Silica Exposure Differentially Modulates Autoimmunity in Lupus Strains and Autoantibody Transgenic Mice

Area of Science:

• Immunology
• Toxicology
• Autoimmunity

Background:

• Inhalational exposure to crystalline silica is linked to autoimmune diseases.
• Mechanisms by which silica induces autoantibodies are poorly understood.
• Silica's impact on B cell tolerance requires further investigation.

Purpose of the Study:

• To investigate how silica lung exposure breaks B cell tolerance.
• To understand the mechanisms of silica-induced autoantibody production.
• To analyze the fate of autoreactive B cells following silica exposure.

Main Methods:

• Exposure of wildtype and lupus-prone mice (including autoantibody transgenic models) to instilled silica or vehicle.
• Monitoring of lung injury, autoimmunity, and B cell fate.
• Utilizing a unique autoantibody transgene reporter system for in vivo tracking.

Main Results:

• Silica exposure induced lung damage and pulmonary lymphoid aggregates in all mouse strains.
• Central B cell tolerance (deletion and anergy) remained intact despite silica exposure.
• Silica-exposed splenocytes showed increased autoantibody production upon Toll-like receptor (TLR) stimulation.

Conclusions:

• Silica exposure does not overtly disrupt central B cell tolerance.
• Silica may subvert tolerance at alternative checkpoints or require co-exposures.
• Lung injury from silica may subtly alter autoreactive B cell regulation, unmasked by TLR ligands.