Gene Expression Signatures in Inflammatory and Sclerotic Morphea Skin and Sera Distinguish Morphea from Systemic Sclerosis

Abstract

Morphea is an inflammatory fibrotic disorder of the skin that has been likened to systemic sclerosis (SSc). We sought to examine the molecular landscape of morphea by examining lesional skin gene expression and blood biomarkers and comparing the gene expression profiles with those from site-matched nonlesional and SSc lesional skin. We found the morphea transcriptome is dominated by IFN-γ-mediated T helper 1 immune dysregulation, with a relative paucity of fibrosis pathways. Specifically, expression profiles of morphea skin clustered with the SSc inflammatory subset and were distinct from the those of SSc fibroproliferative subset. Unaffected morphea skin also differed from unaffected SSc skin because it did not exhibit pathological gene expression signatures. Examination of downstream IFN-γ-mediated chemokines, CXCL9 and CXCL10, revealed increased transcription in the skin but not in circulation. In contrast to transcriptional activity, CXCL9 was elevated in serum and was associated with active, widespread cutaneous involvement. Taken together, these results indicate that morphea is a skin-directed process characterized by T helper 1 immune-mediated dysregulation, which contrasts with fibrotic signatures and systemic transcriptional changes associated with SSc. The similarity between morphea and the inflammatory subset of SSc on transcriptional profiling indicates that therapies under development for this subset of SSc are also promising for treatment of morphea.