STAT6 suppression prevents bleomycin-induced dermal fibrosis

Area of Science:

• Immunology
• Dermatology
• Molecular Biology

Background:

• Systemic sclerosis (SSc) is characterized by skin and organ fibrosis.
• Interleukins (IL)-4 and IL-13 are implicated in SSc pathogenesis, promoting collagen production.
• Signal transducer and activator of transcription 6 (STAT6) is a key downstream mediator of IL-4 and IL-13 signaling.

Purpose of the Study:

• To investigate the role of STAT6 in the pathogenesis of skin fibrosis in SSc.
• To determine if STAT6 activation correlates with SSc severity.
• To evaluate STAT6 inhibition as a potential therapeutic strategy for SSc-related fibrosis.

Main Methods:

• Assessed STAT6 phosphorylation in SSc patient skin biopsies and bleomycin-induced mouse models.
• Utilized Stat6 knockout mice and a STAT6 inhibitor (AS1517499) to assess antifibrotic effects.
• Conducted co-culture experiments with skin epithelial cells and fibroblasts to elucidate STAT6-mediated signaling pathways.

Main Results:

• Elevated STAT6 phosphorylation was observed in fibrotic skin from SSc patients and bleomycin-treated mice.
• Stat6 knockout mice exhibited suppressed fibrotic cytokine expression, reduced collagen/fibronectin production, and attenuated skin fibrosis and inflammation.
• STAT6 inhibition and knockdown demonstrated significant reduction in fibrotic markers and inflammation in both in vivo and in vitro models.

Conclusions:

• STAT6 plays a critical role in driving skin fibrosis in SSc.
• STAT6 mediates fibrosis by promoting innate inflammation and alternatively activated macrophage differentiation.
• Targeting STAT6 presents a promising therapeutic avenue for treating systemic sclerosis.