Biomedical subjects

J Vadolas

Publications and source records attributed to J Vadolas.

10 recordsLinked to original sources

PubMed2002

Gene therapy for inherited lung disorders: an insight into pulmonary defence.

This review summarizes the latest developments in viral and nonviral gene delivery systems to the lung, and the problems that have to be overcome. Gene delivery has the potential to offer effective treatment to patients with life-threatening lung diseases such as cystic fibrosis and alpha(1)-antitrypsin deficiency, and could modify gene-environment relationships in asthma and other respiratory diseases. Phase I clinical trials conducted in the early 1990s showed that in principle gene transfer to the lung was safe. Although the preliminary results gave encouraging laboratory data, gene expression from viral or nonviral gene delivery systems was too inefficient or transient to offer clinical benefit. Initial optimism gave way to the realization that gene therapy to the lung was unlikely to be straightforward. The host innate and acquired immune system, which protects against infection from inhaled bacteria and viruses, represents a major barrier to successful gene transfer to the lung. A better understanding of the immunological barriers which exist in the lung may allow the development of pharmacological and/or immunological agents that modulate the host immune system to allow for a more continuous and regulated level of gene expression following gene transfer.

Drug Delivery Systems↗

PubMed2002

Targeted gene correction in the mdx mouse using short DNA fragments: towards application with bone marrow-derived cells for autologous remodeling of dystrophic muscle.

In muscle, mutant genes can be targeted and corrected directly by intramuscular (i.m.) injection of corrective DNA, or by ex vivo delivery of DNA to myogenic cells, followed by cell transplantation. Short fragment homologous replacement (SFHR) has been used to repair the exon 23 nonsense transition at the Xp21.1 dys locus in cultured cells and also, directly in tibialis anterior from male mdx mice. Whilst mdx dys locus correction can be achieved in up to 20% of cells in culture, much lower efficiency is evident by i.m. injection. The major consideration for application of targeted gene correction to muscle is delivery throughout relevant tissues. Systemically injected bone marrow (BM)-derived cells from wt C57BL/10 ScSn mice are known to remodel mdx muscle when injected into the systemic route. Provided that non muscle-derived cell types most capable of muscle remodeling activity can be more specifically identified, isolated and expanded, cell therapy seems presently the most favorable vehicle by which to deliver gene correction throughout muscle tissues. Using wt bone marrow as a model, this study investigates systemic application of bone marrow-derived cells as potential vehicles to deliver corrected (ie wt) dys locus to dystrophic muscle. Intravenous (i.v.) and intraperitoneal (i.p.) injections of wt BM were given to lethally and sub-lethally irradiated mdx mice. Despite both i.v. and surviving i.p. groups containing wt dys loci in 100% and less than 1% of peripheral blood nuclei, respectively, both groups displayed equivalent levels of wt dys transcript in muscle RNA. These results suggest that the muscle remodeling activity observed in systemically injected BM cells is not likely to be found in the hemopoietic fraction.

Animals↗

PubMed2000

Engineering EGFP reporter constructs into a 200 kb human beta-globin BAC clone using GET Recombination.

GET Recombination, a simple inducible homologous recombination system for Escherichia coli, was used to target insertion of an EGFP cassette between the start and termination codons of the beta-globin gene in a 200 kb BAC clone. The high degree of homology between the promoter regions of the beta- and delta-globin genes also allowed the simultaneous generation of a delta-globin reporter construct with the deletion of 8.8 kb of intervening sequences. Both constructs expressed EGFP after transient transfection of MEL cells. Similarly, targeting of the EGFP cassette between the promoter regions of the gamma-globin genes and the termination codon of the beta-globin gene enabled the generation of reporter constructs for both (A)gamma- and (G)gamma-globin genes, involving specific deletions of 24 and 29 kb of genomic sequence, respectively. Finally the EGFP cassette was also inserted between the epsilon- and beta-globin genes, with the simultaneous deletion of 44 kb of intervening sequence. The modified constructs were generated at high efficiency, illustrating the usefulness of GET Recombination to generate large deletions of specific sequences in BACs for functional studies. The establishment of stable erythropoietic cell lines with these globin constructs will facilitate the search for therapeutic agents that modify the expression of the individual globin genes in a physiologically relevant manner.

Cloning, Molecular↗

PubMed1998

The role of macrophages in the induction and regulation of immunity elicited by exogenous antigens.

Different delivery vehicles may target to different antigen presenting cells (APC) because of their composition, size and/or physical properties. In this study, we examined the priming of cytotoxic T lymphocyte (CTL) responses to a soluble exogenous protein in vivo, using various delivery vehicles. In addition, we determined the role of macrophages as APC in vivo for each of these delivery vehicles by comparing the induction of antigen-specific CTL and serum antibodies in normal and macrophage-depleted mice. Influenza A virus-derived virosomes, liposomes and monophosphoryl lipid A/squalene (MPLSQ) efficiently induced antigen-specific CTL as well as antibody responses, of which virosomes proved to be the most efficient inducers. In mice that were immunized with cell-associated antigen, strong CTL responses but no antigen-specific antibodies were detectable, while aluminium hydroxide and aluminium phosphate elicited antigen-specific antibodies but no CTL responses. Elimination of macrophages in vivo before immunization abrogated CTL responses induced with liposomes and MPL/SQ, but did not affect induction of antigen-specific CTL with virosomes or cell-associated antigen. Importantly, serum antibody levels were not altered after macrophage depletion, regardless of the delivery vehicle used, suggesting that in the absence of macrophages, other APC may phagocytose the exogenous antigens for major histocompatibility complex (MHC) class II processing and presentation. These results suggest that soluble exogenous antigens delivered in different carrier systems may be processed differently by different APC in vivo for MHC class I- or class II-restricted presentation.

Adjuvants, Immunologic↗

PubMed1998

Intranasal immunization with yeast-expressed 19 kD carboxyl-terminal fragment of Plasmodium yoelii merozoite surface protein-1 (yMSP119) induces protective immunity to blood stage malaria infection in mice.

Variable protection against malaria blood-stage infection has been demonstrated in mice following parenteral immunization with the highly conserved 19 kD carboxylterminal fragment of the merozoite surface protein-1 (MSP119) using CFA/IFA and other adjuvants. Here we show that intranasal immunization of BALB/C mice with yeast expressed Plasmodium yoelii MSP119 plus a mixture of native and recombinant cholera toxin B subunit, could induce serum MSP119-specific antibodies at titres ranging from 20 000 to 2 560 000. The Ig subclass responses were predominantly G1 and G2b. Intranasal immunization led to protection following challenge (peak parasitaemia < 1%) in mice with the highest MSP119-specific titre (>/= 640 000). In two of the three protected mice, a peak parasitaemia of 0.1%-1% was followed by a boost of the antibody response whereas one of the three protected mice did not boost its antibody response after a peak parasitaemia of 0.02%. In unprotected mice, antibody levels rose, then fell, following the detection of parasites in the peripheral blood. CD4+ T cell-depletion abrogated the ability of the mice to boost their antibody response following challenge. These data demonstrate the potential for intranasal immunization with MSP119 to protect against malaria.

Adjuvants, Immunologic↗

PubMed1997

DNA vaccines for bacterial infections.

DNA vaccines are an exciting development in vaccine technology which may have a special role in preventing viral infections and as 'theracines' for cancer. Their use in preventing bacterial infections has, by comparison, been less well documented. While it is unlikely that traditional, highly successful and cheap vaccines for diseases such as diphtheria will be replaced by DNA vaccines, naked DNA may be particularly appropriate for preventing bacterial infections where cytotoxic T cells confer protection, or where a Th1 type T cell response mediates resistance. For example, DNA vaccines containing different mycobacterial antigens have been shown to inhibit overt infections by Mycobacterium tuberculosis in rodent models. The use of DNA vaccines in bacterial infections may be complicated by fundamental differences between prokaryotic and eukaryotic genes and gene products, including mRNA stability, codon bias, secondary structures surrounding native start sequences and glycosylation. These problems can be solved by re-synthesis of bacterial genes to produce 'new' sequences which are more highly expressed by eukaryotic cells.

Animals↗

PubMed1997

Nucleic acid vaccination of sheep: Use in combination with a conventional adjuvanted vaccine against Taenia ovis.

This report describes the use of a nucleic acid vaccine in a large outbred animal species both alone and in combination with a conventionally adjuvanted vaccine. The gene encoding a host-protective antigen (45W) from the sheep parasite Taenia ovis was cloned into the expression vector pcDNA3 and the resultant plasmid termed pcDNA3-45W. Eleven of 15 sheep injected either intramuscularly or intradermally with pcDNA3-45W mounted a serum antibody response to 45W which for both routes of injection was predominantly IgG1. However, the level of antibody elicited by the nucleic acid vaccine was low and repeated vaccinations did not boost the response. Injection of pcDNA3-45W into animals in which an immune response had previously been generated by vaccination with recombinant 45W using Quil A as adjuvant (rec45W vaccine), did not result in enhanced antibody levels. Initial vaccination with pcDNA3-45W and subsequently with the rec45W vaccine resulted in antibody levels significantly higher (P < 0.05) than those obtained in sheep which had only received the rec45W vaccine. This enhanced antibody response was predominantly of the IgG1 subclass (IgG1 : IgG2, 5 : 1) in animals injected with the nucleic acid vaccine by the i.m. route. Surprisingly, a second rec45W vaccination of these animals led to little or no increase in IgG1 levels and a 10-fold increase in IgG2 resulting in a predominance of 45W-specific IgG2 (IgG1 : IgG2, 0.25 1). These studies revealed that nucleic acid vaccination has efficacy, albeit limited, in the sheep and supports previous investigations which showed that antibody responses elicited by immunization are determined by both the route and mode of antigen delivery.

Adjuvants, Immunologic↗

PubMed1997

Alveolar macrophages regulate the induction of primary cytotoxic T-lymphocyte responses during influenza virus infection.

Virus-specific cytotoxic T lymphocytes (CTL) are thought to be responsible for the eradication of respiratory influenza virus infections by direct cytolysis of virus-infected epithelial cells. In this study, we provide evidence for a role for alveolar macrophages (AM) in the regulation of pulmonary virus-specific CTL responses. Prior to infection with influenza virus, AM were selectively eliminated in vivo with a liposome-mediated depletion technique, and virus-specific CTL activities of lung and mediastinal lymph node (MLN) cells were assayed ex vivo and compared with those for normal mice. AM depletion resulted in increased primary CTL responses and changed the kinetics of the CTL response. Flow cytometric analysis of lung and MLN cells showed that the percentage of CD8+ cells was not altered after AM depletion and that lung cells from AM-depleted mice had an increased capacity to lyse virus-infected cells. Upon restimulation in vitro, virus-specific CTL activity in lung cells of normal mice was similar to that in lung cells of AM-depleted mice. Furthermore, elimination of AM resulted in increased virus titers in the lung, but virus clearance as a function of time was not affected. Our results show that AM regulate virus-specific CTL responses during respiratory influenza virus infection by removing viral particles, by downregulating the priming and activity of CTL in MLN cells, and by inhibiting the expansion of virus-specific CTL in the lung.

Animals↗

PubMed1995

Intranasal immunization with liposomes induces strong mucosal immune responses in mice.

BALB/c mice were immunized intranasally with either soluble ovalbumin (OVA) or OVA entrapped in liposomes. The effect of adding Sigma cholera toxin B subunit (sCT-B), which contained low amounts of cholera holotoxin (CT), or recombinant CT-B (rCT-B) which was free from CT, as mucosal adjuvants was also investigated. The mucosal [lung enzyme-linked immunospot assay (ELISPOT), lung washing] and systemic (serum antibody and spleen ELISPOT) responses of immunized mice to OVA and CT-B were determined. Results showed that soluble OVA and liposome-entrapped OVA were poor inducers of mucosal or systemic responses unless CT-B was added as adjuvant. The types of responses augmented by sCT-B and rCT-B were different. CT-B containing low levels of CT (i.e. sCT-B) boosted both mucosal and systemic IgA and IgG responses, whereas rCT-B only increased IgG responses, unless antigen was entrapped in liposomes. Although rCT-B was unable to adjuvant IgA responses against soluble OVA, it was able to induce IgA responses against itself. These data show that mucosal responses can be increased by addition of CT-B containing low levels of CT to antigen preparations given intranasally, suggesting a direct role for CT-A in isotype switching. Furthermore, the ability of CT-B to adjuvant IgA responses against added antigens and its ability to induce responses against itself appear to be separate phenomena. The results from this study should assist the rational formulation of mucosal vaccines which induce potent mucosal and systemic immune responses.

Administration, Intranasal↗

PubMed1990

Neutralization epitopes of human rhinovirus type 2.

Fourteen neutralizing monoclonal antibodies recognizing human rhinovirus (HRV) type 2 have been used to select a total of 51 virus escape mutants. Cross-resistance analysis of the mutants, together with RNA sequencing and identification of amino acid substitutions, have revealed three neutralization sites on the virus surface. Two of these appear to correspond to the NIm-IA and NIm-II sites described for HRV-type 14, although there are also substantial differences. The third site has not been described previously.

Amino Acids↗