Drug therapies for polymyalgia rheumatica: a pharmacotherapeutic update

Introduction: Polymyalgia rheumatica (PMR), a common disease in individuals older than 50 in the western world, is characterized by bilateral inflammatory pain involving the shoulder girdle and less commonly the neck and pelvic girdle. The main goals of the currently available treatment are to induce remission and prevent relapse.

Areas covered: This review briefly presents the main epidemiological and clinical features of PMR and discusses in depth both its classical management as well as new therapies used in PMR.

Expert opinion: In general, patients with isolated PMR experience a rapid response (in less than seven days) to 12.5–25 mg/prednisone/day. Methotrexate is the conventional disease-modifying antirheumatic drug most commonly used for disease management, especially for relapses of the disease. However, this agent often yields a modest effect. Randomized controlled trials do not support the use of antitumor necrosis factor agents in PMR. Several case series and retrospective studies have highlighted the efficacy of the anti-interleukin-6 receptor antibody tocilizumab in PMR. However, controlled trials are needed to fully establish the efficacy of this biologic agent in PMR. The potential beneficial effect of the Janus-kinase inhibitors remains to be determined.     

Switching cell penetrating and CXCR4-binding activities of nanoscale-organized arginine-rich peptides

Arginine-rich protein motifs have been described as potent cell-penetrating peptides (CPPs) but also as rather specific ligands of the cell surface chemokine receptor CXCR4, involved in the infection by the human immunodeficiency virus (HIV). Polyarginines are commonly used to functionalize nanoscale vehicles for gene therapy and drug delivery, aimed to enhance cell penetrability of the therapeutic cargo. However, under which conditions these peptides do act as either unspecific or specific ligands is unknown. We have here explored the cell penetrability of differently charged polyarginines in two alternative presentations, namely as unassembled fusion proteins or assembled in multimeric protein nanoparticles. By this, we have observed that arginine-rich peptides switch between receptor-mediated and receptor-independent mechanisms of cell penetration. The relative weight of these activities is determined by the electrostatic charge of the construct and the oligomerization status of the nanoscale material, both regulatable by conventional protein engineering approaches.