Abstract 423: CC-Chemokine Class Inhibition Attenuates Inflammatory Induced Pathological Angiogenesis Whilst Preserving Ischaemia 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. Increasing evidence suggests the CC-chemokine class promote inflammatory-driven angiogenesis but, in contrast, have no role in hypoxia-driven angiogenesis. Inhibition of the CC-chemokine class may therefore regulate angiogenesis differently depending on the pathophysiological context.

Aim: Using the broad-spectrum CC-chemokine inhibitor ‘35K’, compare the role of the CC-chemokine class in inflammatory versus ischaemia driven angiogenesis.

Results: Adenoviruses expressing GFP (AdGFP) or 35K (Ad35K) were injected into mice 3 days prior surgery. Using the murine femoral cuff model of inflammatory angiogenesis, we found a significant decrease in adventitial capillaries (39.7%) and arterioles (75.5%) in the Ad35K group compared to the AdGFP controls, p<0.05. Ad35K mice also had significantly less macrophages (CD68, 32.5%). In contrast, 35K had no effect on markers of neovascularisation including: blood flow recovery and hindlimb capillary density, in the murine hind limb ischaemia model. Consistent with our in vivo findings, in vitro angiogenic assays with endothelial cells, revealed that 35K protein had inhibitory effects on inflammation-induced tubule formation (95.8%), proliferation (88.3%) and migration (15.8%), p<0.05. In hypoxia the inhibitory effects of 35K were more modest for tubule formation (45.2%) and proliferation (43.8%), and migration was completely preserved. Under inflammatory conditions 35K inhibited VEGF (53.4%) and HIF-1α (87.3%) cell protein levels, yet in hypoxia 35K had no effect on VEGF and had a more modest inhibitory effect on HIF-1α (65.4%).

Conclusion: Broad-spectrum CC-chemokine inhibition by 35K inhibits inflammation-induced angiogenesis, whilst preserving ischaemia-driven angiogenesis in vitro and in vivo. CC-Chemokine inhibition may be therapeutic strategy to reduce pathological angiogenic diseases without the severe side effects of current therapies caused by complete inhibition in both contexts.