Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: Programmed death-1 (PD-1) is a central marker of T cell exhaustion. Exhausted T cells are present in inflammatory conditions, where they fail to eliminate the disease, and contribute to development of chronicity. They are suggested associated with a favorable prognosis in rheumatoid arthritis (RA), yet this is not fully elucidated 1. Extracellular vesicles (EVs) carrying proteins and microRNAs (miRNAs), among other constituents have been recognized as an important route of communication in the microenvironment.
Methods: Plasma and synovial fluid from RA patients were examined for the presence of EVs by capturing EVs on CD63 coated beads. EVs were furthermore isolated from supernatants from synovial fluid mononuclear cell (SFMC) and peripheral blood mononuclear cell (PBMC) cultures and characterized. The presence of PD-1 in EVs was examined by immuno-gold electron microscopy (EM), ELISA and western blotting. EVs purified from RA and healthy control (HC) PBMC cultures were co-cultured with lymphocytes and U937 cells (a cell line negative for PD-1), and EVs from WT mice were co-cultured with cells from PD-1-/- mice. PD-1 expression and cell proliferation of the exposed cells were analyzed. Finally, miRNA expression in EVs from cultured RA and HC cells was investigated by sequencing.
Results: PD-1 was detected in EVs in plasma and synovial fluid from RA patients. The presence of PD-1+ EVs in RA and HC cell culture supernatants was confirmed with immuno-gold EM and western blotting. Co-culturing these EVs with other cells induced PD-1 on the surface of lymphocytes and U937 cells. PD-1 was furthermore induced on PD-1-/- cells, when these were co-cultured with EVs from WT mice. EVs from RA PBMCs increased recipient cell proliferation, compared with both EVs from HC PBMCs and cells without EVs. This was not changed by addition of recombinant PD-L1. MicroRNAs repressing expression of the co-inhibitory receptors PD-1, TIM-3 and CTLA-4, all associated with an exhausted T cell profile, were up-regulated in EVs from stimulated PBMC cultures, however not in EVs from RA SFMCs. In EVs from non-stimulated RA PBMC cultures, miRNAs repressing the exhausted T cell pathway were down-regulated compared to EVs from HC cultures, suggesting that RA PBMCs in a steady-state aim to transfer information maintaining an exhausted T cell profile.
Conclusion: EVs from RA PBMCs carry and transfer PD-1 and incorporate less miRNAs repressing the PD-1 pathway and other markers of T cell exhaustion. Despite this, EVs from RA PBMCs increase proliferation of recipient cells in vitro. In addition, EVs from RA synovial cells express low levels of miRNA that regulate PD-1, TIM-3 and CTLA-4, facilitating continuous T-cell exhaustion. In conclusion this suggests that EVs are pro-inflammatory in RA, and contribute substantially to the development of chronicity. 1. McKinney, E. F., et al. Nature 523, 612–616 (2015).
To cite this abstract in AMA style:Greisen S, Yan Y, Hansen A, Venø M, Nyengaard JR, Hvid M, Sharpe A, Kjems J, Deleuran B. Rheumatoid Arthritis Cells Produce Extracellular Vesicles That Incorporate PD-1 and microRNAs Targeting the PD-1 Pathway in Surrounding Cells [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/rheumatoid-arthritis-cells-produce-extracellular-vesicles-that-incorporate-pd-1-and-micrornas-targeting-the-pd-1-pathway-in-surrounding-cells/. Accessed November 29, 2020.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/rheumatoid-arthritis-cells-produce-extracellular-vesicles-that-incorporate-pd-1-and-micrornas-targeting-the-pd-1-pathway-in-surrounding-cells/