Novel insights into the glia limitans of the olfactory nervous system

Lynn Nazareth, Mo Chen, Todd Shelper, Megha Shah, Johana Tello Velasquez, Heidi Walkden, Ifor Beacham, Michael Batzloff, Andrew Rayfield, Michael Todorovic, Kenneth W. Beagley, James A. St John, Jenny A.K. Ekberg*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

19 Citations (Scopus)

Abstract

Olfactory ensheathing cells (OECs) are often described as being present in both the peripheral and the central nervous systems (PNS and CNS). Furthermore, the olfactory nervous system glia limitans (the glial layer defining the PNS–CNS border) is considered unique as it consists of intermingling OECs and astrocytes. In contrast, the glia limitans of the rest of the nervous system consists solely of astrocytes which create a distinct barrier to Schwann cells (peripheral glia). The ability of OECs to interact with astrocytes is one reason why OECs are believed to be superior to Schwann cells for transplantation therapies to treat CNS injuries. We have used transgenic reporter mice in which glial cells express DsRed fluorescent protein to study the cellular constituents of the glia limitans. We found that the glia limitans layer of the olfactory nervous system is morphologically similar to elsewhere in the nervous system, with a similar low degree of intermingling between peripheral glia and astrocytes. We found that the astrocytic layer of the olfactory bulb is a distinct barrier to bacterial infection, suggesting that this layer constitutes the PNS–CNS immunological barrier. We also found that OECs interact with astrocytes in a similar fashion as Schwann cells in vitro. When cultured in three dimensions, however, there were subtle differences between OECs and Schwann cells in their interactions with astrocytes. We therefore suggest that glial fibrillary acidic protein–reactive astrocyte layer of the olfactory bulb constitutes the glia limitans of the olfactory nervous system and that OECs are primarily “PNS glia.”.

Original languageEnglish
Pages (from-to)1228-1244
Number of pages17
JournalJournal of Comparative Neurology
Volume527
Issue number7
DOIs
Publication statusPublished - 1 May 2019
Externally publishedYes

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