Lymphocyte immunophenotyping in inflammatory myositis: a review

Area of Science:

• Immunology
• Autoimmune Diseases
• Cell Biology

Background:

• Idiopathic inflammatory myopathies (IIM) are a group of rare autoimmune diseases characterized by chronic muscle inflammation.
• The pathogenesis of IIM is complex and involves dysregulation of the immune system, with various immune cell types implicated.

Purpose of the Study:

• To review the current knowledge on immune cell phenotypes in idiopathic inflammatory myopathies (IIM).
• To highlight the specific T cell and B cell subpopulations involved in different IIM subsets.
• To discuss the implications of these findings for diagnosis and therapeutic targeting.

Main Methods:

• This is a comprehensive review of existing literature on immune cell phenotypes in IIM.
• Analysis of published data on circulating and muscle-infiltrating immune cells, including T cells (CD4+, CD8+, Treg, Tfh) and B cells (plasma cells, Bregs).

Main Results:

• T cell subset imbalances are consistently observed in IIM, with variations across disease subtypes (e.g., CD4+ T cells in dermatomyositis, CD8+ T cells in polymyositis/inclusion body myositis).
• Novel proinflammatory T cell subsets (CD8+Tbet+, CD28-) and impaired regulatory T cells (Treg) are identified.
• B cell compartment abnormalities, including increased plasma cells and decreased regulatory B cells (Bregs), are reported in various IIM forms.

Conclusions:

• Immune cell abnormalities are diverse and specific to different IIM subsets, reflecting the heterogeneity of these conditions.
• Detailed immunophenotyping of B cells and T cells in IIM may lead to improved diagnostic strategies.
• Understanding these immune cell profiles can help identify novel therapeutic targets for IIM.