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

Association between infection and the onset of giant cell arteritis and polymyalgia rheumatica: a systematic review and meta-analysis

OBJECTIVE

We aimed to analyse the association between infections and the subsequent risk of giant cell arteritis (GCA) and/or polymyalgia rheumatica (PMR) by a systematic review and a meta-analysis of observational studies.

METHODS

Two databases (Medline and Embase) were systematically reviewed. Epidemiological studies studying the association between any prior infection and the onset of GCA/PMR were eligible. Risk of bias was assessed using the Newcastle-Ottawa quality assessment scale. Outcomes and pooled statistics were reported as OR and their 95% CI.

RESULTS

Eleven studies (10 case-control studies and one cohort study) were analysed, seven of them were included in the meta-analysis. Eight were at low risk of bias. A positive and significant association was found between prior overall infections and prior Herpes Zoster (HZ) infections with pooled OR (95% CI) of 1.27 (1.18 to 1.37) and 1.20 (1.08 to 1.21), respectively. When analysed separately, hospital-treated and community-treated infections, were still significantly associated with the risk of GCA, but only when infections occurring within the year prior to diagnosis were considered (pooled OR (95% CI) 1.92 (1.67 to 2.21); 1.67 (1.54 to 1.82), respectively). This association was no longer found when infections occurring within the year prior to diagnosis were excluded.

CONCLUSION

Our study showed a positive association between the risk of GCA and prior overall infections (occurring in the year before), and prior HZ infections. Infections might be the reflect of an altered immunity of GCA patients or trigger the disease. However, reverse causation cannot be excluded.CRD42023404089.

Environmental Triggers for Vasculitis

Systemic vasculitides are autoimmune diseases characterized by vascular inflammation. Most types of vasculitis are thought to result from antigen exposure in genetically susceptible individuals, suggesting a likely role for environmental triggers in these conditions. Seasonal and geographic variations in incidence provide insight into the potential role of environmental exposures in these diseases. Many data support infectious triggers in some vasculitides, whereas other studies have identified noninfectious triggers, such as airborne pollutants, silica, smoking, and heavy metals. We review the known and suspected environmental triggers in giant cell arteritis, Takayasu arteritis, polyarteritis nodosa, Kawasaki disease, and antineutrophil cytoplasmic antibody-associated vasculitis.

Highlights in clinical medicine-Giant cell arteritis, polymyalgia rheumatica and Takayasu's arteritis: pathogenic links and therapeutic implications

Giant cell arteritis (GCA), frequently associated with polymyalgia rheumatica (PMR), and Takayasu's arteritis (TAK) are characterized by extensive vascular remodeling that results in occlusion and stenosis. The pathophysiological mechanisms underlying the onset of GCA/PMR and TAK are still hypothetical. However, similarities and differences in the immunopathology and clinical phenotypes of these diseases point toward a possible link between them. The loss of tolerance in the periphery, a breakdown of tissue barriers, and the development of granulomatous vasculitis define a disease continuum. However, statistically powered studies are needed to confirm these correlations. In addition to glucocorticoids, inhibition of the interleukin-6 axis has been proposed as a cornerstone in the treatment of GCA/PMR and TAK. Novel biologic agents targeting the pathogenic pathway at various levels hold promise to achieve glucocorticoid-free sustained remission.

[Pathogenesis of large vessel vasculitides]

Large vessel vasculitides comprise two distinct entities, giant cell arteritis (GCA) and Takayasu arteritis (TAK). GCA is the most common vasculitis in central Europe, becoming manifested at an age over 50 years. In contrast, the much rarer TAK affects almost exclusively young adults and mostly women. Both vasculitides are granulomatous arteritides affecting mainly the aorta and its major arterial branches. GCA and TAK are associated with different major histocompatibility complex genes. Infections possibly play a role in the initiation of large vessel vasculitides. Activation of dendritic cells in the adventitia induces chemokine and cytokine-mediated recruitment and maturation of T‑helper (Th)1 and Th17 cells and macrophages producing cytokines, growth factors and matrix metalloproteinases. In GCA, CD4+ T‑helper cells and macrophages are predominantly found in the inflammatory infiltrate. In TAK, the infiltrate also contains cytotoxic CD8+ T‑cells and γδ T‑cells. This could indicate different antigenic triggers in GCA and TAK. Inflammatory infiltration with T‑cells and macrophages and activation of myofibroblasts and smooth muscular cells induce vascular remodeling with intimal hyperplasia and destruction of the media. Remodeling is histologically characterized by progressive arterial wall fibrosis, vascular stenosis and obstruction. In summary, GCA and TAK represent two different entities with a distinct human leukocyte antigen (HLA) and potentially etiopathogenetic background. Clinically, inflammation-related general symptoms and signs of ischemia are encountered, accompanied by increased levels of serological markers of inflammation.

[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.

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.

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.

Infectious triggers for vasculitis

PURPOSE OF REVIEW

Infections have been suggested to contribute to disease induction and reactivation in many of the idiopathic vasculitides. This review describes and evaluates the evidence that microbes are involved in the etiopathogenesis of these diseases.

RECENT FINDINGS

Large-vessel vasculitis has recently been associated with two specific bacteria. Mycobacterium tuberculosis is thought to have an inducing role in Takayasu arteritis and a Burkholderia bacterium might be involved in giant cell arteritis. Hepatitis B and C viruses have been linked to polyarteritis nodosa. In antineutrophil cytoplasmic autoantibody-associated vasculitis, and more specifically granulomatosis with polyangiitis (GPA), Staphylococcus aureus has been the focus of many studies. Chronic nasal carriage of S. aureus is related to endonasal activity and disease relapses in GPA patients. Moreover, antibacterial treatment is known to reduce the risk for disease relapses. If and how pathogens trigger vasculitis is still unclear, but several potential mechanisms have been suggested and are briefly reviewed here.

SUMMARY

Although many observations suggest a link between infections and the development of vasculitis, no direct proof exists. Transcriptomic and proteomic studies of the pathogens involved could aid in identifying specific or common traits of pathogens that are relevant for the development and reactivation of vasculitis.

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.

Ophthalmic manifestations of giant cell arteritis

This article reviews the ophthalmic manifestations of giant cell arteritis. An overview of giant cell arteritis as a disease spectrum is presented with special emphasis on the ophthalmic involvement.

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.