Abstract 566: Broad-Spectrum Chemokine Inhibition Blocks Inflammation-Induced Pathological Angiogenesis but Preserves Hypoxia-Driven Physiological Angiogenesis

Abstract

Introduction: Angiogenesis is critical for survival and in the regenerative response to tissue hypoxia. An imbalance in its regulation causes excessive angiogenesis, exacerbating inflammatory diseases such as cancer and atherosclerosis. Chemokines from the CC-chemokine class are increasingly implicated in the regulation of inflammatory pathological angiogenesis but, in contrast, have a minimal role in hypoxia-driven physiological angiogenesis. Inhibition of CC-chemokines may therefore differentially regulate angiogenesis depending on the pathophysiological context. The ‘35K’ protein uniquely inhibits the CC chemokine class and does not affect chemokines from other classes. Aim: To determine the effect of CC-chemokine inhibition with 35K on inflammation-induced angiogenesis and hypoxia-driven angiogenesis using human coronary artery endothelial cells (EC) in in vitro angiogenic functional assays. Results: Matrigel tubule formation was strikingly inhibited (95.8%, p<0.001) by 35K (50nM) under the inflammatory stimuli of macrophage conditioned media. The addition of 35K also reduced inflammation-induced proliferation by 88.3% (p<0.001). Furthermore, we found the addition of 35K suppressed inflammation stimulated EC migration speed by 15.8% (p<0.05). By contrast, in hypoxia, 35K (50nM) reduced tubule formation by 45.2% (p<0.01), indicating a relative preservation of tubulogenesis in hypoxia compared to inflammation. Consistent with this, in hypoxia, 35K reduced proliferation by 43.8% (p<0.05). Moreover, the speed of EC migration was completely preserved under hypoxic conditions following the addition of 35K. Mechanistic studies supported our functional observations. Angiogenic growth factor, VEGF, was inhibited (53.4%) by 35K (200nM) under inflammatory conditions yet was augmented in hypoxia (31.5%). 35K also decreased key angiogenesis transcription factors, p65 (37.3%) and HIF-1α (87.3%) in inflammation. Conclusion: Broad-spectrum chemokine inhibition by 35K blocks inflammation-induced angiogenic processes, whilst preserving hypoxia-driven angiogenesis. This may present as a therapeutic strategy to reduce pathological angiogenic disease, without the severe side effects of current therapies.