OP0011 HIGHLY DIFFERENTIATED CD4 AND CD8 T EFFECTOR MEMORY CELLS RE-EXPRESSING CD45RA (TEMRA) ARE ASSOCIATED WITH ACTIVE DISEASE REFRACTORY TO ANTI-TNF THERAPY IN RHEUMATOID ARTHRITIS

Abstract

BackgroundHighly differentiated T cells have been reported to be enriched in rheumatoid arthritis (RA) compared to healthy individuals1. The role of terminally differentiated T effector memory re-expressing CD45RA (Temra) in RA pathogenesis and disease activity is still unclear, including whether they can be used as a marker of sustained disease activity in RA patients receiving anti-TNF therapy.ObjectivesTo investigate whether the frequency of peripheral blood Temra can be used as a biomarker to identify disease refractory to anti-TNF therapy in RA, if they correlate with inflammation in anti-TNF treated patients, and whether they associate with a flare following tapering anti-TNF.MethodsRA patients on anti-TNF therapy were recruited from rheumatology clinic (cross-sectional cohort). Clinical data and whole blood were collected. Patients were stratified based on disease activity. Remission was defined as no recorded DAS28-CRP≥2.4, no swollen joints, no C-reactive protein (CRP) of >5mg/L, and on a stable DMARD dose and no reported disease flare/loss of remission in the 6 months prior. Non-remission was defined as any other disease activity which does not fulfil the remission definition. Patients on abatacept, or methotrexate monotherapy and healthy volunteers were recruited as comparison groups. A separate cohort of anti-TNF patients (longitudinal cohort) who have been in remission on a stable dose of anti-TNF for ≥6 months and no use of corticosteroids in the last 6 months, was also recruited. Whole blood was obtained prior to dose tapering (dose halving) and at the point of a flare. Whole blood was processed by gradient centrifugation to obtain peripheral blood mononuclear cells (PBMC). PBMC were stained with fluorochrome-conjugated antibodies for multi-parameter flow cytometry. Analysis was performed on live lymphocytes using FlowJo software version 10.8. Two-tailed Mann-Whitney U test or unpaired t-test were used to obtain unadjusted values, analysis of variance (ANOVA) of log-transformed data was used to obtain age-adjusted values, Spearman’s rank correlation was used to compare correlation between Temra and CRP.ResultsRA patients (36 anti-TNF, 12 abatacept, 16 methotrexate monotherapy) and 14 healthy individuals were recruited. There was a higher proportion of CD4 (age-adjusted p = 0.004) and CD8 Temra (age-adjusted p = 0.0007) in RA patients on anti-TNF with persistent disease activity compared to those who had achieved remission. These differences were confirmed when analysing absolute numbers of CD4 and CD8 Temra. Unexpectedly, the difference in Temra frequency between remission and non-remission RA was not observed in patients treated with methotrexate or abatacept. The median CD4 and CD8 Temra frequencies in RA patients in remission with all treatments studied were similar to healthy individuals.Temra were not observed to increase with age in the anti-TNF, abatacept, or methotrexate cohorts in contrast to previous reports in healthy individuals2. The frequency of CD4 and CD8 Temra correlated with CRP only in patients on anti-TNF (CD4 Temra Spearman r = 0.5185, p = 0.001, and CD8 Temra Spearman r = 0.5040, p = 0.005).There was an increase in CD4 (p = 0.003) but not CD8 Temra at 3 months in patients who flared on tapering anti-TNF compared to those who remained in remission (Figure 1).ConclusionIncreased CD4 and CD8 Temra frequency were associated with persistent disease activity in anti-TNF treated patients but not with other DMARD therapies (abatacept and methotrexate). CD4 Temra increased in those who flared on tapering anti-TNF. These results suggest that Temra may play a role in driving persistent disease activity refractory to anti-TNF therapy rather than merely a marker of inflammation.