Inflammatory Properties and Adjuvant Potential of Synthetic Glycolipids Homologous to Mycolate Esters of the Cell Wall of Mycobacterium tuberculosis

&lt;p&gt;The cell wall of mycobacteria is characterised by glycolipids composed of different classes of mycolic acids (MAs; alpha-, keto-, and methoxy-) and sugars (trehalose, glucose, and arabinose). Studies using mutant Mtb strains have shown that the structure of MAs influences the inflammatory potential of these glycolipids. As mutant Mtb strains possess a complex mixture of glycolipids, we analysed the inflammatory potential of single classes of mycolate esters of the Mtb cell wall using 38 different synthetic analogues. Our results show that synthetic trehalose dimycolate (TDM) and trehalose, glucose, and arabinose monomycolates (TMM, GMM, and AraMM) activate bone marrow-derived dendritic cells in terms of the production of pro-inflammatory cytokines (IL-6 and TNF-&amp;alpha;) and reactive oxygen species, upregulation of costimulatory molecules, and activation of NLRP3 inflammasome by a mechanism dependent on Mincle. These findings demonstrate that Mincle receptor can also recognise pentose esters and seem to contradict the hypothesis that production of GMM is an escape mechanism used by pathogenic mycobacteria to avoid recognition by the innate immune system. Finally, our experiments indicate that TMM and GMM, as well as TDM, can promote Th1 and Th17 responses in mice in an OVA immunisation model, and that further analysis of their potential as novel adjuvants for subunit vaccines is warranted.&lt;/p&gt;</p

TBVAC2020 : advancing tuberculosis vaccines from discovery to clinical development

TBVAC2020 is a research project supported by the Horizon 2020 program of the European Commission (EC). It aims at the discovery and development of novel tuberculosis (TB) vaccines from preclinical research projects to early clinical assessment. The project builds on previous collaborations from 1998 onwards funded through the EC framework programs FP5, FP6, and FP7. It has succeeded in attracting new partners from outstanding laboratories from all over the world, now totaling 40 institutions. Next to the development of novel vaccines, TB biomarker development is also considered an important asset to facilitate rational vaccine selection and development. In addition, TBVAC2020 offers portfolio management that provides selection criteria for entry, gating, and priority settings of novel vaccines at an early developmental stage. The TBVAC2020 consortium coordinated by TBVI facilitates collaboration and early data sharing between partners with the common aim of working toward the development of an effective TB vaccine. Close links with funders and other consortia with shared interests further contribute to this goal

TBVAC2020: Advancing tuberculosis vaccines from discovery to clinical development

TBVAC2020 is a research project supported by the Horizon 2020 program of the European Commission (EC). It aims at the discovery and development of novel tuberculosis (TB) vaccines from preclinical research projects to early clinical assessment. The project builds on previous collaborations from 1998 onwards funded through the EC framework programs FP5, FP6, and FP7. It has succeeded in attracting new partners from outstanding laboratories from all over the world, now totaling 40 institutions. Next to the development of novel vaccines, TB biomarker development is also considered an important asset to facilitate rational vaccine selection and development. In addition, TBVAC2020 offers portfolio management that provides selection criteria for entry, gating, and priority settings of novel vaccines at an early developmental stage. The TBVAC2020 consortium coordinated by TBVI facilitates collaboration and early data sharing between partners with the common aim of working toward the development of an effective TB vaccine. Close links with funders and other consortia with shared interests further contribute to this goal

Inflammatory power and adjuvant potential of synthetic glycolipids homologous to mycolate esters of Mycobacterium tuberculosis

Tuberculosis (TB) is caused by Mycobacterium tuberculosis (Mtb) infection and remains a major global cause of morbidity and mortality. The cell wall of mycobacteria is characterized by long chain fatty acid called mycolic acids (MAs), which are found free or esterified to different sugars. In Mtb, the main classes of MAs present are alpha-, methoxy- and keto-MAs and they differ in their ability to induce lung inflammation. Studies using Mtb strains mutated in the synthesis pathways of MAs have shown that the class of MA bound to trehalose influences its inflammatory power. But the cell wall of Mtb contains variable mixture of MAs and mycolates with different chain lengths. The contribution of all these different classes of mycolates to the inflammatory power of Mtb and their interaction with the different pattern recognition receptors is not clear. In this study, we address the relationship between the structure of the mycolate esters and the inflammatory power in vitro using synthetic mycolates.Inflammatory power and adjuvant potential of synthetic glycolipids homologous to mycolate esters of Mycobacterium tuberculosi

Innate signaling by mycolate esters of the cell wall of Mycobacterium tuberculosis and relevance for the development of adjuvants for subunit vaccines

Tuberculosis remains among the most deadly health threats to humankind. This povertyrelated disease, caused by bacteria of the Mycobacterium tuberculosis complex, kills each year more than 1.5 million people. It is estimated that a further 2 billion individuals are latently infected with M. tuberculosis. Most of them will never develop any clinical symptoms, although 5 to 10% of these latently infected individuals are at risk to develop TB in their lifetime. During the last decades the situation worsened because of deteriorating socioeconomic conditions, the increased incidence of drug-resistant M.tuberculosis strains and the co-infection with HIV (a major risk factor for development of TB). Currently only one vaccine is available against TB, the Bacille of Calmette and Guérin (BCG). However, its efficacy is extremely variable against the contagious form of TB - pulmonary TB - in adults and adolescents (ranging from 0 to 80%). Therefore, to control and eliminate TB, a better vaccine, efficient drug treatments and more rapid and cheaper diagnostic techniques are needed. In this PhD thesis we have attempted to provide additional information to reach this goal. Indeed, we investigated the inflammatory and adjuvant potential of mycolate esters homologous of those found in the cell wall of M. tuberculosis. These mycolate esters vary in terms of sugar (trehalose, glucose and arabinose) and lipid (alpha-, methoxy-, keto-, wax-ester MAs) moieties. TDM, TMM, GMM and AraMM were found to be potent activators of BMDCs in vitro. This activation was shown to be dependent on the Mincle pathway. Our results demonstrated that the classes of MAs bound to sugar do not consistently impact the level of pro-inflammatory and adjuvant responses induced. Rather, the nature of the sugar and the number of acyl chains bound to it seem to dictate the affinity of the glycolipid for Mincle receptor in vitro. In vivo, we observed that TDM, TMM and GMM induce similar immune responses characterized by a production of antigen-specific IFN-γ and IL-17A. The immune responses induced by AraMM are dependent on the type of formulation. Indeed, AraMM in emulsion does not induce substantial level of Th1 while AraMM in DDA liposome induces Th1 immune response. This study increases our knowledge on host-pathogen interactions during M. tuberculosis infection by identifying the receptor involved in the recognition of several PAMPs. Furthermore, we showed that the activation of this receptor by these mycolate esters triggers the induction of protective Th1 and Th17 immune response

Innate signaling by mycobacterial cell wall components and relevance for development of adjuvants for subunit vaccines.

&lt;p&gt;&lt;b&gt;INTRODUCTION: &lt;/b&gt;Pathogen recognition receptors (PRRs) recognize pathogen-associated molecular patterns, triggering the induction of inflammatory innate responses and contributing to the development of specific adaptive immune responses. Novel adjuvants have been developed based on agonists of PRRs. Areas covered: Lipid pathogen-associated molecular patterns (PAMPs) present in the cell wall of mycobacteria are revised, with emphasis on agonists of C-type lectin receptors, signaling pathways, and preclinical data supporting their use as novel adjuvants inducing cell-mediated immune responses. Their potential use as lipid antigens in novel tuberculosis subunit vaccines is also discussed. Expert commentary: Few adjuvants are licensed for human use and mainly favour antibody-mediated protective immunity. Use of lipid PAMPs that trigger cell-mediated immune responses could lead to the development of adjuvants for vaccines against intracellular pathogens and cancer.&lt;/p&gt;</p

Synthesis of wax esters and related trehalose esters from mycobacterium avium and other mycobacteria

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Aspergillus fumigatus recognition by dendritic cells negatively regulates allergic lung inflammation through a TLR2/MyD88 pathway

Aspergillus fumigatus is an opportunistic fungal pathogen responsible for a spectrum of clinical manifestations. Dendritic cells recognize pathogen-associated molecular patterns of Aspergillus via two main receptor families, Toll-like receptors (TLRs) and C-type lectin receptors (CLR). Here, the importance of TLR and CLR signaling in the regulation of T-helper cell type 2 (Th2) responses was analyzed using a mouse model based on the transfer of bone marrow-derived dendritic cells (BMDCs) pulsed with A. fumigatus conidia. BMDCs were generated from mice deficient in either MyD88 or MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1). Both the MyD88 and MALT1 signaling pathway in BMDCs contributed to the production of inflammatory cytokines induced by A. fumigatus conidia. Mice sensitized with MyD88(-/-) BMDCs pulsed in vitro with A. fumigatus conidia showed an exacerbated allergic inflammation, with stronger eosinophil recruitment in the BAL and higher Th2 cytokine production compared with mice sensitized with wild-type or MALT1(-/-) BMDCs. This exacerbation was not observed when MyD88(-/-) BMDCs were pulsed with Cladosporium sphaerospermum, a nonpathogenic mold. A lack of TLR2 signaling recapitulated the exacerbation of the A. fumigatus Th2 response observed in the absence of MyD88 signaling, whereas TLR2 agonist dampened the response induced with A. fumigatus and C. sphaerospermum conidia. IL-10 production by BMDCs in response to A. fumigatus was dependent on the expression of TLR2 and MyD88. IL-10(-/-) BMDCs exacerbated, whereas MyD88(-/-) BMDCs supplemented with exogenous IL-10 decreased the allergic pulmonary inflammation. These results indicate that TLR2/MyD88-specific recognition of PAMPs from A. fumigatus conidia can upregulate IL-10 production and downregulate lung eosinophilia and the development of a Th2 response

MALT1 controls attenuated rabies virus by inducing early inflammation and T cell activation in the brain.

&lt;p&gt;MALT1 is involved in the activation of immune responses as well as in the proliferation and survival of certain cancer cells. MALT1 acts as a scaffold protein for NF-&amp;kappa;B signalling and a cysteine protease that cleaves substrates, further promoting the expression of immunoregulatory genes. Deregulated MALT1 activity has been associated with autoimmunity and cancer, implicating MALT1 as a new therapeutic target. While MALT1 deficiency has been shown to protect against experimental autoimmune encephalomyelitis, nothing is known about the impact of MALT1 on virus infection in the central nervous system. Here, we studied infection with an attenuated rabies virus (ERA) and observed increased susceptibility with ERA in MALT1-/- mice. Indeed, following intranasal infection with ERA, wild-type mice developed mild transient clinical signs with recovery at 35 DPI. Interestingly, MALT1-/- mice developed severe disease requiring euthanasia around 17 DPI. A decreased induction of inflammatory gene expression and cell infiltration and activation was observed in MALT1-/- mice at 10DPI as compared to MALT1+/+ infected mice. At 17 DPI, however, inflammatory cell activation was comparable to the one observed in MALT1+/+ mice. Moreover, MALT1-/- mice failed to produce virus-neutralizing antibodies. Similar results were obtained with specific inactivation of MALT1 in T cells. Finally, treatment of wild-type mice with mepazine, a MALT1 protease inhibitor, also led to mortality upon ERA virus infection. These data emphasize the importance of early inflammation and activation of T cells through MALT1 for controlling the virulence of an attenuated rabies virus in the brain.IMPORTANCE Rabies virus is a neurotropic virus which can infect any mammal. Annually, 59000 people die from rabies. Effective therapy is lacking and hampered by gaps in the understanding of virus pathogenicity. MALT1 is an intracellular protein involved in innate and adaptive immunity, and an interesting therapeutic target because MALT1-deregulated activity has been associated with autoimmunity and cancers. The role of MALT1 in viral infection is however largely unknown. Here, we study the impact of MALT1 on virus infection in the brain, using the attenuated ERA rabies virus in different models of MALT1 deficient mice. We reveal the importance of MALT1-mediated inflammation and T cell activation to control ERA virus, providing new insights in the biology of MALT1 and rabies virus infection.&lt;/p&gt;</p

Trypanosoma infection favors Brucella elimination via IL-12/IFNγ-dependent pathways

This study develops an original co-infection model in mice using Brucella melitensis, the most frequent cause of human brucellosis, and Trypanosoma brucei, the agent of African trypanosomiasis. Although the immunosuppressive effects of T. brucei in natural hosts and mice models are well established, we observed that the injection of T. brucei in mice chronically infected with B. melitensis induces a drastic reduction in the number of B. melitensis in the spleen, the main reservoir of the infection. Similar results are obtained with Brucella abortus- and Brucella suis-infected mice and B. melitensis-infected mice co-infected with Trypanosoma cruzi, demonstrating that this phenomenon is not due to antigenic cross-reactivity. Comparison of co-infected wild-type and genetically deficient mice showed that Brucella elimination required functional IL-12p35/IFNγ signaling pathways and the presence of CD4 T cells. However, the impact of wild type and an attenuated mutant of T. brucei on B. melitensis were similar, suggesting that a chronic intense inflammatory reaction is not required to eliminate B. melitensis. Finally, we also tested the impact of T. brucei infection on the course of Mycobacterium tuberculosis infection. Although T. brucei strongly increases the frequency of IFNγCD4 T cells, it does not ameliorate the control of M. tuberculosis infection, suggesting that it is not controlled by the same effector mechanisms as Brucella. Thus, whereas T. brucei infections are commonly viewed as immunosuppressive and pathogenic, our data suggest that these parasites can specifically affect the immune control of Brucella infection, with benefits for the host