Glutaminyl cyclase inhibition attenuates pyroglutamate Aβ and Alzheimer’s disease–like pathology

Because of their abundance, resistance to proteolysis, rapid aggregation and neurotoxicity, N-terminally truncated and, in particular, pyroglutamate (pE)-modified Aβ peptides have been suggested as being important in the initiation of pathological cascades resulting in the development of Alzheimer’s disease. This study found that the N-terminal pE-formation is catalyzed by glutaminyl cyclase in vivo. Glutaminyl cyclase expression was upregulated in the cortices of individuals with Alzheimer’s disease and correlated with the appearance of pE-modified Aβ. Oral application of a glutaminyl cyclase inhibitor resulted in reduced Aβ3(pE)–42 burden in two different transgenic mouse models of Alzheimer’s disease and in a new Drosophila model. Treatment of mice was accompanied by reductions in Aβx–40/42, diminished plaque formation and gliosis and improved performance in context memory and spatial learning tests. These observations are consistent with the hypothesis that Aβ3(pE)–42 acts as a seed for Aβ aggregation by self-aggregation and co-aggregation with Aβ1–40/42. Therefore, Aβ3(pE)–40/42 peptides seem to represent Aβ forms with exceptional potency for disturbing neuronal function. The reduction of brain pE-Aβ by inhibition of glutaminyl cyclase offers a new therapeutic option for the treatment of Alzheimer’s disease and provides implications for other amyloidoses, such as familial Danish dementia.