Phospho-STAT1/3 and Gene Expression Measurement in Circulating CD4+ T Cells As Diagnostic Tools in Early Autoantibody-Negative Rheumatoid Arthritis

Amy E. Anderson¹, Arthur G Pratt¹, Mamdouh Sedhom², Nisha Nair³, Jonathan Massey³, Christine Routledge¹, Ben Hargreaves¹, Philip Brown¹, Anne Barton⁴, John D Isaacs¹ and Ranjeny Thomas², ¹Institute of Cellular Medicine (Musculoskeletal Research Group), NIHR Newcastle Biomedical Research Centre, Newcastle Hospitals Foundation Trust and Newcastle University, Newcastle upon Tyne, United Kingdom, ²Translational Research Institute, The University of Queensland Diamantina Institute, Queensland, Australia, ³NIHR Manchester Musculoskeletal Biomedical Research Unit, Manchester Academy of Health Sciences, Manchester, United Kingdom, ⁴NIHR Manchester Musculoskeletal Biomedical Research Unit, Manchester Academic Health Science Centre, Manchester, United Kingdom

Meeting: 2014 ACR/ARHP Annual Meeting

Keywords: biomarkers and diagnosis, Early Rheumatoid Arthritis, Gene Expression, T cells

Session Information

Title: Rheumatoid Arthritis - Human Etiology and Pathogenesis

Session Type: Abstract Submissions (ACR)

Background/Purpose

Early diagnosis of rheumatoid arthritis (RA) improves outcomes but is challenging, particularly amongst anti-citrullinated peptide auto-antibody (ACPA) negative individuals. Previously we identified an IL-6 mediated CD4⁺T cell transcriptional signature, enriched for signal transduction and activation of transcription-3 (STAT3) target genes, which had discriminatory value for this purpose. In the present work we sought a more readily applicable diagnostic assay, and insight into mechanisms of disease induction.

Methods

Amongst early arthritis patients and controls naïve to immunomodulatory treatment, constitutive and IL-6-induced expression of phosphorylated STAT1 and 3 (pSTAT1/3) were determined in circulating lymphocytes using flow cytometry. Contemporaneous serum cytokine levels were measured using a validated, highly sensitive immuno-assay, and normalised CD4⁺T cell gene expression of the previously described STAT3 target gene-enriched signature was determined using microarray.

Results

In 187 early arthritis patients, constitutive pSTAT3 correlated with serum IL-6 levels maximally in CD4⁺ T cells, compared with other circulating leukocyte subsets. Increased constitutive pSTAT3, but not pSTAT1, was observed in circulating CD4⁺ T cells of early ACPA negative RA patients compared with disease controls. Amongst patients presenting with undifferentiated arthritis (UA) the ratio of constitutive pSTAT3:pSTAT1 in CD4⁺ T cells could be incorporated into an algorithm for predicting progression to classifiable RA with high accuracy (area under ROC curve = 0.91; p<0.001). The comparable utility of the previously described CD4⁺T cell gene signature as a discriminatory tool, and the accuracy of pSTAT3:pSTAT1 as a surrogate for target gene expression, are the subject of on-going analyses.

Conclusion

Our findings support a particular role for IL-6-driven CD4⁺ T cell activation via STAT3 during the induction of RA, which may be of particular importance in the pathogenesis of ACPA-negative disease. CD4⁺ pSTAT measurements show promise as biomarkers of progression to RA in sero-negative UA.

Disclosure:

A. E. Anderson,
None;

A. G. Pratt,

Pfizer Inc,

M. Sedhom,
None;

N. Nair,
None;

J. Massey,
None;

C. Routledge,
None;

B. Hargreaves,
None;

P. Brown,
None;

A. Barton,
None;

J. D. Isaacs,

Pfizer Inc,

R. Thomas,
None.

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