Microglial Remodeling of the Extracellular Matrix Promotes Synapse Plasticity

Cell. 2020 Jul 23;182(2):388-403.e15. doi: 10.1016/j.cell.2020.05.050. Epub 2020 Jul 1.

Abstract

Synapse remodeling is essential to encode experiences into neuronal circuits. Here, we define a molecular interaction between neurons and microglia that drives experience-dependent synapse remodeling in the hippocampus. We find that the cytokine interleukin-33 (IL-33) is expressed by adult hippocampal neurons in an experience-dependent manner and defines a neuronal subset primed for synaptic plasticity. Loss of neuronal IL-33 or the microglial IL-33 receptor leads to impaired spine plasticity, reduced newborn neuron integration, and diminished precision of remote fear memories. Memory precision and neuronal IL-33 are decreased in aged mice, and IL-33 gain of function mitigates age-related decreases in spine plasticity. We find that neuronal IL-33 instructs microglial engulfment of the extracellular matrix (ECM) and that its loss leads to impaired ECM engulfment and a concomitant accumulation of ECM proteins in contact with synapses. These data define a cellular mechanism through which microglia regulate experience-dependent synapse remodeling and promote memory consolidation.

Keywords: microglia, hippocampus, extracellular matrix, aging, memory, dendrite remodeling, interleukin-33.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aging
  • Animals
  • Extracellular Matrix / metabolism*
  • Fear
  • Gene Expression Regulation
  • Hippocampus / metabolism
  • Interleukin-1 Receptor-Like 1 Protein / genetics
  • Interleukin-1 Receptor-Like 1 Protein / metabolism
  • Interleukin-33 / genetics
  • Interleukin-33 / metabolism
  • Memory
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Microglia / physiology*
  • Neuronal Plasticity / physiology*
  • Neurons / metabolism
  • Signal Transduction

Substances

  • Interleukin-1 Receptor-Like 1 Protein
  • Interleukin-33