Scientific article
Open access

Synovial tissues concentrate secreted APRIL

Published inArthritis research & therapy, vol. 11, no. 5, R144
Publication date2009

INTRODUCTION: A proliferation-inducing ligand (APRIL) from the TNF family, owing to its role in the generation and survival of plasma cells (PCs), is currently targeted for rheumatoid arthritis (RA) treatment. However, little is known about APRIL expression in RA lesions, hampering our understanding of the way APRIL may modulate this autoimmune disease. METHODS: We performed immunological staining of human normal, non-RA and RA synovial tissues with a pair of antibodies specifically recognizing APRIL-producing cells and secreted APRIL. RESULTS: We detected significant amounts of secreted APRIL in normal synovium mostly concentrated around blood vessels and at the lining layer, but no cells producing APRIL. Meanwhile, we observed that blood neutrophils constitutively secrete APRIL, indicating that blood APRIL may diffuse into the synovium via its fenestrated vessels. Synovium from non-RA and RA patients retained similarly secreted APRIL, but in this case APRIL-producing cells, including neutrophils and macrophages, were present in the tissue. Notably, PCs--when present in RA synovium--accumulated in areas of APRIL retention, spreading from blood vessels towards the lining layer. CONCLUSIONS: PCs accumulate in synovial zones rich in secreted APRIL, consistent with a pro-survival role of APRIL for PCs in RA. The concentration of APRIL by normal synovium indicates that this tissue may constitute a proper environment for PCs even before RA onset.

  • Adult
  • Aged
  • Aged, 80 and over
  • Arthritis, Rheumatoid/*metabolism
  • Female
  • Flow Cytometry
  • Humans
  • Immunohistochemistry
  • Male
  • Middle Aged
  • Neutrophils/metabolism
  • Plasma Cells/*metabolism
  • Synovial Membrane/*secretion
  • Tumor Necrosis Factor Ligand Superfamily Member 13/*secretion
Citation (ISO format)
GABAY, Cem et al. Synovial tissues concentrate secreted APRIL. In: Arthritis research & therapy, 2009, vol. 11, n° 5, p. R144. doi: 10.1186/ar2817
Main files (1)
ISSN of the journal1478-6354

Technical informations

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