IL-4 alters TLR7-induced B cell developmental program in lupus.

Area of Science:

• Immunology
• Autoimmunity
• B cell biology

Background:

• Toll-like receptor 7 (TLR7) stimulation drives autoantibody production in systemic lupus erythematosus (SLE) via specific B cell subsets.
• Double-negative 2 (DN2) B cells, characterized as T-bet+CD11c+IgD-CD27-, are key players in this pathogenic process.

Purpose of the Study:

• To investigate the therapeutic potential of Interleukin-4 (IL-4) in modulating TLR7-induced B cell responses in SLE.
• To determine how IL-4 affects the development and phenotype of B cells in the context of TLR7 activation.

Main Methods:

• Administration of IL-4 to autoimmune BXD2 mice treated with the TLR7 agonist R848.
• Single-cell transcriptomics analysis to assess B cell populations and gene expression.
• In vitro stimulation of SLE patient B cells with a DN2 polarizing cocktail and IL-4.

Main Results:

• IL-4 treatment significantly reduced autoantibodies and pathogenic T-bet+CD11c+IgD- B cells in mice.
• IL-4 redirected B cell development towards follicular, CD23+ germinal center (GC), and DN4-like memory B cells.
• IL-4 suppressed R848-induced GC B cell proliferation and reduced interferon response genes in SLE patient B cells.

Conclusions:

• IL-4 administration effectively counteracts TLR7-driven DN2 and GC B cell populations in SLE models.
• IL-4 promotes a developmental reprogramming of B cells, offering a potential therapeutic strategy for SLE.