RESUMEN
Paracoccidioidomycosis (PCM), is a pulmonary fungal disease whose severity depends on the adequate development of T cell immunity. Although regulatory T (Treg) cells were shown to control immunity against PCM, deleterious or protective effects were described in different experimental settings. To clarify the function of Treg cells in pulmonary PCM, loss-and gain-of-function approaches were performed with Foxp3GFP knock-in mice and immunodeficient Rag1-/- mice, respectively, which were intratracheally infected with 106 yeast cells. The activity of Foxp3-expressing Treg cells in pulmonary PCM was determined in Foxp3GFP transgenic mice. First, it was verified that natural Treg cells migrate to the lungs of infected mice, where they become activated. Depletion of Treg cells led to reduced fungal load, diminished pathogen dissemination and increased Th1/Th2/Th17 immunity. Further, adoptive transfer of diverse T cell subsets to Rag1-/- mice subsequently infected by the pulmonary route demonstrated that isolated CD4+Foxp3+ Treg cells were able to confer some degree of immunoprotection and that CD4+Foxp3- T cells alone reduced fungal growth and enhanced T cell immunity, but induced vigorous inflammatory reactions in the lungs. Nevertheless, transfer of Treg cells combined with CD4+Foxp3- T cells generated more efficient and balanced immune Th1/Th2/Th17 responses able to limit pathogen growth and excessive tissue inflammation, leading to regressive disease and increased survival rates. Altogether, these loss- and gain-of-function approaches allow us to clearly demonstrate the dual role of Treg cells in pulmonary PCM, their deleterious effects by impairing T cell immunity and pathogen eradication, and their protective role by suppressing exacerbated tissue inflammation.
Asunto(s)
Enfermedades Pulmonares Fúngicas/inmunología , Paracoccidioidomicosis/inmunología , Linfocitos T Reguladores/inmunología , Animales , Fusión Artificial Génica , Movimiento Celular , Factores de Transcripción Forkhead/genética , Proteínas Fluorescentes Verdes/análisis , Proteínas Fluorescentes Verdes/genética , Pulmón/inmunología , Pulmón/patología , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Coloración y Etiquetado/métodos , Subgrupos de Linfocitos T/inmunología , Linfocitos T Reguladores/químicaRESUMEN
Chagas disease is a Trypanosoma cruzi-induced zoonosis that has no natural cure. Local damage induced by the parasite and the immune response causes chronic heart and digestive lesions. Efforts to develop a therapeutic vaccine that boosts the immune response to completely clear the parasite are needed because there is no effective treatment for chronically infected patients. In an attempt to modify the host-parasite equilibrium to increase parasite destruction, we analyzed cardiopathy and the immune response in chronically infected mice that were challenged with live homologous parasites. Challenge with a single dose of parasite increased CD4(+) and CD8(+) T cell populations, gamma interferon (IFN-γ) production, and serum-specific IgG levels. However, subpatent parasitemias and cardiac tissue were not affected. Because of the short duration of the immune boost after a single challenge, we next evaluated the impact of four parasite doses, administered 3 weeks apart. At 1 to 2 months after the last dose, the numbers of CD4(+) T cells and IFN-γ-producing CD4(+) memory cells and the CD4(+) T cell proliferative response to T. cruzi antigen were increased in the spleen. The frequency of IFN-γ-producing CD8(+) memory cells in the blood was also increased. However, the sustained challenge did not favor TH1 development; rather, it induced an increase in serum-specific IgG1 levels and mixed TH1/TH2 cytokine production. Moreover, there were no significant changes in cardiac lesions and subpatent parasitemias. In conclusion, we believe that this study may help in elucidating the necessary elements for a successful therapeutic vaccine which may reduce cardiomyopathy in chronically infected human patients.
Asunto(s)
Enfermedad de Chagas/inmunología , Corazón/parasitología , Miocardio/patología , Vacunas Antiprotozoos/inmunología , Trypanosoma cruzi/inmunología , Animales , Anticuerpos Antiprotozoarios/sangre , Anticuerpos Antiprotozoarios/inmunología , Antígenos de Protozoos/inmunología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Enfermedad de Chagas/parasitología , Enfermedad de Chagas/prevención & control , Femenino , Interacciones Huésped-Parásitos/inmunología , Inmunoglobulina G/sangre , Interferón gamma/inmunología , Activación de Linfocitos/inmunología , Masculino , Ratones , Ratones Endogámicos C3HRESUMEN
Plasmodium chabaudi infection induces a rapid and intense splenic CD4(+) T cell response that contributes to both disease pathogenesis and the control of acute parasitemia. The subsequent development of clinical immunity to disease occurs concomitantly with the persistence of low levels of chronic parasitemia. The suppressive activity of regulatory T (T(reg)) cells has been implicated in both development of clinical immunity and parasite persistence. To evaluate whether IL-2 is required to induce and to sustain the suppressive activity of T(reg) cells in malaria, we examined in detail the effects of anti-IL-2 treatment with JES6-1 monoclonal antibody (mAb) on the splenic CD4(+) T cell response during acute and chronic P. chabaudi AS infection in C57BL/6 mice. JES6-1 treatment on days 0, 2 and 4 of infection partially inhibits the expansion of the CD4(+)CD25(+)Foxp3(+) cell population during acute malaria. Despite the concomitant secretion of IL-2 and expression of high affinity IL-2 receptor by large CD4(+) T cells, JES6-1 treatment does not impair effector CD4(+) T cell activation and IFN-γ production. However, at the chronic phase of the disease, an enhancement of cellular and humoral responses occurs in JES6-1-treated mice, with increased production of TNF-α and parasite-specific IgG2a antibodies. Furthermore, JES6-1 mAb completely blocked the in vitro proliferation of CD4(+) T cells from non-treated chronic mice, while it further increased the response of CD4(+) T cells from JES6-1-treated chronic mice. We conclude that JES6-1 treatment impairs the expansion of T(reg) cell population during early P. chabaudi malaria and enhances the Th1 cell response in the late phase of the disease.
Asunto(s)
Anticuerpos Monoclonales/inmunología , Interleucina-2/inmunología , Malaria/inmunología , Linfocitos T Reguladores/inmunología , Células TH1/inmunología , Animales , Anticuerpos Monoclonales/farmacología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Enfermedad Crónica , Femenino , Citometría de Flujo , Factores de Transcripción Forkhead/inmunología , Factores de Transcripción Forkhead/metabolismo , Inmunofenotipificación , Interferón gamma/inmunología , Interferón gamma/metabolismo , Interleucina-2/metabolismo , Subunidad alfa del Receptor de Interleucina-2/inmunología , Subunidad alfa del Receptor de Interleucina-2/metabolismo , Subunidad beta del Receptor de Interleucina-2/inmunología , Subunidad beta del Receptor de Interleucina-2/metabolismo , Activación de Linfocitos/efectos de los fármacos , Activación de Linfocitos/inmunología , Malaria/tratamiento farmacológico , Malaria/parasitología , Ratones , Ratones Endogámicos C57BL , Parasitemia/tratamiento farmacológico , Parasitemia/inmunología , Parasitemia/parasitología , Plasmodium chabaudi/efectos de los fármacos , Plasmodium chabaudi/inmunología , Bazo/citología , Bazo/inmunología , Bazo/metabolismo , Linfocitos T Reguladores/metabolismo , Células TH1/metabolismoRESUMEN
Loxosceles adelaida spiders (Araneae, Sicariidae) are found near and inside the caves in the Parque Estadual Turistico do Alto Ribeira (PETAR), Sao Paulo, Brazil, which are visited by thousands of tourists every year. Several Loxosceles species are a public health problem in many regions of the world, by causing severe dermonecrosis and/or complement dependent haemolysis upon envenomation. The aim of this study was to characterize the biochemical and biological properties of L. adelaida venom and evaluate the toxic potential of envenomation by this non-synanthropic Loxosceles species. The biological activities of the L. adelaida venom was compared to that of Loxosceles gaucho, a synanthropic species of medical importance in Brazil. L. adelaida venom showed a similar potential to induce haemolysis, dermonecrosis and lethality as L. gaucho venom. L. adelaida crude venom was purified, yielding a 31 kDa component endowed with haemolytic and dermonecrotic activities. In conclusion, we show here that the troglophile Loxosceles species, L. adelaida, commonly found in the complex of caves from PETAR, is potentially able to cause envenomation with the same gravity of those produced by synanthropic species.
Asunto(s)
Hemólisis/efectos de los fármacos , Piel/patología , Esfingomielina Fosfodiesterasa/toxicidad , Venenos de Araña/química , Arañas/química , Animales , Western Blotting , Brasil , Cromatografía Líquida de Alta Presión , Electroforesis en Gel Bidimensional , Ensayo de Inmunoadsorción Enzimática , Eritrocitos/efectos de los fármacos , Citometría de Flujo , Dosificación Letal Mediana , Ratones , Necrosis/inducido químicamente , Conejos , Especificidad de la Especie , Esfingomielina Fosfodiesterasa/aislamiento & purificación , Venenos de Araña/enzimología , Arañas/enzimologíaRESUMEN
Loxosceles adelaida spiders (Araneae, Sicariidae) are found near and inside the caves in the Parque Estadual Turístico do Alto Ribeira (PETAR), São Paulo, Brazil, which are visited by thousands of tourists every year. Several Loxosceles species are a public health problem in many regions of the world, by causing severe dermonecrosis and/or complement dependent haemolysis upon envenomation. The aim of this study was to characterize the biochemical and biological properties of L. adelaida venom and evaluate the toxic potential of envenomation by this non-synanthropic Loxosceles species. The biological activities of the L. adelaida venom was compared to that of Loxosceles gaucho, a synanthropic species of medical importance in Brazil. L. adelaida venom showed a similar potential to induce haemolysis, dermonecrosis and lethality as L. gaucho venom. L. adelaida crude venom was purified, yielding a 31 kDa component endowed with haemolytic and dermonecrotic activities. In conclusion, we show here that the troglophile Loxosceles species, L. adelaida, commonly found in the complex of caves from PETAR, is potentially able to cause envenomation with the same gravity of those produced by synanthropic species.