RA-Associated Autoantibodies Promote Synovial Fibroblasts Migration and Adhesion through a Peptidylarginine Deiminases (PAD) Dependent Pathway

Meng Sun¹, Vijay Joshua², Aase Haj Hensvold^1,3, Khaled Amara⁴, Vivianne Malmström¹, Heidi Wähämaa¹ and Anca I Catrina¹, ¹Rheumatology Unit, Department of Medicine, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden, ²Unit of Rheumatology, Department of Medicine Solna, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden, ³Rheumatology Unit, Department of Medicine, Solna, Karolinska Institute, Stockholm, Sweden, Stockholm, Sweden, ⁴Rheumatology Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden

Meeting: 2015 ACR/ARHP Annual Meeting

Date of first publication: September 29, 2015

Keywords: anti-CCP antibodies, fibroblasts and rheumatoid arthritis (RA)

Session Information

Date: Tuesday, November 10, 2015

Title: Biology and Pathology of Bone and Joint: Bone Remodeling and Metabolism

Session Type: ACR Poster Session C

Session Time: 9:00AM-11:00AM

Background/Purpose:

The presence of anti-citrullinated proteins antibodies (ACPAs) in RA is associated with a more aggressive disease phenotype and bone destruction. Synovial fibroblasts (SFs) are key players of both synovial inflammation and bone destruction in rheumatoid arthritis (RA). We aimed to invesigate the effect of ACPAs on synovial fibroblasts.

Methods:

SFs were isolated from synovial tissue of RA patients (RA SFs) by enzymatic digestion. ACPA positive and negative IgGs were separated from plasma of RA patients and monoclonal ACPAs were generated from synovial fluid single B-cells. The effect of polyclonal and monoclonal ACPAs and appropriate negative controls was tested in migration scratch assays and adhesion assays by xCELLigence System Real-Time Cell Analyzer (ACEA bioscience). Light microscopy images were analyzed using NIH ImageJ to calculate migration index. Impedance-based signals were monitored every minute for1 hour, every 5 minutes up to 13 hours and every 15 minutes up to 36 hours. Inhibition of phosphoinositide 3-kinase (PI3K), G-protein coupled receptors, focal adhesion kinase (FAK) and peptidylarginine deiminases (PAD) inhibitor were tested in migration scratch assays in the presence or absence of the antibodies.

Results:

Polyclonal ACPAs but not others IgGs than ACPAs induced a 2.6±0.5 (mean±SD) fold increase in RASFs migration (p<0.05). ACPAs also induced a significant fold increase in RASFs adhesion of 1.3±0.1 (p<0.05). Similar effects were observed with one (D10), but not others two monoclonal ACPAs, with a fold increase of 2.4±0.4 (p<0.05) in migration index and 1.2±0.1 (p<0.05) in adhesion index.

G-protein coupled receptor blockade completely abolished ACPAs effects on RA SFs migration, while PI3K blockade decreased migration to a residual fold increase of 1.4±0.4 (mean±SD) and FAK blockade had no effect. Irreversible PAD blockade and pre-incubation of antibodies with citrulinated fibrinogen abolished ACPAs effects. No difference in either cytotoxicity or proliferation rate were observed between different treatments.

Conclusion:

ACPAs directly mediate fibroblast migration and adhesion through a novel G protein coupled receptor and PAD-dependent mechanism. Our findings provide novel insights into the link between adaptive immunity and synovial fibroblasts.

Disclosure: M. Sun, None; V. Joshua, None; A. H. Hensvold, None; K. Amara, None; V. Malmström, None; H. Wähämaa, None; A. I. Catrina, None.

To cite this abstract in AMA style:

Sun M, Joshua V, Hensvold AH, Amara K, Malmström V, Wähämaa H, Catrina AI. RA-Associated Autoantibodies Promote Synovial Fibroblasts Migration and Adhesion through a Peptidylarginine Deiminases (PAD) Dependent Pathway [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/ra-associated-autoantibodies-promote-synovial-fibroblasts-migration-and-adhesion-through-a-peptidylarginine-deiminases-pad-dependent-pathway/. Accessed .

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