Intravenous administration of human embryonic stem cell-derived neural precursor cells attenuates cuprizone-induced central nervous system (CNS) demyelination.

AIMS: Previous studies have demonstrated the therapeutic potential for human embryonic stem cell-derived neural precursor cells (hES-NPCs) in autoimmune and genetic animal models of demyelinating diseases. Herein, we tested whether intravenous (i.v.) administration of hES-NPCs would impact central nervous system (CNS) demyelination in a cuprizone model of demyelination. METHODS: C57Bl/6 mice were fed cuprizone (0.2%) for 2 weeks and then separated into two groups that either received an i.v. injection of hES-NPCs or i.v. administration of media without these cells. After an additional 2 weeks of dietary cuprizone treatment, CNS tissues were analysed for detection of transplanted cells and differences in myelination in the region of the corpus callosum (CC). RESULTS: Cuprizone-induced demyelination in the CC was significantly reduced in mice treated with hES-NPCs compared with cuprizone-treated controls that did not receive stem cells. hES-NPCs were identified within the brain tissues of treated mice and revealed migration of transplanted cells into the CNS. A limited number of human cells were found to express the mature oligodendrocyte marker, O1, or the astrocyte marker, glial fibrillary acidic protein. Reduced apoptosis and attenuated microglial and astrocytic responses were also observed in the CC of hES-NPC-treated mice. CONCLUSIONS: These findings indicated that systemically administered hES-NPCs migrated from circulation into a demyelinated lesion within the CNS and effectively reduced demyelination. Observed reductions in astrocyte and microglial responses, and the benefit of hES-NPC treatment in this model of myelin injury was not obviously accountable to tissue replacement by exogenously administered cells.

Class I MHC can present an endogenous peptide to cytotoxic T lymphocytes.

Since class I MHC glycoproteins may function by "screening and selecting" degraded proteins, we wished to determine whether very short peptides made within a cell were detected and bound by MHC, and presented for T cell perusal. We show that a 22 amino acid viral sequence containing a Db-restricted nonameric CTL epitope is sufficient to direct CTL recognition/lysis of H2b target cells. The mechanism of epitope presentation is by the "natural" endogenous route, and appears to direct lysis as effectively as wild-type virus infection, in which the epitope is part of a 236 residue glycoprotein.

Fine dissection of a nine amino acid glycoprotein epitope, a major determinant recognized by lymphocytic choriomeningitis virus-specific class I-restricted H-2Db cytotoxic T lymphocytes.

We define a nine-amino acid (aa) sequence of VAL-GLU-ASN-PRO-GLY-GLY-TYR-CYS-LEU as a major epitope for immunologic recognition of lymphocytic choriomeningitis virus (LCMV) by H-2b-restricted CTL. The epitope was characterized using molecular genetics to bracket broadly and chemistry to precisely identify aa residues 278-286 of the viral glycoprotein. The epitope's composition is characteristic of a reverse (beta turn) but not an amphipathic alpha helix. A series of peptides with a single aa substitution in position 278 of VAL with other nonpolar (hydrophobic) amino acids (LEU, ILE, ALA, or GLY) coat targets that are recognized and lysed by CTL clones recognizing this epitope. In contrast, substitution of VAL with either large aromatic amino acids (that add bulk: PHE, TYR) or polar side chains (SER, THR) segregates CTL clones normally recognizing aa 278-286 into two groups, one that remains lytic (permissive) despite these changes and another that fails to lyse, indicating CTL can discriminate at a single aa. A change in charge at this position (VAL----ASP or GLU), in general, reduces CTL lysis while a change of VAL to LYS or ASN has minimal affect for four of the five CTL clones analyzed. CTL reactivity with the viral epitope is restricted by the Db but not the Kb of the murine MHC haplotype. A 16-aa peptide of Db that spans alpha 1 residues 37-52 blocks CTL lysis, whereas the corresponding Kb peptide that differs from Db in a single aa in position 50 does not.

Preferential coxsackievirus replication in proliferating/activated cells: implications for virus tropism, persistence, and pathogenesis.

Coxsackieviruses cause substantial human morbidity and mortality, but the underlying molecular mechanisms of disease remain obscure. Here, we review the effects that the cell status--both cellular activation, and the cell cycle--may have on the outcome of virus infection. We propose that these viruses have evolved to undergo productive infection in cells at the G1/S stage of the cell cycle, and to preferentially establish persistence/latent infection in quiescent cells, and we provide possible explanations for these outcomes. Finally, we consider the implications of these interactions for virus transmission and host pathology.

LCMV-specific, class II-restricted cytotoxic T cells in beta 2-microglobulin-deficient mice.

Intracranial infection of normal mice with lymphocytic choriomeningitis virus (LCMV) causes meningitis and death mediated by CD8+ major histocompatibility complex (MHC) class I-restricted cytotoxic T lymphocytes (CTLs). beta 2-Microglobulin-deficient mice (beta 2M-/-) do not express functional MHC class I proteins and do not produce significant numbers of CD8+ T cells. When beta 2M-/- mice were infected with LCMV, many died from LCMV disease and produced a specific response to LCMV mediated by CD4+ CTLs that were class II-restricted. In these mice, CD4+ CTLs may compensate for the lack of CD8+ CTLs.

DNA immunization to prevent autoimmune diabetes.

Mice expressing lymphocytic choriomeningitis virus nucleoprotein (LCMV-NP) as a transgene in their beta cells develop insulin-dependent diabetes mellitus (IDDM) only after LCMV infection. Inoculation of plasmid DNA encoding the insulin B chain reduced the incidence of IDDM by 50% in this model. The insulin B-chain DNA vaccination was effective through induction of regulatory CD4 lymphocytes that react with the insulin B chain, secrete IL-4, and locally reduce activity of LCMV-NP-autoreactive cytotoxic T lymphocytes in the pancreatic draining lymph node. In contrast, similar vaccination with plasmids expressing the LCMV viral ("self") protein did not prevent IDDM, because no such regulatory cells were induced. Thus, DNA immunization with plasmids expressing self-antigens might constitute a novel and attractive therapeutic approach to prevent autoimmune diseases, if the antigens are carefully preelected for an ability to induce regulatory lymphocytes in vivo.

Viruses as triggers of autoimmunity: facts and fantasies.

Autoimmunity has been proposed as the cause of several human chronic inflammatory diseases, and recent animal studies show that viruses can induce autoimmune disease. These studies demonstrate how viruses might misdirect the immune system, and here we discuss critically the evidence that similar phenomena may lead to human disease.

DNA immunization.

Inoculation with plasmid DNA vectors encoding immunogenic proteins induces both humoral and cell-mediated immune responses, which often provide protective immunity. Although many questions regarding the mechanism, efficacy and safety of DNA immunization remain to be addressed, this approach may offer a safer and more cost-effective alternative to conventional vaccines.

Infradian rhythms. A comparison of affective disorders and normal persons.

We matched patients with affective disorders by sex and age with a healthy control group. The two groups recorded daily measures of hours slept, energy, anxiety, and mood levels for 14 months. We analyzed the data using spectral analysis. We found that both groups had statistically significant infradian rhythms, with the majority having seasonal cycles, and that the patients with affective disorders differed from the control subjects in having a greater amplitude of their periodicities.

Clinical implications of dysregulated cytokine production.

Cytokines are soluble proteins that are produced and secreted as part of the immune response to a variety of tissue insults including infection, cancer, and autoimmunity. Most cytokines are secreted by cells of the immune system, but some (for example, type I interferons) are released from "nonimmunological" cells such as fibroblasts and epithelial cells. Cytokines have pleiotropic effects, acting on many somatic cell types to modulate the host's immune response. For the most part, cytokines exert their antimicrobial actions locally---they are secreted by cells in the area of infection, and their effects are restricted to neighboring cells. While many of their local effects benefit the host, cytokines are soluble molecules that may act systemically and are often responsible for many of the symptoms of infection (e.g., headache, fever, myalgia). In high concentrations they can be toxic, or even lethal. Human clinical trials involving the systemic injection of purified cytokines such as interleukins 2 and 12 and tumor necrosis factor alpha provide compelling evidence for the toxicity of these molecules. Likewise, studies of septic shock syndrome demonstrate how overproduction/aberrant production of inflammatory cytokines can lead to rapid mortality. The host may attempt to counter high cytokine levels by releasing soluble cytokine receptors (sCR) or by synthesizing high-affinity anti-cytokine antibodies (acAb), and these natural responses have spawned great interest as potential therapeutic approaches for alleviating cytokine-mediated disease. However, recent studies indicate that these in vivo interactions are much more complex than previously realized; administration of sCR or acAb may either inhibit or (paradoxically) enhance cytokine activity. An alternative therapeutic approach is to intervene at the source of cytokine production. T cells initiate cytokine production only upon antigen contact and terminate synthesis almost immediately after this contact is broken. Thus T cells secrete cytokines specifically at sites of infection and do not continuously produce these potentially toxic molecules while migrating through uninfected tissues or the bloodstream. By learning more about the molecular mechanisms involved with on/off regulation of cytokine production we may be able to develop novel therapeutic drugs to protect against cytokine-mediated immunopathology. This review discusses the regulation of cytokine function by sCR and acAb and compares this to the regulatory mechanisms that are associated with antigen-specific cytokine release by T cells.

Enhancing T cell activation and antiviral protection by introducing the HIV-1 protein transduction domain into a DNA vaccine.

Protein transduction domains (PTD), which can transport proteins or peptides across biological membranes, have been identified in several proteins of viral, invertebrate, and vertebrate origin. Here, we evaluate the immunological and biological consequences of including PTD in synthetic peptides and in DNA vaccines that contain CD8(+) T cell epitopes from lymphocytic choriomeningitis virus (LCMV). Synthetic PTD-peptides did not induce detectable CD8(+) T cell responses. However, fusion of an open reading frame encoding a PTD to an epitope minigene caused transfected tissue culture cells to stimulate epitope-specific T cells much more effectively. Kinetic studies indicated that the epitope reached the surface of transfected cells more rapidly and that the number of transfected cells needed to stimulate T cell responses was reduced by 35- to 50-fold when compared to cells transfected with a standard minigene plasmid. The mechanism underlying the effect of PTD linkage is not clear, but transit of the PTD-attached epitope from transfected cells to nontransfected cells (cross presentation) seemed to play, at most, a minimal role. Mice immunized once with the plasmid encoding the PTD-linked epitope showed a markedly accelerated CD8(+) T cell response and, unlike mice immunized with a standard plasmid, were completely protected against a normally lethal LCMV challenge administered only 8 days post-immunization.

Enhancement of experimental allergic encephalomyelitis (EAE) by DNA immunization with myelin proteolipid protein (PLP) plasmid DNA.

Relapsing-remitting experimental allergic encephalomyelitis (R-EAE) is an animal model for multiple sclerosis (MS). Many potential immunomodulatory strategies for MS have been used first in EAE to assess their effectiveness. Recently, the injection of plasmid DNA has been shown to induce potent humoral and cellular immune responses. The primary aim of our experiments reported here was to determine if vaccination with cDNAs encoding myelin proteolipid protein (PLP) could prime for a PLP-specific immune response and affect subsequent R-EAE. We constructed cDNAs encoding whole PLP (pPLP(all)) or encephalitogenic epitopes PLP(139-151) (pPLP(139-151)) and PLP(178-191) (pPLP(178-191)). Following DNA injection, we induced R-EAE in SJL/J mice using PLP(139-151) or PLP(178-191) peptides in adjuvant. All 3 plasmid constructs enhanced R-EAE induced with PLP(139-151), and injection of mice with pPLP(all) increased R-EAE induced with PLP(178-191). DNA immunization induced higher PLP peptide-specific lymphoproliferative responses than did vector alone following R-EAE induction with IgG1 or IgG2b antibody responses. These data suggest that DNA immunization of PLP can modulate immune responses, leading to enhancement of R-EAE.

Exacerbation of viral and autoimmune animal models for multiple sclerosis by bacterial DNA.

Theiler's murine encephalomyelitis virus (TMEV) infection and relapsing-remitting experimental allergic encephalomyelitis (R-EAE) have been used to investigate the viral and autoimmune etiology of multiple sclerosis (MS), a possible Th1-type mediated disease. DNA immunization is a novel vaccination strategy in which few harmful effects have been reported. Bacterial DNA and oligodeoxynucleotides, which contain CpG motifs, have been reported to enhance immunostimulation. Our objectives were two-fold: first, to ascertain whether plasmid DNA, pCMV, which is widely used as a vector in DNA immunization studies, could exert immunostimulation in vitro; and second, to test if pCMV injection could modulate animal models for MS in vivo. We demonstrated that this bacterially derived DNA could induce interleukin (IL)-12, interferon (IFN)gamma, (Th1-promoting cytokines), and IL-6 production as well as activate NK cells. Following pCMV injections, SJL/J mice were infected with TMEV or challenged with encephalitogenic myelin proteolipid protein (PLP) peptides. pCMV injection exacerbated TMEV-induced demyelinating disease in a dose-dependent manner. Exacerbation of the disease did not correlate with the number of TMEV-antigen positive cells but did with an increase in anti-TMEV antibody. pCMV injection also enhanced R-EAE with increased IFNgamma and IL-6 responses. These results caution the use of DNA vaccination in MS patients and other possible Th1-mediated diseases.

EEG frequency patterns associated with hallucinations in schizophrenia and "creativity" in normals.

This study attempts to define EEG power spectral patterns associated with hallucinatory behaviors in schizophrenia. Six unmedicated schizophrenics with Schneiderian criteria were interviewed and their tongue potentials were monitored and recorded on FM tape. Eye movements and tongue potentials were monitored and segments with artifacts were not used. Consecutive 4-sec intervals of EEG were analyzed in the frequency domain using fast Fourier transorm methods and serial power spectra plots obtained. The intrusiveness of the hallucinatory experience may be similar to the sudden internal experience of perceptual resolution in a creative task. Six normal controls were similarly monitored and analyzed while responding to tests of "creativity." In the 4-sec interval prior to reports of hallucinatory experiences, a frequency pattern of predominatly delta and theta power was found in 71.7% of the EEG segments. In the control group, 78.1% of the EEG segments preceding a creative response demonstrated a similar low frequency pattern which also differed significantly from the base line EEG frequency pattern.

Enhancement of autoimmune disease using recombinant vaccinia virus encoding myelin proteolipid protein.

Viral infections have been associated with the initiation and exacerbations often observed with autoimmune disease. Mechanisms by which viruses may play a role in the development of autoreactive immune responses include polyclonal activation of B and T cells, molecular mimicry, viral infection of immune cells, exposure of sequestered antigens, or altered host cell expression (neoantigen or altered self) in virus infected host cells. We have been studying the immune response generated to self proteins in association with viral infection. Here we evaluate the effects of viral infection on the development of an autoimmune disease of the central nervous system, experimental allergic encephalomyelitis. A vaccinia virus construct, VVplp was made containing the coding region for rat myelin proteolipid protein (PLP). Cells infected with VVplp were found to express PLP protein in vitro. Central nervous system disease was not detectable in mice vaccinated with VVplp. However, mice vaccinated with VVplp and later challenged with encephalitogenic peptides derived from PLP were found to have enhanced disease with earlier onset of symptoms when compared to mice treated with a control vaccinia virus construct. This enhancement of disease was found to peak at 10 days post challenge with the encephalitogenic PLP peptide. Clinical disease and an inflammatory response in the central nervous system was evident in mice previously vaccinated with VVplp but not in control vaccinated mice at this time. These results indicate that prior infection with a virus capable of coding for self protein can predispose the host to an accentuated autoimmune response.

Novel LCMV-specific H-2k restricted CTL clones recognize internal viral gene products and cause CNS disease.

H-2k (C3H/Hej) cytotoxic T lymphocytes (CTL) specific for lymphocytic choriomeningitis virus (LCMV) were cloned. Three clones recognizing internal viral antigens were studied. One such CTL clone recognized neither the glycoprotein nor nucleoprotein encoded by the viral short RNA segment, but reacted with a protein encoded by the long RNA segment, either the viral polymerase, or the Z protein. This one clone, in addition to primary CTL harvested from immunized C3H mice, failed to lyse target cells expressing the Z protein, suggesting recognition was to the viral polymerase. Two other clones recognized the viral nucleoprotein, amino acids 93-100, as determined by protein deletion and peptide mapping studies. When introduced directly into the central nervous systems of LCMV-infected histocompatible mice, all clones were active in vivo and capable of causing immunopathologically mediated death.

Virus encoding an encephalitogenic peptide protects mice from experimental allergic encephalomyelitis.

The association of viral infections with autoimmune central nervous system (CNS) diseases such as post-infectious encephalomyelitis and possibly multiple sclerosis (MS) prompted the investigation to understand how virus infection could modulate autoimmune responses. Recombinant vaccinia viruses encoding an encephalitogenic portion of myelin basic protein (MBP) were evaluated in an animal model for human demyelinating disease, experimental allergic encephalomyelitis (EAE). We have determined that mice vaccinated with recombinant viruses encoding an encephalitogenic region of MBP were protected from EAE. In vivo depletion of CD8+ T cells did not abrogate this protection, suggesting lack of regulation by this cell type. These studies demonstrate that virus infection may be a means to modulated immune responsiveness to CNS disease.

Infection with a recombinant vaccinia virus encoding myelin proteolipid protein causes suppression of chronic relapsing-remitting experimental allergic encephalomyelitis.

Mice infected with a recombinant vaccinia virus (VVplp) encoding the myelin proteolipid protein (PLP) and then challenged with the encephalitogenic peptide, PLP139-151, developed a more severe acute attack vs. control mice. Following this initial acute attack, vaccinated mice had significantly less clinical disease (relapses) than control vaccinated or mock vaccinated mice. Control mice developed a relapsing-remitting disease with severe clinical relapses. During the remission state in VVplp vaccinated mice, histopathologic changes were markedly reduced in the central nervous system (CNS) vs. control vaccinated or unvaccinated mice. Inflammation was mainly limited to the meninges with a reduction of mononuclear cells in the parenchyma of the spinal cord in VVplp vaccinated and PLP139-151 challenged mice vs. control mice where inflammatory changes with demyelination was observed. During the remission period an increase in IL-4 was seen. In addition, there was significantly less T cell proliferation to PLP139-151 that was confirmed by an in vivo measurement of T cell reactivity, DTH responses. This suggests that the almost permanent remission state was dictated by a decreased responsiveness to PLP139-151 in VVplp vaccinated mice.

Limiting the available T cell receptor repertoire modifies acute lymphocytic choriomeningitis virus-induced immunopathology.

The invariably fatal immunopathological disease that follows intracerebral injection of CBA/Ca (H-2k) mice with 1000 PFU of lymphocytic choriomeningitis virus (LCMV) generally fails to develop in congenic mice transgenic for a V beta 8.1D beta 2J beta 2.3C beta 2 T cell receptor (TCR) gene. The majority of these LCMV-infected TCR-transgenic mice show a substantial meningitis of delayed onset, that resolves without causing any obvious clinical impairment. This inflammatory process depends on the involvement of V beta 8+ T cells, but does not require the participation of the CD4+ subset. The cytotoxic effectors that develop in both the transgenic mice and the CBA/Ca controls are lytic for target cells infected with a vaccinia construct expressing genes encoding the putative polymerase protein of LCMV. Limiting the available TCR repertoire to lymphocytes with a single V beta phenotype (not required for the generation of potent effectors in wild-type mice) thus modifies the development of the lethal neuropathology characteristic of LCMV infection, although the CD8+ cytotoxic T lymphocyte response is not greatly compromised.

A rapid and simple method for determining the DNA sequences of fragments inserted into vaccinia virus.

Recombinant virus vectors such as vaccinia virus, adenovirus and herpesvirus are frequently used to express a variety of foreign products. A rapid method allowing the precise identification of recombinants would be useful to confirm the nature of a newly produced recombinant and, in particular, to discriminate between recombinants bearing near-identical foreign products. Using vaccinia virus, we describe a method that in one day provides sequence analysis of the recombinant viral DNA.