E4BP4 restrains effector-memory CD8⁺ T cell responses in systemic lupus erythematosus

Area of Science:

• Immunology
• Molecular Biology
• Autoimmunity

Background:

• CD8+ T cells drive tissue injury in systemic lupus erythematosus (SLE).
• Transcriptional regulation of pathogenic CD8+ T cell differentiation is poorly understood.
• Cytotoxic memory CD8+ T cell populations contribute to chronic inflammation in SLE.

Purpose of the Study:

• Identify transcriptional mechanisms controlling pathogenic CD8+ T cell differentiation in lupus.
• Investigate the role of transcription factor E4BP4 (NFIL3) in regulating CD8+ T cell responses.
• Determine E4BP4's function in maintaining immune homeostasis during autoimmunity and infection.

Main Methods:

• Analysis of E4BP4 expression in CD8+ T cells from SLE patients.
• Utilizing a lupus-like disease mouse model with E4BP4 deficiency.
• CD8+ T cell depletion studies and competitive adoptive transfer experiments.
• Investigating CD8+ T cell responses following Listeria monocytogenes infection.

Main Results:

• E4BP4 expression is reduced in SLE patients' CD8+ T cells and correlates with disease activity.
• E4BP4 deficiency exacerbates lupus-like disease, increasing autoantibodies, immune complex deposition, and renal pathology.
• E4BP4 deficiency leads to systemic accumulation of cytotoxic effector-memory CD8+ T cells.
• E4BP4 functions cell-intrinsically to limit CD8+ T cell cytotoxicity and proliferation in autoimmunity.
• E4BP4 deficiency enhances CD8+ effector-memory T cell responses to Listeria monocytogenes infection.

Conclusions:

• E4BP4 acts as a critical transcriptional checkpoint restricting pathogenic CD8+ effector-memory T cell responses.
• E4BP4 is essential for maintaining immune homeostasis in both autoimmune diseases and infections.
• Targeting E4BP4 may offer therapeutic strategies for controlling aberrant CD8+ T cell-mediated immunopathology.