Cytotoxic T-Lymphocyte-Associated Protein 4 Fused to a Modified Fragment of IgG1 Reduces Muscle Fiber Damage in a Model of Duchenne Muscular Dystrophy by Attenuating Proinflammatory Gene Expression in Myeloid Lineage Cells

Michelle Wehling-Henricks; Su-Yin Kok; Haley Gamboa; Pranav Kannan; Connor Thomas; Ivan Flores; Steven S Welc; James G Tidball

doi:10.1016/j.ajpath.2024.12.012

Cytotoxic T-Lymphocyte-Associated Protein 4 Fused to a Modified Fragment of IgG1 Reduces Muscle Fiber Damage in a Model of Duchenne Muscular Dystrophy by Attenuating Proinflammatory Gene Expression in Myeloid Lineage Cells

Am J Pathol. 2025 Jan 13:S0002-9440(25)00003-3. doi: 10.1016/j.ajpath.2024.12.012. Online ahead of print.

Authors

Michelle Wehling-Henricks¹, Su-Yin Kok¹, Haley Gamboa¹, Pranav Kannan², Connor Thomas¹, Ivan Flores³, Steven S Welc⁴, James G Tidball⁵

Affiliations

¹ Department of Integrative Biology and Physiology, University of California, Los Angeles, California.
² Department of Integrative Biology and Physiology, University of California, Los Angeles, California; Molecular, Cellular and Integrative Physiology Program, University of California, Los Angeles, California.
³ Molecular, Cellular and Integrative Physiology Program, University of California, Los Angeles, California.
⁴ Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana; Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana.
⁵ Department of Integrative Biology and Physiology, University of California, Los Angeles, California; Molecular, Cellular and Integrative Physiology Program, University of California, Los Angeles, California; Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, University of California, Los Angeles, California. Electronic address: jtidball@physci.ucla.edu.

PMID: 39814100
DOI: 10.1016/j.ajpath.2024.12.012

Abstract

Duchenne muscular dystrophy (DMD) is a lethal, muscle-wasting, genetic disease that is greatly amplified by an immune response to the diseased muscles. The mdx mouse model of DMD was used to test whether the pathology can be reduced by treatments with a cytotoxic T-lymphocyte-associated protein 4 fused to a modified fragment of IgG1 (CTLA4-Ig) fusion protein that blocks costimulatory signals required for activation of T cells. CTLA4-Ig treatments reduced mdx sarcolemma lesions and reduced the numbers of activated T cells, macrophages, and antigen-presenting cells in mdx muscle and reduced macrophage invasion into muscle fibers. In vitro data showed that CTLA4-Ig acts directly on bone marrow cells and macrophages to modify their function and gene expression. CTLA4-Ig treatments of mdx bone marrow cells diminished their mobility and chemotactic response to chemokine ligand-2. Treating mdx macrophages with CTLA4-Ig reduced their cytolysis of muscle cells in vitro. RNA-sequencing analysis of mdx macrophages showed that CTLA4-Ig reduced expression of genes associated with leukocyte chemotaxis, migration, and extravasation; >90% of those affected genes were tumor necrosis factor-α target genes. Comparison of mdx and wild-type macrophages by RNA sequencing showed that 46% of the genes down-regulated by CTLA4-Ig were genes up-regulated in macrophages by the presence of muscular dystrophy in mice. These findings show that CTLA4-Ig is a promising immunotherapeutic for DMD, and many of its beneficial effects may result from direct actions on macrophages that modify their expression of proinflammatory genes.