Inhibition of IkB Kinase-IKK Complex of Canonical NF-κB Pathway in Antiphospholipid Antibody-Mediated Endothelial Cell Activation

Rohan Willis¹, Elizabeth Papalardo ¹, Mohammad Jamaluddin ¹, Zurina Romay-Penabad ¹, Alvaro Schleh ¹, Allan Brasier ¹ and Emilio B Gonzalez ², ¹University of Texas Medical Branch, Galveston, TX, ²University of Texas Medical Branch, Galveston

Meeting: 2019 ACR/ARP Annual Meeting

Keywords: antiphospholipid syndrome, Cell Signaling, endothelial cells and antiphospholipid antibodies, therapeutic targeting

Session Information

Date: Sunday, November 10, 2019

Session Title: Cytokines & Cell Trafficking Poster

Session Type: Poster Session (Sunday)

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

Background/Purpose: Antiphospholipid antibodies (aPL) activate several target cell types leading to inflammatory damage and thrombosis in the antiphospholipid syndrome (APS). NF-κB activation is essential for inducing this inflammatory phenotype but there is limited information on the role of the canonical vs non-canonical NF-κB activation pathways in APS and the inhibition of these pathways as a possible therapeutic strategy in APS. We sought to determine the efficacy of specific inhibitors of the regulatory IκB kinase complex (IKK), which is responsible for initiating nuclear translocation of NF-κB, in ameliorating the effects of aPL.

Methods: Whole IgG fractions were purified from normal (IgG-NHS) and primary APS (IgG-APS) patients by ammonium sulphate precipitation followed by DEAE sepharose chromatography. Increasing doses of purified whole IgG-APS and control IgG-NHS fractions were used to treat human umbilical vein endothelial cells (HUVEC) (100-400μg/ml). Quantitative RT-PCR was used to measure E-selectin (E-sel), tissue factor(TF), interleukin (IL)-6 and IL-8 mRNA expression and western blot was used to evaluate the time course of NF-κB activation in treated HUVEC identifying various subunits over 4-hours post treatment (at time points 0, 15, 30, 60, 120, 240 and 480 minutes). The effectiveness of specific IKK inhibitors Bay-11-7082 and BMS-345541 were evaluated.

Results: IgG-APS increased pro-inflammatory cytokine expression in a dose dependent manner, with a maximum mRNA fold change ranging from 4-18 times over controls. Over the 4-hour time-course cytoplasmic expression of IκBα decreased and nuclear expression of RelA, p50 (strong) and p52, p105 (weak) subunits increased in response to aPL treatment (peaks at 30 to 60 minutes), indicating strong activation via the canonical NF-kB pathway. BMS and Bay-11 significantly inhibited cytokine expression 2.5 to 3.5 fold in aPL-treated HUVEC.

Conclusion: The canonical NF-kB pathway is essential for aPL-medicated EC activation in at least a portion of APS patients. Accordingly, specific IKK inhibitors may prove useful in ameliorating aPL-mediated inflammation in these patients.

Disclosure: R. Willis, None; E. Papalardo, None; M. Jamaluddin, None; Z. Romay-Penabad, None; A. Schleh, None; A. Brasier, None; E. Gonzalez, None.

To cite this abstract in AMA style:

Willis R, Papalardo E, Jamaluddin M, Romay-Penabad Z, Schleh A, Brasier A, Gonzalez E. Inhibition of IkB Kinase-IKK Complex of Canonical NF-κB Pathway in Antiphospholipid Antibody-Mediated Endothelial Cell Activation [abstract]. Arthritis Rheumatol. 2019; 71 (suppl 10). https://acrabstracts.org/abstract/inhibition-of-ikb-kinase-ikk-complex-of-canonical-nf-%ce%bab-pathway-in-antiphospholipid-antibody-mediated-endothelial-cell-activation/. Accessed March 27, 2023.

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