# The Role of C/EBP‐Homologous Protein in Idiopathic Inflammatory Myopathies

## TL;DR

This study explores the role of CHOP in idiopathic inflammatory myopathies, linking it to muscle damage and fibrosis, and suggests it as a potential therapeutic target.

## Contribution

The study identifies CHOP and CD206 positive cells as key players in the progression of idiopathic inflammatory myopathies.

## Key findings

- Higher necrotic fibres correlate with increased CD206 positive cells and ER stress.
- CHOP contributes to fibrosis and inflammatory processes in IIM patients.
- Altered capillary networks and connective tissue deposition were observed in patients with more necrotic fibres.

## Abstract

The Idiopathic Inflammatory Myopathies (IIMs) are a group of autoimmune disorders characterised by persistent muscle inflammation and diverse clinical manifestations. Common symptoms include muscle weakness, myalgia, and elevated serum creatine kinase levels. Recent findings highlight the relevance of muscle fibre necrosis in IIMs. We therefore grouped our IIM patients according to the percentage of necrotic fibres in muscle biopsy. Our clustered patients were analysed for the inflammatory milieu, the capillary network, and the endoplasmic reticulum stress. In patients with a higher percentage of necrotic fibres we detected a more marked presence of CD206 positive cells, an activation of the endothelial–mesenchymal transition process, an altered capillary network, more marked ER stress and connective tissue deposition. Furthermore, our study revealed a key role of C/EBP‐homologous protein (CHOP), a multifunctional transcription factor that contributes to cellular functions including apoptosis, autophagy, inflammation, mediation of ER stress and induction of fibrosis. Our study suggests that CD206 positive cells and CHOP have an important role in pathogenetic mechanisms and could therefore be considered possible therapeutic targets to modulate the inflammatory response of these patients, namely to contain or slow down the progression of fibrosis.