THU0048 Stat3-Regulated Gene Expression in Circulating CD4+ T Cells Discriminates RA Patients Independently of Clinical Parameters in Early Arthritis: A Validation Study
Authors: A.G. Pratt, A.E. Anderson, N. Nair, J. Diboll, A. Skelton, D. Lendrem, B. Hargreaves, P.M. Brown, P. Stocks, A. Barton, J.D. Isaacs
Journal: Annals of the Rheumatic Diseases (2015)

<h3>Background</h3> Rheumatoid arthritis is a T cell mediated disease of immune dysregulation whose pathogenesis remains incompletely understood. We previously identified a 12-gene "signature", enriched for STAT3 target genes, which was predictive of rheumatoid arthritis (RA) in circulating CD4+ T cells of early arthritis patients<sup>1</sup>. Subsequent investigations have confirmed the importance of IL-6 mediated STAT3 signalling in circulating CD4+ T cells as an early event in RA pathogenesis<sup>2</sup>. <h3>Objectives</h3> To carry out an independent replication study, seeking to validate our previous findings with respect to a 12-gene expression signature in CD4+ T cells of early arthritis patients, interpreting the findings in the context of other clinically relevant baseline parameters. <h3>Methods</h3> Gene expression in highly purified peripheral blood CD4+ T cells from disease modifying anti-rheumatic drug (DMARD)- and steroid-naïve patients with suspected inflammatory arthritis was measured using Illumina microarray technology. A nested analysis focussed on normalised expression of those transcripts hybridised by the 12 probes identified during the previous study. Concurrent STAT3 pathway activation was determined in CD4+ T cells by paired whole blood flow cytometry, and detailed clinical and serological data were recorded for all participants. Analyses included the use of univariate tests, hierarchical clustering and logistic regression. <h3>Results</h3> In this independent cohort of 161 early arthritis patients, normalised expression of ten out of the 12 CD4+ T cell "signature" genes studied differed significantly between patients presenting with RA and alternative diagnoses (p&lt;0.05). Hierarchical clustering using the signature discriminated an RA-enriched subgroup of early arthritis patients. Differential expression was most pronounced for the STAT3-regulated genes PIM1, BCL-3 and SOCS3 (&gt;1.3-fold difference; p&lt;0.001 in each case), each of whose expression correlated strongly with paired CD4+ T cell intracellular phospho-STAT3. Multivariate analysis confirmed that the expression of each of these three genes predicted a diagnosis of RA independently of CRP, ESR, swollen joint count and age. <h3>Conclusions</h3> The regulation of gene expression by STAT3 in circulating CD4+ T cells is confirmed as an early event in RA pathogenesis. The functional relevance of this observation remains the subject of on-going in vitro investigation. <h3>References</h3> Pratt AG et al Ann Rheum Dis 2012; 2 Anderson AE et al Ann Rheum Dis 2015 <h3>Acknowledgements</h3> We thank research and clinical staff at Freeman Hospital, Newcastle upon Tyne, for their assistance in recruiting patients for this study, as well as the patients themselves for their generosity. <h3>Disclosure of Interest</h3> None declared