@article{FischerDirksKlaussneretal.2022,
  author    = {Fischer, Jonas and Dirks, Johannes and Klaussner, Julia and Haase, Gabriele and Holl-Wieden, Annette and Hofmann, Christine and Hackenberg, Stephan and Girschick, Hermann and Morbach, Henner},
  title     = {Effect of clonally expanded PD-1\(^h\)\(^i\)\(^g\)\(^h\) CXCR5-CD4+ peripheral T Helper cells on B cell differentiation in the joints of patients with antinuclear antibody-positive juvenile idiopathic arthritis},
  series = {Arthritis \& Rheumatology},
  volume    = {74},
  journal   = {Arthritis \& Rheumatology},
  number    = {1},
  doi       = {10.1002/art.41913},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256607},
  pages     = {150-162},
  year      = {2022},
  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\(^h\)\(^i\)\(^g\)\(^h\)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\(^h\)\(^i\)\(^g\)\(^h\)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 lymphocyte-induced 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\(^l\)\(^o\)\(^w\)\(^/\)\(^-\)CD11c+ phenotype in vitro. Additionally, SF Tph cell frequencies correlated with the appearance of SF CD21\(^l\)\(^o\)\(^w\)\(^/\)\(^-\)CD11c+CD27-IgM- double-negative (DN) B cells in situ.},
  language  = {en}
}
@article{DirksFischerHaaseetal.2021,
  author    = {Dirks, Johannes and Fischer, Jonas and Haase, Gabriele and Holl-Wieden, Annette and Hofmann, Christine and Girschick, Hermann and Morbach, Henner},
  title     = {CD21\(^{lo/-}\)CD27\(^-\)IgM\(^-\) Double-Negative B Cells Accumulate in the Joints of Patients With Antinuclear Antibody-Positive Juvenile Idiopathic Arthritis},
  series = {Frontiers in Pediatrics},
  volume    = {9},
  journal   = {Frontiers in Pediatrics},
  issn      = {2296-2360},
  doi       = {10.3389/fped.2021.635815},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236286},
  year      = {2021},
  abstract  = {Juvenile idiopathic arthritis (JIA) encompasses a heterogeneous group of diseases. The appearance of antinuclear antibodies (ANAs) in almost half of the patients suggests B cell dysregulation as a distinct pathomechanism in these patients. Additionally, ANAs were considered potential biomarkers encompassing a clinically homogenous subgroup of JIA patients. However, in ANA+ JIA patients, the site of dysregulated B cell activation as well as the B cell subsets involved in this process is still unknown. Hence, in this cross-sectional study, we aimed in an explorative approach at characterizing potential divergences in B cell differentiation in ANA+ JIA patients by assessing the distribution of peripheral blood (PB) and synovial fluid (SF) B cell subpopulations using flow cytometry. The frequency of transitional as well as switched-memory B cells was higher in PB of JIA patients than in healthy controls. There were no differences in the distribution of B cell subsets between ANA- and ANA+ patients in PB. However, the composition of SF B cells was different between ANA- and ANA+ patients with increased frequencies of CD21\(^{lo/-}\)CD27\(^-\)IgM\(^-\) "double negative" (DN) B cells in the latter. DN B cells might be a characteristic subset expanding in the joints of ANA+ JIA patients and are potentially involved in the antinuclear immune response in these patients. The results of our explorative study might foster further research dissecting the pathogenesis of ANA+ JIA patients.},
  language  = {en}
}