Session Type: Abstract Submissions (ACR)
Tofacitinib is the first approved Janus Kinase (JAK) Inhibitor for the treatment of rheumatoid arthritis (RA). The JAK/STAT pathway-inhibition leads to dysfunction of several processes of the acquired and innate immunity as well as haematopoesis. Beyond this, JAK3, which is exclusively expressed on haematopoetic cells, is known to be involved in the maturation and activation of dendritic cells (DCs), but its specific role remains controversial. Since DCs play a key role in the pathogenesis of RA, we investigated the in vivo effect of Tofacitinib on DC maturation and allogeneic T cell activation.
Monocytes were collected from healthy donors and cultured for 5 days in the presence of GM-CSF and IL-4 to generate immature dendritic cells (iDCs). To induce maturation, iDCs were cultured for 2 days in the presence of LPS (10 ng/ml) or a cocktail consisting of IL-1β (10 ng/ml), TNF-α (10 ng/ml), IL-6 (1000 U/ml) and Prostaglandin E2 (1mg/ml) or LPS with or without different concentrations of tofacitinib (10-300 nM). After seven days of culture, mature DCs (mDCs) were harvested and phenotypically characterized using FACS analysis. To evaluate mDC function, mixed leukocyte reactions (MLR) were established by incubation of 5×104 allogeneic T cells with different amounts of mDCs at stimulator:responder (S:R) ratios from 1:625 to 1:1 in the presence of different concentrations of tofacitinib, or abatacept. On day 5 of co-culture, 1 µCi of 3H-methyl-thymidine/well was added and T cell proliferation was determined after 24h using a liquid scintillation counter.
There was no relevant inhibition of DC maturation in the presence of tofacitinib as FACS analysis revealed similar expression patterns for HLA-DR and CD83 in all cultures (HLA-DR+: 55.4%, 45.5%, 62.5%; CD83+: 82%, 74%, 80,3% for tofacitinib concentrations from 10nM, 30nM and 100nM, respectively). Furthermore, expression of co-stimulatory molecules CD80 and CD86 (>92% CD80+ and CD86+ for all tofacitinib concentrations) was not affected by tofacitinib. In addition, proliferation of allogeneic T cells in co-cultures with mDCs was not significantly impaired as similar proliferation rates could be observed at all S:R ratios despite the presence of tofacitinib (mean increase of 27% cpm for all S:R ratios vs untreated mDC after LPS stimulation, mean decrease of 6% cpm for all S:R ratios after stimulation with cytokine cocktail vs. untreated mDC). In contrast, there was a concentration dependent inhibition up to 75% of T cell proliferation in co-cultures treated with abatacept.
Conclusion: The present results demonstrate that DC maturation as well as proliferation of allogeneic T cells in MLR’s is not significantly affected by tofacitinib. Therefore, modulation of the JAK pathway in other cell populations might be responsible for the anti-inflammatory effects observed upon tofacitinib treatment in vivo.
E. Le Bras,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/tofacitinib-does-not-inhibit-dendritic-cell-maturation-and-t-cell-proliferation-in-vitro/