Analysis of swine leukocyte antigen class I gene profiles and porcine endogenous retrovirus viremia level in a transgenic porcine herd inbred for xenotransplantation research.

Molecular characterization of swine leukocyte antigen (SLA) genes is important for elucidating the immune responses between swine-donor and human-recipient in xenotransplantation. Examination of associations between alleles of SLA class I genes, type of pig genetic modification, porcine endogenous retrovirus (PERV) viral titer, and PERV subtypes may shed light on the nature of xenograft acceptance or rejection and the safety of xenotransplantation. No significant difference in PERV gag RNA level between transgenic and non-transgenic pigs was noted; likewise, the type of applied transgene had no impact on PERV viremia. SLA-1 gene profile type may correspond with PERV level in blood and thereby influence infectiveness. Screening of pigs should provide selection of animals with low PERV expression and exclusion of specimens with PERV-C in the genome due to possible recombination between A and C subtypes, which may lead to autoinfection. Presence of PERV-C integrated in the genome was detected in 31.25% of specimens, but statistically significant increased viremia in specimens with PERV-C was not observed. There is a need for multidirectional molecular characterization (SLA typing, viremia estimation, and PERV subtype screening) of animals intended for xenotransplantation research in the interest of xeno-recipient safety.

Contribution of reactive oxygen species to the anticancer activity of aminoalkanol derivatives of xanthone.

Reactive oxygen species (ROS) are critically involved in the action of anticancer agents. In this study, we investigated the role of ROS in the anticancer mechanism of new aminoalkanol derivatives of xanthone. Most xanthones used in the study displayed significant pro-oxidant effects similar to those of gambogic acid, one of the most active anticancer xanthones. The pro-oxidant activity of our xanthones was shown both directly (by determination of ROS induction, effects on the levels of intracellular antioxidants, and expression of antioxidant enzymes) and indirectly by demonstrating that the overexpression of manganese superoxide dismutase decreases ROS-mediated cell senescence. We also observed that mitochondrial dysfunction and cellular apoptosis enhancement correlated with xanthone-induced oxidative stress. Finally, we showed that the use of the antioxidant N-acetyl-L-cysteine partly reversed these effects of aminoalkanol xanthones. Our results demonstrated that novel aminoalkanol xanthones mediated their anticancer activity primarily through ROS elevation and enhanced oxidative stress, which led to mitochondrial cell death stimulation; this mechanism was similar to the activity of gambogic acid.

Modulation of porcine endogenous retroviruses (PERVs) expression in vitro by shRNA in the presence of cyclosporine A and dexamethasone.

BACKGROUND: Despite the fact that the risk of Porcine Endogenous Retroviruses (PERV) infection and propagation in human recipients is extremely low, such an event cannot be completely ruled out, especially in immunosuppressed patients. Therefore, the aim of this study was to analyze the expression of PERVs in vitro in the presence of immunosuppression agents: cyclosporine A (CsA), and dexamethasone (DEX). We investigated the possible interactions between immunosuppression drugs, CsA and DEX, and the efficiency of anti-PERV RNAi. MATERIAL/METHODS: Plasmid-based vectors expressing shRNAs against all PERV genes were constructed and analyzed. PERVs expression in cultures transfected with anti-PERV RNAi constructions and treated with CsA or DEX was analyzed by Real-Time RT-PCR, Western blot, and by the measurement of RT activity. RESULTS: Both CsA and DEX inhibited PERVs expression in cell cultures in vitro. RNAi constructions efficiently knocked down PERV expression in Circe, and de novo PERV-infected HeLa and HEK-293 cell cultures. Pretreatment of Circe cultures with CsA or DEX increased PERVs knockdown by RNAi, but no specific interaction between the drugs and transfection efficiency was observed. CONCLUSIONS: Our results demonstrate that cyclosporine A and dexamethasone decrease expression of PERVs in vitro. We also proved that these drugs did not synergize or antagonize RNAi-mediated knockdown of PERVs. These observations may be beneficial in immunosuppressed xenograft recipients; however, due to the controversial literature data concerning influence of immune suppression on graft recipients, our results should be further analyzed.