Precise identification and tracking of HMGCR-reactive CD4+ T cells in the target tissue of patients with anti-HMGCR immune-mediated necrotising myopathy

Eleni Tiniakou; Alex Girgis; Tiara Siafei; Jemima Albayda; Brittany Adler; Julie J Paik; Christopher A Mecoli; Alison Rebman; Mark J Soloski; Lisa Christopher-Stine; Kellie N Smith; Antony Rosen; Andrew Lee Mammen; Erika Darrah

doi:10.1136/ard-2024-225732

Precise identification and tracking of HMGCR-reactive CD4+ T cells in the target tissue of patients with anti-HMGCR immune-mediated necrotising myopathy

Ann Rheum Dis. 2024 Oct 11:ard-2024-225732. doi: 10.1136/ard-2024-225732. Online ahead of print.

Authors

Eleni Tiniakou¹, Alex Girgis^{2

3}, Tiara Siafei², Jemima Albayda², Brittany Adler², Julie J Paik², Christopher A Mecoli², Alison Rebman², Mark J Soloski², Lisa Christopher-Stine², Kellie N Smith⁴, Antony Rosen², Andrew Lee Mammen^#^{2

5

6}, Erika Darrah^#²

Affiliations

¹ Division of Rheumatology, Johns Hopkins University, School of Medicine, Baltimore, MD, USA [email protected].
² Division of Rheumatology, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
³ Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
⁴ Department of Oncology and the Bloomberg-Kimmel Institute for Cancer Immunotherapy and Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
⁵ NIAMS/NIH, Bethesda, Maryland, USA.
⁶ Division of Neurology, Johns Hopkins University, School of Medicine, Baltimore, MS, USA.

^# Contributed equally.

PMID: 39393845
DOI: 10.1136/ard-2024-225732

Abstract

Background: Anti-3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR)-positive immune-mediated necrotising myopathy (IMNM) is characterised by the presence of IgG autoantibodies against HMGCR and a strong association with specific HLA-DR alleles. Although these findings implicate HMGCR-specific CD4⁺T-cells in the disease's pathogenesis, no such cells have been described. In this study, we aimed to identify and characterise HMGCR-reactive CD4⁺T-cells and assess their presence in affected muscle tissue from patients with anti-HMGCR+IMNM.

Methods: Peripheral blood mononuclear cells from patients with anti-HMGCR+IMNM (n=10) and dermatomyositis (DM; n=10) were stimulated with HMGCR protein and peptides identified using a natural antigen processing assay (NAPA; n=6). CD4⁺T-cell activation was assessed by CD154 upregulation via flow cytometry. T-cell receptor β(TCR) sequencing was performed on paired HMGCR-reactive T-cells and muscle biopsy tissue (n=5).

Results: CD4⁺T-cell responses to HMGCR protein were higher in patients with anti-HMGCR+IMNM compared with DM (median 0.06 vs 0.00, p=0.0059). These responses were enriched in Th1-Th17 cells, and when present, they positively correlated with anti-HMGCR antibody levels (r²=0.89, p=0.0012). NAPA revealed convergent presentation of seven HMGCR core peptides, with substantial overlap in the peptide repertoires between patients. These HMGCR peptides elicited robust CD4⁺T-cell responses, with 9/10 anti-HMGCR+IMNM patients responding to at least one peptide, compared with 1/10 DM (p=0.0003). Analysis of HMGCR-reactive TCRs β yielded antigen-reactive motifs that were enriched in muscle biopsies (projection score 0.03 vs 0.63, p=0.007).

Conclusion: HMGCR-antigen-reactive CD4⁺T-cells are present in the circulation and target tissue of patients with anti-HMGCR+IMNM, suggesting an active role for these cells in the pathogenesis of anti-HMGCR+IMNM.

Keywords: Autoimmunity; Polymyositis; T-Lymphocytes.

Abstract

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