Microglial Kv1.3 Channels as a Potential Target for Alzheimer's Disease

Microglia, the major inflammatory cells of the brain, play a pivotal role in the initiation and progression of Alzheimer's Disease (AD) by either phagozytosing amyloid‐β deposits or by releasing cytotoxic and pro‐inflammatory substances in response to activation by amyloid‐β aggregates, including amyloid‐β oligomers (AβO). We here propose microglial Kv1.3 channels as a novel target for curbing the harmful effects of Aβ‐induced microglia activation. Microglia isolated from the brains of adult 5xFAD mice expressed higher levels of Kv1.3 than microglia from age‐matched control mice. We further observed strong Kv1.3 immunoreactivities in microglia associated with amyloid plaques in brains of 5xFAD mice. Proof for the functional importance of Kv1.3 in microglia comes from our observations that the Kv1.3 blocker PAP‐1 inhibits AβO‐stimulated NO production as well as microglia‐mediated neurotoxicity in dissociated cultures and organotypic brain slices. A 6‐week course of daily PAP‐1 injections also reduced the degree of microglia activation in 5xFAD mice. In contrast, Kv1.3 blockade with PAP‐1 does not affect phagocytosis of Aβ aggregates by microglia. These observations suggest that Kv1.3 blockers might preferentially inhibit microglia mediated neuronal killing without affecting beneficial functions such as scavenging of debris. Supported by NIH and Alzheimer's Association