Beta amyloid aggregates induce sensitised TLR4 signalling causing long-term potentiation deficit and rat neuronal cell death

The molecular events causing memory loss and neuronal cell death in Alzheimer's disease (AD) over time are still unknown. Here we found that picomolar concentrations of soluble oligomers of synthetic beta amyloid (A beta 42) aggregates incubated with BV2 cells or rat astrocytes caused a sensitised response of Toll-like receptor 4 (TLR4) with time, leading to increased production of TNF-alpha. A beta aggregates caused long term potentiation (LTP) deficit in hippocampal slices and predominantly neuronal cell death in co-cultures of astrocytes and neurons, which was blocked by TLR4 antagonists. Soluble A beta aggregates cause LTP deficit and neuronal death via an autocrine/paracrine mechanism due to TLR4 signalling. These findings suggest that the TLR4-mediated inflammatory response may be a key pathophysiological process in AD. Hughes et al. investigate the TLR4-mediated inflammatory response in Alzheimer's disease and show that picomolar concentrations of soluble amyloid beta aggregates lead to a sensitised response of TLR4 with time, resulting in increased TNF-alpha production. They suggest the use of near physiological concentration of soluble aggregates can cause long-term potentiation deficit and neuronal death through an autocrine/paracrine mechanism due to TLR4 signalling.