Circadian disruption and biomarkers of tumor progression in breast cancer patients awaiting surgery

Psychological distress, which can begin with cancer diagnosis and continue with treatment, is linked with circadian and endocrine disruption. In turn, circadian/endocrine factors are potent modulators of cancer progression. We hypothesized that circadian rest-activity rhythm disruption, distress, and diurnal cortisol rhythms would be associated with biomarkers of tumor progression in the peripheral blood of women awaiting breast cancer surgery. Breast cancer patients (n=43) provided actigraphic data on rest-activity rhythm, cancer-specific distress (IES, POMS), saliva samples for assessment of diurnal cortisol rhythm, cortisol awakening response (CAR), and diurnal mean. Ten potential markers of tumor progression were quantified in serum samples and grouped by exploratory factor analysis. Analyses yielded three factors, which appear to include biomarkers reflecting different aspects of tumor progression. Elevated factor scores indicate both high levels and strong clustering among serum signals. Factor 1 included VEGF, MMP-9, and TGF-β; suggesting tumor invasion/immunosuppression. Factor 2 included IL-1β, TNF-α, IL-6R, MCP-1; suggesting inflammation/chemotaxis. Factor 3 included IL-6, IL-12, IFN-γ; suggesting inflammation/TH1-type immunity. Hierarchical regressions adjusting age, stage and socioeconomic status examined associations of circadian, distress, and endocrine variables with these three factor scores. Patients with poor circadian coordination as measured by rest-activity rhythms had higher Factor 1 scores (R(2)=.160, p=.038). Patients with elevated CAR also had higher Factor 1 scores (R(2)=.293, p=.020). These relationships appeared to be driven largely by VEGF concentrations. Distress was not related to tumor-relevant biomarkers, and no other significant relationships emerged. Women with strong circadian activity rhythms showed less evidence of tumor promotion and/or progression as indicated by peripheral blood biomarkers. The study was not equipped to discern the cause of these associations. Circadian/endocrine aberrations may be a manifestation of systemic effects of aggressive tumors. Alternatively, these results raise the possibility that, among patients with active breast tumors, disruption of circadian activity rhythms and elevated CAR may facilitate tumor promotion and progression.

The impact of e-commerce on the role of IS professionals

Understanding the knowledge, skills and abilities of information systems professionals has been a longstanding goal of information systems research. An IS professional's ability to perform in his or her role is vital to the utilisation of information systems within an organisation. This research addresses the question: in what ways has the recent ascension of Internet-based electronic commerce altered the competency requirements of IS professionals? Semi-structured interviews were conducted with fifteen participants from a variety of public and private organizations, who are currently participating or had participated in e-commerce projects. The findings indicate that the implementation of e-commerce in organisations has introduced three main types of business changes: expectations, perceptions, and compliance. These three changes have in turn driven project changes and subsequent changes in the competency requirements and role of the IS professional. The implications of these changes for IS professionals and the organizations for which they work are discussed.

Reduction of cardiac volume in left-breast treatment fields by respiratory maneuvers: a CT study

PURPOSE

A previous study of healthy female volunteers suggested that deep inspiratory breath holding can reduce the cardiac volume in the treatment portals for left-breast cancer treatment. The reduction of irradiated cardiac volume may be important considering the reported late cardiac morbidity and mortality and the frequent coexistent use of potentially cardiotoxic chemotherapy in breast cancer patients. In the present study, we evaluated the heart volume in the fields and, thus, the true benefit of this respiratory maneuver in breast cancer patients undergoing CT simulation.

MATERIALS AND METHODS

Fifteen patients (median age, 53) were studied. For each patient, CT scans were performed both when the patient breathed normally (quiet respiration) and when the patient held her breath after a deep inspiration. Tangential fields were planned using the same medial, lateral, superior, and inferior borders on skin for the normal breathing and the breath-holding configurations. The cardiac and left-lung volumes within the tangential fields were calculated for both breathing configurations. Multiple scan series were performed for the breath-holding configuration to provide a more accurate delineation of the cardiac tissue and to study the reproducibility of the patient's position between different cycles of deep inspiration.

RESULTS

None of the patients had difficulty holding her breath for 20 s. The cardiac volume in the field was reduced (-86 +/- 24%; p < 0.001) when patients held their breath after a deep inspiration compared to when breathing normally. For 7 patients (47%), deep inspiration moved the heart completely out of the radiation fields. The expansion of the lung tissue due to deep inspiration also increased the absolute lung volume in the tangential fields (183 cm(3) vs 97 cm(3), p < 0.001). However, the fractional volume of the left lung in the field was essentially unchanged. For all but 1 patient, the maximum difference between the external body contours from different breath holding cycles was 5 mm and occurred at the lateral aspect of the breast. At the medial aspect, as indicated by the position of the midline marker, the variations were well within the currently accepted tolerance for patient positioning during tangential treatment.

CONCLUSIONS

Deep-inspiration breath holding substantially reduces cardiac volume in the tangential fields for left-sided breast cancer treatment. The variation between patient positions at different cycles of breath holding was found to be reasonably small. Therefore, it appears feasible to reduce cardiac radiation by treating patients with intratreatment minifractions lasting 10-15 s while patients hold their breath.

Influenza A virus hemagglutinin is a B cell-superstimulatory lectin

Influenza A viruses display T cell-independent polyclonal B cell-activating properties which are mediated by the B cell-superstimulatory envelope glycoprotein hemagglutinin (HA). In this report, the receptor-binding requirements for B cell activation by influenza viruses were expected. Neuraminidase treatment of resting mature B cells from BALB/c mice abrogated late (proliferation/immunoglobulin synthesis), early (up-regulation of cell surface markers, including CD25, B220, and B7-1) and very-early events (homotypic adhesion) in virus-responding B lymphocytes. Similarly, pretreatment of murine responder cells with different inhibitors of N-glycosylation (tunicamycin, deoxymannojirimycin) significantly suppressed subsequent B lymphocyte activation by HA, but not control responses to lipopolysaccharide or anti-mu. Assays with chimeric HA transfectants, expressing the loop region of epitope B (amino acids 155-160) of the globular head of H2 (high B cell-stimulatory subtype) or H3 (medium-stimulatory subtype) on the protein backbone of a low-stimulatory subtype (H1) failed to alter the B cell-stimulatory activity of the virus, suggesting that the hypervariable loop region is not crucial in determining the B cell-activating properties of the protein. Collectively, our results imply that the B cell-superstimulatory function of influenza virus HA is not mediated by a direct protein/protein interaction, but via binding of HA to terminal sialic acid residues on cell surface receptor glycoproteins. These findings identify the influenza virus HA glycoprotein as the first viral lectin with lymphocyte-activating properties.

Superstimulatory influenza virus and highly organized BCR-ligands act synergistically on B cell activation

The influenza virus glycoprotein hemagglutinin (HA) behaves as a superstimulatory protein for B lymphocytes from various species. Polyclonal B cell stimulation mediated by HA can be blocked by soluble anti-Ig antibodies. We here report that, if presented in a highly organized form, i.e., as anti-Ig mAb coupled to dextran (anti-Ig-Dex), conventional BCR-ligands and influenza viruses act synergistically on murine B cell activation. Proliferative responses of both spellen-derived and peritoneal B cells mediated by suboptimal amounts of HA were significantly augmented by costimulation with anti-Ig-Dex, and vice versa. Similarly, anti-Ig-Dex, which on its own cannot induce Ig production in the absence of added cytokines, significantly enhanced Ig synthesis in response to superstimulatory HA. By contrast, poorly organized BCR-ligands (i.e. the same anti-Ig mAb in a soluble form) had either no, or a strong inhibitory effect on virus-triggered lymphocyte activation. Assays with various second messenger-antagonists, however, revealed clear differences in the signaling pathway employed by anti-Ig-Dex and HA, suggesting that the functional synergy between the two multimeric agents is mediated by engagement of distinct transducing elements. Taken together, these results indicate that the superstimulatory function of influenza virus HA represents a molecular strategy to mimick B cell activation by conventional, highly organized particulate-antigens.

B cell superstimulatory influenza virus activates peritoneal B cells

We evaluated the potential of B cell "superstimulatory" influenza viruses to activate peritoneal B cells (PBC) from BALB/c mice containing both CD5+ and CD5- "sister" cells. Like conventional B cells, PBCs responded to influenza viruses in a hemagglutinin glycoprotein (HA) subtype-specific manner with proliferation and vigorous Ig synthesis. However, a number of HA subtypes that are highly stimulatory for conventional B cells failed to induce significant responses of PBC. Isotype-determination revealed a high predominance of IgM and only very low production of IgA and IgG. HA-activated CD5+ B cells showed a hyperexpression of various activation markers, including MHC class II, intercellular adhesion molecule 1 (CD54), and B7-1 molecules. In contrast to conventional B cells, where activation by HA is antagonized by phorbol esters (PMA), HA and PMA acted synergistically on PBC, suggesting differential activation requirements of B-2 cells vs PBC in response to HA. Like HA stimulation of B-2 cells, virus-triggered proliferation of PBC was abrogated by a simultaneous treatment with F(ab')2 fragments of anti-Ig Ab and exhibited synergistic effects with LPS stimulation. HA-mediated proliferative responses of PBC, but not of B-2 cells, were positively controlled by various cytokines, including IL-4 and IL-10, and to a lesser extent by IL-6. In conclusion, our data present the first example of a stimulation of peritoneal B cells by a polyclonal-activating virus, findings that call for considering infections with polyclonal B cell-stimulatory viruses as a means of expanding the pool of potentially autoreactive CD5+ B cells.

B cell superstimulatory influenza virus activates peritoneal B cells

We evaluated the potential of B cell "superstimulatory" influenza viruses to activate peritoneal B cells (PBC) from BALB/c mice containing both CD5+ and CD5- "sister" cells. Like conventional B cells, PBCs responded to influenza viruses in a hemagglutinin glycoprotein (HA) subtype-specific manner with proliferation and vigorous Ig synthesis. However, a number of HA subtypes that are highly stimulatory for conventional B cells failed to induce significant responses of PBC. Isotype-determination revealed a high predominance of IgM and only very low production of IgA and IgG. HA-activated CD5+ B cells showed a hyperexpression of various activation markers, including MHC class II, intercellular adhesion molecule 1 (CD54), and B7-1 molecules. In contrast to conventional B cells, where activation by HA is antagonized by phorbol esters (PMA), HA and PMA acted synergistically on PBC, suggesting differential activation requirements of B-2 cells vs PBC in response to HA. Like HA stimulation of B-2 cells, virus-triggered proliferation of PBC was abrogated by a simultaneous treatment with F(ab')2 fragments of anti-Ig Ab and exhibited synergistic effects with LPS stimulation. HA-mediated proliferative responses of PBC, but not of B-2 cells, were positively controlled by various cytokines, including IL-4 and IL-10, and to a lesser extent by IL-6. In conclusion, our data present the first example of a stimulation of peritoneal B cells by a polyclonal-activating virus, findings that call for considering infections with polyclonal B cell-stimulatory viruses as a means of expanding the pool of potentially autoreactive CD5+ B cells.

Superantigens induce primary T cell responses to soluble autoantigens by a non-V beta-specific mechanism of bystander activation

Superantigens have been suggested to act as powerful TCR V beta-specific inducers of T cell reactivity in autoimmune diseases. We have investigated the capacity of staphylococcal enterotoxins (SE) to prime autoreactive T cell responses in naive animals in the Lewis rat model of experimental autoimmune encephalomyelitis (EAE), where myelin basic protein (MBP)-specific CD4+ effector T cells express almost exclusively V beta 8.2 TCR elements. By taking advantage of the reactivity of V beta 8.2+ MBP-specific T cells to SEE but not to other SEs in vitro, we estimated the potential of different SEs (SEA, SEB, and SEE) to induce a primary T cell response to soluble MBP in vivo. Upon immunization of naive rats with soluble MBP alone or MBP and SEB (which is only a very weak superantigen for rat T cells), no MBP-responses could be retrieved. Similarly, when coimmunizing naive rats with MBP and V beta 8.2-activating SEE, no autoreactivity was inducible. By contrast, coimmunization of animals with soluble MBP and the superantigen SEA that is strongly activating various T cell subpopulations in Lewis rats but not V beta 8.2+ (i.e., potentially MBP reactive) T cells led to a significant primary MBP-specific T cell autoreactivity. These SEA-induced MBP-reactive T cells expressed V beta 8.2 TCRs at levels similar to those seen in autoreactive T cells conventionally induced by immunization with MBP administered in complete Freund's adjuvant (CFA) and could induce disease in a transfer model of EAE. Thus, our results are consistent with the notion that superantigens are able to induce primary T cell responses to soluble autoantigens by a non-V beta specific mechanism of bystander priming.

B cell superstimulatory influenza virus (H2-subtype) induces B cell proliferation by a PKC-activating, Ca(2+)-independent mechanism

The influenza virus hemagglutinin glycoprotein (HA) induces a vigorous B cell proliferation and Ig-synthesis by an unknown activation mechanism, which is susceptible to the inhibitory effects of anti-Ig and anti-class II mAbs. To gain further insight into the activation mode of this T cell-independent, B cell "superstimulatory" virus, we analyzed the sensitivity of H2-subtype virus-mediated B cell activation to the inhibitory effects of various signal transduction-blocking agents and compared it to the well characterized anti-mu-mediated and the LPS-employed pathway. Cyclic-AMP agonists (cAMP-analogues, pentoxifylline, cholera toxin, and forskolin) blocked HA-mediated activation of B cells only at concentrations at least 50-fold higher than required for blocking of anti-mu-induced activation. However, HA-treatment failed to induce an increase in intracellular cAMP levels in responding B cells. The B cell response to HA was highly resistant to calcineurin-inhibitory cyclosporin-A treatment and did not result in a measurable Ca2+ influx. Similarly, HA failed to induce an increase in tyrosine phosphorylations, including phosphorylation of phospholipase C gamma 2. HA-activated B cells showed an increase in membrane-associated protein kinase C activity, and depletion of protein kinase C by pretreatment of B cells with phorbol esters inhibited a subsequent activation by HA. Collectively, our results provide a new example of B cell stimulation by multivalent type-2 Ags, which seems to be mediated by a phosphatidylinositol- and Ca(2+)-independent signaling pathway.

B cell superstimulatory influenza virus (H2-subtype) induces B cell proliferation by a PKC-activating, Ca(2+)-independent mechanism

The influenza virus hemagglutinin glycoprotein (HA) induces a vigorous B cell proliferation and Ig-synthesis by an unknown activation mechanism, which is susceptible to the inhibitory effects of anti-Ig and anti-class II mAbs. To gain further insight into the activation mode of this T cell-independent, B cell "superstimulatory" virus, we analyzed the sensitivity of H2-subtype virus-mediated B cell activation to the inhibitory effects of various signal transduction-blocking agents and compared it to the well characterized anti-mu-mediated and the LPS-employed pathway. Cyclic-AMP agonists (cAMP-analogues, pentoxifylline, cholera toxin, and forskolin) blocked HA-mediated activation of B cells only at concentrations at least 50-fold higher than required for blocking of anti-mu-induced activation. However, HA-treatment failed to induce an increase in intracellular cAMP levels in responding B cells. The B cell response to HA was highly resistant to calcineurin-inhibitory cyclosporin-A treatment and did not result in a measurable Ca2+ influx. Similarly, HA failed to induce an increase in tyrosine phosphorylations, including phosphorylation of phospholipase C gamma 2. HA-activated B cells showed an increase in membrane-associated protein kinase C activity, and depletion of protein kinase C by pretreatment of B cells with phorbol esters inhibited a subsequent activation by HA. Collectively, our results provide a new example of B cell stimulation by multivalent type-2 Ags, which seems to be mediated by a phosphatidylinositol- and Ca(2+)-independent signaling pathway.

Microglial cells qualify as the stimulators of unprimed CD4+ and CD8+ T lymphocytes in the central nervous system

The potential of central nervous system (CNS)-derived cells for initiating T cell responses is not known. Using the capacity of unprimed T cells to respond to allogeneic determinants on antigen-presenting cells (APC), we assessed the ability of microglial cells to act as stimulators of primary T cell responses in vitro. For this purpose, microglial cells were activated with lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), or by phagocytosis of progenitor oligodendrocytes and subsequently tested for their ability to induce a proliferative response of naive, resting T cells. Activated microglial cells induced a significant proliferation of virgin, alloreactive CD4+ and CD8+ T lymphocytes, with a more substantial response of highly purified CD4+ than of CD8-expressing T cells. Phagocytosis activation was the most efficient stimulus to induce this APC competence on microglial cells. By contrast, IFN-gamma-pretreated, MHC-expressing astrocytes were unable to induce similar responses of alloreactive CD4+ or CD8+ T cells under the same experimental conditions. Collectively, our data suggest the role of activated microglia as the fully immunocompetent accessory cell population of the CNS.

Macrophage-inactivating IL-13 suppresses experimental autoimmune encephalomyelitis in rats

Experimental autoimmune encephalomyelitis (EAE) is initiated by myelin basic protein (MBP)-specific CD4+ T cells of the Th1 phenotype that subsequently trigger the invasion of monocytes/macrophages into the brain. In this study, we evaluated the potential of human recombinant (hr) IL-13 to exert a protective effect on the development of EAE in Lewis rats. hrIL-13 is found to be a potent in vitro modulator of various rat macrophage functions, including an inhibition of the production of the proinflammatory cytokines IL-1 beta and TNF, and a simultaneous enhancement of MHC class II and CD4 receptor expression. Furthermore, hrIL-13 displayed a slight, but highly reproducible, inhibitory effect on the in vitro proliferative responses of encephalitogenic MBP-specific T cells stimulated in the presence of thymic APCs. Upon in vivo application of hrIL-13-secreting vector cells into MBP-immunized animals, the cytokine was capable of markedly suppressing the development of EAE, as assessed by a reduction of the mean duration, severity, and incidence of disease. This suppression of disease coincided with an only minimal reduction of MBP-directed T cell autoreactivity and no alteration in MBP-specific autoantibody production. We infer from these results that a strictly Th1-initiated immune disease can be attenuated efficiently by the administration of a cytokine that primarily targets cells of the macrophage/monocyte lineage and seems to exert no undesirable general suppression on either T cell or B cell immunoreactivity in vivo.

Macrophage-inactivating IL-13 suppresses experimental autoimmune encephalomyelitis in rats

Experimental autoimmune encephalomyelitis (EAE) is initiated by myelin basic protein (MBP)-specific CD4+ T cells of the Th1 phenotype that subsequently trigger the invasion of monocytes/macrophages into the brain. In this study, we evaluated the potential of human recombinant (hr) IL-13 to exert a protective effect on the development of EAE in Lewis rats. hrIL-13 is found to be a potent in vitro modulator of various rat macrophage functions, including an inhibition of the production of the proinflammatory cytokines IL-1 beta and TNF, and a simultaneous enhancement of MHC class II and CD4 receptor expression. Furthermore, hrIL-13 displayed a slight, but highly reproducible, inhibitory effect on the in vitro proliferative responses of encephalitogenic MBP-specific T cells stimulated in the presence of thymic APCs. Upon in vivo application of hrIL-13-secreting vector cells into MBP-immunized animals, the cytokine was capable of markedly suppressing the development of EAE, as assessed by a reduction of the mean duration, severity, and incidence of disease. This suppression of disease coincided with an only minimal reduction of MBP-directed T cell autoreactivity and no alteration in MBP-specific autoantibody production. We infer from these results that a strictly Th1-initiated immune disease can be attenuated efficiently by the administration of a cytokine that primarily targets cells of the macrophage/monocyte lineage and seems to exert no undesirable general suppression on either T cell or B cell immunoreactivity in vivo.

Influenza virus hemagglutinin induces differentiation of mature resting B cells and growth arrest of immature WEHI-231 lymphoma cells

We have investigated the functional requirements for the B cell "mitogenicity" of the influenza virus hemagglutinin (HA). Murine B cell proliferative responses were inducible by either infectious or inactivated virus, and by infected, paraformaldehyde-fixed cells. Viruses of the 12 different HA-subtypes displayed marked differences in their activation potential, classifying them as high (H2, H4, H6, H12), medium (H3, H5, H8, H9), or low (H1, H7, H10, H11) B cell activators. HA-mediated proliferation of resting B cells induced a vigorous Ig synthesis, with a predominance of IgG2b, IgG3, and IgM production. In this activation mode the B cell receptor (BCR) complex seems to be involved because 1) virus-triggered B cell proliferation was blocked by anti-Ig Abs, 2) B cell responses could be competitively inhibited by unfractionated high dose Igs, and 3) addition of BCR-modulating anti-CD45 mAb abrogated subsequent stimulation by HA. Furthermore, 4) influenza viruses were able to induce a growth arrest in the anti-mu sensitive B cell line WEHI-231. Most interestingly, the "tolerogenic" capacity correlated with the B cell stimulatory subtype of the virus, because highly stimulatory HA-subtypes were highly "tolerogenic" whereas low stimulatory subtypes were only marginally effective. Collectively, these observations raise the hypothesis that influenza viruses can cause polyclonal proliferation/differentiation of mature B cells and inactivation/tolerance induction in immature B cells by a mechanism that seems to mimic certain aspects of the physiologic BCR complex-mediated B cell activation.

Interleukin-10 prevents experimental allergic encephalomyelitis in rats

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease mediated by myelin protein-specific CD4+ T lymphocytes of the T(h)1-like phenotype. In rats, the disease is characterized by a monophasic clinical manifestation, followed by a subsequent spontaneous remission and the establishment of life-long resistance to reinduction of disease. Recent data indicate that intracerebral cytokine production, in particular synthesis of interleukin(IL)-10, is selectively up-regulated during the recovery phase of disease. This led us to assess the effects of IL-10 on different rat lymphoid cell functions in vitro and to consider the possibility of an IL-10-mediated treatment to prevent the induction of central nervous system (CNS) autoimmune disease in vivo. Human recombinant IL-10 suppressed interferon-gamma induced major histocompatibility complex class II up-regulation in rat peritoneal macrophages, exhibited pleiotropic effects on thymocytes and totally abrogated tumor necrosis factor production of encephalitogenic T lymphocytes in vitro, without simultaneously affecting proliferative responses of the cells. Upon systemic administration during the initiation phase of disease, IL-10 was effective in markedly suppressing the subsequent induction of EAE in Lewis rats. This suppression of clinical disease coincided with a significant and specific elevation of myelin basic protein-specific autoantibody production, a sustained T cell proliferative response to myelin basic protein and a diminution of CNS infiltrations and thymic involutions in diseased animals. These data implicate IL-10 as a possible candidate for treatment of T(h)1-mediated CNS (auto-) immune diseases.

Influenza virus hemagglutinin induces differentiation of mature resting B cells and growth arrest of immature WEHI-231 lymphoma cells

We have investigated the functional requirements for the B cell "mitogenicity" of the influenza virus hemagglutinin (HA). Murine B cell proliferative responses were inducible by either infectious or inactivated virus, and by infected, paraformaldehyde-fixed cells. Viruses of the 12 different HA-subtypes displayed marked differences in their activation potential, classifying them as high (H2, H4, H6, H12), medium (H3, H5, H8, H9), or low (H1, H7, H10, H11) B cell activators. HA-mediated proliferation of resting B cells induced a vigorous Ig synthesis, with a predominance of IgG2b, IgG3, and IgM production. In this activation mode the B cell receptor (BCR) complex seems to be involved because 1) virus-triggered B cell proliferation was blocked by anti-Ig Abs, 2) B cell responses could be competitively inhibited by unfractionated high dose Igs, and 3) addition of BCR-modulating anti-CD45 mAb abrogated subsequent stimulation by HA. Furthermore, 4) influenza viruses were able to induce a growth arrest in the anti-mu sensitive B cell line WEHI-231. Most interestingly, the "tolerogenic" capacity correlated with the B cell stimulatory subtype of the virus, because highly stimulatory HA-subtypes were highly "tolerogenic" whereas low stimulatory subtypes were only marginally effective. Collectively, these observations raise the hypothesis that influenza viruses can cause polyclonal proliferation/differentiation of mature B cells and inactivation/tolerance induction in immature B cells by a mechanism that seems to mimic certain aspects of the physiologic BCR complex-mediated B cell activation.

Autoimmunity caused by host cell protein-containing viruses

Autoreactive T cells specific for myelin basic protein (MBP), a major component of central nervous system (CNS) protein, are frequently found in blood and cerebrospinal fluid of patients with postinfectious encephalomyelitis. This autoimmune syndrome is a CNS complication after infections with a number of different enveloped viruses, e.g. mumps, measles, rubella, influenza and varicella. However, the pathophysiological mechanism leading to this breaking of natural self tolerance in the course of viral infection remains an enigma. A long-lasting hypothesis has suggested that incorporation of cellular (self) proteins into the envelope of budding viruses might be a possible mechanism leading to autosensitization. In a model study we demonstrate here that vesicular stomatitis virus (VSV), grown in myelin protein-expressing cell cultures, is highly efficient in triggering T cell responses to MBP in vitro and can prime autoreactive T cell immune responses in vivo. On the basis of these findings, we suggest that incorporation of CNS membrane components into the viral envelope and subsequent priming of self-reactive immune responses might be the common pathogenic mechanism underlying the postinfectious encephalomyelitis syndrome.

T cell memory specific for self and non-self antigens in rats persistently infected with Borna disease virus

We have studied CD4+ Th1 T cell responses in Borna disease (BD), a virus-mediated immune disease of the central nervous system (CNS), and demonstrate the priming of virus-specific as well as autoreactive T cells specific for myelin antigens in the course of viral infection. The fate of these in vivo generated T cells was subsequently assessed by in vitro proliferation assays with lymphocytes from different lymphoid organs of diseased animals over a long period of time. Virus-specific T cell responses continuously decreased during the establishment of persistent infection and could no longer be detected after 5-6 months post infectionem, when inflammatory reactions in the brain had ceased. By contrast, autoantigen-specific T cells kept their ability to mount characteristic secondary responses--although at an overall rather low level--over long periods of time; these autoreactive T cells homed to a specific lymphoid organ, the perithymic lymph node. Our study thus describes for the first time a complete decline of virus-specific T cell memory in a persistent viral infection, and raises the question how long-lasting T cell autoreactivity is controlled.

Phosphodiesterase inhibitor pentoxifylline, a selective suppressor of T helper type 1- but not type 2-associated lymphokine production, prevents induction of experimental autoimmune encephalomyelitis in Lewis rats

The phosphodiesterase inhibitor pentoxifylline (POX), which is known to have pharmacological effects in animal models of multiorgan failure and endotoxin-mediated shock, was tested for its immunosuppressive potential on T lymphocyte activation in vitro and in vivo. POX was found to have a profound inhibitory effect on both mitogen- and antigen-induced proliferation of CD4+ T cells in vitro. This inhibitory activity of the drug could be reproduced by treating T lymphocytes with cAMP analogues during stimulation. Responses of repeatedly in vitro stimulated cells were much more strongly inhibited by the drug and by cAMP analogues than responses of fresh resting lymphocytes. Furthermore, POX could drastically down-regulate tumor necrosis factor regulate production and to a lesser extent interleukin (IL)-2 secretion in activated T cells, but an excess of exogenous IL-2 did not override the antiproliferative effect of the drug. In contrast, the same doses of POX had no inhibitory effect on spontaneous or induced IL-4 and IL-6 production by short-term cultured T lymphocytes, indicating a selective sparing of T helper type 2 (Th2)-associated lymphokine functions by the drug. To test a potential use of POX as an antiinflammatory agent in T cell-mediated autoimmune disease, the influence of POX on myelin basic protein (MBP)-induced experimental autoimmune encephalomyelitis (EAE) was assessed. The onset of EAE in Lewis rats could almost completely be abrogated by oral administration of POX during the induction phase of disease. Lack of clinical symptoms in POX-treated animals coincided with a marked suppression of MBP-specific T cell reactivity in vitro, without any evidence for a generalized impairment of T cell activity. Collectively, our data suggest the potential use of xanthine derivatives of the POX type as a supporting antiinflammatory therapeutic agent in Th1 CD4+ T cell-mediated autoimmune diseases in animal models and possibly in man.

Interleukin-6 production in "normal" and HTLV-1 tax-expressing brain-specific endothelial cells

Abnormal cytokine production can contribute in many instances to the development of pathology. Our study focuses on the regulation of interleukin (IL)-6 production in vitro in brain-specific endothelial cells (BEC) under physiological conditions and in a model of human T leukemia virus-1 (HTLV-1) infection. IL-6 production was strongly up-regulated in a dose-dependent mode upon exposure to recombinant IL-1 beta, although nearly not detectable in unstimulated BEC. This induction of IL-6 production could be achieved by reagents known to increase intracellular levels of cAMP, such as forskolin, prostaglandin E or pentoxifylline. Furthermore, transcription and production of IL-6 was inducible by addition of dibutyryl cAMP, but not by addition of calcium ionophores or diacylglycerol. To assess a potential role of HTLV-1-infected BEC in the pathogenesis of tropical spastic paraparesis (TSP), the HTLV-1 tax gene was expressed in BEC. Tax gene-expressing BEC produced constitutively very high amounts of IL-6, which were not longer hyperinducible by IL-1 beta or cAMP derivatives. Our results indicate that HTLV-1 tax induces hyperproduction of IL-6 in brain-specific endothelial cells directly by an intracellular mechanism which subsequently renders IL-6 production independent of exogenous stimuli or activators of (cAMP-dependent) second messenger levels. On the basis of these findings we suggest that tax-mediated hyperactivation of IL-6 production in BEC contributes to elevated IL-6 levels found in serum and cerebrospinal fluid of patients with TSP and might have a significance in the immune pathogenesis of the disease.

Microglia present myelin antigens to T cells after phagocytosis of oligodendrocytes

Cells that are capable of initiating immune reactions in the central nervous system (CNS) seem to be microglia, since they are the predominant CNS cell type expressing major histocompatibility complex (MHC) class II molecules. However, the capacity of microglia to induce myelin antigen-specific T lymphocyte activation is not yet well defined. With a coculture system allowing phagocytosis by microglia of progenitor or mature oligodendrocytes (synthesizing myelin basic protein, MBP), we show the ability of phagocytosis-activated microglia to express MHC class II antigen and to strongly induce T cell proliferation. The T cell proliferation was either mitogen mediated or antigen specific (MBP). Activation of microglia by phagocytosis may represent a major step in initializing immune responses in the CNS.

Cells of cerebrospinal fluid of multiple sclerosis patients secrete antibodies to myelin basic protein in vitro

To characterize the role of B lymphocytes in the pathogenesis of Multiple Sclerosis (MS), we have isolated mononuclear cells from cerebrospinal fluid (CSF) and stimulated them with a polyclonal B-cell mitogen (pokeweed mitogen). This study has been done with MS patients selected for the occurrence of an acute attack in the course of the disease and with patients hospitalized for other neurological diseases. Five of the 11 MS patients had B lymphocytes producing in vitro antibodies (Abs) directed against purified human myelin basic protein (hMBP), as revealed by Western blot analysis. None of the 20 patients with other neurological diseases showed such a reactivity. The produced Abs recognized only 1 or 2 hMBP peptides without dominance for a certain peptide. This result emphasizes the presence of B cells producing Abs against MBP in CSF of MS patients and shows the interest of studying mononuclear cells of CSF as a good marker of the pathogenesis.

Role of the humoral immune response in resistance to Theiler's virus infection

Theiler's virus, a murine picornavirus, persists in the central nervous system of susceptible strains of mice, causing chronic inflammation and demyelination in the white matter of the spinal cord. Resistant strains, however, clear the virus and do not develop late disease. In this study, we compared the characteristics of T and B lymphocytes in C57BL/6 (resistant) and SJL/J (susceptible) mice 1 week after intracerebral infection. We detected a marked increase of the number of immunoglobulin M (IgM)-secreting cells in the spleens of C57BL/6 detected a marked increase of the number of immunoglobulin M (IgM)-secreting cells in the spleens of C57BL/6 mice (but not in those of SJL/J mice), which correlated with higher levels of serum IgM antiviral antibodies. The role of the humoral response in virus clearance and resistance was demonstrated by a marked decrease in the number of infected spinal cord cells in SJL/J mice after passive transfer of serum from infected C57BL/6 donors. The B-cell response was found to be partly T cell independent. These results suggest an important role of the early humoral immune response in resistance to Theiler's virus-induced disease.

Effector T lymphocytes present in demyelinating lesions induced by Theiler's virus

Theiler's virus causes chronic primary demyelination associated with viral persistence in SJL/J mice. We have investigated the effector functions of T lymphocytes isolated from inflammatory brain lesions to detect a local immune dysfunction associated with viral persistence. In vitro, CD4+ T cells induced B-lymphocyte proliferation and antibody secretion; CD8+ T cells had cytolytic activity. Therefore, Theiler's virus persistence does not include local immune unresponsiveness.

Characterization of B lymphocytes present in the demyelinating lesions induced by Theiler's virus

Theiler's virus, a murine picornavirus, persists in the central nervous system of SJL/J mice and causes inflammation and demyelination in the white matter of spinal cord. We isolated inflammatory cells from the central nervous system of infected animals and studied their functions in vitro. Flow microfluorimetry analysis showed the presence of all major lymphocyte subsets, namely CD4+ and CD8+ T cells as well as B lymphocytes. B lymphocytes were activated in vitro and the antigenic specificity of secreted Ig was determined by immunoblotting. Secreted Ig reacted strongly with viral capsid proteins VP1 and VP2 and had neutralizing activity. They reacted also with two nonviral white matter components which were present only in infected animals. Therefore, it is likely that Igs secreted at the site of infection play a role in limiting virus spread. It is also possible that virus induced autoreactive antibodies participate in demyelination.

Characterization of B lymphocytes present in the demyelinating lesions induced by Theiler's virus

Theiler's virus, a murine picornavirus, persists in the central nervous system of SJL/J mice and causes inflammation and demyelination in the white matter of spinal cord. We isolated inflammatory cells from the central nervous system of infected animals and studied their functions in vitro. Flow microfluorimetry analysis showed the presence of all major lymphocyte subsets, namely CD4+ and CD8+ T cells as well as B lymphocytes. B lymphocytes were activated in vitro and the antigenic specificity of secreted Ig was determined by immunoblotting. Secreted Ig reacted strongly with viral capsid proteins VP1 and VP2 and had neutralizing activity. They reacted also with two nonviral white matter components which were present only in infected animals. Therefore, it is likely that Igs secreted at the site of infection play a role in limiting virus spread. It is also possible that virus induced autoreactive antibodies participate in demyelination.

Minus-strand RNA synthesis in the spinal cords of mice persistently infected with Theiler's virus

Theiler's virus, a murine picornavirus, causes a chronic neurological disease characterized by primary demyelination in SJL/J mice. The lesions are very reminiscent of those of multiple sclerosis. Theiler's virus persists in oligodendrocytes and to a lesser extent in astrocytes and macrophages throughout the disease. Viral RNA and capsid protein syntheses are minimal in these cells. This restriction could play a central role in the mechanism of virus persistence. By quantitating plus- and minus-strand RNAs in infected central nervous system cells, we showed that RNA replication was blocked at the level of minus-strand RNA synthesis.

Quantitation, with a new assay, of Theiler's virus capsid protein in the central nervous system of mice

We developed a quantitative assay for antigens at the single-cell level. Tissue sections were reacted with a primary antibody, a biotinylated secondary antibody, or 35S-streptavidin. Binding of streptavidin to cells was quantitated by microscopic autoradiography. We showed that the number of autoradiographic grains was proportional to the amount of antigen per cell. With this assay, we studied the synthesis of Theiler's virus capsid proteins VP1, VP2, and VP3 in permissive BHK cells grown in vitro and in mouse central nervous system (CNS) cells during a persistent infection. We found that synthesis of the three capsid proteins was restricted in mouse CNS cells. Restricted virus replication could play a major role in the persistence of Theiler's virus in mouse CNS cells.

Quantitative in situ hybridization using initial velocity measurements

In situ hybridization can be used to quantitate viral RNA at the single cell level by measuring levels of hybridization after saturation hybridization with an excess of cDNA probe has been achieved (1,2). In this paper we describe an alternative approach which consists in measuring the initial hybridization rate using a low concentration of cDNA probe and a short hybridization time. Under these conditions, we obtained a linear relationship between the number of autoradiographic grains and the number of viral genomes per cell in the range of 600 to 60,000 copies per cell of a 7-kb RNA genome. This approach allows an accurate measurement of copy number in a range for which saturation in situ hybridization is very difficult to achieve.

Detection of picornavirus sequences in nervous tissue of amyotrophic lateral sclerosis and control patients

We used in situ hybridization to look for picornavirus ribonucleic acid (RNA) sequences in frozen sections of central nervous system (CNS) tissue of amyotrophic lateral sclerosis (ALS) and control patients. Using reconstruction experiments, we concluded that 30 copies of viral RNA per cell could be detected with the assay. RNA which hybridized to DNAs complementary (cDNAs) to both poliovirus and Theiler's virus was found at several levels in the CNS of 2 patients, 1 ALS patient, and 1 control. In transverse sections of the spinal cord, these sequences predominated in cells of the anterior horns. We assessed the specificity of hybridization by several criteria: no hybridization was observed with heterologous visna virus cDNA probes; hybridization was abolished by pretreatment of the sections with ribonuclease; chemography artifacts were ruled out; and the results were reproduced in three independent experiments. We concluded that RNA molecules, possibly belonging to a picornavirus having sequences in common with poliovirus and Theiler's virus, were present in the CNS of these 2 patients. On the other hand, 14 cases of classic ALS, 2 cases of Guamanian parkinsonian dementia, and 5 controls had negative results. However, the presence of picornavirus sequences in our series could be underestimated because in many cases autolysis times were 10 hours or longer.

Theiler's virus RNA and protein synthesis in the central nervous system of demyelinating mice

We studied Theiler's virus RNA and capsid protein synthesis in sections of mouse spinal cord using in situ hybridization coupled to immunoperoxidase. We found that the majority of infected cells contain 100 to 500 viral genomes and no detectable capsid antigens. Similarly, baby hamster kidney (BHK) cells, which are permissive to Theiler's virus, do not synthesize capsid if they contain less than 1000 viral genomes. Our results demonstrate that virus multiplication is restricted in vivo at the level of RNA replication. They suggest that RNA restriction is sufficient to explain the lack of capsid antigen synthesis.

Simultaneous in situ detection of viral RNA and antigens

We have combined in situ hybridization and immunocytochemistry to detect RNA and proteins in the same cell. We envision a wide range of applications for this method, and, as one example, we show that viral genomes and capsid antigens can be detected simultaneously in paraffin sections of the central nervous system of mice infected with Theiler's virus, the causative agent of a slow demyelinating disease.