Claudia Balducci1, Angelisa Frasca2, Margherita Zotti3, Pietro La Vitola4, Emanuela Mhillaj5, Emanuele Grigoli6, Martina Iacobellis7, Federica Grandi8, Massimo Messa9, Laura Colombo10, Monica Molteni11, Luigia Trabace12, Carlo Rossetti13, Mario Salmona14, Gianluigi Forloni15. 1. Departments of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: claudia.balducci@marionegri.it. 2. Departments of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: angelisa.frasca@gmail.com. 3. Departments of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: margheritazotti@virgilio.it. 4. Departments of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: pietro.lavitola@marionegri.it. 5. Department of Physiology and Pharmacology, La Sapienza University of Rome, 00185 Rome, Italy. Electronic address: emanuela.mhillaj@uniroma1.it. 6. Departments of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: e.grigoli89@gmail.com. 7. Departments of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: m.iacobellis1@campus.unimib.it. 8. Departments of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: federica.grandi@guest.marionegri.it. 9. Departments of Molecular Biochemistry and Pharmacology, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: massimo.messa@humanitasresearch.it. 10. Departments of Molecular Biochemistry and Pharmacology, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: laura.colombo@marionegri.it. 11. Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy. Electronic address: monicamolteni65@gmail.com. 12. Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy. Electronic address: luigia.trabace@unifg.it. 13. Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy. Electronic address: Carlo.Rossetti@uninsubria.it. 14. Departments of Molecular Biochemistry and Pharmacology, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: mario.salmona@marionegri.it. 15. Departments of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy. Electronic address: gianluigi.forloni@marionegri.it.
Abstract
BACKGROUND: Amyloid-β oligomers (AβO) are species mainly involved in the synaptic and cognitive dysfunction in Alzheimer's disease. Although their action has been described mainly at neuronal level, it is now clear that glial cells govern synaptic activity in their resting state, contributing to new learning and memory establishment. In contrast, when activated, they may lead to synaptic and cognitive dysfunction. Using a reliable acute AβO-mediated mouse model of AD, we explored whether the memory alteration AβOs induce relies on the activation of glial cells, and if Toll-like receptor 4 (TLR4), pivotal in the initiation of an immune response, is involved. METHODS: C57 naïve mice were given a single intracerebroventricular injection of synthetic AβO-containing solution (1μM), which induces substantial impairment in the establishment of recognition memory. Then, first we assessed glial cell activation at different times post-injection by western blot, immunohistochemistry and ELISA in the hippocampus. After that we explored the efficacy of pre-treatment with anti-inflammatory drugs (indomethacin and an IL-1β receptor antagonist) to prevent impairment in the novel object recognition task, and compared AβO's effects in TLR4 knockout mice. RESULTS: A single AβO injection rapidly activated glial cells and increased pro-inflammatory cytokine expression. Both anti-inflammatory drugs prevented the AβO-mediated impairment in memory establishment. A selective TLR4 receptor antagonist abolished AβO's action on memory, and in TLR4 knockout mice it had no effect on either memory or glial activation. CONCLUSIONS: These data provide new information on AβO's mechanism of action, indicating that besides direct action at the synapses, they also act through the immune system, with TLR4 playing a major role. This suggests that in a potential therapeutic setting inflammation must be considered as well.
BACKGROUND: Amyloid-β oligomers (AβO) are species mainly involved in the synaptic and cognitive dysfunction in Alzheimer's disease. Although their action has been described mainly at neuronal level, it is now clear that glial cells govern synaptic activity in their resting state, contributing to new learning and memory establishment. In contrast, when activated, they may lead to synaptic and cognitive dysfunction. Using a reliable acute AβO-mediated mouse model of AD, we explored whether the memory alteration AβOs induce relies on the activation of glial cells, and if Toll-like receptor 4 (TLR4), pivotal in the initiation of an immune response, is involved. METHODS: C57 naïve mice were given a single intracerebroventricular injection of synthetic AβO-containing solution (1μM), which induces substantial impairment in the establishment of recognition memory. Then, first we assessed glial cell activation at different times post-injection by western blot, immunohistochemistry and ELISA in the hippocampus. After that we explored the efficacy of pre-treatment with anti-inflammatory drugs (indomethacin and an IL-1β receptor antagonist) to prevent impairment in the novel object recognition task, and compared AβO's effects in TLR4 knockout mice. RESULTS: A single AβO injection rapidly activated glial cells and increased pro-inflammatory cytokine expression. Both anti-inflammatory drugs prevented the AβO-mediated impairment in memory establishment. A selective TLR4 receptor antagonist abolished AβO's action on memory, and in TLR4 knockout mice it had no effect on either memory or glial activation. CONCLUSIONS: These data provide new information on AβO's mechanism of action, indicating that besides direct action at the synapses, they also act through the immune system, with TLR4 playing a major role. This suggests that in a potential therapeutic setting inflammation must be considered as well.
Authors: Ya Gao; Jian Zhang; Shuyue Li; Yidan Zhang; Yuan Zhao; Cui Chang; Ya Qiu; Guofeng Yang Journal: Neurochem Res Date: 2020-11-13 Impact factor: 3.996