Young C3H mice infected with Toxoplasma gondii are a novel experimental model of communicating hydrocephalus.

The effects of leptomeningeal inflammation on the development of hydrocephalus are less understood than those of obstructing the flow of cerebrospinal fluid (CSF) in animal models. We succeeded in introducing a novel experimental model of hydrocephalus and analysed changes in histopathology and CSF flow in mice infected with an avirulent Fukaya strain of Toxoplasma gondii (T. gondii). Six to 7 week-old male mice were orally inoculated with a brain homogenate containing ten T. gondii cysts. The cerebral ventricles became enlarged in all C3H/HeN and C57BL/6 mice 4 weeks after T. gondii infection, but mildly in BALB/c mice. In addition to the lateral ventricle, the third and fourth ventricles and Sylvian aqueducts were dilated in all mice. Lymphocytes and monocytes infiltrated the subarachnoid space. Indian ink particles required more time to pass from the lateral ventricle to the cervical lymph nodes, although they reached the subarachnoid space. Computed tomography ventriculography demonstrated that the CSF was not obstructed during passage through the ventricular systems, but contrast remained static in the lateral ventricle only in infected mice. These results indicated that the infected mice developed communicating type hydrocephalus without obstructive or mass lesions in the ventricles. The hydrocephalus that arises in mice infected with T. gondii is considered a consequence of leptomeningeal inflammation that blocks CSF circulation at the subarachnoid space, implying that leptomeningeal inflammation is important in other types of hydrocephalus.

Secretory IgA, salivary peroxidase, and catalase-mediated microbicidal activity during hydrogen peroxide catabolism in viridans streptococci: pathogen coaggregation.

Viridans streptococci can kill methicillin-resistant Staphylococcus aureus (MRSA) through the production of hydrogen peroxide (H2O2). However, several hundred viridans streptococci cells are necessary to kill 1 cfu of MRSA. We analyzed the potency of bactericidal and fungicidal effector molecules induced by catabolism of H2O2 in the oral cavity. Secretory IgA (SIgA) and an unidentified salivary component bound Streptococcus sanguinis, a viridans streprococcus, and MRSA into coaggregates. In these coaggregates, salivary peroxidase and the MRSA catalase produced singlet molecular oxygen (1O2) from H2O2 produced by viridans streptococci. SIgA converted 1O2 into ozone, which has potent bactericidal and fungicidal activity. We calculated that <10 cfu of Streptococcus sanguinis were necessary to kill 1 cfu of MRSA in the coaggregate. SIgA, Aspergillus niger catalase, and H2O2 in saliva killed Candida albicans, which is highly resistant to reagent H2O2. Together with indigenous bacteria and innate immunity, SIgA potentially constitutes a novel system that may sustain oral homeostasis.

The measurement of parasite antigen-specific IgE levels using anti-IgE monoclonal antibodies and biotinylated antigens.

We studied and evaluated an ELISA system, using a sandwich method with a monoclonal antibody against the Fc domain of IgE molecules and biotinylated antigens, to detect parasite antigen-specific IgE quantitatively. The specific IgE ELISA titre increases linearly in a dose-dependent manner when the concentration of total IgE in samples is less than 2,000 ng/ml. Sera from IgE-deficient SJA/9 mice infected with Trichinella spiralis failed to give any measurable IgE, suggesting that other classes of immunoglobulins have no effect on this assay. The titre showed a good correlation with PCA titre. A high concentration of the serum from Toxocara canis-infected mice reduced the T. spiralis-specific IgE ELISA titre, suggesting that the ELISA system is influenced by a huge amount of IgE against epitopes different from those of target antigens. This ELISA system can also be applied for detecting other classes or subclasses of antigen-specific immunoglobulins.

Cloning and characterization of a novel gene encoding keratin-like protein from nematode Nippostrongylus brasiliensis.

Nippostrongylus brasiliensis (Nb) is one of the most important parasites in studying Th2 immune response of the host, but little is known about its antigenic structures of the excretory-secretory or structural proteins of the parasite. Here we report cloning and characterization of a novel antigenic gene from cDNA library of Nb adult worm by immunoscreening. The positive clone, KLP-Nb, had an open reading frame of 612 bp that encodes a 203-amino-acid protein and was homologous to 'similar to keratins in a glycine-rich region' of Caenorhabditis elegans. Its expression was confirmed by Northern blotting and IgG enzyme-linked immunosorbent assay. This protein seems to be one of the components of cuticle that covers the nematode body.

Diagnosis of Toxoplasma meningoencephalitis in a non-AIDS patient using PCR.

We report herein a rare case of Toxoplasma gondii meningoencephalitis in a non-AIDS patient. Although T. gondii itself was not detected in nucleated cells in peripheral blood and cerebrospinal fluid under the microscope, the polymerase chain reaction method effectively detected the B1 gene of T. gondii in the cells. A serological examination showed increased levels of the IgG but not the IgM antibody to T. gondii, suggesting reactivation of the infection in the brain.

Mechanism of hypergammaglobulinemia by HIV infection: circulating memory B-cell reduction with plasmacytosis.

The mechanism of hypergammaglobulinemia in patients infected with HIV has remained unclear in spite of the identification of a reduction of CD4+ T cells. The amounts of CD27+ memory B cells were remarkably reduced in the peripheral blood and immunoglobulin (Ig) production was diminished in HIV-infected patients. Some of the freshly isolated patients' T cells expressed the CD70 (CD27 ligand) on the surface and the CD70 expression on both of the CD4+ and CD8+ T cells was greatly enhanced by various stimuli. It was also striking that plasmacytosis was observed in patients' bone marrow. Thus, our findings suggest that CD70 expressed spontaneously or by activation on T cells of HIV-infected patients stimulates memory B cells via CD27 and promotes their differentiation into plasma cells, resulting in the elevation of serum Ig levels and the elimination of circulating memory B cells in HIV-infected patients.

Inhibition of interleukin 5 production with no influence on interleukin 4 production by an anti-allergic drug, tranilast, in Toxocara canis-infected mice.

Tranilast is well-known as a useful drug for allergic diseases. This drug is believed to exhibit its therapeutic effects by inhibiting the release of chemical mediators from mast cells and basophils. Effects of tranilast on T helper type 2 (Th2) cytokine production were investigated in mice infected with Toxocara canis (Tc). Tranilast reduced interleukin (IL)-5 production in a dose-dependent manner but not IL-4 production at all in lung and spleen cells from Tc-infected mice cultured under stimulation with excretory-secretory antigen. Obvious IL-5 mRNA expression was observed at week 1 in the lung alone, and IL-4 mRNA expression was detected at similar levels at weeks 1-6 of infection in both lung and spleen. IL-5 but not IL-4 mRNA expression in the lung was significantly inhibited by daily administration of 100 mg/kg of tranilast for 1 week. This treatment also reduced the serum IL-5 level. Thus, tranilast inhibited IL-5 but not IL-4 production either in vitro or in vivo. The results imply that IL-5 and IL-4 production by Th2 cells may be controlled through different mechanisms.

Costimulatory signal through CD86 is important in Th2 response in Trichinella spiralis infected mice.

In order to study the role of the costimulatory signals in Th2 cytokine production, monoclonal antibodies (mAbs) against cell adhesion molecules (CAMs) were added to cultured cells obtained from the mesenteric lymph nodes (MLNs) of mice infected with Trichinella spiralis, followed by a determination of interleukin (IL)-5 and IL-4 in the culture supernatant. IL-5 production by MLN cells stimulated with somatic antigen was significantly reduced by addition of anti-CD86 but not by anti-CD80 mAb. Combination of anti-CD80 and anti-CD86 mAbs reduced IL-5 production most effectively. IL-4 production induced by anti-CD3 mAb was suppressed only by the addition of anti-CD86 mAb. Blockade of the ICAM-1/LFA-1 and VCAM-1/VLA-4 interactions was less effective on the production of IL-5 and IL-4 than the addition of anti-CD86 mAb alone. In contrast to the in vitro cytokine production, intraperitoneal injection of anti-CD80, anti-CD86 mAb, or both, similarly suppressed the peak of the eosinophilia on day 21. Elevation of somatic antigen-specific IgE and IgG1 levels as well as total IgE was not inhibited by the administration of anti-CD80, anti-CD86 mAb or both. In-vitro and in-vivo effects of CTLA-4 immunoglobulin were similar to those of combined treatment with anti-CD80 and anti-CD86 mAbs. These results suggest that the interaction between antigen-presenting cells and CD4 T cells through CD86 are most important in Th2 response during T. spiralis infection.

Polymorphism in the Dirofilaria immitis immunodominant antigen gene.

Dg2, a gene encoding a 34 kDa immunodominant antigen of Dirofilaria immitis was cloned and demonstrated to be specifically expressed in the larval stage. In this study, a newly constructed genomic DNA library was screened by hybridization with Dg2. One of the resulting positive clones was similar to Dg2 in the structure of its exonic regions but different in number, position, size and sequence of introns. This was designated DgK. Full-length cDNA was isolated using the rapid amplification of cDNA ends (RACE) method to study the transcript corresponding to DgK. Sequence analysis revealed that the mRNA corresponding to DgK is trans-spliced during post-transcriptional processing because the 5' end of the amplified cDNA contains seven nucleotides of the nematode-spliced leader (SL) sequence.

Cloning, expression analysis, and chromosomal localization of a novel butyrophilin-like receptor.

We isolated a cDNA clone which shows a similarity with human butyrophilin from a human colon mucosa cDNA library. The cDNA is 1964 bases long, with one open reading frame encoding a protein of 433 amino acids. The deduced amino acid sequence shows an overall homology of 36.5% with the human butyrophilin protein. This gene is mainly expressed in small intestine, colon, testis, and leukocytes. The chromosomal location of the gene was determined on the chromosome 5q35 region by polymerase chain reaction-based analysis with both a human/rodent monochromosomal hybrid cell panel and a radiation hybrid mapping panel.

Isolation and chromosomal mapping of a novel human gene showing homology to Na+/PO4 cotransporter.

We isolated a cDNA clone which shows a significant similarity with the renal Na+/phosphate cotransporter (NPT) from a human intestine mucosa cDNA library. The cDNA is 2626 bases long, with one open reading frame encoding a protein of 497 amino acids. The deduced amino acids sequence shows an overall homology of 48% with the human renal NPT1 protein. This gene is expressed in intestine, colon, liver, and pancreas. Thus, this gene may code for intestinal type NPT or closely related proteins. The chromosomal location of the gene was determined on the chromosome 6p21.3-p22 region by polymerase chain reaction-based analysis with both a human/rodent mono-chromosomal hybrid cell panel and a radiation hybrid mapping panel.

Effects of monoclonal antibodies to adhesion molecules on eosinophilic myocarditis in Toxocara canis-infected CBA/J mice.

Eosinophilic myocarditis followed by fibrosis of the cardiac muscle was observed in addition to peripheral blood eosinophilia in CBA/J mice infected with Toxocara canis. The infected mice were used as an experimental model of eosinophilic endomyocarditis associated with hypereosinophilic syndrome. Effects of in vivo treatment with MoAbs to adhesion molecules on eosinophilic myocarditis were examined using this experimental model. Expressions of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on endothelial cells of capillaries in myocardium were increased 1 and 2 weeks after infection. Infiltration of very late antigen (VLA)-4+ and/or CD11a+ cells into the cardiac muscles was also observed 1 and 2 weeks after infection. Infiltration of eosinophils into the heart was significantly suppressed by anti-CD18 MoAb and anti-VLA-4 MoAb, and focal fibrosis of the cardiac muscle was also significantly suppressed by combined administration of anti-CD18 and anti-ICAM-1 MoAbs. These results indicate that adhesion molecules may play important roles in eosinophilic myocarditis, and that blockade of interaction between adhesion molecules and their ligands may help to control it.

The role of ICAM-1/LFA-1 and VCAM-1/VLA-4 interactions on T helper 2 cytokine production by lung T cells of Toxocara canis-infected mice.

In order to study the effect of costimulatory signals on T helper type 2 (Th2) cytokine production, monoclonal antibodies (mAb) against cell adhesion molecules (CAM) were added to cells in culture obtained from the lungs of Toxocara canis (Tc)-infected mice followed by the determination of interleukin-5 (IL-5) and IL-4 in the supernatants of the culture. ES-stimulated IL-5 production in the supernatant of total lung cells was reduced by 25% when anti-intercellular adhesion molecule-1 (anti-ICAM-1) mAb, anti-CD11a mAb, or both anti-ICAM-1 and anti-CD11a mAb together were added to the culture. The addition of anti-CD18 mAb had no effects. Anti-vascular cell adhesion molecule-1 (anti-VCAM-1) mAb addition also reduced IL-5 production by 60%, although the addition of anti-very late activation antigen-4 (anti-VLA-4) mAb or both anti-VCAM-1 and anti-VLA-4 mAb together were less effective. In the case of anti-CD3 mAb stimulation, similar effects of mAb to CAM were observed. In contrast, IL-4 production induced by anti-CD3 mAb was reduced more markedly by the addition of either anti-ICAM-1 or anti-CD11a mAb than the combination of anti-VCAM-1 and anti-VLA-4 mAb. Similar effects of mAb to CAM were observed on the production of IL-5 and IL-4 by CD4+ T cells purified using a fluorescence-activated cell sorter. Coincubation with adherent cells was necessary for the significant production of IL-5 and IL-4 by CD4+ T cells. These results suggest that the VCAM-1/VLA-4 interaction is more important for IL-5 production by CD4+ T cells in the lungs of Tc-infected mice, and that the ICAM-1/lymphocyte function-associated antigen-1 interaction is more important for the production of IL-4.

Eosinophilia, IgE production, and cytokine production by lung T cells in surface CD4-deficient mutant mice infected with Toxocara canis.

Mutant mice deficient in CD4+ T cells and their normal and heterozygous littermates were infected with Toxocara canis, and compared for eosinophilia, total and Toxocara-specific immunoglobulin E (IgE) production, and in vitro cytokine production by lung cells. The numbers of eosinophils in the peripheral blood of normal and heterozygous mice peaked on days 10 and 21, although mutant mice showed eosinophilia with a peak on day 10. This indicates that the first peak on day 10 is CD4 independent and the second peak is CD4 dependent. Before infection, the levels of total IgE had no significant difference among the three groups of mice. Total and Toxocara-specific IgE in all genotypes of mice increased after infection, and was the highest in normal mice and the lowest in mutant mice. In vitro production of interleukin (IL)-5 and IL-4 by total lung cells was the highest in normal mice and the lowest in mutant mice. CD4+ and CD4- CD8- T lymphocytes, but not CD8+ T lymphocytes produced IL-5 and IL-4 when incubated with anti-CD3 monoclonal antibody (mAb) and lung-adherent cells. These results indicated that IL-5 and IL-4 were produced mainly by CD4+ cells and partly by CD4- CD8- cells, but not by CD8+ cells. In addition, cytokine production by CD4+ cells was affected by the number of CD4 molecules on their surface.

Marked eosinophilia in interleukin-5 transgenic mice fails to prevent Trichinella spiralis infection.

In order to study the role of eosinophils in the host defense against Trichinella spiralis infection, worm recovery after infection with T. spiralis was compared between interleukin-5 transgenic (IL-5 Tg) mice with a constant high level of peripheral eosinophils and nontransgenic C3H/HeN mice. No significant difference in the recovery of muscle larvae or adult worms in the small intestine, fecundity of female adult worms, or infectivity of newborn larvae was observed between nonimmunized C3H/HeN and IL-5 Tg mice or C3H/HeN and IL-5 Tg mice immunized with somatic antigen of T. spiralis. However, a significant difference was observed in the fecundity of female adult worms and recovery of muscle larvae between nonimmunized and immunized IL-5 Tg mice or C3H/HeN mice. These results demonstrate that having more eosinophils does not improve immunity against the various aspects of T. spiralis infection.

Eosinophilia, parasite burden and lung damage in Toxocara canis infection in C57Bl/6 mice genetically deficient in IL-5.

C57Bl/6 mice genetically deficient in interleukin (IL)-5 (IL-5-/-) and mice with the normal IL-5 gene (IL-5+/+) were infected with embryonated eggs of Toxocara canis. IL-5+/+ mice developed a marked eosinophilia in their peripheral bloods and bone marrows after infection. In contrast, the number of eosinophils at these sites actually decreased during the acute phase of infection in IL-5-/- mice. A smaller number of eosinophils infiltrated the lung, liver, heart and skeletal muscle of infected IL-5-/- mice than those of infected IL-5+/+ mice. Eosinophils were not produced in cultures of bone marrow cells from either IL-5+/+ or IL-5-/- mice which were stimulated with excretory secretory antigen of T. canis larvae. The capacity of cells from the bone marrow to differentiate into eosinophils when stimulated in vitro with recombinant murine IL-5 was the same whether the cells were from IL-5+/+ or IL-5-/- mice. Taken together, these results show that an IL-5-like molecule is not produced by the T. canis larvae and that IL-5 produced by host cells is solely responsible for the eosinophilia in mice infected with this nematode. The number and location of T. canis larvae were not altered in the absence of IL-5. In contrast, lung damage in infected IL-5-/- mice was less extensive than that in infected IL-5+/+ mice, although structures resembling Charcot-Leyden crystals were seen in the lungs of both IL-5+/+ and IL-5-/- mice. These results suggest that eosinophils play a role in the pathology in mice infected with T. canis.

The nucleotide sequence and predicted secondary structure of small subunit (18S) ribosomal RNA from Spirometra erinaceieuropaei.

The nucleotide (nt) sequence of a small subunit (18S) ribosomal RNA gene from the plerocercoid of Spirometra erinaceieuropaei (SEP) was determined. The gene with 2182 bp in length is larger than that of most eukaryotes. Extra nt sequences occur in regions known to be variable (V4 and V7). The predicted secondary structure of the nt positions 679-933 (V4) revealed different helices from that of other eukaryotes. The region between nt positions 1540 and 1749 (V7) was different from that of other eukaryotes, but the secondary structure prediction by computer analysis demonstrated that this part of 18S rRNA sequence from S. erinaceieuropaei may form a single extended helix. Nt that were aligned with those of nine other parasites were used to estimate phylogenetic relationships. The data presented here clearly indicate that S. erinaceieuropaei is closely related to Echinococcus granulosus.

Eosinophilia, IL-5 level and recovery of larvae in IL-5 transgenic mice infected with Toxocara canis.

Eosinophil counts, interleukin 5 (IL-5) concentrations in peripheral blood and larval recovery after infection with Toxocara canis were compared between IL-5 transgenic (Tg) and nontransgenic counterparts, C3H/HeN mice. In Tg mice characterized by a constant high level of peripheral eosinophils, eosinophils in peripheral blood fell to the lowest level on day 4 of a T. canis infection and then returned to the preinfection level on day 14. Serum IL-5 level fell to the lowest level on day 4 of infection, then recovered rapidly and peaked on day 14 postinfection. In contrast, the eosinophil and IL-5 levels in the peripheral blood peaked on days 11 and 7 of infection, respectively in C3H/HeN mice. The degree of eosinophil infiltration into the lung 4 days after infection was far more pronounced in Tg than C3H/HeN mice. The highest number of larvae recovered from the lungs of infected Tg and C3H/HeN mice occurred on day 4 postinfection. Strains of Tg and C3H/ HeN mice vaccinated with excretory and secretory (ES) antigens of T. canis larvae were infected with T. canis and the recovery of larvae on day 21 analysed. There were no significant differences in the mean number of larvae recovered from nonvaccinated Tg and C3H/HeN mice or vaccinated Tg and C3H/HeN mice. However, significant differences were demonstrated in the mean total number of larvae recovered from vaccinated and nonvaccinated Tg or C3H/HeN mice. These results suggest that immunocompetent cells other than eosinophils may play a significant role in the expulsion and killing of T. canis larvae in infected mice.

Eosinophil chemotactic activity in bronchoalveolar lavage fluid obtained from Toxocara canis-infected rats.

We examined eosinophil chemotactic activity (ECA) in bronchoalveolar lavage fluid (BALF) obtained from rats infected with Toxocara canis. For 4 weeks after infection, the number of eosinophils was determined in peripheral blood and BALF. ECA was assayed using a microchemotaxis chamber. Eosinophils in peripheral blood and BALF increased markedly after infection, peaking at 12 days and 2 weeks, respectively. ECA in BALF also increased significantly and peaked 2 weeks after infection. Partial characterization revealed that ECA was heat labile, lipid soluble, and resistant to trypsin digestion. Two ECA peaks were identified by molecular sieve column chromatography: one near the egg albumin marker (MW 45,000) and the other observed after elution with quinacrine (MW 472.9). Treatment with a specific leukotriene (LT) B4 receptor antagonist (ONO-4057), a platelet activating factor (PAF) receptor antagonist (TCV-309), and an anti-interleukin (IL)-5 monoclonal antibody (TB13) significantly reduced the ECA, suggesting that LTB4, PAF, and IL-5 contribute to the accumulation of eosinophils in the lungs of rats infected with T. canis.

Molecular cloning and expression of the gene encoding a cysteine proteinase of Spirometra erinacei.

A cDNA library constructed from plerocercoid of Spirometra erinacei (SEP) was immunoscreened using rabbit anti-plerocercoid proteinase polyclonal antibody. A 1.0-kb cDNA clone encoding a cysteine proteinase composed of 336 amino acids was isolated. The amino acid sequence predicted from the cDNA showed significant homology with human and mouse cathepsin L. N-terminal amino acid sequence of the native cysteine proteinase extracted from SEP was the same as that of mature proteinase predicted from the cloned gene. The gene encoding the proteinase was characterized by Southern and Northern blot analysis using the cDNA as a probe. The proteinase with a molecular mass of 34 kDa was demonstrated in in vitro translation products using anti-proteinase polyclonal antibody. A fusion protein derived from the cDNA synthesized by Escherichia coli (TB1) using the expression vector, pMAL-c2 was identified as an immunodominant antigen by epitope-selection method and had no cross-reactivity with other parasite-infected sera. A genomic DNA library derived from SEP was screened by the colony hybridization technique using the cDNA probe. A gene with 4.5 kb encoding the proteinase was obtained, which comprised three exons and two introns.