Background/Purpose: Psoriatic arthritis (PsA) is characterised by an early vascular phase essential for pannus growth, immune responses and disease progression. Recently, numerous studies have highlighted the emerging importance of endothelial cell metabolism in controlling angiogenesis. Herein, we propose microRNA, miR-125, modulates EC bioenergetics and orchestrates joint angiogenesis as characterised by ex-vivo associations, in-vitro assays and novel CRISPR/cas9 in-vivo zebrafish models.

Methods: MiRNA levels were quantified in synovial tissue by RT-PCR and compared to macroscopic synovial vascularity and immunohistochemical analysis of angiogenic factors (FactorVIII/VEGF/ANG2). ECs (HMVEC) were transfected with anti-miR-125a for 24hr. Angiogenic mechanisms were quantified using tube formation assays, invasion by transwell matrigel chambers, migration by wound repair and gene expression (PFKFB3, HK2, GSK3A, G6PD by RT-PCR and western blot analysis. Real-time analysis of extracellular acidification rates (ECAR) and oxygen consumption rates (OCR) of anti-125 treated ECs was assessed using the XF-24 Extracellular Flux Analyzer (Seahorse Bioscience). To determine if altered metabolism is observed ex vivo, glycolysis/oxidative phosphorylation markers (GAPDH/PKM2/ GLUT1/ATP) were assessed by immunohistochemistry. In vivo, miR-125a CRISPR/Cas9-based knock-out zebrafish fluorescent reporter lines were generated and vascular development monitored. Finally, we examined the effect of blocking glycolysis using a small molecule, 3PO, which blocks PFKFB3, in miR-125a-/- ECs and zebrafish embryos.

Results: Synovial expression of miR-125 was significantly decreases in PsA versus OA synovial tissue, levels of which were associated with macroscopic and microscopic synovial vascularity (p<0.05). Decreased expression of miR-125a in HMVEC resulted in increased tube formation, invasion and migration properties (all p<0.05). Inhibition of miR-125 significantly decreased basal, maximal and spare respiratory capacity (p<0.009) with a concurrent decrease in ATP synthesis (p<0.08). Increased glycolysis was further supported by elevation of glycolytic genes, including PFKFB3. Elevated endothelial cell glycolysis was also demonstrated ex vivo with vascular synovial expression of glycolytic markers, PKM2, GLUT1 and ATP5B significantly increased in PsA compared to OA controls. 3PO significantly inhibited anti-miR-125a-induced mechanism. Finally, miR-125a^-/- embryos displayed increased vascular sprouting, effects normalised by the presence of the glycolytic inhibitor 3PO.

Conclusion: Decreased expression of miR-125 in PsA synovium and in-vivo models was strongly associated pro-angiogenic mechanisms. Elevated glycolysis following miR-125 inhibition enabled ECs to meet the increased energy and biosynthetic demands for new vessel formation. Correcting these miRNA deficiencies and their resulting metabolic shift, either by conventional pharmacological or as novel drug targets, may provide therapeutic benefit, especially in early disease.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/dysregulated-mir-125a-promotes-joint-angiogenesis-in-psoriatic-arthritis-through-altered-bioenergetics/