E069 Antagonism of IL-27 bioactivity

Abstract

Abstract Background/Aims Rheumatoid arthritis (RA) is a chronic autoimmune disease that results in joint damage and bony destruction. The inflammatory process is central in the pathology of RA, with cytokines mediating the inflammatory response. Cytokines, in particular IL-6, have been targeted as treatments for RA. The IL-27 cytokine is part of the IL-6 family, and acts via the same signalling pathway. IL-27 can have the same function as IL-6, but can also antagonise IL-6. The presence of ectopic lymphoid structures (ELSs) is associated with more severe disease and worse joint damage, and is also associated with low IL-27 levels. Hence, targeting IL-27 may aid in severe RA and offer a novel treatment option. Aims: 1) To generate a recombinant IL-27 antagonist, 2) to determine the concentration and bioactivity of IL-27 antagonist, 3) to test the bioactivity of IL-27 antagonist as an inhibitor of IL-27 activity. Methods Chinese hamster ovarian (CHO) cells were transduced with adenovirus to express the IL-27 antagonist. The concentration of these IL-27 antagonists was determined using ELISA. To determine the bioactivity of the IL-27 antagonist, both acute leukaemia cell lines (THP1 cells) and cells from C57BL/6J mice were treated with human IL-27 and IL-27 antagonists and STAT3 activation determined using flow cytometry and ELISA. Results THP1 cells treated with both 5ng/ml and 15ng/ml of human recombinant IL-27 showed STAT3 activation, with 29.4% and 30.7% of cells being STAT3 positive respectively. Cells that remained untreated only showed STAT3 activation in 2.54% of cells, indicating IL-27 has a role in the activation of the STAT3 pathway. STAT3 activation was not witnessed in CD4 cells from C57BL/6J mice treated with human recombinant IL-27. Furthermore, the recombinant IL-27 antagonist was not seen to be able to antagonise the actions IL-27 and alter STAT3 activation. Conclusion In conclusion, this study has demonstrated that IL-27 treatment of cells can cause increased STAT3 activation, however we were unable to demonstrate that the IL-27 antagonist was able to inhibit the actions of IL-27. IL-27 shows great potential for use as a novel therapy, since both its pro and anti-inflammatory functions can be targeted, however there needs to be much more information about the action of IL-27 as this is still largely unknown. Future studies could aim to optimise the protocol in order to understand the bioactivity of the IL-27 antagonist, thus understanding its role in altering STAT3 activation. Disclosure L. Green: None.