Integrins inhibit LPS-induced DNA strand breakage in cultured lung endothelial cells

Collagen inhibits acute DNA strand breakage and apoptosis in sheep pulmonary artery endothelial cells (SPAEC) treated with lipopolysaccharide (LPS). Here we tested the ability of major basement membrane components, type IV collagen, laminin and fibronectin, and integrin ligands and anti-integrin antibodies to inhibit DNA breakage caused by LPS in SPAEC and BALB/c murine lung endothelial cells (MLEC). In situ labeling of DNA strand breaks with terminal deoxynucleotidyl transferase revealed similar DNA breakage in attached SPAEC and MLEC within 2 h after incubation with 1 mu g LPS/ml. Acute DNA strand breakage was reduced in cells plated on gelatin, type TV collagen, laminin, cellular fibronectin, or plasma fibronectin. DNA breakage was also suppressed by plating cells on surfaces coated with the integrin ligand hexapeptide, GRGDSP (40 mu g/cm(2)), but not with GRADSP. LPS-induced DNA strand breakage was inhibited in MLEC plated on surfaces coated with antibodies to murine alpha(5)- beta(1)-, or beta(3)- integrin subunits. Addition of anti-integrin antibodies, but not GRGDSP, to the medium above cell monolayers inhibited strand breakage. Despite similar acute DNA breakage, MLEC exhibited less detachment and apoptosis than SPAEC, consistent with a difference in the sensing or processing systems for apoptosis in these two cell types. These results demonstrate that extracellular matrices and integrin activation can inhibit the genotoxicity of LPS.