The Th1 to Th2 shift induced by Schistosoma mansoni does not exacerbate murine aids (MAIDS)

Schistosoma mansoni infection in mice is associated with a switch from a Th1 to a Th2-type cytokine response. The role of Th1 and Th2 responses in immune dysregulations associated with AIDS and murine AIDS (MAIDS) is controversial, but a Th2 bias could be associated with disease progression, raising the hypothesis that helminth infections might accelerate the retroviral disease progression. Here, we used the murine model of AIDS to evaluate the course of the viral disease during co-infection with S. mansoni. C57BL/6 mice were infected with S. mansoni cercariae 8 weeks before intravenous challenge with the LP-BM5 retroviral complex. MAIDS did not progress faster in co-infected mice, in terms of spleen and inguinal lymphadenopathy size, ecotropic virus titres in the spleen, or in vitro proliferative responses to mitogen. Th2 cytokine production was not enhanced in co-infected animals, except for an isolated increase in IL-4 production 21 weeks after LP-BM5 infection. Co-infected animals had significantly lower lymph node and spleen weights than mice infected with LP-BM5 only. MAIDS did not influence the granulomatous response to S. mansoni in the liver of co-infected mice. Finally, infection with S. mansoni neither enhanced Th2 cytokine production nor accelerated MAIDS progression in animals subsequently challenged with LP-BM5.     

Mycobacterium avium complex infection in mice: lack of exacerbation after LP-BM5 murine leukemia virus infection

The murine leukemia virus LP-BM5 has been used to reproduce the model of murine AIDS in order to evaluate the course of infection with the MO-1 strain of Mycobacterium avium complex (MAC). LP-BM5 was inoculated in C57BL/6 mice by intravenous (i.v.) injection either 8 weeks before an i.v. challenge with 10(3) or 10(6) CFU of MAC (coinfection 1) or 10 days after an i.v. challenge with 10(3) CFU of MAC (coinfection 2). During coinfection 2 experiments, the phenotypic alterations in blood lymphocyte subsets were analyzed. During coinfection 1, LP-BM5 infection tended to decrease the mycobacterial growth, with the difference reaching statistical significance for the lower inoculum (10(3) CFU of MAC) (P<0.001). During coinfection 2, LP-BM5 did not exacerbate MAC infection except in the spleen, at day 90 after LP-BM5 challenge (P<0.001). LP-BM5 infection and the LP-BM5-MAC coinfection increased the numbers of activated CD4+ lymphocytes (CD4+ Ly6AE+) (P<0.001), activated CD8+ lymphocytes (CD8+ Ly6AE+) (P<0.001), and activated B lymphocytes (Ly5+ Ly6AE+) (P<0.001). This activation of T lymphocytes could explain the lack of exacerbation of MAC infection and even the trend to a lower level of MAC infection. Thus, this model of retroviral infection of mice does not seem to be a reliable model of immunodepression for the study of MAC infection and its treatments.     

Glucose-modified low density lipoprotein enhances human monocyte chemotaxis

In response to stimulation with immobilized anti-CD3 antibody, splenocytes from C57BL/6 and BALB/c mice principally produced INF-gamma and IL-4, respectively. However, both splenocytes equally proliferated in response to ConA. We compared the changes after inoculation with BCG (1 mg/mouse) in their capacity to produce IL-4 or IFN-gamma in response to anti-CD3 antibody and to proliferate in response to ConA. Splenocytes from C57BL/6 and BALB/c mice, that had been inoculated with BCG 4 weeks before, produced IFN-gamma with diminished IL-4 production in response to anti-CD3 antibody. Furthermore these splenocytes became anergic to ConA stimulation and died due to cell apoptosis in stead of proliferation. However, we observed the strain difference at 12 weeks after BCG-infection. BCG-primed C57BL/6 splenocytes, that continuously produced IFN-gamma in response to anti-CD3 antibody, failed to proliferate in response to ConA. In contrast, BCG-primed BALB/c splenocytes, that increased IL-4 production but decreased IFN-gamma production when stimulated with anti-CD3 antibody, could proliferate well in response to ConA. Since the splenocytes of BALB/c mice became ConA responsive along with their shifting from Th1 dominant immune response at 4 weeks to Th2 dominant immune response at 12 weeks after BCG-inoculation, IL-4 was assumed to play a crucial role in activation of anergic T cells. Therefore, we stimulated splenocytes from both strains of mice infected with BCG 4 weeks before with ConA in the presence or absence of IL-4. Splenocytes from BCG-infected BALB/c mice showed marked proliferation, while those from BCG-infected C57BL/6 mice failed. We found that IL-4 protected against ConA-induced cell apoptosis in BALB/c splenocytes but not C57BL/6 splenocytes.     

Murine cytomegalovirus-inhibitory effects of ImuVert

ImuVert, a sterile preparation composed primarily of Serratia marcescens membrane vesicles and ribosomes, was significantly inhibitory to murine cytomegalovirus (MCMV) infections in BALB/c mice. Antiviral activity was manifested as increased survivor number and decreased recoverable virus titers in spleens, lungs and salivary glands. Treatments were intraperitoneal (i.p.) beginning 24 h pre, 4 h post- or 24 h post-virus inoculation and then repeated 4 days later. Doses of 5, 16 or 50 micrograms/mouse were effective; 160 micrograms/mouse, which caused host weight loss in toxicity controls, was not inhibitory to the infection. A single i.p. treatment of mice substantially augmented natural killer (NK) cell activity and increased total B-cells, while reducing total T- and T-helper cells. A late (48 h) decline in T-cell function and transient increases in B-cell function were observed in the treated animals. Serum interferon was not induced. Mice pretreated with anti-asialo GM1 antibody to reduce their NK cell populations, then infected with MCMV and treated with ImuVert were protected to the same degree as normal animals. Severe combined immunodeficient mice infected with MCMV and treated with ImuVert were not protected from the infection. These data suggest ImuVert to act by a mechanism other than NK cell activation in preventing MCMV infections.     

Induction of B-cell lymphoma in BALB/c nude mice with an ecotropic, B-tropic helper virus present in the murine AIDS virus stock

The pathogenicities of the murine AIDS (MAIDS) virus complex (LP-BM5) and ecotropic helper virus (BM5eco) isolated from the complex to BALB/c nude mice were studied to elucidate the possible role of replication-competent helper virus in inducing the monoclonal outgrowth of lymphoid cells. Neither LP-BM5 nor BM5eco was pathogenic in adult BALB/c nude mice. However, B-cell lymphoma developed with a very high frequency when either virus was inoculated into newborn BALB/c nude (nu/nu) mice. The cells from the B-cell lymphoma were easily transplanted into nude mice. These results suggested that ecotropic helper virus in the MAIDS virus complex plays an important role in inducing the monoclonal outgrowth of lymphoid cells under immunodeficient conditions caused by defective virus.     

Immunity to porcine rubulavirus infection in adult swine

The immune response against the porcine rubulavirus was analyzed in experimentally infected adult pigs. High titers of virus neutralizing and hemagglutinating inhibitory antibodies were identified in infected animals. The antibody specificity was directed towards HN, M, and NP rubula virion proteins; immunodominance of HN proteins was demonstrated. Peripheral blood mononuclear cells from infected, but not from non-infected pigs proliferated in vitro in response to virus antigenic stimuli, showing a bell-shaped plot with the highest peak at 5 weeks post-infection. Virus-induced lymphoblasts expressed CD4+ CD8+ phenotype, whereas lectin-induced lymphoblasts were mainly identified as CD4+ CD8- cells. Phenotype analysis of freshly prepared PBMC revealed increased number of both monocytes (PoM1+) and total T lymphocytes (CD2+) early during infection, with reduced values of B lymphocytes at 4 weeks post-infection. Decrease in CD4+ CD8- blood cells was observed at 3 weeks post-infection, whereas both CD4- CD8+ and CD4+ CD8+ cells increased 1 and 4 weeks post-infection, respectively. This work discusses the relevance of CD4+ CD8+ T cells in the control of porcine rubulavirus infection.     

Immune response of calves experimentally infected with non-cell-culture-passaged bovine respiratory syncytial virus

The immune response of calves was studied following infection with non-cell-passaged Bovine respiratory syncytial virus (BRSV). Two groups of 6 specific pathogen free (SPF) calves were housed in separate isolation rooms. One group was inoculated intranasally with a non-cell-passaged BRSV strain and the control group was mock-infected. A BRSV specific antibody response was observed for all the BRSV infected calves. These antibodies were shown to have neutralizing activity. No lymphocyte proliferation response was detected in the mock-infected group whereas three animals in the infected group were positive three weeks after the infection. All BRSV-infected calves, except one, produced interferon-gamma (IFN-gamma) one week post-infection and IFN-gamma was observed in all six infected calves after three weeks. The control group showed no IFN-gamma synthesis. In spite of the limits of the BRSV infection model, humoral and cellular immune responses were actively developed by all the calves against this pathogen.     

Psychosocial influences on immune responses to HSV-1 infection in BALB/c mice

The effects of differential housing (one or four mice/cage) on T-helper (Th) cell markers of cellular and humoral immune responses were examined. Differentially housed male BALB/cJ mice were infected with herpes simplex virus (HSV)-1 (Patton strain), and in vitro cytokine production [interleukin (IL)-2, IL-4, IL-10, and interferon (IFN)-gamma] by splenocytes and popliteal lymph node cells and serum antibody titers (IgM and IgG) were evaluated. Differential housing of male BALB/c mice influenced the magnitude, but not the kinetics, of some, but not all, immune responses to HSV-1. Splenocytes from individually housed mice produced more IL-2, IFN-gamma, IL-4, and IL-10 than splenocytes from group-housed mice; in popliteal lymph node cells, only IFN-gamma and IL-10 production was influenced by housing. Although the social environment influenced cytokine production, there were no concomitant changes in circulating IgM or IgG antibody titers. These results do not support the hypothesis that dominant Th cell responses are the primary targets of this psychosocial manipulation, or that a reciprocal relationship exists between Th1 and Th2 cell-derived cytokines.     

Hormone action and chromatin remodelling

In this study, we analyzed the influence of vitamin E succinate (5-80 microM), supplemented in the culture medium, on the survival of cultured retinal cells. The release of lactate dehydrogenase (LDH) was decreased in the presence of low concentrations (10-20 microM) of vitamin E succinate, whereas high concentrations (80 microM) induced a significant increase (about 2-fold) in the release of LDH, indicating a reduction of plasma membrane integrity. Supplementing with vitamin E succinate (80 microM) greatly enhanced its cellular content, as compared to vitamin E acetate (80 microM), and the membrane order of the retinal cells, as evaluated by the fluorescence anisotropy (r) of TMA-DPH (1-(4-(trimethylammonium)-phenyl)-6-phenylhexa-1,3,5-triene), was not altered. Furthermore, vitamin E succinate was more potent than vitamin E acetate in reducing thiobarbituric acid reactive substances (TBARS) formation upon ascorbate-Fe2+-induced oxidative stress (TBARS formation after cell oxidation decreased by about 15-fold or 1.6 fold, respectively, in the presence of 20 microM vitamin E succinate or 20 microM vitamin E acetate). A decrease in MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction induced by supplementing with vitamin E succinate (80 microM), to 35.99 +/- 1.96% as compared to the control, but not by vitamin E acetate (80 microM), suggests that vitamin E succinate may affect the mitochondrial activity. Vitamin E succinate also reduced significantly the ATP:ADP ratio in a dose-dependent manner, indicating that vitamin E succinate-mediated cytotoxic effects involve a decrement of mitochondrial function.     

Nitric oxide synthase expression in macrophages of Histoplasma capsulatum-infected mice is associated with splenocyte apoptosis and unresponsiveness

Splenic macrophages from Histoplasma capsulatum-infected mice express inducible nitric oxide synthase (iNOS), and the iNOS expression correlates with severity of the infection. We examined whether production of NO is responsible for apoptosis and the anti-lymphoproliferative response of splenocytes from mice infected with H. capsulatum. In situ terminal deoxynucleotidyl transferase nick end labeling revealed apoptotic nuclei in cryosections of spleen from infected but not normal mice. Splenocytes of infected mice were unresponsive to stimulation by either concanavalin A or heat-killed H. capsulatum yeast cells. Splenocyte responsiveness was restored by addition to the medium of NG-monomethyl-L-arginine, a known inhibitor of NO production. The proliferative response of splenocytes from infected mice was also restored by depletion of macrophages or by replacement with macrophages from normal mice. In addition, expression of iNOS returned to its basal level when the animals had recovered from infection. These results suggest that suppressor cell activity of macrophages is associated with production of NO, which also appears to be an effector molecule for apoptosis of cultured splenocytes from infected mice.     

Subjective experience and attitudes towards participation in clinical trials among patients with anxiety disorders

Newly recognized rat parvovirus (rat orphan parvovirus: ROPV) was examined for viral excretion and persistence in infected rats, and also for infectivity to mice and hamsters. The virus appeared to replicate mainly in lymphoid or hematopoietic tissues, and was detected in feces, urine and oropharynx of the infected rats at 1 to 4 weeks postinfection. The infective virus was also detected in peripheral leukocytes and various tissues at an acute phase of infection, and decreased in every tissue at 8 weeks postinfection. Viral DNA, however, was persistent in lymphoid tissues at least up to 24 weeks postinfection. When the virus was inoculated to mice and hamsters, no evidence of viral production and antibody response was demonstrated. ROPV is assumed to be a variant of the known rat parvovirus which resulted to alter cell tropism and persist in lymphoid or hematopoietic tissues, in order to escape from host immune system.     

Expression of the myxoma virus tumor necrosis factor receptor homologue and M11L genes is required to prevent virus-induced apoptosis in infected rabbit T lymphocytes

Myxoma virus is a leporipoxvirus that causes a highly lethal virulent disease known as myxomatosis in the European rabbit. An important aspect of myxoma virus pathogenesis is the ability of the virus to productively infect lymphocytes and spread to secondary sites via lymphatic channels. We investigated the infection of the CD4+ T lymphoma cell line RL-5 with myxoma virus and Shope fibroma virus, a related but benign leporipoxvirus, and observed that myxoma virus, but not Shope fibroma virus, was able to productively infect RL-5 cells. We also discovered that infection of RL-5 cells with Shope fibroma virus or attenuated myxoma virus mutants containing disruptions in either the T2 or the M11L gene resulted in the rapid induction of DNA fragmentation, followed by morphological changes and loss in cell integrity characteristic of cell death by apoptosis. Purified exogenous T2 protein was unable to prevent apoptosis, suggesting that T2 functions intracellularly. Thus, myxoma virus T2, originally described as a secreted homologue of the tumor necrosis factor receptor, and M11L, a novel transmembrane species with no known cellular homologue, function to extend virus host range for replication in rabbit T lymphocytes through the inhibition of apoptosis in infected T lymphocytes.     

The control of IL-4 gene expression in activated murine T lymphocytes: a novel role for neu-1 sialidase

IL-4 is important in controlling the development of immune responses. Following activation with anti-CD3epsilon under serum-free conditions, splenocytes from most normal (neu-1b) mouse strains directly produced IL-4 and other T cell cytokines. However, splenic T cells from SM/J and B10.SM (H-2v, neu-1a) strain mice, deficient in neu-1 sialidase activity, failed to produce IL-4 but produced normal levels of IL-2 following activation. Moreover, sialidase-deficient mice produced markedly less IgE and IgG1 Abs following immunization with protein Ags than did mouse strains with normal neu-1 sialidase activity. Enriched T cells from neu-1a mice failed to be effectively primed with exogenous murine IL-4 to become IL-4-producing cells. Treatment of splenocytes or enriched T cells from neu-1a mice with bacterial sialidase prior to activation or IL-4 priming promoted their subsequent capacity to produce IL-4. In contrast, activation of T cells from neu-1b mice in the presence of a sialidase inhibitor almost completely blocked subsequent IL-4 production. The presence of IL-4 during priming enhanced T cell expression of neu-1-specific sialidase activity and increased the membrane expression of asialo-G(M1) compared with T cells activated without IL-4. These results suggest that T cell-associated neu-1 sialidase is required for early IL-4 production by splenic T cells and is involved in the IL-4 priming process of conventional T cells to become active IL-4 producers.     

Early development and progression of lymphocyte-stimulatory cross-reactive idiotypes expressed on antibodies to soluble egg antigens during Schistosoma mansoni infection of mice

Idiotypes (Id) that stimulate immunoregulatory anti-Id T lymphocyte proliferation are expressed on murine and human antibodies (Ab) to soluble egg antigens (SEA) of Schistosoma mansoni. Kinetics of early expression of these stimulatory Id have now been studied using immunoaffinity-purified serum anti-SEA Ab from mice infected with S. mansoni for 6, 7, 8, 12, or 16 weeks. Rabbit anti-Id Ab specific for mouse anti-SEA Id expressed at 8 weeks post-infection (anti-8WkId) demonstrated the strongest interactions with Id present at 7 and 8 weeks post-infection by competitive enzyme-linked immunosorbent assay. Anti-8WkId Ab reacted progressively less well with 12 WkId, 6WkId, and 16WkId. Splenocytes from mice infected for 8 weeks demonstrated the highest blast transformation responses in vitro to anti-SEA Id from mice infected for 6 weeks, while 7, 8, 12, and 16 weeks post-infection Id preparations stimulated progressively less proliferation. These data indicate that although eventual Id-associated immunoregulatory events contribute to chronicity in this disease, production of anti-SEA Ab that express stimulatory cross-reactive immunoregulatory Id comprises a substantial portion of the initial, acute anti-SEA response in mice infected with Schistosoma mansoni. Furthermore, either this particular Id-expressing response is not maintained, or its proportional presence is greatly diminished by the cumulative production of other multiple anti-SEA Ab during the establishment of chronicity, perhaps in response to its immunoregulatory influence very early in infection.     

A study of hepatic mitochondrial respiration and microsomal cytochrome P450 content in mice infected with the liver fluke Fasciola hepatica

Previous studies of the effects of infection of Wistar rats with the common liver fluke, Fasciola hepatica, on liver bioenergetic and drug metabolism have demonstrated a loss of respiratory control in isolated mitochondria and reduced microsomal cytochrome P450 content, respectively, from 2 weeks post-infection throughout the acute phase of the infection. In the present study male Balb/c mice infected with F. hepatica showed a loss of respiratory control in isolated liver mitochondria only at 4 weeks post-infection. A similar time course was demonstrated for a reduction in hepatic microsomal cytochrome P450 content. Preparations from infected CBA mice showed similar changes to Balb/c mice but mitochondrial respiration in preparations from infected Swiss outbred mice was normal. A host difference between strains of mice and between mice and rats is therefore evident in the timing and extent of liver mitochondrial dysfunction and in the timing of the decrease in the cytochrome P450 content of hepatic microsomes. This difference between hosts may be related to the reported differences in cellular inflammatory responses to the migrating juvenile flukes in the livers of rats and mice.     

Extracellular glutamate levels are chronically elevated in the brains of LP-BM5-infected mice: a mechanism of retrovirus-induced encephalopathy

Mice infected with the LP-BM5 leukemia retrovirus mixture develop a progressive immunodeficiency with associated behavioral, histological, and neurochemical alterations consistent with glutamatergic hyperactivation. To gain insight into the contribution of excitatory amino acids to the neurodegeneration observed in these mice, their concentrations were measured in the CSF and striatal microdialysates. Glutamate concentrations were significantly elevated in CSF but not plasma as early as 4 weeks postinoculation. Steady-state glutamate levels in striatal microdialysates were increased threefold and could be reduced 40% by application of L-alpha-aminoadipate, an inhibitor of microglial glutamate transport. Stimulation of infected mice with KCl/L-trans-2,4-pyrrolidine dicarboxylate further increased glutamate levels 170-270% above those evoked in control mice. Tetrodotoxin suppressed the depolarization-evoked increase in glutamate by 88% in control mice, but it had only negligible effects in 40% of infected mice. Analysis of glutamate transport and catabolism suggests that abnormal astrocytic function does not contribute to the increase in basal extracellular glutamate levels. These findings are the first direct evidence that infection with an immunodeficiency-inducing retrovirus leads to a chronic elevation of extracellular free glutamate levels in the brain, which contributes to the neurodegenerative and cognitive deficits observed in these mice.     

The pipette aspiration applied to the local stiffness measurement of soft tissues

The prevalence and development of adult worms in the lungs of mice and gerbils infected with Schistosoma mansoni was investigated. All infected BALB/c mice harbored the schistosomes in their lungs at 10-12 weeks post-infection, showing the distinct relocation of adult worms to the lungs, from the hepatic portal system. The male and female flukes from lungs of BALB/c mice were significantly smaller than those from livers. The percentage of gravid females in lungs was considerably lower than that in the livers. The number of eggs recovered from lungs of BALB/c mice and gerbils having lung female worms, however, was higher than that from animals without lung females, indicating egg deposition of lung females. The number of eggs detected in the brains correlated well with the number of eggs from the lungs in BALB/c and ICR mice. Out of 119 infected gerbils at 8 weeks post-infection, only two animals had egg-emboli in the brain vessels, although many eggs embolized in the lungs of those animals. These data suggest that transfer of worms to the lungs from livers involves reduction of worm recovery from the portal circulation, and also pulmonary pathology of the disease.     

Effective use of ribonucleotide reductase inhibitors (Didox and Trimidox) alone or in combination with didanosine (ddI) to suppress disease progression and increase survival in murine acquired immunodeficiency syndrome (MAIDS)

Ribonucleotide reductase inhibitors (RRIs) have been recently shown to inhibit retroviral replication. We examined a new series of RRIs, 3,4-dihydroxybenzohydroxamic acid (Didox) and 3,4,5-trihydroxybenzohydroxamidoxime (Trimidox) for their ability to alter disease progression in murine acquired immunodeficiency syndrome (MAIDS), both alone and in combination with 2',3'-dideoxyinosine (ddI). MAIDS disease was induced by inoculation of female C57BL/6 mice with the LP-BM5 murine leukemia virus (MuLV) and disease progression characterized by extensive peripheral lymphadenopathy and splenomegaly. Efficacy of treatment with these drugs was based upon their ability to influence survival and disease pathophysiology by monitoring the development of splenomegaly. Toxicity was determined by changes in body weight, total peripheral white blood cell count and hematocrit. Didox or trimidox monotherapy was associated with increased survival and decreased disease pathophysiology, with no apparent toxicity. Combined with ddI, their ability to reduce development of viral induced splenomegaly was enhanced compared to trimidox, didox or ddI alone. These results demonstrate RRIs have potent activity in reversing the disease manifestations characteristic of MAIDS. Further studies are warranted to determine human clinical efficacy.     

T-cell activity associated with secondary infections and implanted cysts of Echinococcus granulosus in BALB/c mice

Selected cytokine profiles of lymphocytes were assessed in BALB/c mice infected with protoscoleces of Echinococcus granulosus. Late stages of the infection (three months+) were characterized by more dominant Th2 activity with elevated IL-4 and IL-10 and reduced IFN-gamma output by Con-A and antigen stimulated splenocytes. Circumparasitic leucocytes produced mainly IL-10 by five months post infection. A peak in IFN-gamma production in the first month of infection may suggest Th1 or Th0 activity at this time and this may be correlated with initial protoscolex death. In addition, cytokine profiles from mice implanted with intact hydatid cysts were also assessed. At two weeks post implantation all cysts were still viable and cytokine production was characterized mainly by elevated IL-10 production. However, at four months post implantation, some of the cysts from two mice had been killed whilst all cysts in the remaining mouse remained viable. In the mice where dead cysts were present, elevated levels of IFN-gamma were detected from splenocytes and circumparasitic cells. Elevated IL-4 was also evident with the splenocytes. In the mouse with viable cysts IFN-gamma production was reduced Results indicate that IFN-gamma(Th1) activity may be correlated with killing of both protoscoleces and established cysts of E. granulosus.