Markers of Type 2 Inflammation and Immunosenescence Are Upregulated in Localized Scleroderma

Localized scleroderma (LS) is an autoimmune, fibrotic skin disease that is thought to be triggered by environmental factors. Recent evidence from systemic autoimmune diseases proposed that the induction of immunosenescence may link environmental triggers with autoimmunity development. We aimed to explore the inflammatory signature in juvenile LS and investigate the presence of DNA instability and immunosenescence using publicly available transcriptomic data. High-throughput RNA sequencing data from 28 juvenile LS and 10 healthy controls were analyzed. Unsupervised clustering, pathway analyses, cell-type enrichment, fusion analyses, and immunosenescence gene set enrichment were performed. IFN and Type 1/2/3 pathways were upregulated in clinically active and histologically inflammatory LS. Type 2 inflammatory signature in both inflammatory and fibrotic LS was demonstrated by enriched genes, pathways, and deconvolution analyses (eosinophils). Features of genotoxic stress signals manifesting as DNA instability genes, pathways, and fusion events as well as mitochondrial dysfunction were demonstrated for the first time in LS. Features of immunosenescence (e.g., the upregulation of pathways involved in T cell exhaustion, inhibitory receptors, and cellular senescence and the enrichment of senescent genes) were also confirmed in (active and inflammatory) LS. Immunosenescence and inflammaging may underlie the complex and heterogeneous nature of immune responses seen in LS and should be further studied.