Characterization of secretory type IIA phospholipase A2 (sPLA2-IIA) as a glycyrrhizin (GL)-binding protein and the GL-induced inhibition of the CK-II-mediated stimulation of sPLA2-IIA activity in vitro

Protein Kinase CK2 Maintains Reciprocal Balance Between Th17 and Treg Cells in the Pathogenesis of UC

BACKGROUND

T helper 17 and regulatory T cells balance have crucial effects on the development of ulcerative colitis (UC). Currently, how to break this balance has not yet been found. Protein kinase CK2 is involved in the pathogenesis of immune-related disorders. However, its effects on the development of UC are obscure.

METHODS

The level of CK2 in the colonic tissues of UC patients was quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and immune-histochemistry. Peripheral blood CD4+ T cells were treated with CK2 inhibitor CX4945 or transfected with Csnk2-interfering lentivirus; the mRNA expression and protein levels of inflammatory cytokines were detected by qRT-PCR, enzyme-linked immunosorbent assay, and flow cytometry. Moreover, CX4945 was administered to trinitrobenzene sulfonic acid (TNBS)-induced colitis mice model for determining the function of CK2 on the regulation of intestinal inflammation.

RESULTS

The CK2 level was markedly increased in inflamed mucosa of UC and highly expressed in CD4+ T cells. Blockade of CK2 by CX4945 inhibited Th17 but promoted regulatory T-cell (Treg) immune responses in CD4+ T cells from patients with UC. Moreover, CK2 blockade alleviated TNBS-induced colitis in mice. Inhibition of CK2 suppressed Th17 but promoted Treg differentiation by decreasing the phosphorylation level of signal transducer and activator of transcription (STAT) 3 and increasing the phosphorylation level of STAT5. The RNA-Seq and co-immunoprecipitation analysis further showed that CK2 could interact with Sirtuin 1 (SIRT1) and downregulate SIRT1 expression, which participated in Th17 inhibition but promoted Treg differentiation. Sirtuin 1 upregulation ameliorated TNBS-induced colitis, whereas SIRT1 blockade aggravated TNBS-induced colitis in mice.

CONCLUSIONS

CK2 have crucial effects on the development of UC by maintaining reciprocal balance between Th17 and Treg cells. Protein kinase CK2 blockade might be considered as a new therapeutic approach for UC treatment.

The genus Glycyrrhiza (Fabaceae family) and its active constituents as protective agents against natural or chemical toxicities

Licorice is the dried roots and rhizomes of various species of the genus Glycyrrhiza (Fabaceae) that have been used in folk medicine from ancient times. Many important research projects have established several beneficial effects for this medicinal herb, including antiinflammatory, antimicrobial, antiviral, antiprotozoal, antioxidant, antihyperglycemic, antihyperlipidemic, hepatoprotective, and neuroprotective. Licorice contains important bioactive components, such as glycyrrhizin (glycyrrhizic, glycyrrhizinic acid), liquiritigenin, liquiritin, and glycyrrhetinic acid. The protective effects of licorice and its main chemical components against toxins and toxicants in several organs including the brain, heart, liver, kidney, and lung have been shown. In this comprehensive review article, the protective effects of these constituents against natural, industrial, environmental, and chemical toxicities with attention on the cellular and molecular mechanism are introduced. Also, it has been revealed that this plant and its main compounds can inhibit the toxicity of different toxins by the antioxidant, antiinflammatory, and anti-apoptotic properties as well as the modulation of Inhibitor of kappaB kinase (IKK), Extracellular signal-regulated protein kinase1/2 (ERK1/2), p38, inducible nitric oxide synthase, and nuclear factor-κB (NF-κB) signaling pathways. More high-quality investigations in both experimental and clinical studies need to firmly establish the efficacy of licorice and its main constituents against toxic agents.

Inhibitory Effect of Pelargonidin on Secretory Group IIA Phospholipase A2

The expression of secretory group IIA phospholipase A2 (sPLA2-IIA) has been shown to be elevated in various inflammatory diseases, and lipopolysaccharide (LPS) up-regulates the expression of sPLA2-IIA in human umbilical vein endothelial cells (HUVECs). Pelargonidin (PEL) is a well-known red pigment found in plants, and has been reported as having important biological activities that are potentially beneficial for human health. Here, PEL was examined for its effects on the expression and activity of sPLA2-IIA in HUVECs and mouse. Post treatment of cells or mouse with PEL inhibited LPS-induced expression and activity of sPLA2-IIA. Therefore, these results suggest that PEL inhibited LPS mediated expression of sPLA2-IIA.

Inhibitory Effect of Zingerone on Secretory Group IIA Phospholipase A2

The expression of secretory group IIA phospholipase A2 (sPLA2-IIA) has been shown to be elevated in various inflammatory diseases, and lipopolysaccharide (LPS) up-regulates the expression of sPLA2-IIA in human umbilical vein endothelial cells (HUVECs). Zingerone (ZGR), a phenolic alkanone isolated from ginger, has been reported to have various pharmacological activities. Here, we examined the effects of ZRG on the expression and activity of sPLA2-IIA in LPS-activated HUVECs and in mouse models of endotoxemia and sepsis. Treatment of cells or mice with ZRG inhibited LPS-induced expression and activity of sPLA2-IIA. In addition, ZRG suppressed LPS-mediated activation of cytosolic phospholipase A2 (cPLA2) and extracellular signal-regulated kinase (ERK) 1/2. These results suggest that ZRG inhibits LPS-mediated activation of sPLA2-IIA expression by suppressing cPLA2 and ERK 1/2.

Inhibitory Effect of Three Diketopiperazines from Marine-derived Bacteria on Secretory Group IIA Phospholipase A2

Diketopiperazines, natural products found in bacteria, fungi, marine sponges, gorgonian and red algae, are cyclic dipeptides possessing relatively simple and rigid structures with chiral nature and various side chains. The compounds in this structure class have been known to possess diverse bioactivities including antibiotic activity, anti-cancer activity, neuroprotective activity, and anti-inflammatory activity. The expression of secretory group IIA phospholipase A2 (sPLA2-IIA) is enhanced by development of inflammatory disorders. Aim of this study is to determine the effects of diketopiperazines on the secretion and activity of sPLA2-IIA by lipopolysaccharide (LPS) in human umbilical vein endothelial cells (HUVECs). To do this, sPLA2-IIA expression was induced in the LPS-stimulated HUVECs and mice to evaluate the effect of diketopiperazines. Results showed that diketopiperazines remarkably suppressed the LPS-mediated protein expression and activity of sPLA2-IIA via inhibition of phosphorylation of cytosolic phospholipase A2 (cPLA2) and extracellular signal-regulated kinase (ERK) 1/2. These results demonstrated that diketopiperazines might play an important role in the modulation of sPLA2-IIA expression and activity in response to the inflammatory diseases.

Inhibitory Effect of FXa on Secretory Group IIA Phospholipase A2

It is well known that the expression level of secretory group IIA phospholipase A2 (sPLA2-IIA) is elevated in inflammatory diseases and lipopolysaccharide (LPS) upregulates the expression of sPLA2-IIA in human umbilical vein endothelial cells (HUVECs). Activated factor X (FXa) is an important enzyme in the coagulation cascade responsible for thrombin generation, and it influences cell signaling in various cell types by activating protease-activated receptors (PARs). Here, FX or FXa was examined for its effects on the expression and activity of sPLA2-IIA in HUVECs and mouse. Prior treatment of cells or mouse with FXa inhibited LPS-induced expression and activity of sPLA2-IIA via interacting with FXa receptor (effective cell protease receptor-1, EPR-1). And FXa suppressed the activation of cytosolic phospholipase A2 (cPLA2) and extracellular signal-regulated kinase (ERK) 1/2 by LPS. Therefore, these results suggest that FXa may inhibit LPS-mediated expression of sPLA2-IIA by suppression of cPLA2 and ERK 1/2.

Inhibitory effect of polyozellin on secretory group IIA phospholipase A2

The expression of secretory group IIA phospholipase A2 (sPLA2-IIA) is enhanced by development of inflammatory disorders. In this study, sPLA2-IIA expression was induced in the lipopolysaccharide (LPS)-stimulated human umbilical vein endothelial cells and mice to evaluate the effect of polyozellin. Polyozellin, a major constituent of a Korea edible mushroom Polyozellus multiplex, has been known to exhibit the biological activities such as anti-oxidative and anti-inflammatory effects. Polyozellin remarkably suppressed the LPS-mediated protein expression and activity of sPLA2-IIA via inhibition of phosphorylation of cytosolic phospholipase A2 and extracellular signal-regulated kinase 1/2. These results demonstrated that polyozellin might play an important role in the modulation of sPLA2-IIA expression and activity in response to the inflammatory diseases.

Novel insight into drug repositioning: Methylthiouracil as a case in point

Drug repositioning refers to the development of existing drugs for new indications. These drugs may have (I) failed to show efficacy in late stage clinical trials without safety issues; (II) stalled in the development for commercial reasons; (III) passed the point of patent expiry; or (IV) are being explored in new geographic markets. Over the past decade, pressure on the pharmaceutical industry caused by the 'innovation gap' owing to rising development costs and stagnant product output have become major reasons for the growing interest in drug repositioning. Companies that offer a variety of broad platforms for identifying new indications have emerged; some have been successful in building their own pipelines of candidates with reduced risks and timelines associated with further clinical development. The business models and platforms offered by these companies will be validated if they are able to generate positive proof-of-concept clinical data for their repositioned compounds. This review describes the strategy of biomarker-guided repositioning of chemotherapeutic drugs for inflammation therapy, considering the repositioning of methylthiouracil (MTU), an antithyroid drug, as a potential anti-inflammatory reagent.

Glycyrrhetinic acid prevents cutaneous scratching behavior in mice elicited by substance P or PAR-2 agonist

Although glycyrrhetinic acid (GA) has been used for the prevention of itch in chronic dermatitis, the mechanism underlying the antipruritic effects of GA is still unclear. Recently, several mediators other than histamine, such as substance P and tryptase, were found to participate in chronic itch. Here, we investigated the effect of GA on pruritus induced by various pruritic agents including histamine in mice. We also determined the level of leukotriene (LT)B(4) in mouse skin injected with substance P in an effort to uncover part of the antipruritic mechanism of GA. Scratching events were counted for 10 min after intradermal injection of histamine, substance P (100 nmol per site each), protease-activated receptor-2 (PAR-2) agonistic peptide (50 nmol per site), or LTB(4) (0.03 nmol per site) with or without GA (4 nmol per site) into male ICR mice. Levels of LTB(4) in the skin after injection of substance P were determined by ELISA. GA did not suppress scratching behavior induced by histamine and LTB(4), but markedly and dose-dependently suppressed that induced by substance P and PAR-2 agonistic peptide. LTB(4) levels in skin elevated by substance P were lowered by GA. These data support the efficacy of GA in counteracting itch in chronic dermatitis because GA reduced scratching behavior induced by substance P and PAR-2 agonistic peptide. GA may exert antipruritic effects via inhibition of LTB(4) production in skin.

Viusid, a nutritional supplement, increases survival and reduces disease progression in HCV-related decompensated cirrhosis: a randomised and controlled trial

OBJECTIVES

Viusid is a nutritional supplement with recognised antioxidant and immunomodulatory properties which could have beneficial effects on cirrhosis-related clinical outcomes such as survival, disease progression and development of hepatocellular carcinoma (HCC). This study evaluated the efficacy and safety of viusid in patients with HCV-related decompensated cirrhosis.

DESIGN

A randomised double-blind and placebo-controlled study was conducted in a tertiary care academic centre (National Institute of Gastroenterology, Havana, Cuba). The authors randomly assigned 100 patients with HCV-related decompensated cirrhosis to receive viusid (three oral sachets daily, n=50) or placebo (n=50) during 96 weeks. The primary outcome of the study was overall survival at 96 weeks, and the secondary outcomes included time to disease progression, time to HCC diagnosis, time to worsening of the prognostic scoring systems Child-Pugh and Model for End-Stage Liver Disease, and time to a new occurrence or relapse for each one of the main clinical complications secondary to portal hypertension at 96 weeks.

RESULTS

Viusid led to a significant improvement in overall survival (90%) versus placebo (74%) (HR 0.27, 95% CI 0.08 to 0.92; p=0.036). A similar improvement in disease progression was seen in viusid-treated patients (28%), compared with placebo-treated patients (48%) (HR 0.47, 95% CI 0.22 to 0.89; p=0.044). However, the beneficial effects of viusid were wholly observed among patients with Child-Pugh classes B or C, but not among patients with Child-Pugh class A. The cumulative incidence of HCC was significantly reduced in patients treated with viusid (2%) as compared with placebo (12%) (HR 0.15, 95% CI 0.019 to 0.90; p=0.046). Viusid was well tolerated.

CONCLUSIONS

The results indicate that treatment with viusid leads to a notable improvement in overall clinical outcomes such as survival, disease progression and development of HCC in patients with HCV-related decompensated cirrhosis. Trial registration number http://ClinicalTrials.gov (NCT00502086).

Exosomes account for vesicle-mediated transcellular transport of activatable phospholipases and prostaglandins

Exosomes are bioactive vesicles released from multivesicular bodies (MVB) by intact cells and participate in intercellular signaling. We investigated the presence of lipid-related proteins and bioactive lipids in RBL-2H3 exosomes. Besides a phospholipid scramblase and a fatty acid binding protein, the exosomes contained the whole set of phospholipases (A2, C, and D) together with interacting proteins such as aldolase A and Hsp 70. They also contained the phospholipase D (PLD) / phosphatidate phosphatase 1 (PAP1) pathway leading to the formation of diglycerides. RBL-2H3 exosomes also carried members of the three phospholipase A2 classes: the calcium-dependent cPLA(2)-IVA, the calcium-independent iPLA(2)-VIA, and the secreted sPLA(2)-IIA and V. Remarkably, almost all members of the Ras GTPase superfamily were present, and incubation of exosomes with GTPgammaS triggered activation of phospholipase A(2) (PLA(2))and PLD(2). A large panel of free fatty acids, including arachidonic acid (AA) and derivatives such as prostaglandin E(2) (PGE(2)) and 15-deoxy-Delta(12,14)-prostaglandinJ(2) (15-d PGJ(2)), were detected. We observed that the exosomes were internalized by resting and activated RBL cells and that they accumulated in an endosomal compartment. Endosomal concentrations were in the micromolar range for prostaglandins; i.e., concentrations able to trigger prostaglandin-dependent biological responses. Therefore exosomes are carriers of GTP-activatable phospholipases and lipid mediators from cell to cell.

Electrospray ionization mass spectrometry as a critical tool for revealing new properties of snake venom phospholipase A2

Results from high-performance liquid chromatography/nano-electrospray ionization tandem mass spectrometry (HPLC/nESI-MS/MS) coupled to two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (2D SDS-PAGE) indicated that the monomer and dimer of phospholipase A(2) (PLA(2)) coexisted in crude Chinese Agkistrodon blomhoffii Ussurensis snake venom (ABUSV). Then, an acidic PLA(2) with the accurate molecular mass of 13979.6 Da was purified from ABUSV (mo-ABUSV-aPLA(2)). MS/MS-derived peptides from ABUSV-aPLA(2) were compared with other homologous snake venom PLA(2)s, which in turn showed that ABUSV-aPLA(2) is a novel snake venom PLA(2). Meanwhile, the ABUSV-aPLA(2) dimer (di-ABUSV-aPLA(2)) was also obtained. MS/MS analysis identified the same peptides from di-ABUSV-aPLA(2) as from mo-ABUSV-aPLA(2), which indicates that di-ABUSV-aPLA(2) is a homodimer. One Ca(2+) ion is contained per ABUSV-aPLA(2). The Ca(2+) ion is critical for both the hydrolytic activity and the structure of ABUSV-aPLA(2). Pro-Q Emerald and Pro-Q Diamond specific glycoprotein and phosphoprotein staining combined with MS/MS analysis indicated that the ABUSV-aPLA(2) is both a glycoprotein and a phosphoprotein, which to our knowledge is the first such report for a snake venom PLA(2) and thus provides new threads for the study of the functions and structures of snake venom PLA(2)s. One phosphorylation site and the size of the glycan chain are determined by using HPLC/nESI-MS/MS and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS. The delicate utilization of ESI-MS can exert tremendous impact on protein sciences.

Effects of hyaluronan treatment on lipopolysaccharide-challenged fibroblast-like synovial cells

Numerous investigations have reported the efficacy of exogenous hyaluronan (HA) in modulating acute and chronic inflammation. The current study was performed to determine the in vitro effects of lower and higher molecular weight HA on lipopolysaccharide (LPS)-challenged fibroblast-like synovial cells. Normal synovial fibroblasts were cultured in triplicate to one of four groups: group 1, unchallenged; group 2, LPS-challenged (20 ng/ml); group 3, LPS-challenged following preteatment and sustained treatment with lower molecular weight HA; and group 4, LPS-challenged following pretreatment and sustained treatment with higher molecular weight HA. The response to LPS challenge and the influence of HA were compared among the four groups using cellular morphology scoring, cell number, cell viability, prostaglandin E2 (PGE2) production, IL-6 production, matrix metalloproteinase 3 (MMP3) production, and gene expression microarray analysis. As expected, our results demonstrated that LPS challenge induced a loss of characteristic fibroblast-like synovial cell culture morphology (P < 0.05), decreased the cell number (P < 0.05), increased PGE2 production 1,000-fold (P < 0.05), increased IL-6 production 15-fold (P < 0.05), increased MMP3 production threefold (P < 0.05), and generated a profile of gene expression changes typical of LPS (P < 0.005). Importantly, LPS exposure at this concentration did not alter the cell viability. Higher molecular weight HA decreased the morphologic change (P < 0.05) associated with LPS exposure. Both lower and higher molecular weight HA significantly altered a similar set of 21 probe sets (P < 0.005), which represented decreased expression of inflammatory genes (PGE2, IL-6) and catabolic genes (MMP3) and represented increased expression of anti-inflammatory and anabolic genes. The molecular weight of the HA product did not affect the cell number, the cell viability or the PGE2, IL-6, or MMP3 production. Taken together, the anti-inflammatory and anticatabolic gene expression profiles of fibroblast-like synovial cells treated with HA and subsequently challenged with LPS support the pharmacologic benefits of treatment with HA regardless of molecular weight. The higher molecular weight HA product provided a cellular protective effect not seen with the lower molecular weight HA product.

Viusid, a nutritional supplement, in combination with interferon alpha-2b and ribavirin in patients with chronic hepatitis C

BACKGROUND

The pathogenesis of chronic hepatitis C (CHC) is associated to severe oxidative stress that leads to necro-inflammation and progression of fibrosis. Previous trials suggested that antioxidative therapy may have a beneficial effect. We evaluated the efficacy and safety of Viusid in combination with interferon alpha-2b (IFN alpha-2b) and ribavirin in patients with CHC.

METHODS

We randomly assigned 100 patients, between October 2002 and December 2004, in two arms: IFN alpha-2b (5 MU on alternate days), ribavirin at a dose of 13 mg/kg daily and Viusid (three sachets daily) vs. IFN alpha-2b (5 MU on alternate days) and ribavirin at a dose of 13 mg/kg daily. Subjects were treated for 48 weeks and then followed for an additional 24 weeks. The primary end point was the histologic response (reduction of at least two points without fibrosis worsening in the total score on the Histological Activity Index).

RESULTS

A significantly high proportion of patients who received combined therapy plus Viusid had a histologic response better than those patients who received IFN alpha-2b and ribavirin (57% vs. 37%, P=0.03). The patients with virologic response achieved the highest percentages of histologic response, irrespective of assigned treatment. Among non-responders, the highest reduction in the mean change from baseline score for necro-inflammatory activity (NA) and fibrosis (F) was reported in patients treated with Viusid [NA, -1.50 (Viusid), -1.20 (without Viusid); F, -0.31 (Viusid), 0.00 (without Viusid)]. Sustained normalization of serum alanine aminotransferase concentration was highest in the Viusid group compared with standard therapy (67% vs. 41%, P=0.009). The overall safety profile was similar in both groups, but interestingly, the anemia was less intense in the group with Viusid (P=0.04).

CONCLUSIONS

Our results suggest that triple therapy with Viusid, IFN alpha-2b and ribavirin was well tolerated and may have a beneficial effect on histologic and biochemical variables. The intensity of anemia is reduced in patients treated with Viusid.

Phospholipase A(2) activity of beta-bungarotoxin is essential for induction of cytotoxicity on cerebellar granule neurons

The aim of this study was to investigate the mechanism of the cytotoxic effect of beta-bungarotoxin (beta-BuTX), a presynaptic neurotoxin, on rat cerebellar granule neurons (CGNs). The maturation of CGNs is characterized by the prominent dense neurite networks that became fragmented after treatment with beta-BuTX, and this cytotoxic effect of beta-BuTX on CGNs was in a dose- and time-dependant manner. The cytotoxic effect of beta-BuTX was found to be more potent than other toxins, such as alpha-BuTX, cardiotoxin, melittin, and Naja naja atra venom phospholipase A(2). Meanwhile, undifferentiated neuroblastoma neuronal cell lines, IMR-32 and SK-N-MC, and astrocytes were found to be resistant to beta-BuTX. These results indicated that only the mature CGNs were sensitive to beta-BuTX insults. None of the following chemicals: antioxidants, K(+)-channel activator, K(+)-channel antagonists, intracellular Ca(2+) chelator, Ca(2+)-channel blockers, NMDA receptor antagonists, and nitric oxide synthase inhibitor tested, were able to reduce beta-BuTX-induced cytotoxicity. However, secretory type phospholipase A(2) inhibitors (glycyrrhizin and aristolochic acid) and a free radical scavenger (5,5-dimethyl pyrroline N-oxide, DMPO) could attenuate not only beta-BuTX-induced cytotoxicity but also ROS production and caspase-3 activation. These data suggest that phospholipase A(2) activity of beta-BuTX may be responsible for free radical generation and caspase-3 activation that accounts for the observed cytotoxic effect. It is proposed that the CGNs can be a useful tool for studying interactions of the molecules on neuronal plasma membrane with beta-BuTX that mediates the specific cytotoxicity.

Biochemical characterization of an effective substrate and potent activators of CK2 copurified with Bowman-Birk-type proteinase inhibitor from soybean seeds in vitro

By means of Mono P column chromatography, an effective phosphate acceptor (EPA) of casein kinase 2 (CK2) was purified from the Bowman-Birk-type proteinase inhibitor (BBI) fraction of soybean seeds. The most acidic EPA (aEPA, pI=approx. 3.7) was heavily phosphorylated when incubated with CK2 and 5 microM [gamma-(32)P]ATP in the presence of poly-Arg (a CK2 activator) in vitro. However, aEPA was slightly phosphorylated by casein kinase 1 (CK1) as effective as C-kinase and not at all by A-kinase in vitro. The 13 N-terminal amino acid residues (SDHSSSDDESSKP) of aEPA were 100% homologous to the corresponding sequence of soybean BBI-type proteinase inhibitor CII (SBI CII). Polyamine at 3 mM stimulated 4.6-fold the CK2-mediated phosphorylation of aEPA, and this phosphorylation was sensitive to quercetin (ID(50)=approx. 0.1 microM) in vitro. Furthermore, two basic proteins [Mr=29,000 (p29) and 17,000 (p17)] copurified with BBI were identified as proteolytic cleavage products of basic 7S globulin and functioned as potent CK2 activators in vitro. aEPA fully phosphorylated by CK2 in the presence of poly-Arg or basic proteins formed a complex with trypsin, whereas unphosphorylated aEPA was digested by trypsin in vitro. These results suggest that (i) aEPA (a BBI isoform) may coexist with two basic proteins (p29 and p17) generated from basic 7S globulin; and (ii) the physiological interaction between aEPA and its binding trypsin-like proteinases may be regulated through specific phosphorylation of aEPA by CK2 activated with the two basic proteins in legume seeds.

Casein kinase 2 (CK2)-mediated reduction of the activities of Src family tyrosine kinases in vitro

The physiological correlation between casein kinase 2 (CK2) and two Src family tyrosine kinases (Src-TKs, Fyn and Src) was mainly investigated in vitro. It was found that (i) Thr-residues of these two Src-TKs were preferentially phosphorylated by CK2 using [gamma-32P]GTP as a phosphate donor; (ii) this phosphorylation was highly stimulated in the presence of poly-Arg; (iii) full phosphorylation of two Src-TKs by CK2 resulted in significant reduction of their TK activities; and (iv) quercetin (a CK2 inhibitor) inhibited the CK2-mediated reduction of their Src-TK activities in vitro. Under the same experimental conditions, similar results were obtained with Yes. These results suggest that CK2 may be a protein kinase responsible for the suppression of at least three Src-TKs (Fyn, Src and Yes) through the specific phosphorylation of their Thr-residues at the cellular level.

Licochalcone-A, a novel flavonoid isolated from licorice root (Glycyrrhiza glabra), causes G2 and late-G1 arrests in androgen-independent PC-3 prostate cancer cells

Licochalcone (LA) is a novel estrogenic flavonoid isolated from PC-SPES composition herb licorice root that was reported to show significant antitumor activity in various malignant human cell lines. To better understand its anti-CaP activities, we have investigated LA-elicited growth control and induction of apoptosis using androgen-independent p53-null PC-3 prostate cancer cells. LA induced modest level of apoptosis but had more pronounced effect on cell cycle progression arresting cells in G2/M, accompanied by suppression of cyclin B1 and cdc2. It also inhibited phosphorylation of Rb, specifically phosphorylation of S780 with no change of phosphorylation status of T821, decreased expression of transcription factor E2F concurrent with reduction of cyclin D1, down-regulation of CDKs 4 and 6, but increased cyclin E expression. These findings provide mechanistic explanation for LA activity and suggest that it may be considered as a chemopreventive agent and its anticancer properties should be further explored.

Up-regulating effects of glycyrrhizin on interleukin-18 gene expression by cDNA microarray

AIM: To investigate the relationship of glycyrrhizin and interleukin 18 (IL-18) gene expression and to explore the molecular biological mechanisms of glycyrrhizin in antivirus functions.

METHODS: cDNA microarray was used for the study of up-regulated gene by glycyrrhizin. Polymerase chain reaction (PCR) technique was employed to amplify the sequence of IL-18 promoter by using HepG2 cell genomic DNA as the template, named IL-18P, and the PCR product was cloned into pGEM-T vector. The IL-18P gene was cut from T-IL-18 P by KpnI and Bgl II, and then cloned into pCAT3 basic, named pCAT3- IL-18P. pCAT3-IL-18P was transfected into the HepG2 cell line and cotransfected HepG2 cells with glycyrrhizin by FuGENE 6 transfection reagents. The HepG2 cells transfected with pCAT3-basic was used as negative control. The activity of chloramphenicol acetyltransferase (CAT) in HepG2 cells transfected was detected by an enzyme-linked immunoassay (ELISA) kit after 48 h, which reflected the transactivating function of glycyrrhizin to IL-18 gene promoter.

RESULTS: The expressive vector pCAT3-IL-18P was constructed and confirmed by restriction enzyme digestion and sequencing. The expression of CAT in HepG2 cells transfected with pCAT3-IL-18P and stimulated with HepG2 was 7.7 times as higher as that of pCAT3-basic, and 1.5 times as higher as that of pCAT3-IL-18P.

CONCLUSION: HepG2 can up-regulate IL-18 gene promoter. These results provide a new evidence to explain the molecular biological mechanisms of HepG2 in immuno-regulation and antivirus.

Phospholipase A2, hydroxyl radicals, and lipid peroxidation in transient cerebral ischemia

Phospholipid degradation is an important promoter of neuronal death after transient cerebral ischemia. Phospholipid hydrolysis by phospholipase A2 (PLA2) after transient cerebral ischemia releases arachidonic acid. Arachidonic acid metabolism results in formation of reactive oxygen species, lipid peroxides, and toxic aldehydes (malondialdehyde, 4-hydroxynonenal, and acrolein). Citicoline (cytidine-5'-diphosphocholine), an intermediate in phosphatidylcholine synthesis, has undergone 13 phase III clinical trials for stroke, and is being evaluated for treatment of Alzheimer's and Parkinson's diseases. Here we examined the effect of citicoline on PLA2 activity in relationship to attenuating hydroxyl radical (OH*) generation and lipid peroxidation after transient forebrain ischemia in gerbil. High Ca2+ dependency (millimolar range) of PLA2 activity suggests that secretory PLA2 is the predominant isoform in membrane and mitochondria. Citicoline attenuated the increase in PLA2 activity in both membrane and mitochondrial fractions. In vitro, citicoline and its components choline and cytidine had no effect on the PLA2 activity. Thus, citicoline is not a "direct PLA2 inhibitor." Citicoline also significantly attenuated loss of cardiolipin and arachidonic acid release from phosphatidylcholine and phosphatidylethanolamine. Transient cerebral ischemia resulted in significant formation of OH* and malondialdehyde, and citicoline significantly attenuated their formation. These results suggest that citicoline provides neuroprotection by attenuating the stimulation of PLA2.

Anti-inflammatory effects of intramammary infusions of glycyrrhizin in lactating cows with mastitis caused by coagulase-negative staphylococci

OBJECTIVE

To determine the anti-inflammatory effects of glycyrrhizin (GL) in lactating cows with mastitis attributable to naturally occurring infection with coagulase-negative staphylococci (CNS).

ANIMALS

12 lactating Holstein cows with mastitis attributable to infection with CNS and 2 healthy cows without mastitis.

PROCEDURE

Clinical signs, number of bacteria in milk, somatic cell count (SCC) in milk, concentrations of alpha-lactalbumin and lactoferrin in milk, and concentration of histamine in milk were investigated before and after intramammary infusion of GL (6 cows) or antimicrobials (6 cows). Glands of 2 healthy cows were infused with staphylococcal enterotoxin; milk leukocytes were then harvested and incubated with various doses of GL.

RESULTS

In cows infected with CNS that had a low bacterial concentration in milk, infusion of GL alone resulted in significant improvements in swelling, firmness of glands, and number of clots in milk, and it decreased the SCC, but not significantly. Percentage of neutrophils decreased significantly (to < 30%) by 2 days after infusion. Use of lactoferrin as a marker of inflammation in mammary glands revealed a decrease in concentrations, whereas use of alpha-lactalbumin as a marker of recovery for mammary glands revealed significant increases in concentrations in the GL-infused group. Accompanying these anti-inflammatory effects, a decrease in the concentration of histamine in milk was observed in the GL-infused group. Glycyrrhizin decreased histamine production by milk leukocytes in a concentration-dependent manner.

CONCLUSIONS AND CLINICAL RELEVANCE

Infusion of GL may regulate intramammary inflammation through modulation of inflammatory mediators such as histamine.

A novel CK2-mediated activation of type II cAMP-dependent protein kinase through specific phosphorylation of its regulatory subunit (RIIα) in vitro

The physiological significance of the casein kinase 2 (CK2)-mediated phosphorylation of type II cAMP-dependent protein kinase (PKAIIalpha) and free type II regulatory (R) subunit (RIIalpha) on their activities was mainly investigated in vitro. In these experiments, [gamma-32P]GTP was used as a phosphate donor for the CK2-mediated phosphorylation of free RIIalpha and PKAIIalpha (bovine heart) in vitro. It was found that: (i). CK2 phosphorylated only threonine (Thr)-residues of free RIIalpha and phosphorylated preferentially Thr-residues of the R subunit (RIIalpha) of PKAIIalpha (PKA RIIalpha) in vitro; (ii). this phosphorylation was selectively inhibited by quercetin (an CK2 inhibitor); and (iii). the phosphorylation of free RIIalpha by CK2 resulted in the reduction of its suppressive effect on the activity (phosphorylation of histone H2B) of the catalytic (C) subunit and in the reduction of its ability to form a complex with the C subunit in vitro. As expected, the activity of PKAIIalpha was approx. 3.5-fold enhanced after its R subunit was fully phosphorylated by CK2 in vitro. cAMP synergistically stimulated the activity of PKAIIalpha phosphorylated by CK2 in vitro. These results strongly suggest that CK2 may be a protein kinase responsible for the activation of PKAIIalpha through specific phosphorylation of its R subunit at the cellular level.

Citicoline decreases phospholipase A2 stimulation and hydroxyl radical generation in transient cerebral ischemia

Neuroprotection by citicoline (CDP-choline) in transient cerebral ischemia has been demonstrated previously. Citicoline has undergone several Phase III clinical trials for stroke, and is being evaluated for treatment of Alzheimer's and Parkinson's diseases. Phospholipid degradation and generation of reactive oxygen species (ROS) are major factors causing neuronal injury in CNS trauma and neurodegenerative diseases. Oxidative metabolism of arachidonic acid (released by the action of phospholipases) contributes to ROS generation. We examined the effect of citicoline on phospholipase A(2) (PLA(2)) activity in relation to the attenuation of hydroxyl radical (OH.) generation after transient forebrain ischemia of gerbil. PLA(2) activity (requires mM Ca(2+)) increased significantly (P < 0.05) in both membrane (50.2 +/- 2.2 pmol/min/mg protein compared to sham 35.9 +/- 3.2) and mitochondrial fractions (77.0 +/- 1.2 pmol/min/mg protein compared to sham 33.9 +/- 1.2) after cerebral ischemia and 2 hr reperfusion in gerbil, which was significantly attenuated (P < 0.01) by citicoline (membrane, 39.9. +/- 2.2 and mitochondria, 41.9 +/- 3.2 pmol/min/mg protein). In vitro, citicoline and its components cytidine and choline had no effect on PLA(2) activity, and thus citicoline as such is not a PLA(2) inhibitor. Ischemia/reperfusion resulted in significant OH. generation (P < 0.01) and citicoline significantly (P < 0.01) attenuated their formation (expressed as 2,3-dihydroxybenzoic acid/salicylate ratio; ischemia/24 hr reperfusion, 6.30 +/- 0.23; sham, 2.56 +/- 0.27; ischemia/24 hr reperfusion + citicoline, 4.85 +/- 0.35). These results suggest that citicoline affects PLA(2) stimulation and decreases OH. generation after transient cerebral ischemia.

Was it there all the time?

The complement system is old, yet it may still have something new to teach us. For many years, research has existed which shows that C3d, in addition to its established role as an adjuvant, could have an immunosuppressive activity. Being true, it suggests that a common mechanism may be used both by organisms and by their pathogens to prevent unwanted immune responses.