Toshihiko Hirano

Exosomes Derived from Hypoxic Leukemia Cells Enhance Tube Formation in Endothelial Cells

Background: We recently showed communication between leukemia and endothelial cells and induction of angiogenesis via exosomes. Results: Hypoxic leukemia cells secrete exosomal miRNA, which enhances tube formation in endothelial cells. Conclusion: Exosomal miRNA from a tumor itself helps modulate the microenvironment of the tumor. Significance: This study provides novel insight into the role of exosomes in cancer development. Hypoxia plays an important role during the evolution of cancer cells and their microenvironment. Emerging evidence suggests communication between cancer cells and their microenvironment occurs via exosomes. This study aimed to clarify whether hypoxia affects angiogenic function through exosomes secreted from leukemia cells. We used the human leukemia cell line K562 for exosome-generating cells and human umbilical vein endothelial cells (HUVECs) for exosome target cells. Exosomes derived from K562 cells cultured under normoxic (20%) or hypoxic (1%) conditions for 24 h were isolated and quantitated by nanoparticle tracking analysis. These exosomes were then cocultured with HUVECs to evaluate angiogenic activity. The exosomes secreted from K562 cells in hypoxic conditions significantly enhanced tube formation by HUVECs compared with exosomes produced in normoxic conditions. Using a TaqMan low-density miRNA array, we found a subset of miRNAs, including miR-210, were significantly increased in exosomes secreted from hypoxic K562 cells. We demonstrated that cancer cells and their exosomes have altered miRNA profiles under hypoxic conditions. Although exosomes contain various molecular constituents such as proteins and mRNAs, altered exosomal compartments under hypoxic conditions, including miR-210, affected the behavior of endothelial cells. Our results suggest that exosomal miRNA derived from cancer cells under hypoxic conditions may partly affect angiogenic activity in endothelial cells.

Clinical implication of peripheral CD4+CD25+ regulatory T cells and Th17 cells in myasthenia gravis patients.

Myasthenia gravis (MG) is an autoimmune disorder generally mediated by antibodies against the acetylcholine receptors (AChR) of the skeletal muscles. CD4 T cells help B cells to produce antibodies through their production of cytokines or chemokines. In this study, we evaluated the frequency of regulatory (Treg) and IL-17 producing CD4 T-cell subsets (Th17) in peripheral blood mononuclear cells (PBMCs) of patients with MG. The transcription factor, forkhead transcription factor (Foxp3), is essential for T-cell regulatory function, and the orphan nuclear receptor, RORgammaT, is important in Th17 cell differentiation. In MG patients, Foxp3 mRNA expression in PBMCs was lower than those in healthy subjects (p=0.007), while there was no significant difference of RORgammaT mRNA expression between MG patients and healthy subjects. Glucocorticoid-induced tumour-necrosis-factor receptor-related protein (GITR) is expressed predominantly on CD4(+)CD25(+) Treg cells. We found that the number of GITR(+)CD4(+)CD25(+) T cells in peripheral lymphocytes in MG patients was lower than that in healthy subjects (P<0.01). In addition, there was a significant positive correlation between the change of the frequency of GITR(+)CD4(+)CD25(+) T cells and the changing rate in quantitative myasthenia gravis scores (%) (p=0.03). Furthermore, there was a significant negative correlation between the change of the percentage of GITR(+)CD4(+)CD25(+) T cells (% lymphocytes) and the changing rate of daily PSL doses (%) (P=0.002). The relative RORgammaT levels in PBMCs negatively correlated with the Th1/Th2 ratio in CD4(+) cells in MG patients (p=0.014). In conclusion, our findings suggest that Th17 cells affect the production of autoantibodies through their influence on the Th1- and Th2-cytokine balance in PBMCs of MG patients. On the other hand, Treg cells are suggested to be involved in the clinical condition or severity of MG disease.

Effects of Naturally Occurring Polymethyoxyflavonoids on Cell Growth, P-Glycoprotein Function, Cell Cycle, and Apoptosis of Daunorubicin-Resistant T Lymphoblastoid Leukemia Cells

ABSTRACT Effects of polymethoxyflavonoids tangeretin and nobiletin and the related polyphenolic compounds baicalein, wogonin, quercetin, and epigallocatechin gallate on the cell growth, P-glycoprotein function, apoptosis, and cell cycle of human T lymphoblastoid leukemia MOLT-4 and its daunorubicin-resistant cells were investigated. The IC50 values of these compounds on the cell growth were 7.1–32.2 μmol/L, and the inhibitory effects were observed to be almost equal to the parent MOLT-4 and the daunorubicin-resistant cells. Tangeretin and nobiletin showed the strongest effects with the IC50 values of 7.1–14.0 μmol/L. These polymethoxyflavonoids inhibited the P-glycoprotein function and significantly influenced the cell cycle (p<.05), whereas they did not induce apoptosis.

Sofalcone, a gastric mucosa protective agent, increases vascular endothelial growth factor via the Nrf2-heme-oxygenase-1 dependent pathway in gastric epithelial cells

Sofalcone, 2-carboxymethoxy-4,4-bis(3-methyl-2-butenyloxy)chalcone, is an anti-ulcer agent that is classified as a gastric mucosa protective agent. Recent studies indicate heat shock proteins such as HSP32, also known as heme-oxygenase-1(HO-1), play important roles in protecting gastrointestinal tissues from several stresses. We have previously reported that sofalcone increases the expression of HO-1 in adipocytes and pre-adipocytes, although the effect of sofalcone on HO-1 induction in gastrointestinal tissues is not clear. In the current study, we investigated the effects of sofalcone on the expression of HO-1 and its functional role in rat gastric epithelial (RGM-1) cells. We found that sofalcone increased HO-1 expression in RGM-1 cells in both time- and concentration-dependent manners. The HO-1 induction was associated with the nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in RGM-1 cells. We also observed that sofalcone increased vascular endothelial growth factor (VEGF) production in the culture medium. Treatment of RGM-1 cells with an HO-1 inhibitor (tin-protoporphyrin), or HO-1 siRNA inhibited sofalcone-induced VEGF production, suggesting that the effect of sofalcone on VEGF expression is mediated by the HO-1 pathway. These results suggest that the gastroprotective effects of sofalcone are partly exerted via Nrf2-HO-1 activation followed by VEGF production.

Proton Pump Inhibitors Decrease Soluble fms-Like Tyrosine Kinase-1 and Soluble Endoglin Secretion, Decrease Hypertension, and Rescue Endothelial Dysfunction.

Preeclampsia is a severe complication of pregnancy. Antiangiogenic factors soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin are secreted in excess from the placenta, causing hypertension, endothelial dysfunction, and multiorgan injury. Oxidative stress and vascular inflammation exacerbate the endothelial injury. A drug that can block these pathophysiological steps would be an attractive treatment option. Proton pump inhibitors (PPIs) are safe in pregnancy where they are prescribed for gastric reflux. We performed functional studies on primary human tissues and animal models to examine the effects of PPIs on sFlt-1 and soluble endoglin secretion, vessel dilatation, blood pressure, and endothelial dysfunction. PPIs decreased sFlt-1 and soluble endoglin secretion from trophoblast, placental explants from preeclamptic pregnancies, and endothelial cells. They also mitigated tumor necrosis factor-&agr;–induced endothelial dysfunction: PPIs blocked endothelial vascular cell adhesion molecule-1 expression, leukocyte adhesion to endothelium, and disruption of endothelial tube formation. PPIs decreased endothelin-1 secretion and enhanced endothelial cell migration. Interestingly, the PPI esomeprazole vasodilated maternal blood vessels from normal pregnancies and cases of preterm preeclampsia, but its vasodilatory effects were lost when the vessels were denuded of their endothelium. Esomeprazole decreased blood pressure in a transgenic mouse model where human sFlt-1 was overexpressed in placenta. PPIs upregulated endogenous antioxidant defenses and decreased cytokine secretion from placental tissue and endothelial cells. We have found that PPIs decrease sFlt-1 and soluble endoglin secretion and endothelial dysfunction, dilate blood vessels, decrease blood pressure, and have antioxidant and anti-inflammatory properties. They have therapeutic potential for preeclampsia and other diseases where endothelial dysfunction is involved.

Rewarming preservation by organ perfusion system for donation after cardiac death liver grafts in pigs.

BACKGROUNDnUse of grafts from donors after cardiac death (DCD) would greatly contribute to the expansion of the donor organ pool. However, this requires the development of novel preservation methods to recover the organ from changes due to warm ischemia time (WIT).nnnMETHODSnPorcine livers were perfused with a newly developed machine perfusion (MP) system. The livers were perfused with modified University of Wisconsin solution (UW) - gluconate. All grafts were procured after acute hemorrhagic shock with the ventilator off. For group 1 (n = 6), grafts were procured after WIT of 60 minutes and preserved by hypothermic MP (HMP) for 3 hours. For group 2 (n = 5), grafts were preserved with 2 hours of simple cold storage (SCS) and HMP for 2 hours. For group 3 (n = 6), grafts were preserved with 2 hours of SCS and rewarming up to 25°C by MP for 2 hours (RMP). The preserved liver grafts were transplanted orthotopically.nnnRESULTSnThe alanine aminotransferase level in perfusate in RMP during perfusion preservation was maintained at less than that of HMP. The levels of aspartate aminotransferase and lactate dehydrogenase in the 2 hours after reperfusion were significantly lower in group 3. Histologically, the necrosis of hepatocytes was less severe in group 3. The survival rate in group 3 was 2/4, but 0/4 in the other group.nnnCONCLUSIONnRMP is expected to facilitate the recovery of the DCD liver grafts.

Pretransplant Screening and Evaluation of Liver Graft Viability Using Machine Perfusion Preservation in Porcine Transplantation

A novel method using machine perfusion for pretransplant screening and evaluation of the viability of liver grafts has been proposed, seeking to prevent severe ischemia-reperfusion injury and to reduce the risk of primary graft nonfunction. This study sought to evaluate the viability of critical grafts, which were obtained from expanded criteria donors or donation after cardiac death donors during preservation with a new machine preservation perfusion system (NES-01). The normalized pressure transition in the hepatic artery was employed as an evaluation index for liver viability. As a result, the normalized pressure (p/p(0)) in the hepatic artery showed a distinctive transition under each experimental conditions controlled by warm ischemic time (WIT). The high viability graft, obtained under the condition of WIT as 0 minutes (WIT0), showed a quick response to hepatic artery pressure after initiating perfusion, whereas the normalized pressure showed a sudden decrease. In contrast, the normalized pressure among WIT60, which may cause the graft to lose viability, showed a poor hepatic artery response. These findings corresponded to the cumulative release of enzymes. The findings of our study suggest that monitoring of the pressure drop rate in the hepatic artery during machine perfusion can be used to evaluate liver graft viability.

Involvement of oxidative stress associated with glutathione depletion and p38 mitogen-activated protein kinase activation in arsenic disulfide-induced differentiation in HL-60 cells

Abstract Arsenic disulfide (As2S2) has been traditionally used to treat certain types of leukemia. However, a detailed mechanism of action of As2S2 is not sufficiently documented. The effects of As2S2 on HL-60 cells were therefore investigated by focusing on proliferation, differentiation, generation of reactive oxygen species (ROS), intracellular glutathione (GSH) depletion and activation of p38 mitogen-activated protein kinase (MAPK). As2S2 at 0.5–8 μM induced cell differentiation based on an increment in CD11b expression, nitroblue tetrazolium (NBT)-positive cells and cell size change. A transient increase in ROS level along with intracellular GSH level was also observed. p38 MAPK activation gradually increased after ROS generation and was sustained during cell differentiation. Decreased CD11b expression was accompanied by p38 MAPK activation, and a p38 MAPK inhibitor restored CD11b expression. The results suggest that moderate levels of oxidative stress induced by As2S2 correlate with HL-60 cell differentiation. Suppression of p38 MAPK can augment the efficacy of As2S2 to induce HL-60 cell differentiation.

Azithromycin suppresses proliferation, interleukin production and mitogen-activated protein kinases in human peripheral-blood mononuclear cells stimulated with bacterial superantigen

Objectivesu2002 Macrolide antibiotics are used for the treatment of immunological disorders such as psoriasis. However, few studies have investigated the immunoregulatory efficacy of macrolides in bacterial superantigen‐stimulated immune cells.

Polymethoxyflavonoids Tangeretin and Nobiletin Increase Glucose Uptake in Murine Adipocytes

Tangeretin and nobiletin are polymethoxyflavonoids that are contained in citrus fruits. Polymethoxyflavonoids are reported to have several biological functions including anti‐inflammatory, anti‐atherogenic, or anti‐diabetic effects. However, whether polymethoxyflavonoids directly affect glucose uptake in tissues is not well understood. In the current study, we investigated whether tangeretin and nobiletin affect glucose uptake in insulin target cells such as adipocytes. We observed that treatment with tangeretin or nobiletin significantly increased the uptake of [3H]‐deoxyglucose in differentiated 3T3‐F442A adipocytes in a concentration‐dependent manner. Data showed that phosphatidyl inositol 3 kinase, Akt1/2, and the protein kinase A pathways were involved in the increase in glucose uptake induced by polymethoxyflavonoids. These data suggest that the anti‐diabetic action of polymethoxyflavonoids is partly exerted via these signaling pathways in insulin target tissues. Copyright