Antiangiogenic effect of interleukin-10 in ischemia-induced angiogenesis in mice hindlimb

Ischemia induces both hypoxia and inflammation that trigger angiogenesis. T he inflammatory reaction is modulated by production of anti-inflammatory cy tokines. This study examined the potential role of a major anti-inflammator y cytokine, interleukin (IL)-10, on angiogenesis in a model of surgically i nduced hindlimb ischemia. Ischemia was produced by artery femoral occlusion in both C57BL/6J IL-10(+/+) and IL-10(-/-) mice. After 28 days, angiogenes is was quantified by microangiography, capillary, and arteriole density mea surement and laser Doppler perfusion imaging. The protein levels of IT,-10 and vascular endothelial growth factor (VEGF) were determined by Western bl ot analysis in hindlimbs. IL-10 was markedly expressed in the ischemic hind limb of IL-10(+/+) mice. Angiogenesis in the ischemic hindlimb was signific antly increased in IL-10(-/-) compared with IL-10(+/+) mice. Indeed, angiog raphic data showed that vessel density in the ischemic leg was 10.2+/-0.1% and 5.7+/-0.4% in IL-10(-/-) and IL-10(+/+) mice, respectively (P<0.01). Th is corresponded to improved ischemic/nonischenic leg perfusion ratio by 1.4 -fold in IL-10(-/-) mice compared with IL-10(+/+) mice (0.87+/-0.05 versus 0.63+/-0.01, respectively; P<0.01). Revascularization was associated with a 1.8-fold increase in tissue VEGF protein level in IL-10(-/-) mice compared with IL-10(+/+) mice (P<0.01). In vivo electrotransfer of murine IL-10 cDN A in IL-10-/- mice significantly inhibited both the angiogenic process and the rise in VEGF protein level observed in IL-10-/- mice. No changes in ves sel density or VEGF content were observed in the nonischemic hindlimb. Thes e findings underscore the antiangiogenic effect of IL-10 associated with th e downregulation of VEGF expression and suggest a role for the inflammatory balance in the modulation of ischemia-induced angiogenesis.