Abstract
The brain is an immune-privileged organ such that immune cell infiltration is highly regulated and better tolerating the introduction of antigen to reduce risk of harmful inflammation. Thus, the composition and the nature of the immune response is fundamentally different in the brain where avoiding immunopathology is prioritized compared to other peripheral organs. While the principle of immune privilege in the central nervous system (CNS) still holds true, the role of the immune system in the CNS has been revisited over the recent years. This redefining of immune privilege in the brain is a result of the recent re-discovery of the extensive CNS meningeal lymphatic system and the identification of resident T cells in the brain, meningeal layers, and its surrounding cerebrospinal fluid (CSF) in both humans and rodents. While neuro-immune interactions have been classically studied in the context of neuroinflammatory disease, recent works have also elucidated unconventional roles of immune-derived cytokines in neurological function, highlighting the many implications and potential of neuro-immune interactions. As a result, the study of neuro-immune interactions is becoming increasingly important in understanding both CNS homeostasis and disease. Here, we review the anatomically distinct immune compartments within the brain, the known mechanisms of leukocyte trafficking and infiltration into the CNS and unique transcriptional and functional characteristics of CNS-resident immune cells.
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Funding
This study was supported by grants to D. A. H. from the National Institutes of Health (NIH) (U19 AI089992, R25 NS079193, P01 AI073748, U24 AI11867, R01 AI22220, UM 1HG009390, P01 AI039671, P50 CA121974, and R01 CA227473); the National Multiple Sclerosis Society (NMSS) (CA 1061-A-18 and RG-1802–30153); the Nancy Taylor Foundation for Chronic Diseases, and Erase MS, by grants to. A. W. from the NIH (K08 AI128745, and R01 AI162645); the Pew Charitable Trusts; and the Richard and Susan Smith Family Foundation, and by grants to T. Y. from the NIH (5T32 AI 007019–46).
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D. A. H. has received research funding from Bristol-Myers Squibb, Novartis, Sanofi, and Genentech. He has been a consultant for Bayer Pharmaceuticals, Bristol Myers Squibb, Compass Therapeutics, EMD Serono, Genentech, Juno therapeutics, Novartis Pharmaceuticals, Proclara Biosciences, Sage Therapeutics, and Sanofi Genzyme. Further information regarding funding is available on https://openpaymentsdata.cms.gov/physician/166753/general-payments
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This article is a contribution to the special issue on: Neuroimmune Interactions in Health and Disease - Guest Editors: David Hafler & Lauren Sansing
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Yoshida, T.M., Wang, A. & Hafler, D.A. Basic principles of neuroimmunology. Semin Immunopathol 44, 685–695 (2022). https://doi.org/10.1007/s00281-022-00951-7
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DOI: https://doi.org/10.1007/s00281-022-00951-7