Effect of Microglial Purinergic P2Y12 Receptor on Efficiency of Beta-Amyloid Immunotherapy and Aging

Abstract

Microglia, as the primary immune cells of the central nervous system (CNS), play a pivotal role in the efficiency of Aβ immunotherapy by facilitating β-amyloid clearance and forming a protective barrier around β-amyloid plaques. However, the signaling pathways underlying this Aβ antibody-induced effect in microglia remain elusive. P2Y12, a member of the purinergic receptor family expressed by microglia in the CNS, is involved in crucial microglial functions, including directed cell process movement, chemotaxis, and phagocytosis. Therefore, this project aimed to investigate the role of microglial P2Y12 in mediating Aβ clearance and directed cell migration toward plaques during Aβ immunotherapy using microglial cell culture and ex-vivo experimental approaches utilizing confocal microscopy or live-cell imaging. My findings demonstrate that P2Y12 receptor-mediated signaling enhances anti-Aβ antibody-mediated microglial directed cell movement, microglial uptake of synthetic Aβ and Aβ plaque material and contributes to amyloid plaque clearance in the presence of anti-Aβ antibody. Therefore, the study proposed the clinical significance of P2Y12 in mediating the therapeutic effect of developed anti-Aβ immunotherapy. <br> In the aging CNS, chronic inflammation, and adaptive immune responses, such as parenchymal T-cell infiltration, are observed. However, the role of microglia in regulating the adaptive immune response during aging remains poorly understood. P2Y12 has been implicated in cytokine and chemokine release in the aged brain. To investigate the role of P2Y12 for microglial activation in the aged brain, we conducted morphometric and transcriptomic analyses of microglia in adult and aged P2Y12 knockout and wild-type mice. Our transcriptomic analysis revealed a sex-dependent upregulation of activation-related and interferon-responsive genes in microglia from male adult P2Y12 knockout mice compared to wild-type mice. Morphological analysis showed aging-associated changes in microglia from aged P2Y12 knockout and wild-type mice, with fewer cell process ramifications, particularly pronounced in aged male P2Y12 knockout mice. Additionally, there was an exacerbated aging-associated periventricular infiltration of CD8+ T-cells in aged male P2Y12 knockout mice. In-vitro interferon-γ stimulation in primary microglia from P2Y12 knockout mice revealed an exacerbated cytokine and chemokine response, suggesting a role of P2Y12 in facilitating interferon-γ-induced chemokine release in microglia. These findings underscore a potential role of P2Y12 in mitigating aging-related microglial phenotype alterations and T-cell infiltration in a sex-dependent manner.