Type 2 cannabinoid receptor expression on microglial cells regulates neuroinflammation during graft-versus-host disease
Alison Moe, Aditya Rayasam, Garrett Sauber, Ravi K. Shah, Ashley Doherty, Cheng-Yin Yuan, Aniko Szabo, Bob M. Moore II, Marco Colonna, Weiguo Cui, Julian Romero, Anthony E. Zamora, Cecilia J. Hillard, William R. Drobyski
Alison Moe, Aditya Rayasam, Garrett Sauber, Ravi K. Shah, Ashley Doherty, Cheng-Yin Yuan, Aniko Szabo, Bob M. Moore II, Marco Colonna, Weiguo Cui, Julian Romero, Anthony E. Zamora, Cecilia J. Hillard, William R. Drobyski
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Research Article Neuroscience

Type 2 cannabinoid receptor expression on microglial cells regulates neuroinflammation during graft-versus-host disease

Abstract

Neuroinflammation is a recognized complication of immunotherapeutic approaches such as immune checkpoint inhibitor treatment, chimeric antigen receptor therapy, and graft versus host disease (GVHD) occurring after allogeneic hematopoietic stem cell transplantation. While T cells and inflammatory cytokines play a role in this process, the precise interplay between the adaptive and innate arms of the immune system that propagates inflammation in the central nervous system remains incompletely understood. Using a murine model of GVHD, we demonstrate that type 2 cannabinoid receptor (CB2R) signaling plays a critical role in the pathophysiology of neuroinflammation. In these studies, we identify that CB2R expression on microglial cells induces an activated inflammatory phenotype that potentiates the accumulation of donor-derived proinflammatory T cells, regulates chemokine gene regulatory networks, and promotes neuronal cell death. Pharmacological targeting of this receptor with a brain penetrant CB2R inverse agonist/antagonist selectively reduces neuroinflammation without deleteriously affecting systemic GVHD severity. Thus, these findings delineate a therapeutically targetable neuroinflammatory pathway and have implications for the attenuation of neurotoxicity after GVHD and potentially other T cell–based immunotherapeutic approaches.

Authors

Alison Moe, Aditya Rayasam, Garrett Sauber, Ravi K. Shah, Ashley Doherty, Cheng-Yin Yuan, Aniko Szabo, Bob M. Moore II, Marco Colonna, Weiguo Cui, Julian Romero, Anthony E. Zamora, Cecilia J. Hillard, William R. Drobyski

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Figure 5

Pharmacological administration of a brain-penetrant CB2R inverse agonist/antagonist reduces inflammation in the CNS during GVHD.

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Pharmacological administration of a brain-penetrant CB2R inverse agonist...
(A) Chemical structure of SMM-189. (B and C) Serum level (B) and brain concentration (C) of SMM-189 in naïve and Balb/c mice transplanted with B6 BM or B6 BM and spleen cells. (D) Ratio of brain to serum SR144528 and SMM-189 concentrations. Results in B–D are from 2 experiments (n = 5–10 mice/group). (E) 2-AG levels in the amygdala, brainstem, cerebellum, and prefrontal cortex 14 days after transplantation. Results are from 3 experiments (n = 14–15 mice/group). (F–N) Balb/c recipients were transplanted with B6 BM alone or B6 BM and spleen cells. Animals were then treated with SMM-189 or vehicle control. (F) The percentage and absolute number of donor CD4+ and CD8+ T cells in the brains of mice 14 days after transplantation. (G–J) The absolute number of CD4+ and CD8+ T cells that produced IFN-γ, TNF-α, IL-6, or GM-CSF. (K) Absolute number of microglial cells. (L and M) Absolute number of MHC class II, CD80, and CD86 expressing microglial cells. Results in panels F–M are from 2 experiments (n = 6–10 mice/group). (N) Representative Western blot images and scatterplots depicting normalized expression of cleaved caspase 3 in the brain from mice treated with either SMM-189 or a vehicle control. Vertical lines on Western blots denote noncontiguous gel lanes. Data are from 2 experiments (n = 4–10 mice/group). (O–Q) Balb/c recipients were transplanted with B6 BM alone (n = 6) or with B6 spleen cells (n = 10) and treated with SMM-189 or vehicle. Overall survival (O), serial weight curves (P), and clinical score (Q) are shown. Results are from 2 experiments (n = 6–10 mice/group). In panels P and Q, BM alone mice only received vehicle. Data are presented as mean ± SD. Statistics were performed using a 1-way ANOVA with Tukey’s test for multiple group comparisons. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Source data are provided as a Supporting Data Values file.