Pyroptotic Keratinocytes and Sebocytes Promote Neutrophil Extracellular Trap Formation Through HMGB1 in EGFR ‐ TKI ‐Associated Secondary Eczematous Rash and Acneiform Rash

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) therapy is frequently complicated by xerosis, secondary eczematous rash and acneiform rash. Mechanistically, EGFR-TKIs have been shown to trigger pyroptotic cell death in epidermal keratinocytes and sebocytes. We investigated whether the pyroptosis-associated release of high-mobility group box 1 (HMGB1) promotes neutrophil extracellular trap (NET) formation in EGFR-TKI-related skin toxicities. Skin and plasma samples were collected from EGFR-TKI-treated patients with no skin toxicity, xerosis, secondary eczematous rash, acneiform rash, or combined phenotypes. HMGB1 localization and expression, along with NET markers, were assessed by immunohistochemistry, immunofluorescence, ELISA and Western blot. Human neutrophils were stimulated with supernatants from afatinib-induced pyroptotic HaCaT and SZ95 cells (wild-type, gasdermin E-knockdown or HMGB1-knockdown) or with recombinant HMGB1. NETs were quantified by immunofluorescence and ELISA. Skin samples from affected patients exhibited nuclear-to-cytoplasmic translocation of HMGB1 in keratinocytes and/or sebocytes, accompanied by increased acetylated HMGB1 levels and elevated plasma HMGB1 concentrations. Cytoplasmic HMGB1 positivity correlated with dermal neutrophil infiltration, and plasma HMGB1 levels showed a positive association with peripheral neutrophils. NETs were more prominently detected in samples from patients with secondary eczematous rash and acneiform rash. Supernatants derived from pyroptotic HaCaT and SZ95 cells strongly induced NET formation, an effect significantly diminished by inhibition of pyroptosis or HMGB1 expression and rescued by the exogenous of recombinant HMGB1. Collectively, our findings demonstrate that a pyroptosis-HMGB1-NET axis drives EGFR-TKI-associated acneiform and secondary eczematous eruptions, highlighting HMGB1 and NETosis as promising therapeutic targets to mitigate skin toxicities.