FRI0420 Altered transcriptome of circulating cd14+ monocytes in systemic sclerosis

Background Previous studies indicated monocyte-derived cells as important players in the development of multiple organ fibrosis. Although changes in monocyte’s phenotypes as well as an increased infiltration into fibrotic organs were reported in systemic sclerosis (SSc), the detailed role of these cells in multi-organ fibrogenesis remains unclear. Objectives We aimed to characterise a contribution of circulating CD14+ monocytes in the disease course in limited cutaneous (lc) and diffuse cutaneous (dc) SSc. Methods CD14+ monocytes were isolated from peripheral blood of lcSSc (n=5, age=54.4±6.7), dcSSc patients (n=5, age=51.8±7.2) and age- and sex-matched healthy controls (HC) (n=5, age=50.8±9.7). Total RNA was isolated and polyA libraries were prepared using TruSeq Stranded mRNA kit. Next Generation Sequencing was performed using Illumina HiSeq 4000 platform. Differentially expressed genes were computed using DeSEQ2 algorithm. Principal Component Analysis (PCA) was accomplished as well as pathway analysis using Metacore software. mRNA levels of top targets were confirmed by qPCR. Results We detected 1440 differentially expressed genes between dcSSc vs HC and 225 between lcSSc and HC respectively (p≤0.01; log2 ratio ≥0.5, figure 1). Among those, in dcSSc 1076 were upregulated (e.g. MMP9, IL1R2, FLT3, MIF, TLR9) and 364 were downregulated (e.g. TGFBR1, CD44, CD244, HLA-DRA, HLA-G). In lcSSc 160 transcripts were upregulated (e.g. CCL2, WNT5B, MMP17) and 65 were downregulated (e.g. KLF11, IRAK2). We identified 123 commonly deregulated genes between SSc subgroups (e.g. CCL3, CD14, IL27, MMP17). Principal component analysis showed close clustering within SSc subgroups and clear separation from healthy controls. Pathway analysis revealed alterations in several biological processes important in fibrogenesis including antigen presentation, MIF-induced immune responses, TGF-β, NOTCH and WNT signalling pathways. qPCR analysis further confirmed differences in gene expression on mRNA level (n HC=8, n SSc=25, p≤0.05). Conclusions To our knowledge, this is the first global transcriptome analysis of peripheral blood CD14+ monocytes in SSc. Our results suggest an initial activation of monocytes in peripheral blood, which might be further translated into novel cellular biomarker of the disease and potentially used for distinguishing between responders and non-responders to a novel treatment in future clinical trials. Disclosure of Interest M. Rudnik: None declared, M. Stellato: None declared, P. Blyszczuk: None declared, O. Distler Grant/research support from: Actelion, Bayer, Boehringer Ingelheim, Mitsubishi Tanabe Pharma and Roche, Consultant for: Actelion, Bayer, BiogenIdec, Boehringer Ingelheim, ChemomAb, espeRare foundation, Genentech/Roche, GSK, Inventiva, Italfarmaco, Lilly, medac, MedImmune, Mitsubishi Tanabe Pharma, Pharmacyclics, Novartis, Pfizer, Sanofi, Sinoxa and UCB, G. Kania Grant/research support from: Bayer Pharma AG, Actelion