HYPOCHLOROUS ACID DISRUPTS THE ADHESIVE PROPERTIES OF SUBENDOTHELIAL MATRIX

We have investigated whether the cell adhesion-promoting properties of the subendothelial matrix are affected by exposure to neutrophil-deri ved oxidants. Native subendothelial matrix was exposed to increasing d oses of H2O2 in the presence of myeloperoxidase and Cl- or to reagent hypochlorous acid (HOCl). Increasing doses of either oxidant system re sulted in progressive loss in the adhesive propel-ties of the matrix, and phase contrast microscopy showed that the cells failed to attach t o and spread on the oxidant-treated surface, When cells were replated on the treated matrix in the presence of 20% serum, they did attach, b ut showed abnormal spreading and morphology in longer-term culture, In a modified ELISA system, binding of antibodies specific to fibronecti n, thrombospondin and laminin was also disrupted by prior exposure of the matrix to HOCl. Of these components, the cell-binding region of fi bronectin was most affected by HOCl, thrombospondin and laminin were l ess sensitive, and the collagen binding region of fibronectin was the most resistant. SDS-PAGE of S-35-labelled subendothelial matrix protei ns indicated that there was no major irreversible crosslink formation or fragmentation after exposure to HOCl or the myeloperoxidase system, although formation of disulfides is quite likely. (C) 1997 Elsevier S cience Inc.