RESUMEN
We have reported previously that T cells from patients with multi-drug-resistant tuberculosis (MDR-TB) express high levels of interleukin (IL)-17 in response to the MDR strain M (Haarlem family) of Mycobacterium tuberculosis (M. tuberculosis). Herein, we explore the pathways involved in the induction of Th17 cells in MDR-TB patients and healthy tuberculin reactors [purified protein derivative healthy donors (PPD+ HD)] by the M strain and the laboratory strain H37Rv. Our results show that IL-1ß and IL-6 are crucial for the H37Rv and M-induced expansion of IL-17+ interferon (IFN)-γ- and IL-17+ IFN-γ+ in CD4+ T cells from MDR-TB and PPD+ HD. IL-23 plays an ambiguous role in T helper type 1 (Th1) and Th17 profiles: alone, IL-23 is responsible for M. tuberculosis-induced IL-17 and IFN-γ expression in CD4+ T cells from PPD+ HD whereas, together with transforming growth factor (TGF-ß), it promotes IL-17+ IFN-γ- expansion in MDR-TB. In fact, spontaneous and M. tuberculosis-induced TGF-ß secretion is increased in cells from MDR-TB, the M strain being the highest inducer. Interestingly, Toll-like receptor (TLR)-2 signalling mediates the expansion of IL-17+ IFN-γ- cells and the enhancement of latency-associated protein (LAP) expression in CD14+ and CD4+ T cells from MDR-TB, which suggests that the M strain promotes IL-17+ IFN-γ- T cells through a strong TLR-2-dependent TGF-ß production by antigen-presenting cells and CD4+ T cells. Finally, CD4+ T cells from MDR-TB patients infected with MDR Haarlem strains show higher IL-17+ IFN-γ- and lower IL-17+ IFN-γ+ levels than LAM-infected patients. The present findings deepen our understanding of the role of IL-17 in MDR-TB and highlight the influence of the genetic background of the infecting M. tuberculosis strain on the ex-vivo Th17 response.
Asunto(s)
Memoria Inmunológica , Interleucina-17/metabolismo , Interleucina-23/metabolismo , Mycobacterium tuberculosis/inmunología , Células Th17/inmunología , Factor de Crecimiento Transformador beta/metabolismo , Tuberculosis Resistente a Múltiples Medicamentos/inmunología , Tuberculosis Pulmonar/inmunología , Adulto , Células Cultivadas , Farmacorresistencia Bacteriana Múltiple , Femenino , Humanos , Interferón gamma/metabolismo , Masculino , Persona de Mediana Edad , Mycobacterium tuberculosis/genética , Transducción de Señal , Especificidad de la Especie , Células Th17/microbiología , Receptor Toll-Like 2/metabolismo , Tuberculosis Resistente a Múltiples Medicamentos/genética , Tuberculosis Pulmonar/microbiología , Adulto JovenRESUMEN
Interleukin 9 (IL-9) is a T-cell derived factor preferentially expressed by CD4+ Th2 cells and it has been characterized both in human and murine systems. It is a pleiotropic cytokine with multiple functions on cells of the lymphoid, myeloid and mast cell lineages, as well as on lung epithelial cells. Other activities described for IL-9 support its contribution to asthma and its important role in helminthic infections, where a Th2 response can be protective and IL-9 enhances resistance or is responsible for elimination of the nematode. Nevertheless, until recently there were no studies on its role in bacterial infections in man. We have demonstrated that cytokines can modulate the specific cytotoxicity generation in peripheral blood mononuclear cells from leprosy patients and normal controls. In the present report we studied the effect of IL-9 in this experimental model. Our results indicate that IL-9 can counteract the negative effect mediated by IL-4 on the generation of M. leprae-induced cytotoxic T lymphocytes. Moreover, it can increase this lytic activity in controls and enhance the stimulatory effect of IL-2 or IL-6 in cells from leprosy patients and controls. IL-9 is also able to revert the inhibitory effect of IL-10 and IL-13 on the M. leprae-induced cytotoxic activity. Although the exact mechanism of action of IL-9 remains to be determined, interferon gamma seems to be required for the effect of IL-9 in this experimental model. These data suggest that IL-9 may have an atypical Th2 behaviour and play a role in the modulation of the immune response to mycobacterial infections.
Asunto(s)
Interferón gamma/inmunología , Interleucina-9/farmacología , Lepra/inmunología , Mycobacterium leprae , Linfocitos T/inmunología , Adolescente , Adulto , Anciano , Estudios de Casos y Controles , Células Cultivadas , Citotoxicidad Inmunológica , Femenino , Humanos , Inmunización , Interferón gamma/genética , Interleucina-10/inmunología , Interleucina-13/inmunología , Interleucina-2/inmunología , Interleucina-4/inmunología , Interleucina-6/inmunología , Macrófagos/inmunología , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estadísticas no ParamétricasRESUMEN
Protection against intracellular pathogens such as Mycobacterium leprae is critically dependent on the function of NK cells at early stages of the immune response and on Th1 cells at later stages. In the present report we evaluated the role of IL-18 and IL-13, two cytokines that can influence NK cell activity, in the generation of M. leprae-derived hsp65-cytotoxic T lymphocytes (CTL) from peripheral blood mononuclear cells (PBMC) of leprosy patients. We demonstrated that IL-18 modulates hsp65-induced CTL generation and collaborates with IL-12 for this effect. In paucibacillary (PB) patients and normal controls (N) depletion of NK cells reduces the cytolytic activity. Under these conditions, IL-12 cannot up-regulate this CTL generation, while, in contrast, IL-18 increases the cytotoxic activity both in the presence or absence of NK cells. IL-13 down-regulates the hsp65-induced CTL generation and counteracts the positive effect of IL-18. The negative effect of IL-13 is observed in the early stages of the response, suggesting that this cytokine affects IFNgamma production by NK cells. mRNA coding for IFNgamma is induced by IL-18 and reduced in the presence of IL-13, when PBMC from N or PB patients are stimulated with hsp65. Neutralization of IL-13 in PBMC from multibacillary (MB) leprosy patients induces the production of IFNgamma protein by lymphocytes. A modulatory role on the generation of hsp65 induced CTL is demonstrated for IL-18 and IL-13 and this effect takes place through the production of IFNgamma.
Asunto(s)
Proteínas Bacterianas/inmunología , Chaperoninas/inmunología , Interleucina-13/inmunología , Interleucina-18/inmunología , Células Asesinas Naturales/inmunología , Lepra/inmunología , Adulto , Anciano , Antígeno CD56/análisis , Chaperonina 60 , Citotoxicidad Inmunológica/inmunología , Humanos , Interferón gamma/biosíntesis , Interferón gamma/genética , Interferón gamma/inmunología , Interleucina-12/inmunología , Persona de Mediana Edad , Mycobacterium leprae/inmunología , ARN Mensajero/genética , Linfocitos T Citotóxicos/inmunologíaRESUMEN
Peripheral blood mononuclear cells from leprosy patients and normal individuals were analysed for their ability to lyse autologous macrophages pulsed with the Mycobacterium leprae 10 kDa heat shock protein (hsp10), an antigen considered to have an important role in the protective responses in leprosy. Strong cytotoxic responses, with an involvement of gammadelta T and class-I and class-II restricted alphabeta T cells and/or CD16+56+ cells, were observed in normal individuals, paucibacillary (PB) and those multibacillary (MB) patients with undetectable bacillary load. On the contrary, only a weak class-II restricted cytotoxic response was observed in those MB patients with positive bacillary load (MB(+)). Simultaneous addition of IFNgamma plus TNFalpha and IL-12 during hsp10 stimulation could partially upregulate the low cytotoxic response observed in MB(+) by enhancing class-II restricted T cell activity and by development of gammadelta T and/or CD16+56+ cell activity. Our results suggest that the ability to mount an effective cytotoxic response against hsp10-pulsed macrophages in leprosy patients is closely related to the patient's bacterial load and not to the clinical form of the disease.