Constitutively CD40-activated B cells regulate CD8 T cell inflammatory response by IL-10 induction.

Area of Science:

• Immunology
• Inflammation Research
• T cell Biology

Background:

• B cells encounter high CD40 ligand (CD40L) levels in chronic inflammation.
• B cells expressing both CD40 and CD40L are found in autoimmune diseases and lymphoma.
• The impact of constitutively CD40-activated B cells on T cell responses is not well understood.

Purpose of the Study:

• To investigate how B cells with autocrine CD40/CD40L signaling affect T cell responses.
• To determine if CD40L-expressing B cells can modulate T cell-mediated inflammation.

Main Methods:

• Utilized a mouse model where B cells express a CD40L transgene (CD40LTg).
• Examined T cell activation, cytokine production (IL-10, IL-17, IFN-γ), and disease regulation.
• Employed adoptive transfer of naive CD8 T cells and CD40LTg B cells in RAG-1(-/-) mice to induce and study colitis.

Main Results:

• CD40LTg B cells stimulated CD4 and CD8 T cells to produce IL-10, dependent on IFN-I and PD-1.
• This IL-10 induction by CD8 T cells was crucial for counterregulating T cell overactivation.
• Cotransfer of CD40LTg B cells, but not wild-type B cells, reduced IL-17 responses and ameliorated colitis by inducing IL-10 in CD8 T cells.

Conclusions:

• B cells expressing CD40L possess the capacity to induce IL-10 production in CD8 T cells.
• This mechanism suggests a therapeutic potential for CD40L-expressing B cells in managing inflammatory CD8 T cell responses.
• Targeting CD40L-expressing B cells may offer a novel strategy for treating inflammatory diseases driven by aberrant T cell activity.