Dementia with Lewy bodies from the perspective of tauopathy

We immunohistochemically investigated the prevalence and pattern of phosphorylated tau accumulation in neurons and glia in 46 cases of dementia with Lewy bodies (DLB). Tau-positive neurons composed of neurofibrillary tangles (NFT) and pretangle neurons were found in the hippocampal area in all 46 cases, although the ratio of pretangle neurons in tau-positive neurons was higher in the cases showing low NFT stages. Tau-positive astrocytes were found in the periventricular area in 18 of 46 cases, and partly represented argyrophilic thorn-shaped astrocytes. In contrast, tau-positive oligodendroglia were found in the subcortical white matter in 9 of 46 cases, and represented argyrophilic coiled bodies. Tau-positive argyrophilic grains were found in the hippocampal area in the same cases as those with coiled bodies. The 9 cases with tau-positive coiled bodies and grains were included in the 18 cases with tau-positive astrocytes, and showed larger proportions in the low NFT stages than the 46 cases with tau-positive neurons. Tau-positive neurons were positive both to anti-three-repeat (3R) and -4R tau-specific antibodies, while tau-positive astrocytes, coiled bodies and grains were predominantly positive to anti-4R tau-specific antibody. These tau-positive structures were negative to anti-a-synuclein antibody. These findings suggest that the tau accumulation in DLB represents both tau-positive neurons with all six tau isoforms and tau-positive astrocytes, coiled bodies and grains with the 4R tau isoform, and that the different cytoskeletal abnormalities form a link between some neurodegenerative dementing disorders including DLB.