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07-04-2017 | Rheumatology | News | Article

Immune cell analysis could predict biological DMARD response in RA patients

medwireNews: Different biological disease-modifying antirheumatic drugs (DMARDs) induce distinct changes in immune cell subsets among patients with rheumatoid arthritis (RA), study results suggest.

“Immunophenotypic analysis might be useful in evaluating the immune signatures and in predicting the therapeutic efficacy for individual patients,” say Yoshiya Tanaka (University of Occupational & Environmental Health, Kitakyushu, Japan) and study co-authors.

The team analyzed peripheral blood immune cell counts using flow cytometry, and found that proportions of T follicular helper (Tfh) cells, IgD CD27 double negative B cells, and plasmacytoid dendritic cells (pDCs) were higher in blood samples taken from 108 patients with RA compared with 33 healthy controls.

For participants undergoing treatment with tumor necrosis factor (TNF) inhibitors (including infliximab, etanercept, and adalimumab), the proportion of naïve T cells and pDCs in peripheral blood significantly decreased from baseline to week 24, but the proportion of effector memory T cells, T helper 17 cells, Tfh cells, and immunoglobulin M memory B cells significantly increased.

On the other hand, treatment with the interleukin-6 inhibitor tocilizumab reduced the number of double-negative B cells but increased that of myeloid DCs, whereas there was a “marked decrease” in the proportion of Tfh cells among patients undergoing abatacept treatment, say the researchers.

These heterogeneous changes in immune cell subsets “may indicate the diversity of immunopathogenic [processes] in RA,” they explain in Rheumatology.

In an analysis of baseline prognostic factors, Tanaka and colleagues found that the proportion of Tfh cells before the start of treatment significantly predicted a reduction in disease activity in response to abatacept treatment – as measured by the disease activity score 28 based on the erythrocyte sedimentation rate (DAS28-ESR) – at week 24, with a correlation coefficient of –0.34. By contrast, the proportion of naïve cytotoxic T cells at baseline was a significant predictor of poor response to abatacept therapy (correlation coefficient=0.36).

The proportion of plasmacytoid dendritic cells at baseline was a significant predictor of response to TNF inhibitor therapy (correlation coefficient=–0.34), but the team was not able to identify markers of response to tocilizumab treatment.

Although the study results suggest that “Tfh cells seem a potential target for abatacept,” the authors caution that as their study was observational, “the properties of each drug cannot simply be compared.” They also note that immune cell counts were taken from peripheral blood only and not from inflamed synovia.

“In future, in-depth study coupled with evaluation of the exact number of the cells in peripheral blood and in synovial tissues may be more useful,” they suggest.

By Claire Barnard

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