RESUMEN
BACKGROUND: Tuberculosis (TB) is a major health problem worldwide. In TB, the immune and central nervous systems modulate each other. The two main components of this network are the hypothalamic-pituitary-adrenal axis (HPA) and autonomic nervous system (ANS). OBJECTIVE: To elucidate neuro-endocrine-immune (NEI) interactions in pulmonary (PTB) or pleural (PLTB) TB, we analysed the relationship among compounds from these systems. METHODS: We quantified levels of catecholamines, hormones and cytokines in plasma from patients with PTB (n = 46) or PLTB (n = 12) and controls (n = 32), and in the pleural fluid from PLTB patients. Transcript expression for genes involved in glucocorticoid-related function (quantitative real-time polymerase chain reaction) was also analysed in mononuclear cells (MCs) from peripheral blood (PBMC) or pleural effusion (PEMC) compartments. RESULTS: Both patient groups had increased plasma levels of pro- and anti-inflammatory cytokines, cortisol, growth hormone (GH) and dopamine, whereas insulin-like growth factor 1 (IGF-1) and dehydroepiandrosterone levels were decreased. The pleural fluid contained increased levels of pro-inflammatory cytokines, GH and IGF-1 and reduced levels of steroid hormones compared with their plasma counterparts. PBMCs from PTB patients had increased expression of transcripts for 11ß-hydroxysteroid dehydrogenase (11ßHSD1) and a decreased glucocorticoid receptor (GR) ratio (GRα/GRß). In PLTB cases, expression of 11ßHSD1 and GRα transcripts was higher in PEMCs. CONCLUSION: PTB patients seem to display adverse NEI dysregulation. Changes in pleural fluid are compatible with a more effective NEI reaction.
Asunto(s)
Sistemas Neurosecretores/inmunología , Tuberculosis Pleural/inmunología , Tuberculosis Pulmonar/inmunología , Adulto , Estudios de Cohortes , Citocinas/análisis , Femenino , Humanos , Factor I del Crecimiento Similar a la Insulina/análisis , Leucocitos Mononucleares/metabolismo , Masculino , Persona de Mediana Edad , Derrame Pleural/metabolismo , Receptores de Glucocorticoides/metabolismo , Tuberculosis Pleural/sangre , Tuberculosis Pulmonar/sangre , Adulto JovenAsunto(s)
Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , /complicaciones , /inmunología , /metabolismo , Tuberculosis , ResúmenesAsunto(s)
Humanos , Trypanosoma cruzi , Homeostasis , Linfocitos T Reguladores , Enfermedades Parasitarias , Timo , Apoptosis , Diferenciación CelularRESUMEN
Diabetes is a risk factor for the development of pulmonary tuberculosis (TB) and both diseases present endocrine alterations likely to play a role in certain immuno-endocrine-metabolic associated disorders. Patients with TB, or with TB and type 2 diabetes (TB + T2DM) and healthy controls (HCo) were assessed for plasma levels of cortisol, dehydroepiandrosterone (DHEA), estradiol, testosterone, growth hormone (GH), prolactin, insulin-like growth factor-1 (IGF-1), cytokines (IL-6, IL-10, IFN-γ) and the specific lymphoproliferative capacity of peripheral blood mononuclear cells. All patients had higher levels of cortisol with a reduction in DHEA, thus resulting in an increased cortisol/DHEA ratio (Cort/DHEA). Increased prolactin and particularly GH levels were found in both groups of TB patients. This was not paralleled by increased concentrations of IGF, which remained within the levels of HCo. Estradiol levels were significantly augmented in patients TB, and significantly more in TB + T2DM, whereas testosterone levels were decreased in both groups of patients. IFN- γ and IL-6 concentrations were significantly increased in all TB, even further in TB + T2DM; while IL-10 was equally increased in both groups of TB patients. The in vitro specific proliferative capacity was decreased in both groups of patients as compared to that of HCo. The adverse immune-endocrine profile of TB seems to be slightly more pronounced in patients who also have T2DM.
Asunto(s)
Citocinas/sangre , Diabetes Mellitus Tipo 2/sangre , Hormonas/sangre , Infecciones Oportunistas/sangre , Tuberculosis Pulmonar/sangre , Adulto , Estudios de Casos y Controles , Células Cultivadas , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/inmunología , Femenino , Humanos , Activación de Linfocitos , Masculino , Persona de Mediana Edad , Infecciones Oportunistas/complicaciones , Infecciones Oportunistas/inmunología , Tuberculosis Pulmonar/complicaciones , Tuberculosis Pulmonar/inmunologíaRESUMEN
BACKGROUND: Tuberculosis (TB) is a infectious disease characterised by a profound immune-endocrine metabolic imbalance, including a diminution in leptin plasma levels. Leptin appears to be the link between nutritional status and the development of a protective immune response. OBJECTIVE: To examine the effects of leptin on the proliferation and production of interferon-gamma (IFN-γ) by peripheral blood mononuclear cells (PBMC) in TB patients and healthy controls stimulated with mycobacterial antigens with or without leptin. As macrophages are key cells in mycobacterial containment, the effect of leptin on the production of interleukin (IL) 1ß and IL-1Ra by the monocytic cell line THP-1 was also studied. RESULTS: Leptin diminished the proliferative capacity of PBMC on mycobacterial stimulation, and had no effect on IFN-γ production in terms of measurements in culture supernatants or intracytoplasmic analysis using flow cytometry. Real-time polymerase chain reaction studies of PBMC from TB patients revealed a preserved expression of leptin receptor. Furthermore, IL-1ß and IL-1Ra secretion by THP-1 cells was not modified by leptin treatment. CONCLUSION: The study results do not support the utility of treatment with leptin to correct immune imbalances due to TB.
Asunto(s)
Antígenos Bacterianos/inmunología , Interferón gamma/inmunología , Leptina/farmacología , Tuberculosis/inmunología , Adulto , Estudios de Casos y Controles , Línea Celular , Femenino , Humanos , Inmunidad Celular , Proteína Antagonista del Receptor de Interleucina 1/metabolismo , Interleucina-1beta/metabolismo , Leucocitos Mononucleares/inmunología , Masculino , Monocitos/efectos de los fármacos , Monocitos/inmunología , Mycobacterium tuberculosis/inmunología , Reacción en Cadena en Tiempo Real de la Polimerasa , Adulto JovenRESUMEN
We studied the features of parallel immunoneuroendocrine responses in patients with different degrees of chronic Chagas myocarditis (indeterminate, mild/moderate or severe). A systemic inflammatory scenario was evident in patients with severe myocarditis compared to healthy subjects. This was paralleled by a disrupted activation of the hypothalamus-pituitary-adrenal axis, characterized by decreased concentrations of dehydroepiandrosterone-sulfate (DHEA-s) and an unbalanced cortisol/DHEA-s ratio, reinforcing the view that severe Chagas disease is devoid of an adequate anti-inflammatory milieu, likely involved in pathology. Our study constitutes the first demonstration of neuroendocrine disturbances, in parallel to a systemic inflammatory profile, during progressive human Chagas disease.
Asunto(s)
Enfermedad de Chagas/inmunología , Enfermedad de Chagas/patología , Progresión de la Enfermedad , Mediadores de Inflamación/fisiología , Adulto , Enfermedad de Chagas/metabolismo , Enfermedad Crónica , Femenino , Hormona de Crecimiento Humana/fisiología , Humanos , Interleucina-17/fisiología , Interleucina-6/fisiología , Masculino , Persona de Mediana Edad , Células Neuroendocrinas/inmunología , Células Neuroendocrinas/metabolismo , Células Neuroendocrinas/patología , Factor de Necrosis Tumoral alfa/fisiologíaRESUMEN
Tumour necrosis factor (TNF)-alpha is crucial for resistance to Trypanosoma cruzi acute infection, but there is scant information on its role during the chronic phase. To address this issue, we analysed whether a short treatment with a TNF-alpha blocker affected the course and characteristics of chronic disease in a rat experimental model of T. cruzi infection. An anti-TNF-alpha agent (infliximab) was administered during the chronic phase for a period of 4 weeks (3 mg/kg/week), while control infected rats were inoculated with saline physiological solution. Search for parasites yielded non-successful results in all infected groups, irrespective of treatment. Nevertheless, the presence of T. cruzi kDNA in heart tissue was detected in infected and infected plus treated animals. Because infliximab might induce changes in the anti-parasite cytokine response, circulating levels of interleukin (IL)-10, interferon-gamma and nitric oxide were evaluated. An increase in IL-10 levels was observed only in the infected group treated with the anti-TNF-alpha blocker compared to the remaining groups (P < 0.05). A clear attenuation of histological damage associated with a diminution of cardiac TNF-alpha mRNA expression was observed in the infected and treated animals compared to the infected and non-treated group. Blocking of TNF-alpha during a relatively short period in chronically infected rats did not lead to evident parasite reactivation but reduced myocarditis severity significantly, indicating a role of this cytokine in the pathogenesis of chronic myocardial damage.
Asunto(s)
Anticuerpos Monoclonales/uso terapéutico , Cardiomiopatía Chagásica/tratamiento farmacológico , Inmunosupresores/uso terapéutico , Trypanosoma cruzi , Factor de Necrosis Tumoral alfa/antagonistas & inhibidores , Animales , Anticuerpos Monoclonales/farmacología , Anticuerpos Antiprotozoarios/inmunología , ADN Protozoario/análisis , Corazón/parasitología , Inmunohistoquímica , Inmunosupresores/farmacología , Infliximab , Masculino , Modelos Animales , Parasitemia/diagnóstico , ARN Mensajero/análisis , Distribución Aleatoria , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Trypanosoma cruzi/genética , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/inmunologíaRESUMEN
Based on a unifying theory presented here, it is predicted that the immune defects resulting in chronic inflammation rather than effective immune responses could be rectified by the therapeutic use of agents prepared from micro-organisms. With appropriate molecular patterns, these should be able to induce protective immunoregulatory networks or to reprogramme defective ones. In contrast to acute inflammation, chronic inflammation appears to have no beneficial role, but is a state of sustained immune reactivity in the presence or progression of a disease process. This results in an escalating cycle of tissue damage followed by unproductive tissue repair, breaks in self-tolerance, malignant transformation or deleterious changes in tissue morphology and function. Such inappropriate immune reactivity is an underlying characteristic, either in initiation or maintenance, of a diverse range of disease states including chronic infection, autoimmunity, allergy, cancer, vascular disease and metabolic alterations. Evidence is presented that the inappropriate immune reactivity is due, at least to some extent, to failures in the establishment of immunoregulatory networks as a result of hygiene-related factors. Such networks are the result of activation of antigen-presenting cells, principally dendritic cells, by molecular patterns of micro-organisms encountered sequentially during life and establishing the 'biography' of the immune system.
Asunto(s)
Productos Biológicos/uso terapéutico , Inflamación/inmunología , Animales , Autoinmunidad/inmunología , Productos Biológicos/inmunología , Enfermedad Crónica , Células Dendríticas/inmunología , Progresión de la Enfermedad , Humanos , Infecciones/inmunología , Infecciones/terapia , Inflamación/terapiaRESUMEN
A heat-killed preparation of Mycobacterium vaccae (SRL172) has been shown, in recent studies, to be effective in the treatment of adenocarcinoma of the lung and renal cell cancer. It is postulated that the mechanisms of this form of immunotherapy is, at least in part, due to immune regulation, reflected in the selective enhancement of Th1 and down-regulation of Th2 T cell activity. These beneficial effects are attributed to the ability of adjuvants in the bacterial cell walls to modify and optimise the response to antigens shared by the bacteria and stressed host tissues, resulting in the destruction of cancer cells by programmed cell death or apoptosis. The M. vaccae-induced apoptosis appears to be most effective against carcinomas, perhaps especially those of glandular tissue, in contrast to pyrexia-induced necrosis which is most effective against tumours of mesodermal origin. In view of the great range of adjuvants, especially in the genus Mycobacterium and related genera, it may prove possible to develop a range of immunotherapeutic agents with useful activity against a wide range of cancers.
Asunto(s)
Adyuvantes Inmunológicos/uso terapéutico , Inmunoterapia/métodos , Mycobacterium/inmunología , Neoplasias/tratamiento farmacológico , Antígenos de Neoplasias/inmunología , Antineoplásicos/uso terapéutico , Citotoxicidad Inmunológica , Humanos , Neoplasias/inmunologíaRESUMEN
BACKGROUND AND OBJECTIVES: Conventional serology tests for Trypanosoma cruzi blood banks screening are neither sensitive nor specific enough, and currently no gold standard assay is available. Trans-sialidase inhibition assay (TIA) detects neutralizing antibodies against T. cruzi trans-sialidase. Conventional serology inconclusive, positive and negative blood donor samples were evaluated by employing TIA as a supplementary test. MATERIALS AND METHODS: Three hundred and twenty-one blood donor samples were tested using a combination of assays. Based on the results of testing, these were divided into a number of groups. All samples were tested by TIA. RESULTS: In conventional serology inconclusive samples 48.1% were TIA-positive, 1/54 conventional serology positive samples was TIA-negative. All negative samples from donors without epidemiological risks were TIA-negative; 1/48 was positive in those with epidemiological risk. CONCLUSION: Trans-sialidase inhibition assay application in blood banks may be useful to resolve inconclusive samples, and thus improves donor counseling and allows individual re-entry. The use of TIA in samples from negative conventional test donors but positive epidemiological antecedents may contribute to decrease transfusional risk.
Asunto(s)
Almacenamiento de Sangre/métodos , Donantes de Sangre , Enfermedad de Chagas/sangre , Selección de Donante/métodos , Glicoproteínas/sangre , Neuraminidasa/sangre , Proteínas Protozoarias/sangre , Trypanosoma cruzi/enzimología , Argentina , Enfermedad de Chagas/enzimología , Enfermedad de Chagas/prevención & control , Enfermedad de Chagas/transmisión , Glicoproteínas/antagonistas & inhibidores , Humanos , Neuraminidasa/antagonistas & inhibidores , Proteínas Protozoarias/antagonistas & inhibidores , Estudios RetrospectivosRESUMEN
Tuberculosis (TB) may be regarded as a disease in which the immune response to Mycobacterium tuberculosis, its etiologic agent, is engaged both in protection and pathology. Different T-lymphocyte subsets are involved in the immune response against M. tuberculosis, but production of interferon-gamma (IFN-gamma) by T cells seems to be fundamental for disease control. Th1-type cytokine responses predominate in patients with mild or moderate forms of pulmonary TB, whereas the production of Th2-type cytokines prevails in the severe disease. Since the immune response fails to definitely eradicate the pathogen, a chronic infection is established, and it is likely that a broad range of regulatory mechanisms operate in this situation. Cytokines released during the course of an immune response activate the hypothalamus-pituitary-adrenal axis leading to the production of glucocorticoids and dehydroepiandrosterone (DHEA), with known immunomodulatory effects. TB patients exhibit increased concentrations of interleukin-6 and cortisol in plasma, reduced DHEA and testosterone levels, together with remarkably increased growth hormone concentrations that were not accompanied by an expected raise in insulin-like growth factor-1. Significant increases in estradiol, prolactin, and thyroid hormone concentrations were also detected in patients. Cortisol inhibits the mycobacterial antigen-driven proliferation and IFN-gamma production, whereas DHEA suppresses transforming growth factor beta production by lymphoid cells from TB patients with advanced disease. Furthermore, supernatants from cultures of M. tuberculosis-stimulated mononuclear cells of TB patients inhibit DHEA secretion by a human adrenal cell line. This type of immuno-endocrine interactions may affect the control of tissue damage and the development of protective immune responses, partly accounting for disease aggravation.
Asunto(s)
Sistemas Neurosecretores/inmunología , Sistemas Neurosecretores/metabolismo , Tuberculosis Pulmonar/inmunología , Tuberculosis Pulmonar/metabolismo , Animales , Citocinas/metabolismo , Citocinas/fisiología , Humanos , Tuberculosis Pulmonar/microbiología , Tuberculosis Pulmonar/patologíaRESUMEN
We have investigated the relationship between cortisol and dehydroepiandrosterone (DHEA) levels and the immune response to mycobacterial antigens in peripheral venous blood, from a male population of active tuberculosis patients and age-matched healthy controls of the same sex (HCo). Peripheral blood mononuclear cells were cultured for 36 or 96 h with whole sonicated Mycobacterium tuberculosis (WSA) for measurement of proliferation, interferon gamma (IFN-gamma) and interleukin-10 (IL-10) in culture supernatants. Comparisons on the in vitro mycobacterial-driven immune responses demonstrated that TB patients had a higher IL-10 production, a decreased lymphoproliferation and a trend to reduced IFN-gamma synthesis, in relation to HCo. Active disease was also characterized by increases in the plasma levels of glucocorticoids (GC) and reduced concentrations of DHEA which resulted in a higher cortisol/DHEA ratio respect the HCo group. Plasma DHEA levels were positively correlated with IFN-gamma values. An inverse correlation was found between the cortisol/DHEA ratio and IFN-gamma levels. Novel evidence is provided showing that the balance between cortisol and DHEA is partly responsible for the immune perturbations seen in TB patients.
Asunto(s)
Citocinas/biosíntesis , Deshidroepiandrosterona/sangre , Hidrocortisona/sangre , Leucocitos Mononucleares/metabolismo , Tuberculosis Pulmonar/sangre , Tuberculosis Pulmonar/inmunología , Proliferación Celular , Humanos , Leucocitos Mononucleares/inmunología , Activación de Linfocitos/inmunología , Masculino , Persona de Mediana Edad , Mycobacterium tuberculosis/inmunologíaRESUMEN
The well-established model of Chagas' disease in "l" rats was used to evaluate the effects of three injections of heat-killed Gordonia bronchialis, Rhodococcus coprophilus or saline on Trypanosoma cruzi parasitaemia and acute and chronic myocarditis, sequelae of the infection. Two vaccinating injections were given prior to challenge with T. cruzi, and the third, immunotherapeutic, injection was given 7 days after challenge. Treatment with either actinomycete significantly reduced acute parasitaemia (p<0.04), modified cellular infiltration during acute myocarditis and limited chronic myocarditis (p<0.03) in comparison with the saline-treated control animals. Immunological investigations showed that both bacterial preparations achieved their results through different mechanisms. The relevance of our findings to human Chagas' disease is discussed.
Asunto(s)
Actinomycetales/inmunología , Enfermedad de Chagas/inmunología , Inmunización , Animales , Anticuerpos Antiprotozoarios/sangre , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Cardiomiopatía Chagásica/inmunología , Microbiología Ambiental , Inmunoglobulina G/sangre , Masculino , Parasitemia/prevención & control , Ratas , SuspensionesRESUMEN
Peripheral blood mononuclear cells taken from 32 patients with Rheumatoid Arthritis (RA) receiving neither steroids nor methotrexate and 34 healthy controls were examined for lymphoproliferation in the presence of ultrasonic extracts of 14 different mycobacterial species or serotypes, of an extract of Candida albicans and of 2 mitogens. Additionally, cells were incubated for 96 hours alone, or with Mycobacterium tuberculosis (M.tb) sonicate or Concanavalin-A (Con-A), and supernatants were tested for a range of cytokines. Lymphocytes of rheumatoid patients were less reactive than controls to all the mycobacterial preparations, but no different in their responses to mitogens. Stimulation of patients' cells with M.tb sonicate induced significantly less interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) but more transforming growth factor- beta (TGF-beta) than controls. Even stimulation with Con-A induced much less IFN-gamma in patient's cells than in those of controls. The combination of reduced responses to the mycobacterial reagents and reduced stimulation of type 1 cytokines by the sonicate of M.tb, suggests reduced responsiveness to group i, common mycobacterial antigens. Such findings need not indicate involvement of mycobacteria specifically in the disease aetiology, but provide novel information on the immunopathological abnormalities, which may explain the reported increased susceptibility to mycobacteria of RA patients.
Asunto(s)
Artritis Reumatoide/inmunología , Citocinas/biosíntesis , Inflamación/sangre , Interferón gamma/biosíntesis , Leucocitos/microbiología , Mycobacteriaceae/inmunología , Adulto , Candida albicans/inmunología , Epítopos , Femenino , Humanos , Técnicas In Vitro , Mononucleosis Infecciosa/inmunología , Activación de Linfocitos/efectos de los fármacos , Masculino , Persona de Mediana Edad , Mitógenos/inmunología , Linfocitos T/inmunologíaRESUMEN
Earlier work in Trypanosoma cruzi-infected C57BL/6 and BALB/c mice revealed an acute disease, of lethal outcome in the former group and lesser severity in BALB/c mice. Fatal course was not accompanied by an increased parasite load, but by a substantial imbalance between pro- and anti-inflammatory cytokine serum levels. To better characterise the mechanisms allowing the host to restrain the infection, we have now studied the specific IgG production and in vitro behaviour of peritoneal macrophages (PMs) when exposed to T. cruzi. BALC/c mice displayed higher serum levels of specific immunoglobulins in the first weeks of acute infection. In vitro infected PMs showed no between-group differences in the number of intracellular parasites, although TNFalpha levels were significantly higher in culture supernatants from C57BL/6 mice. Because an LPS-based pretreatment (desensitisation protocol followed by a sublethal LPS dose) reduced disease severity of C57BL/6 mice, we next explored the features of the in vitro infection in PMs from mice subjected to such protocol. PMs from LPS-pretreated mice had a decreased production of TNFalpha and IL-1beta, becoming more permissive to parasite replication. It is concluded that deficient control of T. cruzi infection in C57BL/6 mice may also involve a less satisfactory specific IgG response and increased TNFalpha production by PMs. Improved disease outcome in LPS-pretreated mice may be associated with the reduced inflammatory cytokine production by PMs, but the impaired ability of these cells to control parasite growth suggests that compensatory mechanisms are operating in the in vivo situation.
Asunto(s)
Enfermedad de Chagas/inmunología , Citocinas/metabolismo , Inmunoglobulina G/inmunología , Macrófagos Peritoneales/metabolismo , Trypanosoma cruzi/inmunología , Animales , Citocinas/inmunología , Cartilla de ADN , Ensayo de Inmunoadsorción Enzimática , Técnica del Anticuerpo Fluorescente Indirecta , Interleucina-1/inmunología , Interleucina-1/metabolismo , Lipopolisacáridos , Macrófagos Peritoneales/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estadísticas no Paramétricas , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/inmunología , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
The effect of cortisol and/or dehydroepiandrosterone (DHEA) on the immune response to antigens obtained from Mycobacterium tuberculosis was studied in vitro by using peripheral blood mononuclear cells obtained from patients at various stages of lung tuberculosis (TB) and from healthy control people (HCo). The results obtained show for the first time that addition of cortisol within concentrations of physiological range can inhibit the mycobacterial antigen-driven proliferation of cells from HCo and TB patients and the production of interferon-gamma (IFN-gamma), indicating that endogenous levels of cortisol may contribute to the decreased lymphoid cell response to mycobacterium antigens observed in TB patients. DHEA did not affect lymphoid cell proliferation, IFN-gamma production and the cortisol-mediated inhibitory effects. Interestingly, we found that DHEA, but not cortisol, suppressed the in vitro transforming growth factor-beta production by lymphoid cells from TB patients with an advanced disease, which is indicative of a selective direct effect of this hormone.
Asunto(s)
Adyuvantes Inmunológicos/farmacología , Antiinflamatorios/farmacología , Antígenos Bacterianos/inmunología , Deshidroepiandrosterona/farmacología , Hidrocortisona/farmacología , Leucocitos Mononucleares/efectos de los fármacos , Tuberculosis/tratamiento farmacológico , Adulto , Anciano , División Celular/inmunología , Citocinas/metabolismo , Femenino , Humanos , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/metabolismo , Masculino , Persona de Mediana Edad , Mycobacterium tuberculosis/inmunología , Tuberculosis/inmunologíaRESUMEN
Inoculation at weaning with Trypanosoma cruzi in inbred "l" rats resulted in a self-resolving acute infection characterized by marked parasitaemias, whereas challenge to adult rats revealed a mild disease with extremely low parasitaemias. To explore the mechanisms underlying such age-associated differences in disease outcome, we analysed the in vitro replication of T. cruzi, nitric oxide and tumour necrosis factor-alpha (TNF-alpha) production in peritoneal macrophages (PMs), the serum concentrations of the specific immunoglobulins (Igs) IgM and IgG, antibodies exhibiting lytic activity against bloodstream forms of T. cruzi and circulating levels of nitrate, TNF-alpha and interferon-gamma (IFN-gamma). Macrophages from young rats were as effective as their adult counterparts for restraining intracellular parasite replication. When stimulated with IFN-gamma, culture supernatants from young PMs contained higher amounts of nitrite and TNF-alpha. Serum samples from 4 and 7 days post infection revealed easily detectable amounts of nitrate, with values being further augmented by day 7 post infection and significantly higher in the young group. TNF-alpha levels were only detected in the young group by day 7 post infection. Both groups had increased amounts of IFN-gamma in their sera, although in adult rats, this trend was followed by a significant drop at day 7, with young rats showing values still higher by the same time point evaluation. In contrast, young rats presented significantly lower levels of IgM and IgG antibodies during the first week of infection. Increased resistance in adult rats seems to be the result of a more appropriate antibody production.
Asunto(s)
Anticuerpos Antiprotozoarios/inmunología , Enfermedad de Chagas/inmunología , Trypanosoma cruzi/inmunología , Factores de Edad , Animales , Anticuerpos Antiprotozoarios/biosíntesis , Anticuerpos Antiprotozoarios/sangre , Enfermedad de Chagas/sangre , Enfermedad de Chagas/parasitología , Hemólisis/inmunología , Inmunidad Innata/inmunología , Interferón gamma/inmunología , Activación de Macrófagos/inmunología , Macrófagos Peritoneales/inmunología , Masculino , Óxido Nítrico/inmunología , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Parasitemia/inmunología , Parasitemia/parasitología , Ratas , Estadísticas no Paramétricas , Trypanosoma cruzi/crecimiento & desarrollo , Factor de Necrosis Tumoral alfa/inmunología , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Inoculation of Trypanosoma cruzi, Tulahuén strain, into C57BL/6 and BALB/c mice led to an acute infection characterized by marked parasitaemia, myocardial inflammation and thymocyte depletion. While C57BL/6 mice showed a progressive and lethal disease, BALB/c mice partly recovered. To characterize these murine models more effectively, we studied the parasite burden, serum levels of major infection outcome-related cytokines, the in vitro features of T. cruzi infection in peritoneal macrophages and the immunophenotype of thymic cells. The greater disease severity of T. cruzi-infected C57BL/6 mice was not linked to an increased parasite load, as parasitaemia, myocardial parasite nests and amastigote counts in peritoneal macrophages were not different from those in BALB/c mice. Cortical thymocyte loss was accompanied by the presence of apoptotic bodies and fragmented nuclear DNA, whereas fluorocytometric analysis at 17 days postinfection (p.i.) revealed a more pronounced loss of CD4+ CD8+ cells in C57BL/6 mice. This group displayed higher levels of TNF-alpha on days 14 and 21 p.i., in the presence of lower IL-1beta and IL-10 concentrations by days 14 and 21, and days 7 and 14 p.i., respectively. Day-21 evaluation showed higher concentrations of nitrate and TNF-alpha soluble receptors in C57BL/6 mice with no differences in IFN-gamma levels, with respect to the BALB/c group. Increased morbidity of C57BL/6 T. cruzi-infected mice does not seem to result from an aggravated infection but from an unbalanced relationship between pro- and anti-inflammatory mediators.