127. Active Takayasu Arteritis is associated with plasma and cellular measures of endothelial dysfunction
Creators: name: Maughan1, Robert
name: Peverelli1, Marta
name: Porter1, Andrew
name: Malone2, Kerri
name: Kiprianos1, Allan
name: Pericleous1, Charis
name: Mason1, Justin
Publisher: name: Zenodo
Year: 2022
Subjects: Vasculitis
ANCA
Abstracts
Giant Cell Arthritis
MPA
GPA
EGPA
Takayasu
IgA vasculitis

description: <strong>Background:</strong> Takayasu Arteritis (TA) is a form of Large Vessel Vasculitis (LVV) characterised by granulomatous inflammatory lesions affecting the aorta and its branches. The accurate assessment of disease activity and progression can be a major challenge in TA. An improved undertanding of disease pathogenesis is required to facilitate the development of novel tools to aid clinical decision-making. Due to its central role in vascular health and disease, we hypothesise that endothelial dysfunction is an important factor in TA disease progression. To explore this concept, we first investigated the association between plasma markers of endothelial dysfunction and disease activity. Second, we sought to understand the molecular basis of endothelial dysfunction in TA by studying blood endothelial cells derived from TA patients. <strong>Methods:</strong> A panel of endothelial dysfunction markers including soluble (s)VCAM1, sICAM1, sE-selectin, sP-selectin, Plasminogen Activator Inhibitor 1 (PAI-1), soluble thrombomodulin (sTM), von Willebrand Factor (vWF) and the vWF cleaving protease ADAMTS13, were measured by ELISA in the plasma of 135 TA patients and 52 healthy control (HC) subjects matched for age and sex. TA patients were classified as active (n=42), grumbling (n=22) or stable (n=71) through assessment of clinical and radiological features, physician impression, CRP, ESR and Indian Takayasu clinical Activity Score (ITAS). The established TA disease activity marker pentraxin 3 (PTX3) was also quantified to provide additional assessment of disease activity status. For endothelial cell analyses, endothelial colony-forming cells (ECFC) were generated from PBMC of 6 patients with active TA and 5 HC. After confirmation of endothelial purity by flow cytometry (CD31<sup>+</sup>/CD144<sup>+</sup>/CD146<sup>+</sup>/CD45<sup>–</sup>/CD14<sup>–</sup>), ECFC phenotype was interrogated by pro-inflammatory activation assays and by bulk RNA-seq analysis. Plasma markers were analysed using non-parametric statistical methods and data is presented as median [IQR]. For TNFα dose response experiments, non-linear least squares regression analysis was applied. After quality control and mapping (Salmon), RNA-seq data was analysed for differential expression using EdgeR. P&gt;0.05 was considered significant. <strong>Results:</strong> Plasma levels of PTX3, sE-selectin, sP-selectin and PAI-1 were elevated in active TA patients in comparison to HC (+2.3 [1.5-4.2] fold, p&lt;0.0001; +1.2 [0.9-1.8] fold, p=0.026; +1.5 [1.1-1.9] fold, p&lt;0.0001; +2.3 [1.1-4.6], p=0.004 respectively, Fig 1A). Furthermore, concentrations of sP-selectin correlated with ITAS and PTX3 (rho= 0.19, p=0.033; rho=0.4, p&lt;0.0001 respectively). Levels of sVCAM1, sICAM1, VWF, sTM were not increased in active TA. ECFCs derived from patients with active TA demonstrated significantly higher sensitivity to TNFα-mediated induction of VCAM1 and E-selectin mRNA in comparison to HC (p=0.0009 and p=0.0464 respectively, Fig 1B). Consistent with this pro-inflammatory phenotype, RNA-seq analysis of TA ECFC revealed increased expression of inflammation and immunoregulatory genes including E-selectin, ZNF580, MICA, TNFSF4, and IL7R. <strong>Conclusions:</strong> Herein, we describe a pattern of endothelial dysfunction in active TA which includes increased plasma levels of soluble cell adhesion molecules E-selectin and P-selectin and the pleiotropic fibrinolytic regulator PAI-1. In particular, P-selectin levels may represent a useful, novel disease activity marker. Plasma findings were consistent with the pro-inflammatory phenotype observed in ECFCs derived from patients with active TA. Future work will aim to understand how this molecular pattern of endothelial dysfunction contributes to TA disease progression. <strong>Disclosures:</strong> RM has no disclosures. <strong>Figure 1</strong>: Assessment of plasma and cellular endothelial dysfunction parameters in active Takayasu Arteritis