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Updated: Mar 8, 2026
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Regulation of Physical Microglia-Neuron Interactions by Fractalkine Signaling after Status Epilepticus
Ukpong B Eyo1, Jiyun Peng1, Madhuvika Murugan1
1Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854; Department of Neurology, Mayo Clinic, Rochester, MN 55905.
Abstract:
Microglia, the resident immune cells of the brain, perform elaborate surveillance in which they physically interact with neuronal elements. A novel form of microglia-neuron interaction named microglial process convergence (MPC) toward neuronal axons and dendrites has recently been described. However, the molecular regulators and pathological relevance of MPC have not been explored. Here, using high-resolution two-photon imaging in vivo and ex vivo, we observed a dramatic increase in MPCs after kainic acid- or pilocarpine-induced experimental seizures that was reconstituted after glutamate treatment in slices from mice. Interestingly, a deficiency of the fractalkine receptor (CX3CR1) decreased MPCs, whereas fractalkine (CX3CL1) treatment increased MPCs, suggesting that fractalkine signaling is a critical regulator of these microglia-neuron interactions. Furthermore, we found that interleukin-1β was necessary and sufficient to trigger CX3CR1-dependent MPCs. Finally, we show that a deficiency in fractalkine signaling corresponds with increased seizure phenotypes. Together, our results identify the neuroglial CX3CL1-CX3CR1 communication axis as a modulator of potentially neuroprotective microglia-neuron physical interactions during conditions of neuronal hyperactivity.
Insights
Microglia interact with neurons via microglial process convergence (MPC). Fractalkine signaling regulates MPC, which may offer neuroprotection during seizures by modulating neuronal hyperactivity.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia, the brain's immune cells, engage in physical surveillance of neurons.
- Microglial process convergence (MPC) is a newly identified interaction between microglia and neuronal axons/dendrites.
- The molecular mechanisms and pathological significance of MPC remain largely unexplored.
Purpose of the Study:
- To investigate the molecular regulators of microglial process convergence (MPC).
- To determine the pathological relevance of MPC in the context of seizures.
- To elucidate the role of fractalkine signaling in microglia-neuron interactions.
Main Methods:
- High-resolution two-photon in vivo and ex vivo imaging.
- Induction of experimental seizures using kainic acid and pilocarpine.
- Genetic manipulation (CX3CR1 deficiency) and pharmacological treatments (fractalkine, interleukin-1β, glutamate).
Main Results:
- Experimental seizures significantly increased MPCs, which were reversed by glutamate treatment.
- Fractalkine receptor (CX3CR1) deficiency reduced MPCs, while fractalkine (CX3CL1) treatment enhanced them.
- Interleukin-1β triggered CX3CR1-dependent MPCs, and impaired fractalkine signaling exacerbated seizure phenotypes.
Conclusions:
- The CX3CL1-CX3CR1 axis is a key regulator of microglia-neuron physical interactions.
- MPC represents a potentially neuroprotective mechanism during neuronal hyperactivity and seizures.
- Understanding this neuroglial communication axis offers insights into epilepsy and neuroinflammation.
