Human T Cell and Antibody-Mediated Responses to the Mycobacterium tuberculosis Recombinant 85A, 85B, and ESAT-6 Antigens

Tuberculosis remains a major health problem throughout the world causing large number of deaths. Effective disease control and eradication programs require the identification of major antigens recognized by the protective responses against M. tuberculosis. In this study, we have investigated humoral and cellular immune responses to M. tuberculosis-specific Ag85A, Ag85B, and ESAT-6 antigens in Brazilian patients with pulmonary (P, n = 13) or extrapulmonary (EP, n = 12) tuberculosis, patients undergoing chemotherapy (PT, n = 23), and noninfected healthy individuals (NI, n = 7). Compared to NI, we observed increased levels of IgG1 responses to Ag85B and ESAT-6 in P and PT groups. Regarding cellular immunity, Ag85A and ESAT-6 were able to discriminate P, PT, and EP patients from healthy individuals by IFN-γ production and P and PT groups from EP individuals by production of TNF-α. In summary, these findings demonstrate the ability of Ag85A, Ag85B, and ESAT-6 to differentiate TB patients from controls by IgG1, IFN-γ and TNF-α production

TLR9 regulates Th1 responses and cooperates with TLR2 in mediating optimal resistance to Mycobacterium tuberculosis

To investigate the role of Toll-like receptor (TLR)9 in the immune response to mycobacteria as well as its cooperation with TLR2, a receptor known to be triggered by several major mycobacterial ligands, we analyzed the resistance of TLR9−/− as well as TLR2/9 double knockout mice to aerosol infection with Mycobacterium tuberculosis. Infected TLR9−/− but not TLR2−/− mice displayed defective mycobacteria-induced interleukin (IL)-12p40 and interferon (IFN)-γ responses in vivo, but in common with TLR2−/− animals, the TLR9−/− mice exhibited only minor reductions in acute resistance to low dose pathogen challenge. When compared with either of the single TLR-deficient animals, TLR2/9−/− mice displayed markedly enhanced susceptibility to infection in association with combined defects in proinflammatory cytokine production in vitro, IFN-γ recall responses ex vivo, and altered pulmonary pathology. Cooperation between TLR9 and TLR2 was also evident at the level of the in vitro response to live M. tuberculosis, where dendritic cells and macrophages from TLR2/9−/− mice exhibited a greater defect in IL-12 response than the equivalent cell populations from single TLR9-deficient animals. These findings reveal a previously unappreciated role for TLR9 in the host response to M. tuberculosis and illustrate TLR collaboration in host resistance to a major human pathogen

Inclusão, arte e docência: caminhos para a inovação pedagógica

O Observatório Internacional de Inclusão, Interculturalidade e Inovação Pedagógica tem nos proposto, enquanto professores pesquisadores, repensar nossos processos formativos e os processos de formação que praticamos, de forma colaborativa. Neste trabalho, pretendemos refletir sobre a docência em tempos de discurso universitário impactado pelos rumos do capitalismo atual, em que a autoria do professor pode ser um desafio, proposto na construção permanente de uma docência sempre em questão. Em virtude da pulverização do estilo e da subjetividade do professor na atualidade, vivemos uma constante demanda por aperfeiçoamento. Além disso, quanto mais se amplia o direito à educação, quanto mais se universaliza a educação básica e se democratiza o acesso ao ensino superior, mais entram para o espaço escolar sujeitos antes invisibilizados ou desconsiderados como sujeitos de conhecimento. Para tornar a educação um espaço de diálogo entre tamanha variabilidade, precisamos buscar novos caminhos para a inovação pedagógica que se faz necessária. Mas o que seria inovação pedagógica? Nossa proposta é nos posicionar e pensar esse conceito em articulação com o processo de inclusão e interculturalidade. Neste sentido, elegemos, entre outros, a arte como um dos recursospotenciais para o questionamento de currículos ainda colonizados e colonizadores. Refletir, criar e debater são ações que defendemos como resposta às exigências emancipatórias do presente momento histórico e do cenário político em que estamos imersos

TAP-1 indirectly regulates CD4+ T cell priming in Toxoplasma gondii infection by controlling NK cell IFN-γ production

To investigate if transporter associated with antigen processing (TAP)–1 is required for CD8+ T cell–mediated control of Toxoplasma gondii in vivo, we compared the resistance of TAP-1−/−, CD8−/−, and wild-type (WT) mice to infection with the parasite. Unexpectedly, TAP-1−/− mice displayed greater susceptibility than CD8−/−, β2-microglobulin−/− (β2m−/−), or WT mice to infection with an avirulent parasite strain. The decreased resistance of the TAP-1−/− mice correlated with a reduction in the frequency of activated (CD62Llow CD44hi) and interferon (IFN)-γ–producing CD4+ T cells. Interestingly, infected TAP-1−/− mice also showed reduced numbers of IFN-γ–producing natural killer (NK) cells relative to WT, CD8−/−, or β2m−/− mice, and after NK cell depletion both CD8−/− and WT mice succumbed to infection with the same kinetics as TAP-1−/− animals and displayed impaired CD4+ T cell IFN-γ responses. Moreover, adoptive transfer of NK cells obtained from IFN-γ+/+, but not IFN-γ−/−, animals restored the CD4+ T cell response of infected TAP-1−/− mice to normal levels. These results reveal a role for TAP-1 in the induction of IFN-γ–producing NK cells and demonstrate that NK cell licensing can influence host resistance to infection through its effect on cytokine production in addition to its role in cytotoxicity

Differential arabinan capping of lipoarabinomannan modulates innate immune responses and impacts T helper cell differentiation

We acknowledge scientific discussions with Drs. Anne O'Garra, Luke Alderwick, and Apoorva Bhatt.Background: Lipoglycans modulate the initiation of immune responses by interacting with TLR2. Results: A hypermannosylated lipomannan variant, once recognized by the immune system, enhance both innate responses and Th17 differentiation. Conclusion: Altered lipoglycan structures are differently recognised by innate immune cells with an impact on the adaptive immune response. Significance: Specific lipoglycan structures may be useful to modulate immune responses. Resume: Toll-like receptors (TLRs) recognize pathogens by interacting with pathogen-associated molecular patterns, such as the phosphatidylinositol-based lipoglycans, lipomannan (LM) and lipoarabinomannan (LAM). Such structures are present in several pathogens, including Mycobacterium tuberculosis, being important for the initiation of immune responses. It is well established that the interaction of LM and LAM with TLR2 is a process dependent on the structure of the ligands. However, the implications of structural variations on TLR2 ligands for the development of T helper (Th) cell responses or in the context of in vivo responses are less studied. Herein, we used Corynebacterium glutamicum as a source of lipoglycan intermediates for host interaction studies. In this study, we have deleted a putative glycosyltransferase, NCgl2096, from C. glutamicum and found that it encodes for a novel α(1→2)arabinofuranosyltransferase, AftE. Biochemical analysis of the lipoglycans obtained in the presence (wild type) or absence of NCgl2096 showed that AftE is involved in the biosynthesis of singular arabinans of LAM. In its absence, the resulting molecule is a hypermannosylated (hLM) form of LAM. Both LAM and hLM were recognized by dendritic cells, mainly via TLR2, and triggered the production of several cytokines. hLM was a stronger stimulus for in vitro cytokine production and, as a result, a more potent inducer of Th17 responses. In vivo data confirmed hLM as a stronger inducer of cytokine responses and suggested the involvement of pattern recognition receptors other than TLR2 as sensors for lipoglycans.Margarida Saraiva Supported by Fundação para a Ciência e Tecnologia (FCT), Portugal, Personal Grant PTDC/SAU-MII/101977/2008; Gurdyal S. Besra Supported by a Personal Research Chair from James Bardrick, a Royal Society Wolfson Research Merit Award, a Lister Institute-Jenner research fellowship, the Medical Research Council, and Wellcome Trust Grant 081569/Z/06/Z. António G. Castro Supported by FCT, Portugal, Project Grant PTDC/SAU-MII/101977/2008. Jeroen Geurtsen Supported by the Netherlands Organization for Scientific Research (NWO) through a VENI research grant (016.101.001)

TLR9 activation is a key event for the maintenance of a mycobacterial antigen-elicited pulmonary granulomatous response

Type 1 (Th1) granulomas can be studied in mice sensitized with mycobacterium antigens followed by challenge of agarose beads covalently coupled to purified protein derivative. TLR9 is known to play a role in the regulation of Th1 responses; thus, we investigated the role of TLR9 in granuloma formation during challenge with mycobacterium antigens and demonstrated that mice deficient in TLR9 had increased granuloma formation, but a dramatically altered cytokine phenotype. Th1 cytokine levels of IFN-γ and IL-12 in the lungs were decreased in TLR9 –/– mice when compared to wild-type mice. In contrast, Th2 cytokine levels of IL-4, IL-5, and IL-13 were increased in TLR9 –/– mice. The migration of CD4 + T cells in the granuloma was impaired, while the number of F4/80 + macrophages was increased in TLR9 –/– mice. Macrophages in the lungs of the TLR9-deficient animals with developing granulomas expressed significantly lower levels of the classically activated macrophage marker, nitric oxide synthase, but higher levels of the alternatively activated macrophage markers such as ‘found in inflammatory zone-1′ antigen and Arginase-1. These results suggest that TLR9 plays an important role in maintaining the appropriate phenotype in a Th1 granulomatous response.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57331/1/2847_ftp.pd

TLR2 deficiency by compromising p19 (IL-23) expression limits T helper 17 cell responses to Mycobacterium tuberculosis

The authors are grateful to Drs. Manuel Teixeira da Silva, Fernando Rodrigues, Margarida Correia-Neves and Paul S. Redford for critically reading this manuscript and thank the personnel at the ICVS animal house facility for excellent animal husbandry.CD4+ Th1 cells producing IFN-γ are of extreme importance in controlling infections by Mycobacterium tuberculosis both in mice and in men. In addition to IFN-γ-producing T cells, IL-17-producing T cells (Th17) have been observed during mycobacterial infections. Nevertheless, their contribution for the host immune response to mycobacteria as well as the signals triggering M. tuberculosis -specific Th17 cell differentiation and maintenance are not fully understood. We show that signaling via Toll-like receptor (TLR) 2 has a major impact on the regulation of p19 (IL-23) expression in response to M. tuberculosis and therefore on the establishment of Th17 cell responses to M. tuberculosis infection. Diminished Th17 responses in the lung of M. tuberculosis -infected TLR2-deficient animals were not caused by defective cell differentiation in the draining lymph node (LN) but rather by reduced maintenance at the site of infection. Consistent with the decreased numbers of Th17 cells in the lungs of infected TLR2-deficient animals, we observed reduced expression of CXCL9, CXCL10 and CXCL11, chemokines involved in recall responses to M. tuberculosis. Our data provides insights into the TLR2 role in infection with M. tuberculosis, with implications in pathophysiology of the disease and vaccine design.Fundação para a Ciência e Tecnologia, Portugal (Project Grants PTDC/SAU/70895/2006 to AGC and PTDC/BIA-BCM/102776/2008 to MS; and Personal Grants SRFH/BD/33034/2006 to MTC; SFRH/BPD/3306/2007 to AC; SFRH/BD/35981/2007 to JC; SFRH/BI/33456/2008 to CS and PTDC/SAU-MII/70895/2006 to DRP) and by the Health Service of Fundação Calouste Gulbenkian. MS is a Ciência 2007 Fellow

SOCS2-Induced Proteasome-Dependent TRAF6 Degradation: A Common Anti-Inflammatory Pathway for Control of Innate Immune Responses

Pattern recognition receptors and receptors for pro-inflammatory cytokines provide critical signals to drive the development of protective immunity to infection. Therefore, counter-regulatory pathways are required to ensure that overwhelming inflammation harm host tissues. Previously, we showed that lipoxins modulate immune response during infection, restraining inflammation during infectious diseases in an Aryl hydrocarbon receptor (AhR)/suppressors of cytokine signaling (SOCS)2-dependent-manner. Recently, Indoleamine-pyrrole 2,3- dioxygenase (IDO)-derived tryptophan metabolites, including L-kynurenine, were also shown to be involved in several counter-regulatory mechanisms. Herein, we addressed whether the intracellular molecular events induced by lipoxins mediating control of innate immune signaling are part of a common regulatory pathway also shared by L-kynurenine exposure. We demonstrate that Tumor necrosis factor receptor-associated factor (TRAF)6 – member of a family of adapter molecules that couple the TNF receptor and interleukin-1 receptor/Toll-like receptor families to intracellular signaling events essential for the development of immune responses – is targeted by both lipoxins and L-kynurenine via an AhR/SOCS2-dependent pathway. Furthermore, we show that LXA4- and L-kynurenine-induced AhR activation, its subsequent nuclear translocation, leading SOCS2 expression and TRAF6 Lys47-linked poly-ubiquitination and proteosome-mediated degradation of the adapter proteins. The in vitro consequences of such molecular interactions included inhibition of TLR- and cytokine receptor-driven signal transduction and cytokine production. Subsequently, in vivo proteosome inhibition led to unresponsiveness to lipoxins, as well as to uncontrolled pro-inflammatory reactions and elevated mortality during toxoplasmosis. In summary, our results establish proteasome degradation of TRAF6 as a key molecular target for the anti-inflammatory pathway triggered by lipoxins and L-kynurenine, critical counter-regulatory mediators in the innate and adaptive immune systems