The role of cellular metabolism in Rheumatoid and Psoriatic Arthritis
Clare Cunningham1, Sebastian Fromm1, Margaret Dunne2, Sharon Ansboro1, Douglas Veale3, Sarah Wade1,3, Ursula Fearon1
1 Molecular Rheumatology, School of Medicine, Trinity College Dublin, Ireland. 2 Department of Surgery, Trinity Translational Medicine Institute, St. James's Hospital, Trinity College Dublin, Ireland. 3 Rheumatology EULAR Centre of Excellence, Centre for Arthritis & Rheumatic Diseases, University College Dublin, Ireland.
Rheumatoid Arthritis (RA) and Psoriatic Arthritis (PsA) share many common clinical manifestations, however significant pathogenic differences exist including differential vascular morphology, cellular infiltration and synovial hyperplasia.
The aim of this study was to compare the functional and metabolic profiles of RA and PsA synovial fibroblast cells (SFC) and to determine their effect on endothelial cell (EC) function.
RA and PsA primary SFC were grown to confluence, supernatants were harvested and termed ‘conditioned media’ (CM). The metabolic profiles of RA and PsA SFC were analysed using the XF96 Extracellular Flux Analyzer. SFC migration and invasion were determined by wound repair and transwell invasion assays. HUVEC were cultured in the presence of RA or PsA SFC-CM (20%). Matrigel tube-formation, wound repair and PBMC adhesion assays were performed on HUVEC. HUVEC cell surface expression of ICAM, VCAM and E-Selectin was assessed by flow-cytometry. Transcriptome analysis was quantified by real-time PCR. Finally, a MSD-multiplex angiogenic assay was performed in RA and PsA SFC supernatants.
RA SFC displayed increased migratory capacity and invasiveness compared to PsA SFC. A higher oxygen consumption rate (OCR)/extracellular acidification rate (ECAR) ratio were observed in RA SFC. In parallel, IL-6,-IL-8 and the glycolytic markers, GLUT1/3, HK2, PKM1/2, PDK2 and LDHA were higher in RA vs PsA SFC (p<0.05). Transcriptome analysis showed strong upregulation of the pro-angiogenic machinery in PsA SFC-CM-primed HUVEC compared to RA SFC-CM. PsA SFC-CM significantly induced HUVEC tube formation, junction formation and segment number compared to RA SFC-CM (p<0.05). Furthermore, PsA SFC-CM induced HUVEC migration, VEGFA, ICAM-1 and MMP3 mRNA expression (all p<0.05). A significant increase in PBMC adhesion, expression of VCAM-1, ICAM-1 and E-Selectin were demonstrated in PsA SFC-CM-primed HUVEC compared to RA SFC-CM (all p<0.05). Finally, VEGF, TSLP, Flt-1 and Tie-2 expression was significantly elevated in PsA SFC-CM compared to RA-SFC-CM (p<0.05).
Consistent with clinical observations, RASFC have a greater migratory and invasive capacity than PsA SFC. In contrast, the PsA joint microenvironment induces a more pro-angiogenic phenotype than the RA microenvironment. Further understanding of the underlying differential molecular mechanisms in RA and PsA may led to better treatment strategies.