Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose:
Patients with Systemic Lupus Erythematosus have an increased risk of cardiovascular disease (CVD). No specific targeted therapies for CVD in lupus exist and there are no in vitro models to study potential novel agents. Endothelial dysfunction, the earliest stage of vascular damage, is associated with interferon-alpha (IFNα) expression. It has been proposed that IFNα may act by impairing endothelial repair mechanisms. When compared to healthy controls, lupus patients have fewer circulating angiogenic cells (CAC) and endothelial progenitor cells (EPCs). Mixed EPC/CAC populations have been shown to be sensitive to IFNα, resulting in apoptosis and change in phenotype. We aimed to investigate the effects of IFNα2b on an in vitro model of angiogenesis/vascular repair.
Methods:
Peripheral blood mononuclear cells were obtained from healthy subjects and cultured on human fibronectin in endothelial growth media. Myeloid phenotype was confirmed by LDL uptake/lectin binding and expression of cell surface markers by RT-PCR. Cell survival in response to IFNα2b (0.01-10ng/ml) was determined by the number of LDL-uptake-positive cells at 7 days. An angiogenesis assay was used to study CAC function. Supernatant from CACs cultured for 7 days ± 10ng/ml IFNα2b was added to human aortic endothelial cells cultured on growth factor reduced Matrigel. Tubule formation was assessed at 14 hours using an automated computer algorithm. Mean values of the calculated network parameters were compared using 2-tailed t tests.
Results:
CACs expressed markers of both endothelial (CD31) and myeloid lineage (CD14, CD45). In addition, CACs strongly expressed the macrophage markers CD68, CD163 and CD206 suggesting an alternatively-activated (M2) macrophage phenotype. IFNα2b significantly reduced the number of CACs at day 7 in a dose-dependent manner (r2= -0.769, p<0.0001).
In co-culture with endothelial cells on Matrigel, CACs co-localised to the endothelial tubules but did not form tubule networks alone. CAC supernatant significantly increased the density of the tubule network when in terms of: total pixel area (27781 vs 36283, p=0.0065), number of branches (340.2 vs 510.6, p=0.0434), number of junctions (162.4 vs 241.1, p=0.0104) and number of closed loops within the network (21.8 vs 38.3, p=0.005). IFNα2b significantly reduced the number of closed loops (38.2 vs 24.1, p=0.0094). All other network parameters were reduced by IFNα2b but did not reach statistical significance.
Conclusion:
CACs are of myeloid lineage and have angiogenic capacity in vitro. CAC supernatant contains potent angiogenic factors which augment endothelial tubule networks. IFNα2b dramatically reduces the survival of CACs in vitro, resulting in reduced tubule network formation and may be a mechanism by which IFNα promotes vascular damage in SLE. Quantification of the angiogenic nature of CACs and the effects of IFNα2b, using a tubule formation assay, offers a potential in vitro model in which to study the effects of novel vasculoprotective agents in this patient population.
Disclosure:
J. A. Reynolds,
None;
D. W. Ray,
None;
T. O’Neill,
None;
M. Y. Alexander,
None;
I. N. Bruce,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/interferon-alpha-impairs-the-survival-and-function-of-circulating-angiogenic-cells-in-vitro-a-model-of-failed-endothelial-repair-in-sle/