POS1207 AMELIORATION OF RHEUMATOID ARTHRITIS IN PREGNANCY IS NOT ASSOCIATED WITH ENHANCED FUNCTION OF REGULATORY T CELLS

• Published in: Annals of the rheumatic diseases Vol. 83; no. Suppl 1; p. 721
• Main Authors: Raine, C., Robinson, G., Ciurtin, C., Manson, J., Williams, D., Jury, E., Giles, I.
• Format: Journal Article
• Language: English
• Published: Kidlington BMJ Publishing Group Ltd and European League Against Rheumatism 01.06.2024; Elsevier B.V; Elsevier Limited
• Subjects: Adaptive immunity; Antibiotics; Apoptosis; Brefeldin A; CD20 antigen; CD25 antigen; CD28 antigen; CD3 antigen; CD4 antigen; CD69 antigen; Cell death; CTLA-4 protein; Cytokines and Chemokines; Flow cytometry; Foxp3 protein; Fusion protein; Hydroxychloroquine; Hypotheses; Immunological tolerance; Immunoregulation; Ionomycin; Leukocytes (mononuclear); Lymphocytes; Lymphocytes T; PD-1 protein; Pregnancy; Pregnancy and reproduction; Remission; Rheumatoid arthritis; Scientific Abstracts; Thymus; Transforming growth factor-b; γ-Interferon; Remission; Pregnancy and reproduction; Adaptive immunity; Cytokines and Chemokines
• ISSN: 0003-4967; 1468-2060
• DOI: 10.1136/annrheumdis-2024-eular.1007

Background:The ameliorative effect of pregnancy on rheumatoid arthritis (RA) was first reported in the 1930s but the cause remains unclear. CD4+CD25+FOXP3+ regulatory T cells (Tregs), which are defective in RA, have a crucial role in maintaining maternofoetal tolerance in pregnancy and their circulating number and function was previously found to correlate with amelioration of RA in the third trimester [1].Objectives:We conducted a prospective cohort study of pregnant women with RA (RA-P) to test the hypothesis that amelioration of RA in pregnancy is associated with enhanced Treg function, which is lost in postpartum (PP) flare.Methods:RA-P who fulfilled 2010 ACR/EULAR classification criteria were assessed at >28 weeks (T3) and within 6 months PP. RA disease activity was measured with Disease Activity Score (DAS)-28(3)CRP. Simplified definitions of disease activity response in pregnancy and PP were used based on [2]: DAS response in pregnancy was defined as: ΔDASpre-preg–T3 <-0.6 (ΔDASpre-preg–T3 calculated as: DAS28(3)CRP in T3 – DAS28(3)CRP pre-pregnancy (within 6 months, obtained from patient records)). PP flare was defined as ΔDAST3 – PP >0.6 (ΔDAST3 – PP calculated as: DAS28(3)CRP in PP – DAS28(3)CRP in T3).Peripheral blood was collected from subjects with isolation of peripheral blood mononuclear cells (PBMCs). Multiparameter flow cytometry was used for detailed immunophenotyping of Tregs and CD4+CD25- responder T cells (Tresps). Tregs were gated on CD4+CD25+CD127-FOXP3+. Functional markers included CD69, programmed cell death-protein 1 (PD-1) and Helios (marker of thymic Tregs). Intracellular cytokine staining (transforming growth factor (TGF)-β, interferon (IFN)-γ) was undertaken after overnight stimulation of PBMCs with anti-CD3, anti-CD28 and IL-2 followed by 4 hour stimulation with PMA, ionomycin and brefeldin A. Relative Treg:Tresp activity was assessed by the ratio of expression of these markers.Results:N=28 RA-P were recruited, mean age 34.2 years (27–42). Medication use comprised n=5 patients on no treatment; hydroxychloroquine, n=14; sulfasalazine, n=13; anti-tumour necrosis factor, n=6; anti-IL-6, anti-CD20 and CTLA-4 fusion protein n=1 each. N=4 patients on prednisolone >10 mg were excluded. Of remaining patients with available data, n=9 patients experienced DAS response in pregnancy (RA-P-R) and n=9 did not respond (RA-P-NR); n=6 patients experienced PP flare (RA-PP-F) and n=16 did not flare (RA-PP-NF), Table 1.Multiple unpaired t tests found an increase in %Tregs in T3 of RA-P-R compared to RA-P-NR. However, markers of Treg function were lower in RA-P-R compared to RA-P-NR: median fluorescence intensity (MFI) CD69, % and MFI of TGF-β+ as well as Tresp % IFN-γ (p < 0.05, Figure 1A). These functional markers as well as Treg TGF-β:Tresp IFN-γ production and Treg:Tresp CD69 expression were positively correlated with ΔDASpre-preg–T3 (Figure 1B). Receiver operating characteristic (ROC) analyses showed that these markers were excellent predictors of DAS response in RA-P (Figure 1C).PP flare was associated with reduced Treg but elevated total lymphocyte counts. Treg CD69 expression and Treg:Tresp CD69 expression were increased in PP flare (Figure 1D).T3 parameters were compared in RA-PP-F versus RA-PP-NF. Tresp IFN-γ production was significantly increased at T3 in RA-PP-F (Figure 1E). The proportion and MFI of Helios+ Tregs and Treg:Tresp % PD-1 were significantly reduced in RA-PP-F and predicted PP flare at T3 (Figure 1F).Conclusion:1.In contrast to previous findings and our hypothesis, amelioration of RA in pregnancy was associated with increased number but reduced function of Tregs, and with reduced function (IFN-γ production) by Tresps.2.Tregs were activated in PP flare as assessed by CD69 expression3.Treg/Tresp alterations in RA-PP-F were evident at T3, with increased Tresp production of IFN-γ, Treg induction (increased proportion of Helios- Tregs), and reduced Treg: Tresp PD-1 expression. These parameters could be studied as potential predictors of PP flare in future work.REFERENCES:[1] Forger F et al. Ann Rheum Dis. 2008;67(7):984-90.[2] de Man YA et al. Arthritis Rheum. 2008;59(9):1241-8.Acknowledgements:NIL.Disclosure of Interests:Charles Raine UCB, George Robinson: None declared, Coziana Ciurtin: None declared, Jessica Manson: None declared, David Williams: None declared, Elizabeth Jury: None declared, Ian Giles: None declared