EDITORIAL Neuroglia as a Central Element of Neurological Diseases: An Underappreciated Target for Therapeutic Intervention

Neuroglia of the central nervous system (CNS), represented by cells of neural (astrocytes, oligodendrocytes and NG2 glial cells) and myeloid (microglia) origins are fundamental for homeostasis of the nervous tissue. Astrocytes are critical for the development of the CNS, they are indispensable for synaptogenesis, and they define structural organisation of the nervous tissue, as well as the generation and maintenance of CNS-blood and cerebrospinal fluid-blood barriers. Astroglial cells control homeostasis of ions and neurotransmitters and provide neurones with metabolic support. Oligodendrocytes, through the process of myelination, as well as by homoeostatic support of axons provide for interneuronal connectivity. The NG2 cells receive direct synaptic inputs, and might be important elements of adult remyelination. Microglial cells, which originate from foetal macrophages invading the brain early in embryogenesis, shape the synaptic connections through removing of redundant synapses and phagocyting apoptotic neurones. Neuroglia also form the defensive system of the CNS through complex and context-specific programmes of activation, known as reactive gliosis. Many neurological diseases are associated with neurogliopathologies represented by asthenic and atrophic changes in glial cells that, through the loss or diminution of their homeostatic and defensive functions, assist evolution of pathology. Conceptually, neurological and psychiatric disorders can be regarded as failures of neuroglial homeostatic/ defensive responses, and, hence, glia represent a (much underappreciated) target for therapeutic intervention.