B cell autophagy mediates TLR7-dependent autoimmunity and inflammation

Area of Science:

• Immunology
• Autoimmunity
• Cell Biology

Background:

• Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by loss of B cell self-tolerance and autoantibody production.
• Overexpression of toll-like receptor 7 (TLR7) is implicated in SLE pathogenesis.
• The role of autophagy in TLR7-mediated B cell activation in SLE is not well understood.

Purpose of the Study:

• To investigate the role of autophagy in TLR7-dependent B cell activation and SLE induction.
• To determine if ablating autophagy in B cells can prevent or reverse SLE development.

Main Methods:

• Compared SLE development in Tlr7 transgenic (Tg) mice with and without B cell-specific ablation of autophagy (Cd19-Cre Atg5(f/f)).
• Assessed hallmarks of SLE including antinuclear antibodies (ANA), inflammation, glomerulonephritis, and survival rates.
• Measured serum cytokine levels and extramedullary hematopoiesis (EMH).

Main Results:

• Absence of B cell autophagy eliminated ANA production and inflammation, curing SLE in Tlr7 Tg mice.
• Autophagy-deficient mice showed significantly extended survival compared to Tlr7.1 Tg mice.
• Glomerulonephritis was ameliorated, and cytokine levels were similar to controls in autophagy-deficient mice.

Conclusions:

• B cells require an autophagy-dependent mechanism for TLR7-mediated priming to induce SLE.
• Targeting autophagy in B cells presents a potential therapeutic strategy for SLE.
• Hyper-IgM production and anemia in Tlr7.1 Tg mice may involve alternative pathways independent of B cell autophagy.