Platelet EVs contain an active proteasome involved in protein processing for antigen presentation via MHC-I molecules

In addition to their hemostatic role, platelets play a significant role in immunity. Once activated, platelets release extracellular vesicles (EVs) formed by budding of their cytoplasmic membranes. Because of their heterogeneity, platelet EVs (PEVs) are thought to perform diverse functions. It is unknown, however, whether the proteasome is transferred from platelets to PEVs or whether its function is retained. We hypothesized that functional protein processing and antigen presentation machinery is transferred to PEVs by activated platelets. Using molecular and functional assays, we show that the active 20S proteasome is enriched in PEVs along with MHC-I and lymphocyte costimulatory molecules (CD40L and OX40L). Proteasome-containing PEVs were identified in healthy donor blood, but did not increase in platelet concentrates that caused adverse transfusion reactions. They were, however, augmented after immune complex injections in mice. The complete biodistribution of murine PEVs following injection into mice revealed that they could principally reach lymphoid organs such as spleen and lymph nodes, in addition to the bone marrow, and to a lesser extent liver and lungs. The PEV proteasome processed exogenous ovalbumin (OVA) and loaded its antigenic peptide onto MHC-I molecules which promoted OVA-specific CD8+ T lymphocyte proliferation. These results suggest that PEVs contribute to adaptive immunity through cross-presentation of antigens and have privileged access to immune cells through the lymphatic system, a tissue location that is inaccessible to platelets.

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Genomic programming of antigen cross-presentation in IRF4-expressing human Langerhans cells

10.1101/541383 ◽

2019 ◽

Cited By ~ 1

Author(s):

Marta E Polak ◽

Sofia Sirvent ◽

Kalum Clayton ◽

James Davies ◽

Andres F. Vallejo ◽

...

Keyword(s):

Dendritic Cells ◽

Transcription Factor ◽

Antigen Presentation ◽

Langerhans Cells ◽

Mhc I ◽

Cross Presentation ◽

Mhc Ii ◽

T Cell Immune Responses ◽

Dependent Protein ◽

Chromatin Profiling

AbstractLangerhans cells (LCs) in the epidermis present MHC I and MHC II-restricted antigens thereby priming either CD8 or CD4 T cell immune responses. The genomic programs and transcription factors regulating antigen presentation in LCs remain to be elucidated. We show human LCs are highly efficient in MHC I-antigen cross-presentation but lack the transcription factor IRF8 that is critical in dendritic cells. LC migration from the epidermis enhances their ability to cross-present antigens and is accompanied by the induction of the transcription factor IRF4, whose expression is correlated by scRNA-seq with genes involved in ubiquitin-dependent protein degradation. Chromatin profiling reveals enrichment of EICE and AICE composite DNA binding motifs in regulatory regions of antigen-presentation genes, which can be recognized by IRF4 in conjunction with PU.1 or BATF3 expressed in LCs. Thus, the genomic programming of human LCs including inducible expression of IRF4 with enhanced cross-presentation distinguishes them from conventional dendritic cells.

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MHC class I antigen cross-presentation mediated by PapMV nanoparticles in human antigen-presenting cells is dependent on autophagy

PLoS ONE ◽

10.1371/journal.pone.0261987 ◽

2021 ◽

Vol 16 (12) ◽

pp. e0261987

Author(s):

David Possamaï ◽

Laïla-Aïcha Hanafi ◽

Angélique Bellemare-Pelletier ◽

Katia Hamelin ◽

Paméla Thébault ◽

...

Keyword(s):

Antigen Presentation ◽

T Lymphocyte ◽

Cytotoxic T Lymphocyte ◽

Antigen Presenting Cells ◽

Class I ◽

Class I Mhc ◽

Mhc I ◽

Cross Presentation ◽

Antigen Presenting ◽

Papmv Nanoparticles

Nanoparticles made of the coat protein of papaya mosaic virus (PapMV) and a single-strand RNA were previously shown to be an efficient antigen presentation system for the trigger of cellular immunity. Engineering of PapMV nano with a cytotoxic T lymphocyte epitope was previously shown activating specific T lymphocytes through a proteasome-independent major histocompatibility complex class I (MHC-I) cross-presentation. In this study, we provide new insights into the mechanism of the MHC-I cross-presentation mediated by PapMV nanoparticles. We demonstrate that PapMV nanoparticles do not require the transporter associated with antigen presentation (TAP), but rather depend on lysosome acidification and cathepsin S protease activity for presentation of the T cell epitope. We have also linked the induction of autophagy with this vacuolar MHC-I cross-presentation process. Interestingly, autophagy is induced in antigen-presenting cells after PapMV nanoparticles exposure and inhibition of autophagy reduce MHC-I cross-presentation. This study demonstrates that autophagy is associated with TAP- and proteasome-independent MHC-I cross-presentation. A deeper understanding of the autophagy-dependent MHC-I cross-presentation will be useful in designing vaccination platforms that aim to trigger an efficient cytotoxic T lymphocyte response.

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Faculty Opinions recommendation of TLR signals induce phagosomal MHC-I delivery from the endosomal recycling compartment to allow cross-presentation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718516293.793501152 ◽

2014 ◽

Author(s):

Malini Raghavan ◽

Jie Geng

Keyword(s):

Mhc I ◽

Cross Presentation ◽

Endosomal Recycling

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A Simple Self-Adjuvanting Biomimetic Nanovaccine Self-Assembled with the Conjugate of Phospholipids and Nucleotides Can Induce Strong Cancer Immunotherapeutic Effect

10.21203/rs.3.rs-50125/v1 ◽

2020 ◽

Author(s):

Dan Liu ◽

Jiale Liu ◽

Bing Ma ◽

Bo Deng ◽

Haiyan Xu ◽

...

Keyword(s):

Suppressive Effect ◽

Cpg Odn ◽

Mhc I ◽

Cross Presentation ◽

Biomimetic Nanoparticles ◽

Potential Applications ◽

Survival Prolongation ◽

Self Assembled ◽

Cancer Immunotherapeutic ◽

Cellular Immune

Abstract Background: Biomimetic nanoparticles have potential applications in many fields for their favorable properties. Results: Here, we developed a self-adjuvanting biomimetic anti-tumor nanovaccine, which was self-assembled with an amphiphilic conjugate synthetized with phospholipids of 1, 2-Dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and hydrophilic Toll-like receptor (TLR9) agonists CpG ODN. The nanovaccine could not only provide effective initial antigens stimulation and sustained long-term antigen supply with a controlled release, but also induce antigens cross-presentation via MHC-I pathway initiating CD8+ T-cell responses. Moreover, the dense nucleotides shell around the nanovaccine could promote antigens endocytosis via various receptor-mediated pathways into dendritic cells. And CpG ODN interacted with TLR9 triggering the cytokines secretion of TNF-α and IL-10 further boosted the anti-tumor humoral and cellular immune responses, which led to significant tumor suppressive effect and remarkable survival prolongation. Conclusions: So, this nanovaccine self-assembled with phospholipid-nucleotide amphiphiles can serve as a safe, simple and efficient approach for anti-tumor immunotherapy.

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Variations in MHC class I antigen presentation and immunopeptidome selection pathways

F1000Research ◽

10.12688/f1000research.26935.1 ◽

2020 ◽

Vol 9 ◽

pp. 1177

Author(s):

Anita J. Zaitouna ◽

Amanpreet Kaur ◽

Malini Raghavan

Keyword(s):

Cell Surface ◽

Antigen Presentation ◽

Surface Expression ◽

Structural Features ◽

Class I ◽

Cell Surface Expression ◽

Immune Recognition ◽

Antigen Receptors ◽

Class I Mhc ◽

Mhc I

Major histocompatibility class I (MHC-I) proteins mediate immunosurveillance against pathogens and cancers by presenting antigenic or mutated peptides to antigen receptors of CD8+ T cells and by engaging receptors of natural killer (NK) cells. In humans, MHC-I molecules are highly polymorphic. MHC-I variations permit the display of thousands of distinct peptides at the cell surface. Recent mass spectrometric studies have revealed unique and shared characteristics of the peptidomes of individual MHC-I variants. The cell surface expression of MHC-I–peptide complexes requires the functions of many intracellular assembly factors, including the transporter associated with antigen presentation (TAP), tapasin, calreticulin, ERp57, TAP-binding protein related (TAPBPR), endoplasmic reticulum aminopeptidases (ERAPs), and the proteasomes. Recent studies provide important insights into the structural features of these factors that govern MHC-I assembly as well as the mechanisms underlying peptide exchange. Conformational sensing of MHC-I molecules mediates the quality control of intracellular MHC-I assembly and contributes to immune recognition by CD8 at the cell surface. Recent studies also show that several MHC-I variants can follow unconventional assembly routes to the cell surface, conferring selective immune advantages that can be exploited for immunotherapy.

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Role for ribosome-associated quality control in sampling proteins for MHC class I-mediated antigen presentation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1914401117 ◽

2020 ◽

Vol 117 (8) ◽

pp. 4099-4108 ◽

Cited By ~ 8

Author(s):

Débora Broch Trentini ◽

Matteo Pecoraro ◽

Shivani Tiwary ◽

Jürgen Cox ◽

Matthias Mann ◽

...

Keyword(s):

Quality Control ◽

Antigen Presentation ◽

Mammalian Cells ◽

Adaptive Immune System ◽

Messenger Rnas ◽

Mhc I ◽

Adaptive Immune ◽

Ribosome Stalling ◽

Endogenous Substrates ◽

Insight Into

Mammalian cells present a fingerprint of their proteome to the adaptive immune system through the display of endogenous peptides on MHC-I complexes. MHC-I−bound peptides originate from protein degradation by the proteasome, suggesting that stably folded, long-lived proteins could evade monitoring. Here, we investigate the role in antigen presentation of the ribosome-associated quality control (RQC) pathway for the degradation of nascent polypeptides that are encoded by defective messenger RNAs and undergo stalling at the ribosome during translation. We find that degradation of model proteins by RQC results in efficient MHC-I presentation, independent of their intrinsic folding properties. Quantitative profiling of MHC-I peptides in wild-type and RQC-deficient cells by mass spectrometry showed that RQC substantially contributes to the composition of the immunopeptidome. Our results also identify endogenous substrates of the RQC pathway in human cells and provide insight into common principles causing ribosome stalling under physiological conditions.

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