RESUMEN
Atopic diseases such as allergy and asthma are characterized by increases in Th2 cells and serum IgE antibodies. The binding of allergens to IgE on mast cells triggers the release of several mediators, of which histamine is the most prevalent. Here we show that histamine, together with a maturation signal, acts directly upon immature dendritic cells (iDCs), profoundly altering their T cell polarizing capacity. We demonstrate that iDCs express two active histamine receptors, H1 and H2. Histamine did not significantly affect the LPS-driven maturation of iDCs with regard to phenotypic changes or capacity to prime naive T cells, but it dramatically altered the repertoire of cytokines and chemokines secreted by mature DCs. In particular, histamine, acting upon the H2 receptor for a short period of time, increased IL-10 production and reduced IL-12 secretion. As a result, histamine-matured DCs polarized naive CD4(+) T cells toward a Th2 phenotype, as compared with DCs that had matured in the absence of histamine. We propose that the Th2 cells favor IgE production, leading to increased histamine secretion by mast cells, thus creating a positive feedback loop that could contribute to the severity of atopic diseases.
Asunto(s)
Citocinas/biosíntesis , Células Dendríticas/efectos de los fármacos , Proteínas de Drosophila , Histamina/farmacología , Linfocitos T/efectos de los fármacos , Polaridad Celular , Células Dendríticas/metabolismo , Humanos , Hipersensibilidad/etiología , Inmunoglobulina E/biosíntesis , Interleucina-10/fisiología , Interleucina-12/metabolismo , Lipopolisacáridos/farmacología , Glicoproteínas de Membrana/fisiología , Receptores de Superficie Celular/fisiología , Receptores Histamínicos/análisis , Receptores Histamínicos/fisiología , Linfocitos T/fisiología , Receptores Toll-LikeRESUMEN
A number of pathogens induce immature dendritic cells (iDC) to migrate to lymphoid organs where, as mature DC (mDC), they serve as efficient APC. We hypothesized that pathogen recognition by iDC is mediated by Toll-like receptors (TLRs), and asked which TLRs are expressed during the progression of monocytes to mDC. We first measured mRNA levels for TLRs 1-5 and MD2 (a protein required for TLR4 function) by Northern analysis. For most TLRs, message expression decreased severalfold as monocytes differentiated into iDC, but opposing this trend, TLR3 and MD2 showed marked increases during iDC formation. When iDC were induced to mature with LPS or TNF-alpha, expression of most TLRs transiently increased and then nearly disappeared. Stimulation of iDC, but not mDC, with LPS resulted in the activation of IL-1 receptor-associated kinase, an early component in the TLR signaling pathway, strongly suggesting that LPS signals through a TLR. Surface expression of TLRs 1 and 4, as measured by mAb binding, was very low, corresponding to a few thousand molecules per cell in monocytes, and a few hundred or less in iDC. We conclude that TLRs are expressed in iDC and are involved in responses to at least one pathogen-derived substance, LPS. If TLR4 is solely responsible for LPS signaling in humans, as it is in mice, then its extremely low surface expression implies that it is a very efficient signal transducer in iDC.
Asunto(s)
Células Dendríticas/metabolismo , Proteínas de Drosophila , Glicoproteínas de Membrana/biosíntesis , Monocitos/metabolismo , Receptores de Superficie Celular/biosíntesis , Antígenos de Superficie/biosíntesis , Northern Blotting , Diferenciación Celular/inmunología , Membrana Celular/inmunología , Membrana Celular/metabolismo , Células Cultivadas , Células Dendríticas/citología , Células Dendríticas/enzimología , Activación Enzimática/inmunología , Humanos , Quinasas Asociadas a Receptores de Interleucina-1 , Lipopolisacáridos/farmacología , Antígeno 96 de los Linfocitos , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/inmunología , Monocitos/citología , Monocitos/enzimología , Proteínas Quinasas/metabolismo , ARN Mensajero/biosíntesis , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/inmunología , Receptores de Interleucina-1/metabolismo , Receptor Toll-Like 3 , Receptor Toll-Like 4 , Receptores Toll-Like , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
BACKGROUND: Previous studies in our laboratory indicate that alcohol consumption suppresses the metastasis of B16BL6 melanoma, whereas the cytolytic activity of natural killer (NK) cells is decreased in female C57BL/6 mice given 20% w/v alcohol in their drinking water. In the present study, we further evaluated the involvement of NK cells and alcohol consumption in the cytolytic activity of NK cells, the surface expression of NK phenotypic markers, and metastasis of B16BL6 melanoma in C57BL/6 beige (bgJ/bgJ) mutant mice, which possess inherently low NK-cell cytolytic activity. METHODS: Beige and control (bgJ/+) mice were given either water or 20% w/v of alcohol in drinking water for 6 1/2 to 7 weeks before assay for cytolytic activity, surface marker expression, and inoculation with B16BL6 melanoma intravenously or into the pinna of the ear. RESULTS: NK cytolytic activity was suppressed in beige mice, and alcohol consumption did not modulate further the cytolytic activity. Beige mice had a lower percentage of NK cells in the peripheral blood and spleen than control mice. Peripheral blood lymphocytes from beige mice also exhibited a reduced percentage of CD4+ T lymphocytes. Alcohol consumption similarly reduced the percentages of NK1.1- and LGL-1-expressing lymphocytes in the peripheral blood and spleen and reduced the percentage of CD8+ T lymphocytes in the peripheral blood in both control and beige mice. Tumor lung colonization was increased in beige mice relative to control mice after intravenous inoculation of B16BL6 melanoma. The increase was more pronounced in water-drinking beige mice than in control mice irrespective of alcohol consumption. Tumor lung colonization was significantly decreased (p < 0.05) by alcohol consumption in one experiment and partially decreased (p = 0.07) in the other. Mice that were inoculated into the pinna of the ear also exhibited a blunted antimetastatic response to alcohol consumption. CONCLUSIONS: These data suggest that the presence of the beige mutation diminishes the antimetastatic effect of alcohol consumption and that there is no interaction between alcohol consumption and NK-cell activity in the modulation of lung metastasis of B16BL6 melanoma cells.
Asunto(s)
Consumo de Bebidas Alcohólicas/metabolismo , Células Asesinas Naturales/metabolismo , Neoplasias Pulmonares/secundario , Melanoma Experimental/secundario , Consumo de Bebidas Alcohólicas/genética , Animales , Depresores del Sistema Nervioso Central/farmacología , Etanol/farmacología , Femenino , Células Asesinas Naturales/efectos de los fármacos , Neoplasias Pulmonares/metabolismo , Melanoma Experimental/genética , Melanoma Experimental/metabolismo , Ratones , Ratones Endogámicos C57BL , Mutación/genéticaRESUMEN
Alcohol consumption in mice suppresses the cytolytic activity of natural killer (NK) and lymphokine-activated killer (LAK) cells through unknown mechanisms. Herein, we found that alcohol consumption decreased target cell-induced release of granzyme A activity in freshly isolated splenic NK cells, in NK cells stimulated for 18 h with 1000 IU/ml of interleukin 2, and in LAK cells. The total activity and protein expression of granzymes A and B also were lower in these cells than in cells isolated from water-drinking mice. Interleukin 2 increased granzyme A protein expression independent of alcohol consumption; however, this increase was associated with decreased enzyme activity. In contrast, granzyme B protein expression and enzymatic activity increased in response to interleukin 2. Perforin activity and protein expression were reduced in LAK cells generated from alcohol-consuming mice. We conclude that the mechanism underlying the suppression of NK and LAK cytolytic activity by alcohol consumption involves the collective reduction of target-induced release, activity, and expression of perforin and granular proteases.