Minor histocompatibility (H) antigens (Ags) play a detrimental role in the immunopathogenesis of graft-vs-host disease (GvHD) even in recipients of HLA identical bone marrow transplants. Herein, recipient minor H Ags are acquired by donor Ag-presenting cells (APCs) and processed and presented either by MHC class I molecules in a well studied process termed cross-presentation or by class II molecules in a less well understood process called indirect presentation. In a solid organ transplant setting, indirect presentation entails the acquisition, processing and presentation of donor alloantigens by the recipient's APCs. In the case of tumour and microbial Ags, a class II+ APC-likened to a recipient cell-acquires the Ag residing in a class II-negative cell-likened to a donor cell-and processes and presents it to cognate CD4+ (T ) cells. Our mechanistic studies into indirect H presentation revealed that the male pHY and Listeria monocytogenes-derived pLLO Ags upon acquisition by the recipient APCs gained access to the cytosol. Herein, the indirect presentation of pHY was immunoproteasome-dependent yet TAP (cytosol to ER peptide transporter)- and ERAAP (ER-associated amino-peptidase)-independent. Surprisingly, both TAP and ERAAP either diverted or destroyed pHY and pLLO thereby reducing their presentation to TH cells. These finding led to two critical questions: (a) does the class I Ag processing (CAP) machinery globally impact class II-restricted Ag presentation;and (b) how do cytosolic Ags gain access to the endo/lysosomes for indirect presentation? In trying to understand how the cytosolic pHY returned to the endo/lysosomes for presentation, we ruled out the role for macro-autophagy as indirect presentation of HY proceeded in mice in which dendritic cells were conditionally deficient for Atg5. Instead, we found that the homodimeric TAP-like (TAP-L)-an orphan endo/lysosomal peptide transporter distinct from ER- resident TAP1/TAP2-was needed for indirect pHY presentation. Predicated on our functional studies, herein, we seek to gain biochemical insights into indirect presentation mechanism(s). Hence, we will test the central hypothesis that the class I Ag processing machinery regulates the pool of certain cytosolic Ags available for class II-restricted indirect presentation. Such Ags are processed in the cytosol and transported to the endo/ lysosomes in a TAP-L-dependent mechanism. To test this hypothesis, we will (a) determine whether the CAP machinery globally impacts H2Ab-restricted processing and presentation of self- or microbe-derived cytosolic Ags;(b) determine how cytosolic Ags enter the endo/lysosomes for indirect presentation;and (c) determine whether the CAP machinery impacts cytosolic Ag specific CD4+ T cell repertoire. Successful completion of this work will yield new biochemical insight(s) into indirect Ag presentation by class II molecules. A mechanistic understanding of class II-restricted indirect Ag presentation is critical not only for developing ways to circumvent/treat GvHD but also for vaccine design as this process is operative in the presentation of cytosolic Ags (viral, bacterial, parasitic) to TH cells and, hence, for vaccine design against tumours and pathogens. !
Bone marrow transplantation has emerged as a therapeutic modality for various end-stage blood cell diseases such as anemias, lymphomas and leukemias. Even though matching major histocompatibility complex antigens has improved transplant outcome, minor histocompatibility antigen mismatches are known to cause, oft-times fatal, graft-vs-host disease. The goal of this research is to gain a mechanistic understanding of how minor histocompatibility antigens are processed and presented to T cells so as to develop ways to circumvent or treat fatal, graft-vs- host disease.
|Gilchuk, Pavlo; Knight, Frances C; Wilson, John T et al. (2017) Eliciting Epitope-Specific CD8+ T Cell Response by Immunization with Microbial Protein Antigens Formulated with ?-Galactosylceramide: Theory, Practice, and Protocols. Methods Mol Biol 1494:321-352|
|Gilchuk, Pavlo; Hill, Timothy M; Guy, Clifford et al. (2016) A Distinct Lung-Interstitium-Resident Memory CD8(+) T Cell Subset Confers Enhanced Protection to Lower Respiratory Tract Infection. Cell Rep 16:1800-9|
|Hastings, Andrew K; Gilchuk, Pavlo; Joyce, Sebastian et al. (2016) Novel HLA-A2-restricted human metapneumovirus epitopes reduce viral titers in mice and are recognized by human T cells. Vaccine 34:2663-70|
|Joyce, Sebastian (2015) Immunoproteasomes edit tumors, which then escapes immune recognition. Eur J Immunol 45:3241-5|
|Erickson, John J; Lu, Pengcheng; Wen, Sherry et al. (2015) Acute Viral Respiratory Infection Rapidly Induces a CD8+ T Cell Exhaustion-like Phenotype. J Immunol 195:4319-30|
|Wen, Sherry C; Schuster, Jennifer E; Gilchuk, Pavlo et al. (2015) Lung CD8+ T Cell Impairment Occurs during Human Metapneumovirus Infection despite Virus-Like Particle Induction of Functional CD8+ T Cells. J Virol 89:8713-26|
|Spencer, Charles T; Bezbradica, Jelena S; Ramos, Mireya G et al. (2015) Viral infection causes a shift in the self peptide repertoire presented by human MHC class I molecules. Proteomics Clin Appl 9:1035-52|
|Gilchuk, Pavlo; Hill, Timothy M; Wilson, John T et al. (2015) Discovering protective CD8 T cell epitopes--no single immunologic property predicts it! Curr Opin Immunol 34:43-51|
|Hastings, Andrew K; Erickson, John J; Schuster, Jennifer E et al. (2015) Role of type I interferon signaling in human metapneumovirus pathogenesis and control of viral replication. J Virol 89:4405-20|
|Hill, Timothy M; Gilchuk, Pavlo; Cicek, Basak B et al. (2015) Border Patrol Gone Awry: Lung NKT Cell Activation by Francisella tularensis Exacerbates Tularemia-Like Disease. PLoS Pathog 11:e1004975|
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