Meningeal Lymphatics: From Anatomy to Central Nervous System Immune Surveillance

Abstract

The parenchyma of the brain is continuously surveyed by its only resident leukocyte, microglia. These cells form a highly specialized population of innate sentinels that is self-renewing and not reliant on hematopoietic replacement (18,19). Although microglia have been ascribed many homeostatic roles, their capacity as APC remains in question. They have been reported to express MHC class II in inflammatory conditions, such as multiple sclerosis, viral infection, and Alzheimer's disease (20)(21)(22)(23), and thus could present Ag to adjacent lymphocytes. There is still much to be learned about the way

Reduced levels of circulating adhesion molecules in adolescents with early-onset psychosis

“…Immune-system dysregulation is suggested to contribute to the pathophysiology of psychotic disorders 11 , and the BBB, the choroid plexus, and the recently discovered specialized lymphatic system of the mammalian brain serve as important interfaces between neuronal and peripheral immune functions [21][22][23] . Because adhesion molecules contribute to the regulation of BBB permeability 24,25 and facilitate leukocyte migration to meningeal spaces and hence to the cerebrospinal fluid (CSF) 21 , they could be relevant to the etiology of various psychiatric and neurological disorders.…”

Live Imaging of Intracranial Lymphatics in the Zebrafish

“…Cerebrospinal fluid produced in the choroid plexus flows into the subarachnoid space where it is believed to be drained by arachnoid villi 36 and the meningeal lymphatic network 4,37 . In addition to draining cerebrospinal fluid and interstitial fluid, the meningeal lymphatic network also drains macromolecules, cellular waste products, and serves as a conduit for trafficking of immune cells 38 . Our studies suggest that zebrafish meningeal lymphatics also drain interstitial and cerebrospinal fluid and actively traffic immune cells, although due to the challenges of imaging very deep structures in juvenile and adult animals the precise drainage points for this network remain to be determined.…”

Can the coronavirus infection penetrates the brain resulting in sudden anosmia followed by severe neurological disorders?

“…Although the CNS lacks the lymphatic attacking system with a minor histocompatibility complex (MHC) molecules, it is usually being protected from invasion by the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CSF) under continual controlled immune surveillance system through brain resident macrophage type and immune regulatory system [ 8 , 9 ]. These brain type macrophages required to be stimulated in case of triggered inflammatory cascading pathways or as a drawback of infection crossed the brain via BBB or even through the olfactory system [ [8] , [9] , [10] ]. Alzheimer's disease (AD) is the most common type of neurodegenerative disorder for an old population mainly characterized by the presence of Aβ and tau protein particularly in the hippocampus and cerebral cortex.…”