RESUMEN
The prevalence of asthma and allergies often observed in urban metropolitan areas as compared to rural and farm communities is still an enigma. Westernized life styles, type of farming and exposure to environmental pollutants seem to simultaneously interact in the determination of this phenotype in genetically predisposed individuals. In this scenario, we asked whether and to what extent we could single out antropogenic airborne contaminants in general, and platinum group elements in particular as relevant causal factors in the generation and in the clinical expression of allergic immune responses in exposed individuals. To this aim, we evaluated epidemiological and basic immunology studies published on peer-reviewed journals indexed in Medline on this subject. We reviewed studies focused on effect of the exposure to platinum group elements on the allergic immune response, with specific reference to our own studies, on their influence on dendritic cells and on the consequent skewing of T-helper and T-regulatory lymphocyte functions. Our laboratory contributed to generate consistent evidence supporting the notion that anthropogenic emissions in general, and platinum group elements in particular, can functionally modulate the immune response in a coordinated pro-allergic fashion. We conclude that in genetically predisposed individuals platinum group elements exert an adjuvant effect specifically leading to more severe allergic reactions.
Asunto(s)
Adyuvantes Inmunológicos/efectos adversos , Contaminantes Atmosféricos/efectos adversos , Asma/epidemiología , Asma/inmunología , Exposición a Riesgos Ambientales/efectos adversos , Platino (Metal)/efectos adversos , Animales , Asma/inducido químicamente , Células Dendríticas/inmunología , Predisposición Genética a la Enfermedad/epidemiología , Humanos , Linfocitos T Reguladores/inmunología , Salud UrbanaRESUMEN
Sublingual immunotherapy is safe and efficacious in the treatment of patients with allergic rhinitis. The clinical and biological efficacy of modified allergens (allergoids) has not been fully clarified. We investigated in birch allergic patients the effect of a pre-co-seasonal sublingual immunotherapy regimen with a modified allergen extract on clinical parameters and on T cell proliferation and regulatory cytokine production (IL-10, TGF-beta). We found that during the birch pollen season symptoms and drug usage scores were 30 and 40 percent improved, respectively, in treated versus control subjects (p<0.0001 for both comparisons) whereas well days were 23.5 (33 percent) versus 16.9 (23 percent) (p=0.0024), respectively. Bet v 1 allergen specific proliferation decreased (p = 0.0010), whereas IL-10 transcription increased (p=0.0010) in treated, but not in control patients. Moreover, TGF-beta transcription was increased, although not significantly (p=0.066), following immunotherapy. Thus, sublingual immunotherapy with modified allergen in birch-allergic subjects was safe, clinically efficacious and associated with the reduction of allergen-specific proliferation and with the increased production of the IL-10 regulatory cytokine.
Asunto(s)
Antígenos de Plantas/administración & dosificación , Betula/inmunología , Conjuntivitis Alérgica/prevención & control , Desensibilización Inmunológica , Extractos Vegetales/administración & dosificación , Polen/inmunología , Rinitis Alérgica Estacional/prevención & control , Administración Sublingual , Adolescente , Adulto , Alergoides , Antialérgicos/uso terapéutico , Antígenos de Plantas/inmunología , Proliferación Celular , Células Cultivadas , Conjuntivitis Alérgica/inmunología , Femenino , Humanos , Interleucina-10/genética , Activación de Linfocitos , Masculino , Persona de Mediana Edad , Proyectos Piloto , Extractos Vegetales/inmunología , Rinitis Alérgica Estacional/inmunología , Linfocitos T/inmunología , Transcripción Genética , Factor de Crecimiento Transformador beta/genética , Resultado del Tratamiento , Adulto JovenRESUMEN
Immature dendritic cells (DCs) modulate differentiation markers following in vitro exposure to chemicals generating contact allergies. THP-1 is a monocytoid cell line maintaining some differentiating plasticity. In this study, human DCs and THP-1 cells were compared as in vitro models to predict contact sensitisation of chemicals with different sensitising potential. Expression of CD80 and CD86 was assessed by flow cytometry after exposure to subtoxic concentrations of potent (2,4-dinitrochlorobenzene, DNCB and p-phenylendiamine, PPD), strong (thimerosal, TMS), moderate (sodium tetrachloroplatinate, Na2PtCl4) sensitising compounds as well as of non-sensitising, irritating sodium dodecyl sulphate (SDS) as compared to a vehicle of sensitising substances (dimethyl sulphoxide, DMSO). Up-regulation of CD86 following in vitro incubation of DCs and THP-1 cells with DNCB, PPD, TMS and Na2PtCl4, but not with SDS, was observed. The CD80 membrane marker was up-regulated on DCs following in vitro incubation with DNCB and PPD, but not with TMS, Na2PtCl4. and SDS. On THP-1 cells, only DNCB up-regulated CD80 expression. In conclusion, both the cell line THP-1 and DCs are promising in vitro models for assays aiming at predicting the sensitisation potential of chemicals. THP-1 cell line is by far easier to handle and offers relevant advantages from the practical point of view.
Asunto(s)
Células Dendríticas/citología , Dermatitis por Contacto/inmunología , Relación Dosis-Respuesta a Droga , Modelos Biológicos , Monocitos/citología , Sensibilidad Química Múltiple/patología , Línea Celular , Línea Celular Tumoral , Células Cultivadas , Dermatitis por Contacto/patología , Humanos , Sensibilidad Química Múltiple/inmunologíaRESUMEN
Chromium compounds, besides being occupational carcinogens, can also induce allergic contact dermatitis (ACD) and other immunomodulatory effects. In this study we investigate cell viability, uptake and intracellular distribution of chromium in human primary dendritic cells (DCs), either immature (iDCs) or driven to differentiate by a specific maturation stimulus (LPS) (mature DCs, mDCs), when exposed for 48 h to concentrations of soluble radiolabelled Na251CrO4 ranging from 5 to 0.5 microM. The modulation of the expression of membrane markers (CD80, CD86, MHC class II) correlated with the immunological functions of DCs was also measured. After 48 h of exposure the mean IC50 values in 4 donors were 36 and 31 microM in iDCs and mDC respectively, as detected by propidium iodide incorporation. Cellular uptake of chromium was nearly linear with increasing doses. At 48 h post-exposure chromium was accumulated preferentially in the nuclear and cytosolic fractions (44.1 to 66% and 13.1 to 31% of total cellular chromium, respectively). Although a high inter-individual variability was observed, an increase in the expression of CD86 and, to a lower extent, CD80 and MHC class II membrane markers was found in mDCs of single donors. These results highlight the relevance of searching for the biodistribution of trace metals in primary cells of the immune system. Moreover, they suggest that DCs differentiation markers can help in measuring the immunotoxicity of metal compounds with sensitisation potential.
Asunto(s)
Cromo/toxicidad , Células Dendríticas/efectos de los fármacos , Antígeno B7-1/análisis , Antígeno B7-2/análisis , Cromo/farmacocinética , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Relación Dosis-Respuesta a Droga , Antígenos de Histocompatibilidad Clase II/análisis , HumanosRESUMEN
The Bühlmann CAST 2000 enzyme-linked immunosorbent assay is a potentially useful assay for measuring sulfidoleukotrienes released in vitro by allergen-challenged basophils. However, we observed that the positive-control reagent yielded positive signals in cell-free systems. These false-positive results depended on using a mouse anti-FcepsilonRI monoclonal antibody and were prevented by degranulation-inducing reagents other than mouse monoclonal antibodies.
Asunto(s)
Basófilos/metabolismo , Degranulación de la Célula , Ensayo de Inmunoadsorción Enzimática , Leucotrienos/metabolismo , Juego de Reactivos para Diagnóstico , Animales , Anticuerpos Monoclonales , Degranulación de la Célula/inmunología , Células Cultivadas , Ensayo de Inmunoadsorción Enzimática/métodos , Ensayo de Inmunoadsorción Enzimática/normas , Reacciones Falso Positivas , Humanos , Ratones , Juego de Reactivos para Diagnóstico/normas , Reproducibilidad de los ResultadosRESUMEN
Unconventional immune responses have been demonstrated in individuals who, despite repeated exposure to human immunodeficiency virus (HIV) infection, remain seronegative. As environmental exposure to pathogens and genetic background may modulate immune responses differentially, one Italian and two Asian populations of HIV-1-exposed seronegative individuals were studied. In serum samples from each group, IgG to CCR5, IgG to CD4 and IgA to gp41 were measured, which were previously described as markers of unconventional immunity in HIV-exposed seronegative Caucasians. Given the importance of conformational epitopes in virus-cell interactions, IgG to CD4-gp120 complex was also measured. It was found that markers of HIV exposure were present in all populations studied. HIV-specific humoral responses (IgA to gp41 and IgG to CD4-gp120 complex) were extremely significant predictors of HIV exposure (P<0.0001 in both cases), whereas the predictive values of anti-cell antibodies (anti-CCR5 and anti-CD4) varied between populations. Evidence is provided for the correlation of these differences with route of exposure to HIV and level of natural antibodies to cross-reactive microbial antigens. In conclusion, exposed seronegative individuals of ethnically different origins display similar signs of HIV-dependent unconventional immunity. A specific relevance must be attributed to different innate and acquired factors.
Asunto(s)
Pueblo Asiatico , Seronegatividad para VIH/inmunología , VIH-1 , Población Blanca , Adolescente , Adulto , Especificidad de Anticuerpos , Antígenos CD4/inmunología , Linfocitos T CD4-Positivos/inmunología , Estudios de Cohortes , Femenino , Anticuerpos Anti-VIH/sangre , Proteína gp120 de Envoltorio del VIH/inmunología , Proteína gp41 de Envoltorio del VIH/inmunología , Seronegatividad para VIH/genética , Humanos , Inmunoglobulina A/sangre , Inmunoglobulina G/sangre , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Receptores CCR5/inmunologíaRESUMEN
The synthesis of the sugar-derived (1S,2R,8aR)-1,2-di-O-isopropylidene-1,2,3,5,6,8a-hexahydro-5-oxoindolizine (8) and by analogy of the corresponding stereoisomers ent-8 and ent-7, an epimer at C2 of ent-8, has been accomplished in a straightforward manner. The carbon-carbon double bond and the carbonyl functionalities on the six-membered ring make these nitrogen-containing heterocycles useful building blocks for the efficient preparation of a variety of enantiopure polyhydroxylated indolizidines of interest for their glycosidase inhibitory activity. We report here the synthesis of 2,8a-diepilentiginosine 12 from 8 and the preparation of stereoisomeric 1,2,7,8-tetrahydroxyindolizidines 9-11 performed by OsO4-catalyzed double bond syn dihydroxylation of 7 and 8, followed by deoxygenation of the amide group.
Asunto(s)
Indolizinas/síntesis química , Inhibidores Enzimáticos/síntesis química , Glicósido Hidrolasas/antagonistas & inhibidores , EstereoisomerismoRESUMEN
Salicylates inhibit T cell adhesion to and transmigration through endothelium by preventing integrin activation induced by contact with endothelial cells. In the present study the effects of aspirin and sodium salicylate on the first steps of T cell adhesion have been analyzed in a nonstatic in vitro system. Salicylates partially reduced adhesion to activated endothelium and, in parallel, L-selectin expression on resting T cells by inducing shedding of the molecule without affecting its mRNA transcript. The role of L-selectin down-regulation in reducing T cell adhesion in this system was supported by the fact that aspirin inhibited T cell adhesion also on plastic-immobilized L-selectin ligand or when alpha(4) integrin-mediated adhesion to endothelium was blocked by specific mAbs. In addition, preincubation of T cells with inhibitors of L-selectin shedding prevented both functional and phenotypic inhibitory effects of salicylates. The decrease in T cell adhesion and L-selectin expression seems to be dependent on intracellular calcium increase and tyrosine kinase activation, because these effects could be reversed by preincubating salicylate-treated T cells with EGTA, genistein, or tyrphostin. Finally, the infusion of aspirin into healthy volunteers induced down-regulation of L-selectin on circulating T cells. These results suggest that salicylates interfere not only with integrin activation, but also with the L-selectin-mediated first steps of T cell binding to endothelium.
Asunto(s)
Aspirina/farmacología , Movimiento Celular/efectos de los fármacos , Endotelio Vascular/inmunología , Endotelio Vascular/metabolismo , Inmunosupresores/farmacología , Selectina L/metabolismo , Proteínas Tirosina Quinasas/fisiología , Linfocitos T/efectos de los fármacos , Aspirina/administración & dosificación , Adhesión Celular/efectos de los fármacos , Adhesión Celular/inmunología , Movimiento Celular/inmunología , Sistema Libre de Células/inmunología , Sistema Libre de Células/metabolismo , Células Cultivadas , Dipéptidos/farmacología , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/inmunología , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Gangliósidos/metabolismo , Humanos , Ácidos Hidroxámicos/farmacología , Inmunosupresores/administración & dosificación , Inyecciones Intravenosas , Líquido Intracelular/efectos de los fármacos , Líquido Intracelular/inmunología , Células Jurkat , Selectina L/biosíntesis , Selectina L/genética , Antígenos del Grupo Sanguíneo de Lewis/metabolismo , Metaloendopeptidasas/antagonistas & inhibidores , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Inhibidores de Proteasas/farmacología , ARN Mensajero/biosíntesis , Antígeno Sialil Lewis X , Transducción de Señal/efectos de los fármacos , Transducción de Señal/inmunología , Salicilato de Sodio/farmacología , Linfocitos T/enzimología , Linfocitos T/metabolismo , Linfocitos T/fisiologíaRESUMEN
Tumor necrosis factor-alpha (TNFalpha)-induced maturation of dendritic cells (DC), with down-regulation of their endocytic ability, has been reported to be mediated by the accumulation of the lipid messenger ceramide. We have now studied the effects and mechanisms of action of NO on endocytosis, investigated with fluorescein isothiocyanate-labeled dextran using human monocyte-derived DC, both immature and after treatment with TNFalpha. Exposure of DC to NO, released by either bystander phagocytes or NO donors, reversed the inhibition of endocytosis induced by TNFalpha. The intracellular accumulation of ceramide induced by TNFalpha was also inhibited by NO. In addition, NO was found to exert an inhibitory effect downstream of the TNFalpha-triggered ceramide accumulation, because NO donors reversed the inhibition of endocytosis induced by the cell-permeant C(2)-ceramide. These effects of NO were mimicked by the membrane-permeant cyclic GMP analogue, 8-Br cyclic GMP, and prevented by inhibition of the soluble guanylyl cyclase. At variance with rodents, the inducible isoform of the NO synthase was expressed neither in immature human DC nor after cell treatment with TNFalpha, interferon-gamma, and lipopolysaccharide, suggesting that regulation of these cells depends on exogenous NO. NO, working through cyclic GMP, might therefore prolong the ability of human DC to internalize antigens at the site of inflammation and thus modulate the initial steps leading to antigen-specific immune responses.
Asunto(s)
GMP Cíclico/metabolismo , Células Dendríticas/metabolismo , Endocitosis/fisiología , Óxido Nítrico/farmacología , Factor de Necrosis Tumoral alfa/metabolismo , Animales , Western Blotting , Encéfalo/metabolismo , Células Cultivadas , Ceramidas/farmacocinética , Técnicas de Cocultivo , Regulación hacia Abajo , Inhibidores Enzimáticos/farmacocinética , Citometría de Flujo , Factor Estimulante de Colonias de Granulocitos y Macrófagos/farmacología , Humanos , Interleucina-4/farmacología , Leucocitos Mononucleares/metabolismo , Lipopolisacáridos/metabolismo , Ratones , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa de Tipo II , Esfingosina/análogos & derivados , Esfingosina/farmacocinética , Factores de Tiempo , Factor de Necrosis Tumoral alfa/antagonistas & inhibidoresRESUMEN
Gamma delta T cells are early recruited into mycobacterial lesions. Upon microbial Ag recognition, gamma delta cells secrete cytokines and chemokines and undergo apoptosis via CD95/CD95 ligand (CD95L) interaction, possibly influencing the outcome of infection and the characteristics of the disease. In this paper we show that activated phagocytes acquire, upon challenge with Mycobacterium tuberculosis, the ability to inhibit M. tuberculosis-induced gamma delta cell apoptosis. Apoptosis protection was due to NO because it correlated with NO synthase (NOS)-2 induction and activity in scavenger cells and was abrogated by NOS inhibitors. Furthermore, the NO donor S-nitrosoacetylpenicillamine mimicked the effect of enzyme induction. NO left unaffected the expression of CD95 and CD95L, suggesting interference with an event ensuing CD95/CD95L interaction. NO was found to interfere with the intracellular accumulation of ceramide and the activation of caspases, which were involved in gamma delta T cells apoptosis after M. tuberculosis recognition. We propose that NO generated by infected macrophages determines the life span and therefore the function of lymphocytes at the infection site, thus linking innate and adaptive immunity.
Asunto(s)
Apoptosis/inmunología , Mycobacterium tuberculosis/inmunología , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico/biosíntesis , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Animales , Antígenos Bacterianos/inmunología , Células Clonales , Regulación hacia Abajo/inmunología , Proteína Ligando Fas , Humanos , Inmunidad Innata , Líquido Intracelular/inmunología , Ligandos , Activación de Linfocitos/efectos de los fármacos , Activación de Macrófagos/inmunología , Glicoproteínas de Membrana/biosíntesis , Ratones , Microglía , Óxido Nítrico/farmacología , Óxido Nítrico/fisiología , Óxido Nítrico Sintasa de Tipo II , Fagocitos/inmunología , Transducción de Señal/inmunología , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/microbiología , Receptor fas/biosíntesis , Receptor fas/fisiologíaRESUMEN
SK-N-BE neuroblastoma cell clones transfected with p75(NTR) and lacking Trk neurotrophin receptors, previously reported to undergo extensive spontaneous apoptosis and to be protected by nerve growth factor (NGF) (Bunone, G., Mariotti, A., Compagni, A., Morandi, E., and Della Valle, G. (1997) Oncogene 14, 1463-1470), are shown to exhibit (i) increased levels of the pro-apoptotic lipid metabolite ceramide and (ii) high activity of caspases, the proteases of the cell death cascade. In the p75(NTR)-expressing cells, these parameters were partially normalized by prolonged NGF treatment, which, in addition, decreased apoptosis, similar to caspase blockers. Conversely, exogenous ceramide increased caspase activity and apoptosis in both wild-type and p75(NTR)-expressing cells. A new p75(NTR)-expressing clone characterized by low spontaneous apoptosis exhibited high endogenous ceramide and low caspase levels. A marked difference between the apoptotic and resistant clones concerned the very low and high activities of nitric-oxide (NO) synthase, respectively. Protection from apoptosis by NO was confirmed by results with the NO donor S-nitrosoacetylpenicillamine and the NO-trapping agent hemoglobin. We conclude that the p75(NTR) receptor, while free of NGF, triggers a cascade leading to apoptosis; the cascade includes generation of ceramide and increased caspase activity; and the protective role of NO occurs at step(s) in between the latter events.
Asunto(s)
Apoptosis/genética , Caspasas/metabolismo , Ceramidas/metabolismo , Óxido Nítrico/farmacología , Receptores de Factor de Crecimiento Nervioso/genética , Inhibidores de Caspasas , Inhibidores Enzimáticos/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Factores de Crecimiento Nervioso/farmacología , Neuroblastoma , Óxido Nítrico Sintasa/metabolismo , Penicilamina/análogos & derivados , Penicilamina/farmacología , Receptor de Factor de Crecimiento Nervioso , S-Nitroso-N-Acetilpenicilamina , Transducción de Señal/efectos de los fármacos , Células Tumorales CultivadasRESUMEN
The inhibition of cyclooxygenase does not fully account for the spectrum of activities of nonsteroidal antiinflammatory drugs. It is evident, indeed, that regulation of inflammatory cell function may contribute in explaining some of the effects of these drugs. Tissue recruitment of T cells plays a key role in the development of chronic inflammation. Therefore, the effects of salicylates on T-cell adhesion to and migration through endothelial cell monolayers on collagen were analyzed in an in vitro static system. Aspirin and sodium salicylate reduced the ability of unstimulated T cells to adhere to and transmigrate through cytokine-activated endothelium. Although salicylates did not modify the expression of integrins on T cells, they blunted the increased adherence induced by the anti-beta2 monoclonal antibody (MoAb) KIM127 and prevented the appearance of an activation-dependent epitope of the CD11/CD18 complex, recognized by the MoAb 24, induced by contact with endothelial cells. Salicylates also induced an increase of intracellular calcium ([Ca2+]i) and activation of protein kinase C (PKC) in T cells, but not cell proliferation and interleukin (IL)-2 synthesis. The reduction of T-cell adhesiveness appears to be dependent on the increase in[Ca2+]i levels, as it could be reversed by blocking Ca2+ influx, but not by inhibiting PKC. Moreover, ionomycin at concentrations giving an increase in [Ca2+]i similar to that triggered by aspirin, strictly reproduced the T-cell phenotypic and functional changes induced by salicylates. Aspirin reduced T-cell adhesion and migration also ex vivo after infusion to healthy volunteers. These data suggest that the antiinflammatory activity of salicylates may be due, at least in part, to an interference with the integrin-mediated binding of resting T lymphocytes to activated endothelium with consequent reduction of a specific T-cell recruitment into inflammatory sites.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Aspirina/farmacología , Quimiotaxis de Leucocito/efectos de los fármacos , Inhibidores de la Ciclooxigenasa/farmacología , Endotelio Vascular/fisiología , Integrina beta1/metabolismo , Salicilato de Sodio/farmacología , Linfocitos T/efectos de los fármacos , Antígenos CD11/metabolismo , Antígenos CD18/metabolismo , Calcio/metabolismo , Adhesión Celular/efectos de los fármacos , División Celular , Células Cultivadas , Colágeno , Citocinas/farmacología , Depresión Química , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Humanos , Interleucina-2/metabolismo , Transporte Iónico , Ionomicina/farmacología , Ionóforos/farmacología , Sustancias Macromoleculares , Linfocitos T/citología , Linfocitos T/metabolismo , Venas UmbilicalesRESUMEN
Vgamma9/Vdelta2+ T cells specifically recognize Mycobacterium tuberculosis in vitro and are precociously recruited in early mycobacterial lesions. Even if gammadelta T cells are only fortuitously detected in granulomas or bronchoalveolar lavages of patients with active pulmonary tuberculosis, a role in shaping the mature alphabeta T cell response against M. tuberculosis is substantiated. Here we provide a molecular explanation for this paradox: the engagement of the gammadelta TCR by mycobacterial antigens induced the expression of CD95 ligand (CD95L) by chronically activated CD95+/CD95L- gammadelta T lymphocytes. The receptor was functional, as CD95/CD95L interaction triggered the bystander death of CD95+ cells by apoptosis. Cell death was abolished by CD95-blocking antibodies. The transient accumulation at the site of infection of CD95L+ gammadelta lymphocytes, capable of interacting with CD95+ leukocytes attracted by the response towards the pathogen, may determine the characteristics of the ensuing granulomatous disease.