Oxidative stress and aging : significance of Metallothionein in the respiratory organs of dogs

可吸入悬浮颗粒物(SPM)对人体健康的影响受到世界各国的高度关注。SPM通过空气从一个大陆转移到另一个大陆(跨界空气污染)。在SPM之外，通过鼻孔吸入的超细颗粒很容易被输送到肺部的肺泡，在那里可能会发生包括炎症在内的各种变化。SPM的含量和累积的SPM所引起的病理变化，以及网状金属硫蛋白作为保护系统对抗SPM诱导的氧化应激的意义尚不清楚。在本研究中，我们报道了1)肺和肺门淋巴结的形态变化和2)金属含量，用层粘连蛋白免疫组织化学和银染分析基底膜，用普鲁士蓝DAB和后DAB增强技术检测铁和肝纤维化，作为组织学检查。用湿法消化…后用[CP-MS]测定金属更多的组织样本。取7只1周~4岁的幼年动物和30只10~17岁的老年动物的肺和肺门淋巴结。SPM的大小似乎在超细颗粒范围内(小于100 nm)，主要分布在组织中的巨噬细胞中。老年犬肺泡壁可见金属硫蛋白免疫反应阳性、纤维化及基底膜变薄。肺组织和肺门淋巴结中SPM沉积强度随年龄增长而增加。8-OHdG免疫组织化学显示释放的活性氧对组织有损伤迹象。金属(Fe、Al)含量随年龄增长而升高，其变化规律与环境空气相似。这些结果表明，犬的呼吸器官可能是研究SPM对呼吸系统的影响以及包括金属硫蛋白在内的内在蛋白保护机制的良好生物样品。较少

Effects of inhaled suspended particulate matters (SPM) on the human health are great concern in the world. SPM are transferred from the one continent to the other through the air (trans boundary air pollution). Out of SPM, ultra fine particles inhaled through the nostril are easily transported to the alveoli in the lung, where a variety of changes including inflammation may occur. Contents of SPM and pathological changes induced by the accumulated SPM, significance of netallothionein as a protection system against the oxidative stress induced by the SPM are yet to be elucidated. In this study, we report 1)morphological changes and 2)metal contents in the lung and hilar lymph nodes from dogs.Laminin immunohistochemistry and silver staining for the analysis of basement membrane, Prussian blue DAB and post DAB enhancement technique for the detection of iron and azan stain for the fibrosis were carried out as histological examination. Metals were determined using [CP-MS after wet digestion … More of the tissue samples. Lung and hilar lymph nodes from 7 young animals, ranging in age from 1 week to 4 years, and from 30 old animals, from 10 to 17 years, were used. Size of SPM, most of which were observed in the macrophages in the tissues, appeared to be within the range of ultra fine particles (less than 100nm). Metallothionein immunoreactivity, Fibrosis and attenuated basement membrane were demonstrated in the alveolar walls of aged dog lungs. Intensity of SPM deposition in both lung tissue and hilar lymph nodes increased with age. Signs of tissue damage by the released reactive oxygen species were also shown with the use of 8-OHdG immunohistochemistry. Age-related increase of the level of metals(Fe, Al) was demonstrated ; the pattern of the metal contents was similar to that of ambient air. These findings suggest that respiratory organs from dogs may be good biological samples for the study of the effect of SPM on the respiratory system and protection mechanism by intrinsic proteins including metallothionein. Less