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Objective Gestational hypertension (GH) is characterized by increased blood pressure after the 20th gestational week; the presence of proteinuria and/or signs of end-organ damage indicate preeclampsia (PE). Heme oxygenase-1 (HO-1) is an antioxidant enzyme with an important role in maintaining endothelial function, and induction of HO-1 by certain molecules shows potential in attenuating the condition's effects over endothelial tissue. HO-1 production can also be stimulated by potassium iodide (KI). Therefore, we evaluated the effects of KI over HO-1 expression in human umbilical vein endothelial cells (HUVECs) incubated with plasma from women diagnosed with GH or PE. Methods Human umbilical vein endothelial cells were incubated with a pool of plasma of healthy pregnant women (n = 12), pregnant women diagnosed with GH (n = 10) or preeclamptic women (n = 11) with or without the addition of KI for 24 hours to evaluate its effect on this enzyme expression. Analysis of variance was performed followed by Dunnet's test for multiple comparisons between groups only or between groups with addition of KI (p ≤ 0.05). Results KI solution (1,000 µM) reduced HO-1 in the gestational hypertension group (p = 0.0018) and cytotoxicity in the preeclamptic group (p = 0.0143); treatment with KI reduced plasma cytotoxicity but did not affect the preeclamptic group's HO-1 expression. Conclusion Our findings suggest that KI alleviates oxidative stress leading to decreased HO-1 expression; plasma from preeclamptic women did not induce the enzyme's expression in HUVECs, and we hypothesize that this is possibly due to inhibitory post-transcriptional mechanisms in response to overexpression of this enzyme during early pregnancy.

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The central role of dendritic cells (DCs) in antigen presentation and induction of antitumor immunity supported the development of antitumor vaccines based on these cells. In previous studies, we have observed that treatment with ultra-low doses of paclitaxel (PAC) modulated human DCs to express the phenotype of mature and activated cells, and stimulated their antigen presentation activity. At the same time, tumor cells treated with low concentrations of drugs became more immunogenic and more susceptible to the lytic activity of cytotoxic T lymphocytes in vitro. Therefore, we aimed to verify if the transfection of DCs with drug-treated tumor cells RNA enhances the effectiveness of DC-based vaccines and if the in vitro effects are reproducible in vivo. Murine colon tumor cells (MC-38) were subcutaneously inoculated in C57Bl/6 mice. At the 10th and 17th days after inoculation, they received a DC vaccine transfected with RNA of MC-38 cells pre-treated with minimum effective concentration of PAC. These DCs expressed 12% higher levels of CD40 and were able to delay the tumor growth when compared with non-treated animals. Although the differences were not significant, our results suggest that the treatment of tumor cells with low concentration of PAC can enhance the immunogenicity of tumor cells, which is transfered for DCs by RNA transfection, and delay tumor growth. Financial support: FAPESP 2009/18331-8; FAPESP 2010/06013-9. Citation Format: Marcela Rodrigues Camargo, Cecília Pessoa Rodrigues, Carolina Mendonça Gorgulho, Fabiana Albani Zambuzi, Victória Elizabeth Galvão, Juliana Cristina Longo Frederico, Marcimara Penitenti, Ramon Kaneno. Minimum effective concentration of paclitaxel improves the effectivity of dendritic cells transfected with tumor RNA. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr B14.