Biomedical subjects

Guoxing Zheng

Publications and source records attributed to Guoxing Zheng.

10 recordsLinked to original sources

PubMed2007

Modifying dendritic cells via protein transfer for antitumor therapeutics.

PURPOSE: The modification of therapeutic dendritic cells (DC) with various immunostimulatory molecules represents a useful means for improving the antitumor efficacy of DC transfer-based immunotherapy. We have evaluated the feasibility of modifying therapeutic DCs with multiple immunostimulatory molecules using a time-efficient, protein transfer (or protein "painting")-based method. EXPERIMENTAL DESIGN: Bone marrow-derived DCs were painted with either control protein human IgG (hIgG) or three immunostimulatory molecules, SLC, 4-1BBL, and TRANCE (the triad protein). Painted DCs were injected intratumorally into mice bearing established tumors. Subsequently, the capacities of painted DCs to migrate to the draining lymph nodes, recruit the host T cells, promote Th1 cytokine responses, and elicit therapeutic antitumor responses were evaluated. RESULTS: The triad protein transfer yields a uniform population of DCs that coexpress all three of the proteins. Compared with the hIgG-painted DCs, the triad protein-painted DCs migrate more efficiently to the draining lymph nodes and show enhanced capabilities to induce T cell infiltration of tumors and to promote Th1 cytokine responses in vivo. Furthermore, in both the EG.7 and TRAMP-C2 tumor models, compared with the DCs painted with hIgG or only one of the three proteins, the triad protein-painted DCs, upon adoptive transfer, elicit stronger therapeutic responses against established tumors. Importantly, the antitumor responses of the triad protein-painted DCs are mediated by systemic antitumor immunity. CONCLUSIONS: This study establishes, for the first time, the feasibility of optimizing DC transfer-based immunotherapy via combinatorial protein transfer of therapeutic DCs with an array of immunostimulatory molecules.

Animals↗

PubMed2006

Co-inoculation of DNA and protein vaccines induces antigen-specific T cell suppression.

Immunization can sometimes lead to antigen-specific immune suppression. In this study, we investigated this phenomenon by testing several combinations of DNA and protein vaccines directed against various viruses. We find that co-inoculation of mice with combined DNA and protein vaccines induces immune suppression if the two vaccines are "matched" by targeting the same antigen. Conversely, vaccine combinations never lead to immune suppression if they are derived from different viruses and, thus, mismatched antigenically. We have further identified CD4+CD25- T cells as the type of regulatory T cells induced by and are responsible for suppressing T cell activities in an antigen-specific manner in immunized animals. These regulatory T cells are phenotypically unique in their expression of Foxp3, IL-10, and IFN-gamma. Our study thus shows for the first time that co-administration of antigen-matched DNA and protein vaccines can generate this type of adaptive regulatory T cells.

Animals↗

PubMed2006

Arming tumor-reactive T cells with costimulator B7-1 enhances therapeutic efficacy of the T cells.

T cells ectopically expressing costimulators are pathogenic and contribute to autoimmunity against self-antigens. Given that tumor antigens are often self-antigen or mutated self-antigens, we hypothesize that neoexpressing a costimulator on tumor-reactive T cells may likewise enhance their reactivity to tumor. To test this hypothesis, we have expressed B7-1 on OT-1 CD8+ T-cell receptor transgenic T cells via protein transfer (or protein "painting"). Naïve OT-1 T cells, after being painted with B7-1, can self-costimulate themselves, elicit enhanced proliferative and CTL responses to E.G7-ovalbumin tumor cells (expressing a cognate antigen), and become resistant to CD4+CD25+ regulatory T-cell-mediated suppression. Importantly, these T cells, when coimplanted with E.G7-ovalbumin tumor cells into a syngeneic host, are three to nine times more potent than are control T cells (mock painted with human IgG) in inhibiting tumor growth. Further, on transfer into mice bearing established E.G7-ovalbumin tumors, B7-1-painted ex vivo-amplified OT-1 T cells induced complete tumor regression in 65% of treated mice, whereas the control T cells did so in only 28% of treated mice. Finally, on transfer into mice bearing less immunogenic 4T1 breast tumors, B7-1-painted tumor-reactive CD8+ T cells improved the survival of treated mice to a greater extent than did the control T cells. Hence, this study establishes that arming tumor-reactive T cells with a costimulator can enhance their antitumor efficacy.

Animals↗

PubMed2005

The adjuvant effect of levamisole on killed viral vaccines.

To explore adjuvants that are capable of promoting Th1-biased immune response, we investigated the usefulness of levamisole (LMS) as one such adjuvant for two different preparations of killed viral vaccines, derived from the foot mouth disease virus (FMDV) or the porcine respiratory reproductive syndrome virus (PRRSV) and tested respectively in BALB/c or C57 BL/6 mice. The results showed that LMS induced different types of immune responses in the host, depending on its dosage. While a high level of serum IgG was induced by using LMS at 2%, the most robust T cell proliferation was induced with LMS at 0.5%. The Th1 and Th2 cytokine profiles, which tracked well with the antibody and T cell responses, were similarly influenced by the dose of LMS. Moreover, the enhanced T cell response correlated with increased expression of MHC and co-stimulatory molecules and decreased expression of the suppressors of cytokine signaling molecules (SOCS1 and SOCS3) in the spleen, suggesting that it is mediated by the antigen presentation, co-stimulator signaling, and cytokine production pathways. These results establish that LMS can be used to induce Th1-biased immune responses when combined with killed-virus-based antiviral vaccines and that such adjuvant effect depends on the optimal LMS dosage.

Adjuvants, Immunologic↗

PubMed2005

Induction of active immune suppression by co-immunization with DNA- and protein-based vaccines.

Although immunization has been used for eliciting immune response, here we show that it can also induce immune suppression. When a DNA vaccine encoding a viral antigen such as the VP1 protein from the foot and mouth disease virus is administered together with its recombinant protein antigen or a viral preparation containing the same antigen, the immunized animals developed significantly reduced antigen-specific T cell-mediated responses and became impaired to subsequent rechallenge with the same antigen. The induction of immune suppression is mediated by suppressor T cells, as demonstrated by an adoptive transfer experiment and mixed lymphocyte reactions. The induction of immune suppression in immunized animals is also correlated with a shift of cytokine balance, as reflected by an elevated level of IL-10 and reduced level of IFN-gamma or IL-2. Hence, co-immunization with DNA- and protein-based vaccines may represent a novel means for inducing active suppression against untoward immunity.

Animals↗

PubMed2005

Micrograting-array beam-shaping technique for asymmetrical laser beams.

A beam-shaping technique is presented for asymmetrical laser beams with different beam waists and divergences in both vertical and horizontal directions. We utilize a pair of two-dimensional micrograting arrays to equalize the beam parameter products of an asymmetrical beam in orthogonal directions by deflecting the appointed parts of the beam on the longer side of the beam and by recombining the parts on the shorter side. When combined with divergent transformation by means of collimating optical components, the beam-shaping system can produce a symmetrical beam in orthogonal directions with optimized beam waists and divergences. A beam-equalization system is designed and demonstrated for a typical asymmetrical beam of a laser diode bar. In the experiment an emission beam with dimensions of 1 microm x 10 mm and half-divergences of 148 mrad x 576 mrad in the far field is transformed into an almost-square distribution with dimensions of -12 mm x 12 mm and half-divergences of -2 mrad x 2 mrad, which confirm the effectiveness of the proposed technique.

Journal Article↗

PubMed2004

TRANCE counteracts FasL-mediated apoptosis of murine bone marrow-derived dendritic cells.

Dendritic cells (DCs) are the most potent APCs known to date. Despite their potency, DCs are short-lived. During the course of an immune response, DCs interact with cognate T cells, which upon activation express both DC survival and pro-apoptotic factors. This raises the question how DC longevity is regulated by these signals. In this study, we have assessed the roles of FasL (CD95L) and tumor necrosis factor-related activation-induced cytokine (TRANCE) in regulating the survival of murine bone marrow-derived DCs (BMDCs). We have shown for the first time that TRANCE protects DCs from FasL-mediated apoptosis, and that the quantitative balance between TRANCE and FasL can modulate BMDC survival in vitro. In addition, by quantifying adoptively transferred BMDCs in draining lymph nodes (LNs), we have shown that treating DCs with FasL prior to the transfer decreases the quantity of donor DCs capable of migrating to the LN, presumably due to FasL-mediated apoptosis of donor DCs in vivo. Furthermore, we have shown that TRANCE can counteract FasL and reverse such decrease. Taken together, these results suggest that the interplay between FasL and TRANCE play a role in regulating the survival of DCs.

Animals↗

PubMed2004

The 4-1BB costimulation augments the proliferation of CD4+CD25+ regulatory T cells.

The thymus-derived CD4(+)CD25(+) T cells belong to a subset of regulatory T cells potentially capable of suppressing the proliferation of pathogenic effector T cells. Intriguingly, these suppressor cells are themselves anergic, proliferating poorly to mitogenic stimulation in culture. In this study, we find that the 4-1BB costimulator receptor, best known for promoting the proliferation and survival of CD8(+) T cells, also induces the proliferation of the CD4(+)CD25(+) regulatory T cells both in culture and in vivo. The proliferating CD4(+)CD25(+) T cells produce no detectable IL-2, suggesting that 4-1BB costimulation of these cells does not involve IL-2 production. The 4-1BB-expanded CD4(+)CD25(+) T cells are functional, as they remain suppressive to other T cells in coculture. These results support the notion that the peripheral expansion of the CD4(+)CD25(+) T cells is controlled in part by costimulation.

Animals↗

PubMed2003

Quantitative interplay between activating and pro-apoptotic signals dictates T cell responses.

Antigen-presenting cells (APC) can express surface ligands with both T cell activating and inhibitory capacities, prompting the question of how responding T cells integrate opposing trans signals concurrently delivered by APC. To address this question in a quantitative fashion, we turned to protein transfer as a unique experimental approach that is well-suited for addressing such questions from a quantitative standpoint. Costimulatory (either B7-1*Fc(gamma1) or Fc(gamma1)*4-1BBL) and pro-apoptotic (Fc(gamma1)*FasL) Fc fusion proteins were quantitatively "painted" in varying ratios onto surrogate APC pre-coated with palmitated-protein A, the latter serving as a surface anchor. Evaluating the signaling potential of these various painted cells in a standard in vitro T cell proliferation assay, we demonstrated that at a given level of TCR triggering, the quantitative balance between costimulator (B7-1 or 4-1BBL) and FasL dictates the magnitude of the proliferative T cell response. Furthermore, when the costimulator density is kept constant, there is also a quantitative balance between TCR-directed and FasL signals. Interesting species-specific nai;ve versus memory T cell subset differences emerged with regard to susceptibility to Fas-mediated apoptosis and costimulator:FasL opposition. Taken together, these data demonstrate for the first time a quantitative interplay between activating and pro-apoptotic trans signals that dictates the magnitude of T cell responses.

4-1BB Ligand↗

PubMed2003

New designs for cancer vaccine and artificial veto cells: an emerging palette of protein paints.

Antigen-presenting cells (APC) can be refaced with "protein paints" that change the appearance of their T cell-oriented trans signal arrays. Our group has developed three categories of protein paints suitable for this kind of APC engineering: artificial glycosylphosphatidylinositol (GPI) proteins, palmitated-protein A:Fc*1 fusion protein conjugates, and trans signal converter proteins. Protein paints have been devised with either immune enhancement or suppression in mind. Costimulator * GPI and palmitated-protein A costimulator * Fcgamma1 conjugates can be used to augment the immune-activating potential of tumor cells. Alternatively, protein paints can be designed to transform APC into artificial veto cells, in essence creating Trojan horses capable of inhibiting pathogenic T cells. Trans signal converter proteins (TSCP) have been devised for this purpose. Our first paradigmatic inhibitory TSCP, CTLA-4 * Fas ligand, binds to APC, and in so doing, simultaneously blocks B7 costimulation (via CTLA-4) and sends inhibitory trans signals (via Fas ligand) to T cells with dramatic efficacy. Protein transfer offers a number of advantages over gene transfer in facilitating quantitative and combinatorial protein expression and simplifying in vivo applications; the palette of protein paints with immunotherapeutic potential will undoubtedly continue to evolve.

Animals↗