Lymph Node Immune Pathway Drives Tau-Related Brain Damage — SkimNews
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- WashU Medicine researchers identified an immune pathway originating in lymph nodes where dendritic cells prime CD8 T cells before they travel into the brain and contribute to tau-related neurodegeneration.
- David M. Holtzman's team found that eliminating dendritic cells from lymph nodes in mice caused elevated brain CD8 T cells and associated brain damage to largely disappear, while the mice retained cognitive abilities.
- Tau tangle levels in the brain did not change after the immune pathway was blocked, indicating that the cognitive protection came from suppressing T cell activity rather than clearing tau itself.
- Holtzman, senior author and a WashU neurology professor, said the finding suggests Alzheimer's treatments may not need to cross the blood-brain barrier since the disease-driving signals originate in more accessible peripheral tissue.
- The study, published Sept. 3 in Nature Neuroscience with Hao Hu, PhD as first author and Jason Ulrich, PhD as co-senior author, extends earlier work from Holtzman's lab showing that removing T cells from the brain prevented neurodegeneration in tauopathy mouse models.
- The researchers are now testing whether interfering with dendritic cell activity in midlife — around when tau tangles begin to emerge — reproduces the protection seen when the cells were blocked from birth.
Why it matters: If the peripheral priming mechanism holds in humans, it would give drug developers a Alzheimer's treatment target that lives outside the blood-brain barrier, opening up a wider range of immune-modulating drugs already approved for other diseases. The finding that cognition was rescued even though tau tangles persisted reframes the damage: it implicates the immune attack on tau-burdened neurons, not tau accumulation alone, as the driver of cognitive decline in these models.
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