Effect of Clonally Expanded PD‐1^highCXCR5–CD4+ Peripheral T Helper Cells on B Cell Differentiation in the Joints of Patients With Antinuclear Antibody–Positive Juvenile Idiopathic Arthritis

Abstract

Objective. Antinuclear antibody (ANA)-positive juvenile idiopathic arthritis (JIA) is characterized by synovial B cell hyperactivity, but the precise role of CD4+ T cells in promoting local B cell activation is unknown. This study was undertaken to determine the phenotype and function of synovial CD4+ T cells that promote aberrant B cell activation in JIA.Methods. Flow cytometry was performed to compare the phenotype and cytokine patterns of PD-1 high CD4+ T cells in the synovial fluid (SF) of patients with JIA and T follicular helper cells in the tonsils of control individuals. TCRVB next-generation sequencing was used to analyze T cell subsets for signs of clonal expansion. The functional impact of these T cell subsets on B cells was examined in cocultures in vitro.Results. Multidimensional flow cytometry revealed the expansion of interleukin-21 (IL-21) and interferon-γ (IFNγ)coexpressing PD-1 high CXCR5-HLA-DR+CD4+ T cells that accumulate in the joints of ANA-positive JIA patients. These T cells exhibited signs of clonal expansion with restricted T cell receptor clonotypes. The phenotype resembled peripheral T helper (Tph) cells with an extrafollicular chemokine receptor pattern and high T-bet and B lymphocyteinduced maturation protein 1 expression, but low B cell lymphoma 6 expression. SF Tph cells, by provision of IL-21 and IFNy, skewed B cell differentiation toward a CD21 low/-CD11c+ phenotype in vitro. Additionally, SF Tph cell frequencies correlated with the appearance of SF CD21 low/-CD11c+CD27-IgM-double-negative (DN) B cells in situ.Conclusion. Clonally expanded CD4+ Tph cells accumulate in the joints of ANA-positive JIA patients and, in particular, promote CD21 low/-CD11c+ DN B cell differentiation. The expansion of Tph cells and DN B cells might reflect the autoimmune response in the joints of ANA-positive JIA patients.

Molecular mechanisms controlling age‐associated B cells in autoimmunity*

“…[81][82][83] The T cell source of IL-21 and IFNγ may vary depending on the setting with T FH cells, especially CXCR3 + expressing T FH 1 cells, CXCR5 -PD1 hi T peripheral helper cells (Tph), and T H 1 cells having all been shown to regulate ABC expansion and differentiation to varying extents. 27,80,84,[86][87][88] The close interdependence between the expansion of ABCs and the increased accumulation of T FH cells observed in lupus models, 61,64 furthermore, suggests that ABCs and progeny like the CD11c + pre-GC B cells by acting as APCs can augment the expansion of their own T cell helpers and further fuel autoimmunity.…”

“…The cross‐talk between these two cytokines has not been fully delineated but may function at multiple levels and affect both differentiation of ABCs into ASCs via IFNγ‐mediated upregulation of the IL‐21R 85 and potentially more complex effects on the ability of ABCs to undertake a GC differentiation route 81‐83 . The T cell source of IL‐21 and IFNγ may vary depending on the setting with T FH cells, especially CXCR3 + expressing T FH 1 cells, CXCR5 ‐ PD1 hi T peripheral helper cells (Tph), and T H 1 cells having all been shown to regulate ABC expansion and differentiation to varying extents 27,80,84,86‐88 . The close interdependence between the expansion of ABCs and the increased accumulation of T FH cells observed in lupus models, 61,64 furthermore, suggests that ABCs and progeny like the CD11c + pre‐GC B cells by acting as APCs can augment the expansion of their own T cell helpers and further fuel autoimmunity.…”

B Cells on the Stage of Inflammation in Juvenile Idiopathic Arthritis: Leading or Supporting Actors in Disease Pathogenesis?

“…A distinctive feature of chronic inflammatory arthritis is the presence of synovial lymphocytic infiltrates that play a role in disease pathogenesis by secretion of pro-inflammatory cytokines and other soluble mediators ( 156 – 166 ). Indeed, both B and T cells are detected in synovial infiltrates from JIA and RA patients ( 17 , 18 , 69 , 79 , 156 , 163 – 165 , 167 – 172 ). In particular, high levels of plasma cells infiltration have been detected in the synovial membrane of JIA patients ( 69 , 173 ).…”

T cell help in the autoreactive germinal center

“…Peripheral helper T cells were identified in the synovium of seropositive RA patients and are distinct from cTFH cells due to their PD‐1 hi CXCR5 − Bcl6 − profile and ability to migrate to peripheral sites of inflammation 107,300–303 . TPH cells produce IL‐21 and CXCL13, 304 express TFH signature genes, 289 exhibit hallmarks of exhaustion, 289 can stimulate PB formation in vitro , 289,304,305 and correlate with age‐associated CD11c + CD21 − B cell (ABC) levels 304,306 . Antigen‐specific TPH cells have been identified in celiac disease and autoimmune hepatitis, 307,308 suggesting that TCR specificity influences TPH fate and possibly function.…”

“…107,[300][301][302][303] TPH cells produce IL-21 and CXCL13, 304 express TFH signature genes, 289 exhibit hallmarks of exhaustion, 289 can stimulate PB formation in vitro, 289,304,305 and correlate with age-associated CD11c + CD21 − B cell (ABC) levels. 304,306 Antigen-specific TPH cells have been identified in celiac disease and autoimmune hepatitis, 307,308 suggesting that TCR specificity influences TPH fate and possibly function. Other CD4 T cell populations such as resident helper T (TRH) cells, 309,310 CXCR3 + PD1 hi CD4 T cells, 301 or TH17 cells 147,311 might also provide tissue-specific help to autoreactive B cells in autoimmune F I G U R E 3 Bystander activation and cross-reactivity of the TFH repertoire.…”