RESUMO
Chronic inflammation of the intestinal mucosa is characteristic of inflammatory bowel diseases such as ulcerative colitis and Crohn's disease. Helminth parasites have developed immunomodulatory strategies that may impact the outcome of several inflammatory diseases. Therefore, we investigated whether Taenia crassiceps infection is able to decrease the inflammatory effects of dextran sulfate sodium- (DSS-) induced ulcerative colitis in BALB/c and C57BL/6 mice. Preinfection significantly reduced the manifestations of DSS-induced colitis, as weight loss and shortened colon length, and decreased the disease activity index independently of the genetic background of the mice. Taenia infection decreased systemic levels of proinflammatory cytokines while increasing levels of IL-4 and IL-10, and the inflammatory infiltrate into the colon was also markedly reduced. RT-PCR assays from colon showed that T. crassiceps-infected mice displayed increased expression of Arginase-1 but decreased expression of iNOS compared to DSS-treated uninfected mice. The percentages of T regulatory cells were not increased. The adoptive transfer of alternatively activated macrophages (AAMФs) from infected mice into mice with DSS-induced colitis reduced the severity of colon inflammation. Administration of indomethacin abrogated the anticolitic effect of Taenia. Thus, T. crassiceps infection limits the pathology of ulcerative colitis by suppressing inflammatory responses mechanistically associated with AAMФs and prostaglandins.
Assuntos
Colite Ulcerativa/parasitologia , Doença de Crohn/parasitologia , Inflamação/parasitologia , Prostaglandinas/biossíntese , Animais , Arginase , Colite Ulcerativa/induzido quimicamente , Colite Ulcerativa/genética , Doença de Crohn/induzido quimicamente , Doença de Crohn/genética , Sulfato de Dextrana/toxicidade , Modelos Animais de Doenças , Feminino , Humanos , Inflamação/induzido quimicamente , Inflamação/genética , Interleucina-10/biossíntese , Interleucina-4/biossíntese , Mucosa Intestinal/parasitologia , Mucosa Intestinal/patologia , Macrófagos/metabolismo , Macrófagos/patologia , Camundongos , Óxido Nítrico Sintase Tipo II/biossíntese , Prostaglandinas/metabolismo , Taenia/patogenicidade , Teníase/complicações , Teníase/parasitologiaRESUMO
Three phenylpropanoid dimers (1-3) including two new metabolites were isolated from the extract of the twigs of Nectandra leucantha using antileishmanial bioassay-guided fractionation. The in vitro antiparasitic activity of the isolated compounds against Leishmania donovani parasites and mammalian cytotoxicity and immunomodulatory effects were evaluated. Compounds 1-3 were effective against the intracellular amastigotes within macrophages, with IC50 values of 26.7, 17.8, and 101.9 µM, respectively. The mammalian cytotoxicity, given by the 50% cytotoxic concentration (CC50), was evaluated against peritoneal macrophages. Compounds 1 and 3 were not toxic up to 290 µM, whereas compound 2 demonstrated a CC50 value of 111.2 µM. Compounds 1-3 also suppressed production of disease exacerbatory cytokines IL-6 and IL-10 but had minimal effect on nitric oxide production in L. donovani-infected macrophages, indicating that antileishmanial activity of these compounds is mediated via an NO-independent mechanism. Therefore, these new natural products could represent promising scaffolds for drug design studies for leishmaniasis.
Assuntos
Anisóis/isolamento & purificação , Anisóis/farmacologia , Antiprotozoários/isolamento & purificação , Antiprotozoários/farmacologia , Fatores Imunológicos/isolamento & purificação , Fatores Imunológicos/farmacologia , Lauraceae/química , Leishmaniose/tratamento farmacológico , Fenilpropionatos/isolamento & purificação , Fenilpropionatos/farmacologia , Animais , Anisóis/química , Antiprotozoários/química , Brasil , Fatores Imunológicos/química , Concentração Inibidora 50 , Interleucina-10 , Interleucina-6 , Leishmania donovani/efeitos dos fármacos , Macrófagos Peritoneais/efeitos dos fármacos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Estrutura Molecular , Óxido Nítrico/metabolismo , Fenilpropionatos/química , Caules de Planta/químicaRESUMO
C-type lectins are multifunctional sugar-binding molecules expressed on dendritic cells (DCs) and macrophages that internalize antigens for processing and presentation. Macrophage galactose-type lectin 1 (MGL1) recognizes glycoconjugates expressing Lewis X structures which contain galactose residues, and it is selectively expressed on immature DCs and macrophages. Helminth parasites contain large amounts of glycosylated components, which play a role in the immune regulation induced by such infections. Macrophages from MGL1(-/-) mice showed less binding ability toward parasite antigens than their wild-type (WT) counterparts. Exposure of WT macrophages to T. crassiceps antigens triggered tyrosine phosphorylation signaling activity, which was diminished in MGL1(-/-) macrophages. Following T. crassiceps infection, MGL1(-/-) mice failed to produce significant levels of inflammatory cytokines early in the infection compared to WT mice. In contrast, MGL1(-/-) mice developed a Th2-dominant immune response that was associated with significantly higher parasite loads, whereas WT mice were resistant. Flow cytometry and RT-PCR analyses showed overexpression of the mannose receptors, IL-4Rα, PDL2, arginase-1, Ym1, and RELM-α on MGL1(-/-) macrophages. These studies indicate that MGL1 is involved in T. crassiceps recognition and subsequent innate immune activation and resistance.
Assuntos
Antígenos de Helmintos/imunologia , Assialoglicoproteínas/metabolismo , Resistência à Doença/imunologia , Lectinas Tipo C/metabolismo , Macrófagos Peritoneais/metabolismo , Proteínas de Membrana/metabolismo , Transdução de Sinais , Taenia/imunologia , Teníase/imunologia , Acetilgalactosamina/metabolismo , Animais , Assialoglicoproteínas/deficiência , Citocinas/biossíntese , Feminino , Galactose/metabolismo , Glicoconjugados/metabolismo , Imunidade , Espaço Intracelular/metabolismo , Cinética , Lectinas Tipo C/deficiência , Ativação de Macrófagos/imunologia , Proteínas de Membrana/deficiência , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Fosforilação , Fosfotirosina/metabolismo , Ligação Proteica , Solubilidade , Teníase/parasitologiaRESUMO
Macrophage migration inhibitory factor (MIF) has been found to be involved in host resistance to several parasitic infections. To determine the mechanisms of the MIF-dependent responses to Trypanosoma cruzi, we investigated host resistance in MIFâ»/â» mice (on the BALB/c background) during an intraperitoneal infection. We focused on the potential involvement of MIF in dendritic cell (DC) maturation and cytokine production. Following a challenge with 5 x 10(3)T. cruzi parasites, wild type (WT) mice developed a strong IL-12 response and adequate maturation of the draining mesenteric lymph node DCs and were resistant to infection. In contrast, similarly infected MIFâ»/â» mice mounted a weak IL-12 response, displayed immature DCs in the early phases of infection and rapidly succumbed to T. cruzi infection. The lack of maturation and IL-12 production by the DCs in response to total T. cruzi antigen (TcAg) was confirmed by in vitro studies. These effects were reversed following treatment with recombinant MIF. Interestingly, TcAg-stimulated bone marrow-derived DCs from both WT and MIFâ»/â» mice had increased ERK1/2 MAPK phosphorylation. In contrast, p38 phosphorylation was only upregulated in WT DCs. Reconstitution of MIF to MIFâ»/â» DCs upregulated p38 phosphorylation. The MIF-p38 pathway affected MHC-II and CD86 expression as well as IL-12 production. These findings demonstrate that the MIF-induced early DC maturation and IL-12 production mediates resistance to T. cruzi infection, probably by activating the p38 pathway.
Assuntos
Antígenos de Protozoários/metabolismo , Interleucina-12/metabolismo , Fatores Inibidores da Migração de Macrófagos/metabolismo , Animais , Antígenos de Protozoários/genética , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Interferon gama/metabolismo , Interleucina-1beta/metabolismo , Fatores Inibidores da Migração de Macrófagos/genética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Fosforilação , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Cyclosporine A (CsA) is a fungus-derived molecule with potent immunosuppressive activity that has been largely used to downregulate cell-mediated immune responses during transplantation. However, previous data have indicated that CsA shows immunomodulatory activity that relays on the antigen concentration and the dose of CsA used. To test the hypothesis that minimal doses of CsA may show different outcomes on grafts, we used an experimental model for skin transplants in mice. ICR outbred mice received skin allografts and were either treated daily with different doses of CsA or left untreated. Untreated mice showed allograft rejection within 14 days, with graft necrosis, infiltration of neutrophils and macrophages and displayed high percentages of CD8+ T cells in the spleens, which were associated with high serum levels of IL-12, IFN-g and TNF-α. As expected, mice treated with therapeutic doses of CsA (15 mg/kg) did not show allograft rejection within the follow-up period of 30 days and displayed the lowest levels of IL-12, IFN-g and TNF-α as well as a reduction in CD8+ lymphocytes. In contrast, mice treated with consecutive minimal doses of CsA (5×10(-55) mg/kg) displayed an acute graft rejection as early as one to five days after skin allograft; they also displayed necrosis and strong inflammatory infiltration that was associated with high levels of IL-12, IFN-g and TNF-α. Moreover, the CD4+ CD25hiFoxP3+ subpopulation of cells in the spleens of these mice was significantly inhibited compared with animals that received the therapeutic treatment of CsA and those treated with placebo. Our data suggest that consecutive, minimal doses of CsA may affect Treg cells and may stimulate innate immunity.
Assuntos
Ciclosporina/efeitos adversos , Citocinas/metabolismo , Rejeição de Enxerto/induzido quimicamente , Imunossupressores/efeitos adversos , Transplante de Pele/imunologia , Animais , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD8-Positivos/efeitos dos fármacos , Ciclosporina/uso terapêutico , Feminino , Imunossupressores/uso terapêutico , Interleucina-12/metabolismo , Camundongos , Transplante Homólogo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
In cysticercosis, a parasitic disease caused by cestodes, the details of early interactions between parasite antigens and innate cells from the host are not well understood. In this study, the role of cestode-conditioned dendritic cells (DCs) in priming Th1 versus Th2 responses to bystander antigen was examined by using CD11c(+) DCs as antigen-presenting cells and naive CD4(+) DO11.10 lymphocytes specific to ovalbumin (OVA) as responding cells. No conventional maturation was induced in DCs exposed to Taenia crassiceps excreted/secreted antigens (TcES). The ability of TcES to affect Toll-like receptor (TLR)-mediated maturation and the pro-inflammatory response was analyzed by co-pulsing DCs with TcES and TLR ligands. DCs exposed to TcES blocked TLR4, TLR9 and Toxoplasma soluble antigen-induced phenotypic maturation. TcES-exposed DCs also blocked secretion of pro-inflammatory cytokines and alloreactive T cell proliferation, while preserving IL-10 production. DCs pulsed with TcES+OVA suppressed IFN-gamma, whereas they induced greater IL-4 production by CD4(+) DO11.10 cells. TcES with chemically-altered glycans failed to modulate TLR-mediated activation of DCs and their Th1-inhibitng ability, which was STAT6-independent. Our results reflect the capacity of TcES glyco-antigens to modulate Th1-type and inflammatory responses mediated through DC activation.
Assuntos
Antígenos de Helmintos/imunologia , Citocinas/biossíntese , Células Dendríticas/imunologia , Fator de Transcrição STAT6/imunologia , Transdução de Sinais , Taenia/imunologia , Células Th2/imunologia , Animais , Antígenos de Helmintos/química , Carboidratos/imunologia , Proliferação de Células , Células Cultivadas , Feminino , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Receptor 4 Toll-Like/antagonistas & inibidores , Receptor Toll-Like 9/antagonistas & inibidoresRESUMO
Parasitic infections are one of the most important causes of morbidity and mortality in our planet and the immune responses triggered by these organisms are critical to determine their outcome. Dendritic cells are key elements for the development of immunity against parasites; they control the responses required to eliminate these pathogens while maintaining host homeostasis. However, there is evidence showing that parasites can influence and regulate dendritic cell function in order to promote a more permissive environment for their survival. In this review we will focus on the strategies protozoan and helminth parasites have developed to interfere with dendritic cell activities as well as in the possible mechanisms involved.
Assuntos
Células Dendríticas/imunologia , Interações Hospedeiro-Parasita/imunologia , Parasitos/imunologia , Animais , HumanosRESUMO
Macrophage migration inhibitory factor (MIF) has been found to be involved in host resistance to several parasitic infections. To determine the mechanisms of MIF-dependent responses to Toxoplasma gondii, we investigated host resistance in MIF-/- mice (BALB/c background) during natural oral infection. We focused on the potential involvement of MIF in Dendritic Cell (DC) maturation and IL-12 production. Following oral T. gondii infection, wild type mice developed a strong IL-12 response with an adequate maturation of their draining mesenteric lymph node DC (MLNDC) population and were resistant to challenge with either 40 or 100 cysts (ME49 strain). In contrast, similarly infected MIF-/- mice mounted a weak IL-12 response, displayed immature MLNDCs in the early phases of infection and rapidly succumbed to both type of challenges. Lack of maturation and IL-12 production of DCs in response to T. gondii antigens was confirmed by in vitro studies, and these effects were reversed following treatment with recombinant MIF. These findings demonstrate that MIF-induced early DC maturation and IL-12 production mediate resistance to T. gondii infection.
Assuntos
Células Dendríticas/patologia , Interleucina-12/biossíntese , Oxirredutases Intramoleculares/genética , Fatores Inibidores da Migração de Macrófagos/genética , Toxoplasmose Animal/imunologia , Animais , Antígenos de Protozoários/imunologia , Encéfalo/parasitologia , Células Dendríticas/imunologia , Progressão da Doença , Suscetibilidade a Doenças/imunologia , Antígenos de Histocompatibilidade Classe II/metabolismo , Oxirredutases Intramoleculares/fisiologia , Fígado/parasitologia , Fígado/patologia , Fatores Inibidores da Migração de Macrófagos/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Organismos Livres de Patógenos Específicos , Toxoplasma/genética , Toxoplasma/crescimento & desenvolvimento , Toxoplasma/imunologia , Regulação para CimaRESUMO
To determine the role of alternatively activated macrophages in modulating the outcome of experimental cysticercosis caused by Taenia crassiceps, we investigated the effect of removal of alternatively activated macrophage by injecting clodronate-loaded liposomes into susceptible BALB/c mice. Following T. crassiceps infection, mice receiving PBS-loaded liposomes developed a dominant Th2-type response associated with the presence of alternatively activated macrophages together with antigen-specific hyporesponsiveness and high parasite burden. In contrast, similarly infected mice treated with clodronate-loaded liposomes mounted a mixed Th1/Th2-type response, reversed antigen-specific hyporesponsiveness and did not carry notable alternatively activated macrophage populations. These factors were associated with increased resistance to T. crassiceps cysticercosis. Interestingly, early AAM phi depletion was enough to limit parasite growth. However, if macrophages were depleted late in the infection, no effect on parasite burden was observed. These findings demonstrate that alternatively activated macrophages play a critical role in mediating susceptibility to experimental cysticercosis in which their early recruitment may favor parasite survival.
Assuntos
Cisticercose/imunologia , Cisticercose/parasitologia , Procedimentos de Redução de Leucócitos , Macrófagos/imunologia , Macrófagos/parasitologia , Taenia/imunologia , Animais , Feminino , Ativação de Macrófagos , Camundongos , Camundongos Endogâmicos BALB C , Células Th1/imunologia , Células Th2/imunologiaRESUMO
Antigen presenting cells (APCs) are critically involved in the interaction between pathogens and the host immune system. Here, we examined two different populations of APCs in mice that are susceptible (BALB/c) or resistant (C57BL/6) to Taenia crassiceps cysticercosis. Bone marrow-derived dendritic cells (BMDCs) from both strains of mice were exposed to T. crassiceps excreted/secreted antigens (TcES) and, at the same time, to the Toll-like receptor (TLR) ligand LPS. BMDCs from BALB/c mice underwent a partial maturation when incubated with TcES and displayed decreased responses to TLR-dependent stimuli associated with low CD80, CD86, CD40 and CCR7 expression and impaired IL-15 production. These BMDCs-induced impaired allogenic responses. In contrast, BMDCs from C57BL/6 mice displayed normal maturation and induced strong allogenic responses. Moreover, the exposure to TcES resulted in a lower production of IL-12 and TNF-alpha by LPS-activated DCs from BALB/c mice compared to C57BL/6 DCs. Three parameters of macrophage activation were assessed during Taenia infection: LPS+IFN-gamma-induced production of IL-12, TNF-alpha and nitric oxide (NO) in vitro; infection-induced markers for alternatively activated macrophages (Arginase-1, RELM-alpha, Ym-1 and TREM-2 expression) and suppressive activity. The maximum response to LPS+IFN-gamma-induced TNF-alpha, IL-12 and NO production by macrophages from both strains of mice occurred 2 wk post-infection. However, as infection progressed, the production of these molecules by BALB/c macrophages declined. While the BALB/c macrophages displayed impaired pro-inflammatory responses, these macrophages showed strong Arginase-1, Ym-1, RELM-alpha and TREM-2 expression. By contrast, C57BL/6 macrophages maintained a pro-inflammatory profile and low transcripts for alternative activation markers. Macrophages from T. crassiceps-infected BALB/c mice showed stronger suppressive activity than those from C57BL/6 mice. These findings suggest that APC activation at both early and late time points during T. crassiceps infection is a possible mechanism that underlies the differential susceptibility to T. crassiceps infection displayed by these mouse strains.
Assuntos
Células Dendríticas/imunologia , Predisposição Genética para Doença , Macrófagos/imunologia , Taenia/imunologia , Teníase/imunologia , Animais , Antígenos CD/biossíntese , Antígenos CD/sangue , Antígenos CD/imunologia , Antígenos de Protozoários/imunologia , Células Dendríticas/metabolismo , Feminino , Regulação da Expressão Gênica , Interações Hospedeiro-Parasita , Interleucinas/biossíntese , Interleucinas/sangue , Interleucinas/imunologia , Ativação de Macrófagos , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Teníase/genética , Teníase/metabolismo , Fatores de TempoRESUMO
We characterised a population of macrophages potentially involved in the immunoregulation induced by experimental cysticercosis. Following Taenia crassiceps infection, macrophages recruited in the peritoneal cavity were isolated and co-cultured at different ratios with T cells from naïve mice previously stimulated with anti-CD3/CD28 antibodies; these macrophages inhibited naïve T cell proliferation. This suppressive effect was Interleukin (IL)-10, Interferon-gamma (IFN-gamma), and nitric oxide (NO) independent. In contrast, macrophage-T cell contact was necessary to maintain anergy of T cells. Reverse transcriptase-PCR analysis of these macrophages showed higher transcripts of IL-10, chitinases Fizz1 and Ym1, and arginase-1 compared with naïve macrophages; by contrast, IL-12p40, and inducible nitric oxide synthase (iNOS) transcripts were undetected, whereas C-C chemokine ligand 5 (CCL5) was unchanged. Analysis of the membrane molecules expressed on Taenia-induced macrophages showed an up-regulation of several markers, mainly programmed death ligand 1 (PD-L1) and PD-L2. Blockade of PD-L1, PD-L2 or their receptor PD-1, but not of another marker, eliminated their ability to inhibit T-cell proliferation. Parallel experiments using ovalbumin (OVA)-peptide as a model antigen displayed similar results. Additionally, the same mechanism appears to be functional in splenocytes of T. crassiceps-infected mice given that blockade of PD-1, PD-L1 or PD-L2 re-established their ability to proliferate in response to parasite antigens. Moreover, Taenia-induced macrophages were able to suppress a mixed lymphocyte reaction in a PD-1-dependent manner. Thus, cestode infections induce macrophages alternatively activated with strong suppressive activity involving the PD-1/PD-L's pathway.