阿尔茨海默病神经细胞凋亡与小胶质细胞活化的关系

目的　探讨阿尔茨海默病 (Alzheimer′sdisease ,AD)神经细胞凋亡与小胶质细胞活化的关系及活化的小胶质细胞在AD老年斑形成和进展中的作用。方法　收集 10例AD尸检材料及 4例非神经系统疾病死亡的老年尸检材料作为对照 ,进行白细胞介素 1α(IL 1α)免疫组织化学和原位DNA末端转移酶技术 (TUNEL)双重标记及淀粉样 β蛋白免疫组织化学和TUNEL双重标记。 结果　AD组静止的小胶质细胞数与对照组差异无显著性 (P >0 0 5 ) ,但活化的小胶质细胞数明显比对照组高 (P <0 0 1)。活化的小胶质细胞增大、变形 ,可进一步分为初级活化的小胶质细胞、增大的小胶质细胞及巨噬细胞 3种亚型。上述 3种活化的小胶质细胞数分别为 (5 4 0± 0 87)、(11 5 0± 1 2 5 )、(3 4 0± 0 32 )个 /mm2 ,占所有活化的小胶质细胞的比例分别为 2 6 6 0 % ,5 6 6 5 % ,16 75 %。AD组TUNEL阳性的凋亡的神经细胞数明显比对照组高 (P <0 0 5 ) ,且凋亡的神经细胞与活化的小胶质细胞之间具有相关性 (P <0 0 1)。活化的小胶质细胞在 4种类型老年斑中的分布比例不同 ,许多初级活化的小胶质细胞 (4 2 3% ) ,大多数增大的小胶质细胞和巨噬细胞 (分别是 5 6 2 %、70 6 % )分布在弥漫性神经突斑中。结论　小胶质细胞增生、活化在AD中

Relationship between apoptosis of neurons and microglia activation in Alzheimer's disease

OBJECTIVE: To assess the relationship between microglia activation and apoptosis of neurons, and the significance of activated microglias in the formation and progression of senile plaques in Alzheimer's disease. METHODS: IL-1alpha and beta-amyloid immunohistochemistry, combined with TUNEL assay were used to assess brain tissue samples from 10 patients with Alzheimer's disease and 4 negative control cases without neurological disease. RESULTS: The number of resting microglias in the brains of Alzheimer's disease patients was similar to that of the control group (P > 0.05), but the number of activated microglias was significant greater in the Alzheimer's disease patients than that of the controls (P < 0.01). The activated microglias displayed altered size and morphology, and was therefore, categorized into three subtypes as primed, enlarged and phagocytic microglias. The numbers of primed, enlarged and phagocytic microglias were 5.4 +/- 0.87, 11.5 +/- 1.25, and 3.4 +/- 0.32 microglia/mm2 and represented 26.6%, 56.65%, and 16.75% of all activated microglias respectively. The number of TUNEL positive apoptotic neurons was significantly greater in Alzheimer patients than that in the control group (P < 0.05). There was a close relationship between the apoptosis of neurons and the activation of microglias (P < 0.01). The activated microglias were differentially distributed among four different plaque types in Alzheimer patients. Many primed (42.3%) and most of the enlarged and phagocytic microglias (56.2% and 70.6%) were present in the diffuse neuritic plaques. CONCLUSIONS: Hyperplasia and activation of microglias are a common phenomena in AD and may play an important role in its pathogenesis. There is a close relationship between the apoptosis of neurons and activation of microglias. The activation of microglias may play a key pathogenic role in senile plaque formation and progression of Alzheimer disease.