Cytotoxic Response of CD4⁺ T Cells Orchestrated by SLAMF4 in Rheumatoid Arthritis

Area of Science:

• Immunology
• Rheumatology
• Cellular Biology

Background:

• Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint inflammation.
• CD4+ T cells play a critical role in RA pathogenesis.
• Signaling lymphocytic activation molecule family receptors (SLAMFs) are implicated in T cell activation and function.

Purpose of the Study:

• To investigate the role of SLAMFs in CD4+ T cell responses in RA.
• To identify specific CD4+ T cell subpopulations expressing SLAMFs that contribute to RA pathology.

Main Methods:

• Isolation of peripheral blood (PB) and synovial fluid (SF) mononuclear cells from RA patients.
• Multimodal approach including flow cytometry, RNA sequencing, and cell stimulation.
• High-dimensional unsupervised clustering and pathway enrichment analyses.

Main Results:

• SLAMF4+ effector memory CD4+ T cells (Tem) correlated with RA activity.
• SLAMF4+ CCR5+ Tem exhibited a cytotoxicity-related gene signature.
• SLAMF4high SAP+ CCR5+ Tem (Cytotox-F4high Tem) were identified as a distinct cytotoxic CD4+ T cell population in RA, present in SF.

Conclusions:

• Cytotox-F4high Tem represent a significant CD4+ cytotoxic T lymphocyte (CTL) subpopulation in RA.
• These cells are implicated in the pathogenesis of active RA.
• Targeting Cytotox-F4high Tem may offer a promising therapeutic strategy for RA.