Functional Characterization of Aquaporin-4 Specific T Cells: Towards a Model for Neuromyelitis Optica

Antibodies to the water channel protein aquaporin-4 (AQP4), which is expressed in astrocytic endfeet at the blood brain barrier, have been identified in the serum of Neuromyelitis optica (NMO) patients and are believed to induce damage to astrocytes. However, AQP4 specific T helper cell responses that are required for the generation of anti-AQP4 antibodies and most likely also for the formation of intraparenchymal CNS lesions have not been characterized. specific T cells were present in the natural T cell repertoire of wild type C57BL/6 mice and T cell lines were raised. However, active immunization with these AQP4 peptides did not induce signs of spinal cord disease. Rather, sensitization with AQP4 peptides resulted in production of IFN-γ, but also IL-5 and IL-10 by antigen-specific T cells. Consistent with this cytokine profile, the AQP4 specific antibody response upon immunization with full length AQP4 included IgG1 and IgG2, which are associated with a mixed Th2/Th1 T cell response. restricted AQP4 specific T cell epitopes will allow us to investigate how AQP4 specific autoimmune reactions are regulated and to establish faithful mouse models of NMO that include both cellular and humoral responses against AQP4

An Oligopeptide Transporter of Mycobacterium tuberculosis Regulates Cytokine Release and Apoptosis of Infected Macrophages

Background: The Mycobacterium tuberculosis genome encodes two peptide transporters encoded by Rv3665c-Rv3662c and Rv1280c-Rv1283c. Both belong to the family of ABC transporters containing two nucleotide-binding subunits, two integral membrane proteins and one substrate-binding polypeptide. However, little is known about their functions in M. tuberculosis. Here we report functional characterization of the Rv1280c-Rv1283c-encoded transporter and its substrate-binding polypeptide OppA(MTB). Methodology/Principal Findings: OppA(MTB) was capable of binding the tripeptide glutathione and the nonapeptide bradykinin, indicative of a somewhat broad substrate specificity. Amino acid residues G109, N110, N230, D494 and F496, situated at the interface between domains I and III of OppA, were required for optimal peptide binding. Complementaton of an oppA knockout mutant of M. smegmatis with OppA(MTB) confirmed the role of this transporter in importing glutathione and the importance of the aforesaid amino acid residues in peptide transport. Interestingly, this transporter regulated the ability of M. tuberculosis to lower glutathione levels in infected compared to uninfected macrophages. This ability was partly offset by inactivation of oppD. Concomitantly, inactivation of oppD was associated with lowered levels of methyl glyoxal in infected macrophages and reduced apoptosis-inducing ability of the mutant. The ability to induce the production of the cytokines IL-1 beta, IL-6 and TNF-alpha was also compromised after inactivation of oppD. Conclusions: Taken together, these studies uncover the novel observations that this peptide transporter modulates the innate immune response of macrophages infected with M. tuberculosis

Intertextualité et forme dans le roman caribéen-canadien : de l’écriture dystopique de Neil Bissoondath au roman polysystémique de Ramabai Espinet

International audienc

Active Suppression Induced by Repetitive Self-Epitopes Protects against EAE Development

<div><p>Background</p><p>Autoimmune diseases result from a breakdown in self-tolerance to autoantigens. Self-tolerance is induced and sustained by central and peripheral mechanisms intended to deviate harmful immune responses and to maintain homeostasis, where regulatory T cells play a crucial role. The use of self-antigens in the study and treatment of a range of autoimmune diseases has been widely described; however, the mechanisms underlying the induced protection by these means are unclear. This study shows that protection of experimental autoimmune disease induced by T cell self-epitopes in a multimerized form (oligomers) is mediated by the induction of active suppression.</p><p>Principal Findings</p><p>The experimental autoimmune encephalomyelitis (EAE) animal model for multiple sclerosis was used to study the mechanisms of protection induced by the treatment of oligomerized T cell epitope of myelin proteolipid protein (PLP_139–151). Disease protection attained by the administration of oligomers was shown to be antigen specific and effective in both prevention and treatment of ongoing EAE. Oligomer mediated tolerance was actively transferred by cells from treated mice into adoptive hosts. The induction of active suppression was correlated with the recruitment of cells in the periphery associated with increased production of IL-10 and reduction of the pro-inflammatory cytokine TNF-α. The role of suppressive cytokines was demonstrated by the reversion of oligomer-induced protection after <i>in vivo</i> blocking of either IL-10 or TGF-β cytokines.</p><p>Conclusions</p><p>This study strongly supports an immunosuppressive role of repeat auto-antigens to control the development of EAE with potential applications in vaccination and antigen specific treatment of autoimmune diseases.</p></div