Microglia are often found near damaged tissue in Alzheimer's disease patients, but whether the brain's innate immune cells are helpful or harmful in the disease has been an open question. Now, German researchers have evidence that both camps got it right. A pair of studies reveals that microglia play opposing roles in AD pathogenesis: they not only eliminate β-amyloid aggregates via phagocytosis but also kill nearby neurons by causing inflammation and the release of neurotoxic proteases.

Importantly, the reports suggest that the two functions of microglia are controlled by different cell-surface receptors, thus providing a road map for how to clear β-amyloid (Aβ) plaques without destroying healthy neurons that are in close proximity. A full report is available here