[Initial study on the discrimination of oral common Actinomycetes with metabonomics method]

OBJECTIVE

The method of metabonomics based on 1H-nuclear magnetic resonance (1H-NMR) was preliminarily applied to discriminate the oral common Actinomycetes, Actinomyces naeslundii ATCC12104 and Actinomyces israelii ATCC12102.

METHODS

Solutions of Actinomyces naeslundii and Actinomyces israelii with same density were made and cultured respectively at BHI liquid culture medium. The concentration of bacteria was determined periodically, and then the growth curves were drawn. The culture solutions in stationary phase of the two bacteria were used to test with the 1H-NMR spectroscopy respectively. The data of 1H-NMR spectroscopy results were analyzed by principal components analysis (PCA).

RESULTS

The PCA showed the obvious clustering phenomena and the points of two groups data stayed differentially together by two clusters. Therefore, the NMR-based metabolomics profiles can discriminate the two different kinds of bacteria.

CONCLUSION

The analysis technology of metabonomics is expected to be applied to rapid identification of actinomycetes.

[Preliminary study on the discrimination of putative periodontal pathogens with a metabonomics method]

OBJECTIVE

To evaluate the feasibility of identifying oral pathogenic bacteria by comparing the metabolic profiling of putative periodontal pathogens and try to find a convenient and rapid way to discriminate oral microorganisms.

METHODS

Suspensions of Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum with same density were prepared and cultured respectively at liquid BHI medium. Then the growth quantity was measured periodically through turbidimetry and the growth curves of the inoculated bacteria were completed. The culture solutions of stable growth phase were sampled and characterized by 1H-nuclear magnetic resonance 1H-NMR). The data of 1H-NMR spectroscope results were analyzed by principal components analysis (PCA).

RESULTS

The PCA showed the obvious clustering phenomena and the points of three groups differentially centralized to three clusters. Therefore, the NMR-based metabonomics profiles could discriminate the three different kinds of bacteria.

CONCLUSION

The metabonomics is a potential classable method to identify the oral pathogenic bacteria.

B7-H4 transfection prolongs beta-cell graft survival

B7-H4, a recently discovered member of B7 family, can negatively regulate T cell responses. However, it is not clear whether B7-H4 negatively function in cell transplantation. In this study we investigated the immunosuppressive effect of B7-H4 on beta-cell transplantation. An insulinoma cell line, NIT-1, transfected with B7-H4 (B7-H4-NIT) was established, and transplanted to diabetic C57BL/6 mice by intraperitoneal injection. Proliferation assay of splenocytes in vitro showed that B7-H4-NIT suppressed alloreactive T cell activation. The proportion of IFN-gamma-producing cells in recipient spleen was significantly reduced and the number of Treg cells was upregulated in B7-H4-NIT group compared to the control, EGFP-NIT. The expression of mRNA coding IFN-gamma was lower but that of IL-4 was higher in B7-H4-NIT transplanted recipients than in the control animals. The results of ELISA also revealed the same trends. Diabetic mice reached normalglycemic quickly and gained weight after transplantation of B7-H4-NIT. More importantly, the survival time for recipients transplanted with B7-H4-NIT cells was significantly longer than that with EGFP-NIT cells. These results indicate that B7-H4 transfection prolongs beta-cell graft survival.

Mechanism and optimization of pH sensing using SnO2 nanobelt field effect transistors

We report a systematic investigation about the mechanism of pH sensing using SnO2 nanobelt field effect transistors (FETs). The FETs, based on single SnO2 nanobelts, are channel-limited and with proper contact passivation; the pH sensing was conducted with sodium phosphate solutions through integrated microfluidics. The responses of the FET channel conductance to pH were measured at different gate voltages: a linear pH dependence was observed in the linear transport "on" state, while an exponential dependence was observed in the subthreshold regime. Measurements at the same pH but different ion concentrations demonstrated that the FET's pH sensitivity decreases logarithmically with the ion concentration. The effect of APTES-functionalization was evaluated by comparing the pH responses of the same device with and without the surface modification. The APTES functionalization results in a slight enhancement of the pH sensitivity and a large suppression of the noise level, leading to marked improvement in the signal-to-noise ratio. The results indicate that the pH sensing is based on a screened field-effect response of the FETs to the surface protonation/deprotonation on the nanobelt. This study provides several useful guidelines for optimizing the sensor performance for chemical and biomolecular detection.

[Effects of phlegm-dispelling and blood stasis-resolving traditional Chinese drugs on the blood pressure and cell cycle of left ventricular cardiac myocytes in hypertensive rats]

OBJECTIVE

To observe the effects of phlegm-dispelling and blood stasis-resolving traditional Chinese drugs on the cell cycle of cardiac myocytes and left ventricular reconstruction in hypertensive rats.

METHODS

Bilateral renal artery stenosis was conducted to induce hypertension in rats, which were randomly divided into hypertensive model group (n = 10), sham-operated group (n = 8), high-dose drug group (n = 11) and low-dose drug group (n = 11), with 8 normal untreated rats as the normal control group. The systolic blood pressure (SBP) was measured in the tail artery of the rats. Two months after the operation, the left ventricular mass (LVM) and LVM index (LVI) were calculated in all the rats. The cell cycle changes in the left ventricular cardiac myocytes were evaluated using flow cytometry.

RESULTS

The mean blood pressure and LVI of the hypertensive model group were significantly higher than those of the normal control (P < 0.05) and sham-operated group (P < 0.01). After treatment with preparation of the traditional Chinese drugs at either high or low dose, the mean blood pressure and LVM of the rats showed obvious reduction, and LVI was decreased significantly compared with that of the model group (P < 0.05). Compared with the hypertensive model group which showed obviously decreased cell percentage in G0/G1 phase and increased S phase cells, the treatment at both doses significantly increased the cells in G0/G1 phase (P < 0.05) and decreased the S-phase cells (P < 0.05) to levels comparable to those in the normal control and sham-operated groups (P > 0.05). The percentage of G2/M-phase cells showed no significant difference between the groups (P > 0.05).

CONCLUSION

The traditional Chinese drugs can significantly decrease blood pressure and LVI in hypertensive rats, and induce cell cycle arrest in G0/G1 phase to reverse left ventricular hypertrophy by regulating the cell cycle and inhibiting the division and proliferation of the cardiac myocytes.

[Initial study on the discrimination of oral microorganisms with a metabonomics method]

OBJECTIVE

To establish the spectra of metabolites that coued be employed in identification of oral pathogenic bacteria, and try to find a convenient and rapid way to discriminate oral microorganisms.

METHODS

Suspensions of Streptococcus mutans ATCC 25175, Streptococcus sanguis ATCC 10556 and Lactobacillus acidophilus ATCC 4356 with same density were preparecd and cultured respectively at improved TPY liquid culture medium. The growth quantity were measured periodically by a turbidimeter. And the growth curves of the inoculated bacteria were completed. The culture solutions in stationary phase of the three bacteria were tested with 1H-nuclear magnetic resonance (1H-NMR) spectroscopy respectively. The data of 1H-NMR spectroscopy results were analyzed by principal components analysis (PCA).

RESULTS

The PCA showed the obvious clustering phenomena and the points of three group differentially centralized to three clusters. Therefore, the NMR-based metabonomics profiles could discriminate the three different kinds of bacteria.

CONCLUSION

The metabonomics is a promising new technology for developing to a rapid discrimination method of oral pathogenic bacteria.

Gene delivery of indoleamine 2,3-dioxygenase prolongs cardiac allograft survival by shaping the types of T-cell responses

BACKGROUND

We investigated the hypothesis that overexpression of indoleamine 2,3-dioxygenase (IDO) by a cardiac allograft may result in a survival advantage of the allograft by creating a tolerogenic microenvironment.

METHODS

An adenoviral vector encoding for murine IDO cDNA (AdIDO) was transfected into murine allogeneic cardiac allografts, and transplantation was performed for evaluation of the effects of local AdIDO transfection on allograft survival. Intragraft IDO expression and lymphocytes infiltration were measured by immunohistochemical and histological analysis. Quantitative polymerase chain reaction assays, mixed lymphocyte reaction and flow cytometric analysis were employed to determine the expression of mRNA for Foxp3, IDO, pro-inflammatory cytokines, allogeneic T-cell proliferation and the proportion of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) from graft-infiltrating lymphocytes and splenocytes of recipients, respectively.

RESULTS

Cardiac allografts transfected with AdIDO showed a significant prolonged survival compared to the control groups. Hearts treated with AdIDO exhibited considerable up-regulation of IDO expression, whereas contained significantly reduced transcript levels for interleukin (IL)-2, interferon-gamma and IL-17. These T cells isolated from allografts pre-treated with AdIDO displayed a dramatic reduction of proliferation capacity to alloantigen stimuli and had a significant higher proportion of Tregs compared to the control, as demonstrated by an increase of Foxp3 expression in allografts pre-treated with AdIDO compared to control groups.

CONCLUSIONS

Overexpression of IDO significantly delays cardiac allograft acute rejection by shaping the types of T-cell responses elicited by alloantigen stimuli.

Chromosome instability and risk of squamous cell carcinomas of head and neck

In 895 subjects with squamous cell carcinoma of the head and neck (SCCHN) and 898 cancer-free controls matched by age, sex, and ethnicity, we validated our previous finding that mutagen sensitivity as measured by the frequency of chromatid breaks in vitro induced by benzo[a]pyrene diol epoxide (BPDE) is an independent risk factor for SCCHN. Using a previously established concentration of 4 micromol/L BPDE to treat short-term cultured primary lymphocytes for 5 hours, we evaluated chromatid breaks in 50 well-spread metaphases for each blood sample. The mean frequency of BPDE-induced chromatid breaks was significantly higher in cases than in controls in non-Hispanic Whites (P = 0.0003) but not in other ethnic groups (P = 0.549 for Hispanic Americans and 0.257 for African Americans). The odds ratio associated with risk of SCCHN for the frequency of chromatid breaks greater than median value of controls was 1.56 (95% confidence interval, 1.27-1.91) in non-Hispanic Whites (767 cases and 763 controls) after adjustment for age, sex, smoking status, and drinking status. When the quartiles of the controls were used as the cutoff values, there was a dose response between the degree of mutagen sensitivity and risk of SCCHN in non-Hispanic Whites (P(trend) = 0.0001). However, none of these associations in non-Hispanic Whites was identified in Hispanic Americans (69 cases and 70 controls) or African Americans (59 cases and 65 controls), possibly because of the small samples of these ethnic groups or ethnic difference in genetic variation, which needs to be confirmed in future studies.

Altered expression of connexin-43 and impaired capacity of gap junctional intercellular communication in prostate cancer cells

Connexin-43 (Cx43) expression in prostate cancer (PCa) cells and the potency of gap junctional intercellular communication (GJIC) in the cells were investigated, with an attempt to elucidate the reason why the so-called "bystander effect" mediated by thymidine kinase (TK) suicide gene therapy on PCa cells is not of significance and to explore the role of GJIC in PCa carcinogenesis. mRNA and protein expression of Cx43 in a PCa cell line PC-3m was detected by reverse-transcription polymerase chain reaction (RT-PCR) and strapt-avidin-biotin-enzyme complex (SABC) immunohistochemical staining, and inherent GJIC of PC-3m cells was assayed by scrape-loading and dye transfer (SLDT) assay. The expression of Cx43 in human normal and malignant prostate tissues was determined by SABC immunohistochemistry as well. It was found that Cx43 mRNA and protein expression in PC-3m cells was slightly reduced as compared with positive controls and the location of Cx43 protein was aberrant in cytoplasm rather than on membrane. Assessment of paraffin sections demonstrated that the expression of Cx43 protein in PCa cells was abnormally located and markedly diminished as compared with normal prostatic epithelial ones, displaying a negative correlation to the pathological grade (chi2=4.025, P<0.05). Additionally, capacity of inherent GJIC in PC-3m cells was disrupted, which was semi-quantified as (+) or (-). It was indicated that both down-regulated expression of Cx43 mRNA and aberrant location of Cx43 protein participated in the mechanisms leading to deficient GJIC in PC-3m cells. Lack of efficient GJIC is a molecular event, which may contribute not only to limited extent of "bystander effect", but also to initiation and progression of prostatic neoplasm.

Lack of association between HLA-A, -B and -DRB1 alleles and the development of SARS: a cohort of 95 SARS-recovered individuals in a population of Guangdong, southern China

Severe acute respiratory syndrome (SARS), caused by infection with a novel coronavirus (SARS‐CoV), was the first major novel infectious disease at the beginning of the 21st century, with China especially affected. SARS was characterized by high infectivity, morbidity and mortality, and the confined pattern of the disease spreading among the countries of South‐East and East Asia suggested the existence of susceptible factor(s) in these populations. Studies in the populations of Hong Kong and Taiwan showed an association of human leucocyte antigen (HLA) polymorphisms with the development and/or severity of SARS, respectively. The aim of the present study was to define the genotypic patterns of HLA‐A, ‐B and ‐DRB1 loci in SARS patients and a co‐resident population of Guangdong province, southern China, where the first SARS case was reported. The samples comprised 95 cases of recovered SARS patients and 403 unrelated healthy controls. HLA ‐A, ‐B and ‐DRB1 alleles were genotyped using polymerase chain reaction with sequence‐specific primers. The severity of the disease was assessed according to the history of lung infiltration, usage of assisted ventilation and occurrence of lymphocytopenia. Although the allelic frequencies of A23, A34, B60, DRB1*12 in the SARS group were slightly higher, and A33, ‐B58 and ‐B61 were lower than in the controls, no statistical significance was found when the Pc value was considered. Similarly, no association of HLA alleles with the severity of the disease was detected. Thus, variations in the major histocompatibility complex are unlikely to have contributed significantly to either the susceptibility or the severity of SARS in the population of Guangdong.

In vitro benzo[a]pyrene diol epoxide-induced DNA damage and chromosomal aberrations in primary lymphocytes, smoking, and risk of squamous cell carcinoma of the head and neck

Cigarette smoking is a major risk factor for squamous cell carcinoma of the head and neck (SCCHN), but only a fraction of those exposed to cigarette smoke develops SCCHN, suggesting variation in individual susceptibility. Tobacco smoke contains a number of carcinogens that cause various kinds of damage to DNA. In this study, we simultaneously measured benzo[a]pyrene diol epoxide-induced DNA damage and chromosomal aberrations by the comet assay and the mutagen sensitivity assay, respectively, in cultured primary lymphocytes from newly recruited 123 patients with SCCHN and 136 age- and sex-matched controls. Using the control median as the cut-off, the elevated risk of SCCHN was 2.35 (95% CI, 1.37-4.03), 2.28 (95% CI, 1.34-3.98) and 3.25 (95% CI, 1.85-5.07) for high levels of tail extension, tail length and oliver tail moment of the comet assay, respectively, and 1.75 (95% CI, 1.04-2.94) for high levels of chromosomal aberrations of the mutagen sensitivity assay. The effects of these 2 types of measurements were additive; subjects with high levels of both DNA damage and chromosomal aberrations had a 4.77-fold increased risk (95% CI, 2.73-8.36) of SCCHN. Cigarette smoking further elevated this risk to more than 20-fold (OR 23.6; 95% CI, 8.92-62.3). These data support our previous finding that suboptimal repair contributed to susceptibility to SCCHN and the new data further suggests a possible gene-environment interaction that may play an important role in the etiology of SCCHN. Further validation studies are warranted.

A limited course of soluble CD83 delays acute cellular rejection of MHC-mismatched mouse skin allografts

CD83 is a surface marker expressed on matured dendritic cells (DCs). It plays a pivotal role in the mediation of DC/T cell interaction and induction of T-cell activation. Previous studies have suggested that a soluble form of CD83 could suppress DC maturation and inhibit T-cell activation and, as a result, it can prevent paralysis associated with experimental autoimmune encephalomyelitis. Here, we explored its potential effect on allograft rejection in a fully major histocompatibility complex-mismatched murine skin transplantation model. A form of mouse soluble CD83 (CD83-Ig) fused the extracellular domain of murine CD83 with human IgG1alpha Fc tail was purified from transfected COS-7 cell. It was found that the treatment of recipient mice with CD83-Ig significantly delayed allograft rejection. Especially, when T cells originated from recipients treated with CD83-Ig re-stimulated with donor-specific splenocytes, they showed a significant reduced responding capability as compared with that of originated from control recipients. In line with these results, a reduction for serum IFN-gamma and IL-2 and a decreased mRNA expression of IFN-gamma and IL-2 in allograft infiltrated immune cells were also observed. Our results suggest that CD83-Ig could be useful for the treatment of allograft rejection in combination with other therapeutic strategies.

[Construction of HA-1-DC nucleic-acid vaccine and induction of specific cytotoxic T lymphocytes]

The purpose of this study was to construct a HA-1-DC nucleic acid vaccine and to induce anti-leukemia effect after hematopoietic stem cell transplantation (HSCT). The dendritic cells (DCs) were generated from HSCT donors in vitro, and its immunologic activity was studied by using flow cytometry and mix lymphocyte reaction. HA-1 gene was electroporated into the cultured DCs to construct a DC nucleic acid vaccine. After transfecting for 48 hours, the expression of HA-1 protein was detected by Western blot. The DCs were cultured with isogenic lymphocytes to induce specific cytotoxic T lymphocytes (CTLs). The cytotoxicity of the CTLs was detected by LDH assay. The results showed that the DCs derived from peripheral blood monocytes (PBMCs) expressed the DC phenotype, and were effective in stimulating proliferation of the allogenic lymphocytes. After electroporating for 48 hours, HA-1 protein was detected by Western blot. The cytotoxity of inducing CTLs was higher than that in the control group. It is concluded that the minor histocompatibility antigen HA-1 can be considered as a target of immunotherapy against leukemia after HSCT.

172G>T variant in the 5' untranslated region of DNA repair gene RAD51 reduces risk of squamous cell carcinoma of the head and neck and interacts with a P53 codon 72 variant

RAD51 participates in homologous recombination (HR) repair of double-stranded DNA breaks (DSBs) that may cause genomic instability and cancer. Two single-nucleotide polymorphisms (SNPs) and three P53 binding sites have been found in the RAD51 promoter and 5' untranslated region. We hypothesized that RAD51 and P53 SNPs may interact and alter risk of squamous cell carcinoma of the head and neck (SCCHN) and we genotyped for RAD51 135G>C and 172G>T and P53 Arg72Pro SNPs in 716 SCCHN patients and 719 matched controls (all non-Hispanic whites) and evaluated their effects on gamma radiation-induced mutagen sensitivity. We found that RAD51 172TT homozygotes had a significantly decreased risk [adjusted odds ratio (OR) = 0.66, 95% confidence interval (CI) = 0.50-0.87] of SCCHN, compared with carriers of other genotypes, particularly in P53 Arg72Arg homozygotes (adjusted OR = 0.60, 95% CI = 0.41-0.89) (homogeneity test P = 0.047), although no alterations in the risk were associated with the RAD51 135G>C and P53 Arg72Pro SNPs. Consistent with a protective effect of the 172TT genotype, significantly fewer gamma radiation-induced chromatid breaks per cell were present in 172TT homozygotes (mean +/- SD = 0.36 +/- 0.13) than in subjects with other genotypes (mean +/- SD = 0.46 +/- 0.13, P < 0.001) among 148 control subjects we tested. The finding that the functional RAD51 172G>T SNP, particularly in the presence of the P53 Arg72Arg genotype, may be a marker of susceptibility to SCCHN needs to be validated by larger studies of different ethnic populations.

Pretreatment with soluble ST2 reduces warm hepatic ischemia/reperfusion injury

The interleukin-1 receptor-like protein ST2 exists in both membrane-bound (ST2L) and soluble form (sST2). ST2L has been found to play an important regulatory role in Th2-type immune response, but the function of soluble form of ST2 remains to be elucidated. In this study, we report the protective effect of soluble ST2 on warm hepatic ischemia/reperfusion injury. We constructed a eukaryotic expression plasmid, psST2-Fc, which expresses functional murine soluble ST2-human IgG1 Fc (sST2-Fc) fusion protein. The liver damage after ischemia/reperfusion was significantly attenuated by the expression of this plasmid in vivo. sST2-Fc remarkably inhibited the activation of Kupffer cells and the production of proinflammatory mediators TNF-alpha and IL-6. Furthermore, the levels of TLR4 mRNA and the nuclear translocation of NF-kappaB were also suppressed by pretreatment with sST2-Fc. These results thus identified soluble ST2 as a negative regulator in hepatic I/R injury, possibly via ST2-TLR4 pathway.

Cooperative therapeutic effects of herpes simplex virus thymidine kinase gene/ganciclovir system and chemotherapeutic agents on prostate cancer in vitro

The killing effects of herpes simplex virus thymidine kinase gene/ganciclovir (HSV-tk/GCV) approach by the addition of several commonly clinical chemotherapeutic agents on hormone refractory prostate cancer (HRPC) cells PC-3m were investigated. After transferring of the HSV-tk gene into PC-3m cells, mRNA and protein expression of HSV-tk was detected by reverse-transcript polymerase chain reaction (RT-PCR) and strept avidin-biotin complex (SABC) immunohistochemical method. The killing effect of GCV, cisplatin (CDDP), etoposide (VP-16), vincristine (VCR), methotrexate (MTX), 5-fluorouracil (5-Fu), and suramin on PC-3m cells was evaluated by morphological assessment analysis, trypan blue exclusion assay and MTT assay respectively. Additionally, the cooperative effect of HSV-tk/GCV system combined with the above agents on the target cancer cells was determined by MTT. Furthermore, apoptosis and necrosis induced by GCV plus 5-Fu or suramin was analyzed by flow cytometry (FCM). The results showed that that there was HSV-tk mRNA and protein expression in pDR2-tk plasmid transduced PC-3m cell. Combination of GCV with VP-16, VCR, 5-Fu or suramin led to an enhanced cellular killing effect, but with CDDP resulted in a reduced one and with MTX in an approximate one. FCM revealed that synergistic use of GCV and 5-fu or suramin resulted in a rather large proportion of apoptosis and necrosis with the apoptosis index being 36.38% and 35.51%, and the proportion of necrosis being 33.05% and 28.87%, respectively. In conclusion, HSV-tk/CGV approach by addition of certain clinical available chemotherapeutic drugs brings on statistically significant enhanced cell killing over single-agent treatment. Our results highlight the potential for such new combination therapies for future treatments of HRPC.

Gene therapy using adenoviral vector encoding 4-1BBIg gene significantly prolonged murine cardiac allograft survival

4-1BB, a member of the tumor necrosis factor (TNF) receptor superfamily, interacts with 4-1BBL expressed on APC and delivers a costimulatory signal for T cell activation and growth. In this study, we investigated the efficacy of an adenoviral vector encoding murine 4-1BB extracellular domain and human IgG1 Fc (Ad4-1BBIg) fusion gene on murine cardiac allograft survival. Abdomen heterotopical heart graft model was performed from Balb/c to C57BL/6 mice. The adenoviral vectors, Ad4-1BBIg or an adenoviral vector containing EGFP gene (AdEGFP), were administered intravenously to recipient animals after cardiac grafting. The cardiac allograft survival was monitored by daily palpation. The serum level of 4-1BBIg and graft histology was assessed. Cytokine profiles in the grafts were detected by RT-PCR. IFN-gamma producing cells in recipient spleen were examined by flow cytometry. 4-1BBIg gene expression was achieved highly level at 72 h after vector injection. The proportion of IFN-gamma producing cells in recipient spleen was significantly reduced after administration of Ad4-1BBIg, compared to the group given AdEGFP or to the untreated control group. Unlike in controls, cardiac allograft expression of mRNA coding for IL-2 and IFN-gamma remained low in the Ad4-1BBIg group. Ad4-1BBIg therapy markedly reduced T cell infiltration into the graft and significantly prolonged recipient survival time (13.5 days), compared to the untreated group (7.5 days) and the AdEGFP-treated group (8.0 days) (P < 0.05). These results indicate that blockade of 4-1BB/4-1BB ligand interactions by Ad4-1BBIg inhibited alloreactive T-cell activation and attenuated T-cell infiltration into the graft, resulting in significant prolongation of murine cardiac allograft survival. Therefore, Ad4-1BBIg may be useful for preventing allograft rejection.

4-Nitroquinoline-1-oxide-induced mutagen sensitivity and risk of nonmelanoma skin cancer: a case-control analysis

The UV radiation-mimetic chemical 4-nitroquinoline-1-oxide (4-NQO) is thought to induce squamous cell carcinoma (SCC) similar to those induced by UV radiation in animals. Therefore, we tested the hypothesis that cellular sensitivity to 4-NQO is associated with risk of developing skin cancer in a case-control study of 191 patients with nonmelanoma skin cancer (NMSC; 81 SCC and 110 basal cell carcinoma (BCC)) and 176 cancer-free controls. Short-term blood cultures were treated with 4-NQO at a final concentration of 10 microM for 24 hours and scored for chromatid breaks in 50 well-spread metaphases. We found that the mean frequency of chromatid breaks per cell (b/c) was significantly higher in the cases (mean+/-SD, 0.46+/-0.43 for SCC and 0.43+/-0.38 for BCC) than in the controls (0.25+/-0.25; P<0.001 for both comparisons) and were associated with more-than-twofold increased risk for both SCC and BCC after adjustment for known risk factors. Therefore, our findings support the notion that sensitivity to 4-NQO reflects susceptibility to UV-induced NMSC. However, there is a lack of correlation between UVB-induced b/c and 4-NQO-induced b/c in this study population. Therefore, these findings need to be verified by additional studies.

[Clone and expression of murine BTLA extracellular domain gene and its effect on the expression of B7 on dendritic cells]

AIM

To study the regulatory effect of recombinant glutathione S-transferase (GST)-extracellular domain of murine B and T lymphocyte attenuator (mBTLAext) fusion protein GST-mBTLAext on the expression of B7 on murine dendritic cell (DC) line DC2.4.

METHODS

cDNA of mBTLA was amplified from total RNA of murine splenocytes by RT-PCR. The recombinant prokaryotic expression vector pGEX-4T-2/mBTLAext was constructed by cloning mBTLAext into pGEX-4T-2 and then transformed into E. coli BL21 (DE3). The fusion protein GST-mBTLAext was expressed under the induction of 1 mmol/L IPTG, and then was extracted from inclusion body and purified through Glutathione Sepharose 4B chromatography column. The fusion protein was added into the culture supernatant of DC2.4 and its effect on the expression of B7-1 and B7-2 on DC2.4 was analyzed by flow cytometry.

RESULTS

The recombinant prokaryotic expression vector pGEX-4T-2/mBTLAext was constructed and the fusion protein GST-mBTLAext was expressed successfully. The molecular weight of the fusion protein was 43.0 kDa, determined by SDS-PAGE, which was corresponding to expectation. GST-mBTLAext could up-regulate the expression of B7-1, but didn't alter the expression of B7-2, on DC2.4 in a dose dependent manner.

CONCLUSION

BTLA had a regulatory effect on the expression of B7 on DC. It is significant to study the effect of BTLA on the biological behaviour of DC and its molecular mechanism.

Soluble mouse B7-H3 down-regulates dendritic cell stimulatory capacity to allogenic T cell proliferation and production of IL-2 and IFN-gamma

B7-H3 is a recently identified member of the B7 gene family. Its ubiquitous expression in both lymphoid and nonlymphoid tissues suggests that it could play an important role in the maintenance of self-tolerance. However, the exact function of B7-H3 is still elusive. The purpose of current study is to demonstrate the possible function of soluble mouse B7-H3 for prevention of DC-mediated T cell activation. For this purpose, we established a soluble mouse B7-H3 fusion protein (mB7h3-hIg) eukaryotic expression vector (pmB7h3-hIg) with a C-terminal human IgG1 Fc. A C57BL/6 (B6)-derived dendritic cell line (DC2.4 cells) was used for the establishment of stable transfectants for generation of soluble mB7h3-hIg. Ectopic mB7h3-hIg expression was confirmed by RT-PCR, Western blot and ELISA analyses. A 49.7 kD protein was detected by Western blot from DC2.4 cells transfected with pmB7h3-hIg. It was found that soluble mB7h3-hIg expression has no effect on cell cycling and apoptosis and the expression of CD80 and CD86 of the DC2.4 cells. However, ectopic soluble mB7h3-hIg expression was found to significantly affect the allo-stimulatory capability for DC2.4 cells. DC2.4 cells expressing soluble mB7h3-hIg showed a significant reduced allo-stimulatory capability as compared with the controls determined by MLC. Further studies revealed that soluble mB7h3-hIg could also inhibit IL-2 and IFN-gamma production of allogenic T cells. These results suggested a great potential of soluble B7-H3 for treatment of graft rejection and autoimmume disease.

Functional polymorphisms in cell death pathway genes FAS and FASL contribute to risk of lung cancer

BACKGROUND

The FAS and FASL system plays a key role in regulating apoptotic cell death and corruption of this signalling pathway has been shown to participate in immune escape and tumorigenesis. There is reduced expression of FAS but elevated expression of FASL in many types of human cancers including lung cancer. We recently reported an association between functional polymorphisms in FAS (-1377G-->A) and FASL (-844T-->C) and risk of oesophageal cancer.

OBJECTIVE

To examine the contribution of these polymorphisms to risk of developing lung cancer.

METHODS

Genotypes of 1000 lung cancer patients and 1270 controls were analysed by PCR based restriction fragment length polymorphism. Associations with risk of lung cancer were estimated by logistic regression.

RESULTS

Compared with non-carriers, there was a 1.6 fold excess risk of developing lung cancer for carriers of the FAS -1377AA genotype (odds ratio (OR) 1.59, 95% confidence interval (CI) 1.21 to 2.10; p = 0.001), and 1.8 fold excess risk (OR 1.79, 95% CI 1.26 to 2.52; p = 0.001) for carriers of FASL -844CC. Gene-gene interaction of FAS and FASL polymorphisms increased risk of lung cancer in a multiplicative manner (OR for the carriers of both FAS -1377AA and FASL -844CC genotypes 4.18, 95% CI 2.83 to 6.18). Gene-environment interaction of FAS or FASL polymorphism and smoking associated with increased risk of lung cancer was also found.

CONCLUSION

These results are consistent with our initial findings in oesophageal cancer and further support the hypothesis that the FAS and FASL triggered apoptosis pathway plays an important role in human carcinogenesis.