ABSTRACT
Objective To explore the effects of murinecytomegalovirus(MCMV)infected mouse embryonic fibroblasts(MEF)on the proliferation and activation of regulatory T cell in vitro. Methods A co-culture system of T cell and MCMV infected MEF(T-MEF MCMV)was established.The viral load of supernatant was determined by plaque assay.The proliferation of T cells was observed with cell counting.The proportion of CD4+ CD25+ cells was measured by flow cytometry.The levels of Foxp3 protein were measured by Western blot.Reverse transcription polymerase chain reaction(RT-PCR)assay was utilized tO determine whether MCMV infection of MEF influenced the level of transforming growth factor(TGF)-β mRNA.The level of TGF-β protein in supernatant was measured by double-antibody sandwich enzyme linked immunosorbent assay(ELISA).The difference between T-MEF MCMV group and control group was assessed by one-way ANOVA.Results When T cells were co-cultured with MCMV infected MEF for 1 day and 3 days,the viral load in supernatant decreased.But when co-culture lasted for 6 days,the antiviral effect obviously diminished,as the viral load[(5.58±0.67)×105 PFU/mL]of the experimental group showed no statistic difference with MEF MCMV control group[(6.05±0.34)×105PFU/mL].When co-cultured with MCMV infected MEF for 3 days,T cell increased from pre-culture level of[(2.02±0.05)×106/mL]to(2.25± 0.13)×106/mL(P＜0.05).But when co-culture lasted for 6 days,the number of T eelI returned to (2.08±0.14)×106/mL,which had no statistic difference with that of co-culture for 3 days system. Both the expressions of Foxp3 protein and the proportion of CD4+ CD25+ Foxp3+ Treg cells in T-MEF MCMV group were up-regulated as the infection time extended,which were two times and three times of the control group level,respectively.The mRNA level(A value)of TGF-β in MCMV infected MEF increased from baseline of 1.09±0.13 to 3.15±0.54 on day 3 after infection.The expression of TGF-β in supernatant 3 days after infection was(3.85±0.32) μg/L,which was significantly higher than that before infection[(1.74±0.14)μg/L,P＜0.05].Conclusions Activated T cells have antiviral effect.However,the function of T cells is rapidly inhibited after activation,which may be due to the expression of Foxp3 mRNA induced by MCMV infected MEF and increased CD4+ CD25+ Treg proportion of the co-cultured T cells.TGF-β level is significantly increased after CMV infection,which may be an important mechanism of Treg proliferation.MCMV may manipulate Treg to evade specific immune elimination and,as a result,to cause CMV replication.
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Objective To investigate the influence of murine cytomegalovirus on the expansion of CD+CD25+ Foxp3+ regulatory T cell (Treg) and the activation of CD4+ CD25+Foxp3 - effector T cell (TE) in vivo. Methods Forty-two BALB/c mice were intraperitoneally inoculated with appropriate amount ofMCMV Smith strain for establishing the model of infection, another 42 mice served as mocked-infected con-trois. Day 28 post MCMV infection was determined to be the demarcation point of the acute and chronic in- fection based on the viral load of major visceral organs. On day 1,3, 7, 14, 28, 45 and 60 post infection, splenocytes were prepared by means of routine method. The proportions of CD4+CD25+ Foxp3+Treg and CD4+CD25+Foxp3- activated TE in T lymphocyte were measured by flow cytometry. Results The propor- tion of CD+CD25+ Foxp3+ T cells in T lymphocytes was persistently suppressed since day 7 post infection, and fell to the lowest level on day 28 post infection (P <0.01), then zoomed and reached the peak value on day 60 post infection (P < 0.05). CD4+CD25+ Foxp3 - TE proportion was up to the highest on day 3 post infection(P < 0. 01), then suppressed and in significantly lower level since day 45 post infection (P < 0.05). Treg/CD+TE ratio was in lower level on day 3 to 14 post infection(P <0.05) ; but on day 45 and day 60 post infection Treg/CD+ TE ratio was markedly increased (P < 0.05). Conclusion MCMV infec- tion can increase the CD+CD25+Foxp3+ Treg proportion, and inhibit CD4+T cells activation in chronic in- fection phase, which is likely to suppress the function of antiviral immunity in the infected host to cause a persistent latent infection.
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Objective To explore the role of CD4+CD25+regulatory T cells(Treg)in the co-culture svstem consisting of T cells and mouse embryo fibroblasts(MEF)infected with murine cytomegalovirus (MCMV)in vitro.Methods A co-culture system of T cells and MCMV infected MEF(MEFMCMV)was established.The viral load in the supernatants was determined by plaque assay.TH1/TH2 differentiation-specific transcription factors T-bet/GATA-3 were assayed by Western blot.The levels of cytokines IL-4,IL-10and IFN-γ in the co-culture supenatants were measured by double-antibody sandwich ELISA.Results After 3 d incubation,the viral load in the supernatants of TdepTreg-MEFMCMC group,in which the T cells depleted Treg(TdepTreg)were co-cultured together with MEFMVMV,was significantly lower than that in MEFMCMV group.And in the co-cultivation of MEFMCMV and T cells without Treg the expressions of T-bet/GATA-3,IL-4,IL-10 and IFN-γ incteased significantly.Compared with the virus content in the TdepTreg-MEFMCMV group,the MCMV load in the"add-on Treg group"increased and the levels of T-bet/GATA-3 and IFN-γ were lower,and the expression of IL-4 didn't show any significant difference. Compared with the level of IL-10 in the TdepTreg-MEFMCMV group,the IL-10 level in the"add-on TREG group"didn't show any significant differece when the Treg ratio among total T cells was 1%～2%,and increased significantly when the Treg ratio was more than 5%.These eflfects were all correlated with Treg ratios in a dose-dependent manner.Conclusion MCMV infected MEF can induce the proliferation and activation of effector T cells,but Treg can inhibit the T cell-mediated protective effect on MCMV infection.
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To establish a method of directional differentiation and efficient production of neurons from embryonic stem cells (ES cells) in vitro, based on the 4-/4+ protocol described by Bain, a new method was established to induce ES cells differentiating into neurons by means of three-step differentiation using all-trans retinoic acid (ATRA) combined with astrocyte-conditioned medium (ACM) in Vitro. The totipotency of ES cells was identified by observation of cells' morphology and formations of teratoma in immunocompromised mice. The cells' differentiation was evaluated continuously by the detection of the specific cellular markers of neural stem ceils, neurons and astrocytes,including nestin, NSE and GFAP using immunohistochemistry assay. The NSE positive cells' ratio of the differentiated cells was determined by flow cytometry. It was found that the transparent circular clusters surrounding embryoid bodies induced with combining induction protocol formed just after 24 h and gradually enlarged later. This phenomenon could not be observed in EBs induced only by ATRA. The NSE positive cells' ratio irthe cells induced with ATRA and ACM was higher than that of the cells induced by ATRA at different time points of differentiation, and finally reached up to 73.5 % among the total differentiated population. It was concluded that ES cells could be induced into neurons with high purity and yield by means of inducing method combining with ATRA and ACM.
ABSTRACT
To establish a method of directional differentiation and efficient production of neurons from embryonic stem cells (ES cells) in vitro, based on the 4-/4+ protocol described by Bain, a new method was established to induce ES cells differentiating into neurons by means of three-step differentiation using all-trans retinoic acid (ATRA) combined with astrocyte-conditioned medium (ACM) in Vitro. The totipotency of ES cells was identified by observation of cells' morphology and formations of teratoma in immunocompromised mice. The cells' differentiation was evaluated continuously by the detection of the specific cellular markers of neural stem cells, neurons and astrocytes, including nestin, NSE and GFAP using immunohistochemistry assay. The NSE positive cells' ratio of the differentiated cells was determined by flow cytometry. It was found that the transparent circular clusters surrounding embryoid bodies induced with combining induction protocol formed just after 24 h and gradually enlarged later. This phenomenon could not be observed in EBs induced only by ATRA. The NSE positive cells' ratio in the cells induced with ATRA and ACM was higher than that of the cells induced by ATRA at different time points of differentiation, and finally reached up to 73.5% among the total differentiated population. It was concluded that ES cells could be induced into neurons with high purity and yield by means of inducing method combining with ATRA and ACM.
Subject(s)
Astrocytes/cytology , Cell Differentiation , Cells, Cultured , Embryo, Mammalian , Neurons/cytology , Stem Cells/cytology , Tretinoin/pharmacologyABSTRACT
The present study aimed to find out dynamic changes of apoptosis in human cytomegalovirus (HCMV) infected cells and the influence of HCMV infection on activation of caspase3 and the expression of apoptosis-regulating genes, bcl-2 and fas mRNA. The sequential changes of apoptotic cell rate in high and low MOI (MOI= 2.5 and 0.25 respectively) of HCMV infected human embryonic lung fibroblasts (HELFs) at 1 h, 12 h, 24 h, 36 h, 48 h, 72 h and 96 h post-infection were measured by flow cytometry. The expression levels of caspase-3 protein and bcl-2 and fas mRNA in HCMV infected cells (MOI=0.25) at 72 h post-infection were detected by Western blot and in situ hybridization methods, respectively. It was found that the ratio of apoptotic cells in normal controls was consistently lower, but the rates in low and high MOI infected cells were gradually increased with time prolonged, reached peak at 96 h (8.85 %) and 72 h (25.63 %), respectively. By Western blot analysis, only a narrow band of 32 kD (1 kD=0. 992 1 ku) procaspase-3 was found in normal cells, but a wider procaspase-3 band and a much wider band of 17 kD proteins (p17) appeared in the infected cells. Meanwhile, the expression of bcl-2 mRNA was higher and that of fas mRNA was lower in the normal HELF cells, whereas there were significantly lower bcl-2 mRNA and higher fas mRNA expression levels in HCMV infected cells. It was concluded that HCMV was a stronger inducer of apoptosis in HELF cells. Caspase-3, as the marker of undergoing apoptosis,was expressed increasingly and activated in the infected cells, indicating its action in HCMV-inducing apoptosis. Down-regulating bcl-2 mRNA expression and up-regulating fas mRNA expression were also involved in the mechanism of HCMV-induced apoptosis.
ABSTRACT
In order to investigate the human cytomegalovirus (HCMV) infection, the mouse cytomegalovirus (MCMV) infected mice were experimentally studied. 6 to 8 week old female BALB/C mice with immunosuppression were selected to undergo the MCMV inoculations: intracranial inoculation and peritoneal inoculation. MCMV of the infected mice in various organs and tissues were detected by using beta-gal staining and in situ nucleic acid hybridization assay. The pathological changes were observed in HE staining paraffin-embedded sections. It was found that all the MCMV infected mice showed the retardation of growth and development, and feather looseness. Both intracranial inoculation of 10(4) PFU viruses or peritoneal inoculation of 10(6) PFU viruses resulted in the pathological changes, to some extent, of various organs and tissues in the mice. The pathological changes in liver were consistent with the amount of beta-gal staining positive cells, indicating the liver lesions were mainly caused by viral proliferation. It was also found that the viruses in the immunosuppressed mice subjected to intracranial inoculation could spread to whole body organs, while the viruses in the immunosuppressed mice subjected to intrapeitoneal inoculation couldn't spread to the brain, suggesting blood-brain barrier could prevent the virus from spreading to the brain.
Subject(s)
Animals , Female , Mice , Blood-Brain Barrier , Brain , Pathology , Virology , Disease Models, Animal , Herpesviridae Infections , Pathology , Virology , Immunocompromised Host , Liver , Pathology , Virology , Lung , Pathology , Virology , Mice, Inbred BALB C , MuromegalovirusABSTRACT
In order to investigate the human cytomegalovirus (HCMV) infection, the mouse cytomegalovirus (MCMV) infected mice were experimentally studied. 6 to 8 week old female BALB/C mice with immunosuppression were selected to undergo the MCMV inoculations: intracranial inoculation and peritoneal inoculation. MCMV of the infected mice in various organs and tissues were detected by using beta-gal staining and in situ nucleic acid hybridization assay. The pathological changes were observed in HE staining paraffin-embedded sections. It was found that all the MCMV infected mice showed the retardation of growth and development, and feather looseness. Both intracranial inoculation of 10(4) PFU viruses or peritoneal inoculation of 10(6) PFU viruses resulted in the pathological changes, to some extent, of various organs and tissues in the mice. The pathological changes in liver were consistent with the amount of beta-gal staining positive cells, indicating the liver lesions were mainly caused by viral proliferation. It was also found that the viruses in the immunosuppressed mice subjected to intracranial inoculation could spread to whole body organs, while the viruses in the immunosuppressed mice subjected to intrapeitoneal inoculation couldn't spread to the brain, suggesting blood-brain barrier could prevent the virus from spreading to the brain.
Subject(s)
Blood-Brain Barrier , Brain/pathology , Brain/virology , Disease Models, Animal , Herpesviridae Infections/pathology , Herpesviridae Infections/virology , Immunocompromised Host , Liver/pathology , Liver/virology , Lung/pathology , Lung/virology , Mice, Inbred BALB C , MuromegalovirusABSTRACT
AIM: To investigate whether efficient production of neuron-like cells from embryonic stem cells(ESCs) can be indued by astrocyte-conditioned medium(ACM) in vitro.METHODS: Based on the 4-/4+ protocol established by Bain,two groups were studied: ATRA group,ATRA with ACM group.ESCs were induced into neuron-like cells by means of three-step differentiation in vitro.The totipotency of ESCs was identified by the observation of cells' morphology and the formations of teratoma in immunocomprised mice.The cell differentiation was evaluated continuously by detection of the cellular specific markers of neural stem cell, neurons and astrocytes such as nestin,NF-200,NSE and GFAP using immuno-histochemistry assay.RESULTS:(1) The ESC-D3 cells kept the ability of differentiation into cellular derivations of all three primary germ layers after continuous passage culture.(2) The ratio of NF-200 and NSE positive cells in the cells induced by ATRA with ACM was higher than that in the cells induced by ATRA only.(3) Finally,the positive rate of the neuron-like cells was up to 73.5% in the group induced by ATRA with ACM.CONCLUSION: The ESCs are induced into neuron-like cells with high purity and efficiency by ATRA with ACM.