No abstract

La thérapie biologique de verre bioactif substitué au strontium pour lacicatrisation de tissu mous : les réponses au stress oxydatif chez la rateovariectomisée

Here, we investigated the effect of induction of the Epstein-Barr virus (EBV) viral lytic cycle on the oxidant/antioxidant balance in three lymphoblastoid cell lines: B95-8, Raji, and LCL C1. The induction of the EBV lytic cycle was done by a non-stressing dose of 12-0-tetradecanoylphorbol-13-acetate (8 nM). Oxidative stress was assessed by measuring malondialdehyde as a parameter of lipid peroxidation, the levels of glutathione, and the activities of three antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase). After 48 h (peak of lytic cycle), a significant decrease in superoxide dismutase activity was observed in B95-8, Raji, and LCL C1 cells (P < 0.05). In addition, in B95-8 cells also a significant decrease of catalase activity was detected (P < 0.05). The glutathione peroxidase activity and the glutathione level were not significantly modified by the induction in any of the cell lines. We found a significant rise in malondialdehyde levels in B95-8, Raji, and LCL C1 cells after the induction of the lytic cycle compared to controls (P < 0.05). In conclusion, induction of EBV lytic cycle in lymphoblastoid cells causes increased oxidative stress in the host cells within 48 h, a process that could be involved in malignant transformations.

While latent Epstein-Barr virus infection can be in vitro reactivated by various reagents such as 12-0-tetradecanoylphorbol-13-acetate and calcium ionophore, relatively little is known about in vivo physiological and biochemical factors implicated in this reactivation. Previous studies have described an association between oxidative stress and Epstein-Barr virus infection. In this present study, we investigated the effect of oxidative stress inductors: H2O2 and FeSO4 on reactivation of EBV through BZLF-1 gene expression. Oxidative stress was induced in Raji cell line with 0.2 mM H2O2 or with 0.1 mM FeSO4, and assessed by malondialdehyde level determination, as well as superoxide dismutase and catalase genes expression. Simultaneously, the expression of Epstein-Barr virus immediate-early gene BZLF-1 was analyzed by RT-PCR after 6, 12, 24, 36, and 48 h after H2O2 or FeSO4 treatment. Oxidative stress was evidenced in the Raji cell line by high MDA level as well as superoxide dismutase and catalase genes up-regulation. The transcripts of BZLF-1 were detected from 6 h after 30 min of H2O2 or FeSO4 treatment and maintained until 48 h. These results strongly suggest that oxidative stress contributes to the reactivation of EBV lytic cycle, through induction of BZLF-1 gene expression, a process that may play an important role in the pathogenesis of EBV-associated diseases.