Tsuji Daisuke, Kuroki Aya, Ishibashi Yasuhiro, Itakura Tomohiro, Kuwahara Jun, Yamanaka Shoji, Itoh Kohji
Department of Medicinal Biotechnology, Institute of Medicinal Resources, Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78 Sho-machi, Tokushima 770-8505, Japan.
J Neurochem. 2005 Mar;92(6):1497-507. doi: 10.1111/j.1471-4159.2005.02986.x.
Sandhoff disease is a lysosomal storage disease caused by simultaneous deficiencies of beta-hexosaminidase A (HexA; alphabeta) and B (HexB; betabeta), due to a primary defect of the beta-subunit gene (HEXB) associated with excessive accumulation of GM2 ganglioside (GM2) and oligosaccharides with N-acetylhexosamine residues at their non-reducing termini, and with neurosomatic manifestations. To elucidate the neuroinflammatory mechanisms involved in its pathogenesis, we analyzed the expression of chemokines in Sandhoff disease model mice (SD mice) produced by disruption of the murine Hex beta-subunit gene allele (Hexb-/-). We demonstrated that chemokine macrophage inflammatory protein-1 alpha (MIP-1alpha) was induced in brain regions, including the cerebral cortex, brain stem and cerebellum, of SD mice from an early stage of the pathogenesis but not in other systemic organs. On the other hand, little changes in other chemokine mRNAs, including those of RANTES (regulated upon activation, normal T expressed and secreted), MCP-1 (monocyte chemotactic protein-1), SLC (secondary lymphoid-tissue chemokine), fractalkine and SDF-1 (stromal derived factor-1), were detected. Significant up-regulation of MIP-1alpha mRNA and protein in the above-mentioned brain regions was observed in parallel with the accumulation of natural substrates of HexA and HexB. Immunohistochemical analysis revealed that MIP-1alpha-immunoreactivity (IR) in the above-mentioned brain regions of SD mice was co-localized in Iba1-IR-positive microglial cells and partly in glial fibrillary acidic protein (GFAP)-IR-positive astrocytes, in which marked accumulation of N-acetylglucosaminyl (GlcNAc)-oligosaccharides was observed from the presymptomatic stage of the disease. In contrast, little MIP-1alpha-IR was observed in neurons in which GM2 accumulated predominantly. These results suggest that specific induction of MIP-1alpha might coincide with the accumulation of GlcNAc-oligosaccharides due to a HexB deficiency in resident microglia and astrocytes in the brains of SD mice causing their activation and acceleration of the progressive neurodegeneration in SD mice.
桑德霍夫病是一种溶酶体贮积病，由β-己糖胺酶A（HexA；αβ）和B（HexB；ββ）同时缺乏引起，这是由于β亚基基因（HEXB）的原发性缺陷，导致GM2神经节苷脂（GM2）和在其非还原末端带有N-乙酰己糖胺残基的寡糖过度积累，并伴有神经躯体表现。为了阐明其发病机制中涉及的神经炎症机制，我们分析了通过破坏小鼠Hexβ亚基基因等位基因（Hexb-/-）产生的桑德霍夫病模型小鼠（SD小鼠）中趋化因子的表达。我们证明，趋化因子巨噬细胞炎性蛋白-1α（MIP-1α）在SD小鼠发病早期就在包括大脑皮层、脑干和小脑在内的脑区中被诱导，但在其他全身器官中未被诱导。另一方面，未检测到其他趋化因子mRNA的显著变化，包括受激活调节正常T细胞表达和分泌的趋化因子（RANTES）、单核细胞趋化蛋白-1（MCP-1）、二级淋巴组织趋化因子（SLC）、 fractalkine和基质衍生因子-1（SDF-1）。在上述脑区中观察到MIP-1α mRNA和蛋白的显著上调，同时伴有HexA和HexB天然底物的积累。免疫组织化学分析显示，SD小鼠上述脑区中的MIP-1α免疫反应性（IR）与离子钙结合衔接分子1（Iba1）-IR阳性小胶质细胞共定位，部分与胶质纤维酸性蛋白（GFAP）-IR阳性星形胶质细胞共定位，在疾病的症状前期阶段，在这些细胞中观察到N-乙酰葡糖胺（GlcNAc）-寡糖的显著积累。相比之下，在主要积累GM2的神经元中几乎未观察到MIP-1α-IR。这些结果表明，MIP-1α的特异性诱导可能与SD小鼠脑中驻留的小胶质细胞和星形胶质细胞中由于HexB缺乏导致的GlcNAc-寡糖积累同时发生，从而导致它们的激活并加速SD小鼠进行性神经变性。
