Th17 lymphocytes drive vascular and neuronal deficits in a mouse model of postinfectious autoimmune encephalitis

Proc Natl Acad Sci U S A. 2020 Mar 24;117(12):6708-6716. doi: 10.1073/pnas.1911097117. Epub 2020 Mar 11.


Antibodies against neuronal receptors and synaptic proteins are associated with a group of ill-defined central nervous system (CNS) autoimmune diseases termed autoimmune encephalitides (AE), which are characterized by abrupt onset of seizures and/or movement and psychiatric symptoms. Basal ganglia encephalitis (BGE), representing a subset of AE syndromes, is triggered in children by repeated group A Streptococcus (GAS) infections that lead to neuropsychiatric symptoms. We have previously shown that multiple GAS infections of mice induce migration of Th17 lymphocytes from the nose into the brain, causing blood-brain barrier (BBB) breakdown, extravasation of autoantibodies into the CNS, and loss of excitatory synapses within the olfactory bulb (OB). Whether these pathologies induce functional olfactory deficits, and the mechanistic role of Th17 lymphocytes, is unknown. Here, we demonstrate that, whereas loss of excitatory synapses in the OB is transient after multiple GAS infections, functional deficits in odor processing persist. Moreover, mice lacking Th17 lymphocytes have reduced BBB leakage, microglial activation, and antibody infiltration into the CNS, and have their olfactory function partially restored. Th17 lymphocytes are therefore critical for selective CNS entry of autoantibodies, microglial activation, and neural circuit impairment during postinfectious BGE.

Keywords: Th17 lymphocyte; autoimmune encephalitis; blood–brain barrier; olfactory circuitry; postinfectious basal ganglia encephalitis.

Publication types

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

MeSH terms

  • Animals
  • Autoantibodies / immunology
  • Basal Ganglia / immunology
  • Basal Ganglia / pathology
  • Blood-Brain Barrier
  • Brain / immunology
  • Brain / pathology*
  • Disease Models, Animal*
  • Encephalitis / etiology*
  • Encephalitis / metabolism
  • Encephalitis / pathology
  • Encephalomyelitis, Autoimmune, Experimental / etiology*
  • Encephalomyelitis, Autoimmune, Experimental / metabolism
  • Encephalomyelitis, Autoimmune, Experimental / pathology
  • Female
  • Hashimoto Disease / etiology*
  • Hashimoto Disease / metabolism
  • Hashimoto Disease / pathology
  • Mice
  • Microglia / immunology
  • Microglia / pathology
  • Neurons / immunology
  • Neurons / pathology
  • Olfaction Disorders / etiology*
  • Olfaction Disorders / metabolism
  • Olfaction Disorders / pathology
  • Olfactory Perception
  • Streptococcal Infections / complications*
  • Streptococcus pyogenes / physiology
  • T-Lymphocytes, Regulatory / immunology
  • T-Lymphocytes, Regulatory / pathology
  • Th17 Cells / immunology*
  • Th17 Cells / pathology


  • Autoantibodies

Supplementary concepts

  • Hashimoto's encephalitis