Stable gene expression of serial skin biopsies defines patient subsets in diffuse cutaneous systemic sclerosis. Homo sapiens

Systemic sclerosis (SSc) shows complex clinical manifestations including progressive skin and internal organ fibrosis. SSc can be divided into 'intrinsic subsets' by gene expression suggesting patient-specific heterogeneity in pathogenesis or temporal evolution of disease. Here we validate these subsets using an independent patient population, and test whether the genes vary over time with patients changing subsets as disease progresses, or if the genes are a stable feature of the patients within each subset. Skin biopsies were analyzed from 13 dSSc patients enrolled in an open label study of rituximab, 9 dSSc patients not treated with rituximab, and 9 healthy controls. These data recapitulate the patient 'intrinsic subsets' described previously with gene expression associated with cell proliferation, inflammatory processes, and a normal-like group. Serial skin biopsies showed consistent and non-progressing gene expression. We were unable to detect significant differences in gene expression before and after rituximab treatment, consistent with an apparent lack of clinical response. Serial biopsies from each patient stayed within the same gene expression subset regardless of treatment regimen or the time point at which they were taken. This demonstrates the intrinsic subsets are an inherent, reproducible and stable feature of SSc that is independent of disease duration. Overall design: Skin biopsies were analyzed from 13 dSSc patients enrolled in an open label study of rituximab, 9 dSSc patients not treated with rituximab, and 9 healthy controls.