BIOSAMPLES FROM VEDOSS PATIENTS SHOW CLASSIC PATHOLOGICAL SIGNS OF SCLERODERMA:OPPORTUNITY FOR A BIOLOGICAL DIAGNOSIS OF DISEASE

R. Ross, E. Clarke, W. Merchant, B. Caballero-Ruiz, I. Georgiou, A. Carriero, G. Abignano, A. Herrick, C. P. Denton, N. Riobo-Del Galdo, F. Del GaldoUniversity of leeds, LIRMM, Leeds, United Kingdom Leeds Teaching Hospitals, Chapel Allerton Hospital, NIHR Leeds Biomedical Research Centre, Leeds, United Kingdom University of leeds, Division of Pathology and Data Analytics, Leeds, United Kingdom Leeds Teaching Hospitals NHS Trust, Department of Histopathology, Leeds, United Kingdom San Carlo Hospital of Potenza, Rheumatology Institute of Lucania (IReL) and Rheumatology Department of Lucania, Potenza, Italy University of Manchester, Division of Musculoskeletal & Dermatological Sciences, Manchester, United Kingdom UCL, Division of Medicine, London, United Kingdom university of leeds, School of Molecular and Cellular Biology, Leeds, United Kingdom  Background The five-year analysis of the EUSTAR multicentre prospective study for Very Early Diagnosis Of Systemic Sclerosis (VEDOSS) has recently indicated that RP patients with one more VEDOSS criteria have an increased risk of SSc progression, indicating a window of opportunity for early detection of SSc and clinical and therapeutic intervention. Furthermore, it warrants further evaluation of VEDOSS biosamples to enhance our understanding of SSc pathogenesis. Objectives Here we aimed to determine whether sera, skin or dermal fibroblasts cultured from VEDOSS patients showed any biological hallmark of SSc. Methods Sixty-four VEDOSS sera samples were tested for expression of IFN inducible chemokines (CXCL-9,10 and 11 and CCL2, 8 and 19) and biomarker of extracellular matrix turnover (ELF test). 3mm skin biopsies were taken from the forearms from 11 skin biopsies from the forearm of VEDOSS patients and 5 healthy controls and 6 SSc patients. Biopsies was subjected to histology analysis, including haematoxylin and eosin (H&E) and masson trichrome (MT) staining and immunohistological staining (IHC) for CD45, pSTAT1 and MX1. In addition, 7 VEDOSS skin biopsies, along with 2 healthy control and 3 SSc, were used to explant fibroblasts cell lines. mRNA and protein were isolated from primary fibroblasts and processed for RT-qPCR and western blotting analyses and collagen gel contractability assessed. Results Sera from VEDOSS patients showed significantly higher IFN-inducible chemokines compared to HC and an intermediate levels compared to SSc [Mean (STDV) HC= 4.69(0.29) vs. VEDOSS= 4.93 (0.39); SSc= 5.30 (0.54)]. ELF score was within normal range for most patients with VEDOSS and showed no statistical difference to HC. Skin biopsies from VEDOSS patients showed evidence of fibrosis and increased collagen bundles within the dermis evidenced in H&E and MT staining, as usually seen in SSc, compared to HC. IHC showed increased number of CD45+ cells in VEDOSS. Semiquantitative analysis of histopathological samples indicated a significant correlation between MT and CD45 staining for VEDOSS (R=0.8828 P=0.0016). In vitro, fibroblasts from VEDOSS patients showed an average 5-fold higher collagen mRNA levels compared to HC fibroblasts, at a similar range to that seen in SSc fibroblasts, confirmed at protein level via western blotting. Furthermore, VEDOSS fibroblasts induced greater gel contraction compared to HC. Conclusion Although pilot in nature, this study suggests that patients with no clinical signs of skin fibrosis in their forearms already show biomarker signs of SSc both in their sera, skin biopsies and fibroblast level. Our data indicate that skin thickening is a late manifestation of SSc pathogenesis and early window of opportunity of patients with VEDOSS could be targeted for immune intervention and antifibrotic intervention. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests Rebecca Ross: None declared, Emily Clarke: None declared, Will Merchant: None declared, Begoña Caballero-Ruiz: None declared, Ioanna Georgiou: None declared, Antonio Carriero: None declared, Giuseppina Abignano: None declared, Ariane Herrick Consultant of: ALH has undertaken consultancy work for Boehringer-Ingelheim, Gesynta, Camurus and CSL Behring, has received research funding from Actelion and Gesynta, and has received speaker’s fees from Actelion., Grant/research support from: ALH has undertaken consultancy work for Boehringer-Ingelheim, Gesynta, Camurus and CSL Behring, has received research funding from Actelion and Gesynta, and has received speaker’s fees from Actelion., Christopher P Denton Consultant of: Chris Denton, PhD, FRCP has served as an advisor or consultant for: Actelion Pharmaceuticals, Biogen Idec, CSL Behring, GSK, Inventiva, MedImmune Inc., Merck, Roche, and Takeda and has served as a speaker or a member of a speakers bureau for Actelion Pharmaceuticals, CSL Behring, GSK, and Novartis Pharmaceuticals., Natalia Riobo-Del Galdo: None declared, Francesco Del Galdo Consultant of: F.D.G. has received research funding and/or consulting fees or other remuneration from GlaxoSmithKline, AstraZeneca, Boehringer Ingelheim, Actelion, Capella Bioscience, Chemomab, Kymab, Actelion, iqvia, and Mitsubishi Tanabe, Grant/research support from: F.D.G. has received research funding and/or consulting fees or other remuneration from GlaxoSmithKline, AstraZeneca, Boehringer Ingelheim, Actelion, Capella Bioscience, Chemomab, Kymab, Actelion, iqvia, and Mitsubishi Tanabe. Keywords: Systemic sclerosis, Autoantibodies, Cytokines and chemokines DOI: 10.1136/annrheumdis-2023-eular.3157Citation: , volume 82, supplement 1, year 2023, page 294Session: Pathogenic pathways in Systemic Sclerosis and Myositis (Poster Tours)