SCIEN C E A D V A N C E S

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R E S E A R C H A R T ICLE

HEALTH AND MEDICINE

Porphyromonas gingivalis in Alzheimer’s disease brains: Evidence for disease causation and treatment with small-molecule inhibitors

Stephen S. Dominy 1 * † , Casey Lynch 1 *, Florian Ermini 1 , Malgorzata Benedyk 2,3 , Agata Marczyk 2 , Andrei Konradi 1 , Mai Nguyen 1 , Ursula Haditsch 1 , Debasish Raha 1 , Christina Griffin 1 , Leslie J. Holsinger 1 , Shirin Arastu-Kapur 1 , Samer Kaba 1 , Alexander Lee 1 , Mark I. Ryder 4 , Barbara Potempa 5 , Piotr Mydel 2,6 , Annelie Hellvard 3,6 , Karina Adamowicz 2 , Hatice Hasturk 7,8 , Glenn D. Walker 9 , Eric C. Reynolds 9 , Richard L. M. Faull 10 , Maurice A. Curtis 11,12 , Mike Dragunow 11,13 , Jan Potempa 2,5 *

Porphyromonas gingivalis, the keystone pathogen in chronic periodontitis, was identified in the brain of Alzheimer’s disease patients. Toxic proteases from the bacterium called gingipains were also identified in the brain of Alzheimer’s patients, and levels correlated with tau and ubiquitin pathology. Oral P. gingivalis infection in mice resulted in brain colonization and increased production of A 1–42 , a component of amyloid plaques. Further, gingipains were neurotoxic in vivo and in vitro, exerting detrimental effects on tau, a protein needed for normal neuronal function. To block this neurotoxicity, we designed and synthesized small-molecule inhibitors targeting gingipains. Gingipain inhibition reduced the bacterial load of an established P. gingivalis brain infection, blocked A 1–42 production, reduced neuroinflammation, and rescued neurons in the hippocampus. These data suggest that gingipain inhibitors could be valuable for treating P. gingivalis brain colonization and neurodegeneration in Alzheimer’s disease.