Single cell spatial proteomics identifies JAK/STAT pathway as actionable therapeutic target in toxic epidermal necrolysis

Toxic epidermal necrolysis (TEN) is a fatal cutaneous adverse drug reaction and an emerging public health issue 1-3. Triggered by common medications, patients suffer from fulminant epidermal detachment and long-term sequalae. Although molecular mechanisms driving keratinocyte cytotoxicity have been reported, no effective therapy exists4-6. In recent years, powerful omics technologies have expanded into spatial context and we reasoned that single cell spatial proteomics could uncover novel therapeutic targets in TEN. Applying Deep Visual Proteomics7,8 to formalin fixed paraffin embedded archived skin-tissue biopsies of three types of cutaneous drug reactions with varying severity quantified over 5,000 proteins in keratinocytes and skin-infiltrating immune cells. Most strikingly, this revealed a robust enrichment of Type-I- and -II interferon signature in the immune cell and keratinocyte compartment of TEN patients, along with a drastic activation of pSTAT1. Targeted inhibition with pan-JAK inhibitor (JAKi) Tofacitinib reduced keratinocyte-directed cytotoxicity in a novel live-cell imaging assay, using patient-derived keratinocytes and PBMCs. Furthermore, oral administration of pan-JAKi Tofacitinib or Baricitinib ameliorated clinical and histological disease severity in two distinct mouse models of TEN. This study uncovers the JAK-STAT and interferon signaling pathways as key pathogenic drivers of TEN and demonstrates the potential of targeted JAK inhibition as a curative therapy.