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

Does Dementia Have a Microbial Cause?

The potential contribution of pathogenic microbes to dementia-inducing disease is a subject of considerable importance. Alzheimer’s disease (AD) is a neurocognitive disease that slowly destroys brain function, leading to cognitive decline and behavioral and psychiatric disorders. The histopathology of AD is associated with neuronal loss and progressive synaptic dysfunction, accompanied by the deposition of amyloid-β (Aβ) peptide in the form of parenchymal plaques and abnormal aggregated tau protein in the form of neurofibrillary tangles. Observational, epidemiological, experimental, and pathological studies have generated evidence for the complexity and possible polymicrobial causality in dementia-inducing diseases. The AD pathogen hypothesis states that pathogens and microbes act as triggers, interacting with genetic factors to initiate the accumulation of Aβ, hyperphosphorylated tau protein (p-tau), and inflammation in the brain. Evidence indicates that Borrelia sp., HSV-1, VZV (HHV-2), HHV-6/7, oral pathogens, Chlamydophila pneumoniae, and Candida albicans can infect the central nervous system (CNS), evade the immune system, and consequently prevail in the AD brain. Researchers have made significant progress in understanding the multifactorial and overlapping factors that are thought to take part in the etiopathogenesis of dementia; however, the cause of AD remains unclear.

Diagnosis and management of giant cell arteritis: Major review

Giant cell arteritis is a medical emergency because of the high risk of irreversible blindness and cerebrovascular accidents. While elevated inflammatory markers, temporal artery biopsy and modern imaging modalities are useful diagnostic aids, thorough history taking and clinical acumen still remain key elements in establishing a timely diagnosis. Glucocorticoids are the cornerstone of treatment but are associated with high relapse rates and side effects. Targeted biologic agents may open up new treatment approaches in the future.

Perspectives on the Intracellular Bacterium Chlamydia pneumoniae in Late-Onset Dementia

Purpose of Review

Chronic diseases remain a daunting challenge for clinicians and researchers alike. While difficult to completely understand, most chronic diseases, including late-onset dementias, are thought to arise as an interplay between host genetic factors and environmental insults. One of the most diverse and ubiquitous environmental insults centers on infectious agents. Associations of infectious agents with late-onset dementia have taken on heightened importance, including our investigations of infection by the intracellular respiratory bacterium, Chlamydia pneumoniae (Cpn), in late-onset dementia of the Alzheimer’s type.

Recent Findings

Over the last two decades, the relationship of this infection to pathogenesis in late-onset dementia has become much clearer. This clarity has resulted from applying contemporary molecular genetic, biochemical, immunochemical, and cell culture techniques to analysis of human brains, animal models, and relevant in vitro cell culture systems. Data from these studies, taken in aggregate form, now can be applied to evaluation of proof of concept for causation of this infection with late-onset disease. In this evaluation, modifications to the original Koch postulates can be useful for elucidating causation.

Summary

All such relevant studies are outlined and summarized in this review, and they demonstrate the utility of applying modified Koch postulates to the etiology of late-onset dementia of the Alzheimer’s type. Regardless, it is clear that even with strong observational evidence, in combination with application of modifications of Koch’s postulates, we will not be able to conclusively state that Cpn infection is causative for disease pathogenesis in late-onset dementia. Moreover, this conclusion obtains as well for the putative causation of this condition by other pathogens, including herpes simplex virus type 1, Borrelia burgdorferi, and Porphyromonas gingivalis.

[Physiopathology of giant cell arteritis: From inflammation to vascular remodeling]

Giant cell arteritis (GCA) is a large-vessel vasculitis involving the aorta and its main branches, especially supra aortic branches. Although much progress has been made, the pathophysiology remains incompletely understood. An initial trigger, suspected of infectious origin, lead to the maturation and recruitment of dendritic cells (DC). The lack of migration of these DC allows the local recruitment of T-lymphocytes (LT). These LT- CD4⁺ polarize in Type 1 helper (Th1), Th17 but also Th9. A qualitative and quantitative deficit in regulatory T cells (Treg) is observed under the influence of IL-21 overproduction. In addition, an imbalance in the Th17/Treg balance is favored by IL-6. The secretion of IFN-γ, IL-17, IL-6, IL-33 is responsible for a sustained local inflammatory reaction that is organized around tertiary lymphoid follicles. Locally recruited macrophages secrete reactive forms of oxygen together with VEGF and PDGF. These growth factors, together with neurotrophins and endothelin contribute to increase the proliferation of vascular smooth muscle cells (VSMCs). The imbalance between matrix metalloproteases (MMP)-2, MMP-9 and MMP-14 and tissue inhibitors of metalloproteases (TIMP)-1 and TIMP-2 also contribute to the remodeling process occurring in the vessel wall. Finally, arterial neovascularization contribute to the perpetuation of lymphocyte recruitment. This persistent remodeling is sometimes complicated by ischemic events responsible for the initial severity of the disease.

Spontaneous remission of giant cell arteritis: possible association with a preceding acute respiratory infection and seropositivity to Chlamydia pneumoniae antibodies

Recent epidemiological or immunopathological studies demonstrate the possible association between giant cell arteritis and infectious agents including Chlamydia pneumoniae. A 62-year-old Japanese man with type 1 diabetes mellitus developed biopsy-proven giant cell arteritis after acute upper respiratory infection. Serological examination indicated concurrent re-infection with C. pneumoniae. Clinical manifestations of the vasculitis subsided within a month without any immunosuppressive therapy, and no relapse was observed for the following 12 months. The natural history of this disease is unclear and spontaneous remission is rarely reported. The self-limiting nature of the infection could contribute to this phenomenon.

Microbiomes of Inflammatory Thoracic Aortic Aneurysms Due to Giant Cell Arteritis and Clinically Isolated Aortitis Differ From Those of Non-Inflammatory Aneurysms

OBJECTIVE

We sought to characterize microbiomes of thoracic aortas from patients with non-infectious aortitis due to giant cell arteritis (GCA) and clinically isolated aortitis (CIA) and to compare them to non-inflammatory aorta aneurysm controls. We also compared microbiomes from concurrently processed and separately reported temporal arteries (TA) and aortas.

METHODS

From 220 prospectively enrolled patients undergoing surgery for thoracic aorta aneurysm, 49 were selected. Inflammatory and non-inflammatory cases were selected based on ability to match for age (+/-10 years), gender, and race. Biopsies were collected under aseptic conditions and snap-frozen. Taxonomic classification of bacterial sequences was performed to the genus level and relative abundances were calculated. Microbiome differential abundances were analyzed by principal coordinates analysis.

RESULTS

Forty-nine patients with thoracic aortic aneurysms (12 CIA, 14 GCA, 23 non-inflammatory aneurysms) were enrolled. Alpha (P=0.018) and beta (P=0.024) diversity differed between specimens from aortitis cases and controls. There were no significant differences between CIA and GCA (P>0.7). The largest differential abundances between non-infectious aortitis and non-inflammatory control samples included Enterobacteriaceae, Phascolarctobacterium, Acinetobactor, Klebsiella, and Prevotella. Functional metagenomic predictions with PICRUSt revealed enrichment of oxidative phosphorylation and porphyrin metabolism pathways and downregulation of transcription factor pathways in aortitis compared to controls. Microbiomes of aortic samples differed significantly from temporal artery samples from a companion study, in both control and GCA groups (P=0.0002).

CONCLUSION

Thoracic aorta aneurysms, far from being sterile, contain unique microbiomes that differ from those found in temporal arteries. The aorta microbiomes are most similar between aneurysms that were associated with inflammation, GCA, and CIA, but differed from those associated with non-inflammatory etiologies. These findings are promising in that they indicate that microbes may play a role in the pathogenesis of aortitis-associated aneurysms or non-inflammatory aneurysms by promoting or protecting against inflammation. However, we cannot rule out that these changes are related to alterations in tissue substrate that favor secondary changes in microbial communities.

The Microbiome of Temporal Arteries

Objective

A role for microorganisms in giant cell arteritis (GCA) has long been suspected. We describe the microbiomes of temporal arteries from patients with GCA and controls.

Methods

Temporal artery biopsies from patients suspected to have GCA were collected under aseptic conditions and snap-frozen. Fluorescence in situ hybridization (FISH) and long-read 16S rRNA-gene sequencing was used to examine microbiomes of temporal arteries. Taxonomic classification of bacterial sequences was performed to the genus level and relative abundances were calculated. Microbiome differential abundances were analyzed by principal coordinate analysis (PCoA) with comparative Unifrac distances and predicted functional profiling using PICRUSt.

Results

Forty-seven patients, including 9 with biopsy-positive GCA, 15 with biopsy-negative GCA and 23 controls without GCA, were enrolled. FISH for bacterial DNA revealed signal in the arterial media. Beta, but not alpha, diversity differed between GCA and control temporal arteries (P = 0.042). Importantly, there were no significant differences between biopsy-positive and biopsy-negative GCA (P > 0.99). The largest differential abundances seen between GCA and non-GCA temporal arteries included Proteobacteria (P), Bifidobacterium (g), Parasutterella (g), and Granulicatella (g) [Log 2-fold change ≥ 4].

Conclusion

Temporal arteries are not sterile, but rather are inhabited by a community of bacteria. We have demonstrated that there are microbiomic differences between GCA and non-GCA temporal arteries, but not between biopsy-positive and biopsy-negative GCA.

The Treatment of Giant Cell Arteritis in Different Clinical Settings

This paper aims to raise awareness of the different disease courses, comorbidities, and therapy situations in patients with giant cell arteritis (GCA), which require a differentiated approach and often a deviation from current treatment guidelines. With the approval of tocilizumab (TOC), which specifically binds to both soluble and membrane-bound IL-6 receptor and inhibits IL-6 receptor-mediated signaling, the spectrum of available effective treatment options has been significantly broadened. TOC yields an extensive range of possible applications that go beyond a glucocorticoid-saving effect. In this context, the treatment of GCA is dependent on the disease course as well as the associated comorbidities. The different stages of GCA in association to co-morbidities require a detailed treatment strategy.

Does low risk of infections as a marker of effective immunity predict increased risk of subsequent giant cell arteritis or polymyalgia rheumatica? A Danish population-based case-control study

Objective

It has been suggested that a hyper-effective immune system (“hyper-immunity”) is central to the pathogenesis of giant cell arteritis and polymyalgia rheumatica (GCA/PMR). We examined if a low risk of infections, as a marker of hyper-immunity, can predict increased subsequent risk of GCA/PMR.

Patients and methods

We conducted a population-based case–control study including all patients aged ≥50 years with incident GCA/PMR diagnosed between 1997 and 2012 in Northern Denmark. For each case, we selected 10 population controls matched on gender, age, place of residence, and time spent in the region. Complete history of hospital-treated infections and community-based anti-infective prescriptions was assessed in population-based registries. We used conditional logistic regression to compute OR of GCA/PMR associated with infections while adjusting for comorbidities, immunosuppressive treatment, and other potential confounders.

Results

We included 7,225 GCA/PMR cases and 72,250 controls. When excluding all infections occurring within the last year before GCA/PMR diagnosis, there was no decreased risk for GCA/PMR in people with a history of hospital-treated infection (adjusted OR=1.04, 95% CI: 0.98–1.10) or community anti-infective treatment (adjusted OR=1.07, 95% CI: 0.99–1.16). Within the last year preceding the GCA/PMR index date, patients with hospital-treated infections (adjusted OR=1.59, 95% CI: 1.44–1.75) or community anti-infective treatment (adjusted OR=1.63, 95% CI: 1.48–1.79) had a greatly increased risk of a GCA/PMR diagnosis.

Conclusion

These results do not support the hypothesis of “hyper-immunity” leading to GCA/PMR. Instead, incident GCA/PMR is preceded by a slightly increased risk of infection, which may be related to protopathic bias or support theories that infections may be directly involved in the pathogenesis of GCA/PMR.

Pathogenesis of large vessel vasculitis: Implications for disease classification and future therapies

Despite being recognised over a century ago, the aetiology and pathogenesis of large vessel vasculitis (LVV) still remains elusive. Takayasu’s arteritis (TA) and giant cell arteritis (GCA) represent the two major categories of LVV, each with distinctive clinical features. Over the last 10 years an increased understanding of the immunopathogenesis of the inflammatory cascade within the aortic wall has revived the view that LVVs may represent subtypes of the same pathological process, with implications in the treatment of this disease. In this review, the histological, genetic and immunopathological features of TA and GCA will be discussed and the evidence for a common underlying disease mechanism examined. Novel markers of disease activity and therapies based on advances in our understanding of the immunopathogenesis of these conditions will also be discussed.

Chlamydia pneumoniae: An Etiologic Agent for Late-Onset Dementia

The disease known as late-onset Alzheimer's disease is a neurodegenerative condition recognized as the single most commonform of senile dementia. The condition is sporadic and has been attributed to neuronal damage and loss, both of which have been linked to the accumulation of protein deposits in the brain. Significant progress has been made over the past two decades regarding our overall understanding of the apparently pathogenic entities that arise in the affected brain, both for early-onset disease, which constitutes approximately 5% of all cases, as well as late-onset disease, which constitutes the remainder of cases. Observable neuropathology includes: neurofibrillary tangles, neuropil threads, neuritic senile plaques and often deposits of amyloid around the cerebrovasculature. Although many studies have provided a relatively detailed knowledge of these putatively pathogenic entities, understanding of the events that initiate and support the biological processes generating them and the subsequent observable neuropathology and neurodegeneration remain limited. This is especially true in the case of late-onset disease. Although early-onset Alzheimer's disease has been shown conclusively to have genetic roots, the detailed etiologic initiation of late-onset disease without such genetic origins has remained elusive. Over the last 15 years, current and ongoing work has implicated infection in the etiology and pathogenesis of late-onset dementia. Infectious agents reported to be associated with disease initiation are various, including several viruses and pathogenic bacterial species. We have reported extensively regarding an association between late-onset disease and infection with the intracellular bacterial pathogen Chlamydia pneumoniae. In this article, we review previously published data and recent results that support involvement of this unusual respiratory pathogen in disease induction and development. We further suggest several areas for future research that should elucidate details relating to those processes, and we argue for a change in the designation of the disease based on increased understanding of its clinical attributes.

Giant cell arteritis: pathogenic mechanisms and new potential therapeutic targets

Giant cell arteritis (GCA) is the most common idiopathic systemic vasculitis in persons aged 50 years or greater. Treatment options for GCA, to-date, have been limited and have consisted primarily of glucocorticoids. Significant advances in the understanding of the genetic and cellular mechanisms in GCA are leading to identification of potential pathogenic targets. The recent success of interleukin-6 blockade in the treatment of GCA has opened the landscape to targeted biologic therapy. T cells, particularly T helper 1 and T helper 17 cell lineages have been identified as key inflammatory cells in both active and chronic vascular inflammatory lesions. Therapeutic agents, including abatacept and ustekinumab, which can impede both vasculitogenic cell lines are of particular interest. Inhibition of signalling pathways, including the janus kinase-signal tranducers and activation of transcription (JAK-STAT) and Notch pathways are evolving options. Tocilizumab has shown clear benefit in both newly diagnosed and relapsing patients with GCA and approval of this medication for treatment of GCA has led to rapid incorporation into treatment regimens. More information is required to understand the long-term outcomes of tocilizumab and other investigational targeted therapeutics in the treatment of GCA.

Giant cell arteritis and polymyalgia rheumatica: current challenges and opportunities

The fields of giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) have advanced rapidly, resulting in a new understanding of these diseases. Fast-track strategies and improved awareness programmes that prevent irreversible sight loss through early diagnosis and treatment are a notable advance. Ultrasonography and other imaging techniques have been introduced into routine clinical practice and there have been promising reports on the efficacy of biologic agents, particularly IL-6 antagonists such as tocilizumab, in treating these conditions. Along with these developments, which should improve outcomes in patients with GCA and PMR, new questions and unmet needs have emerged; future research should address which pathogenetic mechanisms contribute to the different phases and clinical phenotypes of GCA, what role imaging has in the early diagnosis and monitoring of GCA and PMR, and in which patients and phases of these diseases novel biologic drugs should be used. This article discusses the implications of recent developments in our understanding of GCA and PMR, as well as the unmet needs concerning epidemiology, pathogenesis, imaging and treatment of these diseases.

The role of toll like receptors in giant cell arteritis

GCA is a common primary systemic vasculitis that results in granulomatous inflammation of medium to large arteries. Both innate and adaptive immune mechanisms combine to drive intimal hyperplasia, luminal stenosis and ultimately occlusion. While the pathogenesis of GCA is incompletely understood, the activation of resident adventitial dendritic cells via toll like receptors (TLRs) appears to be a crucial inciting event. Here we explore the role of TLRs in the pathogenesis of GCA, including their effects on dendritic cell and T cell activation and recruitment, putative infectious triggers for GCA and the potential of TLR inhibition as a novel therapeutic strategy in GCA.

Evidence for a vascular microbiome and its role in vessel health and disease

PURPOSE OF REVIEW

We have summarized available evidence for and against the presence of a vascular microbiome. Studies that have attempted to detect bacteria and viruses in blood vessels in both health and disease are critiqued in an attempt to explain contrary results that may be due to variations in methodology.

RECENT FINDINGS

Many studies have demonstrated the presence of both bacteria and viruses within diseased blood vessels. Evidence is most compelling in atherosclerosis; however, recent reports have raised questions about the potential role of microbes in nonatherosclerotic aortic aneurysms and vasculitis. Preliminary evidence also suggests that apparently normal vessels may harbor microbes. With the exception of certain viral infections (e.g. hepatitis C virus, HIV, Epstein-Barr virus, and cytomegalovirus) and infectious endocarditis, systemic vasculitides have not been convincingly associated with infectious agents. However, emerging data suggest that different communities of microbes may be present in noninflammatory and inflammatory large-vessel diseases. Whether variations in vascular microbial communities are the cause or a secondary result (epiphenomena) of vessel injury remains to be determined.

SUMMARY

Blood vessels may not be sterile. Future studies of microbes in vessel health and disease may provide important insights into disease pathogenesis and suggest new therapies for diseases now considered to be idiopathic and refractory.

New developments in giant cell arteritis

Giant cell arteritis (GCA) is a medium-to-large vessel vasculitis with potentially sight- and life- threatening complications. Our understanding of the pathogenesis, diagnosis, and treatment of GCA has advanced rapidly in recent times. The validity of using the American College of Rheumatology guidelines for diagnosis of GCA in a clinical setting has been robustly challenged. Erythrocyte sedimentation rate, an important marker of inflammation, is lowered by the use of statins and nonsteroidal anti-inflammatory drugs. Conversely, it may be falsely elevated with a low hematocrit. Despite the emergence of new diagnostic modalities, temporal artery biopsy remains the gold standard. Evidence suggests that shorter biopsy lengths and biopsies done weeks to months after initiation of steroid therapy are still useful. New imaging techniques such as positron emission tomography have shown that vascular inflammation in GCA is more widespread than originally thought. GCA, Takayasu arteritis, and polymyalgia rheumatica are no longer thought to exist as distinct entities and are more likely parts of a spectrum of disease. A range of immunosuppressive drugs have been used in conjunction with corticosteroids to treat GCA. In particular, interleukin-6 inhibitors are showing promise as a therapy.

14-3-3 in Thoracic Aortic Aneurysms: Identification of a Novel Autoantigen in Large Vessel Vasculitis

OBJECTIVE

Large vessel vasculitides (LVV) are a group of autoimmune diseases characterized by injury to and anatomic modifications of large vessels, including the aorta and its branch vessels. Disease etiology is unknown. This study was undertaken to identify antigen targets within affected vessel walls in aortic root, ascending aorta, and aortic arch surgical specimens from patients with LVV, including giant cell arteritis, Takayasu arteritis, and isolated focal aortitis.

METHODS

Thoracic aortic aneurysm specimens and autologous blood were acquired from consenting patients who underwent aorta reconstruction procedures. Aorta proteins were extracted from both patients with LVV and age-, race-, and sex-matched disease controls with noninflammatory aneurysms. A total of 108 serum samples from patients with LVV, matched controls, and controls with antinuclear antibodies, different forms of vasculitis, or sepsis were tested.

RESULTS

Evaluation of 108 serum samples and 22 aortic tissue specimens showed that 78% of patients with LVV produced antibodies to 14-3-3 proteins in the aortic wall (93.7% specificity), whereas controls were less likely to do so (6.7% produced antibodies). LVV patient sera contained autoantibody sufficient to immunoprecipitate 14-3-3 protein(s) from aortic lysates. Three of 7 isoforms of 14-3-3 were found to be up-regulated in aorta specimens from patients with LVV, and 2 isoforms (ε and ζ) were found to be antigenic in LVV.

CONCLUSION

This is the first study to use sterile, snap-frozen thoracic aorta biopsy specimens to identify autoantigens in LVV. Our findings indicate that 78% of patients with LVV have antibody reactivity to 14-3-3 protein(s). The precise role of these antibodies and 14-3-3 proteins in LVV pathogenesis deserves further study.

Retrospective analysis of the clinical course of patients treated for polymyalgia

BACKGROUND

Polymyalgia rheumatica is a chronic inflammatory rheumatic condition, for which the mainstay of treatment is corticosteroids. Here, we review the clinical course of treated patients initially presenting with polymyalgic symptoms.

METHODS

A retrospective audit was performed of patients who presented with a possible diagnosis of polymyalgia rheumatica. Biochemical markers and prednisone doses were assessed at the initial review, at one month, and 3, 6, and 12 months later.

RESULTS

A cohort of 135 patients was identified, comprising 91 females and 44 males of mean age 70.7 years. All patients were treated with oral prednisone at an initial mean dose of 21.3 mg. Mean baseline C-reactive protein level and erythrocyte sedimentation rate were 41.6 mg/L and 48.6 mm/hour, respectively. Following initiation of therapy, there was a dramatic and sustained decrease in both inflammatory markers. A clinical response was observed in 96.2% of patients, but remission was achieved in only 18.2%. Of those initially diagnosed with polymyalgia rheumatica, 24.8% were subsequently diagnosed with a different rheumatic condition.

CONCLUSION

The excellent response rate to corticosteroid therapy is well established in the literature, but in this research, remission rates were comparatively low during the 12-month study period. The current value of disease-modifying antirheumatic drugs and biologic therapy appears uncertain, and further trials to establish their precise role would be beneficial. A large portion of patients presenting with polymyalgia were eventually diagnosed to have another rheumatic disease, thus reflecting the broad differential diagnosis of polymyalgia symptoms. Polymyalgia symptoms can occur in patients with polymyalgia rheumatica and other rheumatic conditions. This group has a good response to prednisone therapy, although remission at 12 months appears to be uncommon. The gold standard of treatment remains corticosteroid therapy.

NKG2D stimulated T-cell autoreactivity in giant cell arteritis and polymyalgia rheumatica

OBJECTIVE

To investigate functional expression of NKG2D on CD4 and CD8 T-cells in patients with giant cell arteritis (GCA) and polymyalgia rheumatica (PMR).

METHODS

Peripheral blood was drawn from patients with GCA (n=16), PMR (n=78) and healthy controls (HC, n=64). Tissue samples were obtained from GCA patients and controls. Proliferation and cytokine production assays were performed using CFSE and intracellular IFN-γ or TNF-α staining, respectively, and flow cytometry analysis. Immunofluorescence and immunohistology were applied to analyse the presence of NKG2D-expressing T-cells and NKG2D-ligands in temporal arteries, respectively. mRNA levels of NKG2D-ligands were determined by RT-PCR.

RESULTS

In both GCA and PMR patients, NKG2D was preferentially expressed on senescent CD4CD28(-) and CD8CD28(-), as well as on CD8CD28 T-cells. Frequencies of senescent T-cells were increased in GCA and PMR patients compared to HC. In GCA tissue samples, infiltrating T-cells were predominately CD28(-). NKG2D expressing T-cells concentrated around the vasa vasorum of the adventitia. Antigenic stimulation induced rapid up-regulation of NKG2D on CD4CD28(-) and CD4CD28 T-cells, whereas TNF-α and interleukin-15 enhanced NKG2D expression on senescent CD4 and CD8 T-cells only. NKG2D cross-linkage augmented anti-CD3 triggered proliferation, IFN-γ and TNF-α production of CD8 T-cells. In CD4CD28(-) T-cells, NKG2D ligation resulted in increased IFN-γ production only. NKG2D ligands were expressed in temporal arteries from GCA patients, particularly in the adventitial and medial layers of affected vessels.

CONCLUSIONS

NKG2D is functionally expressed on CD4CD28(-) and CD8 T-cells in GCA and PMR. NKG2D-ligands are present in temporal arteries and may co-stimulate NKG2D expressing T-cells.

Association between human papillomavirus DNA and temporal arteritis

Background

To examine the relationship between human papillomavirus (HPV) and giant cell arteritis (GCA) of the temporal artery.

Methods

The study group consisted of 22 cases of histologically positive/biopsy confirmed GCA. The control groups consisted of 21 histologically negative temporal artery biopsies and fifteen cases of vascular margins of nephrectomies. For detection of the presence of HPV, two methods were used: 1) polymerase chain reaction (PCR) with INNO-LiPA HPV Genotyping Extra, 2) Cervista™ HPV HR. All cases were from the files of the Barnes-Jewish Hospital and Washington University in St. Louis.

Results

HPV DNA was detected by PCR and genotyping in 16 of 22 (73%) histologically positive cases of GCA and in only five of 21 (24%) histologically negative temporal artery biopsies. Among the vascular margin controls, only three of 15 (20%) were positive for HPV DNA. The second, independent method (Cervista^TM) confirmed the aforesaid results with 100% concordance with the exception of three cases which had low genomic DNA for which it was not possible to perform the test. The differences in HPV positivity between the histologically positive and negative temporal artery biopsies and between the histologically positive temporal artery biopsies and controls were both statistically significant (p = 0.001 and 0.002, respectively).

Conclusions

The results of our study revealed a statistically significant association between HPV positivity and biopsy confirmed temporal giant cell arteritis GCA (p = 0.001). Further studies are necessary to elucidate the pathophysiology underlying this association.

Synovial xanthomatosis: are there clues to mechanisms for this rare disease?

We report a 64-year-old man with arthritis and nodules to describe that this picture can be caused by normo-lipidemic xanthomas. Light and electron microscopy (EM) plus polymerase chain reaction (PCR) studies were performed for diagnosis and investigation. These showed features typical of xanthomas plus PCR and EM evidence of possible infection with Chlamydia pneumoniae as a pathogenetic mechanism deserving consideration. With such rare diseases, any clues to possible mechanisms seem important to record and thus to encourage future investigations. This uncommon cause of arthritis and nodules had been confused with rheumatoid arthritis by others in this case.

Current understanding and management of giant cell arteritis and polymyalgia rheumatica

Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are linked conditions that occur in the elderly. GCA is a vasculitis of large- and medium-sized vessels causing critical ischemia. It is a medical emergency owing to the high incidence of neuro-ophthalmic complications. PMR is an inflammatory disease characterized by abrupt-onset pain and stiffness of the shoulder and pelvic girdle muscles. Both conditions are associated with a systemic inflammatory response and constitutional symptoms. The pathogeneses are unclear. The initiating step may be the recognition of an infectious agent by activated dendritic cells. The key cell type involved is CD4(+) T cells and the key cytokines are IFN-γ (implicated in granuloma formation) and IL-6 (key to the systemic response). The pathogenesis of PMR may be similar to that of GCA, however, PMR exhibits less clinical vascular involvement. The mainstay of therapy is corticosteroids, and disease-modifying therapy is indicated in relapsing disease. This article reviews recent guidelines on early recognition, investigations and management of these diseases, as well as advances in imaging.

Immunological Aspects of Systemic Vasculitis

Primary vasculitis are commonly multifactorial disorders involving environmental, genetic and immunological factors. Several immune-based effector mechanisms are implicated in the vascular wall damage. These effector mechanisms commonly imply auto-antibodies or immune complexes - mediated cytotoxicity but the contribution of a T-cell mediated immune response has also been described, particularly in large vascular vasculitis. Despite advances in understanding the pathophysiological mechanisms of vasculitis, the triggering events initiating the disease remain largely undefined in most cases. This review highlights the recent advances in the etiopathogenesis of primary vasculitis. A better understanding of the immunological aspects of these disorders may provide insight into the development of novel therapeutical strategies.

Pathogenesis of giant cell arteritis: More than just an inflammatory condition?

Giant cell arteritis (GCA) is characterized by intimal hyperplasia and luminal obstruction leading to ischemic manifestations involving extra-cranial branches of carotid arteries and aorta. Histopathological lesions involve all layers of the arterial wall and are associated with multinucleated giant cells, fragmented internal elastic lamina and polymorphic cellular infiltrates, including T lymphocytes and macrophages. The pathophysiology of GCA is still poorly understood. After dendritic cell activation, CD4(+) T lymphocytes, T helper 1 (Th1) cells, produce interferon gamma and modulate macrophage activation and functions, and Th17 cells produce interleukin 17 (IL-17), which can induce cytokine production by macrophages and fibroblasts. Macrophages in the adventitia produce pro-inflammatory cytokines such as IL-1, IL-6 and tumor necrosis factor alpha. These cytokines promote arterial wall and systemic inflammation. Questions remain regarding the nature of the antigen(s) triggering dendritic cell activation and the mechanisms underlying vascular remodeling. Here we review recent advances in the pathogenesis of GCA, with emphasis on the interactions between cells of the immune system and components of the vessel wall, including vascular smooth muscle cells and endothelial cells, leading to vascular remodeling. Finally, we propose new areas of investigation that could help understand the triggering factors and key pathogenic events in GCA.

[Coxarthrosis--an update]

Degenerative osteoarthritis of the hip joint (coxarthrosis) is the most common disease of the hip joint in adults. The diagnosis is based on a combination of radiographic findings and characteristic clinical symptoms. The lack of a radiographic consensus definition has seemingly resulted in a variation of the published incidences and prevalence of degenerative osteoarthritis of the hip joint. The chronological sequence of degeneration includes the following basic symptoms on conventional radiographs and CT: joint space narrowing, development of osteophytes, subchondral demineralisation/sclerosis and cyst formation, as well as loose bodies, joint malalignment and deformity. MR imaging allows additional visualization of early symptoms and/or activity signs such as cartilage edema, cartilage tears and defects, subchondral bone marrow edema, synovial edema and thickening, joint effusion and muscle atrophy.The scientific dispute concerns the significance of (minimal) joint malalignment (e.g. impingement, dysplasia etc.) and forms of malpositioning which as possible prearthrosis have a high probability of leading to degenerative osteoarthritis. Moreover, without any question, the preservation of joint containment and gender differences are important additional basic diagnostic principles, which have gained great interest in recent years.In research different MR procedures such as Na and H spectroscopy, T2*-mapping etc. with ultrahigh field MR allow cartilage metabolism and its changes in early degenerative osteoarthritis ("biochemical imaging") to be studied. There is no doubt that even in a few years new profound knowledge is to be expected in this field.

No correlation between giant cell arteritis and Chlamydia pneumoniae infection: investigation of 189 patients by standard and improved PCR methods

A total of 189 temporal artery biopsy samples from giant cell arteritis (GCA) patients were investigated using sensitive PCR targeting Chlamydia pneumoniae. Chlamydial DNA was detected in 17 samples, 11 of which were positive for chlamydial antigens. Our data did not reveal strong evidence that C. pneumoniae plays an important role in the pathogenesis of GCA.

Infection and vasculitis

Vasculitis may be associated with infection, immunization or anti-microbial drugs. Infections are responsible for a number of different types of vasculitis. Conversely, patients with vasculitis may develop infections, which sometimes mimic relapse. The aim of this review is to summarize the various aspects of the inter-relationship between vasculitis and infection, and the physiopathological mechanisms involved, in light of our current knowledge from animal models. Currently, a causal relationship between infection and vasculitis has only been established in a few instances and many mechanisms remain hypothetical. This inter-relationship is further assessed from the point of view of clinical presentation and therapeutic options, based on case reports and prospective observational data.

The role of infectious agents in the pathogenesis of vasculitis

Numerous human studies and animal models have implicated various infectious agents in the pathogenesis of vasculitis in susceptible hosts. However, the link between infection and vasculitis is very complex and only incompletely understood. In fact, different agents can induce the same type of vasculitis, as the case of leukocytoclastic vasculitis exemplifies. Conversely, the same agent can give rise to a panoply of host responses ranging from a clinically silent infection or localized organ involvement to devastating, widespread vasculitis.

[Anterior ischemic optic neuropathy: Etiology, pathogenetic mechanisms and therapy]

Ischemic optic neuropathy is caused by ischemia of the optic nerve head in the region of the lamina cribrosa. Differentiation is made between arteritic (AION) and nonarteritic (NAION) forms. AION is the most common ophthalmological manifestation of giant cell arteritis and is usually well controlled with systemic steroid therapy. Temporal artery biopsy for confirmation of the diagnosis is mandatory. NAION is not a disease entity but rather the common pathogenetic pathway of a large variety of diseases and conditions and is often the result of several interacting factors. For this reason, there is no "standard therapy" for NAION. Careful interdisciplinary work up in NAION frequently reveals previously unrecognized diseases requiring treatment according to internal medicine standards. Adequate treatment frequently results in improvement of the affected eye and reduced risk of NAION in the other eye or of brain infarction.

Initial characterization of Chlamydophila (Chlamydia) pneumoniae cultured from the late-onset Alzheimer brain

Previous studies from this laboratory provided evidence that the intracellular bacterial pathogen Chlamydophila (Chlamydia) pneumoniae is present in the late-onset Alzheimer's disease (AD) brain. Here we report culture of the organism from two AD brain samples, each of which originated from a different geographic region of North America. Culturable organisms were detectable after one and two passages in HEp-2 cells for the two samples. Both isolates, designated Tor-1 and Phi-1, were demonstrated to be authentic C. pneumoniae using PCR assays targeting the C. pneumoniae-specific genes Cpn0695, Cpn1046, and tyrP. Assessment of inclusion morphology and quantitation of infectious yields in epithelial (HEp-2), astrocytic (U-87 MG), and microglial (CHME-5) cell lines demonstrated an active, rather than a persistent, growth phenotype for both isolates in all host cell types. Sequencing of the omp1 gene from each isolate, and directly from DNA prepared from several additional AD brain tissue samples PCR-positive for C. pneumoniae, revealed genetically diverse chlamydial populations. Both brain isolates carry several copies of the tyrP gene, a triple copy in Tor-1, and predominantly a triple copy in Phi-1 with a minor population component having a double copy. This observation indicated that the brain isolates are more closely related to respiratory than to vascular/atheroma strains of C. pneumoniae.

Diagnosis and treatment of giant cell arteritis

Giant cell arteritis (GCA) is a chronic granulomatous vasculitis of unknown aetiology occurring in the elderly. It affects the cranial branches of the arteries originating from the aortic arch and is usually associated with markedly elevated acute-phase reactants. In 10-15% of cases the extra-cranial branches of the aortic arch are involved. GCA is closely related to polymyalgia rheumatica (PMR), although the relationship between the two disorders is still unclear. New-onset headache, scalp tenderness, jaw claudication, temporal artery abnormalities on physical examination, visual symptoms and associated PMR represent the most typical and frequent features of the disease. Systemic manifestations, including fever, anorexia and weight loss, are observed in 50% of cases. Less frequent manifestations are related to the central or peripheral nervous systems, the respiratory tract and extra-cranial large-vessel involvement. As GCA is characterized by a wide spectrum of clinical manifestations, it is important to recognize the different onset patterns of the disease and related diagnostic steps. The diagnosis is relatively straightforward in the presence of typical cranial manifestations, but it may be challenging in the case of a normal erythrocyte sedimentation rate, occult GCA or in patients with isolated extra-cranial features. Temporal artery biopsy still represents the gold standard for diagnosis, while the role of ultrasonography, high-resolution magnetic resonance imaging and positron emission tomography should be better addressed. Corticosteroids remain the therapy of choice. Data supporting the usefulness of antiplatelet agents and anticoagulants combined with corticosteroids to prevent ischaemic complications as well as the corticosteroid-sparing effect of methotrexate and anti-tumour necrosis factor-alpha drugs are limited and non-conclusive.

Transmission of Chlamydophila pneumoniae from dendritic cells to macrophages does not require cell-to-cell contact in vitro

Chlamydophila pneumoniae (C. pneumoniae) has been detected in macrophages (Mø) and dendritic cells (DC) in vascular diseases. To understand the importance of these cell types in C. pneumoniae infection and transmission, we infected DC and cultivated them with Mø in a coculture model system which precludes cell-to-cell contact during chlamydial infection. C. pneumoniae inside living DC were labeled and tracked with a red fluorescent ceramide dye. Subsequently, red-coloured chlamydial inclusions were detected 3 and 5 days later in cocultured Mø. Moreover, standard assays revealed infectious elementary bodies in infected DC and cocultured Mø. Assays for chlamydial gene expression indicated vital and dividing chlamydiae in both cell types. In summary, the results suggest that the transwell system employed here is a suitable model to investigate the transmission of C. pneumoniae from DC to Mø. Importantly, the observations presented demonstrate that transmission is independent of cell-to-cell contact.

Apolipoprotein E4 enhances attachment of Chlamydophila (Chlamydia) pneumoniae elementary bodies to host cells

Chlamydophila (Chlamydia) pneumoniae is an intracellular respiratory pathogen known to cause community-acquired pneumonia. Infection with this organism has been associated with atherosclerosis, inflammatory arthritis, and other chronic diseases, many of which also have been associated with possession of the epsilon4 allele at the APOE locus on (human) chromosome 19. An earlier study from this laboratory suggested that some relationship exists between apolipoprotein E4 (apoE4), the product of the epsilon4 allele, and the pathobiology of C. pneumoniae. A standard attachment assay and real time PCR targeting a sequence on the C. pneumoniae chromosome were used to monitor host cell binding of elementary bodies (EB) of that organism. Our data indicate that 3-fold more EB of strain AR-39 attach to an epsilon3 homozygous human cell line transfected with a plasmid expressing the epsilon4 coding sequence than to the same cell line harboring empty vector, vector containing an irrelevant insert sequence, or vector containing the DNA sequence encoding apoE3. The quantitative real time data were confirmed by immunolabeling of chlamydial inclusions in parallel attachment and infection assays. Experiments using Chlamydophila trachomatis EB showed no enhancement of attachment in the presence of the epsilon4 allele in any assays. These observations indicate that apoE4 enhances attachment of C. pneumoniae EB, but not those of C. trachomatis, to target host cells.

Host cell responses to Chlamydia pneumoniae in gamma interferon-induced persistence overlap those of productive infection and are linked to genes involved in apoptosis, cell cycle, and metabolism

The respiratory pathogen Chlamydia (Chlamydophila) pneumoniae is associated with chronic diseases, including atherosclerosis and giant-cell arteritis, which are accompanied by the occurrence of these obligate intracellular bacteria in blood vessels. There, C. pneumoniae seems to be present in a persistent state. Persistence is characterized by modified bacterial metabolism and morphology, as well as a reversible arrest of chlamydial development. In cell culture, this persistent state can be induced by gamma interferon (IFN-gamma). To elucidate this long-term interaction between chlamydiae and their host cells, microarray screening on epithelial HeLa cells was performed. Transcription of persistently (and productively) infected cells was compared with that of mock-infected cells. Sixty-six host cell genes were regulated at 24 h and/or 96 h of IFN-gamma-induced persistence. Subsequently, a set of 17 human host cell genes related to apoptosis, cell cycle, or metabolism was identified as permanently up- or down-regulated by real-time PCR. Some of these chlamydia-dependent host cell responses were diminished or even absent in the presence of rifampin. However, other expression patterns were not altered by the inhibition of bacterial RNA polymerase, suggesting two different modes of host cell activation. Thus, in the IFN-gamma model, the persisting bacteria cause long-lasting changes in the expression of genes coding for functionally important proteins. They might be potential drug targets for the treatment of persistent C. pneumoniae infections.

Diagnosis, differential diagnosis and treatment of polymyalgia rheumatica

Polymyalgia rheumatica (PMR) is a common disorder in the elderly population. The diagnosis is based upon recognition of a clinical syndrome, consisting of pain and stiffness in the shoulder and pelvic girdle, muscle tenderness of the upper and lower limbs and nonspecific somatic complaints. In addition, in most cases the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) concentration are highly elevated. Although PMR and giant cell arteritis (GCA) are commonly regarded as two clinical variations of the same disease, their clinical picture is quite different. Whilst in PMR the musculoskeletal symptoms predominate, the major features of GCA are arterial inflammation and its consequences, which suggests clinical and pathological discrepancies between the two syndromes and important differences with respect to morbidity and mortality. The prognosis of correctly diagnosed PMR is excellent. It is well known that corticosteroid therapy in PMR usually leads to rapid and dramatic improvement of patients' complaints and returns them to previous functional status. However, prolonged corticosteroid treatment, sometimes for several years, may be necessary to maintain clinical improvement. Despite all the knowledge about the beneficial effects of corticosteroid treatment, data concerning the optimal dosage regimen are lacking. Long-term corticosteroid use can be associated with various adverse events, of which induction of osteoporosis, diabetes mellitus and infection among the worst. A Corticosteroid Side Effect Questionnaire has been shown to dose-dependently detect adverse effects perceived by patients. The European League Against Rheumatism (EULAR) response criteria for PMR comprise a core set of markers for monitoring therapeutic responses in PMR, namely ESR or CRP, the visual analogue scale of patient's pain and physician's global assessment, as well as morning stiffness and the ability to elevate the upper limbs. The PMR-disease activity score has been developed on the basis of EULAR response criteria as a means of expressing disease activity as an absolute number. A score <7 indicates low disease activity, scores 7-17 suggest medium activity, and a score >17 is indicative of high disease activity. The PMR-disease activity score has been proven to be highly correlated with patient's global assessment, patient satisfaction and ESR. It provides an easily applicable and valid tool for disease activity monitoring in patients with PMR. Improved knowledge of disease activity processes, exact monitoring of disease activity and treatment responses, and increased risk-estimation of treatment schedules should ultimately improve the care of patients with PMR.

Giant cell arteritis

Giant cell, or temporal, arteritis is a vasculitis of the medium and large arteries that preferentially involves vessels originating from the arch of the aorta. Classically, this disease manifests in an older individual with new-onset persistent headache, an abnormal temporal artery on examination, and increased serum inflammatory markers. The level of clinical suspicion for giant cell arteritis should be based upon patient age, clinical symptoms, and laboratory evaluation. However, the diagnostic gold standard is achieved by histologic confirmation by temporal artery biopsy. Prompt treatment with corticosteroids is essential in order to minimize the frequency of permanent sequelae such as visual loss and stroke.

[Giant cell arteritis (temporal arteritis). Pathophysiology, immunology]

The diagnosis of giant cell arteritis is established by temporal artery biopsy. The findings are those of a panarteritis with mononuclear infiltrates penetrating all layers of the arterial wall. Typically, activated T cells and macrophages are arranged in granulomas. Multinucleated giant cells, when present, are usually close to the fragmented internal elastic lamina. Often, the intimal layer is hyperplastic, leading to concentric occlusion of the lumen. The CD4(+) T cells are the main players in the disease process. T-cell activation in the arterial wall requires the presence of specialized antigen-presenting cells, the dendritic cells. The activation of monocytes and macrophages is responsible for the systemic inflammatory syndrome in giant cell arteritis and polymyalgia rheumatica. The blood vessel wall determines the site specificity of giant cell arteritis and provides the ground for the cell to cell interaction.

Failure to detect human herpes simplex virus, cytomegalovirus, and Epstein–Barr virus viral genomes in giant cell arteritis biopsy specimens by real-time quantitative polymerase chain reaction

A study provided evidence of human herpes simplex virus (HSV) DNA in giant cell arteritis (GCA) biopsy specimens. This prompted us to study our own GCA biopsy specimens using real-time quantitative polymerase chain reaction for the detection of HSV1, cytomegalovirus, and Epstein-Barr virus DNAs. Our study failed to confirm an association between HSV1 and GCA, revealing no viral genome in 35 biopsy specimens of histologically positive temporal arteries.