Interleukin-6: a promising target for the treatment of polymyalgia rheumatica or giant cell arteritis?

Abstract

Polymyalgia rheumatica (PMR) is a chronic inflammatory disease of unknown aetiology affecting people aged over 50. The hallmark manifestations of PMR are pain and stiffness affecting the neck and shoulder and pelvic girdles. There is no specific laboratory test for the disease, and thus the diagnosis of PMR depends on a combination of clinical symptoms, raised acute phase reactants, the exclusion of other diagnoses and response to glucocorticoids (GCs).1 For classification purposes, a number of criteria have been proposed and the most recent were collectively drawn up by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR).2 Giant cell arteritis (GCA) is a type of vasculitis of large-sized and medium-sized arteries affecting people aged over 50. The disease usually involves aorta, supra-aortic branches and the extracranial branches of the carotid artery. The clinical manifestations include headaches, temporal artery or scalp tenderness, jaw claudication, visual symptoms, constitutional symptoms and PMR manifestations.3 At the time of diagnosis, the most serious consequence of GCA is the occurrence of visual loss in 12–14% of patients.4 Aortic aneurysm or dissection may develop during follow-up and can be potentially life-threatening. The gold standard for the diagnosis of GCA remains temporal artery biopsy (TAB). Approximately 60–80% of TABs show evidence of vasculitis with a mononuclear cell infiltrate, disruption of the internal elastic lamina and multinucleated giant cells, the hallmark of the disease, in ∼50% of patients.5 However, ACR classification criteria were developed in patients who already have evidence of vasculitis and do not take into account the additional value of imaging techniques.6 Indeed, ultrasonography of TAB may reveal a hypoechoic halo sign and is considered to be highly specific for GCA diagnosis despite interobserver and interstudy discrepancies.7 In addition, positron emission tomography (PET) is a valuable …