Pos1203 Psoriatic Arthritis, Seronegative Rheumatoid Arthritis, and Seropositive Rheumatoid Arthritis: Circulating Immune Cell and Cytokine Phenotypic Profiles

Background: Immunological dysregulation constitutes the primary pathogenic mechanism in Psoriatic Arthritis (PsA) and Rheumatoid Arthritis (RA). However, these conditions exhibit distinct differences at the histopathological and clinical levels. A specific subset within RA, known as Seronegative Rheumatoid Arthritis (SnRA), shares similarities with PsA, posing challenges for clinical differentiation. Objectives: This study aims to investigate the peripheral blood lymphocyte subsets, CD4+ T cell distribution characteristics, and differential expression of cytokines in patients with PsA, SnRA, and SpRA. Methods: A total of 78 patients with PsA, 41 patients with SnRA, and 79 patients with SpRA who sought medical attention at the Rheumatology and Immunology Department of Shanxi Medical University Second Hospital from January 2020 to October 2020 were included in this study. General clinical data were collected, and peripheral blood lymphocyte subsets (T cells, B cells, CD4+ T cells, CD8+ T cells, NK cells), CD4+ T cell subsets (Th1 cells, Th2 cells, Th17 cells, Treg cells), and serum levels of cytokines (IL-2, IL-4, IL-6, IL-10, INF-γ, TNF-α) were measured using flow cytometry and CBA, respectively. Results: (1) PsA exhibited varying degrees of elevation in peripheral blood T cell count, B cell count, CD4+ T cell count, CD8+ T cell count, and Th2 cell count compared to SnRA and SpRA (Figure 1A); (2) SpRA patients showed significantly higher levels of various cytokines (IL-2, IL-4, IL-6, IL-10, IL-17, INF-γ, TNF-α) compared to both SnRA and PsA, with no significant differences observed between PsA and SnRA in cytokine levels (Figure 1B); (3) SpRA patients exhibited elevated Th1/Th2 and Th17/Treg ratios compared to the other two groups (Figure 2A); (4) Principal Component Analysis (PCA) of lymphocyte subset ratios (CD4+ T/CD8+ T, Th1/Th2, Th17/Treg) and cytokine levels (IL-2, IL-4, IL-6, IL-10, IL-17, INF-γ, TNF-α) revealed strikingly similar overall distribution characteristics in lymphocyte subset ratios and cytokine levels between PsA and SnRA patients (Figure 2B). Conclusion: In comparison to PsA and SnRA, patients with SpRA exhibit more severe immunological dysregulation and higher levels of inflammatory cytokines. Additionally, the overall distribution characteristics of lymphocyte subset ratios and cytokine levels are similar between PsA and SnRA patients, providing immunological evidence for the clinical and pathological similarities between these two diseases. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.