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Jianzhu Chen

Publications and source records attributed to Jianzhu Chen.

At least 19 recordsLinked to original sources
PubMed2005

Anti-SARS-CoV immunity induced by a novel CpG oligodeoxynucleotide.

To develop CpG oligodeoxynucleotides (CpG ODNs) based therapy for prevention and treatment of severe acute respiratory syndrome (SARS), we selected a novel CpG ODN (BW001), which displays B-type CpG ODN structure feature at the 5' and A-type CpG ODN structure feature at the 3', and tested for its anti-SARS-CoV activity. We found that the supernatants of human PBMCs stimulated by BW001 significantly protected Vero cells from SARS-CoV infection. BW001 could stimulate human PBMCs and pDCs to secrete high level of IFN-alpha and promote human PBMCs and B cells to proliferate. Furthermore, we demonstrated that BW001 could activate CD19+ B cells and CD56+ NK cells in human PBMCs. In addition, BW001 could enhance NK cytotoxicity and IFN-gamma secretion in human PBMCs. Together, BW001 represents a novel type of CpG ODN and may have potential for the development of treatment and prevention for SARS as well as other viral associated diseases.

Adjuvants, Immunologic↗
PubMed2005

Full deacylation of polyethylenimine dramatically boosts its gene delivery efficiency and specificity to mouse lung.

High-molecular-mass polyethylenimines (PEIs) are widely used vectors for nucleic acid delivery. We found that removal of the residual N-acyl moieties from commercial linear 25-kDa PEI enhanced its plasmid DNA delivery efficiency 21 times in vitro, as well as 10,000 times in mice with a concomitant 1,500-fold enhancement in lung specificity. Several additional linear PEIs were synthesized by acid-catalyzed hydrolysis of poly(2-ethyl-2-oxazoline), yielding the pure polycations. PEI87 and PEI217 exhibited the highest efficiency in vitro: 115-fold and 6-fold above those of the commercial and deacylated PEI25s, respectively; moreover, PEI87 delivered DNA to mouse lung as efficiently as the pure PEI25 but at a lower concentration and with a 200-fold lung specificity. These improvements stem from an increase in the number of protonatable nitrogens, which presumably results in a tighter condensation of plasmid DNA and a better endosomal escape of the PEI/DNA complexes. As a validation of the potential of such linear, fully deacylated PEIs in gene therapy for lung diseases, systemic delivery in mice of the complexes of a short interfering RNA (siRNA) against a model gene, firefly luciferase, and PEI25 or PEI87 afforded a 77% and 93% suppression of the gene expression in the lungs, respectively. Furthermore, a polyplex of a siRNA against the influenza viral nucleocapsid protein gene and PEI87 resulted in a 94% drop of virus titers in the lungs of influenza-infected animals.

Acylation↗
PubMed2005

Cross-linked small polyethylenimines: while still nontoxic, deliver DNA efficiently to mammalian cells in vitro and in vivo.

PURPOSE: Polyethylenimine (PEI) is among the most efficient nonviral gene delivery vectors. Its efficiency and cytotoxicity depend on molecular weight, with the 25-kDa PEI being most efficient but cytotoxic. Smaller PEIs are noncytotoxic but less efficient. Enhancement in gene delivery efficiency with minimal cytotoxicity by cross-linking of small PEIs via potentially biodegradable linkages was explored herein. The hypothesis was that cross-linking would raise the polycation's effective molecular weight and hence the transfection efficiency, while biodegradable linkages would undergo the intracellular breakdown after DNA delivery and hence not lead to cytotoxicity. Toward this goal, we carried out cross-linking of branched 2-kDa PEI and its 1:1 (w/w) mixture with a linear 423-Da PEI via ester- and/or amide-bearing linkages; the in vitro and in vivo gene delivery efficiency, as well as toxicity to mammalian cells, of the resultant cross-linked polycations were investigated. METHODS: The efficiency of the cross-linked PEIs in delivering in vitro a plasmid containing beta-galactosidase gene and their cytotoxicity were investigated in monkey kidney cells (COS-7). Dynamic light scattering was used to compare the relative DNA condensation efficiency of the unmodified and cross-linked PEIs. In vivo gene delivery efficiency was evaluated by intratracheal delivery in mice of the complexes of a luciferase-encoding plasmid and the PEIs and estimating the luciferase expression in the lungs. RESULTS: Cross-linking boosted the gene delivery efficiency of the small PEIs by 40- to 550-fold in vitro; the efficiency of the most potent conjugates even exceeded by an order of magnitude that of the branched 25-kDa PEI. Effective condensation of DNA was evident from the fact that the mean diameter of the complexes of the cross-linked PEIs was some 300 nm with a narrow size distribution, while the complexes of the unmodified small PEIs exhibited a mean size of >700 nm with a very broad size distribution. At concentrations where the 25-kDa PEI resulted in >95% cell death, the conjugates afforded nearly full cell viability. The cross-linked PEIs were 17 to 80 times more efficient than the unmodified ones in vivo; furthermore, their efficiencies were up to twice that of the 25-kDa PEI. CONCLUSIONS: Cross-linking of small PEIs with judiciously designed amide- and ester-bearing linkers boosts their gene delivery efficiency both in vitro and in vivo without increasing the cytotoxicity. The high efficiency is dependent on the nature of the linkages and the PEIs used.

Animals↗
PubMed2005

Polycation-mediated delivery of siRNAs for prophylaxis and treatment of influenza virus infection.

Influenza A virus causes one of the most prevalent infections in humans. In a typical year, 10-20% of the population of the US is infected by influenza virus, resulting in up to 40,000 deaths and 200,000 hospitalisations. Vaccination is the most effective preventative measure that can protect 70-90% of healthy adults aged < 65; however, the protection rate is much lower in those most susceptible to infection, namely infants, the elderly and individuals with weakened immune systems. Although four drugs have been approved by the FDA for use as prophylaxis and/or treatment of influenza, concerns about their side effects and the emergence of drug-resistant viruses persist. RNA interference (RNAi), an emerging method of post transcriptional gene silencing, appears ideal for the prevention and treatment of influenza. RNAi in mammals can be mediated by short interfering RNAs (siRNAs) of approximately 21-27 nucleotides in length. The authors have previously shown that siRNAs specific for conserved regions of the influenza virus genome are potent inhibitors of influenza virus replication in both cell lines and chicken embryos. This review discusses the recent progress in the in vivo inhibition of influenza virus by the delivery of siRNAs mediated by non-viral vectors, and the prospects of this strategy for prophylaxis and treatment of influenza infection in humans.

Animals↗
PubMed2004

Poly-beta amino ester-containing microparticles enhance the activity of nonviral genetic vaccines.

Current nonviral genetic vaccine systems are less effective than viral vaccines, particularly in cancer systems where epitopes can be weakly immunogenic and antigen-presenting cell processing and presentation to T cells is down-regulated. A promising nonviral delivery method for genetic vaccines involves microencapsulation of antigen-encoding DNA, because such particles protect plasmid payloads and target them to phagocytic antigen-presenting cells. However, conventional microparticle formulations composed of poly lactic-co-glycolic acid take too long to release encapsulated payload and fail to induce high levels of target gene expression. Here, we describe a microparticle-based DNA delivery system composed of a degradable, pH-sensitive poly-beta amino ester and poly lactic-co-glycolic acid. These formulations generate an increase of 3-5 orders of magnitude in transfection efficiency and are potent activators of dendritic cells in vitro. When used as vaccines in vivo, these microparticle formulations, unlike conventional formulations, induce antigen-specific rejection of transplanted syngenic tumor cells.

Animals↗
PubMed2004

Use of siRNAs to prevent and treat influenza virus infection.

Influenza virus causes one of the most prevalent infections in humans. In a typical year, 10-20% of the population in the United States are infected by influenza virus, resulting in up to 40,000 deaths. Current vaccines can prevent illness in approximately 70-80% of healthy individuals under age 65, but the protection rate is much lower in those most susceptible to infection, namely infants, the elderly, and immunocompromised individuals. Although four antiviral drugs have been approved in the United States for treatment and/or prophylaxis of influenza, their use is limited because of concerns about side effects, compliance, and the possible emergence of resistant virus. We found that short interfering RNAs (siRNAs) specific for conserved regions of the influenza virus genome are potent inhibitors of influenza virus replication in both cell lines and embryonated chicken eggs. In this review, we discuss the potential value of siRNAs for preventing and treating influenza virus infections in humans and the challenges that have to be overcome to realize their potential.

Animals↗
PubMed2004

Inhibition of influenza virus production in virus-infected mice by RNA interference.

Influenza A virus infection is a major source of morbidity and mortality worldwide. Because the effectiveness of existing vaccines and antiviral drugs is limited, development of new treatment modalities is needed. Here, we show that short interfering RNAs (siRNAs) specific for conserved regions of influenza virus genes can prevent and treat influenza virus infection in mice. Virus production in lungs of infected mice is reduced by siRNAs given either before or after initiating virus infection, by using slow i.v. administration of small volumes containing siRNAs in complexes with a polycation carrier. Similar effects also are observed when mice are given DNA vectors i.v. or intranasally, from which siRNA precursors can be transcribed. Development of delivery systems that may be compatible with human use demonstrates the potential utility of siRNAs for prophylaxis and therapy of influenza virus infections in humans.

Animals↗
PubMed2004

A peptide that antagonizes TCR-mediated reactions with both syngeneic and allogeneic agonists: functional and structural aspects.

We identify and consider some characteristics of a peptide antagonist for the Ag-specific receptor on 2C cells (the 2C TCR). The peptide, GNYSFYAL (called GNY), binds to H-2K(b), and a very high-resolution crystal structure of the GNY-K(b) complex at 1.35 A is described. Although the GNY peptide does not bind to L(d), the potency of GNY-K(b) as an antagonist is evident from its ability to specifically inhibit 2C TCR-mediated reactions to an allogenic agonist complex (QLSPFPFDL-L(d)), as well as to a syngeneic agonist complex (SIYRYYGL-K(b)). The crystal structure and the activities of alanine-substituted peptide variants point to the properties of the peptide P4 side chain and the conformation of the Tyr-P6 side chain as the structural determinants of GNYSFYAL antagonist activity.

Alanine↗
PubMed2004

Competition for self-peptide-MHC complexes and cytokines between naive and memory CD8+ T cells expressing the same or different T cell receptors.

To study competition between naïve and memory T cells, we examined proliferation of adoptively transferred naïve CD8(+) T cells in lymphopenic recipients or recipients containing a clonal population of CD8(+) T cells. We find a hierarchy in the extent of T cell proliferation that appears to correlate with the strength of T cell receptor (TCR)-self-peptide-MHC (pepMHC) interactions. CD8(+) T cells also proliferate in recipients containing a full complement of CD8(+) cells with a different TCR if the transferred T cells experience stronger TCR-self-pepMHC interactions than the resident T cells. Furthermore, CD8(+) T cells proliferate in recipients that contain memory CD8(+) cells with a different TCR, but in this case the relative strengths of TCR-self-pepMHC interactions are not as critical. In contrast, CD8(+) T cells do not proliferate significantly in recipients harboring naïve or memory CD8(+) cells that bear the same TCR as the transferred cells. These results suggest that, among naïve T cells and between naïve and memory T cells, CD8(+) cells having the same TCR compete for both self-pepMHC and cytokines, whereas TCR-different CD8(+) cells compete for cytokines. These competitive relationships probably help maintain the size and TCR diversity of naïve and memory T cell populations required for optimal immune responses.

Adoptive Transfer↗
PubMed2004

Molecularly engineered poly(ortho ester) microspheres for enhanced delivery of DNA vaccines.

Genetic vaccination using plasmid DNA presents a unique opportunity for achieving potent immune responses without the potential limitations of many conventional vaccines. Here we report the design of synthetic biodegradable polymers specifically for enhancing DNA vaccine efficacy in vivo. We molecularly engineered poly(ortho ester) microspheres that are non-toxic to cells, protect DNA from degradation, enable uptake by antigen-presenting cells, and release DNA rapidly in response to phagosomal pH. One type of microsphere of poly(ortho esters) that releases DNA vaccines in synchrony with the natural development of adaptive immunity, elicited distinct primary and secondary humoral and cellular immune responses in mice, and suppressed the growth of tumour cells bearing a model antigen. This polymer microparticulate system could, with further study, have implications for advancing the clinical utility of DNA vaccines as well as other nucleic-acid-based therapeutics against viral infections and cancer.

Adjuvants, Immunologic↗
PubMed2004

B cell development and immunoglobulin transcription in Oct-1-deficient mice.

The POU domain transcription factors Oct-1 and Oct-2 interact with the octamer element, a motif conserved within Ig promoters and enhancers, and mediate transcription from the Ig loci. Inactivation of Oct-2 by gene targeting results in normal B cell development and Ig transcription. To study the role of Oct-1 in these processes, the lymphoid compartment of RAG-1(-/-) animals was reconstituted with Oct-1-deficient fetal liver hematopoietic cells. Recipient mice develop B cells with levels of surface Ig expression comparable with wild type, although at slightly reduced numbers. These B cells transcribe Ig normally, respond to antigenic stimulation, undergo class switching, and use a normal repertoire of light chain variable segments. However, recipient mice show slight reductions in serum IgM and IgA. Thus, the Oct-1 protein is dispensable for B cell development and Ig transcription.

Adoptive Transfer↗
PubMed2004

The T-cell receptor beta variable gene promoter is required for efficient V beta rearrangement but not allelic exclusion.

To investigate the role of promoters in regulating variable gene rearrangement and allelic exclusion, we constructed mutant mice in which a 1.2-kb region of the V beta 13 promoter was either deleted (P13(-/-)) or replaced with the simian virus 40 minimal promoter plus five copies of Gal4 DNA sequences (P13(R/R)). In P13(-/-) mice, cleavage, rearrangement, and transcription of V beta 13, but not the flanking V beta gene segments, were significantly inhibited. In P13(R/R) mice, inhibition of V beta 13 rearrangement was less severe and was not associated with any apparent reduction in V beta 13 cleavage. Expression of a T-cell receptor (TCR) transgene blocked cleavages at the normal V beta 13-recombination signal sequence junction and V beta 13 coding joint formation of both wild-type and mutant V beta 13 alleles. However, a low level of aberrant V beta 13 cleavage was consistently detected, especially in TCR transgenic P13(R/R) mice. These findings suggest that the variable gene promoter is required for promoting local recombination accessibility of the associated V beta gene segment. Although the promoter is dispensable for allelic exclusion, it appears to suppress aberrant V beta cleavages during allelic exclusion.

Alleles↗
PubMed2004

Embryonic lethality, decreased erythropoiesis, and defective octamer-dependent promoter activation in Oct-1-deficient mice.

Oct-1 is a sequence-specific DNA binding transcription factor that is believed to regulate a large group of tissue-specific and ubiquitous genes. Both Oct-1 and the related but tissue-restricted Oct-2 protein bind to a DNA sequence termed the octamer motif (5'-ATGCAAAT-3') with equal affinity in vitro. To address the role of Oct-1 in vivo, an Oct-1-deficient mouse strain was generated by gene targeting. Oct-1-deficient embryos died during gestation, frequently appeared anemic, and suffered from a lack of Ter-119-positive erythroid precursor cells. This defect was cell intrinsic. Fibroblasts derived from these embryos displayed a dramatic decrease in Oct-1 DNA binding activity and a lack of octamer-dependent promoter activity in transient transfection assays. Interestingly, several endogenous genes thought to be regulated by Oct-1 showed no change in expression. When crossed to Oct-2(+/-) animals, transheterozygotes were recovered at a very low frequency. These findings suggest a critical role for Oct-1 during development and a stringent gene dosage effect with Oct-2 in mediating postnatal survival.

Animals↗
PubMed2003

The T cell receptor beta enhancer promotes access and pairing of Dbeta and Jbeta gene segments during V(D)J recombination.

The precise function of cis elements in regulating V(D)J recombination is still controversial. Here, we determined the effect of inactivation of the TCRbeta enhancer (Ebeta) on cleavage and rearrangement of Dbeta1, Dbeta2, Jbeta1, and Jbeta2 gene segments in CD4-CD8- [double-negative (DN)] and CD4+CD8+ [double-positive (DP)] thymocytes. In Ebeta-deficient mice, (i) Dbeta1 rearrangements were more severely impaired than Dbeta2 rearrangements; (ii) most of the Dbeta and Jbeta cleavages and rearrangements occurred in DP, rather than in DN, thymocytes; and (iii) most of the 3' Dbeta1 cleavages were coupled to 5' Dbeta2 cleavages instead of to Jbeta cleavages, resulting in nonstandard Dbeta1-Dbeta2-Jbeta2 joints. These findings suggest that the Ebeta regulates TCRbeta rearrangement by promoting accessibility of Dbeta and Jbeta gene segments in DN thymocytes and proper pairing between Dbeta1 and Jbeta gene segments for cleavage and joining in DP thymocytes.

Animals↗
PubMed2003

A B cell-based sensor for rapid identification of pathogens.

We report the use of genetically engineered cells in a pathogen identification sensor. This sensor uses B lymphocytes that have been engineered to emit light within seconds of exposure to specific bacteria and viruses. We demonstrated rapid screening of relevant samples and identification of a variety of pathogens at very low levels. Because of its speed, sensitivity, and specificity, this pathogen identification technology could prove useful for medical diagnostics, biowarfare defense, food- and water-quality monitoring, and other applications.

Aequorin↗
PubMed2003

The resolution of relapsing fever borreliosis requires IgM and is concurrent with expansion of B1b lymphocytes.

The rate of pathogen clearance is a critical determinant of morbidity and mortality. We sought to characterize the immune response responsible for the remarkably rapid clearance of individual episodes of bacteremia caused by the relapsing fever bacterium, Borrelia hermsii. SCID or Rag(-/-) mice were incapable of resolving B. hermsii infection, indicating a critical role for T and/or B cells. TCR(-/-) mice, which lack T cells, and IL-7(-/-) mice, which are deficient in both T cells and follicular B cells, but not in B1 cells and splenic marginal zone (MZ) B cells, efficiently cleared B. hermsii. These findings suggested that B1 cells and/or MZ B cells, two B cell subsets that are known to participate in rapid, T-independent responses, might be involved. The efficient resolution of the episodes of moderate level bacteremia by splenectomized mice suggested that MZ B cells do not play the primary role in clearance of this bacterium. In contrast, xid mice, which are deficient in B1 cells, suffered more severe episodes of bacteremia than wild-type mice. The hypothesis that B1 cells are critical for clearance of B. hermsii was further supported by a selective expansion of the B1b (i.e., IgM(high), IgD(-/low), Mac1(+) CD23(-), and CD5(-)) cell subset in infected xid mice, which coincided with the eventual resolution of infection. Finally, mice selectively incapable of secreting IgM, the dominant isotype produced by B1 cells, were completely unable to clear B. hermsii. Together these results support the model that B1b cells generate the T-independent IgM required for the control and resolution of relapsing fever borreliosis.

Animals↗
PubMed2003

RNA interference of influenza virus production by directly targeting mRNA for degradation and indirectly inhibiting all viral RNA transcription.

Influenza A virus causes widespread infection in the human respiratory tract, but existing vaccines and drug therapy are of limited value. Here we show that short interfering RNAs (siRNAs) specific for conserved regions of the viral genome can potently inhibit influenza virus production in both cell lines and embryonated chicken eggs. The inhibition depends on the presence of a functional antisense strand in the siRNA duplex, suggesting that viral mRNA is the target of RNA interference. However, siRNA specific for nucleocapsid (NP) or a component of the RNA transcriptase (PA) abolished the accumulation of not only the corresponding mRNA but also virion RNA and its complementary RNA. These siRNAs also broadly inhibited the accumulation of other viral, but not cellular, RNAs. The findings reveal that newly synthesized NP and PA proteins are required for influenza virus transcription and replication and provide a basis for the development of siRNAs as prophylaxis and therapy for influenza infection in humans.

Animals↗