Glutamine Antagonist JHU-083 Normalizes Aberrant Hippocampal Glutaminase Activity and Improves Cognition in APOE4 Mice

Article type: Research Article

Authors: Hollinger, Kristen R.^{a; b; c} | Zhu, Xiaolei^{a; c} | Khoury, Elizabeth S.^d | Thomas, Ajit G.^c | Liaw, Kevin^e | Tallon, Carolyn^{b; c} | Wu, Ying^c | Prchalova, Eva^{b; c} | Kamiya, Atsushi^a | Rojas, Camilo^{b; c} | Kannan, Sujatha^d | Slusher, Barbara S.^{a; b; c; f; g; h; i; *}

Affiliations: [a] Departments of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD, USA | [b] Departments of Neurology, Johns Hopkins University, Baltimore, MD, USA | [c] Departments of Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD, USA | [d] Departments of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, USA | [e] Departments of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA | [f] Departments of Pharmacology and Molecular Sciences, Johns Hopkins University, Baltimore, MD, USA | [g] Departments of Neuroscience, Johns Hopkins University, Baltimore, MD, USA | [h] Departments of Medicine, Johns Hopkins University, Baltimore, MD, USA | [i] Departments of Oncology, and Johns Hopkins University, Baltimore, MD, USA

Correspondence: [*] Correspondence to: Barbara S. Slusher, PhD, MAS, Rangos Suite 277, 855 N. Wolfe Street, Baltimore, MD 21205, USA. Tel.: +1 410 614 0662; E-mail: bslusher@jhmi.edu.

Abstract: Background:Given the emergent aging population, the identification of effective treatments for Alzheimer’s disease (AD) is critical. Objective:We investigated the therapeutic efficacy of JHU-083, a brain-penetrable glutamine antagonist, in treating AD using the humanized APOE4 knock-in mouse model. Methods:Cell culture studies were performed using BV2 cells and primary microglia isolated from hippocampi of adult APOE4 knock-in mice to evaluate the effect of JHU-083 treatment on LPS-induced glutaminase (GLS) activity and inflammatory markers. Six-month-old APOE4 knock-in mice were administered JHU-083 or vehicle via oral gavage 3x/week for 4–5 months and cognitive performance was assessed using the Barnes maze. Target engagement in the brain was confirmed using a radiolabeled GLS enzymatic activity assay, and electrophysiology, gastrointestinal histology, blood chemistry, and CBC analyses were conducted to evaluate the tolerability of JHU-083. Results:JHU-083 inhibited the LPS-mediated increases in GLS activity, nitic oxide release, and pro-inflammatory cytokine production in cultured BV2 cells and primary microglia isolated from APOE4 knock-in AD mice. Chronic treatment with JHU-083 in APOE4 mice improved hippocampal-dependent Barnes maze performance. Consistent with the cell culture findings,postmortem analyses of APOE4 mice showed increased GLS activity in hippocampal CD11b+ enriched cells versus age-matched controls, which was completely normalized by JHU-083 treatment. JHU-083 was well-tolerated, showing no weight loss effect or overt behavioral changes. Peripheral nerve function, gastrointestinal histopathology, and CBC/clinical chemistry parameters were all unaffected by chronic JHU-083 treatment. Conclusion:These results suggest that the attenuation of upregulated hippocampal glutaminase by JHU-083 represents a new therapeutic strategy for AD.

Keywords: Alzheimer’s disease, APOE, glutamate, glutaminase, microglia

DOI: 10.3233/JAD-190588

Journal: Journal of Alzheimer's Disease, vol. 77, no. 1, pp. 437-447, 2020