Background/Purpose: Past studies have shown a critical link between alteration in human commensal microbiota and development of Rheumatoid Arthritis (RA), however how CD4⁺ T-cell responses to commensal microbes promote autoimmune processes in RA patients remain undefined. Here we carry out in-depth characterization of commensal reactive T-cells to elucidate their potential role in RA pathogenesis.

Methods: We designed a high throughput 27-flouorochrome spectral panel comprising of diverse trafficking and chemokine markers to study the phenotypic diversity and differentiation state of commensal reactive-T cells. We selected a set of gut and oral bacteria (P. copri, C. aerofacians, L. salivarius, P. gingivalis) previously reported to be increased in RA patients for T cell stimulation. Bacterial lysates were prepared by sonication-based method and incubated with PBMCs from patients meeting the 2010 ACR criteria for RA and age-matched controls. Commensal-specific T cells were identified by the expression of activation markers and analyzed on spectral flow AURORA.

Results: Our preliminary results showed that commensal lysate responding CD4+ T cells from RA patients displayed elevated levels of T follicular helper cells (Tfh) associated markers (CXCR5 and PD-1) and migration marker (CD49D and Integrin b1) compared to healthy controls across all stimulation conditions. For some microbial lysates, we additionally observed increased levels of trafficking receptors, CCR2, CCR6, CLA, and CCR10, on commensal bacteria reactive CD4+ T cells from RA patients compared to healthy controls.

Conclusion: Our data suggest that immune homeostasis with the microbial environment is altered in RA patients. Engagement with commensal bacteria may activate CD4+ T cells and polarize them into Tfh cells with increased migratory potential. Future studies will focus on understanding how these cells promote inflammation and autoimmunity in RA patients.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/commensal-reactive-t-cells-display-diverse-phenotype-in-rheumatoid-arthritis-patients/