TDP-43 is a protein only relatively recently discovered to undergo pathological modification and aggregation in the aging brain. Much like amyloid-β, α-synuclein, and tau, this aggregation is thought important in the progression of specific neurodegenerative conditions. Here, researchers present evidence for TDP-43 aggregation to contribute to lost function in vascular dementia. Vascular dementia arises from a reduced blood supply to the brain, or other issues in the vasculature supplying brain tissue with the oxygen and nutrients it needs. The brain operates at the edge of metabolic capacity at the best of times, and as that supply diminishes with age, function suffers. Can some of the consequent damage done to the brain be prevented? Obviously it would be ideal to maintain a healthy vasculature instead of trying to compensate for vascular aging, but the research community does spend a lot of time looking at possible compensatory approaches, ways to sabotage at least some of the maladaptive reactions to the damage and dysfunction of aging.
Vascular dementia (VaD) ranks as the second most common cause of dementia worldwide and is linked to the highest mortality rate among dementia subtypes. A key driver of VaD pathogenesis is chronic cerebral hypoperfusion (CCH), a state of persistently reduced blood flow to the brain stemming from cerebrovascular compromise. A hallmark of VaD, CCH can diminish cerebral blood flow by as much as 40%, triggering hypoxia-induced cellular stress. This includes oxidative damage, mitochondrial failure, and heightened neuroinflammation, which collectively impair blood-brain barrier integrity and promote white matter lesion (WML) formation.
Recent evidence points to Tar DNA-binding protein 43 (TDP-43) as a potential mediator in this cascade. While TDP-43′s pathological role is well-established in amyotrophic lateral sclerosis (ALS), frontotemporal dementia, and Alzheimer's disease (AD), its involvement in VaD is poorly understood. In healthy neurons, TDP-43 is crucial for synaptic function and stress response. Under pathological conditions, however, it undergoes detrimental modifications, including hyperphosphorylation, nuclear-to-cytoplasmic mislocalization, and aggregation that are common processes across neurodegenerative diseases. These aberrant forms of TDP-43 lose their normal function and can acquire toxic properties, potentially exacerbating neuroinflammation. While TDP-43 pathology is a well-established feature of several neurodegenerative diseases, its potential role in the context of cerebrovascular injury remains largely unexplored.
This study demonstrates that CCH, a key feature of VaD, triggers pathological TDP-43 changes, namely cytoplasmic mislocalisation and hyperphosphorylation, in both in vivo and in vitro models. In a mouse model of VaD, time-dependent cytoplasmic accumulation of TDP-43 and pTDP-43 was observed in cortical and hippocampal neurons, with elevated pTDP-43 despite stable total TDP-43 levels, implicating phosphorylation in its aberrant redistribution. These results mirror hallmark features of TDP-43 proteinopathies in neurodegenerative diseases, such as ALS and AD, and suggest that similar mechanisms may be triggered by vascular insults.
Link: https://doi.org/10.1002/alz.71196
View the full article at FightAging
