B cell-derived IL-10 does not regulate spontaneous systemic autoimmunity in MRL.Fas(lpr) mice

Area of Science:

• Immunology
• Autoimmunity
• Cell Biology

Background:

• B cells play a dual role in autoimmune diseases like systemic lupus erythematosus (SLE), contributing to pathogenesis and regulation via IL-10.
• The concept of regulatory B cells (Bregs) secreting IL-10 is debated, impacting the understanding of B cell-targeted therapies.

Purpose of the Study:

• To investigate the significance of B cell-secreted IL-10 in spontaneous autoimmunity, specifically in a murine lupus model.
• To determine if IL-10 produced by B cells effectively suppresses self-reactive immune responses and disease severity in lupus.

Main Methods:

• Lineage-specific deletion of the Il10 gene in B cells of lupus-prone mice.
• Genetic marking to identify IL-10-transcribing cells.
• Analysis of B cell subsets (e.g., CD1d(hi)CD5(+), CD21(hi)CD23(hi)) for IL-10 transcription.

Main Results:

• B cell-derived IL-10 was ineffective in suppressing spontaneous activation of self-reactive B and T cells in lupus.
• Deletion of Il10 from B cells did not alter disease severity or survival rates in mice.
• CD4 T cells and macrophages, not B cells, were the dominant IL-10-producing cell populations.
• IL-10 transcription in B lineage cells was rare and primarily observed in short-lived plasmablasts, suggesting an activation-driven phenotype.

Conclusions:

• IL-10-dependent B cell regulation does not restrain disease in this spontaneous murine lupus model.
• The pathogenic effects of B cells in lupus are not significantly counterbalanced by their IL-10-dependent regulatory functions.
• The role of Bregs in spontaneous autoimmunity may be overestimated, with other immune cells being more critical for IL-10 production.