POS0014 SINGLE-CELL PERIPHERAL BLOOD ANALYSIS IDENTIFIES KEY IMMUNE SIGNATURES ASSOCIATED WITH REFRACTORY RHEUMATOID ARTHRITIS

Background

Refractory rheumatoid arthritis (refRA) persists in the targeted therapy era with up to 20% of patients failing multiple classes of biologic (b) and/or targeted synthetic (ts) DMARDs.^[1,2] Currently, there is limited understanding of the immune composition of refRA.

Objectives

To characterise the peripheral immune landscape of patients with refRA as compared to early RA.

Methods

In the Leeds observational cohort study, peripheral blood mononuclear cells were collected from 30 treatment naïve early rheumatoid arthritis (ERA) and 23 refractory rheumatoid arthritis (refRA) patients. ERA patients have <12 months symptoms duration and refRA patients had active (at least moderate disease) RA despite ≥2 classes of b and/or ts DMARDs. Using a panel of 36 antibodies, we conducted mass cytometry by time of flight (CyTOF) analysis to identify alterations in peripheral immune cell subsets and functional markers between ERA and refRA, using unsupervised clustering and linear mixed-effects models, which adjusted for age, sex, seropositivity and batch. A false discovery rate of 0.05 was applied. All analyses were performed using R v4.0.2.

Results

The cohort had a higher proportion of females (73.3% ERA and 87% refRA) and a median age of 61 years. The majority were seropositive (86.7% ERA, 91.3% reRA). Among the refRA patients, median number of failed b/tsDMARDs was 3 (range 2-7). Overall, we identified 17 phenotypically distinct subsets from the immune cell population. ERA and refRA had similar abundance of immune cell sub-populations. However, functional marker differences in these cell subpopulations were observed between refRA and ERA: higher TNFR expression (monocytes, dendritic and FCεRI+ cells), CD80 (FCεRI+ cells), CD28 (neutrophils), granzyme B (CD4+ naïve T cells), and lower CTLA4 (monocytes), CD127 (NK cells), CD38 (basophils), NKP46 (CD8+ naïve T cells) and PD1 (CD4+ naïve T cells).

Conclusion

We report alteration in the functional profile across multiple immune cell types between refRA and ERA. These findings provide new insights into immunological traits of refRA and potential targets for therapy.

References

[1]Nagy, G. et al (2021). EULAR definition of difficult-to-treat rheumatoid arthritis. Annals of the Rheumatic Diseases, 80(1), 31. [2]Roodenrijs, N. M. T. et al. (2018). Characteristics of difficult-to-treat rheumatoid arthritis: results of an international survey. Annals of the Rheumatic Diseases, 77(12), 1705.

Functional makers differences (refRA vs ERA)

Table 1 shows functional markers expression across immune cell clusters in refRA compared to ERA, using linear mixed modelling (FDR <0.05).

Acknowledgements

This study was supported by a UCB pharma PhD studentship (TB).

Disclosure of Interests

None Declared.