Anti-GRP78 autoantibodies induce endothelial cell activation and accelerate the development of atherosclerotic lesions
Elizabeth D. Crane, … , Wadih Arap, Richard C. Austin
Elizabeth D. Crane, … , Wadih Arap, Richard C. Austin
Published December 20, 2018
Citation Information: JCI Insight. 2018;3(24):e99363. https://doi.org/10.1172/jci.insight.99363.
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Research Article

Anti-GRP78 autoantibodies induce endothelial cell activation and accelerate the development of atherosclerotic lesions

Abstract

The 78-kDa glucose-regulated protein (GRP78) is an ER molecular chaperone that aids in protein folding and secretion. However, pathological conditions that cause ER stress can promote the relocalization of GRP78 to the cell surface (csGRP78), where it acts as a signaling receptor to promote cancer progression. csGRP78 also possesses antigenic properties, leading to the production of anti-GRP78 autoantibodies, which contribute to tumor growth. In contrast, the presence and role of anti-GRP78 autoantibodies in atherosclerosis is unknown. Here, we show that atherosclerotic-prone ApoE–/– mice develop circulating anti-GRP78 autoantibodies that bind to csGRP78 on lesion-resident endothelial cells. Moreover, GRP78-immunized ApoE–/– mice exhibit a marked increase in circulating anti-GRP78 autoantibody titers that correlated with accelerated lesion growth. Mechanistically, engagement of anti-GRP78 autoantibodies with csGRP78 on human endothelial cells activated NF-κB, thereby inducing the expression of ICAM-1 and VCAM-1, a process blocked by NF-κB inhibitors. Disrupting the autoantibody/csGRP78 complex with enoxaparin, a low-molecular-weight heparin, reduced the expression of adhesion molecules and attenuated lesion growth. In conclusion, anti-GRP78 autoantibodies play a crucial role in atherosclerosis development, and disruption of the interaction between anti-GRP78 autoantibodies and csGRP78 represents a therapeutic strategy.

Authors

Elizabeth D. Crane, Ali A. Al-Hashimi, Jack Chen, Edward G. Lynn, Kevin Doyoon Won, Šárka Lhoták, Magda Naeim, Khrystyna Platko, Paul Lebeau, Jae Hyun Byun, Bobby Shayegan, Joan C. Krepinsky, Katey J. Rayner, Serena Marchiò, Renata Pasqualini, Wadih Arap, Richard C. Austin

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Figure 6

Anti-GRP78 autoantibodies induce NF-κB p65 nuclear localization.

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Anti-GRP78 autoantibodies induce NF-κB p65 nuclear localization. (A) HAE...
(A) HAECs were pretreated with either enoxaparin (Enox, 50 μg/ml) or TPCA-1 (1 μM) for 6 hours prior to treatment with either human IgG (30 μg/ml) or purified anti-GRP78 autoantibody (AA, 30 μg/ml) for 12 hours. Representative images of immunofluorescence staining of NF-κB p65 subunit localization are presented. Original magnification, ×20. (B) Quantification of positive p65 nuclear staining. NF-κB p65 is stained red (Cy5-conjugated secondary antibody). Nuclei were counterstained with DAPI (n = 10 per group). *P < 0.05 versus IgG. #P < 0.05 versus anti-GRP78 autoantibody, ANOVA. (C) Anti-GRP78 autoantibody treatment substantially activates the NF-κB classical canonical pathway but not the alternative pathway, as determined by immunoblotting for IκBα and p100, respectively. HAECs were treated with human IgG (IgG, 30 μg/ml) or purified anti-GRP78 autoantibodies (AA, 30 μg/ml) for 6 hours. Total cell lysate were subjected to Western blotting for detection of p100 NF-κB subunit or IκBα. Blots were also immunostained for β-actin as a protein loading control. Quantification of immunoblots is expressed as fold change. All values are represented as mean ± SD (n = 4–6 per group). *P < 0.05 versus IgG, 2-tailed t test.