Parkin Mediates Cannabidiol Prevention of Amyloid-Beta-Induced Senescence in Human Astrocytes.

Introduction: As aging is the leading risk factor for Alzheimer's disease (AD), ablation of senescent cells is a promising therapeutic approach to prevent AD. It is known that astrocytes lose their ability to maintain a healthy brain environment when aging. Studies have recently shown that cannabidiol (CBD) provides a promising therapeutic avenue for AD; however, if or how CBD prevents astrocyte aging is not known. Materials and Methods: In this study, human astrocytes were employed to measure amyloid-beta (Aβ)-induced senescence features, including senescence-associated β-galactosidase (SA-β-gal), p16INK4A, p21WAF1, and p53. The effects of CBD on the production of mitochondrial dysfunction and mitophagy pathway were measured by Western blot and fluorescence assay. Caenorhabditis elegans was used as in vivo AD model to investigate the effects of CBD on life span and health span. All experimental procedures were approved by the Human Research Ethics Committee, University of Wollongong, Australia. Results: In human astrocytes, we show that treatment with Aβ, an endogenous pathogenic agent of AD, results in an increase in the percentage of SA-β-gal-positive cells and induces mitochondrial reactive oxygen species (ROS). However, CBD treatment protects from Aβ-induced senescence. Furthermore, the anti-senescence and anti-apoptotic activities of CBD were observed to be mediated through the protective effect of Parkin-dependent mitophagy. In C. elegans, we used the transgenic GRU102 strain, which expresses the human Aβ peptide, and found that CBD treatment extended life span, improved pumping rate, and decreased mitochondrial ROS. Conclusion and Significance: Our results demonstrate that CBD prevents the human astrocyte senescence induced by Aβ by a mechanism involving the Parkin-mediated mitophagy pathway. Our findings support the new therapeutic avenues of CBD for the treatment of AD patients.