Project description:Determination of the mechanism by which fibrinogen, a central blood coagulation protein drives immunological responses targeted to the CNS. Results identify the factors involved in the regulation and provide mechanistic basis. We subjected fibrinogen-injected corpus callosum to microarray to determine the genes involved in innate and adaptive immune responses by fibrinogen deposited in the CNS after blood-brain barrier disruption. Corpus callosum tissues were isolated from mice received stereotactic injection of fibrinogen or ACSF at 12 hr. Tissues were subjected for RNA extraction and hybridization on Affymatrix microarrays. Two ACSF and two fibrinogen samples were generated.
Project description:Determination of the mechanism by which fibrinogen, a central blood coagulation protein drives immunological responses targeted to the CNS. Results identify the factors involved in the regulation and provide mechanistic basis. We subjected fibrin-stimulated microglia to microarray to determine the genes involved in innate and adaptive immune responses by fibrinogen deposited in the CNS after blood-brain barrier disruption. Rat microglia were stimulated with fibrin for 6 hr and subjected for RNA extraction and hybridization on Affymatrix microarrays. Two unstimulated and two fibrin-stimulated samples were generated.
Project description:Determination of the mechanism by which fibrinogen, a central blood coagulation protein drives immunological responses targeted to the CNS. Results identify the factors involved in the regulation and provide mechanistic basis. We subjected fibrin-stimulated microglia to microarray to determine the genes involved in innate and adaptive immune responses by fibrinogen deposited in the CNS after blood-brain barrier disruption.
Project description:Determination of the mechanism by which fibrinogen, a central blood coagulation protein drives immunological responses targeted to the CNS. Results identify the factors involved in the regulation and provide mechanistic basis. We subjected fibrinogen-injected corpus callosum to microarray to determine the genes involved in innate and adaptive immune responses by fibrinogen deposited in the CNS after blood-brain barrier disruption.
Project description:Autoimmunity and macrophage recruitment into the central nervous system (CNS) are critical determinants of neuroinflammatory diseases. However, the mechanisms that drive immunological responses targeted to the CNS remain largely unknown. Here we show that fibrinogen, a central blood coagulation protein deposited in the CNS after blood-brain barrier disruption, induces encephalitogenic adaptive immune responses and peripheral macrophage recruitment into the CNS leading to demyelination. Fibrinogen stimulates a unique transcriptional signature in CD11b(+) antigen-presenting cells inducing the recruitment and local CNS activation of myelin antigen-specific Th1 cells. Fibrinogen depletion reduces Th1 cells in the multiple sclerosis model, experimental autoimmune encephalomyelitis. Major histocompatibility complex (MHC) II-dependent antigen presentation, CXCL10- and CCL2-mediated recruitment of T cells and macrophages, respectively, are required for fibrinogen-induced encephalomyelitis. Inhibition of the fibrinogen receptor CD11b/CD18 protects from all immune and neuropathologic effects. Our results show that the final product of the coagulation cascade is a key determinant of CNS autoimmunity.
Project description:A number of autoimmunity-associated MHC class II proteins interact only weakly with the invariant chain-derived class II-associated invariant chain peptide (CLIP). CLIP dissociates rapidly from I-Ag7 even in the absence of DM, and this property is related to the type 1 diabetes-associated β57 polymorphism. We generated knock-in non-obese diabetic (NOD) mice with a single amino acid change in the CLIP segment of the invariant chain in order to moderately slow CLIP dissociation from I-Ag7 These knock-in mice had a significantly reduced incidence of spontaneous type 1 diabetes and diminished islet infiltration by CD4 T cells, in particular T cells specific for fusion peptides generated by covalent linkage of proteolytic fragments within β cell secretory granules. Rapid CLIP dissociation enhanced the presentation of such extracellular peptides, thus bypassing the conventional MHC class II antigen-processing pathway. Autoimmunity-associated MHC class II polymorphisms therefore not only modify binding of self-peptides, but also alter the biochemistry of peptide acquisition.
Project description:A number of autoimmunity-associated MHC class II proteins interact only weakly with the invariant chain-derived class II-associated invariant chain peptide (CLIP). CLIP dissociates rapidly from I-Ag7 even in the absence of DM, and this property is related to the type 1 diabetes-associated b57 polymorphism. We generated knock-in Non-obese Diabetic (NOD) mice with a single amino acid change in the CLIP segment of invariant chain in order to moderately slow CLIP dissociation from I-Ag7. These knock-in mice had a significantly reduced incidence of spontaneous type 1 diabetes and diminished islet infiltration by CD4 T cells, in particular T cells specific for fusion peptides generated by covalent linkage of proteolytic fragments within b cell secretory granules. Rapid CLIP dissociation enhanced presentation of such extracellular peptides, thus bypassing the conventional MHC class II antigen processing pathway. Autoimmunity-associated MHC class II polymorphisms therefore not only modify binding of self-peptides, but also alter the biochemistry of peptide acquisition.
Project description:Dendritic cells (DCs) present foreign antigen in major histocompatibility complex (MHC) class I molecules to cytotoxic T cells in a process called cross-presentation. An important step in this process is the release of antigen from the lumen of endosomes into the cytosol, but the mechanism of this step is still unclear. In this study, we show that reactive oxygen species (ROS) produced by the NADPH-oxidase complex NOX2 cause lipid peroxidation, a membrane disrupting chain-reaction, which in turn results in antigen leakage from endosomes. Antigen leakage and cross-presentation were inhibited by blocking ROS production or scavenging radicals and induced when using a ROS-generating photosensitizer. Endosomal antigen release was impaired in DCs from chronic granulomatous disease (CGD) patients with dysfunctional NOX2. Thus, NOX2 induces antigen release from endosomes for cross-presentation by direct oxidation of endosomal lipids. This constitutes a new cellular function for ROS in regulating immune responses against pathogens and cancer.
Project description:Presentation of tissue-restricted antigens (TRA) in the thymus is essentialfor establishing self-tolerancethrough elimination of autoreactive Tcells.It remains unclear why certain self T cells can bypassthymic selectionand become driversoftissue-specific autoimmunity. Herewe assessedthymic TRA presented by a major histocompatibility class II molecule (MHC-II) that confers genetic propensity to develop type 1 diabetes. This analysisestablished the thymic peptidome containing self-peptidesderivedfrom variousperipheral tissues,butalso revealed a disparity in the MHC-II epitoperepertoirebetween thymus and the target site of autoimmunity, the pancreatic islets.The thymic repertoire consistedof canonicalMHC-IIepitopes capable of enforcing central tolerance but lacked presentation of uniqueepitopes derived from unconventionalself-proteinprocessing orneoepitopes formed by post-translational modifications. Suchepitopes were noteworthily generatedin the isletsvia a tissue-intrinsic mechanism, crinophagy, and were recognized by CD4 T cells escaping central tolerance.These findings supportthat central tolerance mechanisms are effective but incomplete, as tissue-characteristic handling of self-antigens may broaden the peripheralrepertoire thatextends beyond the scope of thymic selection.