Cribriform Plate Microenvironment Assembles a Suppressive Myeloid Network during EAE-induced Neuroinflammation.

Area of Science:

• Neuroimmunology
• Cerebrospinal Fluid Dynamics
• Cellular Immunology

Background:

• Neuroinflammation involves myeloid cell accumulation at the cribriform plate, a critical cerebrospinal fluid (CSF) outflow site.
• This region features podoplanin (PDPN)-expressing cells and lymphatic vessels, forming a unique drainage microenvironment.
• Experimental autoimmune encephalomyelitis (EAE) serves as a relevant mouse model for studying neuroinflammatory responses.

Purpose of the Study:

• To characterize the myeloid cell populations within the cribriform plate and olfactory bulb meninges during neuroinflammation.
• To investigate the unique expressional signatures of macrophages and dendritic cells (DCs) in this specific anatomical region.
• To understand the role of myeloid cell accumulation in modulating the local immune environment during EAE.

Main Methods:

• Utilized a mouse model of experimental autoimmune encephalomyelitis (EAE) to induce neuroinflammation.
• Employed immunohistochemistry to visualize cell populations and their spatial distribution.
• Applied flow cytometry for quantitative analysis of myeloid cell subsets.
• Conducted single-cell RNA sequencing (scRNAseq) to determine unique gene expression profiles.

Main Results:

• CD11c+CD11b+ myeloid cells were observed to accumulate at the cribriform plate during EAE.
• Macrophages and dendritic cells (DCs) in this region displayed distinct expressional signatures.
• These signatures were associated with pathways related to immune tolerance and cell death.
• A reduced inflammatory profile was noted in myeloid cells at the cribriform plate.

Conclusions:

• Myeloid cell retention at the cribriform plate and olfactory bulb meninges is a key feature of the neuroinflammatory response in EAE.
• These myeloid cells exhibit an immunosuppressive phenotype, contributing to local immune regulation.
• The findings suggest a mechanism by which the brain attempts to control inflammation at a critical CSF outflow site.