Deficiency of microvascular thrombomodulin and up-regulation of protease-activated receptor-1 in irradiated rat intestine: possible link between endothelial dysfunction and chronic radiation fibrosis.
Deficiency of microvascular thrombomodulin and up-regulation of protease-activated receptor-1 in irradiated rat intestine: possible link between endothelial dysfunction and chronic radiation fibrosis.
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DOI：
10.1016/s0002-9440(10)61156-x
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发表时间：
2002-06
期刊：
影响因子：
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通讯作者：
Junru Wang;Huaien Zheng;Xuemei Ou;L. Fink;M. Hauer-Jensen
中科院分区：
文献类型：
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作者：
Junru Wang;Huaien Zheng;Xuemei Ou;L. Fink;M. Hauer-Jensen
微血管损伤被认为是放射性纤维化的机制之一，但体内内皮细胞功能障碍与放射性纤维化之间的直接分子联系尚未建立。我们检测了辐射诱导的照射后肠道内皮细胞血栓调节蛋白(TM)和蛋白酶激活受体-1(PAR-1)的变化，以及它们与辐射损伤的结构、细胞和分子方面的关系。大鼠小肠局部接受分次X射线照射。在最后一次放射治疗后24小时、2周、6周和26周，使用定量组织学和形态计量学对结构损伤进行评估。免疫组织化学定量检测TM、中性粒细胞、转化生长因子-β、I型和III型胶原。免疫组织化学定位PAR-1蛋白，原位杂交鉴定表达TM或PAR-1转录本的细胞。采用激光捕获显微切割技术和竞争性逆转录聚合酶链式反应技术检测大鼠肠平滑肌稳态PAR-1mRNA水平。辐射引起微血管TM持续的、剂量依赖性的下降。TM阳性血管的数量与放射性肠病的所有参数相关，在统计模型中调整了辐射剂量和观察时间后，仍与中性粒细胞浸润、肠壁增厚和I型胶原沉积独立相关。PAR-1在照射后的小肠血管和肠平滑肌细胞中的表达和免疫反应增强。照射后的肠平滑肌PAR-1mRNA表达增加一倍。肠道照射上调PAR-1，并导致剂量依赖的、持续的微血管TM缺陷，这与辐射毒性的严重程度独立相关。在临床放射治疗中，应探索旨在保护或恢复内皮细胞TM或阻断PAR-1的干预措施，以此作为提高治疗率的策略。
Microvascular injury is believed to be mechanistically involved in radiation fibrosis, but direct molecular links between endothelial dysfunction and radiation fibrosis have not been established in vivo. We examined radiation-induced changes in endothelial thrombomodulin (TM) and protease-activated receptor-1 (PAR-1) in irradiated intestine, and their relationship to structural, cellular, and molecular aspects of radiation injury. Rat small intestine was locally exposed to fractionated X-radiation. Structural injury was assessed 24 hours and 2, 6, and 26 weeks after the last radiation fraction using quantitative histology and morphometry. TM, neutrophils, transforming growth factor-β, and collagens I and III were assessed by quantitative immunohistochemistry. PAR-1 protein was localized immunohistochemically, and cells expressing TM or PAR-1 transcript were identified by in situ hybridization. Steady-state PAR-1 mRNA levels in intestinal smooth muscle were determined using laser capture microdissection and competitive reverse transcriptase-polymerase chain reaction. Radiation caused a sustained, dose-dependent decrease in microvascular TM. The number of TM-positive vessels correlated with all parameters of radiation enteropathy and, after adjusting for radiation dose and observation time in a statistical model, remained independently associated with neutrophil infiltration, intestinal wall thickening, and collagen I accumulation. PAR-1 immunoreactivity and transcript increased in vascular and intestinal smooth muscle cells in irradiated intestine. PAR-1 mRNA increased twofold in irradiated intestinal smooth muscle. Intestinal irradiation up-regulates PAR-1 and causes a dose-dependent, sustained deficiency of microvascular TM that is independently associated with the severity of radiation toxicity. Interventions aimed at preserving or restoring endothelial TM or blocking PAR-1 should be explored as strategies to increase the therapeutic ratio in clinical radiation therapy.