<scp>LL37</scp>‐<scp>DNA</scp> Complex Drives Vitiligo Progression Through <scp>TLR9</scp>‐<scp>MyD88</scp> Signaling Pathways

Vitiligo is an autoimmune disorder characterized by chronic depigmentation and milk-white patches on the skin. Skin infiltration by autoreactive CD8⁺ T cells causes melanocyte destruction in vitiligo. Multiple risk factors, particularly immune-related inflammatory factors, are involved in the disappearance of melanocytes. LL37 is a classic damage-associated molecular pattern molecule that is involved in the development of various autoimmune diseases. An enhanced expression of LL37 in vitiligo is known; however, the exact role of LL37 in melanocyte loss has not yet been elucidated. In the present study, we detected increased LL37 expression in vitiligo serum and lesions. Furthermore, we confirmed that cultured keratinocytes released LL37 after treatment with H₂O₂. Moreover, the LL37-DNA complex enhanced the secretion of CXCL9, CXCL10, and CXCL16 from keratinocytes via the TLR9-MyD88 signaling pathway and facilitated the migration of CD8⁺ T cells. Altogether, our study demonstrates that LL37 released from keratinocytes binds to DNA and contributes to melanocyte destruction under oxidative stress-induced autoimmunity in vitiligo.