Lupus dermal fibroblasts are pro-inflammatory and exhibit a pro-fibrotic phenotype in scarring skin disease

Fibroblasts are stromal cells known to regulate local immune responses important for wound healing and scar formation; however, the cellular mechanisms driving damage and scarring in cutaneous lupus erythematosus (CLE) patients remain poorly understood. Dermal fibroblasts in systemic lupus erythematosus (SLE) patients are abnormally exposed to cytokines, but the impact of inflammatory mediators on fibroblast responses in non-scarring versus scarring CLE subtypes is unclear. Here, we examined responses to cytokines in dermal fibroblasts from non-lesional skin of 22 SLE patients with CLE and 34 healthy controls. Notably, inflammatory cytokine responses were exaggerated in SLE fibroblasts compared to healthy controls. In lesional CLE biopsies, these same inflammatory profiles were reflected in single cell RNA sequencing of SFRP2+ and inflammatory fibroblast subsets, and TGF-β was identified as a critical upstream regulator for inflammatory fibroblasts in scarring discoid lupus lesions. In vitro cytokine stimulation of non-lesional fibroblasts from patients who scar from CLE identified an upregulation of collagens, particularly in response to TGF-β, whereas inflammatory pathways were more prominent in non-scarring patients. Our study revealed that SLE fibroblasts are poised to hyper-respond to inflammation, with differential responses among scarring versus non-scarring disease, providing a potential skin-specific target for mitigating damage.