Brites, Dora Maria Tuna de Oliveira, 1951-Carvalho, Margarida Henriques da Gama, 1972-Lourenço, Maria Queirós Varandas2024-12-1820242024http://hdl.handle.net/10400.5/96474Tese de mestrado, Bioquímica e Biomedicina , 2024, Universidade de Lisboa, Faculdade de CiênciasAlzheimer’s disease (AD) is a progressive neurodegenerative disorder marked by cognitive decline and chronic inflammation, with no treatments able to halt disease progression. Several pro- and antiinflammatory microRNAs (miRNAs), such as miRNA(miR)-124-3p, have been found dysregulated in AD. Previously, our laboratory identified elevated levels of miR-124-3p in SH-SY5Y neuroblastoma cells with the Swedish mutation (APP695) and in PSEN1 mutant neurons. Interestingly, when upregulated, miR-124 improved AD-associated features, causing a reduction in APP expression, Tau phosphorylation and amyloid species. Moreover, soluble and exosomal miR-124 were able to protect microglia activation by interferon-gamma stimulation. To explore the NLRP3-autophagy axis in the context of AD, we assessed relevant markers in the hippocampus and prefrontal cortices of 6- and 9-month-old female and male 5xFAD mice. Additionally, glial activation and synaptic markers were assessed to identify the best conditions for testing our therapeutic approach. We then assessed the effectiveness of the retro-orbital delivery of miR-124-transfected neural exosomes (miR-124-EXOs) in wild-type mice. Lastly, 5xFAD mice were treated with mock/miR-124- transfected EXOs, and cognitive performance was evaluated using behavioral tests. 5xFAD mice at 9- months of age displayed the greatest alterations in messenger RNA (mRNA) levels of Nlrp3/Il1b/Becn1. mRNA levels of Trem2/P2yr12/Cx3cr1/Gfap/Il6/Asc were most significantly increased in female mice. Conversely, Dlg4/Syp mRNA levels were decreased. Western blots of TREM2/S100B supported the activation of glial cells in females and downregulated levels of PSD95 in the hippocampus indicated synaptic loss. Retro-orbital delivery of miR-124-EXOS successfully increased the expression of miR124 up to 14 days post injection. Delivery of mock/miR-124-transfected EXOs to 9-month-old female 5xFAD mice was able to prevent cognitive decline. This study contributes to the understanding of the NLRP3-autophagy axis and inflammatory phenotype of 5xFAD mice. Moreover, it highlights miR-124- EXOs delivery via retro-orbital route as a promising approach to slow AD progression and cognitive loss.engDoença de AlzheimerNeuroinflamaçãoModelo de murganho 5xFADExossomas enriquecidos com miR-124Administração por via retro-orbitalTeses de mestrado - 2024master thesis203880196