The immune system and the central nervous system | An intimate relationship finally revealed. New landscape or seeing with new eyes?

By: Antigona Ulndreaj and Meital Yerushalmi

“The real voyage of discovery consists not in seeking new landscapes but in having new eyes.”1 This quote by Marcel Proust resonated in my mind while reading the article “Immune Privilege Within the Central Nervous System: It’s Not Always What It Seems” in IMS Magazine’s Winter 2015 issue. As Proust conveys in his book, an artist invests themselves into their art to express reality through their unique viewpoints. Not unlike artists, scientists approach discoveries with their unique set of skills, as they interpret scientific phenomena through their field of expertise.

The immune system and the central nervous system (CNS) have been considered to function independently from each other. Along with other arguments, the absence of lymphatic vessels within the CNS supported the view of an immune-privileged CNS. This notion, however, has been challenged in the past two decades by studies demonstrating the involvement of the immune system in CNS health and disease.

In 2015, the discovery of functional lymphatic vessels in the CNS was the final nail in the coffin of the immune-isolated CNS dogma.2,3 It took a new set of eyes, that of an immunologist, to re-examine the micro-structure of the CNS and bring an end to the dogma. A new era has begun in the field of neuroscience!

Or, has it just begun? Along with commentary articles celebrating the landmark, seeking the answer to this has yielded additional, more intriguing results. Or troubling, should you look at the glass half empty. Publications dating back over half a century have reported the existence of lymphatic vessels in the CNS for the first time.4,5 Could it be that those studies failed to be investigated further because of their disagreement with the immune-isolated CNS dogma?

Resistance to unpopular theories, driven by long-held biases, is not new in research. Yet, this story also highlights the importance of inter-disciplinary collaboration in the quest to answer century-long questions. This discovery necessitates a collaborative re-examination of the CNS, welcoming the emergence of such inter-disciplinary fields as neuroimmunology, psychoneuroimmunology, and neuroendocrinoimmunolgy. Nevertheless, inter-disciplinary science is not immune from dogmas, which may hurdle future discoveries. A fine balance should exist in the peer-review process: similar to the immune system, an overly tolerant review could result in an infectious pandemic of poorly-conducted science; while an overly vigilant review may impede innovative thinking and re-examination of dogmas. Perhaps the focus should be placed on striving for publishing high-quality science, including that which may question an established idea.  

This new era in neuroscience opens the door for exciting research in the field, welcoming curiosity and innovation in exploring the relationship between the immune system and CNS. Most important, it empowers the notion that, so long as science is done rigorously, a debate over and re-examination of dogma should not be feared of. In the words of Marcel Proust, a powerful idea communicates some of its strength to him who challenges it.” 6

 

References:

  1. Proust M. The Captive & The Fugitive: In Search of Lost Time, Vol. V. Enright DJ, editor. New York; London: Modern Library; 1999. 992 p.
  1. Louveau A, Smirnov I, Keyes TJ, Eccles JD, Rouhani SJ, Peske JD, et al. Structural and functional features of central nervous system lymphatic vessels. Nature. 2015 Jul 16;523(7560):337–41.
  1. Aspelund A, Antila S, Proulx ST, Karlsen TV, Karaman S, Detmar M, et al. A dural lymphatic vascular system that drains brain interstitial fluid and macromolecules. J Exp Med. 2015 Jun 29;212(7):991–9.
  1. Bucchieri F, Farina F, Zummo G, Cappello F. Lymphatic vessels of the dura mater: a new discovery? J Anat. 2015 Nov 1;227(5):702–3.
  1. Mezey É, Palkovits M. Neuroanatomy: Forgotten findings of brain lymphatics. Nature. 2015 Aug 27;524(7566):415–415.
  1. Proust M. Remembrance of Things Past. Vol.1. Wordsworth Editions; 2006. 1382 p.