Competition between TRAF2 and TRAF6 Regulates NF-κB Activation in Human B Lymphocytes

Objective To investigate the role of TNF receptor-associated factor 2 (TRAF-2) and TRAF6 in CD40-induced nuclear factor-κB (NF-κB) signaling pathway and whether CD40 signaling requires TRAF2. Methods Human B cell lines were transfected with plasmids expressing wild type TRAF2 or dominant negative TRAF2,TRAF2-shRNA,or TRAF6-shRNA. The activation of NF-κB was detected by Western blot,kinase assay,transfactor enzyme-linked immunosorbent assay (ELISA),and fluorescence resonance energy transfer (FRET). Analysis of the role of TRAF-2 and TRAF-6 in CD40-mediated NF-κB activity was examined following stimulation with recombinant CD154. Results TRAF2 induced activity of IκB-kinases (IKKα,IKKi/ε),phosphorylation of IκBα,as well as nuclear translocation and phosphorylation of p65/RelA. In contrast,TRAF6 strongly induced NF-κB activation and nuclear translocation of p65 as well as p50 and c-Rel. Engagement of CD154-induced nuclear translocation of p65 was inhibited by a TRAF6-shRNA,but conversely was enhanced by a TRAF2-shRNA. Examination of direct interactions between CD40 and TRAFs by FRET documented that both TRAF2 and TRAF6 directly interacted with CD40. However,the two TRAFs competed for CD40 binding. Conclusions These results indicate that TRAF2 can signal in human B cells,but it is not essential for CD40-mediated NF-κB activation. Moreover,TRAF2 can compete with TRAF6 for CD40 binding,and thereby limit the capacity of CD40 engagement to induce NF-κB activation.

Detection of CYP2E1,a Genetic Biomarker of Susceptibility to Benzene Metabolism Toxicity in Immortal Human Lymphocytes Derived from the Han Chinese Population

Objective Cytochrome P450 2E1 （CYP2E1） is an important metabolizing enzyme involved in oxidative stress responses to benzene, a chemical associated with bone marrow toxicity and leukemia, We aimed to identify the CYP2E1 genetic biomarkers of susceptibility to benzene toxicity in support of environmental and occupational exposure prevention, and to test whether a model using immortal human lymphocytes might be an efficient tool for detecting genetic biomarkers. Methods Immortalized human lymphocyte cell lines with independent genotypes on four CYP2E1 SNP sites were induced with 0.01% phenol, a metabolite of benzene. CYP2E1 gene function was evaluated by mRNA expression and enzyme activity. DNA damage was measured by Single-Cell Gel Electrophoresis （SCGE）. Results Among the four SNPs, cells with rs2070673TT and rs2030920CC showed higher levels of ~YP2E1 transcription and enzymatic activity than the other genotypes in the same SNP site. Cells with higher gene expression genotypes also showed higher comet rates compared with lower gene expression genotypes. Conclusion These results suggest that CYP2E1 rs2070673 and rs2030920 might be the genetic biomarkers of susceptibility to benzene toxicity and that the immortalized human lymphocytes model might be an efficient tool for the detection of genetic biomarkers of susceptibility to chemicals.

Genotoxicity evaluation of drinking water sources in human peripheral blood lymphocytes using the comet assay

The potential harm of organic pollutants in drinking water to human health is widely focused on in the wodd; more and more pollutants with genotoxic substances are released into the aquatic environment. Water source samples were collected from 7 different localities of Nanjing City. The potential genotoxicity of organic extracts from drinking water sources were investigated by means of the comet assay in human peripheral lymphocytes. The results showed that all the organic extracts from all the water source samples could induce DNA damages of human peripheral blood lymphocytes at different levels. A significant difference （P 〈 0.01） was observed when compared with the solvent control, The DNA damage increased with the increase of the dosage of the original water source. Significant differences of DNA damage were observed in different drinking water sources, as shown by the multiple comparisons analysis at the dosage of 100x; the degree of DNA damage treated by Hushu waterworks （at town level） was the most serious, the arbitrary units （AU） was 141.62±6.96, however, that of Shangyuanmen waterworks （at city level） was only 109.64±2.97. The analysis also revealed that the genotoxicity of town＇s water sources was higher than that of the city. The results demonstrated that the comet assay can be successfully applied to the genotoxicity monitoring programs of drinking water sources.

Metallothionein 1 Isoform Gene Expression Induced by Cadmium in Human Peripheral Blood Lymphocytes

Objective To study the gene expression of metallothionein 1 （MT-1） isoforms in human peripheral blood lymphocytes （HPBLs）. Methods The expression of mRNA representing the seven active MT-I genes was determined in HPBLs by quantitative RT-PCR before and after exposure to cadmium. Results Basal expressions of MT-IX, and MT-1A in HPBLs were similar to expression of housekeeping gene. In contrast, the basal gene expressions of MT- 1 H, IF, 1E, and 1G were a little transcripts in human HPBLs. No signal was detected for MT-1B. There was a sex difference （P〈0.05）. in basal gene expression of MT-1E. The levels of gene expression of MT-1A, 1E, IF, 1G, 1H, and 1X increased, but the level of MT-1B did not increase after exposure to cadmium. Conclusions Gene expressions of MT-1 G, MT-1 H, MT-1 F, and MT-1X in HPBLs can be used as a potential biomarker of cadmium exposure.

CHANGES IN ACTIVITY OF INSULIN RECEPTOR TYROSINE KINASE AND CHARACTERISTICS OF ITS ENDOGENOUS SUBSTRATE IN TRANSFORMED HUMAN LYMPHOCYTES

The cascade reaction of tyrosine phosphorylation provides an attractive mechanism to regulate the metabolism and growth of normal and transformed cells. Thus, considerable effort has been made to identify the cellular substrates of the tyrosine kinases. In this work, the activity of the Insulin receptor tyrosine kinase and endogenous substrate in transformed lymphocytes were studied. Purified human T lymphocytes incubated with phytohemagglutinin (PHA) for 72 hours served as transformed cells, when labeled with [32P] - orthophosphate it appeared that the insulin-dependent protein kinase activity in the transformed cells increased 9- fold. In search for the physiologically significant substrates by using polyclonal antiphosphotyrosine antibody to immunoprecipitate phosphotyrosine-containing proteins that produced in the intact cell during insulin stimulation, a protein with molecular weight of 45kDa as identified and designated as PP45, which occurred during the 5 minutes response of lymphocytes to insulin.

IN VITRO ANTITUMOR ACTIVITY OF TUMOR-INFILTRATING LYMPHOCYTES FROM HUMAN GASTRIC CARCINOMA

Tumor-infiltrating lymphocytes (TIL) isolated from 11 gastric carcinoma were studied. TIL could grow for a long-term in medium containing recombi-nant interleukin-2(rlL-2). The mean expansion fold achieved in 6 long-term cultures of 11 specimens was 15.1. RIL-2 expanded gastric TIL exhibited significant cytotoxicity against K562, BGC823, MCF-7 and more effective antitumor cytotoxicity against fresh autologous tumor targets and human gastric cancer cell line. Peak cytotoxicity was shown in the third or fourth week after cultures. Cryopreservation of gastric TIL didn't influence their expansion capacity and antitumor activity. Phenotypic analysis was demonstrated in this study. The results of present study indicate that TIL from human gastric carcinoma could be expanded and reach high levels of antitumor effector function in long-term cultures with rIL-2. Their function may be of clinical importance.

Human papilloma virus 16 E6 oncoprotein associated with p53 inactivation in colorectal cancer

AIM:To investigate the association between human papilloma virus(HPV) infection and colorectal cancer.METHODS:Sixty-nine patients with pathologically confirmed primary colorectal cancer including 6 stage Ⅰ,24 stage Ⅱ,21 stage Ⅲ,and 18 stage Ⅳ patients were enrolled in this study to investigate whether HPV 16 could be involved in colorectal tumorigenesis.Nested-polymerase chain reaction(nested-PCR) was used to detect HPV16 DNA in colorectal tumor tissues and further confirmed by in situ hybridization(ISH).In addition,immunohistochemistry analysis was performed to examine the E6 oncoprotein in colorectal tumors.To verify whether E6 could inactivate the p53 transcriptional function,the levels of p21 and Mdm2 mRNA expression were evaluated by real-time reverse transcription(RT)-PCR.RESULTS:Of the 69 colorectal tumors,HPV16 DNA was detected in 11(16%) by nested-PCR,and HPV16 DNA was present in 8 of the 11(73%) tumors which was confirmed by ISH.The presence of HPV16 DNA in colorectal tumors was not associated with patients' clinical parameters including age,gender,smoking status,tumor site;however,HPV16 infection was more common in stage Ⅰ patients than in late-stages patients(Ⅱ,Ⅲ and Ⅳ).We next asked whether HPV16 infection could be linked with colorectal cancer development.Immunohistochemical data indicated that 8 of the 11 HPV16 DNA-positive tumors had E6 oncoprotein expression.Moreover,we also observed that the adjacent normal tissues including endothelial cells,lymphocytes,fibroblasts,and gland cells in E6-positive tumors had E6 oncoprotein expression.In addition,3 of the 4(75%) E6-positive tumors carrying p53 wild-type had negative immunostaining,but one tumor had less p53 immunostaining.We further examined whether E6-positive and/or p53 mutated tumors reduce p53 transcriptional activity.Real-time RT-PCR analysis indicated that p21 and mdm2 mRNA expression levels in E6/p53-wildtype tumors were significantly lower than in their adjacent normal tissues;as expected,E6-positive/p53-mutated tumors had lower p21 and mdm2 mRNA expression levels compared with their adjacent normal tissues.These results clearly indicate that the E6 oncoprotein expressed in p53 wildtype tumors may reduce p21 and mdm2 expression via p53 inactivation.CONCLUSION:These results suggest that HPV16 infection may be involved in a subset of colorectal cancer,and we suggest that the transmission of HPV to the colon and rectum might occur through peripheral blood lymphocytes.

Nicotine protects against ulcerative colitis through regulating microRNA-124 and STAT3

OBJECTIVE Although it is generally believed that nicotine accounts for the beneficial effect of smoking on ulcerative colitis,the underlying mechanisms remain not well-understood.Our previous finding that nicotine inhibits inflammatory responses through inducing miRNA-124 prompted us to ask whether the miRNA is involved in the protective action of nicotine on UC.METHODS Mi R-124 expression in colon tissues and cells was determined by q-PCR and in situ hybridization.The effect of miR-124 on protective role of nicotine in ulcerative colitis was evaluated in DSS-treated mice and IL-6-treated Caco-2 colon epithelial cells.Expression of p-STAT3/STAT3 was detected by immunohistochemistry and Western blot analysis.RESULTS miR-124 expression is upregulated in colon tissues from patients and DSS-induced colitis.Nicotine treatment further elevated miR-124 level in colon tissues of the mice,in infiltrated lymphocytes and epithelial cells,and augmented miR-124 expression in lymphocytes isolated from human ulcerative colon tissues.Administration of nicotine also reduced weight loss,improved DAI and decreased HE score in DSS-induced colitis.Moreover,knockdown of miR-124 in vivo significantly diminished the beneficial effect of nicotine,and in vitro on IL-6-treated Caco-2 colon epithelial cells.Further analysis indicated that nicotine inhibited STAT3 activation in vivo and in IL-6-treated Caco-2 colon epithelial cells and Jurkat human T lymphocytes,in whichmiR-124 knockdown led to increased activation of STAT3.CONCLUSION These data indicated that nicotine exerts its protective action in UC through inducing miR-124 and its effect on STAT3,suggesting that the miR-124/STAT3 system is a potential target for the therapeutic intervention of UC.

Investigation of the cytotoxicity,antioxidative and immune-modulatory effects of Ligusticum porteri(Osha) root extract on human peripheral blood lymphocytes

OBJECTIVE： Ligusticum ported is a traditional Native American herb. The roots of L. ported are traditionally used in the treatment of many diseases, however, its cytotoxicity, antioxidative and immune- modulatory effects need to be investigated. In this study, we evaluated the effects of the root extract at different doses on human peripheral blood lymphocytes （PBLs）. METHODS： The lymphocytes were incubated with different concentrations of the root extracts （0, 50, 100, 200, and 400 μg/mL） and harvested every 6 h for 2 d （P〈0.05）. The protective effect of the herb against oxidative damage was determined by inducing oxidative stress with the administration of 50 μmol/L of hydrogen peroxide （H202）. RESULTS： Treatments with L. ported at 200 and 400 pg/mL increased the viability of PBLs. The deleterious effect of H2O2 was ameliorated by 400μg/mL L. ported treatment. Addition of 400 μg/mL L. ported reduced lipid peroxidation in stressed PBLs by 94% （P〈0.05）. Treatment with 400 μg/mL of L. ported resulted in a 26.4% increase of reduced glutathione levels. Activities of superoxide dismutase and catalase increased by 17.5% and 55.2% respectively, when stressed PBLs were treated with 400 μg/mL L. ported for 2 d （P〈0.05）. Treatment with 400 μg/mL L. ported increased interferon-γand interleukin-2 expressions in H2O2-challenged PBLs （P〈0.05）, however, the root extract did not cause a significant difference in interleukin-10 levels compared to the control （P〉0.05）. CONCLUSION： The findings suggest that L involving protective effects against oxidative ported might be a potential immune-modulating agent damage.

THE CORRELATIVITY ANALYSIS OF SIX METHODS OF DETECTING APOPTOSIS

The aim of this study was to compare six methods of detecting apoptosis induced by extracellular adenosine triphosphate (ATP) in human leukemic lymphocytes with purinergic P2Z receptors.These methods used were electron microscopy(EM), detection of internucleosomal DNA fragmentation by agarose gel electrophoresis, autoradiographic analysis of DNA fragmentation, in situ labeling of DNA strand breaks with fluorescein dUTP and exogenous terminal deoxynucleotidyl transferase (TUNEL), quantitation of 3 ends of DNA breaks by labeling with α 32 PdCTP(TdT assay), and quantitation of apoptotic cells with fluorescein annexin V using flow cytometry(FCA).We found EM and detection of DNA ladder pattern by agarose gel electrophoresis to be specific,but lacking in sensitivity. The combination of autoradiography and gel electrophoresis gave an increase in sensitivity of at least 50 fold although, of all the methods, the TdT assay was shown to be most sensitive. The four methods for quantifying apoptosis EM, FCA, TUNEL and TdT assay proved to be reliable and gave statistically similar results on apoptotic lymphocytes. These observations indicate it is essential to combine specific, sensitive and quantitative techniques in detecting apoptosis.

Effect of the maternal-fetal interface immunoregulation on the occurrence of intrahepatic cholestasis of pregnancy

Maternal immune tolerance of the fetus is indispensable for a healthy pregnancy. Currently, the study of the immune microenvironment of the maternal-fetal interface has been a heated topic in reproductive immunology research. More and more studies show that the immune imbalance in the maternal-fetal interface plays a very important role in the incidence of intrahepatic cholestasis of pregnancy(ICP). However, the precise etiology and mechanism of immune imbalance in the occurrence of ICP is still unknown. In order to clarify the potential immunologic mechanisms of ICP, this review summarizes the recent studies of the decidual immunology microenvironment and the potential immunologic mechanisms related to the development of ICP.