Anti-SRP immune-mediated necrotizing myopathy: A critical review of current concepts

• Published in: Frontiers in immunology Vol. 13; p. 1019972
• Main Authors: Ma, Xue, Bu, Bi-Tao
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 13-10-2022
• Subjects: anti-SRP autoantibodies; cardiac involvement; ER stress; immune-mediated necrotizing myopathy; Immunology; refractory
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2022.1019972

Purpose of review This review aims to describe clinical and histological features, treatment, and prognosis in patients with anti-signal recognition particle (SRP) autoantibodies positive immune-mediated necrotizing myopathy (SRP-IMNM) based on previous findings. Previous findings Anti-SRP autoantibodies are specific in IMNM. Humoral autoimmune and inflammatory responses are the main autoimmune characteristics of SRP-IMNM. SRP-IMNM is clinically characterized by acute or subacute, moderately severe, symmetrical proximal weakness. Younger patients with SRP-IMNM tend to have more severe clinical symptoms. Patients with SRP-IMNM may be vulnerable to cardiac involvement, which ought to be regularly monitored and cardiac magnetic resonance imaging is the recommended detection method. The pathological features of SRP-IMNM are patchy or diffuse myonecrosis and myoregeneration accompanied by a paucity of inflammatory infiltrates. Endoplasmic reticulum stress-induced autophagy pathway and necroptosis are activated in skeletal muscle of SRP-IMNM. Treatment of refractory SRP-IMNM encounters resistance and warrants further investigation. Summary Anti-SRP autoantibodies define a unique population of IMNM patients. The immune and non-immune pathophysiological mechanisms are involved in SRP-IMNM.