were obtained in 36/38 and throat swabs for C. pneumoniae PCR in 17/38 patients.

RESULTS

Chlamydia pneumoniae was detected by PCR in 4 of 32 TAA tissue samples (12%) and in 0 of 6 patients operated on for aortic dissection. Chlamydia pneumoniae inclusion bodies in one of the PCR positive tissue samples were verified by electron microscopy. IgG antibodies to C. pneumoniae were present in 17/31 (55%) and IgA in 15/31 (48%) of the TAA patients and in none of five tested patients with dissection. None of the tested throat swabs was positive.

CONCLUSION

In this study we report the presence of C. pneumoniae by PCR and electron microscopy in the wall of TAA. A high prevalence of serum IgA antibodies to C. pneumoniae was found in TAA patients. In contrast no signs of C. pneumoniae were detected in patients with thoracic aortic dissection.

Serum concentrations of elastin-derived peptides in patients with specific manifestations of atherosclerotic disease

OBJECTIVE

To measure serum concentrations of elastin-derived peptides (S-EDP) in patients with aneurysmal, occlusive and ulcerative manifestations of atherosclerotic disease.

MATERIALS AND METHODS

S-EDP concentrations were measured by a competitive enzyme-linked immunosorbent assay in 10 patients with infrarenal aneurysms 5cm in diameter (AAA), 10 patients with distal aortic occlusive disease (AOD), 10 patients with symptomatic carotid stenosis (>or=70%) and plaque ulceration (SCS) and a control group of 10 patients with no similar specific manifestations of atherosclerotic disease (NAM).

RESULTS

S-EDP concentrations (median, range) were significantly higher in patients with AAA (42ng/ml, 35-52, p<0.001) and SCS (49ng/ml, 37-60, p<0.001) but not AOD (28ng/ml, 22-38, p=0.240) compared to NAM (26ng/ml, 19-36) patients.

CONCLUSION

Increased concentrations of S-EDP were associated with aneurysmal and ulcerative, but not occlusive, manifestations of atherosclerosis.

Presence of Chlamydia pneumoniae in abdominal aortic aneurysms is not associated with increased activity of matrix metalloproteinases

OBJECTIVE

to test the hypothesis that the presence of Chlamydia pneumoniae (C. pneumoniae) in the wall of abdominal aortic aneurysms (AAA) is associated with increased activity of matrix metalloproteinase (MMP)-2 and/or MMP-9.

DESIGN

case-control study.

MATERIAL AND METHODS

in a series of 40 patients with AAA > or =5cm in maximal cross-sectional diameter, C. pneumoniae-DNA was identified in the aneurysm wall by nested PCR in 14 (35%) patients. Another 14 C. pneumoniae-DNA-negative AAA patients from the same series, matched for gender and aneurysm diameter, were used as controls. In each group there were 7 asymptomatic (aAAA) and 7 ruptured (rAAA) aneurysms. MMP-2 and -9 activity was estimated in AAA wall biopsies by gelatin zymography.

RESULTS

patients with a C. pneumoniae-DNA-positive aneurysm wall specimen showed an over-all lower activity of MMP-2 and MMP-9 (pro- and active enzyme) compared to the C. pneumoniae-DNA negative patients. However, there were no statistically significant differences in MMP activity between the two groups of patients with aAAA. Among patients with rAAA both pro-MMP-9 (p=0,026) and active-MMP-9 (p=0.007) were significantly lower in C. pneumoniae-DNA-positive patients compared to C. pneumoniae-DNA-negative patients, whereas there were no significant differences in pro-MMP-2 or active-MMP-2.

CONCLUSION

this preliminary study does not support the hypothesis that the presence of C. pneumoniae in the AAA wall is associated with increased activity of MMP-2 and MMP-9.