Young-il Hwang

α-Enolase Expressed on the Surfaces of Monocytes and Macrophages Induces Robust Synovial Inflammation in Rheumatoid Arthritis

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.

Foxp3 Expression in p53-dependent DNA Damage Responses

The forkhead transcription factor, Foxp3, is thought to act as a master regulator that controls (suppresses) expression of the breast cancer oncogenes, SKP2 and HER-2/ErbB2. However, the mechanisms that regulate Foxp3 expression and thereby modulate tumor development remain largely unexplored. Here, we demonstrate that Foxp3 up-regulation requires p53 function, showing that Foxp3 expression is directly regulated by p53 upon DNA damage responses in human breast and colon carcinoma cells. Treatment with the genotoxic agents, doxorubicin or etoposide, induced Foxp3 expression in p53-positive carcinoma cells, but not in cells lacking p53 function. Furthermore, knock down of endogenous wild-type p53 using RNA interference abrogated Foxp3 induction by genotoxic agents, and exogenous expression of p53 in cells lacking p53 restored the responsiveness of Foxp3 to DNA-damaging stresses. In addition, Foxp3 knock down blunted the p53-mediated growth inhibitory response to DNA-damaging agents. These results suggest that induction of Foxp3 in the context of tumor suppression is regulated in a p53-dependent manner and implicate Foxp3 as a key determinant of cell fate in p53-dependent DNA damage responses.

Vitamin C suppresses proliferation of the human melanoma cell SK-MEL-2 through the inhibition of cyclooxygenase-2 (COX-2) expression and the modulation of insulin-like growth factor II (IGF-II) production†

Vitamin C plays a crucial role in the suppression of proliferation of several types of cancer. Over‐expression of cyclooxygenase (COX)‐2 and type I insulin‐like growth factor (IGF) receptor are important for proliferation and protection from apoptosis in malignancies. However, its specific mechanisms, especially the interaction between COX‐2 expression and IGF‐I axis mediated by vitamin C, remain yet to be clarified. Therefore, we investigated the effects of vitamin C on the proliferation of melanoma cells via the modulation of COX‐2 expression and IGF‐I axis. As a result, we found that 1.0 mM vitamin C inhibits the proliferation of SK‐MEL‐2 without induction of apoptosis. At that moment, IGF‐II production was decreased, followed by the inhibition of COX‐2 activity. IGF‐IR expression was also down‐regulated by vitamin C treatment. It coincided with the result from the inhibition of COX‐2 by NS‐398 and COX‐2 siRNA. In addition, the decreased IGF‐IR expression by vitamin C was restored by the treatment of recombinant prostaglandin E2. Finally, we determined whether the signal pathway would be involved in vitamin C‐induced IGF‐II and IGF‐IR down‐regulation. When the cells were exposed to SB203580, a specific inhibitor of p38 MAPK, COX‐2 expression was dramatically recovered. In addition, phosphorylated p38 MAPK was increased after vitamin C treatment. Taken together, vitamin C suppresses proliferation of the human melanoma cell line SK‐MEL2 via the down‐regulation of IGF‐II production and IGF‐IR expression, which is followed by the activation of p38 MAPK and the inhibition of COX‐2 expression. J. Cell. Physiol. 216: 180–188, 2008.

Characterization of effector memory CD8+ T cells in the synovial fluid of rheumatoid arthritis.

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.

The Analysis of Vitamin C Concentration in Organs of Gulo-/- Mice Upon Vitamin C Withdrawal

Background Vitamin C is an essential nutrient for maintaining human life. Vitamin C insufficiency in the plasma is closely related with the development of scurvy. However, in vivo kinetics of vitamin C regarding its storage and consumption is still largely unknown. Methods We used Gulo-/- mice, which cannot synthesize vitamin C like human. Vitamin C level in plasma and organs from Gulo-/- mice was examined, and it compared with the level of wild-type mice during 5 weeks. Results The significant weight loss of Gulo-/- mice was shown at 3 weeks after vitamin C withdrawal. However, there was no differences between wild-type and vitamin C-supplemented Gulo-/- mice (3.3 g/L in drinking water). The concentration of vitamin C in plasma and organs was significantly decreased at 1 week after vitamin C withdrawal. Vitamin C is preferentially deposited in adrenal gland, lymph node, lung, and brain. There were no significant changes in the numbers and CD4/CD8 ratio of splenocytes in Gulo-/- mice with vitamin C withdrawal for 4 weeks. And the architecture of spleen in Gulo-/- mice was disrupted at 5 weeks after vitamin C withdrawal. Conclusion The vitamin C level of Gulo-/- mice was considerably decreased from 1 week after vitamin C withdrawal. Vitamin C is preferentially stored in some organs such as brain, adrenal gland and lung.

Interleukin-18 increases metastasis and immune escape of stomach cancer via the downregulation of CD70 and maintenance of CD44

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.

Hemolytic uremic syndrome: MR findings of CNS complications.

MR findings of a patient with hemolytic uremic syndrome involving the CNS are described. Abnormal high signal intensity on T2-weighted images combined with swelling in the lentiform nucleus, posterior limb of internal capsule, external capsule bilaterally, and left extreme capsule was shown on initial MR; a small low signal intensity in the left putamen on T1-and T2-weighted images and generalized atrophy in the area of high signal intensity on previous T2-weighted images was shown on follow-up MR. These findings indicate infarct with focal hemorrhage, which is one of the histopathological features of CNS complication in hemolytic uremic syndrome.

Vitamin C-treated murine bone marrow-derived dendritic cells preferentially drive naïve T cells into Th1 cells by increased IL-12 secretions.

Vitamin C has been reported to shift immune responses toward Th1. In this study, we evaluated whether this effect was by way of dendritic cells. Murine dendritic cells (DCs) were prepared from bone marrow precursors. DCs treated with vitamin C secreted an increased amount of IL-12p70 after activation with LPS. These cells rendered naïve T cells to secrete more Th1 cytokine, IFN-γ, and less Th2-cytokine, IL-5 in the culture supernatants. Vitamin C-treatment also increased phosphorylation of p38 and ERK1/2 in DCs. p38 inhibitor in culture media suppressed the effect of vitamin C to elevate IL-12p70 secretion. In contrast, ERK inhibitor elevated IL-12p70 secretion. In summary, vitamin C taken up into DCs increased IL-12p70 secretion of these cells by modulating the activation of signal molecules, and thus shifted immune responses toward Th1. These data provide us a new insight on the role of vitamin C in modulating immune responses.

Vitamin C down‐regulates VEGF production in B16F10 murine melanoma cells via the suppression of p42/44 MAPK activation

It is known that vitamin C induces apoptosis in several kinds of tumor cells, but its effect on the regulation of the angiogenic process of tumors is not completely studied. Vascular endothelial growth factor (VEGF) is the most well‐known angiogenic factor, and it has a potent function as a stimulator of endothelial survival, migration, as well as vascular permeability. Therefore, we have investigated whether vitamin C can regulate the angiogenic process through the modulation of VEGF production from B16F10 melanoma cells. VEGF mRNA expression and VEGF production at protein levels were suppressed by vitamin C. In addition, we found that vitamin C suppressed the expression of cyclooxygenase (COX)‐2 and that decreased VEGF production by vitamin C was also restored by the administration of prostaglandin E2 which is a product of COX‐2. These results suggest that vitamin C suppresses VEGF expression via the regulation of COX‐2 expression. Mitogen‐activated protein kinases are generally known as key mediators in the signaling pathway for VEGF production. In the presence of vitamin C, the activation of p42/44 MAPK was completely inhibited. Taken together, our data suggest that vitamin C can down‐regulate VEGF production via the modulation of COX‐2 expression and that p42/44 MAPK acts as an important signaling mediator in this process. J. Cell. Biochem. 112: 894–901, 2011.

Ancient-to-modern secular changes in Korean stature

Statural growth in human populations is a sensitive indicator of socio-economic well-being, and improvements in socio-economic status are reflected in secular increases in adult height. In the present study, we investigated the statures of historical Korean societies to show how stature changed over time. Applying Fujiis equation, derived from modern Japanese, to the measurement of femora removed from 15th- to 19th-century Joseon tombs, the average heights of Korean adults during the Joseon dynasty were estimated to be 161.1 ± 5.6 cm and 148.9 ± 4.6 cm for males and females, respectively. Plotting statures for successive historical societies against time revealed that Korean heights remained relatively unchanged through to the end of the 19th century, a pattern that differs from that seen in many Western countries in which stature transiently decreases after the Middle Ages. In contrast, a sharp increase in Korean stature was observed at the beginning of the 20th century, similar to trends seen in other nations (although exact timing varies in different countries). There were no accompanying changes of stature sexual dimorphism. The data reported in this study reflect the unique historical experience of Korea; the relative isolation of Joseon society, the late onset of modernization (at the end of the 19th century), and the later occurrence of industrialization (during the 1960s).