Comparative analysis of IFN-gamma B7.1 and antisense TGF-beta gene transfer on the tumorigenicity of a poorly immunogenic metastatic mammary carcinoma

Cancer progression is attributed in part to immune evasion strategies that include lack of co-stimulation, down-regulation of cell surface MHC molecules, and secretion of immunosuppressive factors, such as transforming growth factor-beta (TGF-beta). Gene therapy has been employed to counter these mechanisms of immune evasion by transference of B7.1, IFN-gamma or antisense TGF-beta genes into tumor cells, resulting in cell surface expression of B7.1, upregulation of MHC class I and class II molecules, or elimination of tumor-derived TGF-beta, respectively. Although each of these transgenes has been shown to alter tumorigenicity in murine models, a direct comparison of their efficacy has not been performed. In this study, we have employed a very aggressive, poorly immunogenic and highly metastatic mammary model, 4T1, to compare the efficacy of B7.1, IFN-gamma and antisense TGF-beta gene transfer in stimulating an anti-tumor response. We demonstrate that both IFN-gamma and antisense TGF-beta gene expression significantly reduced the tumorigenicity of these cells compared to mock transduced cells, with IFN-gamma having a greater effect. In contrast, B7.1 gene transfer did not affect the tumorigenicity of 4T1 cells. The anti-tumor response directed against antisense TGF-beta-expressing 4T1 tumors was mediated by CD4+ and CD8+ T cells. However, CD8+ T cells, and not CD4+ T cells, appeared to mediate the anti-tumor response against IFN-gamma-expressing tumors. Treatment of tumor-bearing animals with IFN-gamma or antisense TGF-beta gene-modified tumor cell vaccines reduced the number of clonogenic metastases to the lungs and liver compared to treatment with mock-transduced cells. Finally, in a residual disease model in which the primary tumor was excised and mice were vaccinated with irradiated tumor cells, treatment of mice with vaccinations consisting of 4T1 cells expressing both antisense TGF-beta and IFN-gamma genes was the most effective in prolonging survival.     

Platelet Activation in Human Immunodeficiency Virus Type-1 Patients Is Not Altered with Cocaine Abuse

Recent work has indicated that platelets, which are anucleate blood cells, significantly contribute to inflammatory disorders. Importantly, platelets also likely contribute to various inflammatory secondary disorders that are increasingly associated with Human Immunodeficiency Virus Type-1 (HIV) infection including neurological impairments and cardiovascular complications. Indeed, HIV infection is often associated with increased levels of platelet activators. Additionally, cocaine, a drug commonly abused by HIV-infected individuals, leads to increased platelet activation in humans. Considering that orchestrated signaling mechanisms are essential for platelet activation, and that nuclear factor-kappa B (NF-κB) inhibitors can alter platelet function, the role of NF-κB signaling in platelet activation during HIV infection warrants further investigation. Here we tested the hypothesis that inhibitory kappa B kinase complex (IKK) activation would be central for platelet activation induced by HIV and cocaine. Whole blood from HIV-positive and HIV-negative individuals, with or without cocaine abuse was used to assess platelet activation via flow cytometry whereas IKK activation was analyzed by performing immunoblotting and in vitro kinase assays. We demonstrate that increased platelet activation in HIV patients, as measured by CD62P expression, is not altered with reported cocaine use. Furthermore, cocaine and HIV do not activate platelets in whole blood when treated ex vivo. Finally, HIV-induced platelet activation does not involve the NF-κB signaling intermediate, IKKβ. Platelet activation in HIV patients is not altered with cocaine abuse. These results support the notion that non-IKK targeting approaches will be better suited for the treatment of HIV-associated inflammatory disorders.     

Temporal and spatial changes of histone 3 K4 dimethylation at the IFN-gamma gene during Th1 and Th2 cell differentiation

Covalent modification of nucleosomal histones is an important mechanism for cytokine gene regulation in Th1 and Th2 cells. In this study, we analyzed the kinetics of histone H3 K4 dimethylation (H3K4me2) of the IFN-gamma gene. Minimal levels of H3K4me2 were found in naive CD4 T cells. After 5 days of differentiation, H3K4me2 levels were elevated in both Th1 and Th2 cells at the -5.3 kb, the promoter, the intronic DNase I hypersensitive sites, and 3' distal sites including the +9.5 kb and +16 kb sites. Th1 cells maintained high levels of H3K4me2 after longer time of culture. However, in Th2 cells after 14 days, high levels of H3K4me2 were detected only at the -5.3 kb and the promoter, whereas H3K4me2 was lost at the 3' distal sites and greatly diminished at the DNase I hypersensitive sites. After 28 days, Th2 cells lose H3K4me2 at all sites. Unlike the long-term primary Th2 cells, the Th2 clone D10 showed strong H3K4me2 at the IFN-gamma gene with distinctly high levels at the 3' distal sites. CD4 T cells transgenic for Hlx or infected with T-bet-expressing retrovirus produced IFN-gamma and retained high levels of H3K4me2 even after differentiated under Th2 polarizing conditions, suggesting positive roles of these two factors in maintaining high levels of H3K4me2 at the IFN-gamma gene.