Neuroimmune crosstalk in the central nervous system and its significance for neurological diseases

Abstract

The central nervous system (CNS) is now known to actively communicate with the immune system to control immune responses both centrally and peripherally. Within the CNS, while studies on glial cells, especially microglia, have highlighted the importance of this cell type in innate immune responses of the CNS, the immune regulatory functions of other cell types, especially neurons, are largely unknown. How neuroimmune cross-talk is homeostatically maintained in neurodevelopment and adult plasticity is even more elusive. Inspiringly, accumulating evidence suggests that neurons may also actively participate in immune responses by controlling glial cells and infiltrated T cells. The potential clinical application of this knowledge warrants a deeper understanding of the mutual interactions between neurons and other types of cells during neurological and immunological processes within the CNS, which will help advance diagnosis, prevention, and intervention of various neurological diseases. The aim of this review is to address the immune function of both glial cells and neurons, and the roles they play in regulating inflammatory processes and maintaining homeostasis of the CNS.

Morphological evidence of the beneficial role of immune system cells in a rat model of surgical brain injury

“…Microglia clean up the brain parenchyma from damaged cells, infectious factors and cellular debris. Many authors report that the activation of microglial cells is a mark of various pathological situations, such as infection and inflammation, neurodegenerative disorders, is chaemia and different brain injuries [30]. Our electron-microscopic data show that the migration of monocytes and the presence of microglial cells in the injured cortex is observed up to 12 months following the injury.…”

“…It is known that the immune system activation caused by brain injury involves not only the entry of macrophages but also activated resident brain microglia [30]. Our data indicate the massive activation of microglial cells following SBI.…”

“…The clearance of degenerated cells and cellular debris from brain parenchyma can avoid delayed additional injury [30].…”

“…Recent literature data show the presence of intense cross-talk between the nervous and the immune system [13,18,30]. The elements of both systems express and secrete a range of cytokines (for the immune system) and neurotrophic factors (for the CNS) that control growth as well as cell differentiation.…”

Glial and Neuroimmune Mechanisms as Critical Modulators of Drug Use and Abuse

“…Although the immunoregulatory properties of astrocytes are perhaps less appreciated than microglia, astrocytes can also participate in inflammatory signaling within the CNS as well as regulating immune cell trafficking at blood vessels (see Tian et al, 2012). In response to injury or other insults, astrocytes can secrete a variety of neuroimmune signaling molecules, including IL-1α, IL-6, TNFα, and IFN-γ (Lau and Yu, 2001).…”