Tracing TMEM106B fibril deposition in aging and Parkinson's disease with dementia brains.

Transmembrane protein 106B (TMEM106B), previously identified as a risk factor in frontotemporal lobar degeneration, has recently been detected to form fibrillar aggregates in the brains of patients with various neurodegenerative diseases (NDs) and normal elders. While the specifics of when and where TMEM106B fibrils accumulate in human brains, as well as their connection to aging and disease progression, remain poorly understood. Here, we identified an antibody (NBP1-91311) that directly binds to TMEM106B fibrils extracted from the brain in vitro and to Thioflavin S-positive TMEM106B fibrillar aggregates in brain sections. We discovered that TMEM106B fibrils deposit in the human brain in an age-dependent manner. Notably, the TMEM106B fibril load in the brains of Parkinson's disease with dementia patients was significantly higher than in age-matched elders. Additionally, we found that TMEM106B fibrils predominantly accumulate in astrocytes and neurons and do not co-localize with the pathological deposition formed by other amyloid proteins such as α-synuclein, Aβ, and Tau. Our work provides a comprehensive analysis of the burden and cellular distribution of TMEM106B fibrils in human brains, underscoring the impact of both aging and disease conditions on TMEM106B fibril deposition. This highlights the potential significance of TMEM106B fibrils in various age-related NDs.