Methe Heiko, Groothuis Adam, Sayegh Mohamed H, Edelman Elazer R
Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 77 Massachusetts Ave., Bldg 56-322, Cambridge, MA 02139, USA.
FASEB J. 2007 May;21(7):1515-26. doi: 10.1096/fj.06-7051com. Epub 2007 Jan 30.
Endothelial integrity regulates vascular tone, luminal patency, and the immune reactivity to tissue grafts. Endothelial dysfunction is the first marker and site of disease initiation and severity. It has long been known that endothelial biochemical function is density dependent, and we have recently shown that endothelial immunobiology is anchorage dependent. Matrix-embedded endothelial cells (EC) establish a controlled anchorage state and are not only immune protected but also induce a system immune protective state. We now define this aspect of vascular and immune biology in detail. The in vitro immune response of allogeneic splenocytes (proliferation, lytic activity, and cytokine expression) on exposure to aortic EC was significantly reduced if EC were embedded within three-dimensional collagen matrices (3D-EC; P<0.005) to an even greater extent than EC that had reached confluence as monolayers on tissue culture plates (EC-TCPS). Splenocyte reactivity was enhanced with repeated exposure to EC-TCPS but minimally if preexposed to 3D-EC (P<0.002). 3D-EC induced significantly greater differentiation of splenocytes into CD4+ CD25+ Foxp3+ regulatory T cells than EC-TCPS (P<0.02). The reduced response to 3D-EC and potential protective effect to subsequent exposure were confirmed in vivo. Repeated exposure of immune-competent mice to injections of xenogeneic EC-TCPS induced vigorous host immunity. In contrast, prior implantation of 3D-EC induced hyporesponsiveness toward subsequent injection of EC-TCPS with reduced humoral response, decreased lytic activity, and lower frequency of effector splenocytes (P<0.001). EC interaction with its matrix determines phenotype, viability, and biosecretory potential. We now show that this microenvironmental interaction also influences endothelial-mediated activation of allo- and xenogeneic immune cells. 3D matrix-embedding limits the ability of EC to initiate adaptive immunity, and initial exposure to 3D-EC confers hyporesponsiveness to subsequent exposure to immunogeneic EC. These effects transcended the traditional control that confluence imposes on EC and reflects perhaps even higher order control. Our findings might offer novel insights to endothelial-mediated diseases and potential cell-based therapies.
内皮完整性调节血管张力、管腔通畅性以及对组织移植物的免疫反应性。内皮功能障碍是疾病起始和严重程度的首个标志物及位点。长期以来人们已知内皮生化功能是密度依赖性的，并且我们最近表明内皮免疫生物学是锚定依赖性的。基质包埋的内皮细胞（EC）建立了一种可控的锚定状态，不仅受到免疫保护，还能诱导一种系统免疫保护状态。我们现在详细定义血管和免疫生物学的这一方面。如果将EC包埋在三维胶原基质（3D - EC）中，同种异体脾细胞在暴露于主动脉EC时的体外免疫反应（增殖、裂解活性和细胞因子表达）会显著降低（P < 0.005），其降低程度甚至比在组织培养板上形成单层汇合的EC（EC - TCPS）还要大。脾细胞反应性在反复暴露于EC - TCPS时增强，但在预先暴露于3D - EC时增强极小（P < 0.002）。与EC - TCPS相比，3D - EC诱导脾细胞显著更多地分化为CD4 + CD25 + Foxp3 + 调节性T细胞（P < 0.02）。在体内证实了对3D - EC的反应降低以及对后续暴露的潜在保护作用。有免疫活性的小鼠反复暴露于注射异种EC - TCPS会诱导强烈的宿主免疫反应。相比之下，预先植入3D - EC会诱导对后续注射EC - TCPS的低反应性，伴有体液反应降低、裂解活性下降以及效应脾细胞频率降低（P < 0.001）。EC与其基质的相互作用决定了其表型、活力和生物分泌潜能。我们现在表明这种微环境相互作用也影响内皮介导的同种异体和异种免疫细胞的激活。3D基质包埋限制了EC启动适应性免疫的能力，并且初次暴露于3D - EC会使对后续暴露于免疫原性EC产生低反应性。这些效应超越了汇合对EC施加的传统控制，甚至可能反映了更高层次的控制。我们的发现可能为内皮介导的疾病和潜在的基于细胞的疗法提供新的见解。
