RESUMEN
A wide variety of the host immune elements play an influential role in the defence against cytomegalovirus (CMV) infection. However, the role of complement in the clearance of CMV infection is less well studied. Decay accelerating factor (DAF/CD55) is a membrane-bound complement regulatory protein that inhibits the formation and accelerates the decay of C3-convertase. Here we hypothesize that murine CMV (MCMV) utilizes DAF as an immunoevasive strategy through down-regulation of host adaptive responses against the virus. To test our hypothesis, DAF knock-out (DAF KO) C57BL/6 mice and wild-type (WT) littermates were infected with a sublethal dose of MCMV, and their immune responses were compared. WT mice lost 7·8% of their initial weight within the first 4 days after infection and quickly began to recover. This is in contrast to the DAF KO mice, that lost a total of 19·4% of their initial weight and did not start recovery until 6 days post-infection. Flow cytometric analysis of lung digests revealed that infected DAF KO mice had a significantly increased infiltration of inflammatory cells, the majority being CD8(+) T lymphocytes. Serum levels of tumour necrosis factor (TNF)-α and interferon (IFN)-γ were also increased markedly in the DAF KO mice compared to the infected WT mice. More interestingly, increased viral genome copies (DNA) in the splenocytes of DAF KO mice was accompanied with mRNA transcripts in the DAF KO mice, an indication of active viral replication. These data suggest an intriguing effect of reduced DAF expression on host responses following in vivo MCMV infection.
Asunto(s)
Antígenos CD55/inmunología , Infecciones por Herpesviridae/inmunología , Interacciones Huésped-Patógeno/inmunología , Muromegalovirus/inmunología , Animales , Antígenos CD55/genética , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/virología , ADN Viral/inmunología , Regulación Viral de la Expresión Génica/inmunología , Interferón gamma/sangre , Interferón gamma/inmunología , Enfermedades Pulmonares/inmunología , Enfermedades Pulmonares/virología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Muromegalovirus/genética , Bazo/inmunología , Bazo/virología , Factor de Necrosis Tumoral alfa/sangre , Factor de Necrosis Tumoral alfa/inmunologíaRESUMEN
Infection with cytomegalovirus (CMV) remains a significant cause of morbidity and mortality following allogeneic bone marrow transplantation (allo-BMT). The manifestations of CMV infection can range from neurological and haematological abnormalities to diminished graft survival and, in extreme cases, death. Many clinical studies have shown a direct correlation between cytomegalovirus infection and increased morbidity and mortality post allo-BMT, yet the exact mechanism is not well understood. Although driven primarily by T cell responses, the role of complement activation in acute and chronic graft-versus-host disease (GVHD) has also become more evident in recent years. The present studies were performed to examine the effects of murine cytomegalovirus (MCMV) infection on decay accelerating factor (DAF) and MCMVs role in exacerbating morbidity and mortality post-allo-BMT. Mice infected previously with a sublethal dose of MCMV (1 × 105 plaque-forming units) have reduced expression of DAF on lung tissues and lymphocytes following allo-BMT. More importantly, mortality rates post-allo-BMT in recipient DAF knock-out mice receiving wild-type bone marrow are increased, similar to wild-type MCMV-infected recipient mice. Similarly, DAF knock-out mice showed greater intracellular interferon (IFN)-γ production by lung CD8 T cells, and infection with MCMV further exacerbated both intracellular IFN-γ production by CD8 T cells and mortality rates post-allo-BMT. Together, these data support the hypothesis that MCMV infection augments morbidity and mortality post-allo-BMT by reducing surface DAF expression.
Asunto(s)
Trasplante de Médula Ósea/mortalidad , Antígenos CD55/metabolismo , Infecciones por Citomegalovirus/metabolismo , Animales , Peso Corporal/inmunología , Trasplante de Médula Ósea/inmunología , Trasplante de Médula Ósea/patología , Linfocitos T CD4-Positivos/patología , Antígenos CD55/genética , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Linfocitos T CD8-positivos/patología , Recuento de Células , Activación de Complemento/inmunología , Complemento C3a/metabolismo , Complemento C3d/metabolismo , Infecciones por Citomegalovirus/inmunología , Femenino , Proteínas Inmediatas-Precoces/inmunología , Molécula 1 de Adhesión Intercelular/metabolismo , Interferón gamma/metabolismo , Pulmón/metabolismo , Pulmón/patología , Pulmón/virología , Activación de Linfocitos/genética , Activación de Linfocitos/inmunología , Linfocitos/inmunología , Linfocitos/metabolismo , Linfocitos/patología , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Análisis de Supervivencia , Trasplante Homólogo , Molécula 1 de Adhesión Celular Vascular/metabolismoRESUMEN
The anti-inflammatory cytokine interleukin (IL)-10 plays an important role in the regulation of host-immune responses. Here we studied the role IL-10 plays in host responses to cytomegalovirus (CMV) infection. We demonstrate that manifestations of murine CMV (MCMV) disease are more severe in IL-10 knock-out mice, despite significantly reduced levels of viral replication. Cytokine analysis of serum revealed increased levels of interferon (IFN)-gamma, monocyte chemotactic protein 1 (MCP-1) and IL-6, all of which are potent stimulators of inflammatory responses. Depletion of IFN-gamma by monoclonal antibodies in IL-10 knock-out mice failed to improve the physical condition of the mice, while increasing viral replication. In contrast, serum levels of IL-6 in the knock-out animals were unaffected by IFN-gamma depletion and remained significantly elevated early in the course of infection. These data suggest that increased weight loss observed in IL-10 knock-out mice may be attributed to the uncontrolled production of proinflammatory cytokines, including IL-6.
Asunto(s)
Infecciones por Herpesviridae/inmunología , Interleucina-10/fisiología , Muromegalovirus/fisiología , Pérdida de Peso , Animales , Linfocitos T CD4-Positivos/inmunología , Quimiocina CCL2/análisis , Femenino , Citometría de Flujo , Infecciones por Herpesviridae/virología , Interferón gamma/análisis , Interleucina-10/genética , Interleucina-6/análisis , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , ARN Mensajero/análisis , Regulación hacia Arriba , Replicación ViralRESUMEN
The Forssman antigen has been proposed to be a target for the xenograft reaction in selected species combinations, including the rat and mouse, which are Forssman-negative and -positive species respectively. The mouse represents an important experimental model for a variety of immune-mediated disease processes, and the availability of a simple, inexpensive target antigen could provide an important tool for studying a selected portion of the immunologic basis for the rejection of xenografts. We have examined the potential that antibodies directed against mouse Forssman antigen could cause the hyperacute rejection of mouse heart xenografts in naive rat recipients. The Forssman antibodies tested included rat anti-mouse (R-anti-M) antiserum, R-anti-M antiserum depleted of anti-Forssman (anti-F) antibodies, rat anti-sheep red blood cell (SRBC) antiserum containing anti-F antibodies and a rat monoclonal anti-F IgM antibody. Our results demonstrate that the R-anti-M antiserum at day 4 post transplantation displayed significant titers (1:512-4096) of hemagglutinating antibodies for SRBC and mild to moderate levels of IgM that specifically binds to Forssman glycolipid (GalNAcalpha1-3GalNAcbeta1-3Galalpha1-4Galbeta1- 4Glcbeta1-1ceramide) as measured by an enzyme-linked immunosorbent assay (ELISA). Passive transfer of the R-anti-M serum to rats receiving mouse cardiac grafts immediately after transplantation caused hyperacute rejection of the xenografts. Sequential immunoabsorption of R-anti-M sera with SRBCs resulted in total removal of the anti-Forssman activity (as defined by negative hemagglutination titer and minimal binding to Forssman glycolipid in ELISA). The anti-F Ab-depleted R-anti-M antisera, however, retained the capacity to induce hyperacute rejection of the mouse hearts [n = 6, median survival time (MST) 13 min] when passively transferred to rat recipients. Anti-Forssman antibodies induced by immunization of LEW rats with SRBCs or a rat anti-Forssman monoclonal antibody, mAb M.1.22.25, exhibited substantial anti-Forssman activity (hemagglutinating titer 1:512-4096 and moderate-to-strong binding to Forssman glycolipid in ELISA respectively). These antibodies also failed, however, to trigger hyperacute rejection of mouse cardiac xenografts. In conclusion, our results suggest that the rat anti-Forssman antibodies, including those stimulated by mouse cardiac xenografts, do not appear to play a role in the immediate (hyperacute) rejection of mouse heart xenografts.
Asunto(s)
Antígeno de Forssman/inmunología , Rechazo de Injerto/inmunología , Trasplante de Corazón , Inmunología del Trasplante , Animales , Anticuerpos/inmunología , Ratones , Ratas , Trasplante HeterólogoRESUMEN
Lithium has been known for its ability to induce the production of hematopoietic cells following administration in vivo to minimize the toxic effects on hematopoiesis as a consequence of drug treatment. The drug hydroxyurea (HU), a ribonucleotide reductase inhibitor, has been used in the treatment of a variety of neoplastic and non-neoplastic diseases, such as cancer and sickle cell anaemia. Hydroxyurea has more recently been implicated for use in the treatment of acquired immunodeficiency syndrome (AIDS). However, its major limitations have been due to its toxicity. Hydroxyurea selectively inhibits DNA synthesis and due to its brief duration, the drug is only toxic to those cells which are selectively synthesizing DNA during the period of exposure. The most important of these toxicities, and which serves as a dose limiting factor in treatment, is the induction of bone marrow suppression. In this study we investigated the possible beneficial effects of administering lithium (LiCl) to murine leukemia virus (MuLV) infected and non-infected long term bone marrow cultures (LTBMC). These cultures were then treated with either 0.2 mM hydroxyurea, 1.0 mM LiCl, or a combination of both. Samples were collected from LTBMC supernatants at 1, 2, 3, 4, 5 and 6 weeks post-treatment. Culture supernatants were then monitored to observe their repopulation of hematopoietic progenitors. The results demonstrated the effects of lithium in restoring hydroxyurea suppressed numbers of myeloid (CFU-GM) progenitors to within a normal range and also in re-establishing erythroid (BFU-E) progenitors.
Asunto(s)
Células de la Médula Ósea/patología , Células de la Médula Ósea/virología , Células Madre Hematopoyéticas/patología , Hidroxiurea/farmacología , Cloruro de Litio/farmacología , Síndrome de Inmunodeficiencia Adquirida del Murino/patología , Inhibidores de la Síntesis del Ácido Nucleico/farmacología , Animales , Recuento de Células/efectos de los fármacos , División Celular/efectos de los fármacos , Células Cultivadas , Células Precursoras Eritroides/patología , Ratones , Ratones Endogámicos C57BL , Valores de ReferenciaRESUMEN
Lithium gamma linolenic acid (Li-GLA), was evaluated for its possible role as an antiviral agent. Li-GLA 15 micrograms ml-1 was administered to both normal and LP-BM5 MuLV retroviral infected murine bone marrow cultures. After 2 weeks of treatment, numbers of progenitors being produced by infected/treated cultures were reduced to some 10% that of normal cultures. In the remaining 4 weeks, numbers of CFU-GM and BFU-E hematopoietic progenitors returned within normal range. The efficacy of Li-GLA in relieving retroviral hematopoietic bone marrow suppression correlates to a reduction in interleukin-4 (IL-4) secretion, normally elevated in association with LP-BMP5 infection. These data indicate that this reduction in bone marrow suppression of LP-BMP5 infected cells may be due to a killing of infected cells by the Li-GLA, rather than stimulating hematopoiesis as with other lithium compounds. To conclude this may indicate the possible dual effect of administration of LiGLA to virally infected individuals in reducing viral titre and to lower the toxicities associated with long term drug therapy.
Asunto(s)
Antivirales/farmacología , Células Madre Hematopoyéticas/patología , Síndrome de Inmunodeficiencia Adquirida del Murino/patología , Ácido gammalinolénico/farmacología , Animales , Recuento de Células/efectos de los fármacos , Células Cultivadas , Células Precursoras Eritroides/efectos de los fármacos , Células Precursoras Eritroides/patología , Células Madre Hematopoyéticas/efectos de los fármacos , Células Madre Hematopoyéticas/metabolismo , Interleucina-4/metabolismo , Virus de la Leucemia Murina/fisiología , Megacariocitos/efectos de los fármacos , Megacariocitos/patología , Ratones , Ratones Endogámicos C57BL , Síndrome de Inmunodeficiencia Adquirida del Murino/metabolismo , Síndrome de Inmunodeficiencia Adquirida del Murino/virología , Factor de Crecimiento Transformador beta/metabolismo , Replicación ViralRESUMEN
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.