Detection of Chlamydia pneumoniae in giant cell vasculitis and correlation with the topographic arrangement of tissue-infiltrating dendritic cells

Fate of Chlamydophila pneumoniae in human monocyte-derived dendritic cells: Long lasting infection

Earlier studies from this group demonstrated that Chlamydophila pneumoniae co-localized with dendritic cells (DC) in temporal artery biopsies from patients with giant cell arteritis (GCA). To investigate the interaction of DC with C. pneumoniae we employed an in vitro cell culture system of human monocyte derived DC. These DC were infected with C. pneumoniae and observed at regular time intervals up to 25 days post infection. Chlamydiae were visualized inside DC by both confocal and electron microscopy. Statistical analysis showed an increase in the number of chlamydial antigen during that period (p < 0.00005, chi2-test). Titration of DC lysates on HEp-2 cells showed that infectious progeny was recovered at various intervals but showed no exponential growth. Additionally, RT-PCR analyses of infected DC identified transcripts from dnaA, ftsK and tal throughout a period of 14 days, indicating viable chlamydiae. Thus, human monocyte-derived DC are susceptible to C. pneumoniae infection. These results indicate that C. pneumoniae-infected DC can play an important role in the transmission of these bacteria in GCA and other chlamydial diseases.

Vasculitis and systemic infections

PURPOSE OF REVIEW

In recent years, many investigators have focused on potential associations between infections and vascular inflammation. We review the principal pathogenic mechanisms that have been implicated for possible roles in the vascular inflammation initiated by infectious agents. We also summarize the most important literature related to this topic.

RECENT FINDINGS

A novel theory known as autoantigen complementarity suggests that an infectious agent could trigger antineutrophil cytoplasmic antibody-associated vasculitis. Several recent studies investigating the presence of parvovirus B19 and herpesviruses in temporal arteries with giant cell arteritis have yielded contradictory results. A recent study has identified higher frequency of a novel human virus, the 'New Haven coronavirus', in respiratory secretions of children with Kawasaki disease. Many case reports have suggested potential relationships between human pathogens and vasculitis.

SUMMARY

There remains considerable interest in the possibilities of primary vasculitic syndromes caused in some fashion by infection. With the exception of a few well sustained associations - for example hepatitis B or C with known vasculitic syndromes - most of the purported links between microbial agents and primary vasculitides remain speculative.

Giant cell (temporal) arteritis: an overview and update

Giant cell arteritis is a systemic disease that continues to be a sight-threatening medical emergency requiring prompt recognition and treatment in order to avoid devastating ophthalmic consequences. Although there have been advances in the genetic and immunologic understanding of the underlying pathogenesis of the disease, the exact etiology of the condition, to date, remains unclear. Visual manifestations of giant cell arteritis are the common mode of presentation, making the ophthalmologist critically responsible for early diagnosis and treatment. Although temporal artery biopsy remains the only confirmatory procedure, newer laboratory investigations and blood flow studies with fundus fluorescein angiography have aided in the diagnosis of temporal giant cell arteritis. Maintenance of a high index of clinical suspicion is essential to institute prompt adequate treatment, especially in atypical cases. Corticosteroids remain the mainstay of treatment of giant cell arteritis. Recently, immunosuppressive agents as secondary steroid-sparing drugs have been used, particularly in some steroid-resistant cases. A wider recognition of the disease will minimize the prevalence of irreversible visual loss among patients with giant cell arteritis.

Systemic effects of periodontal diseases

A number of studies suggest an association between periodontal disease and cardiovascular disease, pulmonary disease, diabetes,and pregnancy complications. Presently, the data must be regarded as preliminary. Additional large-scale longitudinal epidemiologic and interventional studies are necessary to validate these associations and to determine whether the associations are causal. The goal of this article is to review the history of this concept, describe the biologically plausible circumstances that may underlie these potential associations, and provide a summary of the published literature that supports or refutes them.

How to diagnose and treat secondary forms of vasculitis

Vasculitis is considered to be secondary when it arises either in the context of a pre-existing connective tissue disease, as a result of direct infection with a limited range of organisms, especially viruses, or when it arises in response to exposure to a number of medications. Rheumatoid vasculitis is probably the most widely recognised form of secondary vasculitis, and in this article we review the incidence, clinical features and management of this condition. Infections may either trigger or cause some types of vasculitis. Drug therapy is a common cause of limited forms of vasculitis and may enhance our understanding of the mechanism of these diseases. The premature development of atherosclerosis in patients with existing connective tissue diseases or indeed primary vasculitis has been recognised for some time, and the underlying mechanisms are currently being studied. An appreciation of the complex and varied pathophysiology of secondary vasculitis may further our understanding of primary vasculitis.

Giant cell arteritis and cardiovascular disease in older adults

OBJECTIVE

To explore the association between giant cell arteritis (GCA) and subsequent cardiovascular disease in older adults.

DESIGN

Population based retrospective cohort study.

SETTING

The entire province of Ontario, Canada.

PARTICIPANTS

Patients aged 66 years and older with newly diagnosed GCA (n = 1141), osteoarthritis (n = 172,953), or neither (n = 200,000). Patients with neither were randomly selected from the general population and formed the control group.

MAIN OUTCOME MEASURES

The primary composite outcome was based on a subsequent diagnosis or surgical treatment for coronary artery disease, stroke, peripheral arterial disease, or aneurysm or dissection of the aorta.

RESULTS

The composite end point was more common in seniors with GCA (12.1/1000 person-years) than in patients with osteoarthritis (7.3/1000 person-years) or neither condition (5.3/1000 person-years). The adjusted hazard ratio for cardiovascular disease was 1.6 (95% confidence interval (CI) 1.1 to 2.2) in patients with GCA versus patients with osteoarthritis, and 2.1 (95% CI 1.5 to 3.0) in patients with GCA versus unaffected controls.

CONCLUSIONS

Older adults with GCA appear to be at increased risk for developing cardiovascular disease. Whether an aggressive approach to cardiovascular risk factor modification is particularly beneficial in these patients remains to be determined.

Amplification of autoimmune disease by infection

Reports of infection with certain chronic persistent microbes (herpesviruses or Chlamydiae) in human autoimmune diseases are consistent with the hypothesis that these microbes are reactivated in the setting of immunodeficiency and often target the site of autoimmune inflammation. New experimental animal models demonstrate the principle. A herpesvirus or Chlamydia species can be used to infect mice with induced transient autoimmune diseases. This results in increased disease severity and even relapse. The evidence suggests that the organisms are specifically imported to the inflammatory sites and cause further tissue destruction, especially when the host is immunosuppressed. We review the evidence for the amplification of autoimmune inflammatory disease by microbial infection, which may be a general mechanism applicable to many human diseases. We suggest that patients with autoimmune disorders receiving immunosuppressing drugs should benefit from preventive antiviral therapy.

Is giant cell arteritis an infectious disease?

The etiology of giant cell arteritis and polymyalgia rheumatica remains unknown, although the HLA-DR4 group and the pre-existence of a degenerative vascular disease are confirmed risk factors. The incidence may vary between countries, but the North-South gradient should be considered with caution because of potential detection and collection bias. Infectious trigger factors have been looked for both at the epidemiological and biological level: annual, cyclic variations of incidence have been shown in Minnesota, seasonal variations in Scotland, France or Israel. The pre-existence of clinical, mainly respiratory, infection has been suggested in one study, but not confirmed afterwards. Simultaneous occurrence of peaks of GCA/PMR and respiratory infections have been observed in Denmark. Several viruses have been suspected as triggers and assessed by serological testing, PCR or immunostaining on temporal artery biopsies, or both techniques: the hepatitis B virus can be ruled out, as well as Herpes simplex 1 and 2, Herpes varicellae, Epstein-Barr virus and cytomegalovirus. Recent studies focused on parainfluenza virus, Parvovirus B19 and Chlamydia pneumoniae. Immunological studies suggest, at the origin of the inflammatory reaction leading to the typical pathological features of giant cell arteritis, the existence of a triggering antigen of unknown nature activating T-cells in the artery wall.

Identification of candidate microbial sequences from inflammatory lesion of giant cell arteritis

Giant cell arteritis (GCA) is a granulomatous inflammatory disease of medium and large arteries which is prevalent in the elderly population. The etiology of GCA is unknown, although the immunologic features suggest the possible presence of a microorganism. Our group has examined whether microbial DNA fragments were present at GCA lesions and whether such microbial fragments could be associated with disease pathogenesis. Initial identification of microbial sequences was performed using genomic representational difference analysis (RDA). Laser dissecting microscopy was used to isolate cells from GCA lesions and adjacent uninvolved temporal artery. Using genomic RDA, we isolated 10 gene fragments; three of these sequences had high homology with prokaryotic genes and were considered high-priority candidates for further study. An examination of serum from GCA(+) individuals (in contrast to healthy age-matched controls) showed the presence of IgG which recognized in vitro translated proteins from these clones.

Are polymyalgia rheumatica and giant cell arteritis the same disease?

OBJECTIVE

To summarize the evidence about the relationship between polymyalgia rheumatica (PMR) and giant cell arteritis (GCA).

METHODS

Review of relevant articles from the English-language literature.

RESULTS

Epidemiologic studies suggest that PMR and GCA are closely related conditions affecting people over 50 years and frequently occurring in the same patient. PMR symptoms have been observed in 40 to 60 percent of GCA clinical series. Also, temporal artery biopsy may yield positive results for GCA in patients with isolated PMR. Conflicting HLA-DRB1 genotype results have been reported, and recent studies have shown that PMR and GCA have different expression of RANTES, TNFalpha microsatellite, and IL-6 promoter genetic polymorphisms. Search for a possible common infectious agent have yielded disappointing results. Although parvovirus B19 DNA is present in the artery wall of patients with GCA, this virus may be only an innocent bystander. Cytokine studies on a limited number of temporal artery biopsy specimens have shown that interferon-gamma is produced in GCA and not in PMR, suggesting that this cytokine may be crucial to the development of overt vasculitis.

CONCLUSIONS

PMR and GCA frequently occur together but no definitive conclusions can be drawn about the nature of this association.

Associations between periodontal disease and risk for atherosclerosis, cardiovascular disease, and stroke. A systematic review

BACKGROUND

Recent studies implicate exposure to systemic conditions involving chronic inflammation, including chronic periodontitis, in the etiology of atherosclerosis.

RATIONALE

A systematic review of the literature was conducted to assess the association between chronic inflammatory periodontal disease and atherosclerosis.

FOCUSED QUESTION

Does periodontal disease influence the initiation/progression of atherosclerosis and, therefore, cardiovascular disease (CVD), stroke, and peripheral vascular disease (PVD)?

SEARCH PROTOCOL

MEDLINE, pre-MEDLINE, MEDLINE Daily Update, and the Cochrane Controlled Trials Register were searched to identify human studies that related variables associated with atherosclerosis to periodontal disease. Searches were made for papers published from 1966 through March 2002.

INCLUSION CRITERIA

Published randomized controlled clinical trials (RCTs), longitudinal, cohort, and case-control studies were included. Study participants included those with atherosclerosis, myocardial infarction (MI), stroke, or PVD. Oral conditions included periodontal disease.

EXCLUSION CRITERIA

Only studies on humans were included.

DATA COLLECTION AND ANALYSIS

Because the studies used different oral assessment measures, it was not possible to perform a meta-analysis of the data reported. Weighted mean differences, relative risks, or odds ratios were compared for cohort studies.

MAIN RESULTS

1. Of the initial 1,526 studies identified, 31 (including 8 case-control and 18 cross-sectional reports) were included in the analysis. Taken together, most of the literature supports a modest association between periodontal disease and atherosclerosis. However, data reported in several studies do not show this association. 2. The absence of a standard definition and measures for periodontal disease complicates interpretation of results, as do potential confounding risk factors common to both conditions.

REVIEWERS' CONCLUSIONS

1. Periodontal disease may be modestly associated with atherosclerosis, MI, and CVD. 2. Additional large-scale longitudinal epidemiologic and intervention studies are necessary to validate this association and to determine causality.

Giant cell arteritis

Giant cell arteritis (GCA), temporal arteritis or Horton's arteritis, is a systemic vasculitis which involves large and medium sized vessels, especially the extracranial branches of the carotid arteries, in persons usually older than 50 years. Permanent visual loss, ischaemic strokes, and thoracic and abdominal aortic aneurysms are feared complications of GCA. The treatment consists of high dose steroids. Mortality, with a correct treatment, in patients with GCA seems to be similar that of controls.

Do temporal arteritis lesions contain bacterial DNA?

BACKGROUND

Temporal arteritis is a primary vascular inflammatory disease. The aetiology of temporal arteritis is unknown, but the influence of environmental factors such as infections has been suggested.

MATERIALS AND METHODS

We used broad-range PCR, targeting conserved regions of the gene encoding for ribosomal RNA, to detect bacterial DNA in 27 temporal artery biopsies. Five uninvolved temporal arteries were also included. A lung sample of confirmed bacterial pneumonia served as a positive control. Inflammation was examined by histochemistry and light microscopy.

RESULTS

The sensitivity of the broad-range PCR assay was 5.0 fg of DNA. Bacterial DNA sequences were neither detected in 27 temporal arteritis specimens nor in the normal temporal artery samples. However, bacterial DNA was successfully amplified from the lung sample of a subject with pneumonia. In addition, human DNA was amplified by primers for human beta-actin from all clinical specimens, suggesting lack of significant inhibitors of the molecular amplification reaction. Histochemistry showed signs of strong inflammation in the arteritis samples.

CONCLUSIONS

The lack of detectable amounts of bacterial DNA suggests that viable bacteria do not have a role in chronic stages of temporal arteritis. However, these findings do not rule out the possibility of bacterial degradation products as stimulants of chronic inflammation, or of viable microbes as triggering factors of acute temporal arteritis.

Temporal arteritis and Chlamydia pneumoniae: failure to detect the organism by polymerase chain reaction in ninety cases and ninety controls

OBJECTIVE

To examine the reported correlation between the presence of Chlamydia pneumoniae in temporal artery biopsy specimens and the diagnosis of temporal arteritis (TA).

METHODS

Among 90 possible cases of TA identified at our institution between 1968 and 2000, 79 of the positive biopsy specimens (88%) demonstrated giant cells and the other 11 cases (12%) had other histopathologic features compatible with TA; by chart review, all 90 patients were confirmed to have met the American College of Rheumatology classification criteria for TA. Controls had negative temporal artery biopsy specimens during the same 32-year time period and their postbiopsy disease courses were not compatible with TA. Controls were matched with each case by sex, year of biopsy, and age within 10 years. The biopsy specimens from all cases and controls were reevaluated and readings were confirmed in a masked manner by an experienced eye pathologist. Polymerase chain reaction (PCR) analyses for C pneumoniae were performed on the 180 samples using 2 different sets of PCR primers (which target 2 different genes). A primer set targeting the ompA gene (CP1-CP2/CPC-CPD) was used to perform a nested PCR, followed by confirmation of the findings with primers targeting the 16S ribosomal RNA (rRNA) gene (Cpn90/Cpn91) in a touchdown-enzyme time-release PCR. We used positive and negative controls, as well as controls made from infected and noninfected HEp-2 cells, suspended in a formalin-fixed, paraffin-embedded matrix.

RESULTS

Seventy-six percent of the 180 cases and controls were women. The mean age of the cases was 72.0 years (range 53-90), and that of the controls was 70.4 years (range 51-86). Eighty percent of the control samples were obtained by temporal artery biopsy performed within 1 year of the biopsies performed on the matched cases. Using the CP1-CP2/CPC-CPD primer set, only 1 TA case sample (1% of all case samples) was positive for the ompA gene. One control sample was also positive using these primers. With the Cpn90/Cpn91 primers, none of the cases and none of the controls were positive for the 16S rRNA gene.

CONCLUSION

The results of this study using sensitive and specific PCR analyses do not support a role for C pneumoniae in the pathogenesis of TA.

Analysis of the B cell repertoire against autoantigens in patients with giant cell arteritis and polymyalgia rheumatica

The analysis of the antibody repertoire of patients with giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) might identify target antigens of the autoimmune response with potential relevance to our understanding of the pathogenesis of the disease and to the development of serodiagnostic tests. To detect such antigens, we screened a cDNA library derived from normal human testis for antigens reacting with IgG antibodies in the 1 : 250 diluted sera of three patients with untreated GCA using SEREX, the serological identification of antigens by recombinant cDNA expression cloning. Of 100 000 clones screened with each serum, six, 28 and six clones, respectively, were positive, representing a total of 33 different antigens. Most of the antigens reacted only with the serum used for identification and/or at a similar frequency with normal control sera. However, lamin C and the nuclear antigen of 14 kD reacted specifically with 32% of GCA/PMR, but with none of the control sera, while human cytokeratin 15, mitochondrial cytochrome oxidase subunit II, and a new gene product were detected preferentially, but not exclusively by sera from GCA/PMR patients. We conclude that patients with GCA/PMR develop antibodies against a broad spectrum of human autoantigens. Antibodies against human lamin C, the nuclear autoantigen of 14 kD as well as human cytokeratin 15, mitochondrial cytochrome oxidase subunit II and the product of a new gene should be investigated further to determine their value as tools for the diagnosis and/or the definition of clinical subgroups of patients with GCA/PMR.

Giant cell arteritis

Giant cell arteritis (GCA), the most common form of systemic vasculitis in adults, preferentially involves large and medium-sized arteries in patients over the age of 50. The classic manifestations are headache, jaw claudication, polymyalgia rheumatica (PMR), and visual symptoms, but 40% of patients present with a wide range of occult manifestations. Early diagnosis and treatment with prednisone can prevent blindness, the most feared complication of GCA. The pathogenesis of GCA is T-cell dependent and antigen driven. Clinical subsets of GCA appear to result from variable cytokine expression. The risk of developing thoracic aortic aneurysm is increased more than 17-fold in patients with GCA. GCA can also involve large arteries, especially the subclavian and axillary arteries. Color Doppler ultrasound, magnetic resonance imaging, and positron-emission tomography scanning are providing insights into the extent and pathogenesis of the disease but have not replaced temporal artery biopsy as the gold standard for securing the diagnosis. Two recently completed double-blind, placebo-controlled trials concerning whether methotrexate plus prednisone is more effective than prednisone alone reached conflicting conclusions.

Evaluation of real-time quantitative PCR for identification and quantification of Chlamydia pneumoniae by comparison with immunohistochemistry

Chlamydia pneumoniae is a common cause of community-acquired pneumonia and it has been associated with atherosclerosis. C. pneumoniae has usually been diagnosed by serology using a microimmunofluorescence test, but more recently polymerase chain reaction (PCR) has been viewed as an advantageous alternative. We developed a quantitative real-time PCR for detection of C. pneumoniae. Primers were targeted for the pmp4 gene, and the PCR fragment was detected real-time with a fluorescence resonance energy transfer probe set using a LightCycler instrument. The PCR was used on DNA released from 50 microm sections of paraffin-embedded formalin-fixed lung tissue from experimentally infected mice. Thereby, the number of C. pneumoniae genomes was determined. To our knowledge this is the first time quantification of C. pneumoniae DNA has been attempted on paraffin-embedded formalin-fixed tissue. C. pneumoniae-specific immunohistochemistry (IHC) was done on 5 microm sections adjacent to the sections used in PCR, and the number of inclusions were counted in each section. Good correlation was found when comparing results from PCR and IHC, which is in contrast to many previous studies.

Polymyalgia Rheumatica and Temporal Arteritis with Sacroiliitis and Osteitis Pubis

Polymyalgia rheumatica (PMR) and temporal arteritis (TA) have been associated with a seronegative polyarthritis that can mimic rheumatoid arthritis. Sacroiliitis and osteitis pubis are most often encountered in the different types of spondyloarthropathy. However, sacroiliitis and osteitis pubis have rarely been described in patients with polymyalgia rheumatica and temporal arteritis. We present two patients, one with temporal arteritis and the other with polymyalgia rheumatica, who also had many features of a spondyloarthropathy, including sacroiliitis and osteitis pubis. In reviewing the literature, we found 30 other patients with a diagnosis of PMR who also had sacroiliitis and/or osteitis pubis. We propose that the inflammatory arthritis associated with polymyalgia rheumatica and temporal arteritis can involve the axial joints, resembling a spondyloarthropathy. It is important for the clinician to recognize that sacroiliitis and osteitis pubis have been associated with PMR and TA so that their radiographic presence does not dissuade the clinician from making the correct diagnosis.

Chlamydia pneumoniae infection of the central nervous system

Chlamydia pneumoniae is a common respiratory pathogen that is now being implicated in a number of chronic diseases. That the organism can infect vascular endothelium, macrophages and smooth muscle cells suggests that it may play a role in many systemic diseases. The present review focuses on the possibility that the central nervous system can also be a target of this agent. The tropism of C. pneumoniae to the neural tissue suggests it may play a role in diverse neurologic diseases, including Alzheimer's disease, multiple sclerosis and giant-cell arteritis.

The anti-idiotypic antibody to chlamydial glycolipid exoantigen (GLXA) protects mice against genital infection with a human biovar of Chlamydia trachomatis

Despite more than three decades of anti-chlamydial vaccine research and improved vaccine strategies with new technologies, no vaccine candidate has protected against heterologous challenge, nor at more than one site of infection. The majority of experimental anti-chlamydial vaccines to date have targeted the chlamydial major outer membrane protein (MOMP). Many MOMP-directed vaccine candidates have been highly immunogenic, but have failed to protect against infectious challenge. We have extended our previous studies of a different anti-chlamydial vaccine, a monoclonal anti-idiotypic antibody (anti-Id; mAb2) which is a molecular mimic of the chlamydial glycolipid exoantigen (GLXA). The present studies demonstrate that the mAb2 vaccine is protective in a murine genital infection model utilizing a human urogenital strain. After either mucosal (oral or intranasal) or systemic (subcutaneous) immunization with the poly (lactide) encapsulated-mAb2 to GLXA, C3H/HeJ mice were significantly protected against topical vaginal challenge with Chlamydia trachomatis (K serovar; UW-31). Reduced vaginal shedding of organism and genital tract inflammation were associated with GLXA-specific and/or anti-EB neutralizing serum antibody. Our results demonstrate that the anti-Id (mAb2) vaccine is protective against an additional human biovar of C. trachomatis in C3H/HeJ mice, which are allogeneic to the source of mAb2 (BALB/c).

Tissue targeting and disease patterns in systemic vasculitis

The systemic vasculitides include a group of diseases with highly heterogeneous organ distribution and disease expression patterns. The mechanisms mediating tissue targeting in systemic vasculitis are largely unknown. Mechanical forces may contribute to the distribution of lesions in immune complex-mediated vasculitis. The site at which the antigen is encountered may be crucial in determining the location of inflammatory infiltrates in some vasculitides. Co-existence of different immunopathogenic mechanisms with variable dominance may generate diversity in disease presentation patterns. Heterogeneous and incompletely understood triggering mechanisms attract inflammatory cells to the site of interest through sophisticated molecular mechanisms: interplay between leukocyte receptors and endothelial ligands, and interactions between chemokines and chemokine receptors. Even with a similar distribution of lesions, patients with vasculitis may display highly variable clinical manifestations. Variations in genes involved in immune response might determine the severity of disease, the intensity of the systemic inflammatory response, the degree of vessel occlusion and the response to therapy.

A possible association between Chlamydiae psittacci infection and temporal arteritis

Some arguments are in favor of the role of Chlamydia in the pathogenesis of atherosclerosis and some vasculitis. Illustrating this possible relation, we report the case of a patient developing consecutively a Chlamydia psittacci infection and a temporal arteritis. A 73-year-old woman, with no significant medical history, was hospitalized for constitutional symptoms. Three weeks before, she had described fever and sore throat of two days' duration. Since that time, she had remained exhausted and developed a mild intermittent claudication of the jaws. Clinical examination was poor. A biological inflammatory syndrome was noticed. Chest X-ray revealed bilateral interstitial opacities. The titer of anti-C. psittaci antibodies was significant (positive 1g G at 1/2048). Soon after initiation of doxycycline, a temporal arteritis biopsy was performed, due to the persistence of clinical symptoms and high inflammatory syndrome, conclusive for the diagnosis of temporal arteritis. Corticotherapy was added to antibiotic therapy, resulting in the decrease of inflammatory syndrome and an improvement in the general status of the patient. X-ray opacities decreased in three weeks. Serological control after three months showed a decrease of the titer of anti-C. psittacci antibodies to 1/256, confirming the initial diagnosis of Chlamydia pneumopathy. Our observation could provide one more argument for the role of bacteria-like Chlamydia in the pathogenesis of vascular diseases. Prospective seroepidemiological and molecular biology studies could allow us to clarify the association between Chlamydia infections and inflammatory vasculitis-like temporal arteritis.