Artikel
Fibroblast like synoviocytes (FLS) are capable of inducing class switch recombination (CSR) in naive B cells from healthy donors; the process appears to be IL-6 and CD40L dependent
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Autoren
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Dennis Bleck
- Universitätsklinikum Düsseldorf, Poliklinik, Funktionsbereich & Hiller Forschungszentrum für Rheumatologie, Düsseldorf
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Georg Pongratz
- Universitätsklinikum Düsseldorf, Poliklinik, Funktionsbereich & Hiller Forschungszentrum für Rheumatologie, Düsseldorf
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Matthias Schneider
- Poliklinik, Funktionsbereich & Hiller Forschungszentrum für Rheumatologie, UKD, Heinrich-Heine-Universität Düsseldorf, Düsseldorf
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Torsten Lowin
- Poliklinik, Funktionsbereich & Hiller Forschungszentrum für Rheumatologie, UKD, Heinrich-Heine-Universität Düsseldorf, Düsseldorf
| Veröffentlicht: | 8. Oktober 2019 |
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Gliederung
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Background: Rheumatoid Arthritis (RA) is a disease characterized by chronic inflammation of the synovial tissue in joints. It is driven by highly activated B cells. Synovial cells, primarily Fibroblast like synoviocytes (FLS) play an important role in activating these B cells. It was previously shown, that FLS upregulate CD40L and IL-6 under pro-inflammatory conditions (unpublished data). In order to investigate the interactions responsible for B cell activation, a co-culture model was established with RAFLS and SF from Osteoarthritis (OA) patients.
Methods: IgD+ B cells were isolated from human peripheral blood by MACS and co-cultured w/wo SFs in medium only, in the presence of of various cytokines, TLR agonists and with or without CD40L neutralizing antibodies or Tocilizumab. B cell subpopulations, survival and proliferation were determined by FACS. IgG and IgM were measured by ELISA.
Results: Without additional stimulation IgD+ B cells are reduced in FLS co-culture after 6 days (RAFLS: -26.2 % +/- 12.8 %; p = 0.06; OAFLS: -23.1 +/- 5.5 %; p = 0.003 compared to B cell control). With IFN-gamma, the reduction of IgD+ B cells is even more pronounced (RAFLS: -44.6 % +/- 4.7 %; p = 0.0003; OAFLS: -33.6 % +/- 9.2 %; p = 0.003 compared to B cell control). The proportion of CD138+ B cells is increased after 6 days in co-culture with IFN - gamma (RAFLS: from 0.37 % to 16 % +/- 1.8 %; p = 0.0009; OAFLS: from 0.37 % to 17.5 % +/- 2.4 %; p = 0.0005). IgM could only be measured in considerable amounts in the supernatant after stimulation with CpG and exclusively in the co-cultures (RAFLS: from: 6.7 ng/mL +/- 0.95 ng/mL to 517.5 ng/mL +/- 228.4 ng/mL; p = 0.002; OAFLS: from: 5.9 ng/mL +/- 0.3 ng/mL to 189.6 ng/ml +/-204.4 ng/ml; p = 0.009 compared to B cell control). IgM was reduced when IL-6 (RAFLS: from 14.9 ng/mL +/- 0.8 ng/mL to 10.6 ng/mL +/- 0.4 ng/mL p = 0.03; OAFLS: from 17.3 ng/mL +/- 0.7 ng/mL to 12.4 ng/mL +/- 0.7 ng/mL; p = 0.02) or CD40L (RAFLS: from 110.5 ng/mL +/- 15.5 ng/mL to 49.2 ng/mL +/- 5.2 ng/mL, p = 0.04; OAFLS: 155.7 ng/mL +/- 5.8 ng/mL to 54.2 ng/mL +/- 5.0 ng/mL, p < 0.01) were blocked. IgG was reduced when CD40L was blocked in (RAFLS: from 18.2 ng/mL +/- 1.0 ng/mL to 16.0 ng/mL +/- 0.9 ng/mL, ns; OAFLS: from 20.7 ng/mL +/- 1.2 ng/mL to 15.6 ng/mL +/- 0.7 ng/mL, p = 0.05).
Conclusion: FLS are capable of inducing CSR in naïve B cells, probably through CD40L and IL-6 upregulated under pro-inflammatory conditions.
