The roles of astrocytic phagocytosis in maintaining homeostasis of brains

In the central nervous system, microglia are regarded as the main cells responsible for phagocytosis, contributing to neural circuit refinement and homeostasis through synapse elimination. However, recent findings have shown that astrocytes also actively participate in synapse homeostasis through phagocytosing synapses, neuronal debris, axonal mitochondria, and pathological protein aggregates. In addition, it has been also suggested that astrocytes may regulate microglial phagocytosis by secreting molecules such as IL-33 and C3. Here, we have introduced key findings regarding direct and indirect astrocyte-mediated phagocytosis in CNS development, the sleep/wake cycle, and aging. We have also discussed current information about reactive astrocytes and their phagocytic function in the diseased brain, focusing on ischemia and Alzheimer's disease. Through this review, we aim to provide an overview of the current status as well as future perspectives regarding the important role of astrocytic control of phagocytosis. (C) 2020 The Authors. Production and hosting by Elsevier B.V. on behalf of Japanese Pharmacological Society.

Automated summary

This article introduces the role of astrocytes in the central nervous system in phagocytizing synapses, neuronal debris, and other substances to contribute to neural circuit refinement and homeostasis. It also discusses the potential regulation of microglial phagocytosis by astrocytes through secretion of molecules, as well as the involvement of reactive astrocytes in diseased brains.