L-ascorbic acid (vitamin C) is one of the well-known anti-viral agents, especially to influenza virus. Since the in vivo anti-viral effect is still controversial, we investigated whether vitamin C could regulate influenza virus infection in vivo by using Gulo (-/-) mice, which cannot synthesize vitamin C like humans. First, we found that vitamin C-insufficient Gulo (-/-) mice expired within 1 week after intranasal inoculation of influenza virus (H3N2/Hongkong). Viral titers in the lung of vitamin C-insufficient Gulo (-/-) mice were definitely increased but production of anti-viral cytokine, interferon (IFN)-α/β, was decreased. On the contrary, the infiltration of inflammatory cells into the lung and production of pro-inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-α/β, were increased in the lung. Taken together, vitamin C shows in vivo anti-viral immune responses at the early time of infection, especially against influenza virus, through increased production of IFN-α/β.

α-Enolase (ENO1) is a multifunctional glycolytic enzyme expressed abundantly in the cytosol. It has been implicated in autoimmune and inflammatory diseases. Serum Abs against ENO1 were reported in rheumatoid arthritis (RA). Cell-surface expression of ENO1 has been found to be increased rapidly in response to inflammatory stimuli, but its expression and function has not been reported in RA. In this study, we show that cell-surface expression of ENO1 is increased on monocytes and macrophages isolated from RA patients but not on those from osteoarthritis patients, and Ab against ENO1 can stimulate these cells to produce higher amounts of proinflammatory mediators, such as TNF-α, IL-1 α/β, IFN-γ, and PGE2 via p38 MAPK and NF-κB pathway. The frequency of ENO1-positive cells in synovial fluid mononuclear cells was higher than PBMCs. ENO1-positive cells were also found in the inflamed synovium from RA patients and arthritic ankle tissues of mice with collagen-induced arthritis. Taken together, these findings suggest that Abs against ENO1 present in RA sera may stimulate monocytes and macrophages expressing cell-surface ENO1 and contribute to production of proinflammatory mediators during the effector phase of synovial inflammation.

Sodium-dependent vitamin C transporters (SVCTs) is known to transport the reduced form of ascorbic acid into the cell, whereas the oxidized form of vitamin C (VC) is moved through a facilitative sugar transporter, such as glucose transporter (GLUT). With regard to the distribution of SVCT1 and -2 within the various organs, they were reported to be expressed in different types of cells. Especially in the central nervous system, only SVCT2 mRNA was expressed mainly in neurons and some types of neuroglial cells. However, data on the expression of SVCT proteins in the brain are scant. Therefore, we tried to develop comprehensive data on the distribution of SVCT proteins in adult rat brain by using immunohistochemical techniques for the first time. In our study, SVCT2 immunoreactivities (IRs) were intensely localized in the neurons of cerebral cortex, hippocampus, and Purkinje cells of cerebellum, and much weaker SVCT2 IRs were found in the other brain regions. Judging from double-immunohistochemical data, most of the cells expressing SVCT2 IRs were likely to be neurons or microglia, even though the cells in choroids plexus or ependymal cells around the ventricles also exhibited SVCT2 IRs. Complete mapping of the distribution of SVCT2 IRs was available by using a semiquantitative method. The subcellular localization of SVCT proteins is necessary for understanding the exact role of the protein, so the current overall mapping of SVCT IRs in the rat brain could be the basis for further studies on related subjects.

The p34SEI-1 protein exerts oncogenic effects via regulation of the cell cycle, which occurs through a direct interaction with cyclin-dependent kinase 4. Such regulation can increase the survival of various types of tumor cells. Here, we show that the antiapoptotic function of p34 SEI-1 increases tumor cell survival by protecting the X-linked inhibitor of apoptosis protein (XIAP) from degradation. Our findings show that p34 inhibits apoptosis. This antiapoptotic effect was eliminated by the suppression of p34 SEI-1 expression. We also determined that direct binding of p34 SEI-1 to the BIR2 domain prevents ubiquitination of XIAP. Interestingly, p34SEI-1 expression is absent or weak in normal tissues but is strongly expressed in tissues obtained from patients with breast cancer. Furthermore, the expression levels of p34 SEI-1 and XIAP seem to be coordinated in human breast cancer cell lines and tumor tissues. Thus, our findings reveal that p34 SEI-1 uses a novel apoptosis-inhibiting mechanism to stabilize XIAP. [Cancer Res 2009;69(3):741-6]

L-ascorbate (L-ascorbic acid, vitamin C) clearly has an inhibitory effect on cancer cells. However, the mechanism underlying differential sensitivity of cancer cells from same tissue to L-ascorbate is yet to be clarified. Here, we demonstrate that L-ascorbate has a selective killing effect, which is influenced by sodium-dependent vitamin C transporter 2 (SVCT-2) in human breast cancer cells. Treatment of human breast cancer cells with L-ascorbate differentially induced cell death, dependent on the SVCT-2 protein level. Moreover, knockdown of endogenous SVCT-2 via RNA interference in breast cancer cells expressing high levels of the protein induced resistance to L-ascorbate treatment, whereas transfection with SVCT-2 expression plasmids led to enhanced L-ascorbate chemosensitivity. Surprisingly, tumor regression by L-ascorbate administration in mice bearing tumor cell xenograft also corresponded to the SVCT-2 protein level. Interestingly, SVCT-2 expression was absent or weak in normal tissues, but strongly detected in tumor samples obtained from breast cancer patients. In addition, enhanced chemosensitivity to L-ascorbate occurred as a result of caspase-independent autophagy, which was mediated by beclin-1 and LC3 II. In addition, treatment with N-acetyl-L-cysteine, a reactive oxygen species (ROS) scavenger, suppressed the induction of beclin-1 and LC3 II, implying that the differential SVCT-2 protein-dependent L-ascorbate uptake was attributable to intracellular ROS induced by L-ascorbate, subsequently leading to autophagy. These results suggest that functional SVCT-2 sensitizes breast cancer cells to autophagic damage by increasing the L-ascorbate concentration and intracellular ROS production and furthermore, SVCT-2 in breast cancer may act as an indicator for commencing L-ascorbate treatment.

Little is known about the cellular characteristics of CD8(+) T cells in rheumatoid arthritis (RA). We addressed this by investigating whether the frequency of the CD8(+) T cell subsets and their phenotypic characteristics are altered in the peripheral blood and synovial fluid (SF) from patients with RA. In this study, CD8(+) T cells, mainly CD45RA(-) effector memory (EM) CD8(+) T cells, were increased significantly in the SF, but not in the peripheral blood from RA patients, compared with healthy controls. The synovial EM CD8(+) T cells were activated phenotypes with high levels of CD80, CD86, and PD-1, and had a proliferating signature in vivo upon Ki-67 staining, whereas the Fas-positive cells were prone to apoptosis. In addition, EM CD8(+) T cells in the SF were less cytotoxic, as they expressed less perforin and granzyme B. In particular, the proportions of synovial fluid mononuclear cells that were CCR4(+)CD8(+) T cells and IL-4-producing CD8(+) T cells (i.e., Tc2 cells) were significantly higher than those in peripheral blood mononuclear cells of patients with RA and healthy controls. In addition, the number of IL-10-producing CD8(+) suppressor T (Ts) cells increased significantly in the SF of RA patients. Especially, CD8(+) T cells were inversely correlated with disease activity. These findings strongly suggest that EM CD8(+) T cells in the SF are increased, likely because of inflammation, and they may be involved in modulating inflammation, thereby affecting the development and progression of RA.

Cancer cells metastasize to the other site after escaping from the immune system and CD70, CD44 and vascular endothelial growth factor (VEGF) play important roles in this process. It is recently reported that interleukin (IL)-18 is closely related with the pathogenesis of skin tumor. Therefore, we investigated the role of endogenous IL-18 from stomach cancer on the immune escape mechanism and metastasis via the regulation of CD70, CD44 and VEGF expression. IL-18 and IL-18R expressions were not only investigated on tumor tissues (n = 10), and sera (n = 20) from stomach cancer patients, but also on human stomach cancer cell lines. IL-18 and IL-18R expressions were found on stomach cancer cell lines and tumor tissues. In addition, IL-18 levels were elevated in sera from cancer patients (P < 0.05), compared with sera from normal individuals. Changes in CD70, CD44 and VEGF expression by flow cytometry, immunoblotting and enzyme-linked immunosorbent assay and immune susceptibility by (51)Cr-release assay were investigated, after silencing or neutralization of endogenous IL-18. CD70 expression was increased and it increases immune susceptibility of cancer cells. In contrast, CD44 and VEGF expression was decreased and it suppresses neovascularization and the metastasis of stomach cancer. After inoculation of IL-18 small interfering RNA (siRNA)-transfected stomach cancer cells into Balb/C (nu/nu) mice, regression of tumor mass was determined by measuring of tumor size. And the number and location of metastatic lesions were investigated by hematoxylin and eosin staining. The regression of tumor mass and the suppression of metastasis were observed in the mice, which are injected with IL-18 siRNA-transfected cell lines. Our data suggest that endogenous IL-18 might facilitate stomach cancer cell immune escape by suppressing CD70 and increasing metastatic ability by upregulating CD44 and VEGF.

DNA methylation plays a major role in the epigenetic regulation of gene expression. Although a few DNA methylation profiling studies of porcine genome which is one of the important biomedical models for human diseases have been reported, the available data are still limited. We tried to study methylation patterns of diverse pig tissues as a study of the International Swine Methylome Consortium to generate the swine reference methylome map to extensively evaluate the methylation profile of the pig genome at a single base resolution. We generated and analysed the DNA methylome profiles of five different tissues and a cell line originated from pig. On average, 39.85 and 62.1% of cytosine and guanine dinucleotides (CpGs) of CpG islands and 2 kb upstream of transcription start sites were covered, respectively. We detected a low rate (an average of 1.67%) of non-CpG methylation in the six samples except for the neocortex (2.3%). The observed global CpG methylation patterns of pigs indicated high similarity to other mammals including humans. The percentage of CpG methylation associated with gene features was similar among the tissues but not for a 3D4/2 cell line. Our results provide essential information for future studies of the porcine epigenome.