Shimpei Ushio

Purification and Characterization of the Human Interleukin-18 Receptor

Interleukin (IL)-18 was identified as a molecule that induces IFN-γ production and enhances NK cell cytotoxicity. In this paper, we report upon the purification and characterization of human IL-18 receptor (hIL-18R). We selected the Hodgkin’s disease cell line, L428, as the most strongly hIL-18R-expressing cell line based on the results of binding assays. This binding was inhibited by IL-18 but not by IL-1β. The dissociation constant (K d ) of125I-IL-18 binding to L428 cells was about 18.5 nm, with 18,000 binding sites/cell. After immunizing mice with L428 cells and cloning, a single monoclonal antibody (mAb) against hIL-18R was obtained (mAb 117-10C). Sequentially, hIL-18R was purified from 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS)-extracted L428 cells by wheat germ lectin-Sepharose 4B chromatography and mAb 117-10C-Sepharose chromatography. The internal amino acid sequences of hIL-18R all matched those of human IL-1 receptor-related protein (IL-1Rrp), the ligand of which was unknown to date. When expressed in COS-1 cells, the cDNA of IL-1Rrp conferred IL-18 binding properties on the cells and the capacity for signal transduction. From these results, we conclude that a functional IL-18 receptor component is IL-1Rrp.

Cloning and expression of interleukin-18 binding protein

Interleukin‐18 binding protein is a novel glycoprotein that we successfully cloned and expressed. First, murine interleukin‐18 binding protein was purified from the sera of mice with endotoxin shock using ligand affinity chromatography. The murine interleukin‐18 binding protein cDNA was cloned after RT‐PCR using mixed primer pair sequences based on partial murine interleukin‐18 binding protein amino acid sequence analysis. Subsequently, human interleukin‐18 binding protein cDNA was cloned from cDNA libraries of normal human liver using murine interleukin‐18 binding protein cDNA as a probe. Next, we transiently expressed recombinant human and murine interleukin‐18 binding proteins in COS‐1 cells and purified them from culture supernatants. Both recombinant interleukin‐18 binding proteins did not exhibit species specificity and prevented interleukin‐18 binding to its receptor. In addition, they inhibited interleukine‐18 dependent IFN‐γ production from KG‐1 cells effectively. These results suggest that the interleukin‐18 binding protein may possess interleukine‐18 antagonist activity.

Royal Jelly prolongs the life span of C3H/HeJ mice: correlation with reduced DNA damage

In this study, we investigate the effect of dietary Royal Jelly (RJ) on tissue DNA oxidative damage and on the life span of C3H/HeJ mice. In C3H/HeJ mice that were fed a dietary supplement of RJ for 16 weeks, the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG), a marker of oxidative stress, were significantly reduced in kidney DNA and serum. Secondly, we determined the effect of dietary RJ on the life span in C3H/HeJ mice. The 50% mice survivals of intermediate- (about 6 mg/kg weight) and high-dose groups (about 60 mg/kg weight) were reached at significantly longer times than that of the control group according to the generalized Wilcoxon test (p<0.05). The average survival times were 88 weeks for the control group vs. 79 weeks for the low-dose group (about 0.6 mg/kg weight), 112 weeks for the intermediate-dose group and 110 weeks for the high-dose group, respectively, showing that RJ extended the average survival time by about 25% compared to the control group. However, RJ did not extend the total life span. These results indicated that dietary RJ increased the average life span of C3H/HeJ mice, possibly through the mechanism of reduced oxidative damage.

Tryptanthrin inhibits nitric oxide and prostaglandin E2 synthesis by murine macrophages

Nitric oxide (NO) and prostaglandins have been implicated in the pathogenesis of several inflammatory diseases. In this study, we investigated the effect of tryptanthrin (6,12-dihydro-6, 12-dioxoindolo-(2,1-b)-quinazoline), an antimicrobial and antitumoral plant compound isolated from Porigonum tinctorium, on NO and prostaglandin E(2) production by interferon-gamma and lipopolysaccharide-stimulated murine macrophage-like RAW 264.7 cells. Tryptanthrin markedly inhibited both NO and prostaglandin E(2) production in a dose-dependent manner. Tryptanthrin at 20 microM fully inhibited expression of inducible NO synthase, suggesting that the inhibitory effect on NO synthesis was mediated by inhibited expression of the enzyme. On the other hand, tryptanthrin had no effect on the levels of cyclooxygenase-2 protein, but inhibited cyclooxygenase enzyme activity with a ICM(50) value of 1.5 microM. Thus, tryptanthrin has the dual functions of inhibiting both NO and prostaglandin E(2) production by activated macrophages, suggesting that tryptanthrin exhibits anti-inflammatory properties.

Identification of a Collagen Production-promoting Factor from an Extract of Royal Jelly and Its Possible Mechanism

We have previously shown that royal jelly (RJ) promoted collagen production by skin fibroblasts in the presence of ascorbic acid-2-O-alpha-glucoside (AA-2G). In this study, we purified the honeybee RJ-derived collagen production-promoting factor (HBRJ-CPF) from an alkali-solubilized fraction of RJ by C18 reverse-phase column chromatography. The elution profile by the C18 column chromatography and the molecular mass of the purified HBRJ-CPF material coincided with those of 10-hydroxy-2-decenoic acid (10H2DA). We then examined the collagen production-promoting activities of several commercially available fatty acids contained in RJ. We found that 10H2DA and 10-hydroxydecanoic acid increased the collagen production in a dose-dependent manner. Furthermore, 10H2DA induced the fibroblast cell line, NHDF, to produce transforming growth factor-β1 (TGF-β1) which is an important factor for collagen production. As expected, the collagen production-promoting activity of 10H2DA was neutralized by the anti-TGF-β1 antibody. These result suggest that HBRJ-CPF identified as 10H2DA promoted the collagen production of AA-2G-treated fibroblasts by inducing TGF-β1 production.

Cell differentiation and apoptosis of monocytic and promyelocytic leukemia cells (U-937 and HL-60) by tryptanthrin, an active ingredient of Polygonum tinctorium Lour.

Tryptanthrin, a bioactive ingredient of Polygonum tinctorium Lour., is a member of the Indigo plant family and has potent cytocidal effects on various human leukemia cells in vitro. At low concentrations, tryptanthrin enhanced the expression of cell differentiation (CD) markers in human monocytic (U‐937) and promyelocytic (HL‐60) leukemia cells indicative of differentiation to monocytes/macrophages. Furthermore, nitroblue tetrazolium (NBT) reductive and α‐naphthyl butyrate esterase (NBE) activities were markedly increased after treatment. Tryptanthrin was more potent than dimethyl sulfoxide (DMSO) at inducing U‐937 cell differentiation into monocytes/macrophages. After treatment with higher concentrations of tryptanthrin for 24 h, cytoplasmic vacuolation and destruction of mitochondria were observed. The leukemia cells died via apoptosis 48 h after treatment. Cytoplasmic vacuolation and apoptotic changes correlated with the dysfunction of mitochondria. Electron microscopic observations revealed marked swelling and destruction of mitochondria after exposure of the leukemia cells to tryptanthrin. Exposure to tryptanthrin enhanced Fas‐induced apoptosis and increased caspase‐3 activity before induction of apoptosis. These results show that low concentrations of tryptanthrin can induce differentiation of leukemia cells but higher concentrations will kill leukemia cells through apoptosis, possibly through a caspase‐3/Fas antigen pathway.

Promoting Effect of Kaempferol on the Differentiation and Mineralization of Murine Pre-osteoblastic Cell Line MC3T3-E1

A number of agents have been reported to influence osteoblastic differentiation and to prevent and treat bone loss. We found that kaempferol, a flavonoid identified in extracts of the medicinal plant, Polygonum tinctorium. Lour, had stimulatory effects on the differentiation and mineralization of the murine pre-osteoblastic cell line, MC3T3-E1. After enhancing the alkaline phosphatase activity, significant augmentation of calcification by kaempferol was observed between concentrations of 10 and 20 μM, without any marked effect on cell proliferation. When kaempferol was combined with ipriflavone, which is clinically applied to treat bone loss, calcification was synergistically augmented, suggesting that these two flavonoids may have different mechanisms of action. These results suggest that kaempferol may be a promising agent for the prevention or treatment of bone loss, especially when combined with ipriflavone.

The natural plant product tryptanthrin ameliorates dextran sodium sulfate-induced colitis in mice.

The therapeutic effects of tryptanthrin (TRYP), a natural product from the medicinal plant Polygonum tinctorium, were examined in a murine model of inflammatory bowel disease (IBD). Colitis was induced by 5% dextran sodium sulfate (DSS) in drinking water for 7 days from day 0. TRYP (100 mg/kg) was administered orally suspended in 5% arabia gum everyday from day 3 for 5 days. Histopathological analysis showed reduced colon damage in TRYP-treated mice on day 6; however, colon injury resumed after treatment was stopped. The production of prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) by untreated and treated mouse colon tissues cultured in vitro were mostly unchanged by TRYP treatment. However, mitogen-stimulated spleen cells from TRYP-treated colitic mice produced less interleukin 2 (IL-2) and less interferon-gamma (IFN-gamma) than untreated colitic mouse spleen cells, early after induction of colitis. When colitis was induced with 5% DSS for 7 days and TRYP was given to the mice for 8 days from day 3, TRYP enhanced the survival of the mice but results were not significant. A significant reduction of weight loss was observed in TRYP-treated mice with colitis induced by 5% DSS for 4 days as compared to control mice. Remarkably, whereas 90% of the vehicle-treated mice died from wasting disease, all the TRYP-treated mice survived, suggesting that TRYP may have a therapeutic effect on colitis.

Preventive effect of Coriandrum sativum (Chinese parsley) on localized lead deposition in ICR mice

The preventive effect of Coriandrum sativum, Fam. UMBELLIFERAE (Chinese parsley) on lead deposition was investigated in male ICR mice given lead (1000 ppm) as lead acetate trihydrate in drinking water for 32 days. Administration of Chinese parsley to mice by gastric intubation was performed for 25 days from day 7 after the start of lead exposure up to the end of the experiment. The mice were then sacrificed for comparison of lead distribution. The lead reached its highest concentration in the femur but localized lead deposition in the femur was significantly decreased by meso-2,3-dimercaptosuccinic acid (DMSA), a chelating agent used as a positive control to validate this experimental model. Administration of Chinese parsley also significantly decreased lead deposition in the femur and severe lead-induced injury in the kidneys. In addition, urinary excretion of delta-aminolevulinic acid (ALA) which is known to increase with lead intake was significantly decreased after administration of Chinese parsley. The MeOH extract of Chinese parsley also reduced lead-induced inhibition of delta-aminolevulinic acid dehydratase (ALAD) activity in vitro. These results suggest that Chinese parsley has suppressive activity on lead deposition, probably resulting from the chelation of lead by some substances contained in Chinese parsley.

Metastasis-Promoting Activity of a Novel Molecule, Ag 243-5, Derived from Mycoplasma, and the Complete Nucleotide Sequence

We found that mycoplasma‐infected cells have a higher ability to metastasize in vivo than non‐mycoplasma‐infected cells. To investigate this phenomenon, we obtained a monoclonal antibody, MAb 243‐5, by immunization with Mycoplasma arginini‐infected RPMI 4788 cells. This MAb recognized a mycoplasmal protein with an MW of 47 kDa and completely inhibited the experimental metastasis of M. arginini‐infected RPMI 4788 cells using a nude mouse model. Using this MAb, we purified a molecule called Ag 243‐5 and determined the N‐terminal amino acid sequence and clarified the entire nucleotide sequence of the Ag 243‐5 gene. PCR analysis showed the existence of a homologous gene in Mycoplasma hyorhinis. Four sequential injections of Ag 243‐5 (30 μg/shot) promoted the experimental metastasis of non‐mycoplasma‐infected RPMI 4788 cells more than 10‐fold using a nude mouse model. Ag 243‐5 also promoted the experimental metastasis of the non‐mycoplasma‐infected mouse colon cancer cell line colon 26. This metastasis‐promoting effect was neutralized by MAb 243‐5.