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Endogenous Galectin-9 Suppresses Apoptosis in Human Rheumatoid Arthritis Synovial Fibroblasts


Pearson, Mark J; Bik, Magdalena A; Ospelt, Caroline; Naylor, Amy J; Wehmeyer, Corinna; Jones, Simon W; Buckley, Christopher D; Gay, Steffen; Filer, Andrew; Lord, Janet M (2018). Endogenous Galectin-9 Suppresses Apoptosis in Human Rheumatoid Arthritis Synovial Fibroblasts. Scientific Reports, 8(1):12887.

Abstract

Galectin-9 (Gal9) has been postulated to have anti-inflammatory properties based on the ability of exogenous Gal9 to induce apoptosis in synovial fibroblasts in animal models of rheumatoid arthritis (RA). Here we aimed to assess the potential role of endogenous Galectins, including Gal9, in the inflammatory pathology of the RA synovium in humans. Firstly expression of Galectins 1-9 was determined in synovial fibroblasts (RASF) and dermal fibroblasts (DF) isolated from RA patients, the latter representing a non-inflamed site. We then further challenged the cells with pro-inflammatory TLR agonists and cytokines and assessed Galectin expression. Gal9 was found to be differentially and abundantly expressed in RASF compared to DF. Agonists of TLR3 and TLR4, along with IFNgamma were also found to induce Gal9 expression in RASF. siRNA was then used to knock-down Gal9 expression in RASF and the effects of this on apoptosis and cell viability were assessed. Increased apoptosis was observed in RASF following Gal9 knock-down. We conclude that, unlike exogenous Gal9, endogenous Gal9 is protective against apoptosis and enhances synovial fibroblast viability suggesting that its role in RA is both pathogenic and pro-inflammatory.

Abstract

Galectin-9 (Gal9) has been postulated to have anti-inflammatory properties based on the ability of exogenous Gal9 to induce apoptosis in synovial fibroblasts in animal models of rheumatoid arthritis (RA). Here we aimed to assess the potential role of endogenous Galectins, including Gal9, in the inflammatory pathology of the RA synovium in humans. Firstly expression of Galectins 1-9 was determined in synovial fibroblasts (RASF) and dermal fibroblasts (DF) isolated from RA patients, the latter representing a non-inflamed site. We then further challenged the cells with pro-inflammatory TLR agonists and cytokines and assessed Galectin expression. Gal9 was found to be differentially and abundantly expressed in RASF compared to DF. Agonists of TLR3 and TLR4, along with IFNgamma were also found to induce Gal9 expression in RASF. siRNA was then used to knock-down Gal9 expression in RASF and the effects of this on apoptosis and cell viability were assessed. Increased apoptosis was observed in RASF following Gal9 knock-down. We conclude that, unlike exogenous Gal9, endogenous Gal9 is protective against apoptosis and enhances synovial fibroblast viability suggesting that its role in RA is both pathogenic and pro-inflammatory.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Rheumatology Clinic and Institute of Physical Medicine
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:27 August 2018
Deposited On:12 Sep 2018 13:43
Last Modified:30 Sep 2018 23:59
Publisher:Nature Publishing Group
ISSN:2045-2322
OA Status:Gold
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1038/s41598-018-31173-3
PubMed ID:30150656

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