A role for IL-33-activated ILC2s in eosinophilic vasculitis

Area of Science:

• Immunology
• Rheumatology
• Pulmonology

Background:

• Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare systemic vasculitis with unclear mechanisms.
• Elevated levels of thymic stromal lymphopoietin (TSLP), IL-25, and soluble ST2 (cytokine alarmins) are observed in EGPA patients.
• Reduced circulating type 2 innate lymphoid cells (ILC2s) in active EGPA suggest their involvement in disease.

Purpose of the Study:

• To investigate the role of ILC2s and related signaling pathways in EGPA pathogenesis.
• To establish and utilize a mouse model for studying EGPA mechanisms.
• To identify potential therapeutic targets for EGPA.

Main Methods:

• Measured serum cytokine levels (TSLP, IL-25, soluble ST2) and circulating ILC2s in EGPA patients.
• Developed a mouse model by administering IL-33 to predisposed, hypereosinophilic mice to induce vasculitis and pulmonary hemorrhage.
• Assessed the impact of ILC2 depletion and IL4Rα/STAT6 signaling blockade on disease development in the mouse model.

Main Results:

• EGPA patients exhibited elevated alarmins and reduced ILC2s.
• IL-33 administration induced vasculitis and pulmonary hemorrhage in mice, dependent on ILC2s and IL4Rα signaling.
• Blocking IL4Rα or STAT6 signaling reduced vascular leak, endothelial activation, and eosinophil migration in the mouse model.

Conclusions:

• IL-33, ILC2s, and IL4Rα signaling are implicated in EGPA pathogenesis.
• The developed mouse model provides a platform for further mechanistic studies of EGPA.
• These pathways represent potential targets for novel EGPA therapies.