Novel Functional Role of inflammatory cytokines, IL- 1beta, IL-6, and TNFalpha in angiogenesis revealed by analysis of their knockout mice

背景：血管内皮祖细胞(EPC)被发现在局部缺血时能被动员到成人外周血中，在缺血区新生血管中发挥重要作用。此外，已发现血管内皮生长因子可诱导骨髓源性EPC的动员。同时，我们也报道了IL-1β(IL-1β)上调心脏血管内皮生长因子及其受体-2的表达，增加了IL-1β在血管内皮生长因子介导的血管新生中发挥重要作用的可能性。在这项研究中，我们利用IL-1β基因敲除(-/-)小鼠研究了缺血诱导新生血管的细胞机制。方法和结果：1)与野生型小鼠相比，IL-1β-/-小鼠缺血后肢血液灌流恢复明显受损(下降43%)。CD31+血管数和Ki-67+新生毛细血管数显著减少(P<0.01)，分别减少44%和68%。2)IL-1β表达定位于…的毛细血管四肢肌肉充血。缺血诱导的α及其受体VEGFR-2在IL-1β-/-小鼠中的表达受到明显抑制。3)肢体缺血可引起野生型小鼠外周血中CD34-/B220-/CD3-/Flk1+造血干细胞数量增加(占总核细胞的1.22%)，而IL-1β-/-小鼠仅增加0.09%。4)野生型小鼠注射IL-1β蛋白后，外周血中CD34~-/B220~-/CD3~-/Flk1~+细胞比例由0.03%增加到0.7%，内皮细胞数量增加。这种IL-1β介导的细胞数量增加可被联合注射抗血管内皮生长因子抗体所阻断。5)CD34^-/B220^-CD3^-Flk1^+细胞在体内外均可反式分化为表达eNOS和CD31的内皮细胞。结论：本研究证实了炎性细胞因子IL-1β在肢体缺血中促进新生毛细血管形成的关键作用。IL-1β介导的缺氧诱导因子-1α、血管内皮生长因子及其受体的表达或CD34-Flk-1+内皮祖细胞的动员与IL-1-β诱导的血管生成密切相关。较少

Background : Endothelial progenitor cells (EPC) have been found to mobilize into adult peripheral blood in response to regional ischemia, and play a critical role in neovascularization in ischemic region. Also VEGF have been found to induce the mobilization of bone marrow derived EPC. Meanwhile we have reported that interleukin-1 beta (IL-1β) up-regulates cardiac expression of vascular endothelial growth factor (VEGF) and VEGF receptor-2, raising the possibility that IL-1β plays a important role in VEGF-mediated neovascularization. In this study, we examined the cellular mechanism for ischemia-induced neovascularization using IL-1β knockout (-/-) mice. Method and Result : 1)Recovery of blood perfusion in ischemic hindlimb in IL-1β-/- mice was markedly (43% decrease) impaired as compared with the wild type mice. CD31+ vessel numbers and Ki-67+ neo-capillaries were significantly (p<0.01) decreased 44% and 68%, respectively. 2)IL-1β expression was localized in the capillary vessels in isc … More hemic limb muscles. Ischemia-induced expression of HIF1α, VEGF and its receptor VEGFR-2 was markedly inhibited in the IL-1β-/-mice. 3)Hindlimb ischemia induced an increase (1.22% out of total nuclear cell) in CD34^-/B220^-/CD3^-/Flk1^+ hematopoietic stem cell population in peripheral blood in the wild type mice, whereas in the IL-1β-/-mice such increase was only 0.09%. 4)Injection of IL-1β protein into the wild-type mice markedly increased the ratio of the CD34^-/B220^-/CD3^-/Flk1^+ cell population (from 0.03 to 0.7%) in the peripheral blood associated with an increase in the number of endothelial cells. Such IL-1β-mediated increases in cell numbers were blocked by co-injection of anti-VEGF antibody. 5)CD34^-/B220^-CD3^-Flk1^+ cells trans-differentiated into eNOS- and CD31-expressing endothelial cells in vitro and in vivo. Conclusion : In this study demonstrates the critical role of inflammatory cytokine IL-1β to enhance neo-capillary formation in limb ischemia. IL-1β-mediated expression of HIF-1α, VEGF and its receptor, or mobilization of CD34-Flk-1+ endothelial precursor cells is closely involved in IL1-β-induced neovascularization. Less