Chlamydia pneumoniae in vascular tissues from heart-transplant donors

Chlamydia pneumoniae and multiple infections in the aorta contribute to atherosclerosis

Our previous study on herpesvirus infection including Herpes simplex virus type 1 (HSV-1), Epstein-Barr virus (EBV), cytomegalovirus (CMV) and atherosclerosis revealed that the prevalence of herpesvirus is higher in atherosclerotic aorta than in non-atherosclerotic aorta. Infections with two or three forms of the virus have been found only in atherosclerotic aorta. In our current study, we examined both Chlamydia pneumoniae and Chlamydia trachomatis in herpesvirus-infected aortic tissues, by means of immunohistochemistry, polymerase chain reaction, Southern hybridization, in situ hybridization, electron microscopy and electron-microscopic immunohistochemistry. In particular, the bacteria were found in atherosclerotic lesions. In atherosclerotic aorta, 40% of tissues examined were positive for C. pneumoniae in contrast to absence of this bacteria in non-atherosclerotic aorta. Elementary bodies of C. pneumoniae were found in macrophage-like cells in the intima of atherosclerotic aorta by electron microscopy. Chlamydia trachomatis was not found in both atherosclerotic and non-atherosclerotic aorta. Our findings suggest that multiple infections in aortic tissue contribute to the development of atherosclerosis. Furthermore, the absence of C. pneumoniae compared to herpesviruses in normal arterial tissue suggests that C. pneumoniae is specific for atherosclerotic lesions. In contrast to 'abortive infection' of viruses in arteries, C. pneumoniae infection was demonstrated in macrophages by electron microscopy and electron-microscopic immunohistochemistry in atherosclerotic lesion. Chlamydia pneumoniae may be the most important pathogen related to the development of atherosclerosis.

Chlamydia pneumoniae and hyperlipidemia are co-risk factors for atherosclerosis: infection prior to induction of hyperlipidemia does not accelerate development of atherosclerotic lesions in C57BL/6J mice

Chlamydia pneumoniae has been shown to accelerate atherosclerotic lesion development in hyperlipidemic animals. This study showed that C. pneumoniae did not accelerate lesion development in mice if a high-fat/high-cholesterol diet was started after infection, indicating that C. pneumoniae is a co-risk factor with hyperlipidemia for cardiovascular disease.

Randomized comparison of the type 4 phosphodiesterase inhibitor cipamfylline cream, cream vehicle and hydrocortisone 17-butyrate cream for the treatment of atopic dermatitis

BACKGROUND

Therapeutic options to treat atopic dermatitis are limited. Leukocytes from atopic patients have an abnormally high activity of cyclic adenosine monophosphate (AMP)-phosphodiesterase (PDE), which can be normalized in vitro by PDE inhibitors. Cipamfylline is a new potent and selective inhibitor of PDE-4.

OBJECTIVES

To compare the efficacy and safety of up to 14 days' topical treatment with cipamfylline (0.15%) cream with vehicle and with hydrocortisone 17-butyrate (0.1%) cream.

PATIENTS AND METHODS

International, multicentre, prospective, randomized double-blind, left-right studies of cipamfylline vs. vehicle and cipamfylline vs. hydrocortisone 17-butyrate in adult patients with stable symmetrical atopic dermatitis on the arms.

RESULTS

Both cipamfylline and hydrocortisone 17-butyrate reduced the Total Severity Score significantly (P < 0.001). The reduction with cipamfylline was significantly greater than that with vehicle (difference vehicle-cipamfylline 1.67 95% confidence interval (CI) 1.06, 2.28; P < 0.001) and was significantly less than with hydrocortisone 17-butyrate (difference hydrocortisone-cipamfylline -2.10 95% CI -2.93, -1.27; P < 0.001). Investigator and patient assessments of the overall treatment response showed a similar picture.

CONCLUSIONS

Cipamfylline cream is significantly more effective than vehicle, but significantly less effective than hydrocortisone 17-butyrate cream in the treatment of atopic dermatitis.

Correlation of chlamydia pneumoniae infection and severity of accelerated graft arteriosclerosis after cardiac transplantation

BACKGROUND

Chlamydia pneumoniae has been associated with atherosclerosis, although its role in the process is not clearly defined. Heart transplant recipients are known to have high titers of antibodies to C. pneumoniae, and the organism has been recovered from the coronary arteries of both transplant recipients and donors. This study evaluated association between C. pneumoniae infection and accelerated graft arteriosclerosis (AGA), also known as cardiac allograft vasculopathy (CAV), after cardiac transplantation.

METHODS

A case-control study was performed with 54 heart transplant recipients at the Johns Hopkins Hospital. Severe cases had >50% luminal narrowing on cardiac catheterization, mild cases <50% narrowing, and controls were free of arteriosclerotic disease. Blood specimens were examined for C. pneumoniae serology and DNA detection by polymerase chain reaction (PCR) assays.

RESULTS

For every twofold increase in geometric mean C. pneumoniae immunoglobulin (Ig)G titer, the odds ratio for severe AGA versus controls was 3.13 (P=0.03) and for mild AGA versus control patients was 1.61 (P=0.45). On Kaplan-Meier survival analysis there was a nonsignificant trend toward faster development of CAV in patients with higher C. pneumoniae antibody titers. Overall, 29% of heart transplant patients evaluated had evidence of circulating C. pneumoniae DNA by PCR, without a statistical difference between groups.

CONCLUSIONS

C. pneumoniae IgG titer correlates with severity of allograft arteriosclerosis after cardiac transplantation. Circulating C. pneumoniae DNA is detectable by PCR in up to 30% of cardiac transplant recipients, but this does not correlate with severity of allograft vasculopathy.

Chlamydia pneumoniae and atherosclerosis: critical assessment of diagnostic methods and relevance to treatment studies

A number of studies have found that inflammation of the vessel wall plays an essential role in both the initiation and progression of atherosclerosis and erosion and fissure and the eventual rupture of plaques. Chlamydia pneumoniae is one of the infectious agents that have been investigated as possible causes of this inflammation. Initial studies of the association of C. pneumoniae and cardiovascular disease (CVD) were seroepidemiologic, and these were followed by studies in which the organism was identified in vascular tissue from patients with CVD by electron microscopy, PCR and immunocytochemical staining (ICC). C. pneumoniae has also been isolated by culture from vascular tissue in a small number patients. However, no single serologic, PCR, or ICC assay has been used consistently across all studies. The assays used are also not standardized. Recent studies of serologic and PCR assays for diagnosis of C. pneumoniae infection have suggested that there may be substantial interlaboratory variation in the performance of these tests. It now appears that some of the inconsistency of results from study to study may be due, in part, to lack of standardized methods. Although initial seroepidemiologic studies demonstrated a significantly increased risk of adverse cardiac outcome in patients who were seropositive, subsequent prospective studies found either small or no increased risk. In addition to the lack of consistent serologic criteria, recent evaluations have demonstrated inherent problems with performance of the most widely used serologic methods. Most importantly, we do not have a reliable serologic marker for chronic or persistent C. pneumoniae infection.

Chlamydia pneumoniae in atherosclerotic tissue

The majority of almost 30 publications from 1992 to 1999 describe Chlamydia pneumoniae organisms in atherosclerotic lesions of various major arteries. In the first study in the United Kingdom, C. pneumoniae was found in the aorta and femoral and iliac arteries. In a subsequent study, the organism was detected in arteries of subjects as young as 15 years. In a collaborative investigation, 71% of atheromatous arteries taken at autopsy from white South African subjects were C. pneumoniae positive compared with 9% of nonatheromatous arteries. Of interest, the organisms were detected in 67% of vessels that showed only early atherosclerotic lesions (fatty streaks). C. pneumoniae was also found in the ruptured coronary artery plaque of a black South African who died of myocardial infarction, a rare event. The presence of C. pneumoniae organisms within foam and smooth muscle cells of atherosclerotic plaques is beyond doubt, but their role in atherosclerosis remains enigmatic.

Mouse models of C. pneumoniae infection and atherosclerosis

Mouse models were used to determine whether Chlamydia pneumoniae establishes chronic infection of the aorta and contributes to atherogenesis. Persistent infection of the aorta occurred in 11 of 31 hyperlipidemic apolipoprotein E-deficient (apoE(-/-)) mice but not in C57BL/6J mice fed a normal diet after a single inoculation and in both models following repeated inoculation with C. pneumoniae. Repeated inoculation of C57BL/6J mice resulted in inflammatory changes in the heart and aorta in 8 of 40 of mice; however, no atherosclerotic lesion development was observed. Repeated inoculation of apoE(-/-) mice resulted in a statistically significant increase in lesion area (n=43; P=.05). Although Chlamydia trachomatis disseminated to the aorta, persistent infection was not established and no statistically significant increase in lesion area occurred. These studies suggest that persistent infection of the aorta can lead to inflammatory changes in the absence of hyperlipidemia and accelerate lesion progress in concert with hyperlipidemia.

Detection of Chlamydia pneumoniae in arterial tissues

In literature in which detection of Chlamydia pneumoniae in the artery is described, the methods used were immunocytochemistry (ICC), polymerase chain reaction (PCR), electron microscopy, and isolation. These studies demonstrated the presence of the organism in atheromatous lesions. The organism was detected frequently by ICC and PCR in atheromatous tissues (approximately 50% of subjects) but rarely in normal arteries (approximately 1% of subjects). There has been poor correlation between detection and serology. Detection studies have been used to assess the etiologic role of C. pneumoniae in atherosclerosis and to determine whether C. pneumoniae infection contributes to acute cardiovascular events. Although these studies produced suggestive evidence of an etiologic role, the use of observational studies to obtain a definitive answer is difficult. Therefore, investigators are increasingly concentrating their efforts on studies that use animal models, in vitro cultured arterial cells, and therapeutic trials in humans to determine the pathogenic role of the organism in atherosclerosis.

Detection of Chlamydia pneumoniae DNA and antigen in the circulating mononuclear cell fractions of humans and koalas

Chlamydia pneumoniae is a common respiratory pathogen of humans which, in addition to causing disease at the respiratory site, has recently been linked to disease at other body sites. If C. pneumoniae does contribute to disease at nonrespiratory sites, then it must have a mechanism by which it reaches these sites. We analyzed the peripheral blood mononuclear cell (PBMC) fractions from 60 healthy human blood donors for the presence of C. pneumoniae DNA (by ompA PCR) and chlamydial antigens (by genus- and species-specific monoclonal antibody staining). Ten of the sixty (16. 7%) blood donors were C. pneumoniae positive by PCR, and all 10 of these PCR-positive individuals' samples demonstrated specific staining with anti-C. pneumoniae monoclonal antibodies. The only other host naturally infected with C. pneumoniae is the koala, in which the bacterium also causes respiratory infections. We demonstrated the presence of C. pneumoniae DNA and antigens in the PBMC fractions of 30% of 20 koalas tested. Our finding of C. pneumoniae-infected PBMCs in koalas as well as humans suggests that the ability to infect PBMCs and to disseminate from the respiratory site is not restricted to the human biovar of C. pneumoniae but is a general characteristic of this chlamydial species.

Protective DNA immunization against Chlamydia pneumoniae

We have investigated the efficacy of the DNA vaccination using the heat shock protein 60 (HSP-60) gene of C. pneumoniae, for protection of mice against infection with the bacteria. C57Bl/6 mice had a 5-20-fold reduction of C. pneumoniae numbers in lungs when immunized intranasally (i.n.) with plasmids (p) encoding pHSP-60. The reduction of the bacterial load coincided with a decreased severity of disease. No specific antibodies were detected after protective i. n. immunization. In contrast, mice immunized intradermally (i.d.) were not protected against challenge with C. pneumoniae, although specific humoral Immunoglobulin (Ig)G responses were generated. Co-inoculation i.n. of pHSP-60 with pIL-12 but not with pGM-CSF further increased protection of mice against infection with C. pneumoniae. Lungs from pHSP-60 i.n. immunized and infected mice showed higher levels of interferon (IFN)-gamma mRNA, and spleen cells from these mice co-cultured with r-HSP-60 released higher levels of IFN-gamma and displayed higher proliferative responses than nonimmunized and infected controls. pHSP-60 immunized IFN-gamma receptor (R)-/- mice were not protected against infection with C. pneumoniae. Likewise, i.n. administration of pIFN-gamma alone induced significant protection. DNA vaccine-induced protection was CD4+ and CD8+ T-cell dependent, as shown by DNA-vaccination of MHC class II-/-, CD4-/-, CD8-/- and CD4-/-CD8-/-mice. Interestingly, DNA vaccine induced CD4+ T cells, in the absence of CD8+ T cells, were involved in worsening the outcome of infection. This worsening was linked with a shift towards a Th2 cytokine pattern.

Chlamydia pneumoniae and atherosclerosis

OBJECTIVE

To review the literature for evidence that chronic infection with Chlamydia pneumoniae is associated with atherosclerosis and acute coronary syndromes.

DATA SOURCES

MEDLINE and Institute of Science and Information bibliographic databases were searched at the end of September 1998. Indexing terms used were chlamydi*, heart, coronary, and atherosclerosis. Serological and pathological studies published as papers in any language since 1988 or abstracts since 1997 were selected.

DATA EXTRACTION

It was assumed that chronic C pneumoniae infection is characterised by the presence of both specific IgG and IgA, and serological studies were examined for associations that fulfilled these criteria. Pathological studies were also reviewed for evidence that the presence of C pneumoniae in diseased vessels is associated with the severity and extent of atherosclerosis.

DATA SYNTHESIS

The majority of serological studies have shown an association between C pneumoniae and atherosclerosis. However, the number of cases in studies that have reported a positive association when using strict criteria for chronic infection is similar to the number of cases in studies which found no association. Nevertheless, the organism is widely found in atherosclerotic vessels, although it may not be at all diseased sites and is not confined to the most severe lesions. Rabbit models and preliminary antibiotic trials suggest that the organism might exacerbate atherosclerosis.

CONCLUSION

More evidence is required before C pneumoniae can be accepted as playing a role in atherosclerosis. Although use of antibiotics in routine practice is not justified, large scale trials in progress will help to elucidate the role of C pneumoniae.

The prevalence of Chlamydia pneumoniae in atherosclerotic and nonatherosclerotic blood vessels of patients attending for redo and first time coronary artery bypass graft surgery

OBJECTIVES

To determine if Chlamydia pneumoniae (C. pneumoniae) is more prevalent in atherosclerotic compared with normal blood vessels of patients requiring redo and first time coronary artery bypass graft surgery (CABG).

BACKGROUND

Serological and pathological studies have associated atherosclerosis with C. pneumoniae infection. As atherosclerosis is one of the causes of graft failure following CABG, then it may be expected that the prevalence of the organism in failed grafts and diseased native vessels should be greater than in the new grafts.

METHODS

Endarterectomy specimens and failed and new grafts were collected from 49 patients with late graft failure. Endarterectomy specimens and new grafts were also collected from nine patients having first time CABG. The presence of C. pneumoniae DNA was then checked for using a nested polymerase chain reaction.

RESULTS

The prevalence of C. pneumoniae DNA in failed venous grafts (38.2%) was similar to that in endarterectomy specimens from native coronary arteries (38.5%) and greater than that in new saphenous vein grafts (11.8%). However, it was similar to that in new internal mammary artery grafts (30.0%). Also, the interval between surgery in redo patients was the same regardless of whether C. pneumoniae was present or not.

CONCLUSIONS

Cross sectional studies cannot determine whether C. pneumoniae is a cause of atherosclerosis since they do not show whether infection precedes or follows its development. However, our results suggest that the organism is not an important factor in graft failure or atherosclerosis.