Chimeric antigen receptor macrophages target and resorb amyloid plaques
Alexander B. Kim, Qingli Xiao, Ping Yan, Qiuyun Pan, Gaurav Pandey, Susie Grathwohl, Ernesto Gonzales, Isabella Xu, Yoonho Cho, Hans Haecker, Slava Epelman, Abhinav Diwan, Jin-Moo Lee, Carl J. DeSelm
Alexander B. Kim, Qingli Xiao, Ping Yan, Qiuyun Pan, Gaurav Pandey, Susie Grathwohl, Ernesto Gonzales, Isabella Xu, Yoonho Cho, Hans Haecker, Slava Epelman, Abhinav Diwan, Jin-Moo Lee, Carl J. DeSelm
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Resource and Technical Advance Aging Therapeutics

Chimeric antigen receptor macrophages target and resorb amyloid plaques

Abstract

Substantial evidence suggests a role for immunotherapy in treating Alzheimer’s disease (AD). While the precise pathophysiology of AD is incompletely understood, clinical trials of antibodies targeting aggregated forms of β amyloid (Aβ) have shown that reducing amyloid plaques can mitigate cognitive decline in patients with early-stage AD. Here, we describe what we believe to be a novel approach to target and degrade amyloid plaques by genetically engineering macrophages to express an Aβ-targeting chimeric antigen receptor (CAR-Ms). When injected intrahippocampally, first-generation CAR-Ms have limited persistence and fail to significantly reduce plaque load, which led us to engineer next-generation CAR-Ms that secrete M-CSF and self-maintain without exogenous cytokines. Cytokine secreting “reinforced CAR-Ms” have greater survival in the brain niche and significantly reduce plaque load locally in vivo. These findings support CAR-Ms as a platform to rationally target, resorb, and degrade pathogenic material that accumulates with age, as exemplified by targeting Aβ in AD.

Authors

Alexander B. Kim, Qingli Xiao, Ping Yan, Qiuyun Pan, Gaurav Pandey, Susie Grathwohl, Ernesto Gonzales, Isabella Xu, Yoonho Cho, Hans Haecker, Slava Epelman, Abhinav Diwan, Jin-Moo Lee, Carl J. DeSelm

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Figure 2

Aβ CAR-Ms resorb amyloid plaques of various sizes on brain slices from aged APP/PS1 mice ex vivo and degrade amyloid more efficiently than control macrophages.

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Aβ CAR-Ms resorb amyloid plaques of various sizes on brain slices from a...
(A) Schematic of ex vivo assessment of amyloid plaque phagocytosis. Adjacent brain slices from aged APP/PS1 mice were coincubated with Aβ CAR-M or control CAR-Ms for 44 hours, and plaque load was assessed with HJ3.4 or X-34 immunostaining. (B–E) Assessment of plaque load (B and C), plaque count (D), and plaque fold clearance of Aβ CAR-M over control CAR-Ms (E) on APP/PS1 brain slices after coincubation with no cells, control CAR-M, or Aβ CAR-M with or without GFP-Luciferase. Data shown as mean ± SEM from n = 5–6 independent experiments with 5–6 technical replicates each. Scale bars: 1 mm. Statistical significance was calculated with 1-way ANOVA with Tukey’s multiple-comparison test (C [HJ3.4], D) or unpaired 2-tailed t tests (C [X-34], E). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. In E, “60–90” only contains 4 data points due to a lack of plaques this size in some samples. (F) Representative immunofluorescence microscopy images of individual amyloid-laden control or Aβ CAR-Ms after removal from brain slices from aged APP/PS1 mice for the indicated amount of time and stained with HJ3.4 to visualize intracellular amyloid over time. Scale bars: 2 μm. (G) Quantification of intracellular amyloid in control of Aβ CAR-Ms cultured on brain slices from aged APP/PS1 mice for the indicated amount of time. Data are shown as mean ± SEM from 18 technical replicates. Each condition was fitted to a 1-phase exponential decay function to derive the indicated half-lives.