Aβ oligomers trigger necroptosis-mediated neurodegeneration via microglia activation in Alzheimer's disease.

Abstract

Alzheimers disease (AD) is a major adult-onset neurodegenerative condition with no available treatment. Compelling reports point amyloid-{beta} (A{beta}) as the main etiologic agent that triggers AD. Although there is extensive evidence of detrimental crosstalk between A{beta} and microglia that contributes to neuroinflammation in AD, the exact mechanism leading to neuron death remains unknown. Using postmortem human AD brain tissue, we show that A{beta} pathology is associated with the necroptosis effector pMLKL. Moreover, we found that the burden of A{beta}o correlates with the expression of key markers of necroptosis activation. Additionally, inhibition of necroptosis by pharmacological or genetic means, reduce neurodegeneration and memory impairment triggered by A{beta}o in mice. Since microglial activation is emerging as a central driver for AD pathogenesis, we then tested the contribution of microglia to the mechanism of A{beta}o-mediated necroptosis activation in neurons. Using an in vitro model, we show that conditioned medium from A{beta}o-stimulated microglia elicited necroptosis in neurons through activation of TNF- signaling, triggering extensive neurodegeneration. Notably, necroptosis inhibition provided significant neuronal protection. Together, these findings suggest that A{beta}o-mediated microglia stimulation in AD contributes to necroptosis activation in neurons and neurodegeneration. As necroptosis is a druggable degenerative mechanism, our findings might have important therapeutic implications to prevent the progression of AD.