Search PubMed⌕ Search

Biomedical subjects

Z Moldoveanu

Publications and source records attributed to Z Moldoveanu.

At least 37 records · Page 2Linked to original sources
PubMed1997

Routes of immunization and antigen delivery systems for optimal mucosal immune responses in humans.

Numerous experiments performed in humans and animals have revealed that stimulation of mucosal lymphoid inductive sites such as intestinal Peyer's patches results in parallel immune responses manifested by the appearance of S-IgA antibodies in the external secretions of remote glands. However, recent experiments suggest that inductive sites associated with the upper respiratory tract, rectum, and perhaps genital tract may also function as sources of lymphoid cells that populate, with some selectivity, certain remote mucosal effector sites. Furthermore, antigen-specific IgA antibodies can be induced in certain secretions (e.g., female genital tract) not only by immunization in the vicinity of corresponding mucosal tissues (e.g., vagina and rectum) but also by oral and especially intranasal immunization. The ineffectiveness of simple delivery of soluble antigens to mucosal membranes for immunization has stimulated extensive studies of strategies for effective delivery systems that would (a) increase the antigen absorption, (b) prevent its degradation, and (c) skew the outcome of immunization to a desired goal (protective response to infectious diseases vs. tolerance; B vs. T cell responses; mucosal vs. systemic). The induction of immune responses at a desired mucosal site can be accentuated with the use of a suitable antigen-delivery system including relevant bacterial or viral vectors, edible transgenic plants expressing microbial antigens, incorporation of antigens in biodegradable microspheres or liposomes, and linkage or coadministration of antigens with cholera toxin B subunit. However, only a few antigen-delivery systems extensively used in animal experimentation have been evaluated for their efficacy in humans. The combination of various immunization routes and the use of suitable antigen-delivery systems may accomplish an important task-the induction of mucosal immune responses at a location relevant to the site of entry of a given pathogen.

Animals↗
PubMed1996

The joining (J) chain is present in invertebrates that do not express immunoglobulins.

Joining (J) chain is a component of polymeric, but not monomeric, immunoglobulin (Ig) molecules and may play a role in their polymerization and transport across epithelial cells. To date, study of the J chain has been confined to vertebrates that produce Ig and in which the J chain displays a considerable degree of structural homology. The role of the J chain in Ig polymerization has been questioned and, since the J chain can be expressed in lymphoid cells that do not produce Ig, it is possible that the J chain may have other functions. To explore this possibility, we have surveyed J-chain gene, mRNA, and protein expression by using reverse transcriptase-coupled PCR, Northern blot analysis, and immunoblot analysis in invertebrate species that do not produce Ig. We report that the J-chain gene is expressed in invertebrates (Mollusca, Annelida, Arthropoda, Echinodermata, and Holothuroidea), as well as in representative vertebrates (Mammalia, Teleostei, Amphibia). Furthermore, J-chain cDNA from the earthworm has a high degree of homology (68-76%) to human, mouse, and bovine J chains. Immunohistochemical studies reveal that the J chain is localized in the mucous cells of body surfaces, intestinal epithelial cells, and macrophage-like cells of the earthworm and slug. This study suggests that the J chain is a primitive polypeptide that arose before the evolution of Ig molecules and remains highly conserved in extent invertebrates and vertebrates.

Animals↗
PubMed1996

Vitamin A deficiency diminishes the salivary immunoglobulin A response and enhances the serum immunoglobulin G response to influenza A virus infection in BALB/c mice.

We examined the effect of vitamin A deficiency on the secretory immunoglobulin (Ig) A and serum IgG response to influenza A virus infections in BALB/c mice. Mice fed a vitamin A-deficient (VAD mice) or a control diet were inoculated with influenza virus at 7 or 9 wk of age when serum retinol concentration had dropped to < or = 0.35 mumol/L in the VAD mice. The influenza-specific salivary IgA response to a mild infection (intranasal inoculation without anesthesia) was not significantly lower in the VAD group (5.3 +/- 2.1% of total IgA 4 wk after infection) than in the control group (10 +/- 11%, P > 0.05). In a separate experiment, this salivary IgA response was significantly lower in the VAD mice (0.3 +/- 0.4% of total IgA) following a more severe infection (intranasal infection while under anesthesia) than it was in control mice (4.2 +/- 4.6% of total IgA, P < 0.0001). In contrast, the concentration of total salivary IgA was uniformly greater in the VAD mice than in the control mice during both the mild infection (VAD, 17 +/- 6 mg/L vs. control, 8 +/- 11 mg/L at 3 wk, P < 0.0001) and the severe infection (VAD, 38 +/- 30 mg/L vs. control, 9 +/- 7 mg/L, P < 0.0001). Similarly, the influenza-specific serum IgG response was also greater in the VAD mice than in the control mice during both the mild infection (VAD, 194 +/- 91 mg/L vs. control, 79 +/- 95 mg/L at 5 wk, P = 0.0002) and the severe infection [VAD median, 202 mg/L (25th, 75th percentiles, 153, 409 mg/L) vs. control, 123 mg/L (42, 165 mg/L), P = 0.0023]. Thus VAD significantly impairs the secretory IgA response to influenza infection but modestly increases the serum IgG response to the same infection.

Animals↗
PubMed1996

Vitamin A deficiency has different effects on immunoglobulin A production and transport during influenza A infection in BALB/c mice.

We examined the effect of advanced vitamin A deficiency (serum retinol < or = 0.35 micromol/L, with weight gain significantly lower than in controls with free access to food) on the secretory immunoglobulin A (IgA) response to a mild, upper respiratory tract infection with influenza A virus in BALB/c mice. Mice fed a vitamin A-deficient or control diet were infected intranasally at 11 to 12 wk of age. The influenza-specific salivary IgA response was lower in the vitamin A-deficient mice (0.11 +/- 0.13% of total IgA 4 wk after infection) than in controls with free access to food (2.73 +/- 1.86%, P < 0.0001). In a separate experiment, the response of vitamin A-deficient mice (0.42 +/- 1.51%) was also lower than that of pair-fed controls (3.43 +/- 4.76%, P < 0.0001). In addition, fewer influenza A-specific IgA-secreting plasma cells were found in the salivary glands of vitamin A-deficient mice (geometric mean 3.0%) than in controls with free access to food or in pair-fed controls (geometric mean 8.7%, P < 0.0001). Although the pathogen-specific IgA response was decreased, vitamin A-deficient mice had a significantly higher concentration of total salivary IgA (31.9 +/- 15.9 mg/L) than did the pair-fed controls (14.3 +/- 8.4 mg/L, P < 0.0001). Northern blot analysis of salivary gland RNA revealed that these vitamin A-deficient mice also had greater levels of mRNA of the polymeric immunoglobulin receptor (pIgR), which transports IgA across mucosal surfaces (plgR: beta-actin mRNA ratio = 7.8 +/- 0.8), than did pair-fed control mice (3.7 +/- 0.4, P = 0.0001). These data demonstrate that vitamin A deficiency has contrasting effects on the secretory IgA response to influenza infection, with a principal effect being a decrease in the pathogen-specific response.

Animals↗
PubMed1996

Salivary, nasal, genital, and systemic antibody responses in monkeys immunized intranasally with a bacterial protein antigen and the Cholera toxin B subunit.

Previous attempts to induce mucosal antibodies in rhesus monkeys by enteric immunization have resulted in only modest and short-lived responses, dominated by immunoglobulin M (IgM) antibodies in the plasma. In this study, two groups of rhesus monkeys were immunized intranasally three times at 2-week intervals with a bacterial protein antigen (AgI/II) either chemically coupled to or mixed with the B subunit of cholera toxin (CT), a known potent mucosal immunogen and carrier for other immunogens. Cells secreting antibodies, predominantly of the IgA isotype, to AgI/II and to CT were detected in the peripheral blood 1 week after each immunization, indicating the dissemination of IgA-secreting precursor cells through the mucosal immune system. IgG and, to a lesser extent, IgA antibodies to both proteins were induced in the plasma commencing after the second immunization. Plasma IgE concentrations and IgE antibody levels were not consistently raised during the immunization period. IgA antibodies were found in nasal and vaginal washes. Nasal IgG but not IgA antibodies showed a significant positive correlation with plasma IgG antibody levels, suggesting that they were largely derived by transudation from the circulation. Analysis of the molecular form of vaginal IgA indicated that both secretory and monomeric forms of IgA were present in various proportions. Furthermore, neither IgG nor IgA antibodies in vaginal washes were correlated with plasma antibody responses, suggesting the contribution of locally synthesized antibodies of both isotypes. Comparison of the responses between the two groups of animals showed only sporadic significant differences, indicating that intranasal immunization with AgI/II either coupled to or mixed with the B subunit of CT was equally effective at inducing generalized IgA antibody responses in the mucosal immune system and predominantly IgG antibodies in the plasma.

Administration, Intranasal↗
PubMed1995

A polarized human endometrial cell line that binds and transports polymeric IgA.

We have demonstrated that a human endometrial cell line, HEC-1, maintains a transepithelial electrical resistance, directionally transports fluids across the cell monolayer, and releases enveloped viruses at distinct plasma membrane domains: influenza virus is released at the apical surfaces and vesicular stomatitis virus (VSV) at the basolateral surfaces. In addition, we have examined the expression of domain-specific endogenous proteins, including the polyimmunoglobulin receptor. Multiple endogenous polypeptides were found to be secreted into the culture medium at basolateral surfaces, whereas no secretion of specific polypeptides was observed from apical cell surfaces. Distinct patterns of endogenous proteins were also observed on apical and basolateral cell surfaces, with a much more complex polypeptide pattern on the basolateral membranes. Using surface biotinylation and immunofluorescence, the polyimmunoglobulin receptor was found to be expressed on the basolateral surface of HEC-1 monolayers. The specific binding of poly-immunoglobulin A (pIgA) was found to occur on the basolateral surface, and was followed by transcytosis to the apical surface and release into the apical medium. The observed characteristics indicate that the endometrium-derived HEC-1 epithelial cell line can be employed as a model for studies of protein transport in polarized epithelial cells of human endometrial tissues, as well as for studies of the interaction of microorganisms with epithelial cells in the genital tract.

Biological Transport↗
PubMed1995

Human immune responses to influenza virus vaccines administered by systemic or mucosal routes.

Healthy adult volunteers were immunized by parenteral or oral routes with trivalent inactivated influenza vaccine (A/Chile/1/83 (H1N1), A/Mississippi/1/85 (H3N2), and B/Ann Arbor/1/86), or intranasally with live attenuated, cold-adapted influenza type A/Texas/1/85 (H1N1) reassortant virus. In all volunteers, cells spontaneously secreting IgA, IgG or IgM antibodies specific to influenza virus were detected in peripheral blood on days 6-13 after immunization, and specific IgA, IgG and IgM antibodies to influenza vaccine were measured in sera and external secretions (saliva and nasal lavage). Following systemic immunization, a raise in specific antibodies of all isotypes was observed in sera beginning on day 13. Although small variations in IgA and IgM antibodies in saliva and nasal lavages were detected, antigen-specific IgG significantly increased between days 13 and 27. Intranasal administration of attenuated virus induced IgA and IgG antibodies in serum as well as in secretions. Serum antibodies were not substantially influenced by oral immunization, only a small increase in all isotypes was observed in volunteers' sera 21 days after ingestion of vaccine. However, in secretions, antigen-specific IgA and IgG responses were detected one week after immunization and reached a peak response on day 20. These studies show that different routes of immunization can be effective for the induction of specific antibodies, and support the concept of the common mucosal immune system in humans by demonstrating that the oral or intranasal administration of antigen-induced specific antibodies of IgA isotype in external secretions, preceded by the transient appearance in peripheral blood of specific antibody-producing cells.

Administration, Intranasal↗
PubMed1995

Immune responses induced by administration of encapsidated poliovirus replicons which express HIV-1 gag and envelope proteins.

Several viruses have been exploited for the development of recombinant vaccine vectors in which to express foreign proteins. Recently, we have described a system utilizing the RNA virus, poliovirus. We have constructed poliovirus genomes in which regions of the capsid have been substituted with gene fragments of the HIV gag and env genes. A complementation system has been designed to encapsidate defective genomes by providing the capsid protein in trans from a recombinant vaccinia virus (VV-P1). Serial passage in the presence of VV-P1 resulted in the generation of stocks of these encapsidated replicons. Infection of cells with these encapsidated replicons resulted in the expression of the recombinant protein as a fusion protein with the poliovirus capsid proteins VP4 and VP1. In this study, we have utilized encapsidated replicons which express the HIV-1-gag capsid protein (p24) as well as 1.5 kb of the HIV-1 env gene. Stocks of these encapsidated replicons were obtained by 20 serial passages in the presence of VV-P1. In addition, passage of the encapsidated replicons in the presence of poliovirus type 2 Lansing resulted in the encapsidation of the replicons by the capsid proteins provided by poliovirus. The administration of the type 2 Lansing/encapsidated replicons expressing HIV-1 gag in BALB/c mice by intramuscular, intrarectal, or intragastric routes resulted in the generation of antibodies in the serum and secretions against both poliovirus and HIV-1 gag. To prove that the replicons alone are immunogenic, we administered replicons expressing either HIV-1 gag or env to transgenic mice which expressed the receptor for poliovirus type 1. Immunization of these mice by the intramuscular route resulted in the generation of serum antibodies specific for poliovirus as well as for HIV-1 antigens. The results obtained led us to the conclusion that the replicons are immunogenic when given alone or in the presence of poliovirus. These results are important for the use of the poliovirus replicons as a recombinant vaccine vector.

AIDS Vaccines↗
PubMed1995

Ig-secreting and interferon-gamma-producing cells in mice mucosally immunized with influenza virus.

1. Oral immunization of mice with influenza virus type A/Udorn, induced antigen-specific IgA antibodies in external secretions (e.g., saliva and fecal extract). 2. Increased numbers of antigen-specific IgA spot-forming cells (SFC) were seen in mononuclear cells isolated from IgA-effector tissues (e.g., SG) of mice orally-immunized with influenza virus. 3. Following oral or systemic immunization of mice, IFN gamma-secreting cells (Th1 type) displayed a characteristic pattern of distribution which was related to the route of immunization.

Administration, Oral↗
PubMed1994

Characterization of poliovirus replicons encoding carcinoembryonic antigen.

Recombinant vaccines hold great promise for the prevention and therapy of infections diseases and cancer. We have explored the use of poliovirus as a recombinant vector to deliver genes into cells for the purpose of vaccination. For our studies, we have chosen to express the gene-encoding carcinoembryonic antigen (CEA) using a novel poliovirus vector. We have constructed a recombinant CEA-poliovirus replicon in which the CEA gene was substituted for the poliovirus capsid gene. Following in vitro transcription, the RNA was transfected into cells to demonstrate CEA expression. We found that a genome in which the region encoding the signal sequence of the CEA protein (amino acids 1-34) was removed was replication competent (i.e., referred to as a replicon). We encapsidated the CEA-poliovirus replicon by transfecting this RNA into cells previously infected with a recombinant vaccinia virus (VV-P1) which expresses the poliovirus capsid protein (P1). Serial passage in the presence of VV-P1 resulted in the generation of stocks of these encapsidated replicons. Infection of cells with the encapsidated replicon containing the CEA-poliovirus genome resulted in expression of the CEA protein. To test immunogenicity, mice susceptible to poliovirus were given three doses of the encapsidated replicons via the i.m. route. By the third administration, a CEA-specific antibody response was detected. Potential future use of the poliovirus replicon system as both a parenteral and oral vaccine vector is discussed.

Amino Acid Sequence↗
PubMed1994

Oral tolerance in humans. T cell but not B cell tolerance after antigen feeding.

The purpose of this study was to investigate whether oral tolerance, defined as Ag-specific immunologic unresponsiveness after Ag feeding, could be induced in humans after prolonged Ag ingestion. Eight adult volunteers ingested a total dose of 0.5 g of keyhole limpet hemocyanin (KLH) followed by subcutaneous immunization with KLH. Eight controls received only the subcutaneous immunization. In the group fed KLH, there was a significant reduction in KLH-specific T cell proliferation (p = 0.04) and delayed skin test responses (p = 0.07) to KLH. KLH ingestion alone did not induce significant levels of Abs in either serum or secretions. However, after the subsequent subcutaneous immunization, the number of circulating IgG and IgM anti-KLH-producing cells, the titers of serum IgG, IgA, and IgM anti-KLH Abs, and the titers of IgA anti-KLH Abs in saliva and intestinal secretions were significantly greater in the KLH-fed group than in the nonfed group. We conclude that KLH feeding induced systemic T cell tolerance, but B cell priming, at both systemic and mucosal sites. These studies support the concept of using Ag feeding as a treatment for certain immune-mediated diseases.

Administration, Oral↗
PubMed1994

Mucosal immunity and strategies for novel microbial vaccines.

Infectious diseases continue to be the leading cause of morbidity and mortality worldwide. Increased awareness of the fact that mucosal membranes are the most frequent portals of entry of pathogenic microorganisms has prompted studies aimed at the development of vaccination protocols and antigen delivery systems that would lead to an increased protection of mucosae. Although systemic and strictly local immunizations are of limited effectiveness in the induction of mucosal protection, ingestion or inhalation of antigens results in a generalized immune response manifested by the appearance of specific antibodies of the secretory immunoglobulin (Ig) isotype in external secretions due to the dissemination of IgA precursor cells from IgA-inductive lymphoid tissues. Furthermore, additional inductive sites strategically positioned at the opening of the respiratory and digestive tracts may also be suitable targets for induction of immune responses at desired effector sites. To prevent degradation and the increase of ingested antigens absorption, novel strategies including enclosure of antigens into biodegradable microspheres, liposomes or their expression in viral and bacterial vectors and plants are currently being considered. Forthcoming technological advances in antigen preparation and routes of delivery will undoubtedly have a profound impact on immunization practices in the future.

Animals↗