Type 2 cannabinoid receptor expression on microglial cells regulates neuroinflammation during graft-versus-host disease
Alison Moe, … , Cecilia J. Hillard, William R. Drobyski
Alison Moe, … , Cecilia J. Hillard, William R. Drobyski
Published April 25, 2024
Citation Information: J Clin Invest. 2024;134(11):e175205. https://doi.org/10.1172/JCI175205.
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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 6

Microglial cell expression of the CB2R induces an activated phenotype and is not regulated by IL-6 signaling.

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Microglial cell expression of the CB2R induces an activated phenotype an...
(A–C) CB2REGFP+ mice were transplanted with B10.BR BM alone or with B10.BR spleen cells. Animals were euthanized 14 days after transplantation. (A) Representative dot plot depicting recipient H-2Kb+ CD45+ CD11b+ microglial cells. (B) Representative histograms depicting EGFP expression on recipient microglial cells from the amygdala, brain stem, cerebellum, and prefrontal cortex of CB2REGFP animals reconstituted with B10.BR BM (BM, red line) or B10.BR BM and spleen cells (GVHD, blue line). (C) Scatterplot showing cumulative median fluorescence intensity (MFI) shifts from 4 replicate experiments. Each data point represents pooled results from 2 mice (n = 8–9 data points). (D) Representative immunofluorescence staining showing CB2R (GFP), microglia (TMEM119), and merged images from the prefrontal cortex of CB2REGFP+ mice transplanted with B10.BR BM and spleen cells. Magnified yellow insert box depicts microglial cell that is CB2R– (blue box) and 1 that expresses the CB2R (green box). Scale bars: 10 μm. (E–G) CB2REGFP+ mice were transplanted with B10.BR BM alone or with B10.BR spleen cells and treated with an anti-IL-6R or isotype control antibody. (E) Representative dot plot depicting recipient H-2Kb+ CD45+ CD11b+ microglial cells. (F) Representative histograms depicting EGFP (CB2R) expression on microglial cells obtained from specified brain regions of CB2REGFP animals reconstituted with B10.BR BM only (BM, red line) or with B10.BR BM and spleen cells and treated with an isotype (GVHD, blue line) or anti-IL-6R antibody (GVHD, αIL-6R, green line). (G) Scatterplot data showing cumulative MFI shifts. Each data point represents pooled results from 2 mice. Results are from 5 experiments (n = 10–15 data points). (H–J) CB2REGFP+ (KI) or B6 mice were transplanted with B10.BR BM alone or with B10.BR spleen cells. Percentage of microglial cells expressing CB2R (EGFP) (H), and frequency of GFP+ (CB2R+) and GFP– (CB2R–) microglia expressing MHC class II, CD80, and CD86 (I and J). Results are from 2 experiments (n = 3–7 mice/group). Data are presented as mean ± SD. Statistics were performed using a t test with Welch’s correction for pairwise comparisons and 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.