beta 1 integrin-extracellular matrix protein interaction modulates the migratory response to chemokine stimulation

It is well established that chemokines have a major role in the stimulation of cell movement on extracellular matrix (ECM) substrates. However, it is also clear that ECM substrates may influence the ability of cells to underg o migration. Using the migration chamber method, we assessed the migratory response of human embryonic kidney-293 (HEK) transfectant cells expressing the CC chemokine receptor 5 (CCR5) (HEK-CCR5) to stimulation by chemokines (macrophage inflamatory protein (MIP)-1alpha, MIP-1beta, and regulated on a ctivation normal-T cell expressed and secreted (RANTES)) on ECM substrates (collagen type I and fibronectin). Using filters coated with collagen (20 m ug/mL), results showed that the chemokines differed in their ability to eli cit cell movement according to the order MIP-1beta > RANTES approximately M IP-1alpha. In contrast, using filters coated with fibronectin (20 mug/mL), all three chemokines were similar in their ability to stimulate migration o f HEK-CCR5 cells. In addition, the migratory response with respect to the c oncentrations of ECM substrates appeared biphasic; thus, chemokine-stimulat ed cell movement was inhibited at high ECM concentrations (100 mug/mL). To determine the involvement of beta1 integrins, results showed that the migra tory response to chemokine stimulation on collagen was largely inhibited by monoclonal antibody (mAb) to alpha2beta1; however, complete inhibition req uired a combination of mAbs to alpha1beta1 and alpha2beta1. In comparison, migration on fibronectin was inhibited by mAb to alpha3beta1 and alpha5beta 1. Our results suggest that the migratory response to CCR5 stimulation may vary quantitatively with both the CCR5 ligand (MIP-1alpha, MIP-1beta, and R ANTES), as well as the nature and concentration of the ECM substrate involv ed.