Biomedical subjects

B T Rouse

Publications and source records attributed to B T Rouse.

At least 19 recordsLinked to original sources

PubMed2002

The IL-12 response to herpes simplex virus is mainly a paracrine response of reactive inflammatory cells.

Herpes simplex virus (HSV) infection results in rapid and sustained up-regulation of interleukin (IL)-12, but the primary cellular source of IL-12 after HSV infection is unknown. We demonstrate that this cytokine largely derives from inflammatory cells rather than from productively infected epithelial cells. For optimal IL-12 induction, epithelial cells needed to be infected with replication-competent virus, and cells needed to be able to synthesize proteins. Our results also indicate that HSV-infected cells generate intermediary products that signal recruited inflammatory cells, which themselves were not HSV-infected, to generate IL-12. Possible mechanisms by which infected cells communicate with inflammatory cells to cause IL-12 production are discussed.

Animals↗

PubMed2001

Plasmid DNA encoding CCR7 ligands compensate for dysfunctional CD8+ T cell responses by effects on dendritic cells.

Lymphotoxin alpha-deficient (LTalpha-/-) mice, which lack lymph nodes and possess a disorganized spleen, develop dysfunctional CD8+ T cells upon HSV infection and readily succumb to herpes encephalitis. Such mice do develop apparently normal peptide-specific CD8+ T cell responses, as measured by MHC class I tetramer staining, but the majority of cells fail to become cytotoxic or express peptide-induced IFN-gamma production. In the present study, we demonstrate that functional defects of CD8+ T cells in LTalpha-/- mice can be largely rectified by the administration of plasmid DNA encoding CCR7 ligands before HSV infection. Treated mutant mice developed increased peptide-specific cytotoxic responses, enhanced numbers of CD8+ T cells capable of producing IFN-gamma, as well as improved resistance to HSV challenge. The corrective effect of chemokine treatment appeared to result from improved dendritic cell-mediated Ag presentation. Thus, a major consequence of the treatment was an increase in splenic dendritic cell number in CCR7 ligand-treated LTalpha-/- mice with such splenocyte populations showing improved APC activity in vitro. Our results document that functional defects of CD8+ T cells can be corrected, and indicate the value of plasmid vector encoding appropriate chemokines to achieve such immunotherapy.

Animals↗

PubMed2001

Immunopotentiation of DNA vaccine against herpes simplex virus via co-delivery of plasmid DNA expressing CCR7 ligands.

The CCR7 ligands, secondary lymphoid tissue chemokine (SLC) and Epstein-Barr virus-induced molecule 1 ligand chemokine (ELC), were recently recognized as key molecules in establishing functional microenvironments for the initiation of immune responses in secondary lymphoid tissue. Here, we investigated the effect of CCR7 ligands-DNA administration on systemic and mucosal immune responses to plasmid DNA encoding gB of herpes simplex virus (HSV). Systemic co-transfer of both CCR7 ligands enhanced serum gB-specific IgG Ab but failed to elicit enhancement of distal mucosal IgA responses. In contrast, mucosal co-transfer provided significant increases of distal mucosal IgA responses. CCR7 ligands also enhanced T cell-mediated immunity as measured by CD4+ T helper cell proliferation and CD8+ T cell-mediated CTL activity. Of particular interest, is the observation that SLC significantly increased the production of Th1-type cytokines (IL-2 and IFN-gamma) (P<0.05), whereas ELC increased the production of both Th1-type and Th2-type (IL-4) cytokines (P<0.05). Moreover, co-vaccination of CCR7 ligands increased the number of dendritic cells in secondary lymphoid tissue. These data indicate that CCR7 ligands may prove to be useful adjuvants for genetic vaccination against intracellular infection as well as cancer.

Adjuvants, Immunologic↗

PubMed2001

Bystander activation involving T lymphocytes in herpetic stromal keratitis.

Herpes simplex virus infection of mouse corneas can lead to the development of an immunopathological lesion, termed herpetic stromal keratitis (HSK). Such lesions also occur in TCR-transgenic mice backcrossed to SCID (TgSCID) that are unable to mount detectable HSV-specific immune responses. The present study demonstrates that lesion expression in such mice depends on continuous viral replication, whereas in immunocompetent mice, lesions occurred even if virus replication was terminated at 4 days after infection. The continuous replication in TgSCID mice was considered necessary to produce an activating stimulus to CD4(+) T cells that invade the cornea. Lesions in TgSCID were resistant to control by cyclosporin A, but were inhibited by treatment with rapamycin. This result was interpreted to indicate that T cell activation involved a non-TCR-mediated cytokine-driven bystander mechanism. Bystander activation was also shown to play a role in HSK lesions in immunocompetent mice. Accordingly, in immunocompetent DO11.10 mice, lesions were dominated by KJ1.26(+) OVA-specific CD4(+) T cells that were unreactive with HSV. In addition, KJ1.26(+) HSV nonimmune cells parked in ocularly infected BALB/c mice were demonstrable in HSK lesions. These results provide insight for the choice of new strategies to manage HSK, an important cause of human blindness.

Adoptive Transfer↗

PubMed2001

Prime-boost immunization with DNA vaccine: mucosal route of administration changes the rules.

In this study we assessed prime-boost immunization strategies with a DNA vaccine (gB DNA) and attenuated recombinant vaccinia virus vector (rvacgB), both encoding the gB protein of HSV, for their effectiveness at inducing mucosal as well as systemic immunity to HSV. Confirming the reports of others, systemic priming with gB DNA and systemic boosting with rvacgB were the most effective means of inducing serum Ab and splenic T cell responses. Nevertheless, the systemic prime-boost approach failed to induce detectable humoral or T cell responses at mucosal sites. However, such responses, at both proximal and distal locations, were induced if immunizations, especially the priming dose, were administered mucosally. Curiously, whereas optimal immunity with systemic priming and boosting occurred when gB DNA was used to prime and rvacgB was used as a boost, mucosal responses were optimal when animals were mucosally primed with rvacgB and boosted with gB DNA given mucosally. Furthermore, notable mucosal responses also occurred in animals mucosally primed with rvacgB and subsequently boosted systemically with gB DNA. Because the mucosal prime-boost immunization protocol also induced excellent systemic immune responses, the approach should be useful to vaccinate against agents for which both mucosal and systemic immunity are important for protection.

Administration, Intranasal↗

PubMed2001

Lymphotoxin alpha-/- mice develop functionally impaired CD8+ T cell responses and fail to contain virus infection of the central nervous system.

Recent observations have indicated that viral persistence and tumor spreading could occur because of effector function-defective CD8(+) T cells. Although chronic exposure to Ag, lack of CD4 help, and epitope dominance are suggested to interfere with CTL differentiation, mechanisms underlying the defective effector function remain obscure. We demonstrate in this report that lymphotoxin alpha-deficient mice develop CD8(+) T cells at normal frequencies when infected with HSV or immunized with OVA Ag but show impaired cytotoxic and cytokine-mediated effector functions resulting in enhanced susceptibility to HSV-induced encephalitis. Although these cells display near normal levels of perforin and Fas ligand, they remain largely at a naive state as judged by high expression of CD62 ligand and failure to up-regulate activation or memory markers. In particular, these CD8(+) T cells revealed inadequate expression of the IL-12 receptor, thus establishing a link between CTL differentiation and LTalpha possibly through regulation of IL-12 receptor. Viruses and tumors could evade immunity by targeting the same pathway.

Amino Acid Sequence↗

PubMed2001

Control of stromal keratitis by inhibition of neovascularization.

Stromal keratitis resulting from ocular infection with herpes simplex virus is a common cause of blindness. This report investigates the role of neovascularization in the pathogenesis of stromal keratitis by measuring the outcome of treatment with the potent anti-angiogenesis cytokine endothelial monocyte-activating polypeptide II (EMAP II). We show that systemic and topical administration of EMAP II from the outset of infection resulted in markedly diminished levels of herpes simplex virus-induced angiogenesis and significantly reduced the severity of stromal keratitis lesions. EMAP II treatment had no demonstrable pro-inflammatory or toxic effects and failed to express antiviral activity. The mechanism of action of EMAP II was shown to proceed by causing apoptosis in vascular endothelial cells. Our data document for the first time the essential role of angiogenesis in the pathogenesis of stromal keratitis and also indicate that the therapy of herpetic stromal keratitis could benefit by procedures that diminish angiogenesis.

Angiogenesis Inhibitors↗

PubMed2001

Induction of arginases I and II in cornea during herpes simplex virus infection.

Induction of inducible nitric oxide synthase (iNOS) following corneal infection with herpes simplex virus type-1 (HSV-1) generates nitric oxide (NO), an important player in the defense against viral infection. Changes in arginine metabolism during infection are not limited to effects of iNOS but can also involve arginases, which can modulate NO synthesis and produce ornithine for the generation of polyamines and proline. The latter are important molecules involved in tissue damage and repair during inflammation. In this study we determined the responses of arginase I and II in a murine model of HSV-1-induced stromal keratitis (HSK). In the cornea iNOS and arginase II mRNA were co-induced as the initial inflammation developed at 2 days postinfection (p.i.). As stromal keratitis progressed (days 8-15 p.i.) arginase I mRNA was induced tenfold, in contrast to a moderate decrease in arginase II and a loss of iNOS expression. These results suggest that elevated expression of arginase I and II in the cornea at late stages of ocular HSV-1 infection may play a role in lesion expression in HSK.

Animals↗

PubMed2001

Modulation of immunity against herpes simplex virus infection via mucosal genetic transfer of plasmid DNA encoding chemokines.

In this study, we examined the effects of murine chemokine DNA, as genetic adjuvants given mucosally, on the systemic and distal mucosal immune responses to plasmid DNA encoding gB of herpes simplex virus (HSV) by using the mouse model. The CC chemokines macrophage inflammatory protein 1beta (MIP-1beta) and monocyte chemotactic protein 1 (MCP-1) biased the immunity to the Th2-type pattern as judged by the ratio of immunoglobulin isotypes and interleukin-4 cytokine levels produced by CD4(+) T cells. The CXC chemokine MIP-2 and the CC chemokine MIP-1alpha, however, mounted immune responses of the Th1-type pattern, and such a response rendered recipients more resistant to HSV vaginal infection. In addition, MIP-1alpha appeared to act via the upregulation of antigen-presenting cell (APC) function and the expression of costimulatory molecules (B7-1 and B7-2), whereas MIP-2 enhanced Th1-type CD4(+) T-cell-mediated adaptive immunity by increasing gamma interferon secretion from activated NK cells. Our results emphasize the value of using the mucosal route to administer DNA modulators such as chemokines that function as adjuvants by regulating the activity of innate immunity. Our findings provide new insight into the value of CXC and CC chemokines, which act on different innate cellular components as the linkage signals between innate and adaptive immunity in mucosal DNA vaccination.

Animals↗

PubMed2001

Contribution of vascular endothelial growth factor in the neovascularization process during the pathogenesis of herpetic stromal keratitis.

This report analyzes the role of vascular endothelial growth factor (VEGF)-induced angiogenesis in the immunoinflammatory lesion stromal keratitis induced by ocular infection with herpes simplex virus (HSV). Our results show that infection with replication-competent, but not mutant, viruses results in the expression of VEGF mRNA and protein in the cornea. This a rapid event, with VEGF mRNA detectable by 12 h postinfection (p.i.) and proteins detectable by 24 h p.i. VEGF production occurred both in the virus-infected corneal epithelium and in the underlying stroma, in which viral antigens were undetectable. In the stroma, VEGF was produced by inflammatory cells; these initially were predominantly polymorphonuclear leukocytes (PMN), but at later time points both PMN and macrophage-like cells were VEGF producers. In the epithelium, the major site of VEGF-expressing cells in early infection, the infected cells themselves were usually negative for VEGF. Similarly, in vitro infection studies indicated that the cells which produced VEGF were not those which expressed virus. Attesting to the possible role of VEGF-induced angiogenesis in the pathogenesis of herpetic stromal keratitis were experiments showing that VEGF inhibition with mFlt(1-3)-immunoglobulin G diminished angiogenesis and the severity of lesions after HSV infection. These observations are the first to evaluate VEGF-induced angiogenesis in the pathogenesis of stromal keratitis. Our results indicate that the control of angiogenesis represents a useful adjunct to therapy of herpetic ocular disease, an important cause of human blindness.

Animals↗

PubMed2001

Herpes simplex virus-induced keratitis: evaluation of the role of molecular mimicry in lesion pathogenesis.

Viruses are suspected but usually unproven triggering factors in autoimmunity. One favored mechanism to explain the role of viruses in the genesis of autoimmunity is molecular mimicry. An immunoinflammatory blinding lesion called herpetic stromal keratitis (HSK) that follows ocular infection with herpes simplex virus (HSV) is suggested to result from a CD4(+) T-cell response to a UL6 peptide of HSV that cross-reacts with a corneal autopeptide shared with the immunoglobulin G2a(b) (IgG2a(b)) isotype. The present report reevaluates the molecular mimicry hypothesis to explain HSK pathogenesis. Our results failed to reveal cross-reactivity between the UL6 and IgG2a(b) peptides or between peptide reactive T cells and HSV antigens. More importantly, animals infected with HSV failed to develop responses that reacted with either peptide, and infection with a recombinant vaccinia UL6 vector failed to cause HSK, in spite of generating UL6 reactivity. Other lines of evidence also failed to support the molecular mimicry hypothesis, such as the failure to affect HSK severity upon tolerization of susceptible BALB/c and B-cell-deficient mice with IgG2a(b) or UL6 peptides. An additional study system revealed that HSK could be induced in mouse strains, such as the OT2 x RAG1(-/-) mice (T cell receptor transgenic recognizing OVA(323-339)) that were unable to produce CD4(+) T-cell responses to any detectable HSV antigens. Our results cast doubt on the molecular mimicry hypothesis as an explanation for the pathogenesis of HSK and indicate that if autoimmunity is involved its likely proceeds via a bystander activation mechanism.

Animals↗

PubMed2001

Optimisation of DNA vaccines for the prophylaxis and modulation of herpes simplex virus infections.

Herpes simplex virus (HSV) lacks an effective vaccine. Despite its prevalence and importance HSV infection is not controlled with an acceptable vaccine. Perhaps the best candidate and so far untested approach is the use of plasmid DNA encoding viral proteins. Immunomodulators are also holding some hope as a potential therapeutic. In this review various DNA vaccine approaches used in animal model systems to prevent HSV infections are discussed. Judgements are made as to which of these may prove effective for prophylactic or therapeutic vaccines in humans.

Adjuvants, Immunologic↗

PubMed2001

Immunity to herpes simplex virus: a hypothesis.

This article discusses some possible reasons why people vary in susceptibility to primary infection by herpes simplex virus (HSV), and, in addition, why some individuals suffer lesions upon viral reactivation from latency. An underlying hypothesis is that the effectiveness of various aspects of innate immunity, conditioned by the person's microbial exposure in early life, may affect susceptibility to HSV infection, the nature of the initial adaptive immune response, and the efficacy of the memory-recall reaction following reactivation. Could domicile in a super-sanitized environment result in more troublesome problems with HSV such as is suspected to explain the rising tide of allergy?

Disease Susceptibility↗

PubMed2000

On the mechanisms of T cell silencing by IL-10 DNA: direct and indirect inhibition of T cell functions.

Previously we reported that mucosal IL-10 DNA administration resulted in long-term suppression of virus-induced inflammatory responses by silencing Th1-type CD4+ T cell functions. However, the mechanism by which IL-10 silences the activity of CD4+ T cells was not clear. The present report has shown that mucosal IL-10 DNA administration led to the reduction of reactivity of T cells following TCR stimulation. IL-10 DNA also downregulated APC functions to stimulate T cells but the effect was temporary. Bystander suppression, including that of IL-10 producing regulatory cells, appeared not to be directly involved in the inhibition of T cell reactivity because both anti-IL-10 and anti-IL-10R could not block the suppression of T cell functions. This silenced state could be maintained following adoptive transfer to untreated animals. The nature of the silencing appears to be a reversible anergic state since Ag stimulation in the presence of exogenous IL-2 restored T cell reactivity. Furthermore, IL-10-induced silenced T cells could be induced in vitro by culturing the T cells with rIL-10 in the presence or the absence of antigen stimulation. This state persisted in the absence of rIL-10 and persisted for at least 3 days. A more notable effect, however, was observed when the T cells were incubated with IL-10 in the presence of APC and Ag. These results indicate that IL-10 induced a long-term silenced state in T cells by direct and indirect inhibition of T cell functions.

Adjuvants, Immunologic↗

PubMed2000

Involvement of an ATP-dependent peptide chaperone in cross-presentation after DNA immunization.

Immunization with plasmid DNA holds promise as a vaccination strategy perhaps useful in situations that currently lack vaccines, since the major means of immune induction may differ from more conventional approach. In the present study, we demonstrate that exposure of macrophages to plasmid DNA encoding viral proteins or OVA generates Ag-specific material that, when presented in vitro by dendritic cells to naive T cells, induces primary CTL response or elicits IL-2 production from an OVA peptide-specific T-T hybridoma. The immunogenic material released was proteinaceous in nature, free of apoptotic bodies, and had an apparent m.w. much larger than a 9-11-aa CTL-recognizable peptide. The macrophage-released factor(s) specifically required a hydrolyzable ATP substrate and was inhibited by procedures that removed or hydrolyzed ATP; in addition, anti-heat-shock protein 70 antiserum abrogated the activity to a large extent. These results indicate the possible involvement of a heat-shock protein 70-linked peptide chaperone in a cross-priming method of immune induction by DNA vaccination. Such a cross-priming process may represent a principal mechanism by which plasmid DNA delivered to cells such as myocytes effectively shuttle Ag to DC or other APC to achieve CTL induction in vivo.

Adenosine Triphosphate↗

PubMed2000

Dual role of B cells in mediating innate and acquired immunity to herpes simplex virus infections.

mu-immunoglobulin chain gene targeted B-cell-deficient mice of susceptible BALB/c strain and resistant C57B1/6 strain are up to 100- to 1000-fold more susceptible to cutaneous infection by herpes simplex virus (HSV) than the respective control wild type mice. The effect of the lack of B cells on immunity to HSV infections was analyzed and B cells were found to play a dual role in affecting both innate and acquired immune responses. Natural antibodies (IgM isotype), reactive with HSV have an anti-viral effect in the innate control of primary cutaneous HSV infection. B cells can also function as antigen-presenting cells for the stimulation of HSV-specific CD4+ T-cell responses. Consequently, CD4+ T cells and interferon-gamma responses were found to be significantly impaired in HSV-infected B-cell-deficient mice compared to that seen in control mice. No significant differences were found in natural-killer-cell- or HSV-specific CD8+ T-cell activity between control and B-cell-deficient mice. Our results imply a role for B cell in mediating innate and CD4+ T-cell-specific immunity in determining susceptibility to primary HSV infections.

Administration, Cutaneous↗

PubMed2000

Why do we lack an effective vaccine against herpes simplex virus infections?

This review discusses the possible causes for the lack of an effective antiherpes vaccine. Future prospects of vaccines based on the current knowledge of immune responses to herpes viruses are discussed. It is argued that vaccines capable of expanding CD8 T-cell memory responses should be the focus of future anti-herpes simplex virus research.

Animals↗

PubMed2000

Application of the intracellular gamma interferon assay to recalculate the potency of CD8(+) T-cell responses to herpes simplex virus.

Enumeration and characterization of herpes simplex virus (HSV)-specific CD8(+) T lymphocytes are tedious and indirect. We quantitated antigen-specific CD8(+) T cells during acute and secondary stages of HSV infection using intracellular gamma interferon production upon stimulation with virus or immunodominant peptide. Results show a substantial increase in the number of CD8(+) T cells which was otherwise underestimated with the conventional limiting dilution analysis.

Acute Disease↗