Beta-2 adrenergic receptor agonism alters astrocyte phagocytic activity and has potential applications to psychiatric disease

Abstract

Schizophrenia is a debilitating condition necessitating more efficacious therapies. Previous studies suggested that schizophrenia development is associated with aberrant synaptic pruning by glial cells. We pursued an interdisciplinary approach to understand whether therapeutic reduction in glial cell-specifically astrocytic-phagocytosis might benefit neuropsychiatric patients. We discovered that beta-2 adrenergic receptor (ADRB2) agonists reduced phagocytosis using a high-throughput, phenotypic screen of over 3200 compounds in primary human fetal astrocytes. We used protein interaction pathways analysis to associate ADRB2, to schizophrenia and endocytosis. We demonstrated that patients with a pediatric exposure to salmeterol, an ADRB2 agonist, had reduced in-patient psychiatry visits using a novel observational study in the electronic health record. We used a mouse model of inflammatory neurodegenerative disease and measured changes in proteins associated with endocytosis and vesicle-mediated transport after ADRB2 agonism. These results provide substantial rationale for clinical consideration of ADRB2 agonists as possible therapies for patients with schizophrenia.

Fig. 1

A high-throughput screening approach identified compounds that alter phagocytosis activity in primary human astrocytes. An overview of the screening approach, created with https://www.BioRender.com (A). Normalized dose response for all compounds in the LOPAC and MS compound libraries (B). All colors are consistent with C. Total number of compounds classified as toxic, increasing, increasing at concentrations above 20 µM, decreasing, decreasing at concentrations above 20 µM, or having no effect on phagocytosis (C)

Fig. 2

Increasing doses of salmeterol decrease phagocytosis. Engulfment of pHrodo red-labeled synaptosomes over time following salmeterol doses from 0 to 20 µM (A). Phagocytosis normalized to controls plotted as a function of increasing dose of salmeterol. The area under the curve (AUC) in A was calculated for each dose tested and normalized to the AUC of vehicle-treated controls (0 nM) (B). Cell viability (as measured by calcein AM dye signal) is plotted as a function of increasing dose of salmeterol (C). The red circle indicates a dose that was deemed toxic due to a calcein AM signal of less than 70% of vehicle-treated controls

Fig. 3

PathFX identified network associations between screen drugs and schizophrenia. An example protein–protein interaction network for mabuterol (A). Mabuterol, ADRB2, intermediate network proteins, and the schizophrenia phenotype are represented by an orange triangle, red ellipse, gray ellipses, and a green box, respectively. PathFX used a data-driven approach to identify proteins downstream (gray ellipses) of the ADRB2 target based on the amount and quality of evidence supporting the interactions. Edges connected to schizophrenia were selected from the full network (Supplementary File 3). We also clustered screening drugs using downstream genes discovered by PathFX (B). Screen drugs that increase, decrease, or had no effect on phagocytosis are shown in pink, blue, and purple, respectively, and grey or white indicates the presence or absence of a protein in a drug’s network, respectively

Fig. 4

Mabuterol treatment induced changes in protein and cytokines. Protein level fold-changes from 5XFAD mouse brain tissue that were increased (red) or decreased (blue) significantly (p < 0.05) following mabuterol treatment (A) and corresponding p-values determined via t-test (B). Change in cytokine levels in brain tissue (red/blue = up/down regulated) from 5XFAD mice treated with mabuterol compared to vehicle-treated 5XFAD mice as assessed by Luminex 48-plex (Affymetrix) mouse cytokine assay (*p < 0.05, **p < 0.01, ***p < 0.001; Šidák’s posthoc after 1-way ANOVA) (C) Vascular endothelial factor (VEGF) levels in non-carrier (NC) and 5XFAD mice following vehicle (veh), or mabuterol (mab) treatment (D). MFI = median fluorescent intensity

Fig. 5

An observational study measured the effect of pediatric exposure to ADRB2 agonists on inpatient visits. The study design leveraged a target cohort that included patients with a pediatric treatment with ADRB2 agonists between the ages of 6–18 and a comparator cohort without this treatment. In both cohorts, we considered the outcome of in-patient visits that were associated with a schizophrenia diagnosis (SZ) (A). We measured the hazard ratio between target and comparator groups by fitting a Cox regression model (B). IPW represents a comparison using “inverse probability weighting” to create a balanced comparison among patients accounting for covariates, and “matched” represents a subpopulation of target-comparator patient pairs with similar covariates