Article Text

PDF
FRI0361 Interleukin-4 induces class-switching to IGG4 and synergistically contributes to plasmablasts differentiation with interleukin-21 through CD40 dependent manner in IGG4-related disease
  1. M Akiyama,
  2. H Yasuoka,
  3. K Yoshimoto,
  4. T Takeuchi
  1. Division of Rheumatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan

Abstract

Background IgG4-related disease (IgG4-RD) is a lymphoproliferative disorder characterized by elevated serum levels of IgG4 and increased numbers of circulating plasmablast. We have previously reported that class-switching to IgG4 and plasmablast differentiation are mediated by follicular helper type 2 T cells which are known to secrete interleukin (IL)-4, IL-13, IL-10 and IL-21 (1, 2). However, the cytokines which play a role in the IgG4 class-switching and plasmablast differentiation through cell to cell contact remain unclear in IgG4-RD.

Objectives The aim of this study was to elucidate the role of follicular helper type 2 T cell cytokines (IL-4, IL-13, IL-10, and IL-21) and cell to cell interaction in the pathogenesis of IgG4-RD.

Methods Peripheral blood mononuclear cells (PBMCs) were prepared from seven consecutive patients with active, untreated, newly diagnosed IgG4-RD and five healthy controls. To identify the cytokines which induce IgG4 class-switching, the cells were stimulated with IL-4, IL-13 or the combination with other cytokines, such as IL-10 or IL-21. The amounts of IgG4 and IgG in the culture supernatants were measured by cytometric bead arrays. The expression level of activation-induced cytidine deaminase (AID; an enzyme essential for class-switch recombination) was analyzed by quantitative PCR to confirm the induction of class-switching by stimulation with cytokines. The numbers of plasmablasts and plasma cells induced by cytokines stimulation were examined by flow cytometry. Moreover, an anti-CD40 antibody was added to the culture to elucidate the effects of cell to cell interaction on the differentiation of plasmablasts or plasma cells.

Results IL-4 significantly induced CD40-stimulated PBMCs to undergo IgG4 class-switching in patients with IgG4-RD, while IL-13 did not show any positive effects. Moreover, the IgG4/IgG ratio in culture supernatants was also significantly higher in the stimulation with IL-4 compared to other cytokines in IgG4-RD. In addition, the expression levels of AID mRNA were increased by stimulation with IL-4 compared to that by no stimulation or CD40 stimulation in IgG4-RD. On the other hand, PBMCs from healthy controls showed no significant difference in IgG4 production after stimulation with either IL-4 or IL-13. Furthermore, IgG4 production stimulated with IL-4 was significantly higher in IgG4-RD than that in healthy controls. Assessing additional effects of IL-10 or IL-21 on IL-4, IL-10 and IL-21 did not increase IgG4 production and IgG4/IgG ratio compared to IL-4 alone in IgG4-RD. However, importantly, IL-21 synergistically induced plasmablasts or plasma cells differentiation in combination with IL-4, whereas no obvious change was observed in PBMCs stimulated with IL-4 alone in IgG4-RD. Of note, the differentiation of plasmablasts and plasma cells by IL-4 and IL-21 was markedly abolished in the absence of CD40 stimulation.

Conclusions Our results strongly suggest that IL-4 plays a pivotal role in IgG4 class-switching, and the effective collaboration between IL-4 and IL-21 contributes to plasmablasts and plasma cells differentiation via CD40 dependent manner in patients with IgG4-RD.

References

  1. Akiyama M, et al. Arthritis Res Ther. 2016;18:167.

  2. Akiyama M, et al. Arthritis Rheumatol. 2015;67:2476–81.

References

Acknowledgements We thank all the physicians and others caring for the patients enrolled in our study.

Disclosure of Interest None declared

Statistics from Altmetric.com

Request permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.