In a mouse model of Alzheimer’s disease, repeated systemic injections of monophosphoryl lipid A, a LPS-derived Toll-like receptor 4 (TLR4) agonist that exhibits immunomodulatory properties at non-pyrogenic doses induced a potent phagocytic response by microglia, reduced the amyloidβ load in the brain and enhanced cognitive function (Michaud et al., 2013). Here, TLR4 is linked to early-onset autosomal dominant Alzheimer disease.