Tau fibrils induce glial inflammation and neuropathology via TLR2 in Alzheimer's disease-related mouse models

J Clin Invest. 2023 Sep 15;133(18):e161987. doi: 10.1172/JCI161987.

Abstract

Glial activation and inflammation coincide with neurofibrillary tangle (NFT) formation in neurons. However, the mechanism behind the interaction between tau fibrils and glia is poorly understood. Here, we found that tau preformed fibrils (PFFs) caused induction of inflammation in microglia by specifically activating the TLR2/MyD88, but not the TLR4/MyD88, pathway. Accordingly, the WT TLR2-interacting domain of MyD88 (wtTIDM) peptide inhibited tau PFF-induced activation of the TLR2/MyD88/NF-κB pathway, resulting in reduced inflammation. Nasal administration of wtTIDM in P301S tau-expressing PS19 mice was found to inhibit gliosis and inflammatory markers, as well as to reduce pathogenic tau in the hippocampus, resulting in improved cognitive behavior in PS19 mice. The inhibitory effect of wtTIDM on tau pathology was absent in PS19 mice lacking TLR2, reinforcing the essential involvement of TLR2 in wtTIDM-mediated effects in vivo. Studying the mechanism further, we found that the tau promoter harbored a potential NF-κB-binding site and that proinflammatory molecules increased transcription of tau in neurons via NF-κB. These results suggest that tau-induced neuroinflammation and neuropathology require TLR2 and that neuroinflammation directly upregulates tau in neurons via NF-κB, highlighting a direct connection between inflammation and tauopathy.

Keywords: Alzheimer disease; Cytokines; Inflammation; Neuroscience.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Alzheimer Disease* / pathology
  • Animals
  • Disease Models, Animal
  • Inflammation / pathology
  • Mice
  • Mice, Transgenic
  • Microglia / pathology
  • Myeloid Differentiation Factor 88 / genetics
  • Myeloid Differentiation Factor 88 / metabolism
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • Neuroinflammatory Diseases
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / metabolism
  • tau Proteins / genetics
  • tau Proteins / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • tau Proteins
  • Toll-Like Receptor 2
  • Tlr2 protein, mouse