Abatacept in early polymyalgia rheumatica (ALORS): a proof-of-concept, randomised, placebo-controlled, parallel-group trial

Immune checkpoints in autoimmune vasculitis

Giant cell arteritis (GCA) is a prototypic autoimmune disease with a highly selective tissue tropism for medium and large arteries. Extravascular GCA manifests with intense systemic inflammation and polymyalgia rheumatica; vascular GCA results in vessel wall damage and stenosis, causing tissue ischemia. Typical granulomatous infiltrates in affected arteries are composed of CD4+ T cells and hyperactivated macrophages, signifying the involvement of the innate and adaptive immune system. Lesional CD4+ T cells undergo antigen-dependent clonal expansion, but antigen-nonspecific pathways ultimately control the intensity and duration of pathogenic immunity. Patient-derived CD4+ T cells receive strong co-stimulatory signals through the NOTCH1 receptor and the CD28/CD80-CD86 pathway. In parallel, co-inhibitory signals, designed to dampen overshooting T cell immunity, are defective, leaving CD4+ T cells unopposed and capable of supporting long-lasting and inappropriate immune responses. Based on recent data, two inhibitory checkpoints are defective in GCA: the Programmed death-1 (PD-1)/Programmed cell death ligand 1 (PD-L1) checkpoint and the CD96/CD155 checkpoint, giving rise to the "lost inhibition concept". Subcellular and molecular analysis has demonstrated trapping of the checkpoint ligands in the endoplasmic reticulum, creating PD-L1low CD155low antigen-presenting cells. Uninhibited CD4+ T cells expand, release copious amounts of the cytokine Interleukin (IL)-9, and differentiate into long-lived effector memory cells. These data place GCA and cancer on opposite ends of the co-inhibition spectrum, with cancer patients developing immune paralysis due to excessive inhibitory checkpoints and GCA patients developing autoimmunity due to nonfunctional inhibitory checkpoints.

Recommendations of the French Society of Rheumatology for the management in current practice of patients with polymyalgia rheumatica

OBJECTIVE

To develop recommendations for the routine management of patients with polymyalgia rheumatica (PMR).

METHODS

Following standard procedures, a systematic review of the literature by five supervised junior rheumatologists, based on the questions selected by the steering committee (5 senior rheumatologists), was used as the basis for working meetings, followed by a one-day plenary meeting with the working group (15 members), leading to the development of the wording and determination of the strength of the recommendations and the level of agreement of the experts.

RESULTS

Five general principles and 19 recommendations were drawn up. Three recommendations relate to diagnosis and the use of imaging, and five to the assessment of the disease, its activity and comorbidities. Non-pharmacological therapies are the subject of one recommendation. Three recommendations concern initial treatment based on general corticosteroid therapy, five concern the reduction of corticosteroid therapy and follow-up, and two concern corticosteroid dependence and steroid-sparing treatments (anti-IL-6).

CONCLUSION

These recommendations take account of current data on PMR, with the aim of reducing exposure to corticosteroid therapy and its side effects in a fragile population. They are intended to be practical, to help practitioners in the day-to-day management of patients with PMR.