bioRxiv. 2024 Jan 26. pii: 2024.01.23.576771. [Epub ahead of print]
Benjamin Klein,
Mack B Reynolds,
Bin Xu,
Mehrnaz Gharaee-Kermani,
Yiqing Gao,
Celine C Berthier,
Svenja Henning,
Shannon N Loftus,
Kelsey E McNeely,
Amanda M Victory,
Craig Dobry,
Grace A Hile,
Feiyang Ma,
Jessica L Turnier,
Johann E Gudjonsson,
Mary X O'Riordan,
J Michelle Kahlenberg.
Photosensitivity is observed in numerous autoimmune diseases and drives poor quality of life and disease flares. Elevated epidermal type I interferon (IFN) production primes for photosensitivity and enhanced inflammation, but the substrates that sustain and amplify this cycle remain undefined. Here, we show that IFN-induced Z-DNA binding protein 1 (ZBP1) stabilizes ultraviolet (UV)B-induced cytosolic Z-DNA derived from oxidized mitochondrial DNA. ZBP1 is significantly upregulated in the epidermis of adult and pediatric patients with autoimmune photosensitivity. Strikingly, lupus keratinocytes accumulate extensive cytosolic Z-DNA after UVB, and transfection of keratinocytes with Z-DNA results in stronger IFN production through cGAS-STING activation compared to B-DNA. ZBP1 knockdown abrogates UV-induced IFN responses, whereas overexpression results in a lupus-like phenotype with spontaneous Z-DNA accumulation and IFN production. Our results highlight Z-DNA and ZBP1 as critical mediators for UVB-induced inflammation and uncover how type I IFNs prime for cutaneous inflammation in photosensitivity. One Sentence Summary: ZBP1 and mitochondrial Z-DNA drive autoimmune photosensitivity via cGAS-STING activation.