Project description:Discovery of immune tolerance mechanisms, which inhibit pre-existing autoimmune inflammation, may provide us with new strategies for treating autoimmune diseases. We have identified a CD8αα+MHC-II+ cell with professional APC capacity during our investigation on spontaneous recovery from autoimmune glomerulonephritis in a rat model. This cell actively invades inflamed target tissue to terminate an on-going autoimmune inflammation by selective killing of effector autoreactive T cells. Now, we showed that this cell used a cytotoxic machinery of Ly49s+ NK cells in killing of target T cells. Thus, this CD8αα+MHC-II+ cell, which previously was thought a professional APC, is an antigen presenting-NK (AP-NK) cell. Following its coupling with target T cells through antigen presentation, killing stimulatory receptor Ly49s6 and co-receptor CD8αα on this cell used non-classic MHC-I RT1CE16 on the target T cells as a ligand to initiate killing. Thus, activated effector T cells with elevated expression of RT1CE16 were highly susceptible to the killing by the CD8αα+ AP-NK cell. Granule cytolytic perforin/granzyme C from this cell subsequently mediated cytotoxicity, and thus, inhibition of granzyme C effectively attenuated the killing. As it can recognize and eliminate effector autoreactive T cells in the inflamed target tissue, CD8αα+ AP-NK cell not only represents a new type of immune cell involved in immune tolerance, but also is a potential candidate for developing a cell-based therapy for pre-existing autoimmune diseases.
Project description:CD4+ T cells recognize peptide antigens presented on class II Major Histocompatibility Complex (MHC-II) molecules to carry out their function. The remarkable diversity of T cell receptor (TCR) sequences and lack of antigen discovery approaches for MHC-II make profiling the specificities of CD4+ T cells challenging. We have expanded our platform of Signaling and Antigen-presenting Bifunctional Receptors to encode MHC-II molecules presenting covalently linked peptides (SABR-IIs) for CD4+ cell antigen discovery. SABR-IIs can present epitopes to CD4+ T cells and induce signaling upon their recognition, allowing a readable output. Here, we demonstrate that SABR-IIs libraries presenting endogenous and non-contiguous epitopes can be used for antigen discovery. Using SABR-II libraries in conjunction with single cell RNA sequencing, we de-convoluted multiple highly expanded TCRs from pancreatic islets of Non-Obese Diabetic (NOD) mice and identified novel Hybrid Insulin Peptide targets. We compounded antigen discovery by incorporating computational TCR similarity prediction metrics followed by experimental validation. Finally, we showed SABR-IIs presenting epitopes in class II Human Leukocyte Antigen (HLA-II) alleles can be used for antigen discovery for human CD4+ T cells. Taken together, we have developed a rapid, flexible, scalable, and versatile approach for de novo identification of CD4+ T cell ligands from single cell RNA sequencing data using experimental and computational approaches.
Project description:MHC class II positive antigen presenting cells stimulated by polysaccharide A from the capsule of Bacteroides fragilis elicits an innate immune response characterized by the induction of antigen presentation and regulatory (anti-inflammatory) pathways.
Project description:Most clinically applied cancer immunotherapies rely on the ability of CD8+ cytolytic T-cells to directly recognise and kill tumor cells. These strategies are limited by the emergence of MHC-deficient tumor cells and the development of an immunosuppressive tumor microenvironment. The ability of CD4+ effector cells to contribute to anti-tumor immunity independently of CD8+ T-cells is increasingly recognised, but strategies to unleash their full potential remain to be identified. Here, we describe a mechanism through which a small number of CD4+ T-cells is sufficient to eradicate MHC-deficient tumors that escape direct CD8+ T-cell targeting. The CD4+ effector T-cells preferentially cluster at tumor invasive margins where they interact with MHC-II+CD11c+ antigen-presenting cells. We show that Th1-directed CD4+ T-cells and innate immune stimulation reprogram the tumor-associated myeloid cell network towards IFN-activated antigen-presenting and iNOS-expressing tumoricidal effector phenotypes. Together, CD4+ T-cells and tumoricidal myeloid cells orchestrate a remote inflammatory cell death process that indirectly eradicates IFN-unresponsive and MHC-deficient tumors. These results warrant to clinically exploit the ability of CD4+ T-cells and innate immune stimulators as a strategy to complement the direct cytolytic activity of CD8+ T- and NK-cells and advance cancer immunotherapies.
Project description:Reversible MHC class I deficiency on tumour cells is commonly caused by coordinated silencing of antigen-presenting machinery genes and restorable by IFNM-NM-3. Here we describe association of DNA demethylation of selected antigen-presenting machinery gene regulatory regions located in the MHC genomic locus (TAP-1, TAP-2, LMP-2, LMP-7) upon IFNM-NM-3 treatment with MHC class I upregulation on tumour cells. Our novel findings demonstrate that IFNM-NM-3 acts as an epigenetic modifier upregulating the expression of antigen-presenting machinery genes through DNA demethylation. Our data also cast more light on the role of DNA methylation in tumour cell escape from specific immunity. TC-1/A9 cultured cells treated with IFN gama or nothing. 3 biological replicates per condition.
Project description:Reversible MHC class I deficiency on tumour cells is commonly caused by coordinated silencing of antigen-presenting machinery genes and restorable by IFNM-NM-3. Here we describe association of DNA demethylation of selected antigen-presenting machinery gene regulatory regions located in the MHC genomic locus (TAP-1, TAP-2, LMP-2, LMP-7) upon IFNM-NM-3 treatment with MHC class I upregulation on tumour cells. Our novel findings demonstrate that IFNM-NM-3 acts as an epigenetic modifier upregulating the expression of antigen-presenting machinery genes through DNA demethylation. Our data also cast more light on the role of DNA methylation in tumour cell escape from specific immunity. TC-1/A9 cultured cells treated with DAC/TSA or nothing. 3 biological replicates per condition.
Project description:Reversible MHC class I deficiency on tumour cells is commonly caused by coordinated silencing of antigen-presenting machinery genes and restorable by IFNM-NM-3. Here we describe association of DNA demethylation of selected antigen-presenting machinery gene regulatory regions located in the MHC genomic locus (TAP-1, TAP-2, LMP-2, LMP-7) upon IFNM-NM-3 treatment with MHC class I upregulation on tumour cells. Our novel findings demonstrate that IFNM-NM-3 acts as an epigenetic modifier upregulating the expression of antigen-presenting machinery genes through DNA demethylation. Our data also cast more light on the role of DNA methylation in tumour cell escape from specific immunity. RVP3 cultured cells treated with DAC/TSA or nothing. 3 biological replicates per condition.
Project description:Reversible MHC class I deficiency on tumour cells is commonly caused by coordinated silencing of antigen-presenting machinery genes and restorable by IFNγ. Here we describe association of DNA demethylation of selected antigen-presenting machinery gene regulatory regions located in the MHC genomic locus (TAP-1, TAP-2, LMP-2, LMP-7) upon IFNγ treatment with MHC class I upregulation on tumour cells. Our novel findings demonstrate that IFNγ acts as an epigenetic modifier upregulating the expression of antigen-presenting machinery genes through DNA demethylation. Our data also cast more light on the role of DNA methylation in tumour cell escape from specific immunity.
Project description:Reversible MHC class I deficiency on tumour cells is commonly caused by coordinated silencing of antigen-presenting machinery genes and restorable by IFNγ. Here we describe association of DNA demethylation of selected antigen-presenting machinery gene regulatory regions located in the MHC genomic locus (TAP-1, TAP-2, LMP-2, LMP-7) upon IFNγ treatment with MHC class I upregulation on tumour cells. Our novel findings demonstrate that IFNγ acts as an epigenetic modifier upregulating the expression of antigen-presenting machinery genes through DNA demethylation. Our data also cast more light on the role of DNA methylation in tumour cell escape from specific immunity.
Project description:Reversible MHC class I deficiency on tumour cells is commonly caused by coordinated silencing of antigen-presenting machinery genes and restorable by IFNγ. Here we describe association of DNA demethylation of selected antigen-presenting machinery gene regulatory regions located in the MHC genomic locus (TAP-1, TAP-2, LMP-2, LMP-7) upon IFNγ treatment with MHC class I upregulation on tumour cells. Our novel findings demonstrate that IFNγ acts as an epigenetic modifier upregulating the expression of antigen-presenting machinery genes through DNA demethylation. Our data also cast more light on the role of DNA methylation in tumour cell escape from specific immunity.
