TNFR2 contributes to synaptic potentiation failure in hippocampal synapses and memory loss in a familial Alzheimer's disease mouse model.

Alzheimer's disease (AD) is a critical health problem with a projected increase in prevalence, demanding more efforts to find an effective treatment. AD is characterized by amyloid-β (Aβ) accumulation, which drives neuroinflammation. Aβ-mediated Caspase-1-dependent neuroinflammation fuels memory loss through pro-inflammatory cytokines signaling. For instance, TNF promotes synaptic plasticity dysfunction impairing long-term potentiation (LTP), an early hallmark of AD. Thus, targeting TNF receptors (TNFR1 and TNFR2) with antagonists/agonists is a promising therapeutic strategy. Here, we found that intrahippocampal administration of a TNFR2-specific blocking antibody improved recognition memory, spatial memory, and synaptic potentiation in response to chemically induced LTP (cLTP) in 5xFAD mice. Additionally, we found that TNFR2 predominates over TNFR1 on the surface of hippocampal synaptosomes from wild-type mice and that TNFR2 levels increased on the synaptosomal surface of 5xFAD mice in a Caspase-1-dependent manner. Notably, Caspase-1 deletion and TNFR2 blocking improved synaptic potentiation of hippocampal synaptosomes from 5xFAD mice in response to cLTP. TNF signaling via TNFR2 also reduced cell viability and impaired BDNF-mediated neurite outgrowth in SN56 cholinergic cells. Thus, our data reveal that TNFR2 contributes to neuron- and synapse-specific deleterious effects, impacting the memory of 5xFAD mice, suggesting that TNFR2-dependent signaling at the synapsis should be considered for AD treatment.