My Treatment Approach to Giant Cell Arteritis

Plasma proteome profiling in giant cell arteritis

OBJECTIVES

This study aimed to identify plasma proteomic signatures that differentiate active and inactive giant cell arteritis (GCA) from non-disease controls. By comprehensively profiling the plasma proteome of both patients with GCA and controls, we aimed to identify plasma proteins that (1) distinguish patients from controls and (2) associate with disease activity in GCA.

METHODS

Plasma samples were obtained from 30 patients with GCA in a multi-institutional, prospective longitudinal study: one captured during active disease and another while in clinical remission. Samples from 30 age-matched/sex-matched/race-matched non-disease controls were also collected. A high-throughput, aptamer-based proteomics assay, which examines over 7000 protein features, was used to generate plasma proteome profiles from study participants.

RESULTS

After adjusting for potential confounders, we identified 537 proteins differentially abundant between active GCA and controls, and 781 between inactive GCA and controls. These proteins suggest distinct immune responses, metabolic pathways and potentially novel physiological processes involved in each disease state. Additionally, we found 16 proteins associated with disease activity in patients with active GCA. Random forest models trained on the plasma proteome profiles accurately differentiated active and inactive GCA groups from controls (95.0% and 98.3% in 10-fold cross-validation, respectively). However, plasma proteins alone provided limited ability to distinguish between active and inactive disease states within the same patients.

CONCLUSIONS

This comprehensive analysis of the plasma proteome in GCA suggests that blood protein signatures integrated with machine learning hold promise for discovering multiplex biomarkers for GCA.

Estimating overdiagnosis in giant cell arteritis diagnostic pathways using genetic data: genetic association study

OBJECTIVES

GCA can be confirmed by temporal artery biopsy (TAB) but false negatives can occur. GCA may be overdiagnosed in TAB-negative cases, or if neither TAB nor imaging is done. We used HLA genetic association of TAB-positive GCA as an 'unbiased umpire' test to estimate historic overdiagnosis of GCA.

METHODS

Patients diagnosed with GCA between 1990 and 2014 were genotyped. During this era, vascular imaging alone was rarely used to diagnose GCA. HLA region variants were jointly imputed from genome-wide genotypic data of cases and controls. Per-allele frequencies across all HLA variants with P < 1.0 × 10-5 were compared with population control data to estimate overdiagnosis rates in cases without a positive TAB.

RESULTS

Genetic data from 663 GCA patients were compared with data from 2619 population controls. TAB-negative GCA (n = 147) and GCA without TAB result (n = 160) had variant frequencies intermediate between TAB-positive GCA (n = 356) and population controls. For example, the allele frequency of HLA-DRB1*04 was 32% for TAB-positive GCA, 29% for GCA without TAB result, 27% for TAB-negative GCA and 20% in population controls. Making several strong assumptions, we estimated that around two-thirds of TAB-negative cases and one-third of cases without TAB result may have been overdiagnosed. From these data, TAB sensitivity is estimated as 88%.

CONCLUSIONS

Conservatively assuming 95% specificity, TAB has a negative likelihood ratio of around 0.12. Our method for utilizing standard genotyping data as an 'unbiased umpire' might be used as a way of comparing the accuracy of different diagnostic pathways.

Thoracic Aortic Aneurysmal Disease: Comprehensive Recommendations for the Primary Care Physician

Thoracic aortic aneurysm (TAA) is a commonly encountered disease that is defined as aortic dilation with an increase in diameter of at least 50% greater than the expected age- and sex-adjusted size. Thoracic aortic aneurysms are described by their size, location, morphology, and cause. Primary care clinicians and other noncardiologists are often the first point of contact for patients with TAA. This review is intended to provide them with basic information on the differential diagnosis, diagnostic evaluation, and medical and surgical management of TAAs. Management decisions depend on having as precise a diagnosis as possible. Fortunately, this can often be achieved with a stepwise diagnostic approach that incorporates imaging and targeted genetic testing. Our review includes recommendations. In this review, we discuss these issues at a basic level and include recommendations for patients considering pregnancy.

Positron Emission Tomography (PET) Scan as a Diagnostic Tool for Giant Cell Arteritis

Giant cell arteritis (GCA) is an inflammatory vasculitis that typically affects the elderly, preferentially involving large and medium-sized arteries and can potentially cause irreversible loss of vision. Early diagnosis and treatment are necessary to prevent this dreaded complication. Temporal artery biopsy has been the gold standard test in diagnosing GCA, however, false negative results due to presence of skip lesions, restricted inflammation, and early initiation of steroids have limited its diagnostic significance. We report a case of a 67-year-old female with headache, blurry vision, posterior scalp tenderness, feeble left temporal artery pulse on a physical exam with normal inflammatory markers. Temporal artery biopsy showed disruption and reduplication of internal elastic lamina without any evidence of giant cells or inflammatory cells. Owing to high clinical suspicion, fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) was further done which revealed mildly increased uptake in the thoracic aorta, consistent with a diagnosis of large vessel vasculitis.

Temporal artery biopsy

Giant cell arteritis is a common vasculitis in patients over the age of 50 years old. If not promptly recognized and aggressively treated with high-dose glucocorticoids, ischemia resulting in permanent vision loss or stroke can occur. Yet, the treatment with high-dose glucocorticoids over a long period of time can be problematic in this particular patient population given their age and associated comorbidities. Temporal artery biopsies (TAB) are an important diagnostic tool to evaluate patients with suspected giant cell arteritis. Herein, we explore indications for TAB and practical points in obtaining a TAB based on available evidence. We review the surgical procedure itself and associated complications. Lastly, we examine common pathological findings and considerations of alternative diagnoses.

Giant Cell Arteritis Mimicking Polymyalgia Rheumatica: A Challenging Diagnosis

Giant cell arteritis (GCA) is an autoimmune disease that causes inflammation of the middle and large arteries. Rural areas have many older patients with various symptoms, so large-vessel-type GCA should be managed effectively. Older patients tend to show vague symptoms that cannot be adequately diagnosed and observed. Here, we have encountered a case of a 91-year-old woman with a chief complaint of fatigue diagnosed with large-vessel type GCA in collaboration with a rural clinic. Effective collaboration between physicians in rural hospitals and clinics is necessary for diagnosing and treating large-vessel GCA. In rural areas, without adequate healthcare professionals, physicians should share their abilities and collaborate smoothly to mitigate delays in consultation and treatment. To effectively treat large vessel-type GCA, rural general physicians should be familiar with the clinical course of the disease and treatment for rural comprehensive care.

Advances in the Treatment of Giant Cell Arteritis

Giant cell arteritis (GCA) is the most common vasculitis among elderly people. The clinical spectrum of the disease is heterogeneous, with a classic/cranial phenotype, and another extracranial or large vessel phenotype as the two more characteristic patterns. Permanent visual loss is the main short-term complication. Glucocorticoids (GC) remain the cornerstone of treatment. However, the percentage of relapses with GC alone is high, and the rate of adverse events affects more than 80% of patients, so it is necessary to have alternative therapeutic options, especially in patients with worse prognostic factors or high comorbidity. MTX is the only DMARD that has shown to reduce the cumulative dose of GC, while tocilizumab is the first biologic agent approved due to its ability to decrease the relapse rate and lower the cumulative GC doses. However, apart from the IL-6 pathway, there are other pro-inflammatory cytokines and growth factors involved in the typical intima hyperplasia and vascular remodeling of GCA. Among them, the more promising targets in GCA treatment are the IL12/IL23 axis antagonists, IL17 inhibitors, modulators of T lymphocytes, and inhibitors of either the JAK/STAT pathway, the granulocyte-macrophage colony-stimulating factor, or the endothelin, all of which are updated in this review.