Minimally modified low-density lipoprotein induces monocyte adhesion to endothelial connecting segment-1 by activating β1 integrin
Peggy T. Shih, … , Judith A. Berliner, Devendra K. Vora
Peggy T. Shih, … , Judith A. Berliner, Devendra K. Vora
Published March 1, 1999
Citation Information: J Clin Invest. 1999;103(5):613-625. https://doi.org/10.1172/JCI5710.
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Article

Minimally modified low-density lipoprotein induces monocyte adhesion to endothelial connecting segment-1 by activating β1 integrin

Abstract

We have shown previously that treatment of human aortic endothelial cells (HAECs) with minimally modified low-density lipoprotein (MM-LDL) induces monocyte but not neutrophil binding. This monocyte binding was not mediated by endothelial E-selectin, P-selectin, vascular cell adhesion molecule-I, or intercellular adhesion molecule-I, suggesting an alternative monocyte-specific adhesion molecule. We now show that moncytic α4β1 integrins mediate binding to MM-LDL-treated endothelial cells. We present data suggesting that the expression of the connecting segment-1 (CS-1) domain of fibronectin (FN) is induced on the apical surface of HAEC by MM-LDL and is the endothelial α4β1 ligand in MM-LDL-treated cells. Although the levels of CS-1 mRNA and protein were not increased, we show that MM-LDL treatment causes deposition of FN on the apical surface by activation of β1integrins, particularly those associated with α5 integrins.Activation of β1 by antibody 8A2 also induced CS-1-mediated monocyte binding. Confocal microscopy demonstrated the activated β1 and CS-1colocalize in concentrated filamentous patches on the apical surface of HAEC. Both anti-CS-1 and an antibody to activated β1 showed increased staining on the luminal endothelium of human coronary lesions with active monocyte entry. These results suggest the importance of these integrin ligand interactions in human atherosclerosis.

Authors

Peggy T. Shih, Mariano J. Elices, Zhuang T. Fang, Tatiana P. Ugarova, Dana Strahl, Mary C. Territo, Joy S. Frank, Nicholas L. Kovach, Carlos Cabanas, Judith A. Berliner, Devendra K. Vora

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Figure 1

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Western blot analysis of 90.45 and FN antibody binding to plasma FN and ...
Western blot analysis of 90.45 and FN antibody binding to plasma FN and cell lysates. Plasma FN (5 μg/lane) was electrophoresed and transferred onto nitrocellulose. Membranes were probed with polyclonal FN (lane 1), monoclonal FN (lane 2), and 90.45 (lane 3) antibodies. All three antibodies recognized, to varying intensities, pFN to be a single band at ∼220 kDa (a). In a chymotryptic digest of pFN (5 μg/ lane), the 90.45 antibody recognized a band at ∼66 kDa (lane 4) with an intensity greater than its recognition of intact pFN (compare lanes 3 and 4) (a). To compare the pattern of antibodies, whole cell lysates prepared in RIPA lysis buffer were separated and transferred onto nitrocellulose. The polyclonal FN (lane 5), monoclonal FN (lane 6), 90.45 (lane 7), and 7E5 antibodies (lane 8) detected two bands of 220 and 190 kDa. For the monoclonal and polyclonal FN antibodies, the 220-kDa band stained with a greater intensity (lanes 5 and 6) than the 190-kDa band, whereas the CS-1 and 7E5 antibodies recognized the 190-kDa band better than the 220-kDa band (lanes 7 and 8) (b). FN, fibronectin; RIPA, radioimmunoprecipitation assay.