RESUMEN
Cancer immunotherapy with dendritic cell (DC)-based vaccines has been used to treat various malignancies for more than two decades, however generally showed a limited clinical success. Among various factors responsible for their modest clinical activity is the lack of universally applied, standardized protocols for the generation of clinical-grade DC vaccines, capable of inducing effective anti-tumor immune responses. We investigated Bacterial Ghosts (BGs) - empty envelopes of Gram-negative bacteria - as a tool for optimized production of DC vaccines. BGs possess various intact cell surface structures, exhibiting strong adjuvant properties required for the induction of DC maturation, whereas their empty internal space can be easily filled with a source tumor antigens, e.g. tumor lysate. Hence BGs emerge as an excellent platform for both the induction of immunogenic DC maturation and loading with tumor antigens in a single-step procedure. We compared the phenotype, cytokine secretion profile, functional activity and ability to induce immunogenic T-cell responses in vitro of human monocyte-derived DCs generated using BG platform and DCs matured with widely used lipopolysaccharide (LPS) plus interferon-γ cocktail and loaded with tumor lysate. Both approaches induced DC maturation, however BG-based protocol was superior to LPS-based protocol in terms of the ability to induce DCs with a lower tolerogenic potential, resulting in a more robust CD8+ T cell activation and their functional activity as well as significantly lower induction of regulatory T cells. These superior parameters are attributed, at least in part, to the ability of BG-matured DCs to resist potential immunosuppressive and pro-tolerogenic activity of various tumor cell lysates, including melanoma, renal carcinoma and glioblastoma.
Asunto(s)
Adyuvantes Inmunológicos , Antígenos de Neoplasias/inmunología , Vacunas Bacterianas/inmunología , Vacunas contra el Cáncer/inmunología , Células Dendríticas/inmunología , Neoplasias/terapia , Linfocitos T CD8-positivos/inmunología , Vacunas contra el Cáncer/aislamiento & purificación , Diferenciación Celular , Citocinas/metabolismo , Células Dendríticas/fisiología , HumanosRESUMEN
Adjuvants have been considered for a long time to be an accessory and empirical component of vaccine formulations. However, accumulating evidence of their crucial role in initiating and directing the immune response has increased our awareness of the importance of adjuvant research in the past decade. Nevertheless, the importance of adjuvants still is not fully realized by many researchers working in the vaccine field, who are involved mostly in the search for better target antigens. The choice of a proper adjuvant can be determinant for obtaining the best results for a given vaccine candidate, but it is restricted due to intellectual property and know-how issues. Consequently, in most cases the selected adjuvant continues to be the aluminum salt, which has a record of safety, but predominantly constitutes a delivery system (DS). Ideally, new strategies should combine immune potentiators (IP) and DS by mixing both compounds or by obtaining structures that contain both IP and DS. In addition, the term immune polarizer has been introduced as an essential concept in the vaccine design strategies. Here, we review the theme, with emphasis on the discussion of the few licensed new adjuvants, the need for safe mucosal adjuvants and the adjuvant/immunopotentiating activity of conjugation. A summary of toxicology and regulatory issues will also be discussed, and the Finlay Adjuvant Platform is briefly summarized.
Asunto(s)
Humanos , Adyuvantes Inmunológicos/uso terapéutico , Drogas en Investigación , Vacunas/inmunología , Investigación Biomédica/tendenciasRESUMEN
Adjuvants have been considered for a long time to be an accessory and empirical component of vaccine formulations. However, accumulating evidence of their crucial role in initiating and directing the immune response has increased our awareness of the importance of adjuvant research in the past decade. Nevertheless, the importance of adjuvants still is not fully realized by many researchers working in the vaccine field, who are involved mostly in the search for better target antigens. The choice of a proper adjuvant can be determinant for obtaining the best results for a given vaccine candidate, but it is restricted due to intellectual property and know-how issues. Consequently, in most cases the selected adjuvant continues to be the aluminum salt, which has a record of safety, but predominantly constitutes a delivery system (DS). Ideally, new strategies should combine immune potentiators (IP) and DS by mixing both compounds or by obtaining structures that contain both IP and DS. In addition, the term immune polarizer has been introduced as an essential concept in the vaccine design strategies. Here, we review the theme, with emphasis on the discussion of the few licensed new adjuvants, the need for safe mucosal adjuvants and the adjuvant/immunopotentiating activity of conjugation. A summary of toxicology and regulatory issues will also be discussed, and the Finlay Adjuvant Platform is briefly summarized.
Asunto(s)
Adyuvantes Inmunológicos/uso terapéutico , Drogas en Investigación , Vacunas/inmunología , Investigación Biomédica/tendencias , HumanosRESUMEN
Immunotherapy of brain tumors is rapidly emerging as a potential clinical option [1-3]. The quality and magnitude of immune responses evoked by the new generation anti-tumor vaccines is in general highly dependent on the source or choice of peptide antigens, and as well, a suitable immunopotentiator. Poorly immunogenic antigens, such as those present in tumor cell lysates, may not reliably provide stimulation like recombinant or DNA-encoded protein antigens might be expected to. In addition, the efficacy of the vaccine may depend on inherent counteracting measures of the tumor which dampen immune surveillance and immune effector activity triggered by immunization [4]. Our body has many means of limiting an immune response to our own (self) proteins. In particular, patients with gliomas exhibit a broad suppression of cell-mediated immunity [5-8]. Unfortunately, for most tumor vaccines the induction of local or systemic immune effector cells does not necessarily translate into objective clinical responses or increased survival [9]. Here we review immunotherapeutic approaches against gliomas and recent pre-clinical and clinical initiatives based on cellular or active immunization of the patient's immune system using autologous and allogeneic tissues or cultured cells. Available evidence shows that single modality cancer therapies likely remain suboptimal. Combination regimens targeting the immune system at multiple coordinated levels must be developed, and possibly combined with strategies to inhibit immune suppressive factors if significant clinical benefit is to be achieved.
Asunto(s)
Traslado Adoptivo/métodos , Neoplasias Encefálicas/terapia , Vacunas contra el Cáncer/inmunología , Glioma/terapia , Inmunoterapia Activa/métodos , Linfocitos T/trasplante , Animales , Antígenos de Neoplasias/inmunología , Neoplasias Encefálicas/inmunología , Ensayos Clínicos como Asunto , Glioma/inmunología , Humanos , Linfocitos T/inmunología , Trasplante Autólogo , Trasplante HomólogoRESUMEN
Chimerical protein "Q", composed of antigenic ribosomal and histone sequences, in combination with live BCG is a promising canine leishmaniasis vaccine candidate; one of the few vaccine candidates that have been tested successfully in dogs. Unfortunately, live BCG is not an appropriate adjuvant for commercial application due to safety problems in dogs. In order to find a safe adjuvant with similar efficacy to live BCG, muramyl dipeptide, aluminium hydroxide, Matrix C and killed Propionibacterium acnes in combination with either E. coli- or baculovirus-produced recombinant JPCM5_Q protein were tested. Groups of five or seven dogs were vaccinated with six different adjuvant-antigen combinations and challenged with a high dose intravenous injection of Leishmania infantum JPC strain promastigotes. All candidate vaccines proved to be safe, and both humoral and cellular responses to the recombinant proteins were detected at the end of the prime-boost vaccination scheme. However, clinical and parasitological data obtained during the 10 month follow-up period indicated that protection was not induced by either of the six candidate vaccines. Although no direct evidence was obtained, our data suggest that live BCG may have a significant protective effect against challenge with L. infantum in dogs.
Asunto(s)
Antígenos de Protozoos/inmunología , Enfermedades de los Perros/prevención & control , Histonas/inmunología , Vacunas contra la Leishmaniasis/inmunología , Leishmaniasis Visceral/veterinaria , Proteínas Ribosómicas/inmunología , Adyuvantes Inmunológicos , Secuencia de Aminoácidos , Animales , Anticuerpos Antiprotozoarios/inmunología , Secuencia de Bases , Proliferación Celular , Enfermedades de los Perros/inmunología , Perros , Epítopos/inmunología , Femenino , Hipersensibilidad Tardía/inmunología , Leishmania infantum/inmunología , Leishmaniasis Visceral/inmunología , Leishmaniasis Visceral/prevención & control , Activación de Linfocitos/inmunología , Masculino , Datos de Secuencia Molecular , Mycobacterium bovis/inmunología , Proteínas Recombinantes/inmunologíaRESUMEN
Veterinary vaccines currently available in Europe and in other parts of the world are developed by the veterinary pharmaceutical industry. The development of a vaccine for veterinary use is an economic endeavour that takes many years. There are many obstacles along the path to the successful development and launch of a vaccine. The industrial development of a vaccine for veterinary use usually starts after the proof of concept that is based on robust academic research. A vaccine can only be made available to the veterinary community once marketing authorisation has been granted by the veterinary authorities. This review gives a brief description of the regulatory requirements which have to be fulfilled before a vaccine can be admitted to the market. Vaccines have to be produced in a quality controlled environment to guarantee delivery of a product of consistent quality with well defined animal and consumer safety and efficacy characteristics. The regulatory and manufacturing legislative framework in which the development takes place is described, as well as the trend in developments in production systems. Recent developments in bacterial, viral and parasite vaccine research and development are also addressed and the development of novel adjuvants that use the expanding knowledge of immunology and disease pathology are described.
Asunto(s)
Enfermedades de los Animales/prevención & control , Industria Farmacéutica/economía , Vacunas/inmunología , Animales , Industria Farmacéutica/organización & administración , Europa (Continente)RESUMEN
Vaccine adjuvants or immunopotentiators comprise a diverse group of molecules or formulations. Despite a wealth of different candidates, there is a need for better vaccine adjuvants in both veterinary and human medicine. For human vaccines, the immunopotentiator choice has been limited to aluminum salts, until recently. By contrast, a whole range of adjuvants is employed for inactivated veterinary vaccines, due to less stringent safety and regulatory requirements and proven superior vaccine performance. This review highlights recent developments and future trends in immunopotentiators.
Asunto(s)
Adyuvantes Inmunológicos/farmacología , Vacunas , Adyuvantes Inmunológicos/administración & dosificación , Compuestos de Aluminio , Animales , Diseño de Fármacos , Sinergismo Farmacológico , Emulsiones , Predicción , Humanos , Nanopartículas , Vacunas/farmacologíaRESUMEN
As Marek's disease virus continues to evolve towards greater virulence, more efficacious vaccines will be required in the future. We expressed chicken interleukin-2 (IL-2) from a turkey herpesvirus (HVT) in an attempt to increase the efficacy of HVT as a vaccine against Marek's disease. The recombinant IL-2/HVT was safe for in ovo vaccination, although it replicated less in the birds compared with the parent HVT strain. Expression of IL-2 increased the neutralizing antibody response against HVT but did not increase the protection against virulent Marek's disease virus challenge.
Asunto(s)
Pollos/genética , Expresión Génica , Herpesvirus Meleágrido 1/genética , Interleucina-2/metabolismo , Mardivirus/patogenicidad , Enfermedad de Marek/inmunología , Vacunas Virales/inmunología , Animales , Anticuerpos Antivirales/sangre , Embrión de Pollo , Interleucina-2/genética , Interleucina-2/inmunología , Mardivirus/inmunología , Enfermedad de Marek/prevención & control , Enfermedad de Marek/virología , Enfermedades de las Aves de Corral/inmunología , Enfermedades de las Aves de Corral/prevención & control , Enfermedades de las Aves de Corral/virología , Vacunas Virales/efectos adversos , Virulencia , Aumento de PesoRESUMEN
Cysteine peptidases (CPs) have been implicated in various processes central to the pathogenicity of Leishmania parasites, and are thought to be key factors in the host-parasite interaction. In order to fully evaluate the potential of the CPs as vaccine candidates, studies in natural host species are required. In the study we report here, recombinant L. infantum CPs CPA and CPB were used to vaccinate dogs. In order to induce an appropriate response against the antigens, recombinant canine IL-12 was added as an adjuvant either by itself or in combination with Quil A. After vaccination, dogs were given an intravenous challenge with promastigotes of L. infantum JPC strain. In both vaccinated groups (CPs with IL-12 or CPs with IL-12 and Quil A) CP-specific antibodies were detected after vaccination, indicating that there was a reaction to the vaccine. However, all dogs were found parasite-positive and all developed some degree of clinical leishmaniosis. The observed lack of efficacy of the candidate vaccines could be due, completely or in part, to a number of factors associated with the vaccine antigen, the adjuvant or host-parasite interactions. When compared to results from other studies, it seems less likely that the molecular conformation of the rCPs or rIL-12 caused this lack of efficacy. More plausible explanations are the dose and timing of the IL-12 application and the potentially different effects IL-12 induces as an adjuvant in either the murine or the canine leishmaniosis model.
Asunto(s)
Cisteína Endopeptidasas/administración & dosificación , Interleucina-12/administración & dosificación , Leishmania infantum/inmunología , Leishmaniasis Visceral/prevención & control , Vacunas de ADN/inmunología , Adyuvantes Inmunológicos/administración & dosificación , Animales , Cisteína Endopeptidasas/inmunología , Enfermedades de los Perros , Perros , Interleucina-12/inmunología , Leishmaniasis Visceral/inmunología , Vacunas Antiprotozoos/administración & dosificación , Vacunas Antiprotozoos/química , Vacunas Antiprotozoos/inmunología , Vacunación , Vacunas de ADN/administración & dosificación , Vacunas de ADN/químicaRESUMEN
Poorly immunogenic antigens depend on vaccine adjuvants to evoke an immune response. In addition, adjuvants largely determine the magnitude, quality, time of onset and the duration of immune responses to co-administered antigens. As late as 1989, Janeway aptly called adjuvants: "the immunologist's dirty little secret". This statement reflected the ignorance on the mechanisms of action of most known adjuvants. Yet, rational vaccine design involves a logical choice of adjuvant based on a knowledge of their mode of action and their effects on product efficacy and safety. However, even today the key processes critical for immune induction in general and those evoked by vaccine adjuvants in particular are being disputed among immunologists. This paper presents the four most important concepts likely to explain some of the mechanisms of vaccine adjuvants. They include: (i) the geographical concept of immune reactivity; (ii) the depot concept; (iii) the hypothesis of pathogen-structure recognition, and (iv) the damage/endogenous danger theory. These paradigms are based on observations gathered in mammalian species, largely in murine models. In aquatic animals the processes underlying immune induction will at least partly overlap those in mammals. However, due to inherent species differences, certain pathways may be different. Rational vaccine design, a difficult goal in mammals, is further hampered in aquatic animals by the lack of immunological tools in these species. Extensive trial and error-based approaches have yielded adjuvant candidates for various fish species, with acceptable safety and proven efficacy, some of which are presented.
Asunto(s)
Adyuvantes Inmunológicos/metabolismo , Antígenos/metabolismo , Acuicultura/métodos , Diseño de Fármacos , Transducción de Señal/inmunología , Vacunas , Adyuvantes Inmunológicos/fisiología , Animales , Células Presentadoras de Antígenos/metabolismo , Antígenos/inmunología , Geografía , Activación de Linfocitos/inmunología , Especificidad de la EspecieRESUMEN
Successful vaccination against infectious or neoplastic disease programs the host's immune system, in a multistep process, to generate an efficient defense and memory response. Conditioning of immune responses to nonreplicating, poorly immunogenic antigens generally requires the help of an adjuvant. The present review attempts to classify vaccine adjuvants functionally, according to recently proposed, mutually exclusive concepts of immunity induction. These include the geographical concept of immune reactivity and the theory of depot effect. Both emphasize the importance of antigen delivery and localization to the lymph node in time after immunization. Other concepts stress the importance of key signals, such as "infectious nonself" or "danger," which influence the activation state of the antigen-presenting cell (APC) and, hence, its capacity to prime naïve T cells. The nature of adjuvant-induced immune responses is discussed in relation to each concept.
Asunto(s)
Adyuvantes Inmunológicos/farmacología , Vacunas/inmunología , Animales , Células Presentadoras de Antígenos/inmunología , Antígenos/administración & dosificación , Antígenos/inmunología , Antígenos/metabolismo , Citocinas/fisiología , Células Dendríticas/inmunología , Diseño de Fármacos , Humanos , Inmunidad , Linfocitos T/inmunología , Vacunas/administración & dosificaciónRESUMEN
Interleukin-12 (IL-12) is a key cytokine in the development of cell-mediated immune responses. Bioactive IL-12 is a heterodimeric cytokine composed of disulphide linked p35 and p40 subunits. The aim of this study was to verify biologically activity of the products expressed from equine interleukin-12 (IL-12) p35 and p40 cDNAs and to establish whether equine IL-12 could be expressed as a p35/p40 fusion polypeptide, as has been reported for IL-12a of several mammalian species. We report production of equine IL-12 through expression of p35 and p40 subunits in mammalian and insect cells and of a p35:p40 fusion polypeptide in mammalian cells. Conditioned medium recovered from cultures transiently transfected with constructs encoding equine p35 and p40 subunits or single chain IL-12 enhanced IFN-gamma production in cells derived from equine lymph nodes. Preincubation of IFN-gamma inducing preparations with anti-p40 monoclonal antibody resulted in a significant decrease in IFN-gamma induction capacity. Medium recovered from p35 and p40-expressing baculovirus infected cultures enhanced target cell IFN-gamma production and proliferation. Experimental studies in mice and other animals have revealed a therapeutic benefit of IL-12 in cancer, inflammatory and infectious disease and an adjuvant effect in prophylactic regimes. Production of a bioactive species-specific IL-12 is a first step towards an investigation of its potential application in equine species.
Asunto(s)
Caballos/inmunología , Interferón gamma/biosíntesis , Interleucina-12/biosíntesis , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/inmunología , Baculoviridae , Línea Celular , ADN Complementario/genética , Regulación de la Expresión Génica , Vectores Genéticos , Enfermedades de los Caballos/inmunología , Enfermedades de los Caballos/terapia , Caballos/genética , Inmunidad Celular , Interleucina-12/química , Interleucina-12/genética , Interleucina-12/inmunología , Subunidad p35 de la Interleucina-12 , Subunidad p40 de la Interleucina-12 , Datos de Secuencia Molecular , Subunidades de Proteína , SpodopteraRESUMEN
In the present study we assessed the capacity of recombinant E. coli- or plasmid-expressed chicken interferons (IFN) and chicken IL-1beta, to exert immunostimulatory activities for humoral immune responses, in day-old and adult chickens. We observed that both recombinant E. coli-expressed chicken IFN-alpha/beta and IFN-gamma facilitated the induction of a primary and also a secondary antibody response, using tetanus toxoid (TT) as a bacterial model antigen, in immunologically mature 3-week-old chickens. In contrast, no improvement of antibody either type of chicken IFN was co-injected with inactivated Infectious Bursal Disease Virus (IBDV) antigen. TT-specific antibody formation was marginally increased by co-injection of recombinant E. coli-expressed chicken IL-1beta. Combined administration of IFN-alpha/beta plus IFN-gamma or IL-beta increased responses to TT in an additive, but not synergistic fashion. Remarkably, no augmentation of antibody responses specific for TT, nor IBDV, was noted in day-old birds, receiving IFN-alpha/beta or IFN-gamma as adjuvant. Also, intramuscular immunization of 3-week-old birds, using plasmids encoding IFN-alpha/beta together with TT protein antigen, significantly increased the speed and magnitude of TT-specific antibody responses. Plasmids encoding chicken IL-beta or IFN-gamma had a minimal or inhibitory effect, respectively. These data indicate a potential for chicken cytokines as immunoadjuvant for particular types of chicken vaccine antigens.
Asunto(s)
Adyuvantes Inmunológicos , Anticuerpos Antibacterianos/biosíntesis , Anticuerpos Antivirales/biosíntesis , Pollos/inmunología , Virus de la Enfermedad Infecciosa de la Bolsa/inmunología , Interferón-alfa/inmunología , Interferón gamma/inmunología , Interleucina-1/inmunología , Toxoide Tetánico/inmunología , Vacunas Virales/inmunología , Factores de Edad , Animales , Pollos/crecimiento & desarrollo , Clostridium tetani/inmunología , Escherichia coli/metabolismo , Femenino , Inyecciones Intramusculares , Interferón-alfa/genética , Interferón gamma/genética , Interleucina-1/genética , Plásmidos/genética , Proteínas Recombinantes/inmunología , Organismos Libres de Patógenos Específicos , Toxoide Tetánico/administración & dosificación , VacunaciónRESUMEN
The importance of each of the two interferon (IFN) systems in impeding herpesvirus replication and in stimulating virus-specific lymphocytes to control an acute systemic infection is not completely understood. To further our knowledge, pseudorabies virus, attenuated by deletion of the glycoprotein E gene to impair its neurovirulence and by deletion of the thymidine kinase gene (gE-TK-PRV), was used to infect wild-type 129Sv/Ev and congenic mice with immune system-associated genetic deficiencies. Mice with mature B and T lymphocytes but lacking either one or both functional receptors for members of each of the two IFN families were infected with gE-TK-PRV. At 3 and 7 but not 14 days after infection, replicating gE-TK-PRV could be isolated only from livers or spleens of mice lacking the receptors for both IFN families, and these mice survived the infection. Therefore, functional IFN receptors were not required to induce a protective immune response against an acute infection with gE-TK-PRV. Furthermore, PRV-specific antibodies of all immunoglobulin G isotypes were produced in these mice. Mice without mature B and T lymphocytes and lacking either one or both functional receptors for members of each of the two IFN families were also infected with gE-TK-PRV. Three days after infection, replicating virus could be isolated only from mice lacking both mature B and T lymphocytes and functional IFN receptors, and these mice were not able to clear the virus. We present evidence that mice with an intact gamma IFN system but without mature B and T cells were able to prevent systemic dissemination of gE-TK-PRV.
Asunto(s)
Interferones/fisiología , Seudorrabia/inmunología , Animales , Anticuerpos Antivirales/biosíntesis , Citocinas/biosíntesis , Citocinas/sangre , Proteínas de Unión al ADN/fisiología , Femenino , Inmunoglobulina G/biosíntesis , Masculino , Ratones , Receptores de Interferón/fisiología , Timidina Quinasa/genética , Proteínas del Envoltorio Viral/genética , Replicación ViralRESUMEN
We analysed the ability of a plasmid carrying the gene encoding glycoprotein D (gD) of pseudorabies virus (PRV) to induce humoral and cell-mediated immune responses and assessed the protection provided by PRV-gD DNA vaccination against challenge infection with PRV. Immunization with plasmid PRV-gD induced neutralizing antibodies and lymphocyte proliferative responses both in mice and pigs. Moreover, when challenged with virulent PRV six weeks following the last immunization, PRV-gD DNA vaccinated pigs excreted virus for a significantly shorter period and showed less clinical symptoms than pigs vaccinated with a control plasmid. Thus, in the target animal, DNA vaccination with PRV-gD DNA induces protective immunity against challenge infection.
Asunto(s)
Herpesvirus Suido 1/inmunología , Seudorrabia/prevención & control , Vacunación/veterinaria , Vacunas de ADN , Proteínas del Envoltorio Viral/genética , Animales , Clonación Molecular , Femenino , Herpesvirus Suido 1/genética , Células L , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Plásmidos , Porcinos , Vacunas de ADN/inmunología , Proteínas del Envoltorio Viral/inmunologíaRESUMEN
A culture of bone marrow cells from the femurs of canine pups at high concentrations of fetal calf serum under non-adherent conditions allowed the proliferation and differentiation of mononuclear phagocyte lineage cells, as evidenced by morphology and CD14 expression. Cells from other lineages progressively diminished in numbers. Cells collected between 12 and 19 days of culture expressed an array of macrophage activities including ingestion of opsonised erythrocytes, generation of superoxide, up-regulation of procoagulant activity and synthesis of tumour necrosis factor (TNF) upon appropriate stimulation. TNF production was enhanced when the cultures were simultaneously stimulated with canine recombinant, or supernatant-derived, interferon-gamma. In contrast, low levels of inducible nitric oxide (NO) synthase were expressed by only a minority of stimulated macrophages, and nitrite could not be detected in the medium. Therefore, canine macrophages generated by this novel culture system resemble human macrophages in their inefficient and restricted generation of NO upon appropriate stimulation.
Asunto(s)
Células de la Médula Ósea/citología , Macrófagos/citología , Macrófagos/fisiología , Animales , Animales Recién Nacidos , Técnicas de Cultivo de Célula/métodos , Células Cultivadas , Perros , Fémur , Citometría de Flujo , Granulocitos/citología , Humanos , Mediciones Luminiscentes , Linfocitos/citología , Activación de Macrófagos/efectos de los fármacos , Macrófagos/inmunología , Monocitos/citología , Óxido Nítrico/biosíntesis , Óxido Nítrico Sintasa/biosíntesis , Óxido Nítrico Sintasa de Tipo II , Acetato de Tetradecanoilforbol/farmacología , Transcripción Genética , Factor de Necrosis Tumoral alfa/biosíntesisRESUMEN
Studies in IL-12-deficient mice established the necessity for IL-12 to generate a Th1 cytokine response that is often required for elimination of intracellular pathogens. In this study, we demonstrate that mice with a targeted disruption of the IL-12p40 and/or p35 gene effectively control liver damage induced by mouse hepatitis virus (MHV) infection, similar to wild-type animals. In contrast, MHV-infected IFN-gamma receptor-deficient (IFN-gammaR[-/-]) mice showed an increased susceptibility to coronaviral hepatitis. Surprisingly, MHV-infected mice lacking IL-12 produced a polarized Th1-type cytokine response, as evidenced by high IFN-gamma and nondetectable IL-4 production by CD4+ splenocytes and normal virus-specific serum IgG2a/IgG1 ratios. The virus-induced type 1 cytokine secretion pattern was not reversed in IL-12-deficient mice by in vivo neutralization of IFN-gamma nor in IFN-gammaR(-/-) mice receiving IL-12-neutralizing Abs. In IL-12-deficient mice, Th1-type responses were also generated upon immunization with inactivated MHV. In contrast, following immunization with keyhole limpet hemocyanin, mice lacking IL-12 mounted strongly reduced specific IgG2a and increased IgE responses, indicative of a type 2-dominated cytokine pattern. These findings demonstrate that following a virus infection, IL-12 is not essential for the generation of polarized T cell type 1 cytokine expression and associated immune responses, which is in marked contrast to nonviral systems. Our data suggest that viruses may selectively induce IFN-gamma production and Th1-type immune reactions even in the absence of IL-12.
Asunto(s)
Infecciones por Coronavirus/inmunología , Interleucina-12/deficiencia , Virus de la Hepatitis Murina , Células TH1/inmunología , Animales , Infecciones por Coronavirus/etiología , Inmunoglobulina G/biosíntesis , Interferón gamma/biosíntesis , Interleucina-12/genética , Interleucina-12/fisiología , Interleucina-4/biosíntesis , Ratones , Ratones Noqueados , Virus de la Hepatitis Murina/inmunología , Virus de la Hepatitis Murina/patogenicidad , Virus de la Hepatitis Murina/fisiología , Pruebas de Neutralización , Replicación ViralRESUMEN
We analysed the production of transforming growth factor beta (TGF-beta) during a cytomegalovirus (CMV) infection in a rat model system. Splenocytes from immunocompetent rats infected with rat CMV (RCMV) released increased amounts of TGF-beta1. TGF-beta production was also evident in RCMV-infected radiation-immunosuppressed rats; their sera inhibited the interleukin 2-induced proliferation of T cells, which could be restored by anti-TGF-beta antibodies. In addition, TGF-beta production could be visualized immunohistologically in the lungs, spleen, liver and bone marrow of radiation-immunosuppressed infected rats. The virus directly induced this cytokine since TGF-beta was produced upon RCMV infection in vitro. The induction of TGF-beta production may contribute to immunosuppression during CMV infection.