Biomedical subjects

Wenbo Ma

Publications and source records attributed to Wenbo Ma.

13 recordsLinked to original sources

PubMed2026

Glucose-responsive probiotics for glycaemic modulation in mice and monkeys.

Sustained and controlled delivery of glucose-lowering agents using engineered designer cells is recognized as an effective strategy for diabetes therapy1. However, current technologies rely on external signal control or have been programmed into mammalian cells using synthetic gene networks, which pose safety concerns arising from transplantation2,3. Here we developed an engineered oral-deliverable glucose-sensing and functional response probiotic living drug for 'sense-and-respond'-based control of diabetic blood glucose. We created a glucose sensor based on a synthetic gene circuit that incorporates the glucose-responsive transcriptional regulator HexR, coupled with a synthetic promoter. Upon oral administration of the engineered probiotics carrying the sensor, the cells reside temporarily in the intestine and regulate the expression of therapeutic transgenes in response to glucose levels that exceed the normal threshold. We show efficacy from the engineered probiotics for glycaemic control in multiple diabetic mouse and non-human primate models, demonstrating that long-term oral administration drives clear improvements in lipid profiles, while also attenuating development of multiple diabetic complications. Our probiotics-based living drug enables therapeutic dosing in response to real-time blood glucose levels, providing a programmable, orally deliverable sense-and-respond platform for metabolic therapy without transplantation.

Animals↗

PubMed2006

Potent systemic antitumor immunity induced by vaccination with chemotactic-prostate tumor associated antigen gene-modified tumor cell and blockade of B7-H1.

We previously reported that several DNA fragments from human prostate-specific membrane antigen (hPSM), mouse prostatic acid phosphatase (mPAP), and human prostate-specific antigen (hPSA) genes were selected and fused to create a novel hPSM-mPAP-hPSA fusion gene (named 3P gene), and human secondary lymphoid tissue chemokine (SLC), 3P, and human IgG Fc genes were inserted into pcDNA3.1 to construct a DNA vaccine, designated pSLC-3P-Fc. In this report, to establish a more efficient treatment for immunotherapy against prostate cancer, the construct was transfected into B16F10 to generate gene-modified tumor cell vaccine (named B16F10-SLC-3P-Fc). In poorly immunogenic B16F10 mouse melanoma model, the immunization with B16F10-SLC-3P-Fc resulted in a strong antitumor response and 50% of tumor-bearing mice achieved long-term survival (>120 days). In vivo depletion of lymphocytes indicated that CD8(+) T cells were involved in the direct tumor killing, whereas CD4(+) T lymphocytes were required for the induction of CD8(+) CTL response in B16F10-SLC-3P-Fc-immunized mice. Splenocytes from B16F10-SLC-3P-Fc-immunized mice specifically recognized and lysed PSM, PAP, PSA, and 3P expressing tumor cells. The combined therapy of B16F10-SLC-3P-Fc plus anti-B7-H1 MAbs further enhanced the immune response. Rechallenge experiment showed that a persistent memory response was successfully induced by the combined therapy. These observations suggest pSLC-3P-Fc-modified tumor cells could serve as a vaccine against prostate cancer, and the therapy combined with anti-B7-H1 MAbs further enhanced the antitumor immune response.

Acid Phosphatase↗

PubMed2006

Type III effector diversification via both pathoadaptation and horizontal transfer in response to a coevolutionary arms race.

The concept of the coevolutionary arms race holds a central position in our understanding of pathogen-host interactions. Here we identify the molecular mechanisms and follow the stepwise progression of an arms race in a natural system. We show how the evolution and function of the HopZ family of type III secreted effector proteins carried by the plant pathogen Pseudomonas syringae are influenced by a coevolutionary arms race between pathogen and host. We surveyed 96 isolates of P. syringae and identified three homologs (HopZ1, HopZ2, and HopZ3) distributed among approximately 45% of the strains. All alleles were sequenced and their expression was confirmed. Evolutionary analyses determined that the diverse HopZ1 homologs are ancestral to P. syringae, and have diverged via pathoadaptive mutational changes into three functional and two degenerate forms, while HopZ2 and HopZ3 have been brought into P. syringae via horizontal transfer from other ecologically similar bacteria. A PAML selection analysis revealed that the C terminus of HopZ1 is under strong positive selection. Despite the extensive genetic variation observed in this family, all three homologs have cysteine-protease activity, although their substrate specificity may vary. The introduction of the ancestral hopZ1 allele into strains harboring alternate alleles results in a resistance protein-mediated defense response in their respective hosts, which is not observed with the endogenous allele. These data indicate that the P. syringae HopZ family has undergone allelic diversification via both pathoadaptive mutational changes and horizontal transfer in response to selection imposed by the host defense system. This genetic diversity permits the pathogen to avoid host defenses while still maintaining a virulence-associated protease, thereby allowing it to thrive on its current host, while simultaneously impacting its host range.

Adaptation, Biological↗

PubMed2006

Enhanced antitumor effect against human telomerase reverse transcriptase (hTERT) by vaccination with chemotactic-hTERT gene-modified tumor cell and the combination with anti-4-1BB monoclonal antibodies.

Human telomerase reverse transcriptase (hTERT) represents an attractive target for cancer immunotherapy because hTERT is reactivated in most human tumors. In an attempt to develop an effective vaccine against most human cancers, we constructed chemotactic-hTERT vaccine. Two hTERT fragments encoding multiple cytotoxic T lymphocyte and T helper cell epitopes were fused as a tumor antigen (named Te). The plasmid based DNA vaccine (pCCL21-Te-Fc) was constructed by linking human CCL21 and IgG Fc gene sequences to each end of Te. In poorly immunogenic B16F10 mouse melanoma model, DNA (pCCL21-Te-Fc) vaccination significantly inhibited tumor growth and all of the mice were dead by day 52. The immunization with pCCL21-Te-Fc-modified tumor cells (B16/CCL21-Te-Fc) resulted in a higher antitumor effect than DNA vaccination and 25% of tumor-bearing mice achieved long-term survival (> 120 days). The combined therapy of B16/CCL21-Te-Fc plus anti-4-1BB MAbs further enhanced the immune response, resulting in 75% of tumor-bearing mice achieved long-term survival (> 120 days) in subcutaneous model and few lung nodules in pulmonary metastasis model. Rechallenge experiment showed that a persistent memory response was successfully induced by the combined therapy. In vivo depletion of lymphocytes indicated that CD8+ T cells were essential in the antitumor activity induced by B16/CCL21-Te-Fc plus anti-4-1BB MAbs, whereas NK cells and CD4+ T cells played substantial roles. The CTL activity induced by pCCL21-Te-Fc-transfected PBMCs specifically lysed a variety of human leukocyte antigen-matched and hTERT-positive human tumor cells, suggesting pCCL21-Te-Fc could serve as a vaccine against most human cancers.

4-1BB Ligand↗

PubMed2006

Enhancement of DNA vaccine potency by sandwiching antigen-coding gene between secondary lymphoid tissue chemokine (SLC) and IgG Fc fragment genes.

DNA vaccine has become an attractive approach for generating antigen-specific immunity. Targeting antigens to FcRs for IgG (FcgammaRs) on dendritic cells (DCs) has been demonstrated to enhance antigen presentation. Secondary lymphoid tissue chemokine (SLC) has been shown to increase immune responses not only by promoting coclustering of T cells and DCs in the lymph nodes and spleen but also by regulating their immunogenic potential for the induction of T cell responses. In this study, using HPV 16 E7 as a model antigen, we constructed a chemotactic-antigen plasmid DNA vaccine (pSLC-E7-Fc) by linking SLC and Fc gene sequences to each end of E7 and evaluated its potency of eliciting specific immune response. We found that immunization with pSLC-E7-Fc generated much stronger E7-specific lymphocyte proliferative and cytotoxic T lymphocyte (CTL) responses than control DNA. All the mice receiving pSLC-E7-Fc prophylactic vaccination remained tumor free upon subcutaneous inoculation of TC-1 cells, while those given control DNA all developed tumors. These tumor-free mice were also protected against TC-1 rechallenge. Complete tumor regression with long-term survival occurred in 72% of mice given pSLC-E7-Fc as therapeutic vaccination. In experimental lung metastasis model wherein TC-1 cells were intravenously injected, therapeutic vaccination with pSLC-E7-Fc significantly reduced the number of tumor nodules in the lung. In vivo depletion with antibodies against CD4+or CD8+ T cells both resulted in complete abrogation of the pSLC-E7-Fc-induced immunotherapeutic effect. Our data indicate that the DNA vaccine constructed by the fusion of SLC and IgG Fc fragment genes to antigen-coding gene is an effective approach to induce potent anti-tumor immune response via both CD4+ and CD8+ T cells dependent pathways.

Animals↗

PubMed2006

Enhancement of antitumour immunity by a novel chemotactic antigen DNA vaccine encoding chemokines and multiepitopes of prostate-tumour-associated antigens.

DNA vaccines provide an attractive technology against cancer because of their safety record in humans and ease of construction, testing and manufacture. In this study, several DNA fragments encoding multiple cytotoxic T lymphocyte (CTL) and T helper cell epitopes were selected from human prostate-specific membrane antigen (hPSM), mouse prostatic acid phosphatase (mPAP), and human prostate-specific antigen (hPSA). These DNA fragments were ligated together to form a novel fusion gene, termed the 3P gene. The secondary lymphoid tissue chemokine (SLC), 3P and human immunoglobulin G Fc genes were inserted into pcDNA3.1 to construct a DNA vaccine, designated pSLC-3P-Fc. After vaccination, the DNA is taken up by cells that produce and secrete the SLC-3P-Fc fusion proteins, termed chemotactic antigen (chemo-antigen). The secreted chemo-antigens, in addition to promoting the co-localization of naive, non-polarized memory T cells and dendritic cells, are efficiently captured and processed by dendritic cells via receptor-mediated endocytosis and then cross-presented to both major histocompatibility complex class I and class II in a cognate manner. The results of this study demonstrate that vaccination with pSLC-3P-Fc by gene gun inoculation induced a strong antitumour response in a mouse tumour model, which significantly inhibited tumour growth and prolonged the survival time of the tumour-bearing mice. In vitro, the secreted SLC-3P-Fc fusion protein can attract lymphocytes from human peripheral blood mononuclear cells (PBMC); when human lymphocytes were stimulated by pSLC-3P-Fc-transfected autologous PBMC, CTLs were induced which could specifically kill hPSM-, hPAP-, or hPSA-expressing tumour cells. These observations provide a new vaccine strategy for cancer therapy through promoting the co-localization of lymphocytes and the concomitant enhancement of antigen-specific CD4+ helper and CD8+ cytotoxic T-cell responses against tumour.

Acid Phosphatase↗

PubMed2006

Induction of protective and therapeutic antitumour immunity using a novel tumour-associated antigen-specific DNA vaccine.

DNA vaccination has become an attractive immunization strategy against cancer. However, a major problem of DNA vaccination is its limited potency to be taken up by the antigen-presenting cells. In contrast, loss of immunogenic epitopes of tumour cells has urged the development of vaccines against multiple epitopes. In this study, we developed a novel strategy for the APC to efficiently cross-present a fusion tumour antigen, which contains both MHC class I-restricted and class II-restricted T-cell epitopes from Her-2/neu and p53 in a cognate manner. The N-terminus of the fusion Her-2/neu, p53 protein was linked to the sequence encoding for human secondary lymphoid-tissue chemokine for secretion and chemokinesis, and the C-terminus of the fusion protein was linked to a cell-binding domain of IgG (Fc portion, the cell-binding domain of IgG) for receptor-mediated internalization. Here, we show that the introduction of fused-gene DNA vaccine by gene gun reduced the size of established tumours and prolonged the lifespan of tumour-bearing mice. Results show that this DNA vaccination strategy can broadly enhance the antigen-specific cellular and humoral immune responses. This vaccine is capable of inducing adaptive immunity and may provide a novel, generic design for the development of therapeutic and preventive DNA vaccines.

Animals↗

PubMed2006

Terminal reassortment drives the quantum evolution of type III effectors in bacterial pathogens.

Many bacterial pathogens employ a type III secretion system to deliver type III secreted effectors (T3SEs) into host cells, where they interact directly with host substrates to modulate defense pathways and promote disease. This interaction creates intense selective pressures on these secreted effectors, necessitating rapid evolution to overcome host surveillance systems and defenses. Using computational and evolutionary approaches, we have identified numerous mosaic and truncated T3SEs among animal and plant pathogens. We propose that these secreted virulence genes have evolved through a shuffling process we have called "terminal reassortment." In terminal reassortment, existing T3SE termini are mobilized within the genome, creating random genetic fusions that result in chimeric genes. Up to 32% of T3SE families in species with relatively large and well-characterized T3SE repertoires show evidence of terminal reassortment, as compared to only 7% of non-T3SE families. Terminal reassortment may permit the near instantaneous evolution of new T3SEs and appears responsible for major modifications to effector activity and function. Because this process plays a more significant role in the evolution of T3SEs than non-effectors, it provides insight into the evolutionary origins of T3SEs and may also help explain the rapid emergence of new infectious agents.

Bacterial Proteins↗

PubMed2005

Specific antitumor immune response induced by a novel DNA vaccine composed of multiple CTL and T helper cell epitopes of prostate cancer associated antigens.

The loss of immunogenic epitopes by tumors has urged the development of vaccines against multiple epitopes. Recombinant DNA technologies have opened the possibility to develop multiepitope vaccines in a relatively rapid and efficient way. In this study, several DNA fragments encoding multiple cytotoxic T lymphocyte (CTL) and T helper (Th) cell epitopes were selected from human prostate-specific membrane antigen (hPSM), mouse prostatic acid phosphatase (mPAP), and human prostate-specific antigen (hPSA), These DNA fragments were ligated together to form a novel fusion gene, termed 3P gene. The 3P gene and human IgG Fc gene were inserted into pcDNA3.1 to construct a DNA vaccine designated psig-3P-Fc. Vaccination with psig-3P-Fc by gene gun inoculation induced strong antitumor response in a mouse tumor model, which significantly inhibited tumor growth and prolonged survival time of the tumor-bearing mice. In vitro, when lymphocytes were stimulated by psig-3P-Fc-transfected autologous peripheral blood mononuclear cells (PBMC), CTLs were induced which could specifically kill hPSM-, hPAP-, or hPSA-expressing tumor cells. These observations provide a new vaccine strategy for cancer therapy through concomitant enhancement of antigen specific CD4(+) helper and CD8(+) cytotoxic T-cell responses against tumors.

Animals↗

PubMed2004

Expression of an exogenous 1-aminocyclopropane-1-carboxylate deaminase gene in Sinorhizobium meliloti increases its ability to nodulate alfalfa.

1-Aminocyclopropane-1-carboxylate (ACC) deaminase has been found in various plant growth-promoting rhizobacteria, including rhizobia. This enzyme degrades ACC, the immediate precursor of ethylene, and thus decreases the biosynthesis of ethylene in higher plants. The ACC deaminase of Rhizobium leguminosarum bv. viciae 128C53K was previously reported to be able to enhance nodulation of peas. The ACC deaminase structural gene (acdS) and its upstream regulatory gene, a leucine-responsive regulatory protein (LRP)-like gene (lrpL), from R. leguminosarum bv. viciae 128C53K were introduced into Sinorhizobium meliloti, which does not produce this enzyme, in two different ways: through a plasmid vector and by in situ transposon replacement. The resulting ACC deaminase-producing S. meliloti strains showed 35 to 40% greater efficiency in nodulating Medicago sativa (alfalfa), likely by reducing ethylene production in the host plants. Furthermore, the ACC deaminase-producing S. meliloti strain was more competitive in nodulation than the wild-type strain. We postulate that the increased competitiveness might be related to utilization of ACC as a nutrient within the infection threads.

Base Sequence↗

PubMed2003

Prevalence of 1-aminocyclopropane-1-carboxylate deaminase in Rhizobium spp.

This is the first report documenting the presence of 1-aminocyclopropane-1-carboxylate (ACC) deaminase in Rhizobium. This enzyme, previously found in free-living bacteria, yeast and fungi, degrades ACC, the immediate precursor of ethylene in higher plants. Thirteen different rhizobial strains were examined by Southern hybridization, Western blots and ACC deaminase enzyme assay. Five of them tested positive for ACC deaminase. Induction of the expression of ACC deaminase was examined in one of the positively tested strains, Rhizobium leguminosarum bv. viciae 128C53K. This rhizobial ACC deaminase had a trace basal level of expression without ACC, but could be induced by a concentration of ACC as low as 1 microM. The more ACC added to this Rhizobium the higher the expression level of the ACC deaminase.

Amino Acids, Cyclic↗

PubMed2003

Rhizobium leguminosarum biovar viciae 1-aminocyclopropane-1-carboxylate deaminase promotes nodulation of pea plants.

Ethylene inhibits nodulation in various legumes. In order to investigate strategies employed by Rhizobium to regulate nodulation, the 1-aminocyclopropane-1-carboxylate (ACC) deaminase gene was isolated and characterized from one of the ACC deaminase-producing rhizobia, Rhizobium leguminosarum bv. viciae 128C53K. ACC deaminase degrades ACC, the immediate precursor of ethylene in higher plants. Through the action of this enzyme, ACC deaminase-containing bacteria can reduce ethylene biosynthesis in plants. Insertion mutants with mutations in the rhizobial ACC deaminase gene (acdS) and its regulatory gene, a leucine-responsive regulatory protein-like gene (lrpL), were constructed and tested to determine their abilities to nodulate Pisum sativum L. cv. Sparkle (pea). Both mutants, neither of which synthesized ACC deaminase, showed decreased nodulation efficiency compared to that of the parental strain. Our results suggest that ACC deaminase in R. leguminosarum bv. viciae 128C53K enhances the nodulation of P. sativum L. cv. Sparkle, likely by modulating ethylene levels in the plant roots during the early stages of nodule development. ACC deaminase might be the second described strategy utilized by Rhizobium to promote nodulation by adjusting ethylene levels in legumes.

Carbon-Carbon Lyases↗

PubMed2002

Strategies used by rhizobia to lower plant ethylene levels and increase nodulation.

Agriculture depends heavily on biologically fixed nitrogen from the symbiotic association between rhizobia and plants. Molecular nitrogen is fixed by differentiated forms of rhizobia in nodules located on plant roots. The phytohormone, ethylene, acts as a negative factor in the nodulation process. Recent discoveries suggest several strategies used by rhizobia to reduce the amount of ethylene synthesized by their legume symbionts, decreasing the negative effect of ethylene on nodulation. At least one strain of rhizobia produces rhizobitoxine, an inhibitor of ethylene synthesis. Active 1-aminocyclopropane-1-carboxylate (ACC) deaminase has been detected in a number of other rhizobial strains. This enzyme catalyzes the cleavage of ACC to alpha-ketobutyrate and ammonia. It has been shown that the inhibitory effect of ethylene on plant root elongation can be reduced by the activity of ACC deaminase.

Carbon-Carbon Lyases↗