Perforin-secreting killer cell infiltration and expression of a 65-kD heat-shock protein in aortic tissue of patients with Takayasu's arteritis

JAK inhibitors (JAKi): Mechanisms of action and perspectives in systemic and autoimmune diseases

Janus kinase (JAK) molecules are involved in important cellular activation pathways. Over the past decade, many targeted therapies have emerged, including the increasingly promising role of JAK inhibitors (JAKi) in the treatment of inflammatory and autoimmune diseases. The spectrum of use of these small molecules is increasingly broader. JAKi have been approved in several autoimmune diseases. Currently, four molecules (tofacitinib, baricitinib, upadacitinib and filgotinib) have been labeled for moderate to severe rheumatoid arthritis (RA) with failure or poor tolerance of one or more conventional disease-modifying antirheumatic drug (csDMARDS), or biologics (bDMARDS). JAKi are now also commonly used in other diseases such as psoriatic arthritis, ankylosing spondylitis, and ulcerative colitis. They have also shown promising results in clinical trials for the treatment of other autoimmune conditions. We present here their mechanisms of action, and the main data about JAKi use on systemic and autoimmune diseases.

Mechanisms and Screening for Atherosclerosis in Adults With Vasculitis

Vascular inflammation is a hallmark of both primary systemic vasculitis and atherosclerosis. As such, cardiovascular events are common in patients with vasculitis and likely due to both direct vascular inflammation and accelerated atherosclerosis. Direct cardiac involvement is possible in all vasculitides, though more commonly described in Takayasu arteritis, polyarteritis nodosa, and eosinophilic granulomatosis with polyangiitis. Accelerated atherosclerosis has been described in Takayasu arteritis and antineutrophil cytoplasmic antibody-associated vasculitis, though there remains a paucity of data in other forms of vasculitis. Multiple screening and management approaches for cardiovascular risk in people with vasculitis have been proposed, though evidence-based guidelines are lacking. In this review, we discuss the latest evidence in epidemiology, mechanisms, and screening for atherosclerosis in patients with primary systemic vasculitides.

Amaurosis fugax in Takayasu arteritis mimicking migraine with visual aura

Takayasu arteritis is a rare vasculitis commonly seen in young women. Amaurosis fugax and headache are visual presentations of Takayasu arteritis. Migraine with visual aura is a common condition affecting young women, and differentiating migraine from Takayasu presenting with visual symptoms and headache can be challenging. We present a case of a young woman initially misdiagnosed with migraine with aura, who was later found to have amaurosis fugax as an early manifestation of Takayasu arteritis.

Exploring the causal relationship between Takayasu arteritis and inflammatory bowel disease using Mendelian randomization

Takayasu arteritis (TA) and inflammatory bowel disease (IBD) are two distinct diseases; however, previous studies have reported many cases of IBD-TA coexistence. Additionally, the incidence of IBD in patients with TA is estimated to be significantly higher than the incidence in the general population. Therefore, the two diseases are anticipated to be linked. Mendelian randomization (MR) analysis assesses whether an exposure might causally affect an outcome by using genetic variants inherited randomly at conception, thereby reducing the impact of confounding and reverse causality. The present study aimed to investigate the potential causal relationship between TA and IBD using MR analysis. Two-sample MR analysis, in which TA and IBD were regarded as the exposure and outcome, respectively, was conducted to investigate whether the two diseases are causally related using the R TwoSampleMR package. Summary GWAS data of TA consisted of 516 Turkish cohorts and 462 controls, and 119 patients and 993 controls of European ancestry. Summary data of IBD was from a sub-study of the International Inflammatory Bowel Disease Genetics Consortium (IIBDGC) that comprised 31,665 cases and 33,977 controls of European ancestry. Additionally, separate MR analyses stratified by the two major subtypes of IBD, Crohn's disease (CD) and ulcerative colitis (UC), were performed. Various statistical tests, including the intercept of MR-Egger regression, funnel plots, Cochran's Q tests, and leave-one-out sensitivity analyses, were employed to assess the presence of heterogeneity and horizontal pleiotropy among single nucleotide polymorphisms (SNPs). In the primary analysis using the inverse-variance weighted (IVW) method, the risk of developing IBD for a patient with TA compared to a non-TA control increased 1.053 times (Odds Ratio (OR) = 1.053, P = 0.065). The MR-Egger method (OR = 1.025, P = 0.470) yielded results consistent with this null finding. However, both the weighted median method (OR = 1.038, P = 0.002) and the weighted mode method (OR = 1.051, P = 0.009) identified a significant harmful causal effect. The MR outcomes from separate subgroup analyses slightly diverged from those of IBD and TA. Specifically, for CD, three methods indicated that TA is a risk factor: IVW estimated the OR as 1.045 (P = 0.032), MR-Egger as 0.997 (P = 0.957), weighed median as 1.028 (P = 0.021), and weighted mode as 1.031 (P = 0.022), respectively. This study represents one of the initial investigations into the potential causal association between TA and IBD. With three MR methods, including the primary IVW approach, indicating a notable effect on TA on CD, our analysis findings offer some indication that TA could be a contributing risk factor for CD.

Posterior segment manifestations of Takayasu arteritis: A narrative review

Ocular symptoms can be the presenting manifestation of Takayasu arteritis (TA) or could be indicative of disease reactivation. A review of published literature related to posterior segment manifestations of TA by using the keywords "Takayasu arteritis," "ophthalmic manifestations," "retina," "retinopathy," "ocular," "optic nerve," and "optic neuropathy" was performed. In total, 62 case reports and 12 case series were included. The majority of the articles were from Asia (n = 47, 64%). Females outnumbered males in the ratio of 7:1. The mean age of patients was 33 years (range: 8-78 years, SD: 13.5 years). In 58% (n = 41 out of 71) cases, ocular symptoms were the presenting manifestation of the underlying disease. Hypotensive retinopathy was found in 70% of eyes, and hypertensive retinopathy was found in 27%. The mean presenting visual acuity (VA) was +1.03 logMAR (range: -0.12 to 3, SD: 1.07), and at the final follow-up was +1.02 logMAR (range: -0.12 to 3, SD 1.17). VA improved in 34% (n = 29/86), remained stable in 45% (39/86), and worsened in 21% (18/86). The mean follow-up was 9 months (range: 0.5-204, SD: 16 months).

Multi-Modality Imaging in Vasculitis

Systemic vasculitides are a rare and complex group of diseases that can affect multiple organ systems. Clinically, presentation may be vague and non-specific and as such, diagnosis and subsequent management are challenging. These entities are typically classified by the size of vessel involved, including large-vessel vasculitis (giant cell arteritis, Takayasu's arteritis, and clinically isolated aortitis), medium-vessel vasculitis (including polyarteritis nodosa and Kawasaki disease), and small-vessel vasculitis (granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis). There are also other systemic vasculitides that do not fit in to these categories, such as Behcet's disease, Cogan syndrome, and IgG4-related disease. Advances in medical imaging modalities have revolutionized the approach to diagnosis of these diseases. Specifically, color Doppler ultrasound, computed tomography and angiography, magnetic resonance imaging, positron emission tomography, or invasive catheterization as indicated have become fundamental in the work up of any patient with suspected systemic or localized vasculitis. This review presents the key diagnostic imaging modalities and their clinical utility in the evaluation of systemic vasculitis.

Prevalence of tuberculosis infection among patients with Takayasu arteritis: a meta-analysis of observational studies

To clarify the risk of tuberculosis (TB) infection in patients with Takayasu arteritis (TAK). In this study, we conducted a comprehensive search across multiple databases, including PubMed, Web of Science, Embase, Cochrane, and Medline, from the inception of the Literature Library to May 16, 2023. Using a specific set of keywords, including "Takayasu Arteritis", "Tuberculosis", and "Mycobacterium tuberculosis", the main objective of this search was to identify all relevant observational studies, including case-control studies, cohort studies, and cross-sectional studies, that report the prevalence of TB in individuals diagnosed with TAK. Two independent evaluators rigorously screened the studies, extracted data, and assessed the study quality using the Joanna Briggs Institute (JBI) critical appraisal tools. Statistical analyses were conducted using R software version 4.3.0, which allowed for the synthesis of prevalence and subgroup analyses. Subgroup analyses were stratified based on quality scores, World Health Organization regional categorizations, and TB categories. Assessment of publication bias was performed using a funnel plot. The study included a total of 30 studies with 5548 participants. The findings showed that individuals with TAK exhibited an average prevalence of TB infection at 31.27% (95% CI 20.48-43.11%). Significantly, the prevalence of TB infection demonstrated notable regional disparities, ranging from 16.93% (95% CI 7.71-28.76%) in the Western Pacific Region to 63.58% (95% CI 35.70-87.66%) in the African Region. Moreover, the study revealed that patients with TAK displayed a high prevalence of latent TB infection (LTBI) at 50.01% (95% CI 31.25-68.77%) and active TB at 14.40% (95% CI 9.03-20.68%). The high heterogeneity observed in the data highlights significant variability in TB infection rates among the populations studied, with the African Region exhibiting the highest rates. The study concludes that there is a high prevalence of TB infection in the TAK population, with regional variations. Consideration should be given to  implementing rigorous TB screening measures and preventive interventions specifically tailored for the TAK population.

Common Autoantibody among Takayasu Arteritis and Ulcerative Colitis: A Possible Pathophysiology That Includes Gut-Vessel Connection in Vascular Inflammation

Takayasu arteritis (TAK) is a type of large-vessel vasculitis that predominantly affects young females. The precise pathomechanism of TAK is still under investigation. In TAK, the vasa vasorum is considered to be the initial inflammatory site. Disruption of the vasa vasorum induces the entry of inflammatory cells into the vascular wall of large vessels between the media and adventitia, and infiltrated cells damage the vascular components, eventually leading to stenosis or dilatation of the affected arteries. In addition, T cells are considered key players in TAK, and myeloid cells function as effector cells. Although the roles of B cells in TAK are poorly understood, recent evidence supports their contribution to the pathogenicity of TAK. Particularly, two autoantibodies have been identified in TAK through investigation of anti-endothelial cell antibodies, and they could be involved in the maintenance of vascular inflammation. Furthermore, one of the autoantibodies, anti-endothelial protein C receptor, was shown to be present in ulcerative colitis (UC), which is genetically and clinically associated with TAK. Similar autoantibodies in inflammatory diseases with different target organs indicate a common underlying pathophysiology of these diseases, which could be characterized by the aberrant activation of B cells. This review discusses recent understanding of the pathomechanisms of TAK and UC, with a focus on the involvement of B cells and autoantibodies. The close association of UC with TAK further suggests a common etiology, and the importance of the intestinal microbiota, including dysbiosis, is also becoming known in TAK. Investigation of such common factors among TAK and UC would improve understanding of the interplay between gut and vascular inflammation, which is a new concept for developing vascular inflammation through the gut-vessel connection.

Left ventricular strain in patients with Takayasu arteritis with preserved ejection fraction: an analysis using cardiac magnetic resonance imaging feature tracking

Background

The alteration of myocardial strain in patients with Takayasu arteritis (TAK) remains unclear. This study aimed to evaluate left ventricular (LV) stain in patients with TAK and preserved left ventricular ejection fraction (pLVEF) using cardiac magnetic resonance imaging feature tracking (CMR-FT) to analyze risk factors for impaired LV strain and to compare the baseline difference of LV strain between patients with reduced and nonreduced LVEF at 6-month follow-up.

Methods

In all, 51 patients with TAK and 30 healthy controls were prospectively enrolled. All participants underwent multiple short- and long-axis cine scans with true fast imaging with steady-state precession sequence. In this observational study, LV global and regional longitudinal, circumferential, and radial strain and their strain rates were analyzed with FT on cine images. The relationship between LV strain and clinical data was explored. The baseline LV strain between patients with TAK and reduced and nonreduced LVEF was compared using transthoracic echocardiography (TTE) at the 6-month follow-up.

Results

Patients with TAK with pLVEF showed a decline in baseline global longitudinal peak strain (GLS) [TAK (-13.35%±3.11%) vs. controls (-14.77%±1.74%), P=0.021] and circumferential peak strain (GCS) [TAK (-21.46%±2.66%) vs. controls (-22.75%±2.57%), P=0.027] in comparison with normal controls. The longitudinal peak strain (LPS) in the apical (P=0.003) and midventricular regions (P=0.027) and the circumferential peak strain (CPS) in the basal (P=0.021) and midventricular regions (P=0.008) also decreased in patients with TAK. Patients with pulmonary hypertension (PH) or myocardial late gadolinium enhancement (LGE) showed a greater reduction in strain compared with those without PH or LGE. GLS showed a negative association with erythrocyte sedimentation rate (ESR), while GCS showed a positive association with disease duration. In the 30 patients who were followed up, the baseline global and apical circumferential diastolic peak strain rates (DPSR) in patients with reduced LVEF were higher than those in patients without reduced LVEF.

Conclusions

In patients with TAK and pLVEF, CMR-FT indicated that both global and segmental myocardial strain decreased. PH, male gender, long disease duration, elevated ESR, and myocardial LGE were associated with declined LV strain. Baseline increased circumferential DPSR may be associated with the decline in LVEF during follow-up.

Predictors for pulmonary artery involvement in Takayasu arteritis and its cluster analysis

OBJECTIVE

To investigate the clinical characteristics and the site of pulmonary involvement in Takayasu arteritis (TAK) patients with pulmonary artery involvement (PAI).

METHODS

We retrospectively investigated data of 141 TAK patients. The clinical and image data of the patients with and without PAI were analyzed and compared. The patients were followed up. The major outcome was all-cause mortality. The minor outcome was exacerbation or new occurrence of PAI, which leads to disease progression events.

RESULTS

For the 141 TAK patients considered, PAI was detected in 65 (46.1%) patients. TAK patients with PAI had a significantly higher cumulative incidence of events than those without PAI (P < 0.001). The frequencies of the following were significantly higher in TAK with PAI than those in TAK without PAI: disease duration [median 96 months (IQR: 24-174) vs. median 42 months (IQR: 6-120); P = 0.012], hemoptysis (10.8% vs. 1.32%; P = 0.040), oppression in the chest (40.0% vs. 21.1%; P = 0.014), fever (23.1% vs. 9.21%; P = 0.024), Mycobacterium tuberculosis infection (21.5% vs. 6.57%; P = 0.010), pulmonary hypertension (PAH) (21.5% vs. 2.6%; P < 0.001), pulmonary infarction (41.5% vs. 0%; P < 0.001), and hypoxemia (18.5% vs. 1.3%; P < 0.001). Multivariate logistic regression analysis of data of TAK patients with symptom presentation showed that oppression in the chest (OR: 2.304; 95% CI: 1.024-5.183; P = 0.044) and thoracic aorta involvement (OR: 2.819; 95% CI: 1.165-6.833; P = 0.022) were associated with PAI. The cluster analysis performed for data of TAK patients with PAI revealed that the cluster characterized as the upper lobe of the right lung (Cluster1) had the worst prognosis.

CONCLUSION

In TAK, PAI is associated with thoracic aorta involvement. In TAK patients with PAI, the involvement of the upper lobe of the right lung is characterized with the worst prognosis.

Clinical study of carotid superb microvascular imaging in evaluating the activity of Takayasu's arteritis

Objective

The goal of this study is to use superb microvascular imaging (SMI) to observe neovascularization in the carotid vessel wall to identify potential Takayasu's arteritis (TAK) inflammation markers.

Methods

Bilateral carotid arteries from 96 patients with TAK were imaged by a Doppler ultrasound and SMI. The one-way analysis of variance (ANOVA) was used to document significant differences between the activity and inactivity stages of TAK and the factors closely related to its activity in the binary logistics regression equation. Clinical and laboratory data included age, gender, duration of disease, treatment history, NIH score, erythrocyte sedimentation rate (ESR), and high-sensitivity C-reactive protein. Imaging data included the arterial wall thickness, degree of lesion, SMI grade, and arterial aneurysm formation.

Results

There were 45 patients in the active TAK stage and 51 in the inactive stage. The one-way ANOVA showed significant differences in SMI (p = 0.001) and ESR (p = 0.022) between the active and inactive groups. The binary logistics regression analysis showed that SMI was an independent risk factor for TAK activity (B = -1.505, S.E = 0.340, Wald = 19.528, OR = 0.222 95%, CI = 0.114-0.433, p < 0.01). Using SMI G1 or G2 as the cutoff values for the diagnosis of active TAK, the positive predictive value, sensitivity, and specificity were 60 and 86%, 84% and 56%, and 54% and 92%, respectively.

Conclusion

The SMI grade is a potential marker of disease activity in patients with TAK.

Advances in Takayasu arteritis: An Asia Pacific perspective

Takayasu Arteritis (TA) is a rare form of chronic granulomatous large vessel vasculitis that is more common in Asia compared to other parts of the world. There have been several developments in the field of Takayasu arteritis in relation to genetics, classification, clinical features, imaging, disease activity assessment and management and much of these works have been done in the Asia Pacific region. We will be discussing selected few in the current review.

Longitudinal monitoring of circulating immune cell phenotypes in large vessel vasculitis

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are two types of primary large vessel vasculitis (LVV). LVV is an intractable, rare disease with a high relapse rate. Disease progression in asymptomatic patients is an important issue in the clinical management of LVV. Useful biomarkers associated with clinical phenotypes, disease activity, and prognosis may be present in peripheral blood. In this review, we focused on peripheral leukocyte counts, surface markers, functions, and gene expression in LVV patients. In particular, we explored longitudinal changes in circulating immune cell phenotypes during the active phase of the disease and during treatment. The numbers and phenotypes of leukocytes in the peripheral blood were different between LVV and healthy controls, GCA and TAK, LVV in active versus treatment phases, and LVV in treatment responders versus non-responders. Therefore, biomarkers obtained from peripheral blood immune cells may be useful for longitudinal monitoring of disease activity in LVV.

Inflammatory Thoracic Aortic Aneurysm in a Patient with Advanced Lung Adenocarcinoma Treated with Pembrolizumab

A 57-year-old man with lung adenocarcinoma was treated with chemotherapy and immune checkpoint blockade. After two cycles of carboplatin, pemetrexed, and pembrolizumab, he developed a persistent fever. Chest computed tomography (CT) suggested inflammation of the aortic wall. We treated the patient with corticosteroids. After four cycles of carboplatin, pemetrexed, and pembrolizumab, chest CT showed an aneurysm in the ascending aorta. We diagnosed him with inflammatory thoracic aortic aneurysm induced by pembrolizumab and performed surgical replacement of the ascending aorta. Although this might be a very rare case, we should be aware of aortitis as a potential adverse effect of pembrolizumab.

Childhood-onset Takayasu arteritis and immunodeficiency: case-based review

Takayasu arteritis (TAK) has been rarely reported in patients with immunodeficiency. In this review, we present two cases with childhood-onset TAK (c-TAK) and primary immunodeficiency while reviewing similar cases in the literature. We reviewed the data for our two pediatric patients with c-TAK and primary immunodeficiency. We also reviewed the literature for patients with c-TAK and immunodeficiency from the inceptions of the databases up to November 2021. A 14-year-old patient had lipopolysaccharide-sensitive beige-like anchor (LRBA) deficiency, and a 16-year-old had X-linked severe combined immunodeficiency (X-linked SCID). During the follow-up, they developed findings suggestive of vasculitides such as hypertension, elevation in acute phase reactants, weakness, and weight loss. Thoracoabdominal computed tomography angiography revealed findings consistent with vasculitis involving the aorta and its major branches. Patients were diagnosed with c-TAK, and corticosteroids were given to both patients in the treatment. We identified 11 articles describing 17 TAK patients with immunodeficiency in our literature search. Two of the patients with c-TAK were infected with human immunodeficiency virus (HIV), another patient had Wiskott-Aldrich syndrome, and the other had idiopathic CD4 + T lymphocytopenia. Nine adult patients with TAK were infected with HIV, three patients had common variable immunodeficiency disorder (CVID), and the other had STAT1 gain-of-function mutation. Clinicians should consider that immunodeficiencies may be accompanied by vasculitic conditions such as TAK. Hypertension, increased inflammatory markers, and constitutional symptoms may be red flags for the development of TAK.

Genome-Wide DNA Methylation Profiling in CD8 T-Cells and Gamma Delta T-Cells of Asian Indian Patients With Takayasu Arteritis

Background: Takayasu’s Arteritis (TA) is a chronic inflammatory disease that affects aorta and its main branches at their origin. Genetic, pathological and functional studies have shown that CD8 and Gamma delta (γ/δ) T-lymphocytes are involved in inflammatory processes in affected regions of arteries causing vascular damage. The molecular function of these lymphocytes remains unclear and currently no epigenetic studies are available in TA. We primarily performed genome wide methylation analysis in CD8 T cells and γδ T cells of patients with TA and compared with healthy controls.

Methods: We recruited 12 subjects in each group namely TA patient and healthy controls. Blood samples were collected after obtaining informed written consent. CD8 T cells and γδ T cells were separated from whole blood. DNA extracted from these cells and were subjected to bisulfite treatment. Finally, bisulfite treated DNA was loaded in Infinium Methylation EPIC array. Bioinformatics analysis was used to identify differential methylation regions which were then mapped to genes.

Results: Interleukin (IL)-32 and Lymphotoxin-A were genes significantly hypomethylated in CD8 T-cells. Anti-inflammatory cytokine genes, IL-10, IL-1RN and IL-27 were hypomethylated in γδ T cells of TA patients as compared to healthy controls. Gene enrichment analysis using Gene Ontology (GO) database and Kyoto Encyclopaedia of Genes and Genomes (KEGG) identified that genes involved in T-cell receptor signalling pathways were hypomethylated in CD8 T-cells and hypermethylated in γδ T cells of TA patients.

Conclusion: CD8 T-cells might play a major role in immunopathogenesis of inflammation in TA, whereas γδ T cells may play a regulatory role.

Vasculitogenic T Cells in Large Vessel Vasculitis

Vasculitis is an autoimmune disease of unknown etiology that causes inflammation of the blood vessels. Large vessel vasculitis is classified as either giant cell arteritis (GCA), which occurs exclusively in the elderly, or Takayasu arteritis (TAK), which mainly affects young women. Various cell types are involved in the pathogenesis of large vessel vasculitis. Among these, dendritic cells located between the adventitia and the media initiate the inflammatory cascade as antigen-presenting cells, followed by activation of macrophages and T cells contributing to vessel wall destruction. In both diseases, naive CD4⁺ T cells are polarized to differentiate into Th1 or Th17 cells, whereas differentiation into regulatory T cells, which suppress vascular inflammation, is inhibited. Skewed T cell differentiation is the result of aberrant intracellular signaling, such as the mechanistic target of rapamycin (mTOR) or the Janus kinase signal transducer and activator of transcription (JAK-STAT) pathways. It has also become clear that tissue niches in the vasculature fuel activated T cells and maintain tissue-resident memory T cells. In this review, we outline the most recent understanding of the pathophysiology of large vessel vasculitis. Then, we provide a summary of skewed T cell differentiation in the vasculature and peripheral blood. Finally, new therapeutic strategies for correcting skewed T cell differentiation as well as aberrant intracellular signaling are discussed.

Phenotypic, transcriptomic and functional profiling reveal reduced activation thresholds of CD8+ T cells in giant cell arteritis

OBJECTIVES

Evidence from temporal artery tissue and blood suggests involvement of CD8+ T cells in the pathogenesis of GCA, but their exact role is poorly understood. Therefore, we performed a comprehensive analysis of circulating and lesional CD8+ T cells in GCA patients.

METHODS

Circulating CD8+ T cells were analysed for differentiation status (CD45RO, CCR7), markers of activation (CD69 and CD25) and proliferation (Ki-67) in 14 newly diagnosed GCA patients and 18 healthy controls by flow cytometry. Proliferative capacity of CD8+ T cells upon anti-CD3 and anti-CD3/28 in vitro stimulation was assessed. Single-cell RNA sequencing of peripheral blood mononuclear cells of patients and controls (n = 3 each) was performed for mechanistic insight. Immunohistochemistry was used to detect CD3, CD8, Ki-67, TNF-α and IFN-γ in GCA-affected tissues.

RESULTS

GCA patients had decreased numbers of circulating effector memory CD8+ T cells but the percentage of Ki-67-expressing effector memory CD8+ T cells was increased. Circulating CD8+ T cells from GCA patients demonstrated reduced T cell receptor activation thresholds and displayed a gene expression profile that is concurrent with increased proliferation. CD8+ T cells were detected in GCA temporal arteries and aorta. These vascular CD8+ T cells expressed IFN-γ but not Ki-67.

CONCLUSION

In GCA, circulating effector memory CD8+ T cells demonstrate a proliferation-prone phenotype. The presence of CD8+ T cells in inflamed arteries seems to reflect recruitment of circulating cells rather than local expansion. CD8+ T cells in inflamed tissues produce IFN-γ, which is an important mediator of local inflammatory responses in GCA.

Large-Vessel Vasculitis in Ophthalmology: Giant Cell Arteritis and Takayasu Arteritis

ABSTRACT

Giant cell arteritis and Takayasu arteritis are large-vessel vasculitides that share multiple common features but also have significant differences in epidemiology, demographics, clinical presentation, evaluation, and treatment. Giant cell arteritis is more common in elderly patients of Caucasian descent versus Takayasu arteritis, which is more prevalent in younger patients of Asian descent. Although traditionally age has been the main criterion for differentiating the 2 etiologies, modifications in the diagnostic criteria have recognized the overlap between the 2 conditions. In this monograph, we review the diagnostic criteria for both conditions and describe the epidemiology, pathogenesis, histology, evaluation, and management for large-vessel vasculitis in ophthalmology. Additionally, we describe ocular imaging techniques that may be utilized by ophthalmologists to identify manifestations of large-vessel vasculiti- des in patients. Lastly, we compare and contrast the key clinical, laboratory, and pathologic features that might help ophthalmologists to differentiate the 2 entities.

Changes in Colonic Inflammation Related with Takayasu Arteritis during a 10-year Observation Period

Takayasu arteritis (TA) sometimes presents with colitis, which may be diagnosed as inflammatory bowel disease unclassified (IBDU) because of atypical or mixed findings of ulcerative colitis (UC) and Crohn's disease. We herein report an 18-year-old girl presenting with colitis with an occasional high fever eventually diagnosed as TA with IBDU. Colonic inflammation was initially discontinuous and stronger in the proximal colon, atypical of UC. However, over 10-year observation, the distribution of colonic inflammation varied and became UC-like. Variations in TA-related colonic inflammations over time have been unclear. Our long-term observation might help clarify the details of TA-related colonic inflammation.

Large-vessel vasculitis

Large-vessel vasculitis (LVV) manifests as inflammation of the aorta and its major branches and is the most common primary vasculitis in adults. LVV comprises two distinct conditions, giant cell arteritis and Takayasu arteritis, although the phenotypic spectrum of primary LVV is complex. Non-specific symptoms often predominate and so patients with LVV present to a range of health-care providers and settings. Rapid diagnosis, specialist referral and early treatment are key to good patient outcomes. Unfortunately, disease relapse remains common and chronic vascular complications are a source of considerable morbidity. Although accurate monitoring of disease activity is challenging, progress in vascular imaging techniques and the measurement of laboratory biomarkers may facilitate better matching of treatment intensity with disease activity. Further, advances in our understanding of disease pathophysiology have paved the way for novel biologic treatments that target important mediators of disease in both giant cell arteritis and Takayasu arteritis. This work has highlighted the substantial heterogeneity present within LVV and the importance of an individualized therapeutic approach. Future work will focus on understanding the mechanisms of persisting vascular inflammation, which will inform the development of increasingly sophisticated imaging technologies. Together, these will enable better disease prognostication, limit treatment-associated adverse effects, and facilitate targeted development and use of novel therapies.

Age as a risk factor in vasculitis

Two vasculitides, giant cell arteritis (GCA) and Takayasu arteritis (TAK), are recognized as autoimmune and autoinflammatory diseases that manifest exclusively within the aorta and its large branches. In both entities, the age of the affected host is a critical risk factor. TAK manifests during the 2nd-4th decade of life, occurring while the immune system is at its height of performance. GCA is a disease of older individuals, with infrequent cases during the 6th decade and peak incidence during the 8th decade of life. In both vasculitides, macrophages and T cells infiltrate into the adventitia and media of affected vessels, induce granulomatous inflammation, cause vessel wall destruction, and reprogram vascular cells to drive adventitial and neointimal expansion. In GCA, abnormal immunity originates in an aged immune system and evolves within the aged vascular microenvironment. One hallmark of the aging immune system is the preferential loss of CD8⁺ T cell function. Accordingly, in GCA but not in TAK, CD8⁺ effector T cells play a negligible role and anti-inflammatory CD8⁺ T regulatory cells are selectively impaired. Here, we review current evidence of how the process of immunosenescence impacts the risk for GCA and how fundamental differences in the age of the immune system translate into differences in the granulomatous immunopathology of TAK versus GCA.

The Epidemiology and Clinical Manifestations of Takayasu Arteritis: A Descriptive Study of Case Reports

Takayasu's arteritis is a rare form of chronic inflammatory disorder involving large vessels, with an unclear etiology. Common early signs and symptoms are weakness, malaise, and fever. Takayasu's arteritis mainly involves the aorta and its branches as well as the subclavian and carotid arteries. While radiologic methods can identify diseased vessels, they can't tell the difference between active and chronic lesions. This study reviews the characteristics of Takayasu's arteritis to identify any possible changes in the prevalence of symptoms of the disease. We conducted a literature review of case reports on Takayasu arteritis from PubMed and Google Scholar. Variables of interest were age, gender, symptoms, blood pressure (BP) measurement, diminished pulses, and radiological findings. Data were transferred to an Excel spreadsheet (Microsoft Corporation, Redmond, WA), and mean, median, and standard deviation, frequencies, and proportions were calculated using R version 1.1.456 (RStudio: Integrated Development for R. RStudio, PBC, Boston, MA). There were 43 cases, and females accounted for 88.3% of the presentations. The average age was 25 years, SD 12.5 years. Fever was the most frequent symptom (20.93%), followed by chest pain (13.95%), claudication (13.95%), and headache (13.95%). Less frequent complaints included shortness of breath (11.62%), weight loss (9.30%), syncope (6.98%), and night sweats (4.65%). On the right side, the average BP was 142/87 mmHg, and the left-sided finding averaged 115/72 mmHg. Decreased pulses were primarily seen in the radial artery with 15 cases. Radiological findings showed narrowing of the vessels in the following order: aorta (22), carotid (11), renal (10), subclavian (9), celiac (2), mesenteric (2), axillary (2), and tibial (1). The characteristics of Takayasu's arteritis were analyzed in this study. It identified several findings, ranging from fever symptoms to the signs of claudication, as well as the involvement of major vessels, such as the aorta and its branches, and a summary of radiological findings. This depicts the picture of Takayasu's arteritis and what physicians should expect when dealing with the disease.

An update on the pathogenic role of IL-6 in rheumatic diseases

Interleukin (IL)-6 is a pleiotropic cytokine that is involved in the pathogenesis of various rheumatic diseases. Direct inhibition of the IL-6 pathway by an anti-IL-6 receptor or inhibiting the ligand itself has proved to be efficacious in the treatment of these diseases. Juvenile idiopathic arthritis, adult-onset Still's disease, large vessel vasculitis including giant cell arteritis and Takayasu disease, systemic sclerosis, and polymyalgia rheumatica respond well to IL-6 inhibition as expected. However, no clinically meaningful effect has been observed with regard to IL-6 blockade in ankylosing spondylitis, psoriatic arthritis, and systemic lupus erythematosus. This review discusses the current state of IL-6 targeting approaches in various rheumatic diseases other than rheumatoid arthritis.

Coronary Vasculitis

The term coronary “artery vasculitis” is used for a diverse group of diseases with a wide spectrum of manifestations and severity. Clinical manifestations may include pericarditis or myocarditis due to involvement of the coronary microvasculature, stenosis, aneurysm, or spontaneous dissection of large coronaries, or vascular thrombosis. As compared to common atherosclerosis, patients with coronary artery vasculitis are younger and often have a more rapid disease progression. Several clinical entities have been associated with coronary artery vasculitis, including Kawasaki’s disease, Takayasu’s arteritis, polyarteritis nodosa, ANCA-associated vasculitis, giant-cell arteritis, and more recently a Kawasaki-like syndrome associated with SARS-COV-2 infection. This review will provide a short description of these conditions, their diagnosis and therapy for use by the practicing cardiologist.

Poor physical activity levels and cardiorespiratory fitness among patients with childhood-onset takayasu arteritis in remission: a cross-sectional, multicenter study

BACKGROUND

It is currently unknown whether patients with childhood-onset Takayasu disease (c-TA) are prone to physical inactivity and poor aerobic capacity. In this study, we assessed physical activity levels and cardiorespiratory fitness along with health-related quality of life (HRQL) and various traditional and non-traditional risk factors in patients with c-TA vs. healthy controls.

METHODS

c-TA patients with non-active disease (n = 17) and age- and sex-matched healthy controls (n = 17) were enrolled in the study. We assessed physical activity levels, aerobic capacity, body composition, systemic inflammation, cardiometabolic markers, disease-related parameters, and HRQL.

RESULTS

c-TA patients showed greater time spent in sedentary behavior (P = 0.010), and lower moderate-to-vigorous physical activity (P > 0.001) and lower step counts per day (P > 0.001). VO2peak (P < 0.001) and chronotropic response (P = 0.016) were significantly lower in patients with c-TA and they had worse HRQL in physical domain (P < 0.001), lower bone mineral content and density, and higher insulin levels vs. healthy controls (all P ≤ 0.05).

CONCLUSIONS

c-TA patients exhibited reduced physical activity levels and aerobic capacity, worse cardiometabolic risk factors and HRQL parameter compared with healthy peers. Physical inactivity and aerobic deconditioning emerge as potentially novel risk factors for c-TA. The role of physical activity interventions in preventing poor outcomes and improving HRQL in c-TA remains to be explored.

CD8+ T Cells in GCA and GPA: Bystanders or Active Contributors?

Vasculitis refers to inflammation of blood vessels and can cause a variety of serious complications depending on which vessels are affected. Two different forms of vasculitis are Giant Cell Arteritis (GCA) and Granulomatosis with Polyangiitis (GPA). GCA is the most common form of vasculitis in adults affecting the large arteries and can lead to visual impairment and development of aneurysms. GPA affects small- and medium-sized blood vessels predominantly in the lungs and kidneys resulting in organ failure. Both diseases can potentially be fatal. Although the pathogenesis of GCA and GPA are incompletely understood, a prominent role for CD4+ T cells has been implicated in both diseases. More recently, the role of CD8+ T cells has gained renewed interest. CD8+ T cells are important players in the adaptive immune response against intracellular microorganisms. After a general introduction on the different forms of vasculitis and their association with infections and CD8+ T cells, we review the current knowledge on CD8+ T-cell involvement in the immunopathogenesis of GCA and GPA focusing on phenotypic and functional features of circulating and lesional CD8+ T cells. Furthermore, we discuss to which extent aging is associated with CD8+ T-cell phenotype and function in GCA and GPA.

The Immunopathology of Giant Cell Arteritis Across Disease Spectra

Giant cell arteritis (GCA) is a granulomatous systemic vasculitis of large- and medium-sized arteries that affects the elderly. In recent years, advances in diagnostic imaging have revealed a greater degree of large vessel involvement than previously recognized, distinguishing classical cranial- from large vessel (LV)- GCA. GCA often co-occurs with the poorly understood inflammatory arthritis/bursitis condition polymyalgia rheumatica (PMR) and has overlapping features with other non-infectious granulomatous vasculitides that affect the aorta, namely Takayasu Arteritis (TAK) and the more recently described clinically isolated aortitis (CIA). Here, we review the literature focused on the immunopathology of GCA on the background of the three settings in which comparisons are informative: LV and cranial variants of GCA; PMR and GCA; the three granulomatous vasculitides (GCA, TAK, and CIA). We discuss overlapping and unique features between these conditions across clinical presentation, epidemiology, imaging, and conventional histology. We propose a model of GCA where abnormally activated circulating cells, especially monocytes and CD4+ T cells, enter arteries after an unknown stimulus and cooperate to destroy it and review the evidence for how this mechanistically occurs in active disease and improves with treatment.

Cellular Signaling Pathways in Medium and Large Vessel Vasculitis

Autoimmune and autoinflammatory diseases of the medium and large arteries, including the aorta, cause life-threatening complications due to vessel wall destruction but also by wall remodeling, such as the formation of wall-penetrating microvessels and lumen-stenosing neointima. The two most frequent large vessel vasculitides, giant cell arteritis (GCA) and Takayasu arteritis (TAK), are HLA-associated diseases, strongly suggestive for a critical role of T cells and antigen recognition in disease pathogenesis. Recent studies have revealed a growing spectrum of effector functions through which T cells participate in the immunopathology of GCA and TAK; causing the disease-specific patterning of pathology and clinical outcome. Core pathogenic features of disease-relevant T cells rely on the interaction with endothelial cells, dendritic cells and macrophages and lead to vessel wall invasion, formation of tissue-damaging granulomatous infiltrates and induction of the name-giving multinucleated giant cells. Besides antigen, pathogenic T cells encounter danger signals in their immediate microenvironment that they translate into disease-relevant effector functions. Decisive signaling pathways, such as the AKT pathway, the NOTCH pathway, and the JAK/STAT pathway modify antigen-induced T cell activation and emerge as promising therapeutic targets to halt disease progression and, eventually, reset the immune system to reestablish the immune privilege of the arterial wall.

Pathogenesis of Giant Cell Arteritis and Takayasu Arteritis-Similarities and Differences

PURPOSE OF REVIEW

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are auto-inflammatory and autoimmune diseases with a highly selective tissue tropism for medium and large arteries. In both diseases, CD4⁺ T cells and macrophages form granulomatous lesions within the arterial wall, a tissue site normally protected by immune privilege. Vascular lesions can be accompanied by an extravascular component, typically an intense hepatic acute phase response that produces well-known laboratory abnormalities, e.g., elevated ESR and CRP. It is unclear whether GCA and TAK lie on a spectrum of disease or whether they represent fundamentally different disease processes.

RECENT FINDINGS

GCA and TAK share many clinical features, but there are substantial differences in genetics, epidemiology, disease mechanisms, response to treatment, and treatment complications that give rise to different disease trajectories. A significant difference lies in the composition of the wall-infiltrating immune cell compartment, which in TAK includes a significant population of CD8⁺ T cells as well as natural killer cells, specifying disparate disease effector pathways mediating tissue damage and vessel wall remodeling. Despite the similarities in tissue tropism and histomorphology, GCA and TAK are two distinct vasculitides that rely on separate disease mechanisms and require disease-specific approaches in diagnosis and management.

Associations between clinical features and therapy with macrophage subpopulations and T cells in inflammatory lesions in the aorta from patients with Takayasu arteritis

Takayasu arteritis (TAK) is a large-vessel granulomatous vasculitis; the inflammatory infiltration in arteries comprises macrophages, multi-nucleated giant cells, CD4⁺ and CD8⁺ T cells, γδ T cells, natural killer (NK) cells and neutrophils. However, it is unknown which subtype of macrophages predominates. This study aims to evaluate macrophages subpopulations in the aorta in TAK. Immunohistochemistry was performed in the aorta from TAK patients (n = 22), patients with atherosclerotic disease (n = 9) and heart transplant donors (n = 8) using the markers CD68, CD86, CD206, CD3, CD20 and CD56. Active disease was observed in 54·5% of patients and active histological lesions were found in 40·9%. TAK patients presented atherosclerotic lesions in 27·3% of cases. The frequency of macrophages, M1 macrophages, T, B and NK cells was higher in the aorta from TAK and atherosclerotic patients compared to heart transplant donors. In TAK, macrophages and T cells were the most abundant cells in the aorta, and the expression of CD206 was higher than CD86 (P = 0·0007). No associations were found between the expression of cell markers and active disease or with atherosclerotic lesions. In TAK patients, histological disease activity led to higher T cell counts than chronic fibrotic lesions (P = 0.030), whereas prednisone use was associated with lower T cell counts (P = 0·035). In conclusion, M1 macrophages were more frequent in TAK and atherosclerotic patients compared to heart transplant donors, while M2 macrophages dominated M1 macrophages in TAK. T cells were associated with histological disease activity and with prednisone use in TAK.

Roles of cytotoxic lymphocytes and MIC/LILR families in pathophysiology of Takayasu arteritis

Takayasu arteritis (TAK) affects the aorta and its primary branches, mainly in young women. In its advanced stages, it can cause severe complications, such as cerebral infarction, impaired vision, and valvular heart diseases. In the aortic tissue of TAK, there is increased infiltration of cytotoxic lymphocytes, such as natural killer (NK) cells and CD8⁺T cells, and enhanced expression of accessory molecules, such as major histocompatibility complex (MHC) and MHC class I chain-related gene (MIC) family. Genome-wide association studies on TAK have identified susceptibility genes, such as IL-12p40, MICA, MICB, leukocyte immunoglobulin-like receptor A3 (LILRA3), and LILRB3. Other studies have also shown their involvement in the pathophysiology of TAK. In addition, we reported the importance of NK cells by enhancer enrichment analysis. These results suggest that the gene polymorphisms that potentially upregulate the expression of cytokines and accessory molecules, which contribute to the activation of cytotoxic lymphocytes, are associated with the development of TAK. Based on these results, new molecular targeted therapies look promising.

Axillobifemoral bypass for total abdominal occlusion secondary to Takayasu's arteritis: A case report

INTRODUCTION

Takayasu's arteritis (TA) is a rare disease that mainly affects large arteries. Approximately 20% of TA patients will require surgical intervention secondary to arterial complications such as intermittent claudication, persistent hypertension refractory to treatment, and heart failure.

PRESENTATION OF CASE

The case of a 22-year-old female with TA of five years of evolution is presented. The patient deteriorated clinically after five years of corticosteroid and immunosuppressant management requiring surgical intervention with an axillobifemoral bypass for a total abdominal occlusion. Onset, pre-surgical and post-surgical Doppler ultrasonography as well as abdominal angiotomographies document and corroborate the patient's clinical and hemodynamic improvement.

DISCUSSION

Very limited literature exists regarding surgical interventions for TA patients. While most reported cases present an endovascular surgical management. Open surgical procedures have lower rates of restenosis than endovascular management. Although endovascular management is less invasive than extra-anatomical axillobifemoral bypass, the patient was not a candidate for endovascular stent graft placement due to the increased risk for vascular injury and subsequent perforation. Approximately a fifth of TA patients are candidates for surgical intervention over time.

CONCLUSION

Vascular surgery in TA cases becomes an option when the patient does not improve clinically after administration of medical treatment. Although endovascular management has fewer complications, the rate of restenosis is higher. Patients at risk of restenosis and who have increased perioperative vascular risk can benefit from open surgical procedures. Surgical management should be tailored to the patient's needs.

Statins reduce relapse rate in Takayasu arteritis

BACKGROUND

To investigate the effect of statins on relapse of Takayasu arteritis (TAK), which frequently occurs after achievement of remission.

METHODS

We conducted a retrospective study on TAK patients with active disease, diagnosed between 2012 and 2017. Relapse was defined as recurrence of active disease after achieving remission. Demographic and clinical parameters of patients who experienced relapse were compared to those who did not. To identify factors associated with relapse, significant factors identified in this comparison were included in a multivariate Cox regression analysis. Inverse probability of treatment weighting (IPTW)-adjusted analysis was used to evaluate the influence of statins on relapse.

RESULTS

Of the total 74 TAK patients, 40 (54.1%) patients received statins, whereas 34 (45.9%) patients did not. Relapse was observed in 36 (48.6%) patients of the total 74 TAK patients. Compared with patients who did not experience relapse, patients who experienced relapse were younger (44.5 ± 13.5 years vs 34.1 ± 12.6 years, p = 0.001), had lower prevalence of hypertension (63.2% vs 38.9%, p = 0.037), more commonly had carotidynia (7.9% vs 27.8%, p = 0.025), had higher LDL-cholesterol (84.8 ± 18.8 mg/dl vs 100.5 ± 26.1 mg/dl, p = 0.010), and were less commonly taking statins (71.1% vs 36.1%, p = 0.003). The use of statins was significant in multivariate Cox regression analysis (adjusted hazard ratio 0.260, 95% confidence interval 0.120-0.563, p = 0.001). Furthermore, IPTW-adjusted analysis confirmed that statin use was associated with a lower risk of relapse (IPTW-adjusted hazard ratio 0.153, 95% confidence interval 0.038-0.616, p = 0.008).

CONCLUSION

In TAK, statins can be beneficial in reducing relapse rate after achieving remission.

Pathophysiology of large vessel vasculitis and utility of interleukin-6 inhibition therapy

Takayasu arteritis (TAK) and giant cell arteritis (GCA) affect mainly large- and medium-sized arteries. In refractory cases, vascular remodeling progresses and leads to serious outcomes. Studies have demonstrated that cytokines such as interleukin (IL)-6 play crucial roles in the pathophysiology of TAK and GCA. Recently, randomized controlled trials on IL-6 inhibition therapy using tocilizumab (TCZ) were performed, and significant effects were exhibited. The purposes of conventional treatments have been to improve symptoms and decrease the levels of inflammatory markers. Arterial changes have been considered as damages. However, after TCZ came into practical use, establishment of treat to target is desired to prevent vascular remodeling. In contrast, a combination therapy of glucocorticoids (GCs) and TCZ notably increases the risk of infections. When TCZ is used, careful attention must be paid to possible infections, and dose of GC should be tapered as much as possible. Future tasks are to establish indication and dosage of TCZ, indication for discontinuation of TCZ due to remission, efficacy of TCZ monotherapy, and protocols of TCZ for pediatric cases.

Microparticles from Endothelial Cells and Immune Cells in Patients with Takayasu Arteritis

AIM

This study was designed to analyze microparticles (MPs) from endothelial cells (EMPs) and immune cells from healthy individuals and paitents with Takayasu arteritis (TA), and any possible relationships between MPs and TA acitivity.

METHODS

MPs derived from the plasma of 51 subjects were analyzed, including 32 patients with TA and 19 healthy individuals. Flow cytometry was performed with Annexin (Anx)-V and antibodies against surface markers of endothelial cells (CD144), T cells (CD3), B cells (CD19), and monocytes (CD14).

RESULTS

The concentrations of total EMPs, AnxV＋ EMPs and AnxV- EMPs were significantly increased when comparing patients with TA and healthy controls (54×10³ vs. 32×10³ MPs /ml, P=0.0004; 22×10³ vs. 12×10³ MPs /ml, P=0.0006; and 31×10³ vs. 19×10³ MPs /ml, P=0.0005), and comparing active TA patients with remission ones (85×10³ vs. 45×10³ MPs /ml, P=0.016; 39×10³ vs. 14×10³ MPs /ml, P=0.0092; and 47×10³ vs.29×10³ MPs /ml, P=0.0371). In addition, the concentrations of total EMPs (odds ratio [OR]=1.024, 95% confidence interval [CI]: 1.001 to 1.048, P=0.037), AnxV＋(OR=1.089, 95%CI: 1.011 to 1.172, P=0.024), and AnxV- EMPs (OR=1.029, 95% CI: 1.002 to 1.056, P=0.034) were positively related to TA activity. With multiple linear regression analysis, platelet was associated with both total and AnxV- EMP concentrations independently, while erythrocyte sedimentation rate was independently correlated with AnxV＋EMPs.

CONCLUSION

Concentrations of endothelial microparticles are correlated with inflammation in Takayasu arteritis and may be useful markers to assess disease activity.

Genetic determinants and an epistasis of LILRA3 and HLA-B*52 in Takayasu arteritis

Takayasu arteritis (TAK) is a systemic vasculitis with severe complications that affects the aorta and its large branches. HLA-B*52 is an established susceptibility locus to TAK. To date, there are still only a limited number of reports concerning non-HLA susceptibility loci to TAK. We conducted a genome-wide association study (GWAS) and a follow-up study in a total of 633 TAK cases and 5,928 controls. A total of 510,879 SNPs were genotyped, and 5,875,450 SNPs were imputed together with HLA-B*52. Functional annotation of significant loci, enhancer enrichment, and pathway analyses were conducted. We identified four unreported significant loci, namely rs2322599, rs103294, rs17133698, and rs1713450, in PTK2B, LILRA3/LILRB2, DUSP22, and KLHL33, respectively. Two additional significant loci unreported in non-European GWAS were identified, namely HSPA6/FCGR3A and chr21q.22. We found that a single variant associated with the expression of MICB, a ligand for natural killer (NK) cell receptor, could explain the entire association with the HLA-B region. Rs2322599 is strongly associated with the expression of PTK2B Rs103294 risk allele in LILRA3/LILRB2 is known to be a tagging SNP for the deletion of LILRA3, a soluble receptor of HLA class I molecules. We found a significant epistasis effect between HLA-B*52 and rs103294 (P = 1.2 × 10^-3). Enhancer enrichment analysis and pathway analysis suggested the involvement of NK cells (P = 8.8 × 10^-5, enhancer enrichment). In conclusion, four unreported TAK susceptibility loci and an epistasis effect between LILRA3 and HLA-B*52 were identified. HLA and non-HLA regions suggested a critical role for NK cells in TAK.

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.

New Insights on the Pathogenesis of Takayasu Arteritis: Revisiting the Microbial Theory

Takayasu arteritis (TAK) is a chronic vasculitis that mainly affects the aorta, its major branches, and the pulmonary arteries. Since the description of the first case by Mikito Takayasu in 1908, several aspects of this rare disease, including the epidemiology, diagnosis, and the appropriate clinical assessment, have been substantially defined. Nevertheless, while it is well-known that TAK is associated with a profound inflammatory process, possibly rooted to an autoimmune disorder, its precise etiology has remained largely unknown. Efforts to identify the antigen(s) that trigger autoimmunity in this disease have been unsuccessful, however, it is likely that viruses or bacteria, by a molecular mimicry mechanism, initiate or propagate the auto-immune process in this disease. In this article, we summarize recent advances in the understanding of TAK, with emphasis on new insights related to the pathogenesis of this entity that may contribute to the design of novel therapeutic approaches.