# Immune-Mediated Necrotizing Myopathy (IMNM): A Story of Antibodies

## TL;DR

This paper reviews the role of specific antibodies in causing and diagnosing immune-mediated necrotizing myopathy, a rare muscle disease.

## Contribution

The paper provides a comprehensive overview of anti-SRP and anti-HMGCR antibodies in IMNM, their detection methods, and their role in disease mechanisms.

## Key findings

- Anti-SRP and anti-HMGCR antibodies are present in two-thirds of IMNM patients and are key diagnostic markers.
- In vitro and mouse studies suggest these autoantibodies contribute to muscle damage in IMNM.
- Recent therapeutic strategies for IMNM are reviewed based on current understanding of antibody-mediated pathogenesis.

## Abstract

Immune-mediated necrotizing myopathy (IMNM) is a rare and severe disease that corresponds to a specific entity of idiopathic inflammatory myopathy. Patients with IMNM suffer from proximal muscle weakness, and present high levels of creatine kinase and necrotic myofibers. Anti-Signal Recognition Particle (SRP) and anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase autoantibodies (HMGCR) have recently been identified in two thirds of patients with IMNM and are used as a hallmark of the disease. In this review, we provide a detailed description of these antibodies and the tests used to detect them in the serum of patients. Based on in vitro studies and mouse models of IMNM, we discuss the role of autoantibodies in the pathogenesis of the disease. Finally, in the light of the latest knowledge, we conclude with a review of recent therapeutic approaches in IMNM.