Adjuvant Effects of Dual Co-stimulatory Molecules on Cellular Responses to HIV Multiple-epitope DNA Vaccination

Designing adjuvants that can induce strong cytotoxic T cell responses is largely required for preparing DNA vaccines. In this study we explored dual costimulatory molecules 4-1BBL and OX40L as adjuvants to improve the efficiency of the HIV multiple-epitope DNA vaccine. When explored in the human dendritic cell-T cell based coculture system, dual costimulatory molecules significantly enhanced the anti-HIV T cell response of the HIV multiple-epitope DNA vaccine, as detected by intracellular cytokine staining to HIV antigens, cytokines accumulation in the cultures, and antigen-specific cytotoxic T lymphocyte responses. These results suggest that dual costimulatory molecules 4-1BBL and OX40L can effectively increase the potential of the HIV multiple-epitope antigen DNA vaccine and may provide an exciting approach for HIV therapy.

Expression of co-stimulatory molecules B7-2 and PD-L1 on peripheral blood mononuclear cells in patients with chronic hepatitis B virus infection

Objective： To explore the roles of the expression of the co-stimulatory molecule, B7-2, and the co-inhibitory molecule, PD-L1, on peripheral blood mononuclear cells in the mechanism of immunotolerance in chronic hepatitis B virus infection. Methods： Thirty HBV infected patients in the immunoreactive phase and 20 patients in the immunotolerant phase were enrolled in the study, while 20 healthy volunteers were used as controls. RT- PCR and real-time PCR methods were used to detect the expression levels of B7-2 and PD-L1 mRNA in peripheral blood mononuclear cells in chronic HBV infected patients. Results： The B7-2 expression in irnrnunoreactive and immunotolerant patients was significantly lower than that in the controls （P all 〈 0.01 ）; B7-2 expression in immunoreactive patients was significantly lower than in immunotolerant patients （P 〈 0.01）. PD-L1 expression in irnmunoreactive patients and immunotolerant patients was significantly higher than that in normal controls （P all 〈 0.01）. The PD-L1/BT-2 ratios in immunoreactive and immunotolerant patients were significantly higher than that of the healthy controls （P all 〈 0.01）; the PD-L1/ B7-2 ratio was significantly higher in the immunoreactive patients than in the immunotolerant patients （P 〈 0.01）. Conclusion： In chronic HBV infection, changes in the expression of co-stimulatory and co-inhibitory molecules imply a protective adjustment against the patient＇ s immune response that may result in increased immunotolerance and persistent HBV infection.

Estradiol regulates T cell activation by influencing co-stimulatory molecules transcription

To investigate whether estradiol （E2） plays a role in cell-contact-dependent regulatory mechanism of T cell activation, we studied the role of E2 in regulating gene transcription of CTLA-4, ICOS, B7-1, B7-2 and B7h in vitro. The splenic cells of normal female BALB/c mice were activated by ConA. Then the cells were cultured with E2 （100 pg/ml or 50 ng/ml） for 24 h or 48 h, respectively. The cell proliferation was measured by MTF assay and the expression of the co-stimulatory molecules mRNA was examined by RT-PCR analysis. We found that E2 （100 pg/ml, physiological level） stimulated the acti- vated spleen cells proliferation; inhibited CTLA-4, ICOS, TGF-β and IL-10 gene transcription; promoted B7-1 and B7-2 gene transcription. E2 （50 ng/ml, pregnant level） inhibited the proliferation of the activated splenic cells; promoted CTLA-4, B7-1, IL-10 but inhibited B7-2 and TGF-β gene transcription. Therefore, we conclude that the effects of E2 on T cell activation are partially through its regulation on the co-stimulatory molecules. The co-stimulatory molecules are crucial components of the cell-contact dependent regulatory mechanism, and E2 may regulate T cell activation by this mechanism.

Historical evolution,overview,and therapeutic manipulation of costimulatory molecules

Co-stimulatory molecules are key mediators in the regulation of immune responses and knowledge of its different families,structure,and functions has improved in recent decades.Understanding the role of co-stimulatory molecules in pathological processes has allowed the development of strategies to modulate cellular functions.Currently,modulation of co-stimulatory and co-inhibitory molecules has been applied in clinical applications as therapeutic targets in diseases and promising results have been achieved.

Probiotic metabolites from Bacillus coagulans GanedenBC30^(TM) support maturation of antigen-presenting cells in vitro

AIM:To study the effects of probiotic metabolites on maturation stage of antigen-presenting immune cells.METHODS:Ganeden Bacillus coagulans 30(GBC30) bacterial cultures in log phase were used to isolate the secreted metabolite(MET) fraction.A second fraction was made to generate a crude cell-wall-enriched fraction,by centrifugation and lysis,followed by washing.A preparation of MET was subjected to size exclusion centrifugation,generating three fractions:< 3 kDa,3-30 kDa,and 30-200 kDa and activities were tested in comparison to crude MET and cell wall in primary cultures of human peripheral blood mononuclear cell(PBMC) as a source of antigen-presenting mononuclear phagocytes.The maturation status of mononuclear phagocytes was evaluated by staining with monoclonal antibodies towards CD14,CD16,CD80 and CD86 and analyzed by flow cytometry.RESULTS:Treatment of PBMC with MET supported maturation of mononuclear phagocytes toward both macrophage and dendritic cell phenotypes.The biological activity unique to the metabolites included a reduction of CD14+ CD16+ pro-inflammatory cells,and this property was associated with the high molecular weight metabolite fraction.Changes were also seen for the dendritic cell maturation markers CD80 and CD86.On CD14dim cells,an increase in both CD80 and CD86 expression was seen,in contrast to a selective increase in CD86 expression on CD14bright cells.The co-expression of CD80 and CD86 indicates effective antigen presentation to T cells and support of T helper cell differentiation.The selective expression of CD86 in the absence of CD80 points to a role in generating T regulatory cells.CONCLUSION:The data show that a primary mechanism of action of GBC30 metabolites involves support of more mature phenotypes of antigen-presenting cells,important for immunological decision-making.

Study of human B7 homolog 1 expression in patients with hepatitis B virus infection

AIM: To further investigate the role of human B7 homolog 1 (B7-H1) in the mechanism of persistent hepatitis B virus (HBV) infection. METHODS: Peripheral and intra-hepatic B7-H1 expression were compared by flow cytometry and immunochemical staining between two 2 distinct groups, one being chronic HBV tolerance patients (CHB-T) and the other being acute hepatitis B patients (AHB). B7-H1 mRNA expression level was also compared by real time polymerase chain reaction between CHB-T and AHB patients. The location of intra-hepatic B7-H1 and CD40 expression were analyzed by immunofluorescence. The levels of B7-H1 and CD40 expression on cultured myeloid dendritic cells (mDCs) with or without hepatitis B surface antigen (HBsAg) treatment were analyzed dynamically by flow cytometry. Intracellular interferon-γ (IFN-γ) staining and the stimulatory capacity of mDC of cultured mDC with or without HBsAg treatment were also compared by flow cytometry. RESULTS: Peripheral B7-H1 expression on mDCs was increased significantly in AHB compared to CHB-T patients (P < 0.05). In the liver tissues from CHB-T patients, B7-H1 positive cells were almost absent despite a persistently elevated serum HBsAg load. In contrast, there were indeed increased B7-H1-positive cells in situ in the liver tissue from AHB. In vitro analysis showed the parallel upregulation of B7-H1 and CD40 on CD11c+ mDCs after the onset of stimulation. Addition of recombinant hepatitis B surface antigen (rHBsAg) significantly decreased CD40 expression (P < 0.05 at 16 h, 20 h and 24 h time points). B7-H1 expression was also inhibited by rHBsAg, and the inhibition rate of CD40 was greater than that of B7-H1. This preferential inhibition of CD40 expression on mDCs by rHBsAg resulted in the dysfunction of mDCs and T cells in the mixed leucocyte reaction (MLR) system. With rHBsAg pretreatment, in a carboxyfluorescein diacetate succinimidyl ester (CFSE) labeled MLR system at a ratio of 1:5 responder cell-stimulator cell (R/S), the CFSE dim percentage of T cells decreased from 85.1% to 25.4% and decreased from 30.3% to 12.0% at 1:10 R/S. IFN-γ production by CD8+ T cells, in the MLR system, was reduced significantly by HBsAg pretreatment. At ratios of 1:5 R/S, the percentage of IFN-γ and CD8 dual positive T cells decreased from 55.2% ± 5.3% to 15.1% ±3.1% (P < 0.001), and decreased from 35.0% ± 5.1% to 7.3% ± 2.7% at ratios of 1:10 R/S (P < 0.001). CONCLUSION: B7-H1 is not a signature of immune dysfunction, but an inflammation marker. HBsAg regulate immune response by tipping the balance between B7-H1 and CD40.

Suppression of Allogeneic T Cells Proliferation by CD3/CD46-Induced T-regulatory 1 Cells

CD46 is not only identified as a complement regulatory protein which protects host cells from complement attack,but also a new co-stimulatory molecule for human T cells.CD3/CD46 co-stimulation can induce a T-regulatory 1 cell(Tr1)-specific cytokine phenotype in human CD4+ T cells.However,the role of CD46 as a co-stimulatory molecule in the modulation of the acquired immunity,such as transplant immunology,remains unclear.In this study,CD4+ T cells were isolated from human CD46-transgenic C57BL/6 mice by magnetic-activated cell sorting,and further induced by anti-CD3,anti-CD28 and anti-CD46 antibodies respectively,and anti-CD3/anti-CD28 antibodies,anti-CD3/anti-CD46 antibodies,or the monoclonal antibody panel against CD3/CD28/CD46.The levels of interleukin-2(IL-2),γ-interferon(γ-IFN),interleukin-10(IL-10) and transforming growth factor-β(TGF-β) were detected in the supernatants of different groups.Suppression of allogeneic T cell proliferation were assessed by using mixed lymphocyte reaction(MLR) assay,in which monoclonal antibodies against CD46 were added to the culture.The results showed that CD3/CD28,CD3/CD46 and CD3/CD28/CD46 co-stimulation could significantly induce stronger proliferation of T cells than CD3 stimulation(P<0.05),and CD3/CD28/CD46 co-stimulation significantly increased the proliferation of T cells when compared with CD3/CD28 or CD3/CD46 co-stimulation(P<0.05 for each).IL-2 and γ-IFN levels were much higher in CD3/CD28 co-stimulation group than in CD3,CD28,CD46 and CD3/CD46 groups(P<0.05 for each).IL-10 and TGF-β levels were dramatically increased in CD3/CD46 co-stimulation group as compared with those in the CD3,CD28,CD46 and CD3/CD28 groups(P<0.05 for each).CD3/CD46 co-stimulation significantly inhibited the T cell proliferation and allogenic immune responses through the secretion of IL-10 and TGF-β in MLR(P<0.05).These results suggested that CD3/CD46 can induce Tr1 cells to modulate allogenic immune responses,and it may become a novel target for the development of new therapeutic approach for T-cell-mediated diseases.CD46 plays an important role in regulating the T cell-mediated immune responses by bridging innate and acquired immunity.

Research progress of ICOSL/ICOS pathway in maternal-fetal immune tolerance

Co-signaling molecules are molecules whose ligands on the surface of cells interact with receptors on the surface of T cells to convey stimulatory or inhibitory signals to regulate immune responses.Co-signaling molecules play an important role in tumor and autoimmune diseases.Lately,studies have shown that co-signaling molecules are also involved in the regulation of maternal-fetal immune tolerance,and abnormalities of co-signaling molecules may lead to the imbalance of maternal-fetal immune tolerance,resulting in recurrent abortion,eclampsia and other pregnancy complications.ICOSL/ICOS is a ligand and receptor of costimulatory signals,which regulates maternal and fetal immune tolerance by participating in T cell differentiation and Th1 and Th2 cytokine secretion.Therefore,this article reviews the structure of ICOSL/ICOS,the distribution of ICOSL/ICOS at the maternal-fetal interface and its immune regulation during pregnancy,in order to provide new ideas for the future study of immunotherapy of pregnancy complications caused by abnormal co-signaling molecules.