• Enduring Changes in Neuronal Function upon Systemic Inflammation Are NLRP3 Inflammasome Dependent.

      Beyer, Marianna M S; Lonnemann, Niklas; Remus, Anita; Latz, Eicke; Heneka, Michael T; Korte, Martin (Society for Neuroscience, 2020-06-04)
      Neuroinflammation can be caused by various insults to the brain and represents an important pathologic hallmark of neurodegenerative diseases including Alzheimer's disease (AD). Infection-triggered acute systemic inflammation is able to induce neuroinflammation and may negatively affect neuronal morphology, synaptic plasticity, and cognitive function. In contrast to acute effects, persisting consequences for the brain on systemic immune stimulation remain largely unexplored. Here, we report an age-dependent vulnerability of wild-type (WT) mice of either sex toward a systemic immune stimulation by Salmonella typhimurium lipopolysaccharide (LPS). Decreased neuronal complexity three months after peripheral immune stimulation is accompanied by impairment in long-term potentiation (LTP) and spatial learning. Aged APP/PS1 mice reveal an increased sensitivity also to LPS of Escherichia coli, which had no effect in WT mice. We further report that these effects are mediated by NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation, since the genetic ablation and pharmacological inhibition using the NLRP3 inhibitor MCC950 rescue the morphological and electrophysiological phenotype.SIGNIFICANCE STATEMENT Acute peripheral immune stimulation has been shown to have both positive and negative effects on Aβ deposition. Improvements or worsening may be possible in acute inflammation. However, there is still no evidence of effects longer than a month after stimulation. The data are pointing to an important role of the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome for mediating the long-term consequences of systemic immune stimulation, which in addition turns out to be age dependent.
    • NLRP3 is activated in Alzheimer's disease and contributes to pathology in APP/PS1 mice.

      Heneka, Michael T; Kummer, Markus P; Stutz, Andrea; Delekate, Andrea; Schwartz, Stephanie; Vieira-Saecker, Ana; Griep, Angelika; Axt, Daisy; Remus, Anita; Tzeng, Te-Chen; et al. (2013-01-31)
      Alzheimer's disease is the world's most common dementing illness. Deposition of amyloid-β peptide drives cerebral neuroinflammation by activating microglia. Indeed, amyloid-β activation of the NLRP3 inflammasome in microglia is fundamental for interleukin-1β maturation and subsequent inflammatory events. However, it remains unknown whether NLRP3 activation contributes to Alzheimer's disease in vivo. Here we demonstrate strongly enhanced active caspase-1 expression in human mild cognitive impairment and brains with Alzheimer's disease, suggesting a role for the inflammasome in this neurodegenerative disease. Nlrp3(-/-) or Casp1(-/-) mice carrying mutations associated with familial Alzheimer's disease were largely protected from loss of spatial memory and other sequelae associated with Alzheimer's disease, and demonstrated reduced brain caspase-1 and interleukin-1β activation as well as enhanced amyloid-β clearance. Furthermore, NLRP3 inflammasome deficiency skewed microglial cells to an M2 phenotype and resulted in the decreased deposition of amyloid-β in the APP/PS1 model of Alzheimer's disease. These results show an important role for the NLRP3/caspase-1 axis in the pathogenesis of Alzheimer's disease, and suggest that NLRP3 inflammasome inhibition represents a new therapeutic intervention for the disease.