Effets d’extraits de raquette du cactus -Opuntia ficus indica- sur la modulation du stress oxydant et du processus inflammatoire liés à la déficience en acyl-CoA oxydase 1 et caractérisation d’une lignée cellulaire BV-2 inactivée pour l'ACOX 1

Abstract : Acyl-CoA oxidase 1 (ACOX1) deficiency is a rare and severe peroxisomal leukodystrophy associated with a very long-chain fatty acids β-oxidation defect. As peroxisomal defects in microglia appear to be a key component of physiopathogenesis in ACOX1 deficiency, we used the murine BV-2 microglial cell line as model: (i) to evaluate the antioxidant and anti-inflammatory properties of Opuntia ficus-indica cactus cladode extracts; (ii) to characterize a new BV-2 ACOX1 deficient cell line recently generated in our laboratory by CRISPR/Cas9 gene editing. In the first part of this work, the microglia activation, achieved by BV-2 cells exposition to four structurally and biologically well-defined lipopolysaccharides (LPS) serotypes, exhibited a LPS structure-related differential effect on fatty acid β-oxidation and antioxidant enzymes in peroxisomes: LPS derived from Escherichia coli diminished ACOX1 activity while LPS from Salmonella minnesota decreased catalase activity. Interestingly, microglial catalase activity activation was obtained by different cactus extracts. This antioxidant effect was accompanied by an anti-inflammatory effect revealed by the reduction of nitric oxide (NO) LPS-dependent production. Our results suggest that cactus extracts may have a neuroprotective activity in activated microglial cells through the induction of peroxisomal antioxidant activity and the inhibition of NO production. In the second part, the characterization of the BV-2 ACOX1 deficient cell line, with allelic mutations, confirmed the absence of ACOX1 protein and enzymatic activity. Although the mutant cells grew more slowly than control cells, they didn’t show any discernible morphological changes. However, catalase activity, due to the peroxisomal H2O2-degrading enzyme, was significantly enhanced. Subcellular fractionation and ultracentrifugation on Nycodenz gradient studies revealed a relative modification in size and density of peroxisomes in ACOX1-deficient cells. Besides this, ACOX1 deficient cells show a profound modification of inflammatory gene expression (IL-1b, IL-4, TNF-) and particularly of CCL2/MCP-1 protein, which is involved in neuroinflammation. This new Acox1-deficient cell line presents the same biochemical changes shown in the human ACOX1 deficiency and represents a promising model to decipher the consequences of a specific microglial peroxisomal β-oxidation defect on peroxisomal functions, oxidative stress, inflammation and cellular functions.
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Fatima-Ezzahra Saih. Effets d’extraits de raquette du cactus -Opuntia ficus indica- sur la modulation du stress oxydant et du processus inflammatoire liés à la déficience en acyl-CoA oxydase 1 et caractérisation d’une lignée cellulaire BV-2 inactivée pour l'ACOX 1. Médecine humaine et pathologie. Université Bourgogne Franche-Comté; Université Hassan Ier (Settat, Maroc), 2018. Français. ⟨NNT : 2018UBFCI017⟩. ⟨tel-02477187⟩

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